Comparative study of conventional and novel combined modes of microwave- and infrared-assisted thawing on quality of frozen green pepper, carrot and cantaloupe
Bing Chen, Min Zhang, Yuchuan Wang, Sakamon Devahastin, Dongxing Yu
Abstract
Combined microwave- and infrared-assisted thawing is proposed as novel means to improve thawing efficiency of selected materials, namely, green pepper, carrot and cantaloupe; ambient-temperature thawing was also conducted and compared. Quality of thawed products was evaluated in terms of thawing loss, water distribution, color, hardness, ascorbic acid content, flavor, cell damage and microstructure. Compared with ambient-temperature thawing, thawing time of the combined treatment could be shortened by 65–75%, while thawing loss decreased by 10–40%. Interestingly, order at which the two field-assisted thawing was applied exerted significant effect on both thawing time and quality of thawed products. Applying infrared heating prior to microwave heating was noted to be superior. Losses of ascorbic acid could, for example, be as low as 0.4%. Relative conductivity, which indirectly indicates cell damage, could be reduced by 16–77%; acidity and astringency and umami of thawed products were noted to decrease and increase, respectively, with such strategy.