Assessment of physicochemical parameters, and antioxidant properties of mango concentrate during different storage intervals

ABSTRACT

Pakistan is one of the biggest mango producing country in the world. Post-harvest losses of mango occur due to lack of storage facilities. Mango can be converted into concentrate to utilize it for longer period. In the current study, the physicochemical profile and storage stability of mango concentrate was investigated to evidence the opportunity of preservation method. Three different concentrations (0.1%, 0.2%, and 0.5%) of citric acid, sodium benzoate and potassium sorbate were applied. All chemical preservatives significantly (p ˂ 0.05) increased viscosity, total soluble solids (TS), reducing sugar (RS), non-reducing sugar (NRS), total soluble solids (TSS), and titratable acidity (TA), while the moisture content, pH, DPPH antioxidant activity, TPC (total phenolic content), TFC (total flavonoid content) and the level of texture acceptance decreased during the storage. The moisture content was decreased from 43.4% to 34.9% during storage. Phytochemical analysis showed that mango concentrate is a potential source of antioxidant compounds and has higher DPPH radical scavenging activity. Regarding preservation solution, it is suggested that sodium benzoate and citric acid might be utilized for industrial applications.

KEYWORDS:

• Mango concentrate
• physicochemical properties
• preservation
• quality attributes

Introduction

Mango (Mangifera indica L.) is an important fruit which is grown in tropical and subtropical region of Indo-Pak. Botanically, mango is an exotic fruit belongs to Anacardiaceae. It is a family which includes numerous species of tropical fruits tree plants.^[1] Mango has been cultivated from centuries but now it is an important crop of tropical region of South America, Hawaii, Asia, Caribbean, and Africa. These regions are producing mango up to about 43 million tons. Pakistan is 5th biggest mango producing countries in the World and covers 4.3% of the Global mango production.^[2,3]

Mango (Mangifera indica L.) is a tropical fruit that is a good source of nutrients, bioactive compounds (phenolics, ascorbic acid and carotenoids) and other dietary antioxidants.^[4] Phenolic compounds are closely associated with the sensory and nutritional quality of fresh and processed fruits products.^[5] Furthermore, the phenolic compounds are directly contributed to desirable and undesirable aroma and flavors of the food. However, the flavonoids are the biggest class of phenolic substances and are distributed in variable amounts in plant pigments from fruits and beverages^[6]. It is played a vital role in human health by decreasing the risk of cancer, inflammatory and viral diseases. Some pharmaceutical industries are used flavonoids in nutraceutical supplements.^[7] Moreover, flavonoids are also used in food industry to preserve the food and to provide the color and flavor.^[8]

The chemical preservation of mango pulp and concentrates is the most common and widely used in all over the world. It may be due to the cheapest method of preservation among several methods.^[9,10] Presently, sodium benzoate, potassium sorbate, potassium metabisulphate and citric acid are commonly used as chemical preservatives in the products intended for long-term storage because of their better antimicrobial activity.^[11] Most of chemical preservatives in food products are used with the objective to achieve antioxidant properties, increase the acidity of the food, reduce the moisture contents of the foods. These conditions can be slow down the ripening process and prevent the microorganism’s growth.^[12] These preservatives help to keep the food fresher for long periods of time, extending shelf life and slowing or preventing the change in color.

The objective of this study was to investigate the effects of different concentrations of preservatives on mango concentrate properties and storage stability. For the preservation of mango concentrates, the citric acid, sodium benzoate, and potassium sorbate were used to influence storage time. The effects of different concentration were measured by performing physicochemical characteristics, antioxidant activity, and sensorial profile. The research is needed because it provides valuable information about nutritional and economic standpoints.

Materials and methods

Preparation of pulp

The fresh and clean mangos were collected from mango form. After that, mangos were weighed, sorted, graded and thoroughly washed under running water. Cleaned fruits were peeled, sliced by a sharp clean stainless-steel knife. The slices were pulped using an electric blender for preparation of a smooth paste structure. These processes were performed under hygienic lab conditions in order to reduce the risk of contamination.

Preparation of concentrate

TSS of mango pulp was checked to be 18.4°. Then, the sugar was added in order to prepare the mango concentrate. After that, the pulp was subjected to heating. The mango pulp concentrate was prepared by application of heat treatment until 49° degree of concentration is achieved. The material was concentrated in such way to avoid nutrients loss due to high temperature. Furthermore, preservatives of different concentration were added into the concentrate according to treatment plan as described in Table 1. Then, concentrate was filled into the sterilized plastic jars of 200 ml. This concentrate was store at ambient room temperature for 60 days for further analysis.

Table 1. Treatment Plan of Different Types of Preservatives.

Preservatives		Na-Benzoates (%)			Citric Acid (%)			Potassium Sorbate (%)
Days	T1	T2	T3	T4	T5	T6	T7	T8	T9	T10
0	0	0.1	0.2	0.5	0.1	0.2	0.5	0.1	0.2	0.5
15	0	0.1	0.2	0.5	0.1	0.2	0.5	0.1	0.2	0.5
30	0	0.1	0.2	0.5	0.1	0.2	0.5	0.1	0.2	0.5
45	0	0.1	0.2	0.5	0.1	0.2	0.5	0.1	0.2	0.5
60	0	0.1	0.2	0.5	0.1	0.2	0.5	0.1	0.2	0.5

Physicochemical analysis

Total Soluble Solid (TSS) was determined of each sample using a digital refractometer (ATAGO, Japan) at 29 ± 1°C. Temperature was applied accordingly to the described method of AOAC^[13] method no. 932.12. The pH values were recorded by using a pH-meter (Inolab. WTW Series, Germany), as illustrated in the AOAC^[13] method no. 981.12. Titratable acidity of mango pulp was determined as described by the AOAC^[14] method No 942.15. Total and reducing sugars were calculated by using Fehling’s solution as reported in the AOAC^[14] method No. 925.35.

