Modeling of halal supplier flexibility criteria in the food supply chain using hybrid ISM-MICMAC: A dynamic perspective

Abstract

In the context of the halal supply chain, the need for flexibility of halal suppliers is increasing along with changes in regulations, policies, markets, and technology that change dynamically. Therefore, more systematic and dynamic modeling of flexibility criteria for halal suppliers is needed to improve the quality of halal supply chain management as a whole. The purpose of this study is to identify the criteria for halal suppliers by considering flexibility in the context of a halal supply chain. In this study, modeling the criteria for the flexibility of halal suppliers is carried out using the Interpretive Structural Modeling—Matriced’ Impacts Croisés Appliquée á un Classement (ISM-MICMAC) hybrid approach and a dynamic perspective. This study resulted in 11 criteria for halal suppliers which were divided into four levels in the ISM hierarchical structure. The criteria were spread over three quadrants of the MICMAC analysis, namely independent, linkage, and dependent. The results of the ISM and MICMAC approaches are then represented in a causal loop diagram which consists of an amplifying loop and a closed loop. The reinforcing circle consists of the criteria of responsibility-service-security-trust, while the balancing circle consists of traceability and costs. Even though the flexibility criterion is not in between the two loops, the criterion still influences other halal supplier criteria. This shows that flexibility criteria have important relationships and influences in the context of halal supply chain management.

Keywords:

• Flexibility
• halal supplier
• supply chain
• ISM
• MICMAC

1. Introduction

The trend of demand for halal products increases along with the increasing Muslim population and religious awareness, which affects a healthy lifestyle (Tieman, 2011). Moreover, Muslim countries not only consume halal products, but halal products are also in demand by other non-Muslim countries (Mohamed et al., 2020; Rejeb et al., 2021). This is because halal is not only an Islamic law but also includes quality, food safety, cleanliness, and product safety. On the other hand, the issue of halal products has recently received much public attention for the many cases of food scandals that have occurred, for example, contamination of halal and non-halal food (Ab Rashid & Bojei, 2020), product recall (Ali, Zhan, et al., 2017; M. H. Ali & Suleiman, 2018), the risk of contamination in the food supply chain (Soon et al., 2017; Yaacob et al., 2021) and product counterfeiting (Rejeb et al., 2021).

According to S. Khan et al. (2022) and A. U. Khan and Ali (2021) asserts that the causes of halal food cases are due to supplier failure to comply with halal food quality standards, supplier failure to maintain product integrity, supplier failure to separate the allocation of halal products and suppliers using illegal additives in their products. In addition, there is a need for raw materials from around the world with suppliers and sub-suppliers abroad (Opara & Mazaud, 2001), which can lead to cross-contamination during the distribution process Lee et al. (2019) (Maman & Jie, 2017).; Furthermore, suppliers have several incidental involvements in triggering halal products to become non-halal due to the supplier’s error in using pork enzymes in supplying raw materials for Ajinomoto products. This incident resulted in product recalls and a boycott of halal certification. Another halal-certified product contaminated with pork due to the supplier’s carelessness is Cadbury Malaysia chocolate (Ali, Zhan, et al., 2017). This is because mistakes in choosing suppliers result in significant hazards in terms of food safety which have an impact on the company experiencing huge losses.

The results of research conducted by Soon et al. (2017) revealed that the most common problems of food that occurred were the presence of pig DNA in food products, mixtures of halal meat and pork, and falsification of halal labels. However, most cases of halal food are found in raw materials. This shows that mistakes in choosing suppliers are the main cause of this case, which in turn can endanger food safety and have a negative impact on companies that experience significant losses. Therefore, it is necessary to verify the halalness of raw materials with certificates provided by suppliers or consumers in the market (Zakaria, 2008). However, it should be noted that the halal standards used by halal certification organizations in the world may differ slightly from one another. In conclusion, Halal food producers must choose the right suppliers and strictly monitor the supply chain to deal with considerable food safety risks. In addition, food producers can ensure the halalness of raw materials by carrying out proper verification (van der Spiegel et al., 2012). Thus, halal food producers can ensure the quality and safety of the finished products they produce and minimize losses caused by cases of non-halal food.

Thus, the problem of suppliers in halal products from year to year has not been resolved. This is evidenced by Maman and Jie (2017), who stated that suppliers’ most considerable potential risk in the halal supply chain lies. Furthermore, in the following study, A. U. Khan and Ali (2021) produced the same outcome: halal food’s risk lies in the supplier’s quality. This indicates that problems with halal food suppliers are still prominent. One of the reasons is limitations on suppliers of halal raw materials (M. H. Ali et al., 2016). Even though suppliers are the basis of the halal food management system, it plays a vital role in determining the final product according to Islamic law (S. Khan et al., 2022). In essence, according to Talib and Johan (2012), concern for suppliers of halal raw materials is essential because suppliers are the upstream part of halal food producers who significantly influence the integrity of the halal supply chain. Therefore, if the quality of suppliers is not in accordance with halal standards, the halal supply chain would be threatened (Feizollah et al., 2021). Therefore, it is crucial to explore supplier management in the halal supply chain to overcome supplier problems in the supply chain so that the raw materials delivered by suppliers meet Islamic law.

However, managing suppliers in the halal supply chain are not easy. The biggest challenges in managing halal are the number of accidents involving suppliers and the limited number of halal suppliers compared to conventional suppliers. In addition, another difficulty is related to the scarcity of credible halal-certified suppliers in the food industry (Tieman & Ghazali, 2014). One way to deal with limited suppliers is to consider the element of flexibility. Flexibility can improve the performance of the halal supply chain so that suppliers can respond to unexpected changes and face possible risks (Tieman et al., 2012). Similarly, Ali, Tan, et al. (2017) stated that not only food quality but flexibility is also a key performance indicator in the food supply chain.

According to (Manzouri, Rahman, Saibani, and Zain (2013), combining flexibility is important in adjusting halal production. This is because halal needs involve special rules and conditions in the production and consumption of products that must be obeyed to ensure the halalness of these products (Kristanto & Kurniawati, 2023). For this reason, suppliers with flexible criteria would find it easier to respond to changes by adjusting the production process in accordance with applicable halal requirements (Kusrini et al., 2018). Thus flexibility becomes important in the context of halal needs because changes in halal requirements can occur from time to time, besides that market demand for halal products can vary and some raw materials may be considered not halal or haram (Wahyuni, Nazaruddin, Amalia Frastika, & Budiman, 2021).

Therefore, halal suppliers could show flexibility in meeting halal needs. They would have an advantage in winning business and building long-term relationships with halal customers (S. Khan et al., 2021). In addition, in the context of globalization and international trade, halal suppliers with flexibility criteria can have a greater competitive advantage in reaching a wider market (Hashemi et al., 2022). Moreover, flexibility criteria for halal suppliers can have an impact on the quality of halal products produced, minimize the risk of contamination of non-halal materials and strengthen the image of producers who care about the needs of halal customers (S. Khan et al., 2021).

