In the present study, the effects of heat-moisture treatment (HMT) on the structural properties, physicochemical properties and in vitro digestibility of sweet potato flour were investigated. Moisture mass fractions of samples were set as 20%, 25%, 30% or 35%, and treated at 110 °C for 4 h. Gelatinization characteristics, short-range order, double helix structure, crystallinity and digestive characteristics were studied by test of pasting and thermal, analysis of X-ray diffraction spectra, infrared spectra and in vitro digestion test. The results showed that the structural characteristics of the sweet potato flour with different moisture concentrations were quite different. The viscosity, breakdown value and setback value of HMT-sweet potato flour were all lower than those of the original flour. The content of rapidly digestible starch (RDS) decreased, while the contents of slowly digestible starch (SDS) and resistant starch (RS) increased after HMT. The results showed that HMT-25 had good cold and heat stability, low pasting viscosity and high contents of SDS and RS.
The lactic acid bacteria (LAB) with excellent fermented performance were screened for Lentinus edodes fermentation by measuring the growth status and acid producing capacity of different LAB in L. edodes, and the optimal mixed ratio of LAB was selected for the L. edodes fermentation through the mixed fermented test. Factors affecting the quality of fermented L. edodes were optimized by single factor experiment and response surface experiment. The results showed that when the mixed ratio of LAB was Lactobacillus delbrueckii subsp. bulgaricus: Lactiplantibacillus plantarum: Lacticaseibacillus rhamnous = 3:1:2, fermented L. edodes had the best fermented quality. The optimized process parameters of mixed LAB fermented L. edodes were as follows: fermentation temperature of 37 °C, salt content of 1%, and inoculation amount of 2.7%. Under this process, the total acid and sensory score of fermented L. edodes were 0.88 g/100 g and 81.7 points, respectively. Compared with the unfermented L. edodes, the contents of acids and ketones in the fermented L. edodes increased by 2.16% and 17.8%, while the contents of alcohols, aldehydes and phenols were relatively reduced by 3.66%, 7.42%, and 3.87%, respectively. This study provides a theoretical basis for the development of LAB fermented food of L. edodes.
Summary
In this paper, the effects of fatty acid‐blending heat‐moisture treatment (FA‐HMT) on the physicochemical and in vitro digestion properties of sweet potato flour (SPF) were studied based on the study on the physical modification of SPF by HMT. The results showed that the addition of linoleic acid (LOA)/Palmitic acid (PA) damaged the double helix structure of SPF, and reduced the long‐range order, relative crystallinity, anti‐aging, anti‐shearing properties and slow digestible starch (SDS) content of SPF. However, the FA‐HMT promoted the increase of RS5 (starch‐lipid complex) content in SPF, which had a certain positive effect on improving the intestinal environment. The results showed that when the addition ratio of LOA was 2%, the SDS content of SPF decreased slightly, and the SPF had better anti‐aging, anti‐shearing properties and higher RS5 content.
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