Abstract:

Development of natural and safe browning inhibitors is a hot spot for the prevention of fruit juice browning.
In this study, loquat juice from the cultivar “Ninghaibai” was used to study the effects of different concentrations of
crude schizophyllan combined with four common browning inhibitors (oxalic acid, citric acid, VC, and L-cysteine) on
prevention of loquat juice from browning. It was indicated that the order of the efficacy of five browning inhibitors was as
follows: L-cysteine > oxalic acid > VC > citric acid > schizophyllan. The percent inhibition of browning by schizophyllan
at a concentration of 0.8% was over 80%. Based on fruit juice flavor, we chose the inhibitor combination consisting of
schizophyllan, ascorbic acid and L-cysteine. The optimum inhibitor combination, i.e. 1% schizophyllan, 0.025% ascorbic
acid and 0.004% L-cysteine, was obtained using response surface methodology. The results of verification showed that
the percent inhibition of juice browning by the optimized combination was 98.04%, approaching to the predicted value of
99.22%, suggesting that the response surface model was reliable. The contents of total soluble solids (TSS), ascorbic acid
and total phenol in loquat juice were increased after treatment with the inhibitor combination. These results showed that
schizophyllan can be used in combination with other inhibitors to prevent loquat juice browning.

Key words: loquat juice, browning, schizophyllan, optimization