Even though halal suppliers with flexibility criteria have great potential in fulfilling halal requirements. However, studies explaining the factors that affect flexibility criteria for halal suppliers are still limited and relatively few studies specifically address halal suppliers. In the past five years, there have only been five studies on halal suppliers. Dahlan et al. (2017) identified behavioral criteria and sub-criteria among halal food suppliers that can influence supplier decisions in meeting halal standards. Furthermore, Fujiwara (2017) proposes several risk mitigation strategies for supplier management in the halal food supply chain. The following discussion focuses more on the quality of halal supplier services on the performance of halal logistics (Masudin, Jie, et al., 2020).

It is still rare and limited based on previous research that reviews the criteria for halal suppliers. Only two studies by Dahlan et al. (2017) and Başaran and Çakir (2021) examine halal criteria. The first study focuses more on four criteria, while the later article investigates several criteria for halal suppliers, a total of twelve criteria with forty-eight sub-criteria. However, the criteria generated in previous studies have not sufficiently paid attention to the rules of applying Islamic business, which requires flexibility as part of the dynamism of Islamic Sharia. This is in line with the study by Fujiwara (2017), which states that flexibility is one of the risk mitigation strategies for halal food suppliers. With the element of flexibility in halal suppliers, suppliers are expected to meet halal requirements and adapt to changes in government policies, companies, and consumer demands.

In this study, the flexibility criteria are considered to identify criteria that are relevant to halal suppliers and the results of identifying criteria for halal suppliers are modeled to analyze the relationship between the criteria involved in halal suppliers. Next, make a causal loop diagram to model and determine the relationship and impact of flexibility criteria with other halal supplier criteria. This would help in knowing the driving criteria or supporting criteria that are relevant to halal suppliers and can be used as an appropriate basis for determining halal suppliers. The research focused on the criteria of the flexibility of halal suppliers in the food supply chain and a dynamic perspective is limited. Therefore, this research would focus on modeling the flexibility criteria for halal suppliers using the ISM-MICMAC hybrid approach and a dynamic perspective. This is because the ISM method is a method that is very popular in helping solve various complex problems to be easier to understand (Tyagi et al., 2021).

Thus, this research has two research questions (RQ). The first RQ answers how to model the flexibility criteria of halal suppliers in the food supply chain by integrating ISM and MICMAC in the food supply chain. The second RQ explores how the dynamic perspective can be applied in modeling the flexibility criteria of halal suppliers in the food supply chain, and how this can help halal industry sectors to develop better business strategies in dealing with changing halal requirements and customer needs. The research results can be used as a reference and help improve the quality of halal products, as well as contribute to the development of theory and practice of food supply chain management in the context of the halal food industry.

The structure of this research is divided into five parts, consisting of part 1 explaining the research problem’s background. The literature review related to halal supplier flexibility is described in section 2. Section 3 describes the stages of the research, starting from the process of identifying criteria to the ISM method and system dynamics. Section 4 presents the research results, while section 5 elaborates on the discussion. Finally, section 6 is the conclusion and limitations of the study.

2. Literature review

2.1. Halal supplier criteria

Research on halal supplier criteria has received much attention from academics and practitioners. Most studies of halal supplier criteria involve quality criteria in their discussion. According to Figure 1, it is recorded that more than 18% of articles that discuss halal suppliers include quality criteria. For example, Masudin et al. (2021) consider quality the most important criterion. Furthermore, Dahlan et al. (2017) indicate that quality is the most important consideration for buyers in choosing halal suppliers.

Figure 1. Halal supplier criteria.

After quality, buyers must consider the following criteria for choosing halal suppliers: cost, traceability, and halal certification. These three criteria appear with the same percentage (10%). Several studies on the selection of halal suppliers include cost criteria (Başaran & Çakir, 2021), traceability (Handayani et al., 2021; Tan et al., 2020), and halal certification (Zulfakar et al., 2019). Moreover, the discussions about halal suppliers also investigate service, supplier audit performance, trust, and food safety criteria to select a supplier.

2.2. Halal supplier flexibility

Many policies are forced to be issued by buyers when environmental conditions are uncertain in selecting suppliers. This is so that the supplier can accommodate the buyer’s needs according to organizational goals. From the supplier’s perspective, this flexibility would make it easier for them to respond to changes in demand made by buyers. In supply chain management, a flexibility criterion has been proven to improve supply chain performance (Tieman et al., 2012). Ali, Tan, et al. (2017) also stated that flexibility and quality are critical indicators of food chain performance.

The Source of supply may be affected by risk drivers that increase the level of supply risk, which can cause losses. Therefore, risk mitigation is needed to prevent adverse consequences for suppliers and buyers. Jüttner et al. (2003) classified risk mitigation into four strategies: control, avoidance, cooperation, and flexibility. A flexibility strategy in mitigating supply risk is used to increase responsiveness to delays, cancellations, postponements, and changes in quantities and specifications. Flexibility also includes the strategies of localizing sourcing and multiple sourcing. Heydari et al. (2020) modeled a quantity flexibility contract and fraction sourcing in a two-echelon supply chain system and found that the flexibility strategy could increase the profit of the supply chain. S. Khan et al. (2021) stated that in the case of the limited halal supplier, a multi-sourcing strategy could be applied to eliminate the risk and enhance supplier flexibility. Another flexibility strategy for other significant risks of limited availability of halal raw materials can be applied by promoting a halal brand in the international market. This flexibility strategy could attract global supplier to adopt halal practice. The other most risk of sourcing halal food product is about the unavailability of a halal additives or emulsifier. The untolerable risk in halal food product can be mitigated by flexibility strategy such as halal emulsifier substitution.

2.3. Multi-criteria supplier selection approaches

Most supplier selection discussions involve multi-criteria decision-making. The decision-making process involving many suppliers and multi-criteria in a dynamic environment requires a particular approach to get the criteria that best suit the buyers’ needs. There have been many approaches that have been used to determine supplier selection criteria in a dynamic environment. Beikkhakhian et al. (2015) conducted a study to identify supplier selection criteria in the agile field. They used interpretive structural modeling (ISM) combined with AHP and TOPSIS to categorize and rank the criteria to increase suppliers’ agility. Another study (Chan, 2003) investigated tangible criteria for supplier selection using an interactive selection model focused on determining buyer and supplier relationships. Moreover, Kumar et al. (2015) presented a MICMAC (Matriced’ Impacts Croisés Appliquée á un Classement) approach to the successful supplier selection process.

In the context of halal supplier selection, the application of approaches in determining criteria for halal supply has not been given much attention recently. Başaran and Çakir (2021) investigated 12 halal supplier selection criteria for food using the fuzzy COPRAS method. The study suggested that the proposed approach could offer a practical method for supplier selection and multi-criteria decision-making problems. Another study by S. Khan et al. (2022) applies the Best and Worst Method (BMW) to explore the barriers to managing the halal practice, including supplier selection. Masudin et al. (2018) have also taken the investigation of halal criteria for halal food, while Mustapha, Kamaruddin, Hamid, and Samah (2016) used the Analytics Hierarchy Process (AHP) approach to determine criteria and sub-criteria among halal food suppliers. Another study by Forrester (1994a) applied Analytical Hierarchy Process (ANP) to determine the prioritizing risks of the halal meat supply chain, including supplier selection. Moreover, Masudin, Fernanda, et al. (2020) applied structural equation modeling (SEM) for quantitative research to investigate halal supplier criteria’ relationship with halal logistics performance.

