Time course evaluation of biochemical contents and biocatalytic activities of jiaosu from fruit wastes during one-year natural fermentation

Rhupinee, Punniamoorthy (2025) Time course evaluation of biochemical contents and biocatalytic activities of jiaosu from fruit wastes during one-year natural fermentation. Master dissertation/thesis, UTAR.

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Abstract

Jiaosu is a multifunctional organic solution derived from fermentation of a mixture of fruit or vegetable wastes, sugar and water for a typical period of three months. The production of jiaosu is an inexpensive approach to reduce food waste. However, the significance of a fermentation period of three months or longer remains to be ascertained. Therefore, the present study evaluated the changes in pH, concentrations of proteins, phenolics, carbohydrates, alcohols, and organic acids (oxalic, tartaric, malic, lactic, acetic, citric, and succinic) as well as amylase, protease, and lipase activities of different groups of fruit peel jiaosu throughout one year of natural fermentation. Three jiaosu groups, each with different types of fruit peels were prepared: orange-papaya-watermelon (OPW), grapefruit-mango-pineapple (GMP), and durian-jackfruit-passion fruit (DJP). A total of 19 jiaosu samples (day 0, 7, 14, 21, 28, 42, 56, 70, 84, 90, 120, 150, 180, 210, 240, 270, 300, 330, and 360) were analysed for each group. Using day 90 as a reference point for all three jiaosu groups, fermentation caused significant increases (p < 0.05) in phenolics (from 0.17-0.84 to 2.25-5.66 mg GAE/mL), alcohols (from 0% to 4.47-10.47%), malic acid (from 67.36-159.63 to 206.32-403.49 μg/mL), lactic acid (from 67.30-133.41 to 493.19-8353.75 μg/mL), acetic acid (from 61.97-171.84 to 3591.78-6265.55 μg/mL), citric acid (from 32.49-52.67 to 443.73-981.95 μg/mL), and succinic acid (from 433.61-584.63 to 1258.85-2969.13 μg/mL) whereas significant decreases (p < 0.05) were observed in pH (from 4.29-5.19 to 3.11-3.24), carbohydrates (from 52.58-105.31 to 1.48-9.49 mg/mL), and amylase activity (from 237.31-2507.97 to 60.35-118.38 μmol/min/μg protein) compared to before fermentation (day 0). Throughout the one-year fermentation period, the pH, the concentrations of proteins, phenolics, carbohydrates, alcohols, and lactic acid, the amylase, protease, and lipase activities were significantly different (p < 0.05) between all three groups of jiaosu. Notably, GMP showed the highest total protein and phenolic concentrations and the lowest protease activity (p < 0.05) while DJP exhibited the highest lipase activity and lactic acid concentration, and the lowest total alcohol concentration (p < 0.05). The results indicated that the biochemical content and enzyme activities of jiaosu could be influenced by fermentation duration and the types of fruit peels used for fermentation.

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