Optimizing packaging and storage conditions for osmotically dehydrated aonla (Emblica officinalis L.) segments

Introduction

Aonla (Emblica officinalis L.) commonly known as Indian gooseberry, is a significant minor fruit crop in India, valued for its exceptional nutritional, medicinal and economic properties. The total sugars content in aonla fruit varies from 7 to 9.6%, reducing sugars from 1.04 to 4.09% and non-reducing sugars from 3.05 to 7.23% among the various varieties. Despite its nutritional benefits, fresh aonla faces significant challenges in post-harvest handling and storage, leading to considerable waste. Consequently, there is a pressing need to explore more effective preservation techniques that maintain the fruit's health benefits and market appeal. Osmotic dehydration has emerged as a promising solution to enhance the shelf life and quality of aonla. This method involves immersing the fruit in concentrated solutions, allowing for water removal while preserving its nutritional value and sensory characteristics. Given the increasing consumer demand for natural health-promoting products and the need for efficient post-harvest management, research into the packaging and storage stability of osmotically dehydrated aonla products is both timely and essential. This thesis explores the physico-chemical and sensory characteristics of aonla segments subjected to osmotic dehydration and stored under different packaging and temperature conditions, with the goal of extending shelf life while preserving quality. Dehydrated fruits are becoming more and more popular and profitable because of their inherent benefits, which include longer shelf life, increased resistance to bacterial attack and cheaper handling, storage and transportation expenses.

Materials and Methods

Preparation of samples

The selected fruits were washed with tap water, blanched for 10-12 minutes to reduce the enzyme activity and also for easy removal of seeds and then dipped in 2 per cent salt solution to remove the astringency. Seeds and segments were removed manually and subjected to osmotic dehydration. Pre-processed aonla analysed for physicochemical characteristics. The moisture content was determined by direct heating in a drying oven at 105 °C for 48 hrs according to the AOAC method (AOAC, 1990) [1] . The initial average values for the main characteristics of the pre-processed aonla are shown in Table 3.1. The osmotic solution utilized in experiment was prepared by mixing food-grade sucrose with distilled water. To maintain the osmotic solution-to-fruit ratio at 3:1, care was taken to prevent dilution of the osmotic solution due to water removal during the experimental runs. This ratio was critical in ensuring a consistent osmotic driving force throughout the process.

Osmotic dehydration

A sugar syrup with a concentration of 55°Brix was prepared by mixing 1 kg of sugar with 1 kg of water. The concentration was adjusted as needed by heating or adding more sugar. Once the syrup had cooled, 0.1% each of potassium metabisulphite and sodium metabisulphite used as preservatives and anti-browning agents were dissolved in a small amount of drinking water and mixed into the syrup To study osmosis the samples were kept in sugar syrup at room temperature for 72 hours for osmosis in a vessel and after that kept for draining for 12 hours. Osmotic dehydration characteristics of aonla fruit segments in sugar syrup of 55° Brix concentration and temperature 20-30 °C were studied by immersing 1 kg of aonla segments by three times its weight of syrup (sample: syrup ratio :: 1: 3) kept in a vessel.

Tray-drying

On a perforated aluminum tray approximately 12 kg of osmosed aonla fruit samples were evenly distributed in a single layer and allowed to dry for duration of 10-12 hours. Only after the drying chamber's temperature had steadied to the necessary level was the tray placed inside the tray dryer. After taking the sample out of the dryer for approximately ten minutes the weight of the sample was periodically measured with an electric balance (0.01 g precision). The samples were dried allowed to cool and then promptly placed within packaging bags.

Packaging

A well dehydrated aonla fruit sample containing below 16 per cent were packed into the desired packaging material (High Density Polyethylene, Low density polyethylene, Brown paper bags & Laminated Aluminum pouch) for further treatment & storage studies. Each packaging samples packed with sample size 100gm osmotically dehydrated aonla segments.

Storage

Thermally sealed packaging bags were stored at different temperatures, room temperature (32 °C) and refrigerated temperature (0-5 °C). This study aimed to analyze the suitability of these temperatures for long-term storage without compromising the nutritional and textural quality of the product.

Treatment combination

Experiment studies were done by treating samples with the following treatments combinations.