2.4. Flexibility criteria and methods used in previous supplier selection research

Flexibility is one of the resilience criteria used as an indicator in supplier selection (Leong et al., 2022). This is in line with Baki (2021), who states that the flexibility criterion produces the highest weight as an essential criterion for measuring supplier competence. Likewise, the results of other work (Bodaghi et al., 2018) revealed that 90% of respondents mentioned flexibility as an important component in maintaining competitiveness. Moreover, considering flexibility criteria in evaluating suppliers can make businesses more responsive in dealing with most supply chain uncertainties (Das, 2011). Although the flexibility criteria can make suppliers flexible and contribute to the flexibility of the entire supply chain. However, in the context of halal suppliers, the flexibility criteria have not been considered an indicator for selecting halal suppliers. As Table 1 shows that no previous research has been found that considers flexibility criteria in the selection of halal suppliers, because it requires an analysis of the relationship and impact of flexibility criteria on other halal supplier criteria. For that we need the right method approach in order to know the role of the flexibility criteria against the criteria of other halal suppliers.

Table 1. Comparison of proposed studies with relevant studies

Author	Main contribution	Output	Number of supplier criteria	Flexibility criteria	Methods used	Halal factor	Object
Leong, Wong, and Wong (2022)	Supplier selection	Supplier ranking	7 criteria	Yes	Grey Relational Analysis (GRA) -BWM-TOPSIS	No	food manufacturing
Sonar, Gunasekaran, Agrawal S, and Roy (2022)	Identify supplier and supplier selection criteria	supplier ranking	12 criteria	Yes	Interpretive Structural Modeling (ISM)	No	NA
A. U. Khan and Ali (2021)	Supplier selection	Supplier ranking	15 criteria	No	ISM and fuzzy VIKOR	No	frozen food industry
Nasrollahi et al. (2021)	Identify supplier and supplier selection criteria	Supplier criteria and supplier ranking	19 criteria	Yes	Interpretive Structural Modeling (ISM)-Fuzzy DEMATEL	No	NA
Başaran and Çakir (2021)	Supplier selection	Supplier ranking	12 criteria	No	COPRAS-F	Yes	food industry
Tham et al. (2020)	Supplier selection	Supplier ranking	22 criteria	Yes	ISM and fuzzy TOPSIS	No	NA
Y. Chen et al. (2018)	supplier selection	supplier ranking	6 criteria	No	TISM and fuzzy ANP	No	Chinese food industry
Petrudi et al. (2018)	Suppliers evaluation	Supplier criteria and supplier ranking	14 criteria	Yes	Interpretive structural modeling (ISM), Fuzzy Preference Programming (FPP), Analytical Network Process (ANP), Fuzzy TOPSIS	No	food industry
Gavareshki et al. (2017)	Supplier selection	Supplier ranking	13 criteria	No	Interpretive structural modeling, Fuzzy MICMAC analysis, Fuzzy AHP, and Vikor method.	No	NA
R. Ali et al. (2017)	Identify supplier criteria	Supplier criteria	5 criteria	No	qualitative study	Yes	food industry
Iberahim et al. (2016)	Identify supplier criteria	Supplier criteria	4 criteria	No	Analytic Hierarchy Process	Yes	food industry
Beikkhakhian et al. (2015)	Selection criteria and ranking suppliers	Supplier criteria and supplier ranking	10 criteria	No	ISM- fuzzy TOPSIS-AHP	No	NA
This study	Identify supplier criteria	Relationship between criteria and suppliers	11 criteria	Yes	Integration of ISM-MICMAC- system dynamic for causal loop diagram	Yes	food industry

In finding out the proper method, this study begins with conducting a literature review on the Scopus database using the keywords “selection”, “supplier” or “supply chain”. The literature review results in Table 1 explain that the ISM-MICMAC method has been adopted in the supplier field of study. This method can be used to obtain criteria and select suppliers. Moreover, Figure 2 further explains the scope of the ISM method in suppliers, where ISM is more often used to analyze supplier criteria, selection, and performance. Furthermore, in identifying the relationship between flexibility criteria and other halal supplier criteria, it is visualized using a causal loop diagram (CLD). In principle, CLD allows for a better interpretation of dynamics, while the ISM process establishes relationships and ordering dimensions among variables that enable priority decisions (Eshun & Chan, 2021).

Figure 2. The scope of the ISM method in suppliers.

3. Method

This study uses a systematic literature review approach and hybrid ISM-MICMAC with the dynamic system method. First, a systematic literature review is carried out by collecting publications on halal suppliers through the Scopus database using the keywords supplier and halal and supply chain. These keywords resulted in 31 papers consisting of 21 journal papers and 11 proceedings papers, starting from 2012 to 2021. A systematic literature review in the paper extracts the criteria for halal suppliers from previous research. Meanwhile, to validate the criteria for halal suppliers using structured interview techniques with experts consisting of academics, professionals, practitioners, and MUI (Indonesian Council of Religious Scholars). The list of expert teams involved in the validation of halal supplier criteria can be seen in Table 1. Furthermore, validating the halal supplier criteria as input for the ISM technique is used in mapping the relationship between the flexibility criteria and other halal supplier criteria. Meanwhile, another approach uses MICMAC to map the criteria for halal suppliers based on the clustering of the MICMAC concept. The last method uses a dynamic system to simulate the flexibility criteria model with the criteria for other halal suppliers. This is in line with the goal of system dynamics: to understand and investigate the behavior of systems that incorporate causal relationships (Forrester, 1994b). The model built in this study uses a policy scenario that considers the element of flexibility criteria for halal suppliers. This is to determine the relationship and the impact of flexibility on halal suppliers. The model is presented through a causal loop diagram so that the variables and details of the problem would be easily understood in depth. More details about the ISM-MICMAC hybrid method and the dynamic system can be seen in Figure 3.

Figure 3. ISM-MICMAC hybrid method and the dynamic system.

3.1. Interpretive structural modelling and MICMAC approach

The selection of the ISM method is appropriate in this study because ISM can be used in the initial phase to identify structures within the system (Sushil, 2012). ISM can also analyze the relationship between certain variables (Tham et al., 2020). The system ISM method is unclear, and complex and complicated situations can be well-defined through expert consultation (Dalvi & Kant, 2018). Expert experience is needed in this research to formulate a multilevel structure and knowledge of the factors considered (A. U. Khan & Ali, 2021). This is important because the relationship between system variables depends on industry experts’ organized, experienced, and constructive thinking (Warfield, 1982). In this study, the ISM modeling stage refers to several researchers such as A. U. Khan and Ali (2021), Sushil (2012), and Tham et al. (2020). At the stage of making the MICMAC analysis, it is divided into four different groups according to A. U. Khan and Ali (2021), including:

• Autonomous variables formulate the first cluster representing the criteria with the weak driving force and dependency strength.

• The dependent variable formulates a second cluster representing the variable or factors with weak driving forces and strong dependency forces.

• Variable linkage formulates a third cluster representing a variable or factor with a solid driving force and dependence.

• The independent variable formulates the fourth cluster representing the variable or factors with solid driving forces and weak dependency forces.