Moisture content was analyzed by oven drying method at 105°C till constant weight is achieved as described in the AOAC^[14] method No. 925.45. The viscosity was measured by using a Brookfield Viscometer according to method of Enriquez‐Fernandez et al.^[15]

Sensory analysis

Sensory evaluation of the mango concentrate was carried out by a panel who were proficient in the sensory evaluation. All the participants recruited for the test were well familiar with the taste of mango and scored the samples for their sensory attributes using a 9-point hedonic scale.^[16]

Phytochemicals analysis

Total Phenolic Content (TPC)

The diluted extracts (1 ml) were oxidized with 2.5 ml of Folin – Ciocalteau’s reagent (10%) followed by neutralization with 2 ml sodium carbonate (7.5%). The mixture was kept in dark for 45 minutes, and the absorbance was measured at 765 nm wavelength using a spectrophotometer (UV-9200, UK). Gallic acid was used as a standard.^[17]

Total flavonoid contents

The diluted sample extracts (1 ml) were mixed with 0.3 ml of sodium nitrite (5%). After 5 minutes, 0.6 ml of aluminum chloride (10%) was added and mixed. It was followed by the addition of 2 ml of 1 M sodium hydroxide after 5 minutes. Finally, the absorbance was measured at 510 nm wavelength using a spectrophotometer (UV-9200, UK). The total flavonoid was calculated using quercetin as a standard.^[18]

Free radical (DPPH) scavenging activity

The stable radical 1,1-diphenyl 1–2-picrylhydrazyl (DPPH) was used for the determination of free radical scavenger activity of the mango concentrate.^[19] Different concentrations of each sample were added at an equal volume, to methanol solution of DPPH (0.2 Mm). The absorbance was recorded at 517 nm after 30 min at room temperature. The percent of scavenging activity was calculated as the ratio of the absorption of the sample against the control.

$\mathrm{R}\mathrm{a}\mathrm{d}\mathrm{i}\mathrm{c}\mathrm{a}\mathrm{l}\mathrm{s}\mathrm{c}\mathrm{a}\mathrm{v}\mathrm{e}\mathrm{n}\mathrm{g}\mathrm{i}\mathrm{n}\mathrm{g}\mathrm{a}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{v}\mathrm{i}\mathrm{t}\mathrm{y}\left(\mathrm{\%}\right)=\frac{\mathrm{A}\left(\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{l}\right)-\mathrm{A}\left(\mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}\right)\hspace{0.17em}\times 100}{\mathrm{A}\left(\mathrm{c}\mathrm{o}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{o}\mathrm{l}\right)}$

Statistical analysis

The results were analyzed using standard statistical tools and procedures.^[20] All experiments were conducted at least in duplicate and the data expressed as mean ± standard deviation. Statistical analyses were carried out using Statistix 8.1. The one-way analysis of variance (ANOVA) was applied to evaluate significant differences among samples at a 95% confidence interval. Principal Component Analysis (PCA) was performed to predict the total variability between days of storage and physicochemical characteristics (viscosity, moisture, pH, titratable acidity), total sugars, total soluble solids, total flavonoids and sensorial properties (texture).

Results and discussion

Viscosity

The effect of preservatives and storage stability on mango concentrate viscosity is shown in Table 2. The storage and treatments influenced the viscosity to a significant value (p < .05). The interactive effect of storage interval and treatment was also found significant (p < .05). The viscosity was found to increase from 44.1 cP to 49.9 cP during 60 days of storage. The mean viscosity for treatments ranged between 44.8 cP to 48.2 cP. The highest viscosity of mango concentrate was observed in T₁ (control). The lowest viscosity of mango concentrate was noted in T₇ (Potassium sorbate 0.5%), during 60 days of storage. The viscosity depends upon inter-molecular forces between molecules and water solute, the strength of hydrogen bonds and intermolecular forces depending on the concentration and temperature.^[21] An increase in total soluble solids tends to lead to an increase in hydrated molecules and hydrogen bonding with hydroxyl group of the solute^[22]). Because of this, the behavior of the concentrate stream increased, and the viscosity increased. The increase in viscosity could be explained also by the pectin, water, and sugar network and the entanglement of glucose chains.^[23]

Table 2. Effect of preservation methods on viscosity (cP) and total sugars (%) of mango concentrate during storage.

	Viscosity						Total Sugars
	0 day	15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	43.7 ± 0.5x	46.4 ± 0.1mno	48.5 ± 0.4hi	50.3 ± 0.3cde	52.1 ± 0.6a	48.2A	49.6 ± 0.20pq	51.9 ± 0.30ij	54.6 ± 0.21cd	55.5 ± 0.20b	57.0 ± 0.26a	53.7A
T2	43.9 ± 0.9vwx	45.7 ± 0.2op	47.3 ± 0.2kl	49.6 ± 0.5ef	50.9 ± 0.6bc	47.5B	49.4 ± 0.10pq	50.9 ± 0.46lm	53.2 ± 0.49efg	54.6 ± 0.30cd	55.8 ± 0.10b	52.8B
T3	44.5 ± 0.4rstuv	45.4 ± 0.2pq	47.1 ± 0.7klm	49.1 ± 0.7fgh	50.6 ± 0.6c	47.4B	49.3 ± 0.10pq	50.7 ± 0.42lm	53.6 ± 0.25e	54.4 ± 0.26d	55.4 ± 0.15b	52.7C
T4	44.1 ± 0.8uvwx	45.2 ± 0.1pqr	47.0 ± 0.3klmn	48.8 ± 0.4ghi	49.8 ± 0.5def	47.0B	49.4 ± 0.26pq	50.4 ± 0.20mn	52.5 ± 0.15hi	54.5 ± 0.21d	55.2 ± 0.10bc	52.4E
T5	43.9 ± 0.5vwx	45.2 ± 0.5pqrs	46.7 ± 0.4lmn	47.5 ± 0.4k	48.8 ± 0.3ghi	46.4C	49.4 ± 0.15pq	50.6 ± 0.15lm	52.6 ± 0.21fgh	53.6 ± 0.32e	54.5 ± 0.32d	52.1F
T6	44.4 ± 0.7tuvw	45.2 ± 0.6pqrs	46.6 ± 0.2lmn	46.3 ± 0.8no	48.2 ± 0.4ij	46.2C	49.3 ± 0.21pq	50.3 ± 0.15mno	51.6 ± 0.21jk	52.6 ± 0.25gh	53.3 ± 0.21e	51.4 G
T7	44.1 ± 0.4uvwx	44.5 ± 0.2rstuv	44.8 ± 0.2qrstu	44.9 ± 0.2pqrs	45.5 ± 0.4pq	44.8D	49.3 ± 0.26pq	49.4 ± 0.21nop	50.6 ± 0.25lm	51.3 ± 0.17j	52.1 ± 0.59kl	50.5 H
T8	43.7 ± 0.6wx	45.3 ± 0.4pq	47.5 ± 0.3jk	49.4 ± 0.2fq	51.6 ± 0.2ab	47.6B	49.3 ± 0.21op	50.7 ± 0.15 lm	53.4 ± 0.55e	54.3 ± 0.15d	55.8 ± 0.15b	52.7C
T9	44.2 ± 0.5tuvwx	45.2 ± 0.2pqrs	47.3 ± 0.7kl	48.6 ± 0.4hi	50.9 ± 0.7bc	47.3B	49.1 ± 0.15q	50.6 ± 0.31lm	53.4 ± 0.25e	54.6 ± 0.25d	55.7 ± 0.17b	52.7C
T10	44.3 ± 0.4tuvwx	45.0 ± 0.6pqrst	46.8 ± 0.4klmn	48.5 ± 0.5hi	50.4 ± 0.3cd	47.0B	49.3 ± 0.25pq	50.4 ± 0.25mno	53.2 ± 0.45ef	54.5 ± 0.49d	55.5 ± 0.15b	52.6D
Mean	44.1 E	45.3 D	47.0 C	48.3 B	49.9 A		49.3 E	50.6 D	52.9 C	54.0 B	55.0 A