Results and Discussion

Physico-chemical parameters of aonla fruit

The physico-chemical properties of fresh aonla fruits used for preparing osmotically dehydrated segments are presented in Table 4.1. The data reveal that the average weight of the fresh aonla fruits is around 30 grams, with a slight variation of ±0.90 grams and the average diameter is approximately 3.90 cm, with a variation of ±0.21 cm. The seeds constitute about 9.00% of the fruit's total weight. Regarding chemical composition, the fruits have an average total soluble solids (TSS) content of 10.20% (±0.87%). The total sugar content is about 6.93%, with reducing sugars contributing 5.58% (±0.35%) and non-reducing sugars 3.50% (±0.20%). The acidity is recorded at 2.23% with a minimal variation of ±0.010%, while the ascorbic acid content averages 361.97 mg per 100 grams, with a variation of ±3.7 mg. These results are consistent with the findings of Kumar et al. (2019) [13] and Sumitha et al. (2015) [25] . Total Soluble solid of prepared products shows increasing trend during storage (Table 3.2). Statistically significant differences were observed for total soluble solid content in osmotically dehydrated aonla segments due to storage temperature, different packaging material and interaction between temperature and packaging material. Further, dried aonla segments samples recorded higher content of total soluble solid (83.75%) at initial stage of storage.

In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was increase in the total soluble solid content of the samples. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. Maximum total soluble sugar found in brown paper bag (87.25%) packaging material over 90 days of storage. In case of temperature, significantly highest (86.27%) total soluble solid was observed in samples stored at room temperature. In general, there was gradual increase (82.30 to 87.25%) in total soluble solid content in all the samples during the 3 months of storage as compared to initial. The samples stored at refrigerated temperature (0-5 °C) had less increase (83.42 to 83.11%) in total soluble solid than those stored at room temperature (Table 3.2), might be due to limitation in conversion of polysaccharides into soluble sugar and also, oxygen free micro-environment might have prevented the oxidation reduction reaction. These findings are in alignment with the observations of Argaiz et al. (1994) [3] and Islam et al. (2019) [11] in osmotically dehydrated papaya cubes, as well as Mali (1997) [14] , Palve (2002) [17] and Gawade (2002) [8] in dried figs. Similar trends were also supported by the research of Sumitha et al. (2015) [25] and Bidwe et al. (2024) [4] .

Ascorbic acid

Ascorbic acid content of aonla segments shows gradual decrease during storage (Table 3.2). Statistically significant differences were observed for ascorbic acid content in osmotically dehydrated aonla segments due to storage temperature, different packaging material and interaction between temperature and packaging material. Further, dried aonla segments samples recorded higher content of ascorbic acid (217.45 mg/100g) at initial 30 days of storage in laminated aluminium pouch at refrigerated temperature. In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was decrease (217.88 to 213.34%) in the ascorbic acid content of the samples. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. In case of temperature, significantly highest (215.04%) ascorbic acid was observed in samples stored at refrigerated temperature for 90 days of storage. In general, there was gradual decrease in ascorbic acid content in all the samples during the 3 months of storage as compared to initial. The samples stored at refrigerated temperature (0-5 °C) had less decrease (217.88 to 213.50%) in ascorbic acid than those stored at room temperature (217.02 to 213.30%) (Table 3.2), might be due to limitation in oxidation of aonla segments. The decrease in ascorbic acid might be due to oxidation of aonla segments. Similar findings have been reported by Da et al. (2018) in dried papaya, Chandra and Kumara (2015) [5] in osmotically dehydrated papaya, Thonta and Patil (1988) [26] , Pawar et al. (1992) [18] in dried figs, as well as by Bidwe et al. (2024) [4] and Sumitha et al. (2015) [25] in osmotically dehydrated aonla segments.

Acidity

Table 3.2 presents the data on the effect of various treatments on the acidity of osmotically dehydrated aonla segments stored under room and refrigerated conditions. The results clearly indicate a declining trend in acidity across all treatments as the storage period advanced from 0 to 90 days. Further, dried aonla segments samples recorded higher content of acidity (1.13%) at initial 30 days stage of storage. In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was decrease (1.13 to 1.08%) in the acidity content of the samples. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. Minimum acidity (1.05%) found in low density polyethylene over 90 days of storage. In case of temperature, significantly highest (1.10%) acidity was observed in samples stored at room temperature.In general, there was gradual decrease in acidity content in all the samples during the 3 months of storage as compared to initial 30 days stored sample. The samples stored at refrigerated temperature (0-5 °C) had less decrease in acidity (1.11 to 1.05%) than those stored at room temperature (1.13 to 1.08%) (Table 3.2). The decrease in acidity might be due to cellular changes and breakdown of organic acids. These findings align with those reported by Chandra and Kumara (2015) [5] , Rohani et al. (1997) [21] , Hazarika et al. (2017) [10] , Othman (2009), Sumitha et al.