3.2. Building a causal loop diagram model

At this stage, the causal relationship between variables is obtained from the ISM output in the previous stage. The causal loop diagram illustrates the causal relationship of a circular system that provides an explicit conceptualization of system dynamics (Eshun & Chan, 2021), making it easier to analyze the relationship between each criterion of a halal supplier quantitatively. Establishing a causal relationship is connected with an arrow depicting the direction of the connection. The arrow has two indicators negative (-) or positive (+). In describing cause and effect in the opposite direction, it would be represented by a negative sign (-). In contrast, if it changes in the same direction, it is represented by a positive sign (Khoddami et al., 2021). This means that the relationship is a reinforcing relationship. In Figure 4, the connecting arrows represent the feedback loop as a balancing loop (B) or an amplifier (R). Loop B acts as stability by reducing changes, while Loop R acts in a system that is experiencing a continuous increase (Eshun & Chan, 2021)

Figure 4. Causal loop diagram.

Source: Roubík et al. (2020)

3.3. Integration of ISM-MICMAC and system dynamics (ISM-MICAMC-SD)

The ISM method and system dynamics proposed in this paper are adopted from Etemadinia and Tavakolan (2021), but there are differences in the stages of ISM. This paper uses ISM and MICMAC analysis, while the research of Etemadinia and Tavakolan (2021) is sufficient until dynamic systems follow the graph form diagram. This study integrates the ISM-MICMAC-SD method, which aims to sharpen the ability of dynamic systems to analyze flexibility criteria for halal suppliers and make dynamic models more structured. The integration of ISM-MICMAC-SD can provide more accurate results in analyzing the system. This is because one model covers the shortcomings of the other (Etemadinia & Tavakolan, 2021). Figure 3 describes the stages in the integration of ISM-MICMAC-SD, where the ISM-MICMA-SD modeling goes through a multi-stage process, but on the other hand, if there are problems that occur at each stage of the process, backtracking and iteration processes can be carried out to understand and fix the problem. ISM in this study plays a role in visualizing the main interaction variables from the system through a diagram called a graph and MICMAC analysis used for clustering criteria for halal suppliers. Furthermore, the dynamic system plays a role in carrying out hypotheses in formulating and presenting in the form of a causal loop diagram which is continued according to the stages in the dynamic system.

4. Results

The results section presents the results of the research in a systematic and structured manner which can provide a more detailed understanding of the research that has been conducted. The results of this study are expected to provide a solid basis for the conclusions and recommendations made in the next section.

4.1. Structural self-interaction matrix (SSIM)

This study’s structural self-interaction matrix (SSIM) is a contextual relationship with halal supplier criteria generated based on expert opinion assessment. This assessment aims to determine the reciprocal relationship between halal supplier criteria i and halal supplier criteria j, represented by four symbols, namely (V, A, X, O), as shown in Table 2. The use of four symbols in assessing halal suppliers’ criteria adopts the research of Mabrouk (2020). The symbol “V” means that criterion i affects criterion j, such as the quality criterion affecting food safety and the traceability criterion affecting responsibility and delivery. Similarly, the criteria for halal certification affect the same three criteria, namely responsibility, and delivery. Other criteria, such as food safety, affect the criteria of trust, SAP (supplier audit performance), and delivery. The trust criteria affect responsibility and delivery. Thus, “V” represents the relationship between the two criteria. Meanwhile, the symbol “A” means that criterion j encourages or affects criterion i; for example, the traceability criterion affects quality. Five criteria affect one criterion, namely the criteria of flexibility, responsibility, SAP, service, and halal certification that affect costs. It differs from one flexibility criterion, which affects four other criteria: cost, food safety, trust, and delivery. Therefore use “A” to represent the relationship between the two. Furthermore, the symbol “X” is used to see between criteria that affect each other. For example, quality criteria influence each other on cost criteria, halal certification, SAP, and delivery. Likewise, other criteria, such as traceability criteria with SAP and food safety, affect each other. Finally, the symbol “O” indicates no relationship between criterion j and criterion i. For example, the quality criteria with flexibility, responsibility, trust, and service are unrelated. In addition, the cost criterion has nothing to do with trust. Traceability criteria have nothing to do with flexibility and trust criteria. Likewise, the delivery and flexibility criteria have no relationship with the SAP criteria. Thus, the symbol “O” is used to represent if there is no relationship between the two criteria or if there is no valid relationship between the variables.

Table 2. Expert team

Expert	Status	Position	Education	Work experience	Sector
A	Practitioner	Procurement manager	Master	12 years	Meat processing industry
B	Practitioner	Quality assurance manager	Bachelor	14 years	Meat processing industry
C	Practitioner	Supply chain manager	Master	10 years	Meat processing industry
D	Professional	MUI representative	Doctor	7 years	Fatwa council
E	Academics	Lecturer and researcher	Doctor	12 years	Halal supply chain

4.2. Initial reachability matrix

The initial reachability matrix (IRM) is a transformation process from the SSIM matrix into IRM, symbols V, A, X, and O into binary matrix form (1 and 0). For example, if the SSIM matrix is symbol A, then (i, j) in IRM is replaced by 0, and (j, i) is 1. For more details on building the reachability matrix, see section 3.1. Meanwhile, the results of the transformation of the SSIM matrix into IRM are presented in Table 3, which shows the transformation of the SSIM matrix into IRM in describing the interrelationships between the eleven criteria for halal suppliers. The full explanation is in Table 3 as follows. Suppose the X symbol in the SSIM matrix is indicated for the quality criteria. In that case, the quality criteria in the Initial reachability matrix (IRM) would be 1 in cells (i, j), as well as the halal certification criteria for cells (j, i). This would be different if the SSIM matrix symbol A with quality criteria in cells (i, j), then the IRM value in the cell quality criteria (i, j) becomes 0, and the traceability criteria in cells (j, i) becomes 1. While the symbol V has a value the opposite of symbol A, for example, the SSIM matrix has a value of V for quality criteria, the IRM on the quality criteria cells (i, j) becomes 1, and the food safety cell criteria (j, i) is 0.

Table 3. Structural self-interaction matrix (SSIM) of the relationship between halal supplier criteria

Factors (i/j)	Criteria	11	10	9	8	7	6	5	4	3	2
1	Quality	O	X	O	X	O	V	O	X	A	X
2	Cost	A	X	A	A	O	V	A	A	X
3	Traceability	O	V	V	X	O	X	A	A
4	Halal certification	X	V	V	X	V	A	X
5	Service	X	X	A	A	V	X
6	Food safety	A	V	X	V	V
7	Trust	A	V	V	A
8	SAP(supplier audit performance)	O	O	V
9	Responsibility	O	A
10	Delivery	A
11	Flexibility

4.3. Partitioning level in Final Reachability Matrix (FRM)

Final reachability results are the basis for making a graph by dividing it into three sets: reachability, antecedent, and intersection. The reachability set consists of the element and other elements that may be achieved. In contrast, the antecedent set consists of the elements and other elements that may be achieved (Thakkar et al., 2005). Besides that, the reachability matrix set consists of each variable (i) in all rows (j) marked with 1 and 1 × .Likewise, the antecedent set consists of variables in column (j) that correspond to each variable (i) marked with 1 and 1 × .Meanwhile, the intersection set is the intersection of the reachability set with the antecedent set listed in the last column. Table 4 shows the detailed level partition matrix results for eleven criteria with four iterations resulting in four levels.