T₁ Control, T₂ Sodium Benzoate 0.1% T₃ Sodium Benzoate 0.2% = T₄ Sodium Benzoate 0.5% = T₅ Potassium Sorbate 0.1%, T₆ Potassium Sorbate 0.2%, T₇ Potassium Sorbate 0.5%, T₈ Citric Acid 0.1%, T₉ Citric Acid 0.2%, T₁₀ Citric Acid 0.5%. a-x – means followed by different lowercase letters in the same column indicate significant differences (p < .05) between storage days, A-H – different uppercase letters in the same column indicate significant differences (p < .05) between the mean of the samples and in the same row indicate significant differences (p < .05) between the mean of the storage days values.

Total sugars

The result regarding the total sugars is given in Table 2. The analyzed samples of mango concentrate showed that the total sugar was significantly affected by different preservatives. The storage and treatments influenced the total sugars to a significant value (p < .05). The total sugar content was recorded to be increase x during storage. The average total sugars varied from 50.1% to 57.3% during storage. The minimum average total sugar was observed in T₇. The maximum average of total sugar was recorded in T₁ (control). The results are closely related to the findings of Yadav et al.,^[24] who revealed that potassium sorbate give least value of total sugars during storage and preservative resist to increase in mean value of total sugar after up to 90 day of storage. The increase of total sugars in T₁ might be due to the conversion of polysaccharides into monosaccharides.^[25]

Reducing sugar

The data pertaining to reducing sugars in mango concentrate is presented in Table 3. The main effects for storage indicate that the minimum reducing sugars was observed at the beginning of the experiment and increased significantly (p < .05) during 60 days of storage. The reducing sugar was recorded to be high during storage periods of time. The average reducing sugars varied from 27.1% to 29.3% during storage. On different treatments, the minimum average reducing sugar was observed in T₇ (P.S 0.5%) which was 27.1. The maximum average reducing sugars was recorded in T₁ (control). The maximum increase in reducing sugars was observed in T₁ (from 26.7% to 31.7%), while the minimum increase in total sugars was recorded in T₇ (from 26.1% to 27.8%). Overall, it can be seen from the data that the increase in reducing sugar is due to the inversion of sucrose into simple sugar during storage. The present results are in agreement with the findings of Babsky et al.^[26]

Table 3. Effect of preservation methods on Reducing sugars (%) and Non-Reducing sugars (%) of mango concentrate during storage.

	Reducing Sugars							Non-reducing Sugars
	0 day		15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	26.7 ± 0.20q		28.0 ± 0.17c	29.4 ± 0.12ef	30.5 ± 0.35b	31.7 ± 0.15a	29.3A	22.6 ± 0.23tu	23.9 ± 0.17lmn	25.2 ± 0.10ef	26.5 ± 0.67b	27.1 ± 0.35a	25.1A
T2	26.5 ± 0.54qrs		27.3 ± 0.35no	28.7 ± 0.23hij	29.4 ± 0.15ef	30.1 ± 0.06bc	28.4B	22.9 ± 0.63rst	23.3 ± 0.32pqr	24.7 ± 0.15gh	25.4 ± 0.25cdef	25.7 ± 0.06c	24.4B
T3	26.3 ± 0.30rs		27.5 ± 0.26mno	28.6 ± 0.15hij	29.3 ± 0.15f	29.9 ± 0.06cd	28.3C	22.8 ± 0.40t	23.5 ± 0.23opq	24.5 ± 0.15hijk	25.3 ± 0.26def	25.5 ± 0.10cdef	24.3C
T4	26.3 ± 0.21rs		27.2 ± 0.10op	28.3 ± 0.10jk	29.4 ± 0.12ef	29.8 ± 0.06cde	28.2D	22.2 ± 0.38u	23.2 ± 0.10qrs	24.1 ± 0.06klm	25.1 ± 0.06fg	25.4 ± 0.06cdef	24.0D
T5	26.8 ± 0.60pq		27.3 ± 0.10no	28.5 ± 0.35hij	28.9 ± 0.20gh	29.4 ± 0.15ef	28.2D	22.6 ± 0.64u	23.3 ± 0.06pqr	24.2 ± 0.06ijkl	24.7 ± 0.15hi	25.1 ± 0.17fg	24.0D
T6	26.6 ± 0.55qr		27.1 ± 0.06op	27.7 ± 0.25lmn	28.4 ± 0.15ijk	28.7 ± 0.10hij	27.7E	22.7 ± 0.37t	23.2 ± 0.10qrs	23.8 ± 0.10mno	24.2 ± 0.10jkl	24.6 ± 0.12hi	23.7E
T7	26.1 ± 0.40s		26.6 ± 0.12qr	27.3 ± 0.10no	27.7 ± 0.12lmn	27.8 ± 0.32lm	27.1F	22.7 ± 0.21t	22.8 ± 0.10st	23.3 ± 0.15pqr	23.6 ± 0.06nop	24.2 ± 0.06klm	23.3F
T8	26.2 ± 0.54rs		27.3 ± 0.15no	28.8 ± 0.30h	29.4 ± 0.10ef	30.0 ± 0.12c	28.3C	22.7 ± 0.06t	23.3 ± 0.25pqr	24.5 ± 0.25hijk	25.7 ± 0.15cd	25.5 ± 0.00cdef	24.3C
T9	26.5 ± 0.60qrs		27.3 ± 0.21no	28.8 ± 0.15hi	29.4 ± 0.10ef	29.9 ± 0.15c	28.4B	22.6 ± 0.45tu	23.4 ± 0.21opq	24.6 ± 0.10hij	25.2 ± 0.10ef	25.6 ± 0.15cde	24.3C
T10	26.4 ± 0.40qrs		27.6 ± 0.31lmn	28.7 ± 0.20hij	29.2 ± 0.15fg	29.5 ± 0.17c	28.3C	22.6 ± 0.50tu	23.6 ± 0.30nop	24.5 ± 0.25hijk	25.1 ± 0.25fg	25.7 ± 0.06c	24.3C
Mean		26.4 E	27.3 D	28.5 C	29.2 B	29.7 A		22.6 E	23.4 D	24.4 C	25.1 B	25.4 A

T₁ Control, T₂ Sodium Benzoate 0.1% T₃ Sodium Benzoate 0.2% = T₄ Sodium Benzoate 0.5% = T₅ Potassium Sorbate 0.1%, T₆ Potassium Sorbate 0.2%, T₇ Potassium Sorbate 0.5%, T₈ Citric Acid 0.1%, T₉ Citric Acid 0.2%, T₁₀ Citric Acid 0.5%. a-s – means followed by different lowercase letters in the same column indicate significant differences (p < .05) between storage days, A-E – different uppercase letters in the same column indicate significant differences (p < .05) between the mean of the samples and in the same row indicate significant differences (p < .05) between the mean of the storage days values.

