Performance and mechanism of an innovative humidity-controlled hot-air drying method for concentrated starch gels: A case of sweet potato starch noodles. (15th December 2018)

• Record Type: Journal Article
• Authors: Xiang, Zhuoya; Ye, Fayin; Zhou, Yun; Wang, Lei; Zhao, Guohua
• Is Part Of: Food chemistry. Volume 269(2018)
• Page Start: 193
• Page End: 201
• Publication Date: 2018-12-15
• Subjects: Starch gel -- Sweet potato -- Retrogradation -- Drying -- Humidity-controlled -- Starch noodles -- Rehydration -- Textural analysis; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2018.06.153
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Effects of RH control in hot air drying on starch noodles are investigated. RH regulation at early stage of hot air drying favors the quality of dried noodles. High RH hot air drying confers dried gel with high shrinkage and porosity thereof. The surface smoothness and shape of dried gel highly depended on RH of drying air. RH control affects dried starch gels intrinsically via changing starch retrogradation. Abstract: The effects of humidity control on dried starch gels were investigated using starch noodles as a model. A two-stage innovative hot-air-drying regime was developed with the first stage humidity-controlled (70 °C, 60% RH) and the second at high temperature (100 °C). The proposed drying method is comparable to natural-air-drying in product quality and to conventional hot-air-drying (70 °C) in production efficiency. The operating humidity of the first stage predominated the swelling index and rehydration ratio of dry noodles as well as the hardness and chewiness of cooked noodles. The results from XRD, DSC, SEM, digital microscopy and low field TD 1 H NMR evidenced that these outcomes were largely ascribed to the higher shrinkage, lower porosity, smoother surface, lesser shape deformation and higher starch retrogradation resulting from increased humidity. The results reported herein are valuable for regulating the physicochemical properties of dried starch gels and glimpsing the underlying mechanisms of related operations.