Table 4. Final reachability matrix criteria for halal suppliers

Factors (i/j)		11	10	9	8	7	6	5	4	3	2	1	Driving Power
1	Quality	0	1	0	1	0	1	0	1	0	1	1	6
2	Cost	0	1	0	0	0	1	0	0	1	1	1	5
3	Traceability	0	1	1	1	0	1	0	1*	1	1	1	8
4	Halal Certification	1	1	1	1	1	0	1	1	1	1	1	10
5	Service	1	1	1*	1*	1	1	1	1	1	1	0	10
6	Food safety	1*	1	1	1	1	1	1	1	1	0	1*	10
7	Trust	0	1	1	1*	1	0	0	0	0	0	0	4
8	SAP(supplier audit performance)	0	0	1	1	1	0	1	1	1	1	1	8
9	Responsibility	0	0	1	0	0	1	1	0	1*	1	0	5
10	Delivery	0	1	1	0	0	0	1	0	0	1	1	5
11	Flexibility	1	1	1*	1*	1	1	1	1	0	1	0	8
12	Dependence Power	4	9	9	8	6	7	7	7	7	9	7

The first iteration, which occupies level I (quality criteria), is the only criterion with similarities between the variables in the reachability and antecedent sets. Thus the quality criterion is the single criterion that occupies a higher level in the ISM model than other criteria. Once level I is identified, it would be removed from consideration. Then, the same process is repeated to determine the next level’s criteria for other halal suppliers. This process continues until the level of each halal supplier criteria is found. These levels help build ISM diagrams and models. For example, Table 5 shows a breakdown of the partitioning levels for the eleven criteria with four levels. While Table 6 is a sequence of halal supplier criteria based on the order of the results of the matrix partition level.

Table 5. Level partition matrix iteration 1–4

Iteration	Criteria	Reachability Set	Antecedent Set	Intersection set	Level
Iteration I	Quality	1,2,4,6,8,10	1,2,3,4,6,8,10	1,2,4,6,8,10	Level 1
	Cost	1,2,3,6,10	1,2,3,4,5,8,9,10,11	1,2,3,10
	Traceability	1,2,3,4,6,8,9,10	2,3,4, 5,6,8,9	2,3,4,6,8,9
	Halal Certification	1,2,3,4,5,7,8,9,10,11	1,3,4,5,6,8,11	1,3,4,5,8,11
	Service	2,3,4,5,6,7,8,9,10,11	4,5,6,8,9,10,11	4,5,6,8,9,10,11
	Food safety	1,3,4,5,6,7,8,9,10,11	1,2,3,5,6,9,11	1,3,5,6,9,11
	Trust	7,8,9,10	4,5,6,7,8,11	7,8
	SAP (supplier audit performance)	1,2,3,4,5,7,8,9	1,3,4,5,6,7,8,11	1,3,4,5,7,8
	Responsibility	2,3,5,6,9	3,4,5,6,7,8,9,10,11	3,5,6,9
	Delivery	1,2,5, 9,10	1,2,3,4,5,6,7,10,11	1, 2,5,10
	Flexibility	2, 4,5,6,7,8,9,10,11	4,5,6,11	4,5,6,11
Iteration II	Cost	3	3,5,9,11	3	Level II
	Traceability	3,9	3,5,9	3,9	Level II
	Halal Certification	3,5,7,9,11	3,5,11	3,5,11
	Service	3,5,7,9,11	5,9,11	5,9,11
	Food safety	3,5,7,9,11	3,5,9,11	5,9,11
	Trust	7,9	5,7,11	7
	SAP(supplier audit performance)	3,5,7,9	3,5,7,11	3,5,7
	Responsibility	3,5,9	5,7,9,11	5,9
	Delivery	5,9	3,5,7,11	5
	Flexibility	5,7,9,11	5,11	5,11
Iteration III	Halal Certification	5,7,11	5,11	5,11
	Service	5,7,11	5,11	5,11
	Food safety	5,7,11	5,11	5,11
	Trust	7	5,7,11	7	Level III
	SAP(supplier audit performance)	5,7	5,7,11	5,7	Level III
	Responsibility	5	5,7,11	5	Level III
	Delivery	5	5,7,11	5	Level III
	Flexibility	5,7,11	5,11	5,11
Iteration IV	Halal Certification	11	11	11	Level IV
	Service	11	11	11	Level IV
	Food safety	11	11	11	Level IV
	Flexibility	11	11	11	Level IV

Table 6. Level partition criteria for halal suppliers

Criteria	Leve
Quality	Level I
Cost	Level II
Traceability	Level II
Trust	Level III
SAP (supplier audit performance)	Level III
Responsibility	Level III
Delivery	Level III
Halal certification	Level IV
Service	Level IV
Food safety	Level IV
Flexibility	Level IV

Table 6 shows the order of level rankings for each criterion based on the partition results in Table 5. For example, the quality criterion occupies the level I position, while cost and traceability criteria occupy a position just below the top level. Likewise, other factors are placed in the hierarchy according to their level placement until the lowest factor; level IV is the lowest level occupied by the criteria for halal certification, service, food safety, and flexibility. Table 7 shows that the drive power factor is obtained by adding up the numbers in the row, while the dependence power is obtained by adding up the numbers in the column. Driving power and dependence power are used as inputs in making MICMAC diagrams.

Table 7. Driving-power and dependence-power

Criteria	11	10	9	8	7	6	5	4	3	2	1
Driving Power	8	5	5	8	4	10	10	10	8	5	6
Dependence Power	4	9	9	8	6	7	7	7	7	9	7

4.4. Building ISM model

The ISM model is built using input from the FRM according to the partition level. The ISM model in this study has four hierarchical levels from level I to level IV. In Figure 5, the criteria for food safety, service, flexibility, and halal certification are placed at the bottom of the ISM model. This reflects that the four criteria for halal suppliers are the most critical factors that can affect the impact of the remaining seven criteria. In addition, these criteria strongly influence the criteria in the level III position, including the criteria for responsibility, delivery, trust, and SAP (supplier audit performance). The four criteria at level III directly influence the criteria at level II, namely, the responsibility criteria and SAP influence, supporting the criteria for traceability and cost. Level I is the topmost position, namely the quality criteria. All the criteria influence this criterion in deciding on the halal supplier criteria in the position below it.

Figure 5. ISM-based Supplier Criteria Hierarchy Model.

Based on Figure 5. Of the eleven criteria for halal suppliers, interrelated criteria oriented towards determining halal suppliers, such as food safety criteria, flexibility, service, and halal certification, are new and have not been widely used in determining halal suppliers. This is in line with previous studies stating that halal and food safety are essential findings. In addition, this shows the company’s perception of risk related to halal in a country where most of the population is Muslim (Başaran & Çakir, 2021).

4.5. Micmac

MICMAC (“Matrice d’Impacts Croisé Multiplication Appliquée un Classement”) aims to understand better the relationship between criteria for halal suppliers in the supply chain. This study resulted in eleven criteria for halal suppliers classified into four categories, namely (a) quadrant autonomous, (b) quadrant dependent, (c) quadrant linkage (d) quadrant independent; more details can be seen in Figure 6. Graphs represent MICMAC analysis through the dependent variable power is depicted on the x-axis while the drive power variable is located on the y-axis, which would be explained in the following section:

1. The autonomous quadrant is a quadrant located in the first order (quadrant I) with weak drive power and low dependence. The factors are relatively disconnected from the system, so they have little impact on the system. These factors have few links but may be very strong. In this study, there were no criteria for halal suppliers included in quadrant I (Autonomous). This shows that the eleven halal supplier criteria produced highly influence each other. In addition, these eleven criteria play an important role in determining halal suppliers.

