Quality evaluation of snack bars prepared using different proportions of Khudri dates and fried green lentil (Lens culinaris Medik.)

Abstract

The current study aimed to determine the impact of adding fried green lentil powder (FGLP) into date paste on the nutritive and sensory aspects of date bars. Date paste was partially substituted by 0.0, 2.5, 5.0, 7.5, 10.0, and 12.5% FGLP. DSB samples enriched with 10.0 and 12.5% FGLP exhibited the highest amounts of protein (4.78 and 5.36/100 g, respectively). Total fat content was 2.2, 2.08, and 1.94 times greater in DSB samples fortified with 12.5, 10.0, and 7.5% FGLP, respectively, than in the control sample. The highest ash levels (3.06, 3.11, and 3.14/100 g, respectively) were found in DSB samples that were enriched with FGLP at 7.5, 10, and 12.5%. The crude fiber content of FGLP-fortified date samples jumped significantly, from 10.10 g/100 g for the control sample to 11.16, 11.45, and 11.74 g/100 g for date bar samples fortified with 5.0, 7.5, 10.0, and 12.5% FGLP. Compared to the control sample, the carbohydrate content of date bars significantly decreased when FGLP was added. Date bars supplemented with 12.5% FGLP covered the isoleucine, leucine, lysine, total sulfur amino acids, total aromatic amino acids, threonine, and valine needs by 78.20, 100.00, 55.10, 70.40, 91.70, 46.1, and 67.7%, respectively. The content of saturated fatty acids decreased as FGLP inclusion levels increased. The mineral concentration of Mg, P, Mn, Cu, Fe, and Zn in supplemented date bars increased significantly as the FGLP replacement amount increased. Overall acceptability was not statistically different among all date bars containing up to 7.5% FGLP.

PUBLIC INTEREST STATEMENT

Fresh fruits possess a high carbohydrate, mineral, vitamin, dietary fiber, as well as energy content. Fruit bars, on the other hand, tend to be more attractive among consumers than fresh fruits since they provide more balanced nutrients. Fortification of date bars with various levels of fried green lentil powder (FGLP) improved the nutritional and sensory properties of the produced date bars.

Keywords:

• Food intake
• antioxidant
• public health
• diet supplementation
• fatty acid

REVIEWING EDITOR:

• M. Luisa Escudero-Gilete, Universidad de Sevilla, Spain

SUBJECTS:

• Agriculture & Environmental Sciences; Biochemistry; Nutrition; Food Additives & Ingredients

1. Introduction

A nutritious bar is described as a type of nutritional food supplement in the shape of a bar that contains carbohydrates, protein, lipids, vitamins, and minerals and serves as a source of energy (Rajabi, 2017). As defined by the Food and Drug Administration, Caloric bars are food supplements that athletes and other physically demanding individuals typically use to meet their calorific demands (Amira et al., 2020).

Date fruits contain considerable quantities of total sugar (44–88%), protein (2.3–5.6%), lipids (0.2–0.5%), minerals, and other nutrients, as well as a high level of dietary fiber (6.4–11.5%). Dates are an excellent source of carbohydrates in the form of sugars, which account for ∼78% of the total weight of the fruit, however, they are poor in protein and fat (Alhomaid et al., 2022). Fresh dates provide close to 157 calories per 100 g of flesh, whereas dates that have been dried provide ∼300 calories per 100 g (Habib et al., 2014). Date fruits can be consumed in their natural state or dehydrated as well as processed into products, such as date paste and syrup (Tang et al., 2013). Additionally, they showed that dates have significant antioxidant, anti-inflammatory, gastrointestinal-protection, and tumor-prevention capabilities (Tang et al., 2013). Animal research revealed that Aseel dates had anti-hyperglycemic properties (Ahmed et al., 2017). Due to the large quantity of 13 phenolic compounds, dates fruit was discovered to be a particular inhibitor of -glucosidase and to decrease plasma sugar more than Acarbose (which is a medicine that is often used to treat type 2 diabetes mellitus) after 30 min of intake (El Abed et al., 2017). Additionally, it has been demonstrated to be useful in the prevention of Type 2 diabetes and a variety of other health issues (Chaari et al., 2020). Date fruit is widely used as a nutritional ingredient in bread, cookies, jellies, preserves, jams, juice, sweets, fruit smoothies, grain products, a vinegar-based as well as ice cream (El Hadrami & Al-Khayri, 2012). Mixing date flesh with other high-nutritional-value natural products may improve and enhance the nutritional attributes of the finished products (Aljaloud et al., 2020). Fruit bars are a highly valuable product in terms of handling process as well as delicious and easy-to-eat a food item that can be consumed delivered anywhere. As a result, processing fruits into fruit bars or fruit leather is particularly desirable as fully ripe fruits with higher sugar, improved color, flavor, and carotenoid content, as well as harvested and over-ripe fruits can be employed (Tiwari, 2019). These bars may contain a variety of fruits, grains, and legumes as an important ingredient (Alhomaid et al., 2022). To improve the nutritional and functional properties of date bars, different trials are carried out, for which numerous innovative components are used, including roasted chickpea, roasted white oat, skim milk, and dark chocolate (Ur Rehman et al., 2020), almonds, sesame seeds, oat flakes and skim milk powder (Al-Hooti et al., 1997) and germinated flax seed powder (Alhomaid et al., 2022).