Non-reducing sugar

The result regarding the non-reducing sugar is given in Table 3. The analyzed samples of mango concentrate showed that non-reducing sugar was significantly affected by different preservatives. The storage and treatments influenced the non-reducing sugar to a significant value (p < .05). The increasing trend was recorded in non-reducing sugars during storage. The average non-reducing sugars varied from 22.6% to 25.4% at different storage. The minimum average non-reducing sugar was observed in T₇ (P.S 0.5%), while the maximum average non-reducing sugar was recorded for T₁ (control). The main effects for storage indicate that the minimum non-reducing sugars were observed at the beginning of the experiment, then it increased significantly (p < .05) during storage until the maximum non-reducing sugars value reached in 60^th days of storage. The increase in non-reducing sugar is due to the inversion of polysaccharides into oligosaccharides and disaccharides. These results are supported by the findings of Rehman et al.^[27]

Total soluble solids

The results regarding the total soluble solids are shown in Table 4. The minimum total soluble solids were observed on the beginning of the experiment and increased significantly (p < .05) during storage. The average total soluble solids varied from 49.3 to 55.0 from the beginning to the end of the study. The highest value was observed in T₁. The minimum value was noted in T₇ (P.S 0.5%). The increase in TSS is due to the hydrolytic changes in starch and conversion of starch into mono and disaccharides. The T7 (P.S 0.7%) showed resistance to conversion of polysaccharides or disaccharides into simple sugars. These results are in agreement with the findings of Rathore et al^[28] who observed an increase in total soluble solids in mango with storage.

Table 4. Effect of preservation methods on TSS and Moisture contents (%) of mango concentrate during storage.

	Total Soluble Solids							Moisture contents
	0 day		15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	49.9 ± 0.15wx		51.7 ± 0.10mno	53.3 ± 0.21g	54.5 ± 0.15bc	55.7 ± 0.15a	53.1A	43.4 ± 1.01abc	41.9 ± 1.14efgh	39.8 ± 0.71mn	36.8 ± 0.71qrstu	34.9 ± 0.57v	39.4F
T2	49.7 ± 0.06xy		50.9 ± 0.45rs	52.3 ± 0.06jk	53.5 ± 0.21efg	54.5 ± 0.21bc	52.2 B	43.1 ± 0.61abcd	42.7 ± 0.40bcdef	39.6 ± 0.61mn	36.9 ± 0.46pqr	35.4 ± 0.82v	39.5E
T3	49.7 ± 0.10xy		50.5 ± 0.20tu	52.6 ± 0.15hij	53.4 ± 0.15efg	54.4 ± 0.15c	52.2 B	42.4 ± 0.50cdefg	40.6 ± 0.50ijklm	39.1 ± 0.81no	37.2 ± 0.67pqrst	35.1 ± 0.44v	38.9 H
T4	48.9 ± 0.20a		50.4 ± 0.20tuv	51.6 ± 0.10no	52.4 ± 0.21ij	53.4 ± 0.12fg	51.4 E	42.4 ± 1.11cdefg	41.7 ± 0.96fghi	39.3 ± 0.76no	37.1 ± 0.59pqr	35.8 ± 0.26tuv	39.3 G
T5	49.8 ± 0.12x		50.4 ± 0.15tuv	51.2 ± 0.15pqr	52.3 ± 0.12jk	53.4 ± 0.25fg	51.5 D	43.4 ± 0.95abc	42.0 ± 0.26defgh	39.8 ± 0.59mn	37.4 ± 0.55pqrst	35.9 ± 0.32stuv	39.7D
T6	49.7 ± 0.10xy		50.1 ± 0.35vw	50.9 ± 0.31qrs	52.1 ± 0.17kl	53.2 ± 0.21g	51.2 F	43.1 ± 0.76abcde	41.9 ± 0.59efgh	40.0 ± 1.47jklmn	38.3 ± 0.55op	37.2 ± 0.59pqrs	40.1C
T7	49.4 ± 0.45yz		49.8 ± 0.31x	50.5 ± 0.32tu	51.2 ± 0.21pq	52.0 ± 0.10lm	50.6 G	42.0 ± 0.50defgh	41.9 ± 0.67efgh	41.1 ± 0.60hijk	39.9 ± 1.93lmn	39.9 ± 0.20klm	41.0A
T8	49.6 ± 0.15xyz		51.4 ± 0.20op	52.6 ± 0.15hij	53.7 ± 0.15e	54.8 ± 0.10b	52.5 B	43.8 ± 0.46ab	41.3 ± 1.21ghij	39.4 ± 0.55mno	37.3 ± 0.55pqr	35.8 ± 0.57uv	39.5E
T9	49.6 ± 0.12xyz		50.7 ± 0.20st	52.7 ± 0.10hi	53.7 ± 0.20ef	54.5 ± 0.10bc	52.2 B	43.2 ± 1.52abcd	41.2 ± 1.22ghijk	39.3 ± 0.68no	37.4 ± 0.52pqr	36.2 ± 0.95rstuv	39.5E
T10	49.3 ± 0.25z		50.3 ± 0.12uv	51.8 ± 0.10lmn	52.9 ± 0.15h	54.1 ± 0.20d	51.7C	44.3 ± 0.58a	43.0 ± 0.59abcde	40.0 ± 0.47klmn	37.8 ± 0.75pq	35.9 ± 0.62stuv	40.2B
Mean		49.6 E	50.6 D	52.0 C	53.0 B	54.0 A		43.1 A	41.8 B	39.7 C	37.6 D	36.2 E

T₁ Control, T₂ Sodium Benzoate 0.1% T₃ Sodium Benzoate 0.2% = T₄ Sodium Benzoate 0.5% = T₅ Potassium Sorbate 0.1%, T₆ Potassium Sorbate 0.2%, T₇ Potassium Sorbate 0.5%, T₈ Citric Acid 0.1%, T₉ Citric Acid 0.2%, T₁₀ Citric Acid 0.5%. a-z – means followed by different lowercase letters in the same column indicate significant differences (p < .05) between storage days, A-H – different uppercase letters in the same column indicate significant differences (p < .05) between the mean of the samples and in the same row indicate significant differences (p < .05) between the mean of the storage days values.

