Influence of marine hydrocolloids on extruded and native wheat flour pastes and gels

Assembly of soy protein-corn starch composite gels by thermal induction: Structure, and properties

The effect of different corn starch (CS) concentrations on the gel formation of soybean isolate protein (SPI) was investigated. Moreover, the texture, rheological properties of the gel were determined, and the spatial structure and interactions of the composite gel system were analyzed. The composite system transitioned from liquid to solid-like with an increase in the CS concentration and did not backflow when inverted for 24 h. With the addition of CS, the gel strength, water holding capacity (WHC), G', and G'' increased significantly. The maximum was reached at 10 % starch concentration with gel strength of (228.96 ± 29.86) g and WHC of (98.93 ± 2.02)  %. According to low-field 1H nuclear magnetic resonance (LF-NMR) results, CS has a high water absorption capacity, which improved the WHC. The scanning electron microscopy results revealed that composite gels with a high CS concentration had a more dense and small void network structure. According to the results of molecular force interaction, infrared spectroscopy, Raman spectroscopy, and free sulfhydryl group analysis, the added starch promoted the unfolding of SPI molecules, exposure of hydrophobic groups, transformation of free sulfhydryl groups into disulfide bonds, and hydrogen bond formation. Hydrophobic interactions, disulfide bonding, and hydrogen bonding function together to form the SPI-CS composite gel system. The study results provide the basis for applying soy protein and CS gels.

Effect of continuous instant pressure drop treatment on the rheological properties and volatile flavor compounds of whole highland barley flour

Continuous instant pressure drop (CIPD) treatment effectively reduces microbial contamination in whole highland barley flour (WHBF). Base on it, this study further investigated its effects on flour properties (especially rheological properties) and volatile compounds (VOCs) profile of WHBF, and compared it with that of ultraviolet-C (UV-C), ozone and hot air (HA) treatments. The results showed that the damaged starch content (6.0%) of CIPD-treated WHBF was increased, leading to a rough surface and partial aggregation of starch particle, thereby increasing the particle size (18.06 μm of D10, 261.46 μm of D50 and 534.44 μm of D90). Besides, CIPD treatment exerted a positive influence on the structure and rheological properties of WHBF, including an elevation in pasting temperature and viscosity. Notably, CIPD-treated WHBF exhibited higher storage modulus and loss modulus compared to the other three groups of sterilization treatments, contributing to the formulation of a better-defined and stable gel strength (tan δ = 0.38). UV-C and ozone, as cold sterilization techniques, also induced alterations in specific characteristics of WHBF. UV-C treatment led to changes in WHBF's crystallinity, while ozone treatment caused modifications in the secondary protein structure of WHBF. A total of 68 VOCs were identified in raw WHBF (including 3 acids, 19 alcohols, 25 aldehydes, 1 alkene, 8 esters, 2 ethers, 3 furans, and 7 ketones). The maximum flavor-contributing VOC in CIPD-treated WHBF remained dimethyl sulfide monomer (cabbage aroma), consistent with the raw WHBF. Conversely, in HA-treated WHBF, the maximum flavor-contributing VOC shifted to 2-furanmethanethiol monomer (roasted coffee aroma), altering the initial flavor presentation. These findings will provide strong support for the application of CIPD technology in the powdery foods industry.

The use of hydrogel structures in production of extruded rice and investigation of its qualitative characteristics

The aim of this study was to investigate the quality parameters of extruded rice containing hydrogel and comparing with natural rice (Hashemi variety rice). Extruded rice was produced with composite hydrogel (gellan, xanthan and sodium alginate) at the concentrations of 0.0 (control sample), gellan (0.5%)-alginate (0.5%) (GA1), gellan (1%)-alginate (1%) (GA2), gellan (0.5%)-alginate (0.5%)-xanthan (0.1%) (GAX 1%), and gellan (1%)-alginate (1%)-xanthan (0.2%) (GAX2%). The use of hydrogels had no significant effect on moisture content, ash content, cooking time, and color properties of extruded rice (p ≥ .05). In contrast, hydrogel significantly increased water absorption ratio (WAR), water solubility index (WSI), water absorption index (WAI), and textural properties (p ˂ .05) of extruded rice. This observation supports the highest score found for extruded rice containing GA2% and GAX2% in sensory properties, which were similar to natural rice. GA2% rice sample showed the similar texture characteristic, cooking feature, and color parameter to natural rice, ultimately, showing better organoleptic properties.

Study of the Effects Induced by Ball Milling Treatment on Different Types of Hydrocolloids in a Corn Starch-Rice Flour System

The effects of ball milling treatment on both the structure and properties of guar gum (GG), tara gum (TG), and methylcellulose (MC) were analyzed prior to assessing their potential interactions with starch components when they are used alone or in blends in a corn starch-rice flour system. X-ray diffraction profiles showed that the ball milling caused a reduction in the crystallin domain and, in turn, a diminished viscosity of the GG aqueous solutions. Despite an increase in its viscosity properties, effects on TG were minimal, while the milled MC exhibited reduced crystallinity, but similar viscosity. When both milled and un-milled hydrocolloids were individually added to the starch-flour system, the pasting properties of the resulting mixtures seemed to be affected by the type of hydrocolloid added rather than the structural changes induced by the treatment. All hydrocolloids increased the peak viscosity of the binary blends (especially pure GG), but only milled and un-milled MC showed values of setback and final viscosity similar to those of the individual starch. Ball milling seemed to be more effective when two combined hydrocolloids (milled GG and MC) were simultaneously used. No significant differences were observed in the viscoelastic properties of the blends, except for un-milled GG/starch, milled TG/starch, and milled MC/milled TG/starch gels.