Protein-based coatings on peanut to minimise oil migration

Soy protein isolate (SPI) or calcium caseinate (CC)-based coatings were applied on peanuts as a barrier of oil migration, and their efficiency was evaluated. These coatings induced a decrease of oil migration as compared to the uncoated peanuts. Subsequently, three polysaccharides were individually added to the coating solution to prevent oil migration further. The incorporation of carboxymethylcellulose (CMC) with SPI and CC coating solutions significantly (p ⩽ 0.05) decreased the migration of oil as compared to the coatings without CMC. The addition of pectin seemed unfavourable because it enhanced the migration of oil. Starch in SPI-based coating solution helped to decrease the oil migration, but it did not affect the migration level in samples treated with CC solution. The results from size-exclusion chromatography showed strong cross-links by glutaraldehyde and transglutaminase treatments in SPI and CC-based coating solutions. A strong cross-linking in protein-based coating correlated closely with a reduction in oil migration. For both proteins, the cross-linking by transglutaminase was most efficient for improving the effectiveness of coating. This study demonstrated that our protein-based coatings can be effectively implemented to food industry for better quality of peanut products.