Effect of Addition of Cryoprotectants on Frozen/Thawed Mashed Potatoes Flavor by Sensory Evaluation
Frozen purees made from vegetables are a relatively new kind of high-quality and functional product, offering extended shelf life, better manufacturing, distribution flexibility and food safety. Mashed potatoes may be suitable for freezing as a ready-meal component or as a single product. However, freezing and thawing adversely affect the cells and cell components of mashed vegetables causing textural changes and more importantly degradation of sensory properties. The quality of mashed potatoes is influenced by various factors but more importantly by the sensory characteristics which are significant for consumer selection and acceptability. Recent studies have demonstrated that incorporation of cryoprotectant blends, such as non-starchy hydrocolloids, to starch based products like mashed potatoes is effective for ameliorating the detrimental effects of freezing and thawing. Hydrocolloids offer a protection to cells and cell components against the deleterious effects of thawing in particular, such as starch retrogradation, syneresis etc, since they interact with water and have been reported to slow down the rate of ice crystal growth and alter crystal shapes. Moreover, studies have proved the dependency between the structure of starch and the flavor of thawed potato products, affecting also the taste, texture, color and odor of these products. Recently, is attempted to incorporate prebiotic agents and dietary fiber as they enhance flavor and products become more appealing to consumers pursuing a healthy diet. The purpose of this research was to investigate the effect of addition of cryoprotectants on frozen/thawed mashed potatoes flavor and texture properties examined by sensory evaluation. The frozen/thawed samples were stored for two months and the change of flavor and texture during storage was monitored. The cryoprotectant materials that were investigated, were polysaccharides (κ-carrageenan, xanthan gum, chitosan), oligosaccharides (inulin), disaccharides (trehalose), dietary fiber (oat, potato fiber) and hydrocolloids (HPMC) and were incorporated in samples individually or as blends. The samples of frozen/thawed mashed potatoes were subjected to a quantitative descriptive profile analysis. Sensory evaluation was conducted by an eight-member panel with specific training on completing the tests. The assessors scored separately 5 sensory characteristics of texture, such as gummy, cohesive, flavor and odor using a 10-point scale. Also, a pleasure scoring for the Overall Acceptance (OA) of the samples was carried out based on all sensory attributes using also a 10-point scale. Finally, statistical analysis of sensory data was carried out for further processing of results and conclusions.