Moisture contents

The results regarding moisture contents of mango concentrate are shown in Table 4. The results indicated that the maximum moisture contents were observed at the beginning of the experiment and decreased significantly (p < .05) during storage. The average moisture contents varied from 43.1% to 36.2%. The maximum decrease in moisture contents was observed in T₁ (control). The minimum decrease in moisture contents was recorded for T₇ (P.S 0.5%). The loss of moisture contents is due to the high ambient room temperature and increase in others parameters. These results are closely related with the findings of Ayala-Zavala et al.^[29]

pH

The pH is one important parameter for microbial and enzymatic action. Thus, it is related to shelf life of the fruit products. The data obtained for the pH of mango concentrates are shown in Table 5. The effects of storage indicate that the maximum pH was observed at the beginning of the experiment and decreased significantly (p < .05) during storage. The average pH varied from 5.17 to 4.81. The highest decrease in pH values was observed in T₁, while the lowest decrease in pH values was observed in T₇ during 60 days of storage. The lowest pH was observed in citric acids that may be due to the acidic nature of preservative. The decreasing trend in average pH was recorded due to concentrations of citric acid. The finding of study regarding the pH was in agreement with the studies of Akhtar et al.^[30] and Makroo et al.^[23] who observed significant change in pH during storage after application of chemical preservatives in mango pulp. Some fruits have already acidic pH that help the fruits to be degraded from microorganisms. The water activity can be increased by addition of acids released some water present in the matrix of the fruit material. The fruit concentrates act as pectin, water, and sugar gels, where water and pectin play an important role in the networking for the stability of the gel.^[31] The gel networks are generally made by the ordered conformation and associations between the pectin-sugar. However, it causes the water to get trapped, and this networking is highly sensitive to the pH change caused by the addition of acid.^[32]

Table 5. Effect of preservation methods on pH and Titratable acidity (%) of mango concentrate during storage.

	pH						Titratable Acidity
	0 day	15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	5.50 ± 0.01a	5.42 ± 0.01b	5.16 ± 0.01p	4.93 ± 0.03u	4.73 ± 0.01wx	5.15 B	0.54 ± 0.01uv	0.57 ± 0.01qr	0.62 ± 0.01ik	0.68 ± 0.01g	0.79 ± 0.01a	0.64 D
T2	5.40 ± 0.01bc	5.34 ± 0.01ef	5.20 ± 0.01no	5.05 ± 0.01s	4.99 ± 0.01t	5.20 A	0.54 ± 0.03uv	0.57 ± 0.01qr	0.60 ± 0.01no	0.63 ± 0.01jk	0.68 ± 0.01q	0.60 E
T3	5.40 ± 0.01b	5.36 ± 0.01de	5.25 ± 0.01jkl	5.17 ± 0.01p	5.04 ± 0.01s	5.24 A	0.54 ± 0.01uv	0.56 ± 0.01rs	0.59 ± 0.00q	0.62 ± 0.01klm	0.66 ± 0.01hi	0.59 F
T4	5.39 ± 0.01bc	5.37 ± 0.01cd	5.23 ± 0.01lm	5.10 ± 0.01r	4.98 ± 0.01t	5.22 A	0.54 ± 0.01uv	0.55 ± 0.01st	0.58 ± 0.01pq	0.61 ± 0.01mn	0.66 ± 0.01j	0.59 F
T5	5.33 ± 0.02fg	5.27 ± 0.01ijk	5.21 ± 0.01mn	5.13 ± 0.02qr	5.02 ± 0.02s	5.19 B	0.53 ± 0.01tu	0.54 ± 0.01rs	0.57 ± 0.01op	0.61 ± 0.01lm	0.63 ± 0.01jk	0.58 G
T6	5.31 ± 0.01gh	5.28 ± 0.01ij	5.25 ± 0.01kl	5.18 ± 0.01op	5.13 ± 0.01q	5.23 A	0.55 ± 0.02tu	0.56 ± 0.01rs	0.59 ± 0.01op	0.61 ± 0.00lm	0.62 ± 0.0 jk	0.59 F
T7	5.31 ± 0.01gh	5.30 ± 0.01hi	5.29 ± 0.01hi	5.29 ± 0.02hi	5.24 ± 0.02lm	5.29 A	0.57 ± 0.01tu	0.58 ± 0.01rs	0.58 ± 0.01op	0.59 ± 0.01lm	0.59 ± 0.01jk	0.58 G
T8	4.87 ± 0.01v	4.70 ± 0.09yz	4.62 ± 0.01xy	4.55 ± 0.03xy	4.44 ± 0.03x	4.64 C	0.63 ± 0.01qr	0.67 ± 0.01pq	0.69 ± 0.01pq	0.72 ± 0.01kl	0.76 ± 0.01q	0.69 C
T9	4.76 ± 0.02wx	4.71 ± 0.02xy	4.67 ± 0.02xy	4.54 ± 0.02y	4.43 ± 0.02y	4.62 C	0.67 ± 0.01gh	0.70 ± 0.01f	0.72 ± 0.01e	0.73 ± 0.01d	0.76 ± 0.01bc	0.72 B
T10	4.43 ± 0.02xy	4.40 ± 0.01wx	4.38 ± 0.01x	4.23 ± 0.02x	4.12 ± 0.02z	4.31 D	0.71 ± 0.02e	0.73 ± 0.01d	0.75 ± 0.01c	0.77 ± 0.01b	0.79 ± 0.00a	0.75 A
Mean	5.17 A	5.11 B	5.03 C	4.92 D	4.81 E		0.58 E	0.60 D	0.63 C	0.66 B	0.69 A

T₁ Control, T₂ Sodium Benzoate 0.1% T₃ Sodium Benzoate 0.2% = T₄ Sodium Benzoate 0.5% = T₅ Potassium Sorbate 0.1%, T₆ Potassium Sorbate 0.2%, T₇ Potassium Sorbate 0.5%, T₈ Citric Acid 0.1%, T₉ Citric Acid 0.2%, T₁₀ Citric Acid 0.5%. a-z – means followed by different lowercase letters in the same column indicate significant differences (p < .05) between storage days, A-G – different uppercase letters in the same column indicate significant differences (p < .05) between the mean of the samples and in the same row indicate significant differences (p < .05) between the mean of the storage days values.

