Insights into the effect mechanism of freeze-thaw cycles on starch gel structure and quality characteristics of frozen extruded whole buckwheat noodles.

ABSTRACT

The effects of freeze-thaw cycles (FTC) on starch gel structure and quality characteristics of frozen extruded whole buckwheat noodles (FEWBN) were studied. The repeated FTC treatments induced the retrogradation of amylose which increased the compactness, crystallinity, hardness, and cooking time of FEWBN. However, with the increasing number of freeze-thaw cycles, the larger volume of ice crystals formed in the noodles destroyed the starch gel network structure to a certain extent, and led to the dehydration and syneresis of the noodles, and the quality deterioration. However, moderate amylose retrogradation occurred during the FTC treatment was found to be beneficial for the quality of FEWBN. After one time of FTC treatment, the cooking loss of 3.53 % was even lower compared with that without FTC treatment (4.61 %). After seven times of FTC treatment, the cooking loss of FEWBN was 6.53 %, and the breaking rate was still 0, indicating that FEWBN could resist the damage caused by temperature fluctuations on the internal structure of frozen food to a certain extent, and maintain good quality. This study establishes a fundamental basis for the development of buckwheat noodles with good freeze-thaw stability and high cooking quality.