LAUSR

BACKGROUND Red pitaya peel (RPP) is a good source of polysaccharides acting as a biodegradable material, betacyanins in it possess antioxidant and pH-sensitive properties. However, RPP is commonly discarded during fruit processing. It's full of challenges to evaluate the freshness of protein-rich products rapidly and accurately. This study was aimed to develop real-time intelligent film using RPP to evaluate pork freshness. RESULTS Real-time intelligent films were developed with film-forming substrates (FFS) composed by 60-100% (w/w) RPP and 0-4% (v/w) glycerol in pH 4.3~8.0. Rheology tests revealed that the FFS exhibited a shear-thinning behavior. FT-IR analysis showed that molecules in the RPP interacted with glycerol and formed hydrogen bonds. It showed the film developed with FFS of 80% RPP and 2% (v/w) glycerol had strong molecular interaction, dense structure, and optimal tensile strength and elongation at break. The film with pH shifting to 7.0 had higher sensitivity to ammonia than that was prepared at original pH = 4.3, thereby this film was used to monitor freshness of pork. A visible change in the color of film was observed during the spoiling process of pork, which was correlative with the accumulated total volatile base nitrogen. CONCLUSION Base on the sensitivity to ammonia and real-time evaluation of pork freshness, the film made of 80% (w/w) RPP and 2% (v/w) glycerol at pH 7.0 was recommended to be used in monitoring freshness of protein-rich food. Our findings are of great significance for ensuring meat quality and safety as well as reducing food waste. This article is protected by copyright. All rights reserved.