Extraction of non-starch lipid from protease-treated wheat flour.

BACKGROUND: Lipids account for 2.0-2.5% of wheat flour by dry weight and affect properties and quality of cereal foods. A new method was developed to extract non-starch lipids from wheat flour. Wheat flour was first hydrolyzed with a protease and followed by extraction of non-starch lipids by water-saturated butanol (WSB). RESULT: Protein hydrolysis by protease followed by extraction of non-starch lipids with WSB increased yield to 1.9 ± 0.3% from 1.0 ± 0.1% with no protease treatment. The lipid profile showed a significant increase in phospholipid compounds extracted with protease hydrolysis (5.9 ± 0.8 nmol·g-1 ) versus without enzymatic treatment (2.4 ± 1.3 nmol g-1 ). CONCLUSION: Improved lipid extraction yield and phospholipid compounds following protease-assisted extraction method provided additional insight towards the understanding of protein-lipid interaction in wheat flour. The new protease-assisted extraction method may be applied to analyzing non-starch lipids in other types of wheat flours and other cereal flours. © 2021 Society of Chemical Industry.

Preparation and textural properties of white salted noodles made with hard red winter wheat flour partially replaced by different levels of cross-linked phosphorylated RS4 wheat starch.

BACKGROUND: Resistant starch (RS) has health benefits and can be used as a functional ingredient in various food products. Kansas hard red winter (HRW) wheat is conventionally used for bread making and this is attributed to its strong gluten network. To develop Asian white salted noodles with a high RS content, HRW wheat flour was partially replaced with cross-linked phosphorylated RS4 wheat starch. Vital wheat gluten or wheat protein isolate was added to compensate for textural changes due to the addition of RS. RESULTS: The maximum recommended level of RS4 starch to replace HRW wheat flour was 40%. The substitution of 10-40 parts of RS4 for flour did not change hardness in cooked noodles but it did reduce their extensibility, cohesiveness, and springiness, which was probably due to the non-swelling properties of RS4. At 40 parts of RS4 replacement, supplementation of 2-8 parts of vital wheat gluten or wheat protein isolate in the composite flour notably enhanced the hardness and extensibility of cooked noodles, whereas cohesiveness and springiness were minimally affected. Supplemental vital wheat gluten produced a thicker protein network than endogenous protein or added wheat protein isolate, giving cooked noodles greater breaking force and distance. CONCLUSION: RS4 could be used as a functional ingredient to replace up to 40% of hard wheat flour for making Asian noodles while maintaining their hardness after cooking. The extensibility of cooked noodles with high RS4 could be noticeably enhanced by supplementation with vital wheat gluten in the composite flour (RS/flour = 40/60). © 2020 Society of Chemical Industry.

Changes in protein and starch digestibility in sorghum flour during heat-moisture treatments.

BACKGROUND: Heat-moisture treatment (HMT) has been used to modify properties of sorghum starches. However, information is limited on the effects of HMT on the digestibility of starch and the concurrent changes in protein in sorghum flour. The objectives of this research were to identify heat-moisture conditions to increase the resistant starch (RS) content of sorghum flour and investigate changes in sorghum proteins and starch structure. RESULTS: Sorghum flours with different moisture contents (0, 125, 200, and 300 g kg-1 w.b.) were heated at three temperatures (100, 120 and 140 °C) and times (1, 2 and 4 h). HMT of sorghum flour increased its RS level. The flour treated at 200 g kg-1 moisture and 100 °C for 4 h had a high RS content (221 g kg-1 vs. 56 g kg-1 for the untreated flour). Starch was not gelatinized when sorghum flours heated at moisture content of 200 g kg-1 or below. Sorghum protein digestibility and solubility decreased during HMT. The increase in RS of sorghum flour upon HMT was attributed to enhanced amylose-lipid complexes and heat induced structural changes in its protein fraction. CONCLUSION: HMT can be used to increase RS content in sorghum flour without gelatinizing its starch, thereby providing sorghum flour with unique food applications. © 2017 Society of Chemical Industry.