Abstract: In order to reduce the incidence of black spots and decay as well as the loss of nutrients and to prolong the shelf life of mango fruit stored at room temperature, a tannic acid (TA)-bleached shellac composite preservative was prepared. The concentrations of TA and bleached shellac were used as the variables and the mass loss percentage and the incidence of black spots in mango fruit were used as the response values to optimize the formulation of the composite preservative using response surface methodology based on central composite design. Meanwhile, the physical and chemical indexes of the optimized formulation were tested. The results showed that the composite preservative could obviously prolong the shelf life of mango fruit at room temperature. The optimal proportions (m/m) of the ingredients were 7.3% bleached shellac, 0.3% TA. The mass loss percentage and the incidence of black spots in mango fruit treated with the optimized preservative were 24.38% and 29.91% after 18 days of storage, respectively. Compared with the blank control group, the preservative significantly reduced the loss of nutrients such as titration acid, soluble sugar, total soluble solids and ascorbic acid in mangoes, delayed the decaying process and prolonged shelf life by at least 8 days. The sensory, physicochemical indexes of the preservative, including viscosity, ignition residue, total arsenic and lead content, were all in line with the requirements of the national standard, which indicates that the preservative is green, safe and non-toxic.

Key words: mango, quality preservation, shellac, tannic acid, response surface optimization