Optimization of process parameters of refractance window drying for aonla slices and comparison with other drying techniques.

BACKROUND: Aonla is as a good source of antioxidants due to its high ascorbic acid and polyphenol contents. However, because of its high acidity and astringent taste, aonla is rarely consumed in its fresh form. As the constituents in aonla are heat sensitive, it is essential to find a suitable drying method for preservation. Therefore, refractance window drying (RWD) of aonla slices was studied as it has the potential of retaining heat-sensitive compounds. RESULTS: The effect of RWD process variables, namely water temperature (75, 82.5, 90 °C) and slice thickness (2, 4, 6 mm), on different quality parameters of dehydrated aonla was studied. Increasing water temperature resulted in significantly higher ascorbic acid content, titratable acidity and product temperature, while total phenolic content, free radical scavenging activity and moisture content decreased. With the exception of product temperature, higher slice thickness led to an increase in the values of all the parameters. At the optimized processing conditions of 83 °C water temperature and 4 mm slice thickness, the ascorbic acid content, total phenolic content, free radical scavenging activity, titratable acidity and moisture content values were found to be 269.03 mg (100 g)-1, 242.33 mg (100 g)-1, 87.11%, 3.62% and 4% respectively. The aonla slices subjected to RWD also possessed 4-6% higher phytochemical content than osmotically dried and hot-air-dried samples. CONCLUSION: This research highlights the effectiveness of RWD in preserving heat-sensitive compounds in food like aonla. The RW-dried slices had a smoother and more uniform microstructure compared to osmotically dried and hot-air-dried samples. © 2024 Society of Chemical Industry.

Effect of blended fermented beverages from blood fruit and aonla with two types of organic sweetener.

Fermented beverages from blood fruit (Haematocarpus validus Bakh.f.exForman) and aonla (Emblica officinalis Gaertn.) were prepared to find out the interactive effect between blending of different proportion of blood fruit and aonla along with two types of organic sugar (palm and cane sugar) to add the diversity to the drinks, preserve the nutrition, antioxidative and functional properties of the fruits and reduced the post harvest losses. The beverages have the following proximate compositions viz. a significantly highest TSS (8.36 °Brix), total sugar (2.29%), reducing sugar (1.92%), alcohol (9.02%) were recorded treatment combinations T3S1 (Blood fruit 90% + aonla 10% +palm sugar 20%). T2 (100% aonla) recorded highest ß-carotene (172.95 IU), titratable acidity (0.61%) and ascorbic acid (61.95 mg/100ml) while highest anthocyanin (12.98 mg/100 ml) were recorded in T1 (100% blood fruit). Similarly, the sensory evaluation shows that most of treatments (T1S1, T3S1, T3S2, and T4S2) were accepted by the panellists. Considering the findings of investigation and highest net monitory returns (5.84 B: C ratio) obtained, it can be conclude that blending of blood fruit and aonla at different proportion with different types of sugar has a good prospect for commercialization.

Effect of pressure and time on bioactive content, PPO inactivation, physicochemical and sensory properties of aonla (Emblica officinalis) juice during hydrodynamic cavitation processing.

Physical and nutritional attributes of aonla juice treated with hydrodynamic cavitation (HC) at a pressure range of 5-15 psi and time between 5 to 30 min were evaluated. Based on maximum retention of bioactives, antioxidant activity, inactivation of polyphenol oxidase (PPO), and physicochemical properties, HC conditions were optimized at 10 psi for 15 min, based on retention of 92.19% antioxidant activity, 88.01% vitamin C, and 96.80% of total phenolic content. Improved sedimentation index and viscosity were noted due to HC processing. The color profile of HC-treated samples was improved with less browning (63.86) and yellowing index (14.79) than that of control (browning index 64.61). Thermally treated samples inactivated 100% of PPO at 95 ℃ for 3 min, however, formation of a dark color with a browning index value of 67.38 was noted. The retention of various bioactives in thermally treated juice samples was much lesser than that of HC-treated samples. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-022-01164-2.

Stabilization and attributive amelioration of sugarcane juice by naturally derived preservatives using aonla and moringa extract.

