Effects of sea buckthorn residue protein hydrolysate on the quality of frozen pre-baked bread: Water state and gluten structures

Abstract

Fluctuations in temperature during freeze-thaw (F/T) cycles can lead to large ice crystal formation and recrystallization, resulting in the deterioration of the dough gluten network and degradation of the final product. This study aimed to explore the influence of protein hydrolysate of sea buckthorn residue (SRPH) on moisture status, gluten network structure, and prebaked bread-making properties during F/T cycles, as compared with a commercially available ice-structured protein (ISP). The results demonstrated that following six F/T cycles, the freezable moisture content of the blank control (BC), ISP, and SRPH groups exhibited increases of 12.25 %, 6.35 %, and 5.92 %, respectively. Furthermore, the free sulfhydryl groups decreased by 18.95 % and 19.32 %, the disulfide bonds increased by 16.1 % and 21.38 %, and the α-helical structure increased by 3.61 % and 3.09 % in the ISP and SPPH groups, respectively, compared to the BC group. These results indicate that the addition of SRPH to doughs can maintain the intact structure and functional properties of doughs by controlling moisture migration. This may be attributed to the fact that SRPH exhibits certain thermal hysteretic activity (0.18 °C), contains a substantial amount of hydrophilic amino acids (64.86 %), and has a high supercooling point (−11.40 °C). These results substantiate the protective effects against the freezing activity of SPPH on frozen dough during F/T cycles, thereby providing a foundation for the future creation of prebaked frozen food items.