(2015) [25] and Bidwe et al. (2024) [4] in similar studies on osmotically dehydrated and stored papaya and aonla.

Moisture

Moisture of prepared products gradually declined during storage (Table 3.3). Statistically significant differences were observed for moisture content in osmotically dehydrated aonla segments due to storage temperature, different packaging material and interaction between temperature and packaging material. Further, dried aonla segments samples recorded higher content of moisture (16.63%) at initial 30 days stage of storage in laminated aluminium pouch. In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was decrease in the moisture content of the samples. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. In case of temperature, significantly highest (13.53%) moisture was observed in samples stored at refrigerated temperature at 90 days of storage. In general, there was gradual decrease (16.63 to 11.58%) in moisture content in all the samples during the 3 months of storage as compared to initial 30 days stored sample. The samples stored at refrigerated temperature (0-5 °C) had less decrease in moisture than those stored at room temperature (Table 3.3). The decrease in moisture might be due to water activity reduction and osmosis. These findings are consistent with those reported by Sagar et al. (1999) [22] in mango slices, Thonta and Patil (1988) [26] , Pawar et al.

(1992) [18] in dried figs and Gharate (1984) [9] in ber candy, as well as Sumitha et al. (2015) [25] and Bidwe et al. (2024) [4] in osmotically dehydrated aonla and papaya segments.

The results fall within the expected range reported in earlier literature.

Reducing sugar

Reducing sugar of prepared products shows increasing trend during storage (Table 3.3). Statistically significant differences were observed for reducing sugar content in osmotically dehydrated aonla segments due to storage temperature, different packaging material and interaction between temperature and packaging material. Further, dried aonla segments samples recorded higher content of reducing sugar (49.58%) at initial 30 days of storage. In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was increase (48.15 to 52.51%) in the reducing sugar content of the samples. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. In case of temperature, significantly highest (51.35%) reducing sugar was observed in samples stored at room temperature at 90 days of storage. In general, there was gradual increase in reducing sugar content in all the samples during the 3 months of storage as compared to initial. The samples stored at refrigerated temperature (0-5 o C) had less increase in reducing sugar than those stored at room temperature (Table 3.2), might be due to limitation in Inversion of Sucrose and also, Cellular Breakdown of polysaccharides into simple sugar. The increase in reducing sugar might be due to Inversion of Sucrose and also, Cellular Breakdown of polysaccharides into simple sugar. These results are supported by similar findings reported by Narayana et al.

(2002) [15] in stored banana, Shivani et al. (2020) [24] in papaya powder, Thonta and Patil (1988) [26] , Pawar et al.

(1992) [18] in dried figs, Bidwe et al. (2024) [4] in papaya and Sumitha et al. (2015) [25] in osmotically dehydrated aonla segments.

Non reducing sugars

Non reducing sugar of prepared products gradually declined during storage (Table 3.3). Statistically significant differences were observed for non reducing sugar content in osmotically dehydrated aonla segments due to storage temperature, different packaging material and interaction between temperature and packaging material. Further, dried aonla segments samples recorded higher content of non reducing sugar (20.50%) at initial 30 days stage of storage.

In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was decrease (20.50 to 17.30%) in the non reducing sugar content of the samples. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. In case of temperature, significantly highest (18.70%) non reducing sugar was observed in samples stored at refrigerated temperature. In general, there was gradual decrease in non reducing sugar content in all the samples during the 3 months of storage as compared to initial 30 days stored sample. The samples stored at refrigerated temperature (0-5 o C) had less decrease in non reducing sugar than those stored at room temperature (Table 3.2). The decrease in non reducing sugar might be due to Hydrolysis of Sucrose and enzymatic activity. these findings are in agreement with previous studies by Thonta and Patil (1988) [26] , Pawar et al. (1992) [18] in dried figs, Gharate (1984) [9] in ber candy and by Sumitha et al. (2015) [25] and Bidwe et al. (2024) [4] in osmotically dehydrated aonla and papaya, respectively. The results fall within the expected range reported in earlier research.