Sugarcane juice (SCJ) is a cheap, popular, and very nutritious beverage served at roadside stalls in many countries during harvesting season. The juice is normally consumed immediately after extraction as fermentation sets within a few hours of extraction. Preserving the raw sugarcane juice is always challenging because it spoils within a few hours of extraction due to fermentation. Therefore, the bottling, distribution, and marketing of sugarcane are difficult tasks. The present study was designed to investigate the effect of naturally derived preservatives using aonla extract (AE) and moringa extract (ME) in different proportions (0%, 3%, 5%, and 7%) for the preservation of SCJ during 21 days of the storage period at 4 ± 2°C temperature. The effect of extracts and storage time were analyzed on physicochemical parameters, bioactive compounds, enzymatic, microbiological, and sensory analyses of SCJ. A significant improvement in pH of 5% AE (5.30 ± 0.06) and 5% ME (5.36 ± 0.02) was observed at 21 days as compared to control (5.89 ± 0.02). The total phenolic contents in 7% ME were also observed to be retained (4.4 ± 0.02 mg GAE/mL) at 21 days as compared to control (2.65 ± 0.03 mg GAE/mL). Other physicochemical and phytochemical analyses including titratable acidity, total soluble solids, total flavonoids, ascorbic acid, 2,2-Diphenyl-2-picrylhydrazyl (DPPH), and ferric reducing antioxidant power assay (FRAP) also indicated that SCJ treated with ME was significantly stable (p < .05) regarding quality parameters, nutritional and sensory attributes at different storage intervals. These findings may be practical for the large-scale production, storage, and marketing of SCJ products.

Potentiality of freeze-thaw treatment to produce soft textured aonla (Emblica officinalis) candies.

Aonla, due to its astringency, is converted into various processed products. Candy is the most popular of among them. Commercially available aonla candies in India are hard in texture. However, soft textured candies are preferred more over harder ones. Hence, study was undertaken to produce soft textured candies. Whole fruits and fruit segments were blanched in boiled water, frozen in domestic freezer for 12 h and thawed at room temperature (15-20 °C). Fresh, blanched, frozen and thawed samples were subjected to textural analysis. Some of the blanched and thawed segments were used to prepare candies and subjected to textural analysis. Results indicated that force-deformation behavior of all samples differed significantly. Fresh, blanched, thawed and frozen segments required 14.39, 0.84, 0.22 and 0.18 N force, respectively to compress them till 1 mm deformation. Similarly, peak force (5 mm deformation) was maximum in fresh segments (172.25 N) followed by blanched (8.77 N), frozen (1.06 N) and thawed (0.85 N). Peak force values for control and soft candies were 13.14 and 6.86 N, respectively. Based on results, it was found that freeze-thaw treatment significantly reduced the firmness of segments and produced soft textured candies.

Assessment of total polyphenols, antioxidants and antimicrobial properties of aonla varieties.

Phenolic content, antioxidant activities and antimicrobial activities of methanolic, ethanolic and ethyl acetate extracts of five different varieties of aonla (Emblica officinalis) fruits as well their powders were evaluated. Total polyphenolic content in fresh aonla fruit extracts varied from 70.6 to 159.4 mg GAE/g and their EC 50 (effective concentration) values for antioxidant activity ranged from 46.72 to 359.7 µg/ml. Significant varietal difference were observed in antioxidant activity of the extracts of fresh aonla fruit and powder. Among the variety analyzed, Desi variety exhibited significantly higher TPC (total polyphenol content) and antioxidant activity in fresh as well as dried form in all the extracts. Methanolic extracts of various varieties had maximum TPC and antioxidant activity. Variety NA-7 showed high TPC and antioxidant activity. Almost, similar trend was observed among the extracts of aonla powders for TPC and AOA (antioxidant activity). A high positive correlation coefficient existed between TPC and AOA of different aonla extracts. All the extracts analyzed, exhibited a strong antimicrobial potential against E. coli, Salmonella typhi, Staphylococcus aureus and Candida albicans. This study suggests aonla as potential natural source of antioxidants and antimicrobial agents.

Drying kinetics and physico-chemical characteristics of Osmo- dehydrated Mango, Guava and Aonla under different drying conditions.

Mango (Mangiferra indica L), guava (Psiduim guajava L.) slices and aonla (Emblica officinalis L) segments were osmo-dried under four different dying conditions viz., cabinet drier (CD), vacuum oven drier (VOD), low temperature drier (LTD) and solar drier (SD) to evaluate the best drying condition for the fruits. It was found that vacuum oven drying was superior to other mode of drying as it holds maximum nutrients like acidity, ascorbic acid, sugar and water removal and moisture ratio of products. It was found through regression analysis that drying ratio and rehydration ratio was also superior in vacuum drying followed by cabinet drying. In addition, descriptive analysis on sensory score was also found best with vacuum drying while the Non-enzymatic browning (NEB), which is undesirable character on dried product, was more with solar drier.