In this regard, Lentil (Lens culinaris Medik.), is one of the most important legume crops The plants are grown for their small lens-shaped seeds, which are high in protein (35–40%) and carbohydrates, as well as calcium, phosphorus, iron, and B vitamins (Giannakoula et al., 2012). Lentil seeds contain amino acid compositions that can improve the nutritional properties of cereal based products. These seeds also contain a large number of bioactive substances including fibers and phytochemicals, particularly phenolic compounds (Giannakoula et al., 2012; Khazaei et al., 2019). Lentils are known to come in different colors, including yellow, orange, red, green, brown, and black, based on the variety and the composition of the seed coats and cotyledons. Lentils are classified into two commercial market classes: red (based on the cotyledon colour of dehulled seeds) and green (based on seed coat colour) (Khazaei et al., 2019). Lentil-based ingredients are incorporated into a wide range of products, such as snack foods, flour mixes/doughs, ready-to-eat soups, baked items, gluten-free products, as well as ethnic cuisines (Dhull et al., 2022). According to Oduro-Yeboah et al. (2022), dehulled whole red lentils have an important trading class in India, Bangladesh, and Nepal, however dehulled and split red lentils are extremely common in different South-Asian and Middle-East countries. Various thermal and non-thermal treatments, such as cooking, autoclaving, boiling, extrusion, baking, roasting, germination, and fermentation techniques, are required to reduce or eliminate ant nutritional components, such as lectins, phytate, and enzyme inhibitors, which have been shown to limit protein digestibility and nutrient absorption (Dhull et al., 2022; Patterson et al., 2017). The characteristics of date bars fortified with fried green lentil powder (FGLP) have not yet been assessed. Therefore, the objective of the present investigation was to determine the benefits of incorporation of different levels of fried whole green lentils powder (FGLP) into date paste on the nutritional and sensory aspects of date snack bars.

2. Materials and methods

2.1. Materials

Ten kilograms of Khudri Dates (Phoenix dactylifera L.) paste (KDP) were purchased from AlWatania supermarket, Awthal, Qassim, Saudi Arabia. GL Olive oil for the frying process was obtained from Tamimi Markets, Buraydah, Qassim, Saudi Arabia.

All chemicals used for chemical analysis were of analytical grade and had been used exactly as they were supplied, with no further purification, and were obtained from Sigma-Aldrich Chemical Co. in the United Kingdom.

2.2. Methods

2.2.1. Preparation of fried whole green lentils powder (FGLP)

Green lentils were steamed in a steamer at 121 °C for 15 min at a pressure of 1.5 lb/in² and dried in an electric air draught oven at 50 °C for 24 h. The steamed dried lentils were fried in olive oil for 3 min. The fried lentils were ground in an electric mill (Braun Model 1021, Blender, 600.0 W JB1023-WH), passed through a 150-m mesh sieve, and stored in glass jars at 4 ± 1 °C for further evaluations.

2.2.2. The recipe for date fruit snack bars (DSB)

Khudri Dates paste (KDP) was partially replaced by 0, 2.5, 5.0, 7.5, 10.0, and 12.5% of FGLP. The produced mixture was formed into bars ∼2.0 cm wide, 0.5 cm high, and 4 cm length. DSB had been kept in a cold container at 20 °C for 3 h before sensory evaluation. The cold bars were wrapped in aluminum foil and packed in polyethylene bags. DSB was stored at −18 °C for additional evaluation (as shown in the following diagram).

2.2.3. Determination of proximate composition and energy value DSB

Moisture content, protein content, ash, crude fiber, and fat contents of DSB were assessed according to AOAC (2012, methods 925.09 B, 950.36, 930.22, 950.37, and 950.36, respectively). Carbohydrate content was calculated by differences. The caloric value was calculated according to the following equation (Ali et al., 2022). $$\begin{array}{l}\text{Energy}\hspace{0.17em}\left(\text{kcal}/100\hspace{0.17em}\text{g}\right)=[\left(9\hspace{0.17em}\times \text{lipids}\%\right)\hspace{0.17em}+\left(4\times \text{proteins}\%\right)\\ +\hspace{0.17em}\left(2\times \text{fiber}\%\right)+\hspace{0.17em}\left(4\times \text{carbohydrates}\hspace{0.17em}\%\right)]\end{array}$$

2.2.4. Determination of mineral content

Mineral elements were measured using atomic absorption spectroscopy (3300 Perkin–Elmer) as reported by Ali et al. (2022).

