Preparation of D-Phenyllactic Acid-Chitosan Biodegradable Composite Coating and Its Preservation Effect on Shine-Muscat Grape

Considering the pollution of plastic packaging and the harm of traditional food containing sulphur to the environment and human health, the development of green and edible coating materials with biodegradable power has become the focus of attention in recent years. In this study, based on a single factor test, D-Phenyl Lactic Acid-Chitosan Biodegradable Composite Coating (PACBC) was prepared by optimizing the formula of D-Phenyllactic Acid (D-PLA), Chitosan (Cs), calcium chloride, Ascorbic Acid (AA) by Response Surface Method (RSM). The preservation effect of PACBC with the optimal formula on the Shine-Muscat grape was also studied. The specific sensory indexes, flavour and nutritional quality during storage were determined. The microscopic morphology of grape peels was observed using scanning electron microscopy (SEM). The results showed that the optimal formula of PACBC was as follows: D-PLA was 0.792%, Cs was 0.484%, calcium chloride was 0.5%, and AA was 0.85%. Compared with the blank control CK1, on the sixth day of storage, PACBC prepared with the optimal formula decreased the decay rate, berry abscission ratio, browning incidence and weight loss of grapes and increased the grape firmness. The microstructure of grape peels was dense and complete. In addition, the grapes were treated with PACBC, and their appearance, colour, and freshness were good. The loss of Titratable Acid (TA), Total Soluble Solids (TSS), AA and Total Phenols (TP) in grapes was delayed. The preservation effect of PACBC with the optimal formula was better than that of the positive control (CK2) without D-PLA. In this study, compared with the traditional sulphur dioxide and plastic packaging for grape preservation, PACBC will provide a potential alternative for grape green preservation.