Kinetic modeling of microbial degradation and antioxidant reduction in lychee juice subjected to UV radiation and shelf life during cold storage

Abstract

Lychee juice is highly perishable food and typical thermal processing may cause alteration in product quality. This study was conducted to investigate the kinetic model of microbial degradation (total plate count and yeast and mold count) and antioxidant properties reduction (total phenolic compound, total flavonoid content and antioxidant activity by DPPH and FRAP assays) of lychee juice subjected to various ultraviolet UV radiation doses (0–74.88 J/cm2). Physical and chemical properties of lychee juice treated with UV treatment and shelf life during cold storage at 4 °C compared to pasteurized sample (85 °C 15 s) were also determined. Kinetics of microbial degradation and antioxidant properties reduction were best-fitted by first-order kinetic model with coefficient of determination (R2) values and rate constants (k) ranging from 0.9759 to 0.9935 and 0.0008–0.1060, respectively. No significant difference was observed in pH, °Brix, %titratable acidity, total flavonoid content and antioxidant activity by DPPH assay. Based on microbial shelf life, UV radiation could extent the shelf life of lychee juice approximately 7 days compared to control sample during storage at 4 °C. The data of present research contribute to support the application of UV radiation treatment as a promising technique to preserve quality, prevent microbial spoilage and improve shelf life of lychee juice during cold storage.