Total Sugars

Total sugar of prepared products shows increasing trend during storage (Table 3.3). Statistically significant differences were observed for total sugar content in osmotically dehydrated aonla segments due to storage temperature, different packaging material and interaction between temperature and packaging material. Further, dried aonla segments samples recorded higher content of total sugar (67.20%) at initial 30 days of storage in high density polyethylene. In case of osmotically dehydrated aonla segments it was found that with passing of storage period (1, 2 and 3 months) there was increase (66.91 to 68.74%) in the total sugar content of the samples in brown paper bag. After 3 months storage of the osmotically dehydrated aonla segments shreds significant differences were observed due to variations in temperature and interaction between temperature and packaging. Maximum total sugar found in brown paper bag (69.17%) packaging material over 90 days of storage. In case of temperature, significantly highest (69.30%) total sugar was observed in samples stored at room temperature for 90 days of storage. In general, there was gradual increase (67.20 to 69.94%) in total sugar content in all the samples during the 3 months of storage as compared to initial. The samples stored at refrigerated temperature (0-5 o C) had less increase in total sugar (66.52 to 68.34%) than those stored at room temperature (66.59 to 69.94%) (Table 3.4), might be due to limitation in degradation of polysaccharides and also, hydrolysis of Sucrose. The increase in total sugar might be due to degradation of polysaccharides and hydrolysis of sucrose. These findings are consistent with those reported by Jain et al. (2011), Thonta and Patil (1988) [26] , Pawar et al. (1992) [18] in dried figs and Sumitha et al. (2015) [25] and Bidwe et al. (2024) [4] . [17] and Pokharkar (1994) in pineapple slices. Findings by Sumitha et al. (2015) [25] and Bidwe et al. (2024) [4] in osmotically dehydrated aonla and papaya also support these results. Taste scores were significantly higher in samples stored at refrigerated temperatures, with notable variations due to differing storage conditions. Aonla segments stored in laminated aluminum pouches at refrigerated temperatures were rated superior at one, two and three months. Previous research indicates that factors affecting osmotic dehydration kinetics, along with the final ratio of water loss to sugar gain, greatly influence product characteristics, resulting in improved quality through osmotic dehydration. Total sensory score values ranged from 8.40 to 9.0 during the initial 30 days of storage, with all sensory evaluations rated from good to very good. However, sensory scores decreased during subsequent storage periods, although treatments P4S2 (8.8), P4S1 (8.54) and P2S2 (8.45) maintained their superiority after three months of storage, indicating high acceptability. Sensory scores were consistently higher for samples stored at refrigerated temperatures compared to room temperature and scores tended to decline with increased storage duration. This decline may be attributed to slower chemical reactions at lower temperatures, which helped preserve the product's texture and colour, enhancing overall sensory scores. The observed decline in taste over the storage period can be attributed to chemical changes such as degradation of flavour compounds, loss of volatiles and possible oxidation of sensitive ingredients, which may reduce overall sensory appeal. The interaction between treatment and storage duration was statistically significant, particularly at 90 days. These findings align with those reported by Chaturvedi et al.

(2016) [6] in osmotically dehydrated papaya, Palve (2002) [17] in dried figs, Sumitha et al. (2015) [25] in aonla and Bidwe et al. (2024) [4] . The aonla segments packed in laminated aluminum pouches and stored at refrigerated temperatures (P4S2) achieved superior sensory scores, likely due to the packaging's low permeability and reduced biochemical activity at cooler temperatures, which led to lower nonenzymatic browning and limited oxygen availability. These findings align with research by Amitabh et al. (2000) [2] on mango, Pragati and Dahiya. (2003) on aonla, Sharma et al.

(2004) [3] on apricot and Kumar and Sagar (2009) [12] on mango slices.

Conclusion

The findings of the present study indicate that storage conditions play a crucial role in determining the quality of osmotically dehydrated aonla segments. Among the treatments, samples kept under refrigeration, especially when packed in laminated aluminum pouches, maintained superior quality throughout the storage duration.

