Abstract:

The mixed culture fermentation of the fruit juice of Physalis pubescens L. with yeast and lactic acid bacteria
was carried out at 25, 30 and 37 ℃, respectively. Changes in the contents of vitamin C, total phenols, 5-hydroxymethyl
furfural (5-HMF), reducing sugar and amino acid nitrogen, associated with non-enzymatic browning occurring during the
fermentation process, were examined in order to explore the mechanism of non-enzymatic browning through path coefficient
analysis. The results indicated that the change of browning degree (BD) was closely related to 5-HMF, reducing sugar,
and amino acid nitrogen in the fruit juice of Physalis pubescens L. fermented at three temperatures. In addition, 5-HMF
had the strongest direct impact on BD, while interaction between 5-HMF and reducing sugar was the chief determinant of
non-enzymatic browning during fermentation at 25 ℃. When fermentation was done at 30 ℃, amino acid nitrogen had the
strongest direct impact on BD and the major cause of non-enzymatic browning was interaction between 5-HMF and amino
acid nitrogen. During fermentation at 37 ℃, the non-enzymatic browning of Physalis pubescens L. was mainly caused by
5-HMF as the principal determinant of BD. Therefore, Maillard reaction is the major cause of the non-enzymatic browning
of Physalis pubescens L. during the fermentation process.

Key words: Physalis pubescens L., fermentation, non-enzymatic browning, path coefficient analysis