2.2.5. Amino acid determination and P-PER

The amino acid analyzer AAA400 (INGOS, Czech Republic) was used to assess the amino acid composition of samples using the protocols recommended by Mæhre et al. (2018). Ion-exchange liquid was used to determine amino acids. chromatography (Amino Acid Analyzer Model AAA-400, Ingos, Czech Republic) using post-column ninhydrin derivatization and a VIS detector. An inner glass column diameter of 3.7 mm and length of 350 mm was filled with a strong cation exchanger in the LG ANB sodium cycle (Laboratory of Spolchemie) with an average particle size of 12 µM and 8% porosity. Elution of the investigated amino acids has been evaluated at a column temperature of 74 °C. AVIS detector with two channels and a 5 mL inner cell volume L was programmed with two wavelengths: 440 and 570 nm. ninhydrin solution was produced in 75% v/v methyl cello solve and 2% v/v 4 M acetic buffer (pH 5.5). As a reducing agent, tin chloride (SnCl₂) was utilized. The produced ninhydrin solution was kept at 4 °C in an inert atmosphere (N₂). The flow rate was 0.25 mL min-1, and the temperature of the reactor was 120 °C.

P-PER = −0.468 + 0.454 leucine −0.105 tyrosine equation was used to calculate the predicted protein efficiency ratio (P-PER) (Adeyeye, 2009).

2.2.6. Fatty acid compositions

FAMEs were separated and calculated in accordance with the recommendations of IUPAC (1992a, 1992b). Capillary gas chromatography (HP 6890) was used to determine both the qualitative and quantitative fatty acids in the oil samples, which were given in relative area percentages. By integrating a solution of oil (ca. 0.1 g) in heptane (2 mL) with a solution of methanolic potassium hydroxide (0.2 mL, 2 N), fatty acids were trans esterified into their corresponding fatty acid methyl esters (FAMEs). A gas chromatograph equipped with a DB-23 capillary column (60 m× 0.32 mm × 0.25 m film thickness) and a flame ionization detector were used to identify the FAMEs. The flow rate of nitrogen was 3 mL/min, whereas the rates of hydrogen and air were 40 and 450 mL min⁻¹, respectively.

2.2.7. Sensory evaluation

The primary goal of the organoleptic evaluation was to determine how different quantities of fried whole green lentil powder (FGLP) affected the sensory aspects of date snack bars. The sensory properties of DSB were evaluated by 150 judges (aged 20–45 years) recruited at random from the College of Agriculture and Veterinary Medicine at Qassim University in Buraydah, Saudi Arabia, using a ten-point hedonic scale. Before the study started, the panelists provided informed, written permission. Panelists were invited to participate in a sensory evaluation training session for Check-All-That-Apply (CATA) products. A total of 18 h were spent training them over the course of three 6-h sessions. Panelists were given guidelines to ensure the reliability of the results before the sensory evaluation. Panelists were assigned seats in separate sensory booths and provided a bottle of drinking water to refresh their palates before evaluating each item. The appearance, flavor, taste, texture, color, and overall acceptance of the samples were graded on a ten-point hedonic scale (10—like extremely to 1—dislike seriously). Over the period of ten working days, the sensory evaluation was completed and recorded by fifteen judges on a daily basis. Following the recording process, all of the scores for each item were computed, and statistical software was used to determine the average of those assessments. The sensory evaluation complied with the standards for sensory research defined by the Auckland University of Technology Study’s Ethics Committee (AUTEC ethic application 16/340).

2.2.8. Statistical analysis

SPSS (version 20) was applied to analyze the results. The data were statistically examined in five replicates, excluding the sensory evaluation results (n = 150). The data were subjected to analysis of variance and means were separated using Duncan’s Multiple Range Test at 95% confidence level.

3. Results and discussion

3.1. Proximate composition of date paste and fried whole green lentils powder (FGLP)

Table 1 shows the chemical composition of date Paste and fried whole green lentils powder (FGLP). The proximate nutritional composition differed between date paste and FGLP. Date paste contained (19.73 g/100 g) moisture, whereas fried whole green lentils powder (FGLP) contained (4.16 g/100 g) of moisture (Table 1). The higher frying temperature (160 °C) is responsible for the lower moisture content of fried whole green lentils powder (FGLP). The low moisture quantity in FGLP may enhance its shelf-life stability through limiting the growth of mold, bacteria, insects, along with other biochemical processes which lead to deterioration during storage process (El Anany, 2015). Fried whole green lentils powder (FGLP) has high quantities of protein, ash, and fibers (28.77, 6.77, and 23.34 g/100 g, respectively). According to Grusak (2009), lentil seeds contain proteins (15.9% to 31.4 g/100 g), carbohydrates (43.4–74.9 g/100 g), lipid (0.3–3.5 g/100 g), total dietary fiber (5.1–26.6 g/100 g), as well as ash (2.2–6.4 g/100 g). According to these findings, FGLP can be employed as an important source of protein, minerals, and dietary fiber. Date paste comprises mainly from carbohydrates (84.10 ± 3.56 g/100 g DWB), with 10.10 g/100 g DWB of dietary fiber and modest amounts of protein (2.25 g/100 g DWB). Therefore, the addition of FGLP as a potential component could improve the nutritional benefits of the produced date bars when the date paste is substituted with different quantities of FGLP.

Table 1. Chemical composition of date paste and fried whole green lentils powder (FGLP).

