Suppression of retrogradation of gelatinized rice starch by anti-listerial grass carp protein hydrolysate

Retrogradation of gelatinized starch is a well-known phenomenon causing quality deterioration of starch-containing foods during storage. The objective of this work was to study physical phenomena underlying the reduced retrogradation of gelatinized rice starch (GRS) by anti-listerial grass carp protein hydrolysate (AGCPH) during short-term and long-term storage. The AGCPH was produced from grass carp protein using neutrase to a hydrolysis degree of 19% that was previously shown to have strong anti-listerial properties. Rheological results showed that a greater amount of AGCPH significantly reduced the storage modulus to a greater extent during heating from 25 to 95 degrees C at 5 degrees C/min, cooling from 95 to 25 degrees C at 5 degrees C/min, and the subsequent holding at 25 degrees C for 180 min, indicating the short-term suppression of GRS retrogradation by AGCPH. During the 14-day storage at 4 degrees C, the addition of AGCPH significantly reduced the hardness of pastes from 878.9 to 350.6 g, and the percentage of retrogradation was decreased from 82.2% to 21.7% according to differential scanning calorimetry, while the recrystallization of GRS based on X-ray diffraction spectroscopy was reduced from 13.4% to 6.9% when the GRS: AGCPH mass ratio decreased from 100: 0 to 88:12. In addition, confocal laser scanning microscopy and atomic force microscopy showed that AGCPH bound with GRS starch molecules to block the formation of hydrogen bonds to impact intra-and inter-particle interactions and inhibit the recrystallization of GRS. The findings suggest that AGCPH may be used to significantly inhibit the short-term and long-term retrogradation of GRS to improve the safety and quality of refrigerated paste products. (C) 2017 Elsevier Ltd. All rights reserved.