Effects of different thawing methods on microstructure and texture of raspberries (cv. Heritage)
The effects of different thawing methods on changes in the microstructure and texture of fresh raspberry (cv. Heritage) samples were investigated in this study. The freezing point of raspberry samples ranges from 0 to -0.2°C, which differs notably from other fruits. The firmness of all thawed raspberry samples decreased in comparison to those of fresh raspberry samples. The suitability of thawing conditions is dependent on the temperature and duration of thawing. Thawing at 4°C for 3h led to significantly higher (p<0.05) firmness than other samples. Thawing at 20°C for 1h was a favorable technique for retaining the original tissue structure of raspberries. These results suggest future researchers and developers would optimize fruit thawing processes at lower temperature for a longer duration.
Raspberries, consumed in yogurts, jams, jellies, and concentrates, are among the most popular berry fruits in the world (1). Raspberries are highly perishable and commonly frozen before use (2). The freezing and thawing processes would result in loss of textural quality due to the formation of ice crystals which initiate rupturing irreversible structural damage of cellular membranes, cell walls, middle lamellae, and protoplast (3, 4). Many previous studies have been conducted on the effect of freezing on berry quality. Different freezing techniques were investigated to reduce damaging the texture of the fruit (5-10). However, research on the specific effects of thawing on the texture and structure of raspberries subjected to different freezing methods is limited. The aim of this study was to explore the effects of different thawing methods on microstructure and texture of raspberries to determine which condition was the most favorable. We hope to minimize the detrimental effects of freezing and thawing by determining the optimal thawing process or method.
MATERIALS AND METHODS