Components (g/100 g dry weight basis)	Date paste	FGLP
Moisture	19.73^a ± 1.25	4.16^b ± 1.02
Fat	0.35^b ± 0.04	4.33^a ± 0.13
Ash	2.70^b ± 0.02	6.77^a ± 0.25
Protein	2.25^b ± 0.85	28.77^a ± 1.35
Dietary fibres	10.10^b ± 0.74	22.34^a ± 0.97
Carbohydrate	84.10^a ± 3.56	37.79^b ± 2.38
Energy (kcal/100 g)	370.55^a ± 3.51	305.21^b ± 3.87

Data are expressed as the mean ± standard deviation (n = 5).

Means in the same row followed by the same letter ^(a,b) are not significantly different.

3.2. Proximate composition and energy value DSB

Table 2 shows the proximate composition (g/100 g dry weight basis) and caloric value (kcal/100 g) of supplemented DSB samples. Moisture content is a measurement of the total amount of water in a food product that is usually expressed as the percentage of water by weight on a wet basis. Moisture level and water activity must be kept below 10% and 0.60–0.65, respectively, to prevent microbial growth (Mathlouthi, 2001; Mercer, 2008). The moisture content of DSB samples varied from 13.29 to 19.73 g/100 g. The control sample with no FGLP added had the greatest moisture content (19.73 g/100 g). The moisture content of the enriched DSB samples reduced significantly (p ≤ 0.05) as the FGLP replacement levels increased (19.73–13.29 g/100 g). The relatively low moisture content of the enriched DSB samples compared to the control (100% date paste) indicates that the DSB samples supplemented with FGLP would have a longer shelf life than the control bar samples. The high moisture content of dates provides a suitable matrix for blending with other cereal ingredients as the moisture is readily absorbed by these complementary ingredients and helps in extending product shelf life, especially in date bars (Ibrahim et al., 2021). The lipid content of the enriched DSB samples improved (0.35–0.77 g/100 g), as demonstrated in Table 2. Since fat improves palatability, the proportionate increase in fat content of the enriched DSB samples suggests that the enriched DSB samples would be significantly better in taste than the control sample (Drewnowski et al., 1992). The DSB with the highest fat content (0.77 g/100 g) had received FGLP at a 12.5% inclusion level. Meanwhile, the lowest value was recorded for control samples that weren’t composed of FGGP. In comparison with the control sample, total fat content was 2.2, 2.08, and 1.94 times higher in DSB samples fortified with 12.5, 10.0, and 7.5% FGLP, respectively (Table 1). Date fruit has a low fat content, with ∼0.14 g/100 g in fresh dates (kimri stage) and 0.38 g/100 g in dried dates (tamer stage). The lipids are primarily located in the outer layer and are more important in protecting the fruit rather than enhancing to the nutritional content of the date flesh (Lieb et al., 2020). Lentils have a low fat content and thus a low calorie level (USDA, 2010). Ryan et al., 2007 showed that lentil seeds had a total lipid content that was ∼1.40 g/100 g. However, the amount of lipids in deep-fried items increases due to oil absorption and retention, which indicates an increase in energy intake (USDA, 2013). As shown in Table 2, the protein content of the enriched DSB samples increased significantly (p ≤ 0.05) as the FGLP substitution level increased. DSB samples enriched with 10.0 and 12.50% FGLP exhibited significantly the highest amounts of protein (4.78 and 5.36 g/100 g, respectively), while the control sample (with no FGLP addition) possessed significantly the lowest protein level (2.25 g/100 g). The significantly higher protein concentration of the enhanced DSB samples could be attributable to FGLP’s high protein content. Like the seeds of other cultivated legumes, lentils are rich in protein. Lentil seeds possess around 26% crude protein as dry weight basis (Khazaei et al., 2019).

Table 2. Proximate composition (g/100 g dry weight basis) and energy content (kcal/100 g) of supplemented DSB samples.

Components (g/100 g dry weight basis)	DSB (KDP: FGLP %)
	100:0	97.5:2.5	95:5	92.5:7.5	90:10	87.5:12.5
Moisture	19.73^e ± 1.25	18.10^de ± 1.52	17.45^d ± 1.27	16.55^c ± 1.28	15.02^ab ± 1.58	13.29^a ± 1.28
Fat	0.35^a ± 0.04	0.59^b ± 0.04	0.64^c ± 0.05	0.68^cd ± 0.07	0.73^d ± 0.05	0.77^e ± 0.05
Ash	2.70^a ± 0.02	2.96^b ± 0.09	3.00^b ± 0.02	3.06^c ± 0.05	3.11^d ± 0.07	3.14^d ± 0.58
Protein	2.25^a ± 0.85	3.03^b± 0.82	3.61^c ± 0.06	4.20^d ± 0.57	4.78^e ± 0.87	5.36^f ± 0.89
Dietary fibres	10.10^a ± 0.74	10.59^b ± 1.04	10.88^bc ± 1.23	11.16^c ± 1.07	11.45^d ± 1.25	11.74^e ± 0.58
Carbohydrate	84.10^a ± 3.56	83.41^a ± 3.85	82.53^a ± 2.57	81.64^b ± 3.59	80.75^b ± 2.25	79.86^c ± 2.58
Energy (kcal/100 g)	370.55^a ± 3.55	370.10^a ± 2.63	369.46^a ± 2.76	368.81^b ± 3.96	368.17^b ± 3.74	367.52^c ± 2.58

Data are expressed as the mean ± standard deviation (n = 5).