References

1. AOAC. Official Methods of Analysis. 15th ed. Association of Official Analytical Chemists, Washington, D.C.; 1990.
2. Amitabh, Singh RD, Tomar MC. Studies on osmotic dehydration of some varieties of ripe mangoes grown in Uttar Pradesh. Indian Food Packer. 2000;54(3):66-72.
3. Argaiz A, Lopez-Malo A, Palou E, Welti J. Osmotic dehydration of papaya with corn syrup solids. Drying Technology. 1994;12(7):1709-1725.
4. Bidwe GG, Patil RA, Swami MR, Sarvade PB, Chapke RP, Ghule VV, Gavhane YD. Optimization of packaging and storage conditions to enhance the chemical stability of osmotically dehydrated papaya (Carica papaya L.) cubes. International Journal of Advanced Biochemistry Research. 2024;SP8(10):1402-1407.
5. Chandra S, Kumara D. Recent development in osmotic dehydration of fruit and vegetables: A review. Food Science and Nutrition. 2015;55:552-561.
6. Chaturvedi S, Gupta A, Arora S, Balani S, Jalan S. Osmotic dehydration of papaya: Optimization and comparison. National Conference on Advances in Food Science & Technology. 2016; p.103-107.
7. Da Silva JEV, de Melo LL, de Medeiros RAB, Barros ZMP, Azoubel PM. Influence of ultrasound and vacuum assisted drying on papaya quality parameters. Food Science and Technology. 2018;97:317-322.
8. Gawade MH. Studies on drying and storage of fig (Ficus carica L.) fruits [M.Sc. thesis]. Rahuri: Mahatma Phule Krishi Vidyapeeth; 2002.
9. Gharate AN. Studies on preparation of candy from ber [M.Sc. thesis]. Rahuri: Mahatma Phule Krishi Vidyapeeth; 1984.
10. Hazarika TK, Lalthanpuii, Mandal D. Influence of edible coatings on physico-chemical characteristics and shelf-life of papaya (Carica papaya) fruits during ambient storage. Indian Journal of Agricultural Sciences. 2017;87(8):1077-1083.
11. Islam MZ, Das S, Monalisa K, Sayem ASM. Influence of osmotic dehydration on mass transfer kinetics and quality retention of ripe papaya (Carica papaya L.) during drying. Journal of Food Processing and Preservation. 2019;1:0-14.
12. Kumar SP, Sagar VR. Influence of packaging material and storage temperature on quality of osmo-vac dehydrated aonla segments. Journal of Food Science and Technology. 2009;46(3):259-262.
13. Kumar S, Gehlot R, Singh R, Rekha, Sindhu R, Arora S. Physico-chemical characteristics of fresh aonla and papaya fruits. International Journal of Chemical Studies. 2019;7(3):2186-2188.
14. Mali BB. Effect of methods of preparation and storage on quality of dried figs [M.Sc. thesis]. Rahuri: Mahatma Phule Krishi Vidyapeeth; 1997.
15. Narayana CK, Rao SK, Reddy K. Shelf life and quality of fruits in different polybag conditions. Postharvest Biology and Technology. 2002;23(3):147-155.
16. Othman OC. Physical and chemical composition of storage ripened papaya. Journal of Fruit Research. 2009;26(1):45-52.
17. Palve SS. Studies on preparation and storage of dried figs [M.Sc. thesis]. Rahuri: Mahatma Phule Krishi Vidyapeeth; 2002.
18. Pawar SG, Kulkarni DN, Shere DM, Kulkarni KD, Patil VK. Effect of pretreatments on chemical composition and drying rates of solar dried figs. Indian Food Packer. 1992;1:39-44.
19. Pokharkar SM. Studies on osmotic concentration and air drying of pineapple slices [Ph.D. thesis]. Kharagpur: Indian Institute of Technology; 1994.
20. Pragati S, Dahiya S, Dhawan SS. Effect of drying methods on nutritional composition of dehydrated aonla fruit (Emblica officinalis Gaertn.) during storage. Plant Foods for Human Nutrition. 2003;58(1):1-9.
21. Rohani MY, Lee J. Effects of controlled atmosphere on fruit storage life. Postharvest Science. 1997;12(2):8996.
22. Sagar VR, Khurdiya DS, Balakrishnan SP. Quality of dehydrated ripe mango slices as affected by packaging material and mode of packaging. Journal of Food Science and Technology. 1999;36(1):67-70.
23. Sharma KD, Kumar R, Kaushal BNL. Mass transfer characteristics, yield and quality of five varieties of osmotically dehydrated apricot. Journal of Food Science and Technology. 2004;41(3):264-275.
24. Shivani M, Mehta R, Reddy P. Nutrient retention in papaya powder: Comparison of packaging methods. Food Processing and Preservation. 2020;43(2):315-322.
25. Sumitha N, Tiwari RB, Patil RA. Suitability of packaging and storage conditions for osmo-air dried aonla segments. Proceedings of the National Academy of Sciences, India Section B: Biological Sciences. 2015;85(1):203-209.
26. Thonta GT, Patil VK. Studies on drying of fig fruits. Indian Food Packer. 1988;42(4):94-99.