Titratable acidity

The results related to titratable acidity are listed in Table 5. The storage effects indicated that the minimum titratable acidity was observed at the beginning of the experiment and increased significantly (p < .05) during storage. The average titratable acidity varied from 0.58% to 0.69%. The highest increase in titratable acidity was observed in T₁, while the minimum increase in titratable acidity was noted in T₇. The increasing effect is caused by the microbial growth. This change was influenced by the conversion of sodium benzoate into benzoic acid and potassium sorbate into sorbic acid. The significant changes were noted at storage intervals due to increased concentration of preservatives. Citric acid presented a considerable acidity at the beginning of the experiment in mango concentrates because of its acidic nature. Preservatives show increasing trend in titratable acidity along with storage period of time.^[33]

DPPH radical scavenging activity

The data regarding the radical scavenging activity is shown in Table 6. The effects of storage indicate that the maximum DPPH was recorded at the beginning of the experiment and decreased significantly (p < .05) during storage. The average DPPH varied from 46.6% to 54.2%. The maximum decrease in radical scavenging activity was observed in T₁, while the minimum decrease in radical scavenging activity of mango concentrate was noted in T_7. A previous study describes that the radical scavenging activity decreases with the increase in storage time. These findings are agreed with the results of Ibrahim,^[34] who observed a decreasing trend of the antioxidant activity with storage in orange juice.

Table 6. Effect of preservation methods on DPPH radical Scavenging activity (%) and Total phenolic Contents (mg/100 g of GAE eql) of mango concentrate during storage.

	DPPH radical Scavenging activity						Total phenolic Contents
	0 day	15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	52.0 ± 1.00ghi	51.3 ± 0.58hijk	49.7 ± 0.58lm	46.6 ± 0.45rs	44.3 ± 0.58u	48.8 H	66.8 ± 0.60ab	64.5 ± 0.50efg	60.7 ± 0.58k	57.7 ± 0.58opq	53.7 ± 0.58v	60.0F
T2	53.3 ± 0.58def	52.7 ± 1.15efg	50.3 ± 0.58kl	48.7 ± 0.58mno	45.3 ± 0.58tu	50.1 G	65.5 ± 0.87bcde	64.7 ± 0.58efg	62.3 ± 0.58j	58.3 ± 0.58nop	55.7 ± 0.58st	61.3E
T3	55.0 ± 1.00ab	54.7 ± 0.58abc	50.7 ± 0.58jkl	49.0 ± 0.00mn	47.3 ± 0.58pqr	51.3C	66.3 ± 1.13bcd	65.4 ± 0.51cde	63.7 ± 0.58ghi	59.0 ± 1.00mn	56.3 ± 0.58rst	62.1C
T4	55.0 ± 1.00ab	54.0 ± 1.00bcd	51.0 ± 1.00ijk	49.7 ± 0.58lm	47.7 ± 0.58opq	51.5B	65.9 ± 0.57bcd	65.0 ± 0.00def	63.3 ± 0.58hij	59.3 ± 0.58lmn	56.7 ± 0.58qr	62.0D
T5	53.3 ± 0.58def	52.3 ± 0.58fgh	50.3 ± 0.58kl	48.3 ± 0.58nop	47.3 ± 0.58pqr	50.3F	66.7 ± 1.40ab	65.2 ± 1.06cde	63.3 ± 0.58hij	59.7 ± 0.58klm	55.3 ± 0.58tu	62.1C
T6	54.0 ± 1.00bcd	53.3 ± 0.58def	50.3 ± 0.58kl	49.0 ± 0.00mn	47.7 ± 0.58opq	50.9D	66.5 ± 1.20ab	65.3 ± 0.58cde	63.7 ± 0.58ghi	60.3 ± 0.58kl	57.3 ± 0.58pq	62.6B
T7	54.7 ± 0.58abc	54.3 ± 0.58abcd	52.7 ± 0.58efg	51.7 ± 0.58ghij	49.7 ± 0.58lm	52.6A	66.8 ± 0.58a	65.7 ± 0.61bcde	64.7 ± 0.58efg	62.7 ± 0.58ij	60.3 ± 0.58kl	64.0A
T8	54.7 ± 0.58abc	53.3 ± 0.58def	50.3 ± 0.58kl	47.1 ± 0.12qr	45.3 ± 0.58tu	50.1 G	66.4 ± 1.37abc	63.7 ± 0.58ghi	62.3 ± 0.58j	57.7 ± 0.58opq	54.3 ± 0.58uv	60.9F
T9	55.3 ± 0.58a	53.7 ± 0.58cde	50.3 ± 0.58kl	47.3 ± 0.58pqr	45.7 ± 0.58st	50.5E	65.4 ± 0.78bcde	64.1 ± 0.17fgh	62.7 ± 0.58ij	58.3 ± 0.58nop	55.7 ± 0.58st	61.2E
T10	55.0 ± 1.00ab	54.0 ± 0.00bcd	51.7 ± 0.58ghi	47.7 ± 0.58opq	46.0 ± 0.00st	50.9D	66.0 ± 1.81bcd	63.7 ± 0.58ghi	62.3 ± 0.58j	58.7 ± 0.58mn	56.3 ± 0.58rst	61.4E
Mean	54.2 A	53.4 B	50.7 C	48.5 D	46.6 E		66.2 A	64.7 B	62.9 C	59.2 D	56.2 E

T₁ Control, T₂ Sodium Benzoate 0.1% T₃ Sodium Benzoate 0.2% = T₄ Sodium Benzoate 0.5% = T₅ Potassium Sorbate 0.1%, T₆ Potassium Sorbate 0.2%, T₇ Potassium Sorbate 0.5%, T₈ Citric Acid 0.1%, T₉ Citric Acid 0.2%, T₁₀ Citric Acid 0.5%. a-v – means followed by different lowercase letters in the same column indicate significant differences (p < .05) between storage days, A-F – different uppercase letters in the same column indicate significant differences (p < .05) between the mean of the samples and in the same row indicate significant differences (p < .05) between the mean of the storage days values.

Total phenolic contents

The results related to the total phenolic content of mango are shown in Table 6. The effects of storage indicate that the maximum total phenolic contents were observed at the beginning of the experiment and decreased significantly (p < .05) during storage. The average total phenolic contents varied from 66.2 mg to 56.2 mg. The highest decrease in TPC of mango concentrate was noted in T₁, while the lowest decrease was observed in T₇. However, the samples which were not treated with preservatives showed minimum loss as compared to T₁ (control). These results are agreement with the findings of Biglari et al.^[35] and Ong et al.^[36]

Total flavonoids contents

The results related to total flavonoids of mango concentrate are shown in Table 7. The effects of storage indicate that the maximum total flavonoid contents were observed at the beginning of the experiment and decreased significantly (p < .05) during storage. The average total flavonoids contents varied from 7.6 mg to 15.6. The highest decrease in TFC values of mango concentrate was noted in T₁, and the minimum decrease was noted in T₇. The decreasing trend in total flavonoid contents in T₁ (control) was due to the high temperature. Chukwumah et al.^[37] also observed the loss of total flavonoid contents in fruits during storage.

