Reduction method of sulfur dioxide residues during ‘Kyoho’ grapes storage with modified edible chitosan coatings treatment

• 0.5% CMCS+2.0% NaHCO 3 treatment showed the best effect on reducing sulfite residue. • This coating method did not influence antifungal activity of SO 2 preservative . • Physiological damages were significantly alleviated. • Preservation quality was relatively improved. Sulfur dioxide (SO 2 ) has been presently applied as main preservative in table grapes storage. However, excessive accumulation of SO 2 could cause substantial adverse effects to berry quality, with even damage to consumer health. Chitosan (CS) has been used to reduce sulfite residue in some food, however there is still very little study about CS on reducing grape berry residue sulfites. This study explored reducing sulfite residue in grape effectively using a new coating method without influencing SO 2 preservation effect. First, the effects on residual sulfite in berry coated chitosan with multiple concentrations, molecular weights and modification types were investigated, indicating 0.5% carboxymethyl chitosan (CMCS) with the best effect on reducing sulfite residues in berry pulp and peel. Further, 0.5% CMCS+2.0% NaHCO 3 treatment declined 43.76% sulfite residue in pulp than SO 2 alone treatment. The sulfite residue in pulp underwent this treatment was both less than 20 mg kg -1 when stored at 25 °C and 0 °C. Finally, this treatment didn’t influence SO 2 antifungal activity, overtly alleviated berries physiological damages, as well improved quality. Thus, 0.5% CMCS+2.0% NaHCO 3 treatment was proved as cost-effective method to reduce sulfite residue and comparatively improve quality during table grapes storage, without descending SO 2 preservation effect.