Means in the same row followed by the same letter ^(a–f) are not significantly different.

As the FGLP replacement level increased, the ash content (2.70–3.14 g/100 g) of the supplemented DSB samples improved significantly (Table 2). The ash level in DSB samples enriched with FGLP at 7.5, 10, and 12.5% enrichment levels was the greatest (3.06, 3.11, and 3.14 g/100 g, respectively). The lowest value (2.70 g/100 g) was measured for control samples without the inclusion of FGLP. These increases in ash levels in supplemented date samples could be attributed to FGLP ash concentration. In the study by Zia-UL-Haq et al. (2011), lentil Seeds of NIAB Massor 2002 had the greatest ash content (5.72 g/100 g), whereas Massor 85 had the lowest (4.16 g/100 g). Dhull et al. (2022) reported that the ash content of lentils ranged from 2.2 to 6.4 g/100 g. The crude fiber content in DSB samples ranged from 10.10 to 11.74%. The crude fiber content of DSB samples supplemented with FGLP increased significantly (p ≤ 0.05) as the FGLP supplementation level increased. The crude fiber content of FGLP-fortified date samples increased significantly, from 10.10 g/100 g for the control sample with no FGLP inclusion to 10.59, 10.88, 11.16, 11.45, and 11.74 g/100 g for date bar samples supplemented with 2.5, 5.0, 7.5, 10.0, and 12.5% of FGLP, respectively. Lentils are a rich source of dietary fiber that ranges from 11.00 to 31.00 g/100 g in green and pink types, respectively (Dhull et al., 2022). Carbohydrate content ranged from 79.86 to 84.10 g/100 g in DSB samples. When date paste was replaced with FGLP, the carbohydrate content of supplemented DSB samples decreased significantly. The addition of 10 and 12.5% FGLP into date bars resulted in significant decreases (p ≤ 0.05) in carbohydrate content (80.75 and 79.86 g/100 g) as compared to the control sample (84.10 g/100 g). The higher protein and lower carbohydrate content of lentils compared to cereal grains may aid in expanding the application of lentils and lentil-based products in the development of novel items (Dhull et al., 2022).

The calorie values of 100 g of DSB samples ranged from 367.52 to 370.55 (kcal). The caloric values of DSB samples fortified with FGLP were significantly lower than those of the control samples without FGLP addition. The control sample with no FGLP addition had the highest caloric (370.55 kcal) value. At the same time, DSP samples enriched with 7.5, 10.0, and 12.5% FGLP gave the lowest caloric values (368.81, 368.17, and 367.52 kcal, respectively). Lentils possess a low amount of fat and consequently a low caloric level (USDA, 2010). Lentils Lentil-based recipes reduced the cumulative intake of energy by 8% when compared to a control meal (Mollard et al., 2012). This research supports the qualitative research studies that consistently indicate an adverse relationship between pulse intake and BMI or risk of obesity (McCrory et al., 2010).

3.3. Amino acid contents of control and supplemented date bars (g/100 g protein)

Table 3 shows the amino acid contents of control and supplemented date bars (g/100 g protein). Generally, the total essential amino acid content of enriched date bar samples was significantly greater compared to that of control bars (Table 3). The addition of different amounts of FGLP into date paste enhanced the levels of total sulfur amino acids, total aromatic amino acids, leucine, isoleucine, threonine, as well as valine. Although the incorporation of 12.5% of FGLP caused significant improvement in the amino acid profile of produced DSB samples, the improvement did not reach the value suggested by the FAO/WHO pattern (1991) for all essential amino acids except leucine. Date bars enriched with 12.5% FGLP fulfilled the requirements of isoleucine, leucine, lysine, total sulfur amino acids, total aromatic amino acids, threonine, and valine by 78.2, 100, 55.1, 70.4, 91.7, 46.1, and 67.7%, respectively. Aspartic acid (28.47–31.26), glutamic acid (28.23–31.41), arginine (4.06–4.69), proline (2.91–3.35), alanine (3.67–3.99), glycine (2.97–3.24), and serine (2.35–2.68) were the predominant non-essential amino acids in date bars enriched with different amounts of FGLP. The most abundant amino acids in dried dates were glutamic, aspartic, glycine, proline, and leucine (Al-Farsi & Lee, 2008). PER is a good marker to measure the nutritional value of proteins (El Anany, 2015). DSB samples had P-PER values that varied from 2.22 to 3.35. In general, the incorporation of FGLP into date paste enhanced the protein efficiency ratio compared to the control sample. The highest P-PER values of 2.34 and 2.35 were obtained for DSB samples supplemented with 10.0 and 12.5% FGLP powder, respectively. However, the control sample with no FGLP addition had the lowest PER value (2.22). PER levels <1.5 indicate low-quality protein, while PER values more than 2 indicate high-quality protein (Elamine et al., 2022).

