Effect of Optimized Chitosan Coating Obtained by Lactic Fermentation Chemical Treatment of Shrimp Waste on the Post-Harvest Behavior of Fresh-Cut Papaya (<i>Carica papaya</i> L.)

Abstract

Chitosan is a biopolymer obtained from shrimp waste mainly by a polluting chemical method. In this work, a less polluting biological-chemical method to obtain chitosan from this waste has been optimized; this method used a successive lactic fermentation and chemical process. Additionally, in this work, the effect of chitosan coating on the post-harvest behavior of fresh-cut papaya was studied as a practical application. A rotatable central composite design (CCRD) with two variables (fermentation time and total soluble solids of the fermentation medium) was used to optimize the chitosan extraction. The optimized conditions for chitosan extraction were 108 h and 8.74 °Brix. The optimized chitosan showed a high deacetylation degree of 83%, acceptable process yield of 2.03%, a low ash content of 0.23% and a molecular weight of 107.5 kDa. In addition, optimized chitosan decreased the loss of color and acidity, as well as the growth of microorganisms; it also increased the pH of minimally processed papaya slices without a statistically significant difference with that of commercial chitosan. Based on these results, optimized chitosan could be applied to other fruits as a coating to maintain their quality characteristics and inhibit microbial growth during the storage of fresh-cut fruits.

Keywords

• chitosan coating
• lactic fermentation
• shrimp waste
• optimization
• post-harvest papaya