2. Dependent quadrant: this quadrant is located in quadrant II which has low drive power but high dependence. The criteria in quadrant II consist of four criteria: trust, responsibility, cost, and delivery.

3. Quadrant Linkage: the criteria in this quadrant III have a strong drive power and high dependence known as the Linkage factor. These factors are unstable; any action on these factors would affect the others and have a feedback effect on the factor itself. Therefore, the criteria in this position should be studied carefully because the relationship between the criteria is not stable. This means that every action on these criteria would impact other criteria. The criteria for halal suppliers in quadrant III are more numerous than those in quadrants II and IV. In this quadrant, there are nine criteria, including six position criteria located in quadrant III, which include food safety, service, halal certification, traceability, SAP, and quality. At the same time, the other three criteria, such as responsibility, cost, and delivery, are located between the upper limit of quadrant II and the lower limit of quadrant III.

4. Independent Quadrant. The flexibility criteria are included in the in-independent variable category, which has a strong drive power but weak dependence. This quadrant can act as an external factor. The criteria in this quadrant would impact internal variables (linkage variables), which would later support the trust criteria as the dependent variable.

Figure 6. MICMAC analysis.

4.6. Analysis of the relationship between halal supplier criteria based on graph and MICMAC

Based on the MICMAC analysis, the quality criteria are in the linkage quadrant position; similar to the previous study, Tham et al. (2020) produced quality criteria in the linkage quadrant. The quality criterion is the most important and often used in assessing suppliers. Although in the selection of halal suppliers, quality criteria are often used because, according to S. Khan et al. (2021), the main risk in halal suppliers is quality problems. However, in reality, the quality of halal raw materials suppliers is deficient, and complete information about raw materials is not available. Therefore, a failure to supply raw materials would threaten the halal supply chain (M. H. Ali & Suleiman, 2018). Thus the quality criteria in halal suppliers hold the highest priority (S. Khan et al., 2022). This is in line with Figure 5 where the quality criterion occupies level one.

The criteria at level two are cost and traceability. The cost criteria show all expenses related to materials supplied by suppliers, including material costs, shipping costs, and after-sales costs (Taherdoost & Brard, 2019). While the cost criteria in halal suppliers have the perception that the cost of halal raw materials is higher than the cost of non-halal (Ali, Tan, et al., 2017; Masudin, Fernanda, et al., 2020; Soon et al., 2017). This gives suppliers a foothold in demanding higher costs for halal raw materials (S. Zailani et al., 2020) and becomes an obstacle for suppliers in providing halal raw materials at the exact cost (S. Khan et al., 2022) and becomes an obstacle for suppliers providing halal raw materials at the exact cost (S. Khan et al., 2022). Thus the cost criterion is considered an essential part of evaluating halal suppliers. This is in line with the results of the MICMAC analysis, which shows that the position of the cost criteria lies between linkage and independent, which means that the cost criterion has strong driving power and strong and weak dependent power. In addition, this cost criterion exists to influence other criteria, such as quality and traceability. In other words, the cost criterion is a trade-off between product costs and quality that can improve the halal supply chain’s integrity, as seen in Figure 6

Traceability criteria are at level two, which is in the linkage quadrant. Therefore, any action on the traceability criterion would impact other criteria that have a feedback effect. Azmi et al. (2021) support this recommendation that the cost criteria would significantly improve traceability-based management efforts. On the other hand, traceability systems that adopt advanced technologies such as blockchain can be expensive (Khan et al., 2021). However, proper traceability management can improve quality. This is evidenced by the exploration results of Besaran et al. (2021), confirming that traceability criteria for halal suppliers are essential in securing product halalness. Besides that, producers can find out information related to halal standards and track the quality of halal products, whether the products sent or stored are in accordance with halal standards (Dahlan et al., 2017).

The third level consists of trust, responsibility, delivery, and SAP (Figure 5). These four criteria are divided into two parts (responsibility and SAP), which are in the linkage quadrant. At the same time, the trust and delivery criteria are located in the dependent quadrant, which can be seen in Figure 6. The trust criteria have an essential role in sharing information among halal food supply chain members, in which the willingness to share information depends on trust (Masrom et al., 2017). Trust is the primary support for the members of the halal food supply chain (Rahman et al., 2021). Therefore, trust can be built through personal relationships and long-term cooperation involving honesty. However, the findings show that most cases of halal-certified food producers have low communication with their suppliers (Masrom et al., 2017). Thus, the trust criteria need to be considered in evaluating halal suppliers. Based on Figure 5, the trust criteria affect responsibility. This is in line with Nasihah’s statement (2020) that the law places the responsibility on suppliers or producers to ensure that they provide halal products as stated in the law. Responsibility is one of the new criteria introduced to the literature in evaluating suppliers (Banaeian et al., 2018). Likewise, in the opinion of El Mokadem (2017), delivery criteria include one of the main criteria in selecting suppliers. Başaran and Çakir (2021) explored delivery criteria for halal suppliers, including delivery volume, timely delivery schedule, delivery speed, meeting demand despite changes in delivery requirements, and delivery vehicle conditions. The position of the delivery criteria lies in the dependent quadrant, where according to Mandal and Deshmukh (1994), this criterion is vital in supplier selection. The same opinion was conveyed by Tham et al. (2020) that criteria that have high dependency strength must be involved in supplier selection.

The SAP (supplier audit performance) criteria aim to provide a halal assurance system and food safety by verifying the correctness of certified products through audits, laboratory analysis, and monitoring mechanisms (van der Spiegel et al., 2012). Therefore, it is the responsibility of the supplier to provide halal products. Thus, the responsibility criteria are essential for halal suppliers. This is in line with Figure 6, of the results of the MICMAC analysis that the SAP and responsibility criteria have high strength and this criterion has the strength of dependence, so it is necessary to be careful because these actions can affect other criteria (Kannan & Haq, 2007).

Level four consists of food safety, service, and halal certification criteria, which are in quadrant three linkages, while the criteria for flexibility lies in quadrant four independent. The three criteria in the linkage quadrant have solid relationships and linkages and are considered essential criteria in halal products (Başaran & Çakir, 2021). This aims to convince consumers that the products they consume are religiously safe, especially in a country where most of the population is Muslim. However, the fact is that there are suppliers who supply halal products that have not met the halal certification (S. Khan et al., 2021). This shows the inadequacy of standards and regulations (van der Spiegel et al., 2012). Therefore, the role of flexibility criteria in determining halal suppliers can quickly renew halal certification. Thus, the flexibility criterion is the key to achieving a halal assurance system by seriously responding to halal requirements.

5. Discussion

The discussion section reviews the research results and compares them with the results of previous studies, then describes the findings. In addition, the discussion section offers suggestions for further research and considers the practical implications of the findings found in the research.

