Change of chemical and biochemical indicators of Phuc Trach pomelo in the preservation process with chitosan-based coating with tannin and vinegar

Abstract

The objective of this study was to determine the change in physicochemical and biochemical parameters of Phuc Trach pomelo during preservation by coating. From there, it forms the basis for building a preservation process. Preservative coating preparations are formed by mixing ingredients according to the ratio: 1.92% chitosan, 0.24% tannin, 1.92% vinegar, and 95.92% water. One kg of this preparation will be enough to cover about 19 kg of pomelo. Set up four experimental formulas to preserve Phuc Trach pomelo: CT1: preserved in the natural environment, no preservative coating is used, the content of coating-forming preparations is 0%; CT2, CT3, CT4 used coatingforming preparations with the content of 1.0%, 1.5% and 2.0%, respectively. The results showed that Phuc Trach pomelo preserved in formula CT3 with the composition of 1.5% was effective in limiting the change of physico-chemical and biochemical indicators more effectively than other experimental formulas. After 7 weeks of storage, the colour changed from 0.96 to 8.16, hardness changed from 15.16 to 10.23 (kg/cm2 ); respiratory intensity from 35.68 to 18.95 (mL CO2/kg.h); soluble solids content from 10.04 to 11.46oBx; total sugar content from 8.99 to 5.06%; vitamin C content from 0.84 to 0.42mg/g; total protein content from 0.79 to 0.38%; total organic acid content from 0.62 to 0.17%. Meanwhile, Phuc Trach pomelos preserved in other recipes until the 5th and 6th week were completely rotten. Therefore, the formula CT3 was selected with a preservative composition of 1.5% to develop the process of preserving Phuc Trach pomelo.