ماندگاري برش هاي خربزه پوشش داده شده با پروتيين آب پنير در شرايط سرد

Shelf-life stability of fresh-cuts melon coated with whey protein stored at low temperatures

Background and Objectives: Edible coatings prepared from whey protein concentrate and glycerol were evaluated for their ability to maintain quality and improve shelf-life of fresh-cut melon stored at 5°C. Materials and Methods: Coatings were prepared containing different quantities (5, 7.5 and 10 gr) of whey protein concentrate and used to coat fresh-cut melon slices. Uncoated fresh-cuts melon slices were served as control. For comparative purposes, a sample of melon slices was treated with a 1% calcium chloride (CaCl2) solution usually used in producing fruit slices. Shelf-life of all the samples was assessed based on weight loss, color changes (1*, a*, b* and a/b*), flesh firmness, titratable acidity (TA), total soluble solids (TSS), and sensory properties. Results: As compared to the control and CaCl2 samples, the whey protein concentrate coating brought about a decrease in weight loss of the fresh-cut melon slices. No statistically significant differences in TSS and TA were observed between the coated sample and controls after 4 weeks storage at 4±1°C, but the coated and CaC^-treated melon slices were significantly (p<0.05) firmer than the control slices. The difference in firmness between the coated and CaC^-treated melon slices was not significant. The data also showed that, based on the L*a*b* color measuring system, the coated fresh-cuts of melon showed higher L* and a*, and lower b* and a/b*, values compared to uncoated control slices. With regard to sensory properties of the melon samples, the panelists rated whey protein-coated fresh-cut fruit higher than the uncoated samples, although samples with different contents of the coating were not significantly different at the end of the storage period (P>0.05). The results also showed that the coated fruit samples received the highest score with regard to flavor, gloss, and overall acceptability. In addition, the whey protein-coated samples showed a significant decrease in gloss compared to control and CaC^-treated samples. Increasing the level of whey protein in the coated samples led to increases in elasticity modulus, tensile strength, and elongation. Conclusion: Edible whey protein-based coating can be used as a new, effective method in cold storage of fresh-cut fruits.