Effect of blanching on thin layer drying kinetics of aonla (Emblica officinalis) shreds.

The effect of hot water blanching treatment on thin layer drying kinetics of aonla shreds was studied at drying air temperatures of 50, 55 and 60 °C with the air velocity of 1.2 m/s. The drying time decreased with the increase in air temperature and blanching. The drying process was observed in falling rate. Drying after blanching reduced the vitamin C content of aonla shreds by 69.36% whereas it decreased by 27.78% in unblanched shreds. Eight commonly used mathematical models were evaluated to predict the drying behavior of aonla shreds. The Midilli model described the drying behaviour of unblanched aonla shreds at all temperatures better than other models whereas two-term model described the drying kinetics of blanched aonla shreds satisfactorily. The effective diffusivities of the unblanched and blanched aonla shreds were determined using Fick's law of diffusion. The activation energy was found to be 47.21 kJ/mol for unblanched and 43.98 kJ/mol for blanched aonla shreds.

Effect of pretreatment and drying methods on quality of value-added dried aonla (Emblica officinalis Gaertn) shreds.

Value added dried Indian gooseberry (aonla) shreds were prepared using aonla fruits of cv. 'NA-7'. Two blanching methods (hot water and potassium metabisulphite (KMS) at 0.1%) and two drying methods (solar and hot air oven drying) were tried for the production of aonla shreds. Common salt, black salt and ginger juice were mixed for enhancing sensory quality of the product. The best product was obtained with KMS blanching and drying in solar dryer with added common salt at 3%. The most acceptable product had ascorbic acid content 298.3 mg/100 g, tannin 2.4%, acidity 2.6%, reducing sugar 3.0%, non-reducing sugar 21.0% and total sugar 24.0%. The recovery was 8.0-8.5%.

Effect of pasteurization temperature on quality of aonla juice during storage.

A study was carried out to detect the changes in colour and quality attributes of aonla juice during storage after pasteurization at different temperatures. After extracting juice from aonla cv. Chakaiya, it was pasteurized at five different temperatures and preserved with 500 ppm SO2 in PET bottles under ambient conditions. Juice was periodically analysed for colour and chemical characters up to 9 months of storage. Though the contents of ascorbic acid and polyphenols in juice decreased with increase in storage period, the effect of pasteurization temperature was not significant. High degree of browning was observed in juice heated at higher temperatures (90 and 95 °C) as compared to lower temperatures (75 and 80 °C) throughout the storage period as indicated by increase in NEB values. The degree of browning was further confirmed by higher negative numerical values of whiteness index in Hunter's scale for intensity of colour. HPLC data indicated that content of gallic acid in juice decreased initially but increased sharply as the storage period prolonged. Higher amount of gallic acid was detected after 9 months of storage in juice pasteurized at 95 °C than in juice heated at 75 °C. The contents of kaempferol and caffeic acid decreased throughout the storage period irrespective of pasteurization temperature. Though least browning was observed in juice pasteurized at 75 °C, but microbial growth was observed after 9 months of storage. Hence, pasteurization temperature of 80 °C was found optimum for preservation of aonla juice under ambient conditions.

Sorption isotherm characteristics of aonla flakes.

The equilibrium moisture content was determined for un-osmosed and osmosed (salt osmosed and sugar osmosed) aonla flakes using the static method at temperatures of 25, 40,50, 60 and 70 °C over a range of relative humidities from 20 to 90%. The sorption capacity of aonla decreased with an increase in temperature at constant water activity. The sorption isotherms exhibited hysteresis, in which the equilibrium moisture content was higher at a particular equilibrium relative humidity for desorption curve than for adsorption. The hysteresis effect was more pertinent for un-osmosed and salt osmosed samples in comparison to sugar osmosed samples. Five models namely the modified Chung Pfost, modified Halsey, modified Henderson, modified Exponential and Guggenheim-Anderson-de Boer (GAB) were evaluated to determine the best fit for the experimental data. For both adsorption and desorption process of aonla fruit, the equilibrium moisture content of un-osmosed and osmosed aonla samples can be predicted well by GAB model as well as modified Exponential model. Moreover, the modified Exponential model was found to be the best for describing the sorption behaviour of un-osmosed and salt osmosed samples while, GAB model for sugar osmosed aonla samples.

