Stability of selected quality attributes of pink guava juice during storage at elevated temperatures
2016
Aishah B. | Hannah K. | Zati Alyani O.
Quality degradation is normally judge by monitoring independently the loss of a certain quality attribute during storage. However, the rate of degradation for each of the quality attributespresent in a food product is not the same. This study focus on deterioration of vitamin C, lycopene, total phenolics and antioxidant activity of ready-to-drink pink guava juice (PGJ) during storage at elevated temperatures. Kinetic order, rate constant (k), activation energy(Ea) and temperature coefficient (Q10) of the degradation were derived by applying Arrheniusequation. The results obtained showed that freshly made PGJ contain 39.79±2.18 mg/100 mL of vitamin C, 3.17±0.27 mg/L of lycopene, 28.08±4.11 mgGAE/100 mL of total phenolic content (TPC) and 13.20±1.91 mMTE/100 mL of ferric reducing antioxidant power (FRAP).All quality attributes measured in this study showed zero-order kinetic reaction. The resultsalso showed that FRAP has the highest Ea of 49.52 KJ/mol and Q10 of 1.80, followed by vitamin C (Ea=41.49 KJ/mol; Q10=1.64), lycopene (Ea=31.75 KJ/mol; Q10=1.46), and lastly TPC (Ea=14.11 KJ/mol; Q10=1.18). The predicted total depletion of each quality attributeat refrigerated storage (5oC) were 266 days for antioxidant activity, 158 days for vitamin Cand lycopene, and 63 days for total phenolics. This study provide useful information on the degradation rate and availability of health beneficial and bioactive compounds present in fruitjuice beverage during storage.
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