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Effects of different thawing methods on microstructure and texture of raspberries (cv. Heritage)

corresponding

HONGLI SHANG1,2, LI LI1, XIAOJIE HONG2, JIANXIN SONG1, XIANJUN MENG1*

*Corresponding author

1. Food science college, Shenyang Agricultural University, Shenyang 110000, China
2. College of Food Science and Engineering, Liaoning Medical University, Jinzhou 121000, China

Abstract

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.


INTRODUCTION

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 metho