Table 3. Amino acid contents of control and supplemented date bars (g/100 g protein).

Amino acid	DSB (KDP: FGLP %)
	100:0	97.5:2.5	95:5	92.5:7.5	90:10	87.5:12.5	FAO/WHO pattern (1991)
Isoleucine	1.75	2.00	2.05	2.10	2.15	2.19	2.80
Leucine	6.23	6.47	6.50	6.54	6.58	6.61	6.60
Lysine	2.4	2.72	2.84	2.96	3.08	3.20	5.80
Cystine	0.63	0.83	0.83	0.83	0.83	0.83	–
Methionine	0.73	0.93	0.93	0.93	0.93	0.93	–
Total sulfur amino acids	1.36	1.76	1.76	1.76	1.76	1.76	2.50
Tyrosine	1.29	1.54	1.59	1.63	1.68	1.73	–
Phenylalanine	3.77	3.99	4.00	4.02	4.03	4.05	–
Total aromatic amino acids	5.06	5.53	5.59	5.65	5.71	5.78	6.30
Threonine	1.15	1.39	1.44	1.48	1.53	1.57	3.40
Valine	1.85	2.11	2.18	2.24	2.31	2.37	3.50
Total essential amino acid	19.8	21.98	22.36	22.73	23.12	23.48	–
Histidine	1.57	1.79	1.81	1.83	1.85	1.87	1.90
Arginine	4.06	4.35	4.43	4.52	4.60	4.69	–
Aspartic acid	31.26	30.14	29.72	29.30	28.88	28.47	–
Glutamic acid	31.41	28.93	28.76	28.59	28.41	28.23	–
Serine	2.35	2.58	2.60	2.63	2.66	2.68	–
Proline	2.91	3.16	3.20	3.25	3.30	3.35	–
Glycine	2.97	3.18	3.20	3.21	3.22	3.24	–
Alanine	3.67	3.89	3.92	3.94	3.96	3.99	–
Total non-essential amino acids	78.5	78.02	77.64	77.27	72.92	76.52	–
PER	2.22	2.31	2.32	2.33	2.34	2.35	–

3.4. Fatty acid compositions of date bars fortified with different amounts of FGLP

The Fatty acid compositions of date bars fortified with different amounts of FGLP are shown in Table 4. The level of saturated fatty acids changed significantly among control and experimental, fortified date bars. With increasing FGLP inclusion levels, the content of saturated (SFA) fatty acids dropped significantly. The levels of myristic and palmitic acids in the enriched date bats formulated with FGLP were significantly decreased (p ≤ 0.05) compared to the control with no addition of FGLP. The results also revealed that the quantity of myristic and palmitic acids in date bars containing 12.5% FGLP was decreased (p ≤ 0.05) by 9.63 and 3.75%, respectively, when compared to control date bars with no FGLP. The inclusion of FGLP into date paste at various levels resulted in significant improvements in the content of mono-unsaturated fatty acids, which changed from 53.82% in unfortified date bars to 54.01 for date bars fortified with 12.5% GFSs. The oleic acid content followed the same pattern. Date bars supplemented and enriched with different levels of FGLP exhibited significant increases in polyunsaturated fatty acid content. When compared to control date bars, the poly-unsaturated fatty acid content in date bars enriched with 7.5, 10, and 12.5% FGLP was greater by 9.11, 11.65, and 14.12%, respectively.

Table 4. Fatty acid compositions (%) of date bars fortified with different amounts of FGLP.

Fatty acid	DSB (KDP: FGLP %)
	100:0	97.5:2.5	95:5	92.5:7.5	90:10	87.5:12.5
C 14:0 Myristic acid	6.85^a ± 0.08	6.88^a ± 0.98	6.71^b ± 0.87	6.53^c ± 1.05	6.36^d ± 1.02	6.19^e ± 0.87
C 16:0 Palmitic acid	25.55^a ± 1.54	25.52^a ± 1.25	25.29^b ± 1.74	25.06^c ± 1.87	24.83^d ± 1.87	24.59^de ± 1.65
C 16:1 Palmitoleic acid	ND	0.14^a ± 0.01	0.17^b ± 0.06	0.21^c ± 0.03	0.25^d ± 0.03	0.28^de ± 0.03
C 18:0 Stearic acid	ND	0.16^a ± 0.01	0.21^b ± 0.03	0.27^c ± 0.01	0.33^d ± 0.05	0.38^e ± 0.04
C 18:1 Oleic acid	53.82^a ± 2.35	53.98^a ± 2.74	53.94^a ± 2.98	53.90^a ± 2.65	53.87^a ± 1.98	53.83^a ± 2.54
C 18:2 Linoleic acid	13.38^a ± 1.23	13.86^b ± 1.42	14.14^c ± 1.87	14.41^d ± 1.74	14.69^de ± 1.52	14.97^e ± 1.05
C 18:3 Linolenic acid	ND	0.16^a ± 0.02	0.22^b ± 0.04	0.28^c ± 0.06	0.34^d ± 0.08	0.40^e ± 0.02
C 20:0 Arachidic acid	ND	0.11^a ± 0.01	0.12^b ± 0.02	0.13^b ± 0.04	0.14^cd ± 0.03	0.15^d ± 0.01
Saturated fatty acids	32.5^a ± 1.87	32.36^a ± 1.65	32.03^a ± 1.87	31.69^b ± 1.65	31.35^c ± 1.68	31.02^d ± 1.54
Monounsaturated fatty acids	53.82^a ± 2.98	54.02^b ± 3.01	54.02^b ± 2.61	54.01^b ± 3.07	54.01^b ± 3.06	54.01^b ± 2.58
Polyunsaturated fatty acids	13.38^a ± 1.54	13.92^b ± 1.28	14.26^c ± 1.98	14.60^d ± 1.03	14.94^e ± 1.05	15.27^f ± 1.54

