Influence of quince seed mucilage-alginate composite hydrogel coatings on quality of fresh walnut kernels during...

The presence of high unsaturated fat content and polyphenols results in the short storage life of fresh walnut kernels. For prolonging their shelf life, edible coatings incorporated with antimicrobial compounds can be used as a tool. Quince seed mucilage was identified as a novel green biomaterial to be explored as a coating substance. Quince seed mucilage and sodium alginate were mixed in five different proportions of 100:0 (QAH₁), 80:20 (QAH₂), 60:40 (QAH₃), 40:60 (QAH₄), and 20:80 (QAH₅) and the resultant composite hydrogels were studied for different physical properties. These composite hydrogels incorporated with vanillin were coated on fresh walnut kernels while uncoated samples served as control. Composite hydrogel coatings with a higher proportion of QSM retained a higher whiteness index, lightness (L*), DPPH radical scavenging capacity, total phenolic content, and overall acceptability values in walnut kernels during the entire storage period of 35 days. QAH₁ showed the lowest weight loss percentage, lipid oxidation, and yeast and mold counts while the control sample showed the highest (P < 0.05) values. The results concluded that quince-based composite hydrogel coatings were effective in retention of quality and prevention of degradation of fresh walnut kernels during the storage.