Role of L-cysteine and green tea extracts for minimizing the non-enzymatic browning in guava nectar.

摘要

The non-enzymatic browning is considered as one of the main problems in guava nectar glass packaged. So, this work was aimed to minimizing the non-enzymatic browning by using green tea extract and L-cysteine. Physico-chemical analysis of guava juice indicated that the juice yield and total soluble solids were 75.8% and 9.7% respectively while it contained 95.5 mg/100 g ascorbic acid. The results illustrated that the changes in color was very low during storage at room temperature for 6 months by using these inhibitors. The statistical analysis of sensory evaluation of guava nectar bottled in glass treated with green tea extract and L-cystiene then stored at room temperature, were extremely analogous to that of cooled samples without the addition of antibrowning inhibitors in their constituents. On the other hand the results revealed that the use of 400 ppm of L-cysteine or 400 ppm of green tea extract minimized non-enzymatic browning without any undesirable effect on the sensory properties. Sodium metabisulfite, 50 ppm in addition to 200 ppm of green tea extract, gave high quality and acceptable guava nectar. Therefore, the addition of 400 ppm of L-cysteine or 400 ppm of green tea extracts caused to reduce non-enzymatic browning in glass bottled guava nectar.