ND: not detected.

Data are expressed as the mean ± standard deviation (n = 5).

Means in the same row followed by the same letter ^(a–f) are not significantly different.

As the FGLP replacement level increased, the quantity of C18:2 n-6 (Linoleic acid) in date bars increased significantly. The amount of C18:2 n-6 (Linoleic acid) in date bars fortified with FGLP increased dramatically, from a non-detectable level in the control sample without FGLP addition to 0.16, 0.22, 0.28, 0.34, and 0.40% in the samples fortified with 2.5, 5.0, 7.0, 10.0, and 12.5% of FGLP, respectively. Linoleic (46.81–49.11%), oleic (21.3–23.27%), palmitic (14.41–18.10%), and linolenic (8.20–11.25%) acids are the most prominent in lentil oil. These fatty acid ratios are believed to be critical to their nutritional value. Stearic, gadoleic, arachidic, erucic, and palmitooleic acids were also found in the collected lentil samples at 1.14–1.16, 0.43–0.66, 0.39–0.55, 0.15–0.16, and 0.08–0.15%, respectively (Gharibzahedi et al., 2012).

3.5. Mineral content of date bars fortified with various quantities of FGLP

Table 5 shows the mineral content of date bars fortified with various quantities of FGLP. The content of Mg, P, Mn, Cu, Fe, and Zn in supplemented date bars increased significantly as replacement levels increased (Table 5). The resultant finding might have been attributed to FGLP’s high mineral component composition. The highest concentrations of the above-mentioned micro- and micro elements were discovered in date bars fortified with 10 and 12.5% FGLP, respectively, whereas the lowest values were observed in control date bars without FGLP supplementation. Table 5 also illustrates that the levels of Mg, P, Mn, Cu, Fe, and Zn in date bars supplemented with 12.5% FGLP were ∼1.04, 1.77, 1.27, 1.90, 3.81, and 4.25 times higher, respectively, then in control date bars with no FGLP enrichment. Minerals have numerous of beneficial impacts on human health. Indeed, lentil is a valuable source of minerals, contributing to the food and nutritional security of millions of people, primarily in developing nations (Benayad & Aboussaleh, 2021).

Table 5. Mineral content (mg/100 g) of date bars fortified with various quantities of FGLP.

Elements	100:0	97.5:2.5	95:5	92.5:7.5	90:10	87.5:12.5
Na	5.37^a ± 0.89	5.25^b ± 0.56	5.12^c ± 0.87	4.98^d ± 0.54	4.85^e ± 0.58	4.71^f ± 0.68
Ca	62.91^a ± 3.25	62.58^b ± 2.74	62.23^c ± 3.27	61.88^d ± 2.57	61.54^e ± 2.57	61.19^f ± 2.51
K	1093.29^e ± 20.36	1085.25^d ± 15.26	1077.20^c ± 17.2	1069.14^bc ± 18.5	1061.08^b ± 16.2	1053.02^a ± 18.20
Mg	77.13^a ± 3.69	77.79^b ± 3.41	78.44^c ± 3.17	79.09^d ± 3.27	79.74^e ± 3.25	80.39^f ± 3.58
P	72.45^a ± 3.58	83.76^b ± 3.64	95.05^c ± 4.81	106.34^d ± 5.27	117.63^e ± 4.28	128.92^f ± 2.58
Mn	0.37^a ± 0.02	0.40^a ± 0.02	0.42^b ± 0.05	0.44^b ± 0.04	0.45^bc ± 0.03	0.47^c ± 0.05
Cu	0.11^a ± 0.01	0.15^b ± 0.01	0.16^b ± 0.03	0.18^b ± 0.01	0.20^c ± 0.01	0.21^c ± 0.03
Fe	0.22^a ± 0.02	0.36^b ± 0.04	0.48^c ± 0.02	0.60^d ± 0.02	0.72^e ± 0.08	0.84^f ± 0.03
Zn	0.12^a ± 0.01	0.22^b ± 0.03	0.29^c ± 0.03	0.36^d ± 0.03	0.43^e ± 0.06	0.51^f ± 0.01

Data are expressed as the mean ± standard deviation (n = 5).