5.1. Analysis of the relationship between ISM and MICMAC

According to Luthra et al. (2017) the performance of the supply chain is highly dependent on suppliers, where determining the proper criteria is a significant challenge in the supplier evaluation process. Basically, the criteria often adopted in evaluating suppliers of non-halal products are quality, cost, and delivery. However, the three criteria that occupy the top two in evaluating halal suppliers are quality and cost This is in line with Osmanovic et al. (2022) who argued that most product quality is determined by the quality of the supplier’s raw materials. Poor supplier selection can lead to unnecessary wastage of resources and increased production costs.

There are differences in costs for suppliers of halal and non-halal products, where suppliers would demand higher costs for halal raw materials (S. H. M. Zailani et al., 2010). Based on the results of the ISM hierarchy, the cost criteria are located one level below the quality criteria, which means that cost affects quality and costs. This is in line with Figure 6 of the MICMAC analysis, where the position of the quality criteria lies in the linkage while the cost position is between the linkage’s lower limit and the dependent’s upper limit. This is in line with A. U. Khan and Ali (2021) view that in evaluating suppliers, they prioritize quality criteria over cost. However, the quality and cost criteria are included in the criteria used in evaluating suppliers for both halal and non-halal products. In addition to cost, traceability criteria affect quality, as shown in Figure 5. Traceability in halal suppliers ensures supplier activity transparency in ensuring halal raw materials (León Bravo et al., 2021). Thus, traceability is influential in evaluating halal suppliers, emphasizing that it is free from malpractices of halal products, including handling, storage, and transportation.

Criteria located at level 3 and quadrant 3 Linkage act as criteria that would impact other criteria. Through continuous assessment and monitoring, SAP criteria can ensure supplier compliance in meeting halal requirements. Meanwhile, the responsibility criterion is the supplier’s responsibility in providing halal products. Although however, only a few researchers consider this criterion for evaluating halal suppliers. Based on a literature review of 38 papers on halal supplier selection, 8% consider the SAP criteria and 5% for the responsibility criteria. While researchers consider the halal certification criteria 10%, this criterion is slightly more adopted in choosing suppliers. However, the relationship between these three criteria is vital in determining halal suppliers. This is because every supplier who supplies halal products must show halal certification as a guarantee that the raw materials sent are truly halal (Ali, Zhan, et al., 2017; Soon et al., 2017) so that the resulting products are guaranteed to be halal.

Other criteria for halal suppliers include food safety, trust, delivery, service, and flexibility. The food safety perspective in selecting halal suppliers is related to guaranteeing safe food quality for consumption and does not endanger the health of ISO consumers (Neio Demirci et al., 2016). On the other hand, the trust criterion has not been popularly adopted in supplier selection, even though trust in halal suppliers is related to the supplier’s attitude towards the agreed halal commitment. However, trust criteria must be considered when selecting suppliers to avoid the risk of supplier fraud in replacing halal raw materials. As the results of research by S. Khan et al. (2021) indicated that the risks that occur to suppliers are due to the risk of using materials that violate the law and the risk of impure and unhygienic raw materials for the production of halal products. Because the MICMAC analysis shows that trust criteria are affected by food safety, and trust affects responsibility. For this reason, service and flexibility criteria for halal suppliers can quickly respond to government regulations in fulfilling halal certification obligations and quickly renew Halal certification. In addition, suppliers can adapt to implementing Islamic business ethics (Ismaeel & Blaim, 2012).

According to Mohd Riza et al. (2022), some of the causes of the inadequate response to the fulfillment of halal certification are due to the lack of awareness of halal industrial entrepreneurs applying for halal certification, who are of the view that halal certificates are not mandatory. While the research results of Nurhayati et al. (2022) stated that 87.79% of halal producers knew the importance of halal certification, only 16.07% had halal certification. This indicates that halal compliance with government regulations regarding halal product guarantees is still low. This phenomenon requires responsibility to ensure the halalness of the product. As stated by Mohd Riza et al. (2022), the responsibility for ensuring the halalness of food must be carried out by all levels, one of which is the supplier. At the same time, the government has the responsibility to make special laws regarding halal food. The opinion of previous researchers is in line with the results of this study on the ISM model. Figure 5 shows that there is a relationship between responsibility and flexibility.

5.2. Flexibility criteria relationship model to halal supplier criteria

Figure 7, the result of ISM and MICMAC represented in the Causal Loop Diagram, is used to visualize how the flexibility criteria are related to the criteria for other halal suppliers. Each criterion in the diagram describes a cause-and-effect relationship characterized by positive and negative relationships. A positive relationship indicates growth, while a negative relationship indicates a decrease. This causal loop diagram would help understand how each criterion of a halal supplier relates to other criteria, ultimately determining the effect of the flexibility criteria on the ten other halal supplier criteria. In Figure 7, there are two closed loops an amplifier loop and a balancing loop.

Figure 7. Causal Loop diagram of the flexibility relationship to halal suppliers.

The relationship between flexibility and halal certification in halal suppliers tends to be supplier flexibility in carrying out regulatory changes to halal products. The more flexible it causes, the number of halal certifications increases. This affects SAP (supplier audit performance) because, with the increase in halal certification, supplier performance audits will often be carried out to build a monitoring mechanism in making a significant contribution to the halal assurance system and food safety (Başaran & Çakir, 2021). This effect is based on van der Spiegel et al. (2012) statement that most halal assurances are based on certificates verified by auditing documents and documentation. One of the requirements needed in the audit process is traceability. Thus, the increasing number of audits causes the need for traceability also to increase. Traceability can facilitate the company’s halal auditor team in an administrative system that can track material purchases, ingredient formulations, incoming raw materials, material handling, selection, and storage (Novianti et al., 2022). In addition, increasing traceability would have an impact on cost and quality. The better the traceability system, the higher the cost. This is because, with a more comprehensive traceability system equipped with computers and barcodes, the software is needed for electronic data collection to replace paper-based traceability systems, such as the technology that is currently popular, namely blockchain technology (Alamsyah et al., 2022). According to H.-C. Chen et al. (2022), the role of blockchain technology in traceability systems can increase trust relationships in supply chain networks through decentralization. The traceability system impacts cost and quality because the traceability system for raw materials is used to identify data about raw material suppliers that can be used to ensure product quality and safety.

The flexibility criteria for service criteria are more focused on the supplier’s ability to meet product order changes, product changes, payment terms, ease of communication and transparency, the existence of guarantee policies and bilateral contracts (Başaran & Çakir, 2021), and responsive to halal certification renewals (Fujiwara & Ismail, 2018). Thus, the more flexible the service level to producers is high. Therefore, the increase in food safety is influenced by two criteria: high service and flexibility. According to Ali, Tan, et al. (2017), service criteria in suppliers are part of integrity in the food supply chain. This causes an increase in service, which would affect food safety in the form of food protection from physical, chemical, and biological hazards in the food supply chain (Başaran & Çakir, 2021). On the other hand, service improvement is influenced by responsibility in providing halal products. When food safety and flexibility increase the impact on high trust, this implies that people believe food safety is essential for public health and is a daily concern for everyone. Therefore, when trust increases, the responsibility of suppliers to ensure food safety and halal would increase. A high level of traceability accompanies increased responsibility in providing halal products. A better traceability system is a form of supplier responsibility toward fulfilling potential food safety (Sun & Wang, 2019). Increased supplier responsibility not only impacts traceability but also increases service. Considering the Flexibility criteria with delivery lies in the ability to meet buyer requests in terms of deliveries that are in accordance with halal requirements, products are free of contamination with non-halal products (Fujiwara, 2017).

