Abstract
ABSTRACT The gel properties and structural changes of sweet potato starch induced by heat-moisture treatment (HMT) were investigated, and its vermicelli textural properties were revealed. HMT increased the relative crystallinity, and the crystallinity reduced with increasing moisture content, which was consistent with the results of DSC. RVA results revealed that the HMT starches showed an increased setback viscosity and a reduced breakdown viscosity, indicating that the HMT starches gel lead a stronger retrogradation tendency. Rheometer results indicated that the HMT starches had a stronger elasticity behavior. The content of amylose of starch and the possible amylose fine molecular change during HMT at different water content were hypothesized, and this caused the gel properties of starch. Consequently, the HMT starch vermicelli exhibited higher hardness, springiness, and chewiness. These mechanistic relations among starch structure, gel properties, and vermicelli quality during HMT will provide useful information for the starch vermicelli industry.
Highlights
Sweet potato is the seventh most important food crop and is recognized as the primary starchproducing crop worldwide
All the modified starch samples exhibited higher relative crystallinity (15.52%, 15.12%, 14.86% and 14.73% for moisture content 22%, 26%, 30%,34%,respectively) than native starch sample (14.58%), which might be due to further enhanced associations between starch chains, and the structure rearrangement of the disrupted double helices that led to an increase in crystal perfection or the new crystallite formation of heat-moisture treatment (HMT).[12]
X-ray results displayed that the crystallinity of the HMT starches increased compared with that of native starch, the crystallinity reduced with increasing moisture content
Summary
Sweet potato is the seventh most important food crop and is recognized as the primary starchproducing crop worldwide. Sweet potato is rich in carbohydrates, vitamins, and fiber, and it can be eaten raw or cooked, unripe or ripe. The main product of sweet potato processing is starch, which is used in the production of traditional foods, such as vermicelli. The starch functional properties of pasting, texture, retrogradation, and rheology are critical factors in determining the end use and market demand for sweet potato starch and flour. Native starch exhibits poor properties, including low solubility, high viscosity of starch gel, and poor thermal shear, which limit its use in the industry.[1] physical and chemical modifications must be implemented to improve the functional properties and produce starch with special properties
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