Means in the same row followed by the same letter ^(a–f) are not significantly different.

3.6. Sensory evaluation of date bars fortified with various levels of FGLP

It is critical to recognize the expectations of the customer, orient the designed product toward them, and then share and clarify the importance of the produced item to the consumer during the process of design (Okoye, 2015). The sensory properties of date bars supplemented with levels of FGLP are presented in Table 6. Date bars’ appearance grades varied from 8.86 to 9.80. The highest values were obtained with the control sample and date bars enriched with 2.5 and 5.0% FGLP (9.80, 9.89, and 9.89, respectively). The appearance scores of control bars and date bars with 2.5 and 5.0% FGLP did not vary significantly. Additional FGLP resulted in a significant drop in appearance values. However, the samples with the least appearance scores contained 12.5% FGLP. Date bar taste grades ranged from 9.68 to 9.80. There were no significant differences in taste grades among control samples and date bars supplemented with 2.5, 5.0, and 7.5% FGLP, however, taste scores for date bars at higher enhancement quantities were significantly reduced, with the lowest score (9.68) noted for date bars fortified with 12.5% FGLP. Referring to the organoleptic evaluation results, date bars fortified with 0–7.5% FGLP earned the highest flavor scores (9.80–9.88), whereas date bars fortified with 12.5% FGLP received the lowest (8.80). There were no significant (p ≥ 0.05) changes in the exterior color among control date bars and those with 2.5 and 5.0% FGLP. Higher FGLP enhancements (10 and 12.5%) resulted in significant color score reductions. Date bars with 2.5–7.5% FGLP and the control date bars received the highest overall acceptance (9.20–9.30). All date bar samples containing up to 7.5% FGLP showed no statistically significant variations in overall acceptance. On the contrary, date bars supplemented with 12.5% FGLP picked up the lowest overall acceptance score (8.70).

Table 6. Sensory evaluation of date bars fortified with various levels of FGLP.

Parameters	DSB (KDP: FGLP %)
	100:0	97.5:2.5	95:5	92.5:7.5	90:10	87.5:12.5
Appearance	9.80^a ± 0.25	9.89^b ± 0.28	9.89^b ± 0.34	9.88^b ± 0.48	8.87^c ± 0.54	8.86^c ± 0.74
Flavor	9.80^a ± 0.47	9.88^b ± 0.41	9.86^b ± 0.27	9.84^c ± 0.54	9.82^c ± 0.68	8.80^d ± 0.26
Taste	9.80^a ± 0.36	9.86^a ± 0.36	9.81^bc ± 0.63	9.77^c ± 0.64	9.72^c ± 0.74	9.68^c ± 0.54
Color	8.30^a ± 0.45	8.05^b ± 0.91	8.00^b ± 0.92	7.90^c ± 0.28	7.90^c ± 0.57	7.87^d ± 0.37
Overall acceptability	9.30^a ± 0.27	9.30^a ± 0.26	9.20^b ± 0.46	9.20^b ± 0.72	9.00^c ± 0.36	8.70^d ± 0.98

Data are expressed as the mean ± standard deviation.

Means in the same row followed by the same letter ^(a–d) are not significantly different.

4. Conclusion

Lentil seeds possess a high nutritional value; they have important macro- and micronutrient components, and they have compounds that encourage mineral bioavailability. The nutritional qualities of the date bars were significantly enhanced by combining date paste with different quantities of fried green lentil powder (FGLP). The protein content of the enriched DSB samples improved significantly as the FGLP substitution amount increased. The highest quantities of protein were detected in DSB samples enriched with 10.0 and 12.50% FGLP. As the FGLP supplementation quantity progressed, the crude fiber content of DSB samples increased considerably (p ≤ 0.05). Date bars enriched with 12.5% FGLP met the isoleucine, leucine, lysine, total sulfur amino acids, total aromatic amino acids, threonine, and valine requirements by 78.2, 100, 55.1, 70.4, 91.7, 46.1, and 67.7%, respectively. Sensory assessment findings suggested no significant differences in date bar samples supplemented with 2.5–7.5% FGLP.

Abbreviations
FGLP	=	fried green lentil powder
KDP	=	Khudri dates (Phoenix dactylifera L.) paste
GL	=	olive oil
DSB	=	date fruit snack bars
P-PER	=	the predicted protein efficiency ratio
FAMEs	=	fatty acid methyl esters
FID	=	flame ionization detector
IUPAC	=	International Union of Pure and Applied Chemistry
USDA	=	United States Department of Agriculture

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Researcher would like to thank the Deanship of Scientific Research, Qassim University for funding publication of this project.

Notes on contributors

Rehab F. M. Ali

Rehab F. M. Ali is a Professor of Biochemistry at the Faculty of Agriculture, Cairo University. At the same time, she is an associate professor of biochemistry and nutritional biochemistry at the Department of Food Science and Human Nutrition, College of Agriculture and Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia. Her research interest focuses on lipid chemistry, Biochemical Experiments, Antioxidant Activity of Natural Products, Bio-active compounds, functional foods, and coffee products as well as extending the shelf life of food products.