Enzymatic browning inhibition in minimally processed sweet potatoes analyzed by multivariate methods

Abstract

Principal component analysis (PCA) is an emerging method for data analysis in postharvest science. Minimally processed sweet potatoes (Ipomoea batatas) are of interest for its nutritional value and convenience, but enzymatic browning affects its quality. As there are many factors involved in enzymatic browning development, PCA could be used to understand browning related changes and to compare different strategies for its prevention (edible coatings and antibrowning agents).The objective of this study was to evaluate through PCA, the effect of a cassava starch edible coating added with different antibrowning agents, using chemical and sensory parameters.The experiments were performed with ´blanca´ variety cultivated in the North East of Argentina. An edible coating was prepared by partial gelation of cassava starch and three antibrowning agents (ascorbic acid, sodium metabisulphite and L-cystein) were added separately.The samples were packaged and stored at 4°C. At preset times enzymes activities of polyphenoloxidase (PPO), peroxidase (POD), phenylalanine ammonia lyase (PAL), chlorogenic acid content, antioxidant activity (AOA), color parameters and sensory attributes were evaluated. The results of the three independent experiments were evaluated by PCA using InfoStat® SoftwareThree principal components were found as necessary to explain the effects of the different treatments on enzymatic browning. The first component (PC1) explained 31% of the total variance and was primarily determined by changes in PPO and POD activities,AOA and color parameters. The second component (PC2) explained 25% of the variance being particularly related with changes in chlorogenic acid content, PAL activity and b* parameter. Finally the PC3 accounted 11% of variance and was related to changes in PAL activity and aroma. As treated samples were clustered individually and separately from control samples, the PCA technique was a very useful tool to understand how different treatments affect browning development. The ascorbic acid was the best antibrowning agent.