Chinese steamed bread: Packaging conditions and starch retrogradation

Abstract

Background and objectives: The starch retrogradation of Chinese steamed bread (CSB) under different packaging conditions (sealed package [SP], vacuum package [VP], and thermal-vacuum package [T-VP]) was compared in the present study. Parameters including moisture content, moisture migration, starch granule structure, and starch retrogradation were monitored by NMR, SEM, XRD, and FT-IR. Findings: During storage, T-VP steamed bread kept higher water content and had longer shelf life compared to SP and VP. T-VP hindered the interactions among water molecules, gluten, and starch, thus relatively increasing the mobility of water molecules represented by T 23 in NMR tests compared to SP.T-VP decreased the speed of CSB starch granules getting narrowing in SEM, maintaining a good taste of steamed bread. Results from FT-IR and XRD suggested a lower retrogradation rate of CSB starch with T-VP as compared to SP and VP, and the retrogradation of CSB starch was affected by free water during storage. Conclusions: Thermal-vacuum package could delay the speed of water desorption, blocked the interaction among water molecules, gluten and starch and slowed the adhesion between starch granule, thus retard starch retrogradation of CSB. Significance and novelty: Thermal-vacuum package technology as an anti-retrogradation packaging system for CSB preservation could extend the shelf life of CSB for at least 84 days at room temperature. K E Y W O R D S

Effect of wheat gluten addition on the quality of thermal‐vacuum packaged Chinese steamed bread

“…In addition, the change of band intensity arose from the transformation in starch conformation, such as long‐range ordering and crystallinity, and the band narrowing effect was caused by the ordered state of the starch structure and a smaller distribution of bond energies in the process of retrogradation. It was also observed that the intensity of the starch region (1,300–800 cm −1 ) absorption band decreased with the wheat gluten ratio increase, which indicated that the wheat gluten retarded the retrogradation of starch (Liu, Wang, Ma, et al., 2019).…”

“…The method of making CSB was referred by Liu, Wang, Ma, et al. (2019). The dough was prepared by raw material mixing for 10 min using a HWH‐25 dough mixer (Xinxiang Ltd. Co.).…”

“…The determination was carried out according to the method of Liu, Wang, Ma, et al. (2019). The samples were compressed to 50% of their initial thickness by the probe of P/36R; moreover, the first, middle, and final test speed were 3, 1, and 5 mm/s, respectively.…”