Factors Affecting Non-enzymatic Browning of Fermented Physalis pubescens L. Juice

Key elements involving in the non-enzymatic browning of fruit juice of Physalis pubescens L. during fermentation were analyzed to understand the underlying mechanism. A symbiotic fermentation on the juice using yeast and lactic acid bacteria simultaneously at 25℃ or 37℃ was conducted. Color changes, △E, along with the contents of vitamin C, total phenols, 5-hydroxymethylfurfural (5-HMF), reducing sugar, and amino acid nitrogen of the juice during the entire process at various temperatures were monitored for a path coefficient analysis. The results indicated that 5-HMF had the strongest effect on △E, and that its interaction with the amino acids was the main cause of the non-enzymatic browning at 25℃. At 37℃, the interaction between 5-HMF and reducing sugars appeared to be the prime source for the browning of the juice. It was, thus, concluded that 5-HMF, reducing sugars and amino acids were among the key elements that led to the color change of the fruit juice during fermentation.