Thus, there is a causal relationship between flexibility, delivery, responsibility, and traceability criteria. This relationship can be observed in the halal food supply chain. The more flexible the distribution of halal products, the freer contamination of non-halal products. As shipments increase, supplier liability increases the risk of non-halal products during shipping. High supplier responsibility has an impact on increasing supplier traceability in providing transparency in the halal assurance system. When traceability is improved, it can reduce recall costs, sales losses, damage to the company’s reputation, and government compensation costs (Barraood et al., 2022; Sun & Wang, 2019). In Figure 5, there are two reinforcing loops and a balancing loop. They are reinforcing circle links responsibility-service-food safety-trust. At the same time, the balancing loop connects the traceability cost. The four criteria should be paid more attention to reinforcing loops because policymakers can use them. Stakeholders should focus more on reinforcing loops because they are more helpful in making policy (Jayalath & Perera, 2021). Meanwhile, the balancing loop shows a robust traceability system, and costs would go down. This loop can stabilize the system towards equilibrium (Nair & Anbuudayasankar, 2016).

5.3. Theoretical contribution and implications

This research contributes to the literature on halal suppliers both theoretically and empirically. According to the results of this study, there are similar criteria for halal and non-halal suppliers, namely quality, cost, service, and delivery. These criteria are most commonly used to evaluate suppliers to satisfy customers. However, along with the proliferation of halal products that are increasingly in demand by consumers, the halal industry is required to meet the needs of halal products according to Islamic law, starting from suppliers, production, distribution, storage, and other processes (Feng, 2017). Therefore, this study’s results indicate differences in determining the criteria for halal suppliers with non-halal supplier criteria. The main criteria for halal suppliers are in the linkage cluster: quality, food safety, service, halal certification, supplier performance audit, and traceability. Although, based on previous similar research, there are differences in determining the criteria for halal suppliers, Başaran and Çakir (2021) placed the criteria for traceability and halal certification in the sub-criteria, while in the results of this study, the two criteria are the main criteria. This is because the traceability criteria play a role in tracking the halalness of products and product ingredients to guarantee halal authenticity, which is more transparent and accountable (Zainuddin et al., 2020). In addition, the traceability system is a requirement in the halal assurance system. At the same time, the criteria for halal certification are located to ensure that the raw materials supplied are guaranteed to be halal according to Islamic law.

So far, no study has used flexibility criteria to evaluate halal suppliers. However, in evaluating non-halal suppliers, several researchers use these criteria, including (Tham et al., 2020). The flexibility criterion measures the supplier’s ability to change schedules when there are unwanted problems. Meanwhile, Manders et al. (2016) considered that flexibility was used to measure the ability of suppliers to respond to changes in requirements in terms of location and delivery date and to respond to changing needs in ordering, shipping, and receiving goods supplied. Meanwhile, flexibility in halal suppliers serves to meet policy changes related to halal. In addition, the flexibility criteria owned by halal suppliers can effectively adapt to changes in policy on halal food. Thus there is a difference between halal flexibility and flexibility that does not consider halal. Halal flexibility focuses on the ability to respond by renewing halal certification (Fujiwara & Ismail, 2018) and adapting to implementing Islamic business ethics (Ismaeel, 2019).

The managerial implications of this research provide insight and recommendations to the halal industry, halal council, and the government to adopt the criteria that are important in evaluating halal suppliers. From the perspective of halal certification, the findings of this study indicate that halal certification is the most considered criterion for customers to select their suppliers. The government and the halal council should enhance the halal industry to obtain halal certification for their processes and products. The government regulations regarding the obligation of halal certification should be released. Pratama et al. (2023) showed that halal certification regulation would increase customers’ trust in purchasing products. Another study by Yuniarti et al. (2023) also revealed that regulation plays a significant role in halal food integrity, including halal certification. The findings of this study also show that flexibility is the most criterion considered in evaluating supplier selection. Vahabzadeh Najafi et al. (2020) stated that the flexibility criteria is the ability to withstand market changes. Suppliers of halal products should understand that uncertainties may affect their business processes. Noorliza (2021) indicated that suppliers should be flexible in aligning their resource capability strategically to suit the changing halal market and customer demands, such as the changing halal standard, halal regulation, and halal certification. Another study by Hashemi et al. (2022) revealed that halal suppliers should be more flexible in adapting to environmental changes due to their size and management structure.

6. Conclusion

The relationship between the flexibility and halal supplier criteria is analyzed in this study to identify the ones with a strong relationship with the flexibility criteria. Based on the results of the hybrid method approach (ISM-MICMAC-System Dynamics), the flexibility criterion is a criterion that can influence other criteria. This is evident from the results of the ISM method on the hierarchy of flexibility criteria located at level four, meaning that these criteria include critical criteria as essential in influencing the criteria for other halal suppliers located at level three, level two, and level one. Quality criteria at Level 1 are the main criteria in selecting suppliers. The following criteria are cost and traceability criteria. Although the flexibility criteria are not the main criteria in selecting suppliers, based on the MICMAC approach, the flexibility criteria are the only criteria in the independent quadrant. The independent quadrant functions as an independent variable. It has a strong driving force for the linkage quadrant: responsibility, delivery, supplier audit performance, food safety, service, cost, halal certification, quality, and traceability.

A causal loop diagram represents the relationship between eleven halal supplier criteria. There are two amplifier loops and a balancing loop. The reinforcing loop consists of responsibility-service-food safety-trust criteria. These four criteria can be used as input in making policy because the reinforcing loop shows the relationship between one criterion and another. If the influencing criteria increase, the affected criteria would also increase. Although stakeholders focus on reinforcing loops because they can be used for decision-making, the criteria classified as reinforcing loops are influenced by flexibility criteria. This indicates that the flexibility criteria have a relationship and impact that can affect the criteria for other halal suppliers.

For further research, further empirical studies can be involved to test and validate the developed model. In addition, future research can also consider the use of blockchain technology in strengthening aspects of supplier flexibility in the halal food supply chain. By using blockchain technology, manufacturers can monitor suppliers’ compliance with halal requirements in real time and can take appropriate action in case of violations. This could increase supplier flexibility in the halal food supply chain and strengthen consumer confidence in halal products produced by producers. Therefore, the use of blockchain technology in the halal food supply chain can be an interesting and relevant research topic to be deepened in the future

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Dwi Iryaning Handayani

Dwi Iryaning Handayani is a senior lecturer at Industrial Engineering Department, University of Panca Marga Probolinggo, Indonesia. Her research interests are logistics and supply chain modeling.

Ilyas Masudin

Ilyas Masudin is Professor of logistics and supply chain at Industrial Engineering Department, University of Muhammadiyah Malang, Indonesia. His research interests include logistics and supply chain

Aries Susanty

Aries Susanty is Professor in the field of Industrial Engineering and also a lecturer at Department of Industrial Engineering, Diponegoro University, Semarang, Indonesia. She has established an overarching research area in supply chain modeling, supply chain governance, halal supply chain, procurement and logistics strategy, and organization behavior.

Ika Deefi Anna

Ika Deefi Anna is a senior lecturer at Department of Industrial Engineering, Engineering Faculty, Universitas Trunojoyo Madura, Indonesia.