Table 7. Effect of preservation methods on Total Flavonoid Contents (mg/100 g of QUR eql) and texture of mango concentrate during storage.

	Total Flavonoids Contents						Sensory Evaluations (Texture)
	0 day	15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	15.7 ± 0.32a	12.9 ± 0.38fg	9.9 ± 0.51klmn	7.62 ± 0.61o	5.79 ± 0.69p	10.4 H	8.33 ± 0.58a	6.48 ± 0.84ef	5.33 ± 0.58gh	3.67 ± 0.58jk	1.99 ± 0.01l	5.16E
T2	15.8 ± 0.40a	13.6 ± 0.47defg	10.4 ± 0.51jklm	9.47 ± 0.47n	7.47 ± 0.51o	11.4 B	8.33 ± 0.58a	6.85 ± 0.79de	6.74 ± 0.51de	4.67 ± 0.58hi	3.48 ± 0.50k	6.01D
T3	15.1 ± 0.57ab	13.8 ± 0.67cdef	11.3 ± 0.58hij	9.43 ± 0.59n	7.36 ± 0.59o	11.4 B	8.33 ± 0.58a	7.00 ± 0.87cde	6.67 ± 0.58de	5.67 ± 0.58fg	4.33 ± 0.58ijk	6.40C
T4	15.7 ± 0.38a	13.9 ± 0.38cd	11.7 ± 0.46h	10.1 ± 0.17klmn	7.79 ± 0.62o	11.8 B	8.33 ± 0.58a	6.89 ± 0.77de	6.67 ± 0.58de	5.71 ± 0.28fg	4.04 ± 0.61ijk	6.33C
T5	15.6 ± 0.21ab	13.0 ± 0.40efg	10.5 ± 0.50jklm	9.57 ± 0.51mn	7.30 ± 0.27o	11.2 B	8.25 ± 0.44ab	7.44 ± 0.12bcd	6.96 ± 0.06cde	6.33 ± 0.58ef	4.78 ± 0.38hi	6.75C
T6	15.9 ± 0.74a	13.9 ± 0.72cde	10.7 ± 0.46ijk	9.67 ± 0.58lmn	7.72 ± 0.63o	11.6 B	8.19 ± 0.32ab	7.77 ± 0.29abc	7.13 ± 0.28cde	6.67 ± 0.58de	5.33 ± 0.58gh	7.02B
T7	16.0 ± 0.59a	14.7 ± 0.53bc	12.8 ± 0.40g	11.5 ± 0.62hi	9.81 ± 0.70o	12.9 A	8.35 ± 0.60a	8.33 ± 0.58a	8.33 ± 0.58a	8.33 ± 0.57a	8.15 ± 0.26ab	8.30A
T8	15.5 ± 0.40ab	13.2 ± 0.25defg	9.82 ± 0.31jklm	9.47 ± 0.72klmn	7.59 ± 0.49o	11.1 B	8.48 ± 0.50a	7.40 ± 0.35bcd	6.33 ± 0.58ef	4.33 ± 0.58ijk	3.48 ± 0.50k	6.00D
T9	15.6 ± 1.21ab	13.6 ± 0.47cdef	10.5 ± 0.81ijk	9.80 ± 0.72ijkl	8.01 ± 0.89o	11.5 B	8.59 ± 0.52a	6.63 ± 0.55de	6.33 ± 0.58ef	5.33 ± 0.58gh	4.51 ± 0.50hij	6.28C
T10	15.1 ± 0.42ab	13.8 ± 0.76cde	10.7 ± 0.58ijk	10.6 ± 1.04jklm	7.36 ± 0.59o	11.5 B	8.48 ± 0.50a	6.33 ± 0.58ef	6.67 ± 0.58de	5.67 ± 0.58fg	4.33 ± 0.58ijk	6.30C
Mean	15.6 A	13.6 B	10.8 C	9.7 D	7.6 E		8.37A	7.11B	6.72C	5.64D	4.44E

T₁ Control, T₂ Sodium Benzoate 0.1% T₃ Sodium Benzoate 0.2% = T₄ Sodium Benzoate 0.5% = T₅ Potassium Sorbate 0.1%, T₆ Potassium Sorbate 0.2%, T₇ Potassium Sorbate 0.5%, T₈ Citric Acid 0.1%, T₉ Citric Acid 0.2%, T₁₀ Citric Acid 0.5%. a-o – means followed by different lowercase letters in the same column indicate significant differences (p < .05) between storage days, A-E – different uppercase letters in the same column indicate significant differences (p < .05) between the mean of the samples and in the same row indicate significant differences (p < .05) between the mean of the storage days values.

Texture

The data regarding mango concentrate texture is shown in Table 7. The storage has a significant effect on the texture of the concentrate. Similarly, treatments influenced the texture significantly (p < .05). The interactive effect of storage interval and treatment was also found to have significant effects (p < .05). The effects of storage indicate that the minimum texture values were observed at the beginning of the experiment and increased significantly (p < .05) during storage. The maximum increase in texture values was observed in T₁. The minimum increase in texture values was noted in T₇. The texture of concentrate was deteriorated due to the increase in total sugars and viscosity. According to the findings of Akhtar et al.,^[30] potassium sorbate preservative showed resistance to change in texture of citrus jam.

Taste

The results regarding the taste values are given in Table 8. The storage has a significant effect on mango concentrate texture. Similarly, treatments influenced the taste to a significant extent (p < .05). The interactive effect of storage interval and treatment was also found significant (p < .05). The effects of storage indicate that the maximum taste value was observed at the beginning of the experiment and decreased significantly (p < .05) during storage. The average taste values varied from 8.36 to 4.44. The maximum increase in taste values was noted in T₁, and the minimum increase was noted in T₇. The differences in taste from the start to the end of experiment were due to the increase in acidity of the concentrate in time. The microbial activity also plays a role in the fermentation of sugars which ultimately leads to the reduction of sweetness of mango concentrate during storage. The microbial fermentation also leads to an increase in acidity and decrease in pH of beverages (Janiaski et al.)^[38] Preservative treated sample showed better results as compared to the control.

Table 8. Effect of preservation methods on taste and overall appearance of mango concentrate during storage.

