Retrogradation‐induced physicochemical changes in pre‐cooked rice noodles stored at different temperatures: a viewpoint from water dynamics and structure

Abstract

BackgroundThere has been significant interest in pre‐cooked noodles that have a long shelf life and are convenient to cook. However, the thermal processes during preparation as well as their high moisture content can lead to significant quality deterioration during storage. Nevertheless, a comprehensive evaluation of these quality losses has not yet been conducted.ResultsThe effects of different storage temperatures (25oC, 4oC, and ‐20oC) on the retrogradation‐related physicochemical changes of pre‐cooked rice noodles were elucidated mainly from the water dynamics and structural points of view. The thermal analysis demonstrated that amylopectin recrystallization distinctly took place in the noodles stored at refrigerated temperature, followed by room temperature. The refrigerated storage accelerated the starch retrogradation that caused the water molecules to become entrapped within the crystalline structure, by lowering the water hydration properties and weighted T2 relaxation times of the pre‐cooked noodles. These water mobility patterns were correlated with the textural changes of the noodles (higher hardness and Rmax/extensibility). Furthermore, the higher structural density and thickness derived from starch retrogradation were observed in the tomographic and microscopic images of the refrigerated noodles. The principal component analysis demonstrated that various physicochemical changes of the pre‐cooked noodles during storage showed high correlations with the degree of starch retrogradation (r>0.83).ConclusionThe physicochemical features of the precooked noodles stored under the refrigerated condidtion were distinctly involved in the molecular dynamics of water that showed a notable water mobility reduction derived from the starch retrogradation, which consequently contributed to their thermal, tomographical, and textural changes.This article is protected by copyright. All rights reserved.