Response surface optimization of osmotic dehydration process for aonla slices.

Response surface methodology was used to investigate the effect of sugar concentration (50-70° Brix), solution temperature (30-60°C), solution to fruit ratio (4:1-8:1) and immersion time (60-180 min) on the water loss, solute gain, rehydration ratio, vitamin-C loss, colour change and sensory overall acceptability of Indian gooseberry (aonla) slices. The optimum process parameters obtained by computer generated response surfaces, canonical analysis and contour plot interpretation were: sugar concentration, 59° Brix solution temperature 51°C, solution to fruit ratio 4:1 and immersion time of 60 min.

Effect of zero energy cool chamber and post-harvest treatments on shelf-life of fruits under semi-arid environment of Western India. Part 2. Indian gooseberry fruits.

Effect of zero energy cool chamber (ZECC) along with post-harvest treatments including CaCl2, mustard oil and K2SO4 separately on shelf-life and fruit quality attributes of Indian gooseberry or aonla (Emblica officinalis Gaertn) during storage under semi-arid ecosystem of Gujarat was studied. Increase in physiological loss in weight (PLW), spoilage loss, total soluble solids, total sugar and reducing sugars, reduction in titratable acidity and ascorbic acid were observed during storage period in all the treatments. Fruits treated with 1.5% CaCl2 and stored in ZECC recorded least PLW (16%), spoilage loss (16.5%), respiratory activity (83 mg CO2 /kg/h) and exhibited 11 days of shelf-life, while untreated control had 6 days economic life. It was closely followed by 1% CaCl2 + ZECC treatment. Fruits stored in ZECC recorded 9 days shelf-life. Highest respiration rate was in control (88.1 mg CO2 /kg/h) on 13(th) day of storage. It may be concluded that 1.5% CaCl2 and storage in ZECC treatment was found most efficient to retain the fruit quality attributes till 13(th) day of storage under semi-arid environment of western India.

Effect of open air drying, LPG based drier and pretreatments on the quality of Indian gooseberry (aonla).

The aonla fruits (whole fruit, pricking, splits, segments) were subjected to pretreatments like blanching, osmotic dehydration with salt (2%) and sugar (40%) in different experiments before drying to obtain a product with better keeping quality. An LPG based drier (CRIDA drier) with capacity to dry 50 kg of fresh Indian gooseberry (aonla) was used. Nutritional quality and rehydration characteristics of CRIDA drier dried products were higher and free from contamination. Drying time was shortest for blanched and osmotically dehydrated segments dried in CRIDA drier and the product had better vitamin C retention, rehydration characteristics and sensory acceptability compared to sun or cabinet drier dried product. The additional expenditure spent on gas in CRIDA drier is compensated by reduced labour cost and higher price for the better quality product. Alternate energy sources like biogas and biomass can be used as fuel in the CRIDA drier.

Development and quality evaluation of aonla mouth freshner.

Nutritive and palatable mouth freshners were prepared from dehydrated aonla (Emblica officinalis Gaertn) pulp of 'Desi' and 'Banarsi' cultivars by mixing carboxy methyl cellulose, gums, arecanut, cardamom, sugar and milk powder at different proportions as a substitute for pan masala, tobacco and gutka. Mouth fresheners developed were packed in high density polyethylene pouches (HDPE, 100 gauge), stored at ambient conditions (8-20 °C, 60%RH) and analysed for physico-chemical and sensory quality attributes at different storage intervals. During storage for 6 months, ascorbic acid and overall acceptability of mouth freshener decreased (p ≤ 0.05) and moisture content increased. The equivalent relative humidity of mouth freshener was 49% and 53% in 'Desi' and 'Banarsi' cultivars, respectively. Despite the changes observed in various physico- chemical and sensory attributes, the overall sensory quality attributes of mouth freshners remained acceptable.

RAPD based genetic variability among cultivated varieties of Aonla (Indian Gooseberry, Phyllanthus emblica L.).

Aonla, the Indian Gooseberry (Phyllanthus emblica) is widely grown in India due to its neutraceutical properties. Investigations on the use of RAPD markers enabled us to estimate genetic variability among commercially cultivated varieties. This study also enabled us to distinguish these varieties using a set of four decamer primers, which was otherwise difficult by using morphological markers. Cluster analysis revealed three different groups of varieties directly associated to their place of origin. RAPD markers were also able to differentiate varieties of same origin or even selection from same parents. This information can be used for identification of varieties and further crop improvement programme.