	Taste						Overall appearance
	0 day	15 days	30 days	45 days	60 days	Mean	0 day	15 days	30 days	45 days	60 days	Mean
T1	8.33 ± 0.58ab	6.48 ± 0.84fg	5.33 ± 0.58hi	3.67 ± 0.58kl	1.99 ± 0.01m	5.16E	8.15 ± 0.26abcd	6.82 ± 0.32fgh	5.63 ± 0.67ijk	3.63 ± 0.57no	2.67 ± 0.58p	5.01E
T2	8.33 ± 0.58ab	6.85 ± 0.79def	6.74 ± 0.51ef	4.67 ± 0.58ij	3.48 ± 0.50l	6.01D	8.33 ± 0.58abcd	7.17 ± 0.29efg	5.47 ± 0.81jkl	3.70 ± 0.42no	3.33 ± 0.58nop	5.60C
T3	8.33 ± 0.58ab	7.00 ± 0.87def	6.67 ± 0.58ef	5.67 ± 0.58gh	4.33 ± 0.58jkl	6.40C	8.33 ± 0.58abcd	7.45 ± 0.40def	5.67 ± 0.58ijk	3.60 ± 0.68nop	3.50 ± 0.60nop	5.71C
T4	8.33 ± 0.58ab	6.89 ± 0.77def	6.67 ± 0.58ef	5.72 ± 0.25gh	4.04 ± 0.61jkl	6.33C	8.59 ± 0.36ab	7.52 ± 0.50cdef	5.89 ± 0.84hijk	3.67 ± 0.58no	3.33 ± 0.58nop	5.80C
T5	8.25 ± 0.44abc	7.44 ± 0.12cde	6.93 ± 0.12def	6.33 ± 0.58fg	4.78 ± 0.38ij	6.75B	8.33 ± 0.58abcd	8.89 ± 0.57abcde	7.10 ± 0.67bcdef	6.33 ± 0.58ghij	4.67 ± 0.58lm	7.06B
T6	8.17 ± 0.29abc	7.65 ± 0.30bcd	7.14 ± 0.31def	6.67 ± 0.58ef	5.33 ± 0.58hi	6.99B	8.66 ± 0.30a	7.67 ± 0.58bcdef	7.67 ± 0.58bcdef	6.48 ± 0.84ghi	4.96 ± 0.06kl	7.09B
T7	8.35 ± 0.60ab	8.33 ± 0.58ab	8.33 ± 0.58ab	8.17 ± 0.29abc	8.15 ± 0.26abc	8.27A	8.67 ± 0.58a	8.33 ± 0.58abcd	8.41 ± 0.53abc	8.37 ± 0.55abcd	8.33 ± 0.58abc	8.42A
T8	8.48 ± 0.50ab	7.40 ± 0.35cde	6.33 ± 0.58fg	4.33 ± 0.58jkl	3.48 ± 0.50l	6.00D	8.29 ± 0.50abcd	6.33 ± 0.58ghij	5.48 ± 0.50jkl	3.67 ± 0.58no	2.79 ± 0.70op	5.31D
T9	8.59 ± 0.52a	6.63 ± 0.55ef	6.33 ± 0.58fg	5.33 ± 0.58hi	4.51 ± 0.50ijk	6.28C	8.19 ± 0.32abcd	6.51 ± 0.89ghi	5.33 ± 0.58kl	3.85 ± 0.25mn	2.82 ± 0.74op	5.34D
T10	8.48 ± 0.50ab	6.33 ± 0.58fg	6.67 ± 0.58ef	5.67 ± 0.58gh	4.33 ± 0.58jkl	6.30C	8.00 ± 0.87abcd	6.83 ± 0.29fg	5.45 ± 0.51jkl	3.67 ± 0.58no	3.80 ± 0.72mn	5.55D
Mean	8.36A	7.10B	6.71C	5.62D	4.44E		8.35A	7.25B	6.31C	4.70D	4.02E

Overall appearance

The results regarding the overall appearance of mango concentrate are shown in Table 8. The storage has a significant effect on the overall appearance of mango concentrate. Similarly, treatments influenced the overall appearance to a significant extent (p < .05). The interactive effect of storage interval and treatment was also found significant (p < .05). The effects of storage indicate that the maximum overall appearance values were observed at the beginning of the experiment and decreased significantly (p < .05) during storage. The average overall appearance values varied from 8.35 to 4.02 during storage. The maximum increase in overall appearance values of mango concentrate was noted in T₁, while the minimum increase was noted in T₇. Overall appearance was higher at beginning of the experiments and gradually decreased in time due to the increase in polyphenol oxidase activity and inversion of sugars that results in lower flavor, taste, and overall appearance scores (Janiaski et al.)^[38] The potassium sorbate showed good results for the retention of mango concentrate appearance during storage by reducing the loss of phytochemicals.

Principal component analysis (PCA)

The graphic of the PCA is presented in Figure 1 and shows that the first component (PC1) explained 82.78% of the total variability, while the second one (PC2) explained 12.97% of the total data variation (95.74%). PC1 was associated with viscosity, total sugars, total soluble solids, moisture content, DPPH, total phenolic, and total flavonoid contents. PC2 was associated with the pH and titratable acidity. It highlighted a high correlation of the samples in function of the storage days: the samples after 0 and 7 days of storage are located in the left quadrants, while the samples after 30, 45, and 60 days are positioned in the right part of the graphic. Multivariate comparisons clearly indicated the correlation between the studied parameters and their relationship with different mango concentrate preservatives during the storage days. Similarly, other authors corroborate the findings generated in this study.^[39]

Figure 1. Samples (blue circles) and variables (red circles) PCA biplot: T1-T10 - Control samples, T1-T10_15,30,45,60 - mango concentrates samples at 15, 30, 45, and 60 days.

Conclusion

It is concluded that viscosity, total sugars, reducing sugars, non-reducing sugars, titratable acidity and TSS were increased during storage in all treatments, except T₇ (potassium sorbate 0.5% concentration). On the other hand, the moisture contents, pH, DPPH radical scavenging activity, total phenolic contents, total flavonoids contents gradually decreased during 60 days of storage. Sensory evaluation (texture, taste and overall appearance) also showed some decreases in all treatments, except T₇. However, the findings showed that T₇ potassium sorbate (0.55 concentration) is the best among all the preservatives to increase the storage stability of mango concentrate. These results could be useful for the fruits processing industry to optimize the preservation methods of the mango fruits.

Author’s contribution

Muhammad Samiullah Awan1, Asif Ahmad, Waseem Khalid: methods and investigation.

Muhammad Zubair Khalid, Ionica Coţovanu, Farhan Afzal, Suliman Yousef Alomar: conceptualization, funding acquisition and writing of original draft.

Felix Kwashie Madilo, Shazia Yaqub, Manal Hadi Ghaffoori Kanaan, Sura Saad Abdullah: writing, reviewing, editing and approving

Acknowledgments

The authors are thankful to PMAS Arid Agriculture University Rawalpindi, Pakistan for providing the research facilities used for this study. The authors also would like to thank the Researchers Supporting Project Number (RSP2023R35), King Saud University, Riyadh, Saudi Arabia.

Disclosure statement

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

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.