Influences of hydrothermal and pressure treatments on compositional and hydration properties of wheat bran and dough mixing properties of whole wheat meal

The Influence of Processing Using Conventional and Hybrid Methods on the Composition, Polysaccharide Profiles and Selected Properties of Wheat Flour Enriched with Baking Enzymes

In this study, a developed wheat flour blend (F), consisting of a high content of non-starch polysaccharides, was fortified with cellulase (C) and a cellulase-xylanase complex (CX) and then processed via conventional and hybrid treatment methods. Dry heating (T), hydrothermal treatment (H) and extrusion processing (E) were applied without or with enzyme addition as hybrid treatments. Proximate composition and polysaccharide profiles selected techno-functional and structural properties of modified wheat flours, were analyzed. Conventional and hybrid treatments induced changes in polysaccharide fraction compositions (especially the arabinoxylans) and the rheology of modified flour. Dry heating caused an inconsiderable effect on flour composition but reduced its baking value, mainly by reducing the elasticity of the dough and worsening the strain hardening index, from 49.27% (F) to 44.83% (TF) and from 1.66 (F) to 1.48 (TF), respectively. The enzymes added improved the rheological properties and baking strength, enhancing the quality of gluten proteins. Hydrothermal enzyme-assisted treatment increased flour viscosity by 14-26% and improved the dough stability by 12-21%; however, the use of steam negatively affected the protein structure, weakening dough stretchiness and elasticity. Extrusion, especially enzyme-assisted, significantly increased the hydration properties by 55-67% but lowered dough stability, fat content and initial gelatinization temperature due to the changes in the starch, mostly induced by the hybrid enzymatic-extrusion treatment. The structure of extruded flours was different from that obtained for other treatments where the peak intensity at 20° was the highest, suggesting the presence of amorphous phases of amylose and lipids. The results can be helpful in the selection of processing conditions so as to obtain flour products with specific techno-functional properties.

Functional and Nutritional Characteristics of Natural or Modified Wheat Bran Non-Starch Polysaccharides: A Literature Review

Wheat bran (WB) consists mainly of different histological cell layers (pericarp, testa, hyaline layer and aleurone). WB contains large quantities of non-starch polysaccharides (NSP), including arabinoxylans (AX) and β-glucans. These dietary fibres have long been studied for their health effects on management and prevention of cardiovascular diseases, cholesterol, obesity, type-2 diabetes, and cancer. NSP benefits depend on their dose and molecular characteristics, including concentration, viscosity, molecular weight, and linked-polyphenols bioavailability. Given the positive health effects of WB, its incorporation in different food products is steadily increasing. However, the rheological, organoleptic and other problems associated with WB integration are numerous. Biological, physical, chemical and combined methods have been developed to optimise and modify NSP molecular characteristics. Most of these techniques aimed to potentially improve food processing, nutritional and health benefits. In this review, the physicochemical, molecular and functional properties of modified and unmodified WB are highlighted and explored. Up-to-date research findings from the clinical trials on mechanisms that WB have and their effects on health markers are critically reviewed. The review points out the lack of research using WB or purified WB fibre components in randomized, controlled clinical trials.

Effect of subcritical water flash release processing on buckwheat flour properties

BACKGROUND

Buckwheat (Fagopyrum esculentum) is rich in bioactive components. However, many of these components are trapped within cellular structures, making them inaccessible. Buckwheat flour was hydrothermally modified using subcritical water coupled with a flash pressure release (SCWF). The effects of the SCWF parameters (120, 140, and 160 °C and hold times of 0, 15, and 30 min) on the flour's structure, physicochemical, and functional properties were studied relative to the raw flour.

RESULTS

Treatment deepened the flour color with increasing processing temperatures and hold times. Starch content remained unchanged though its granular structure was disrupted. SCWF treatments lowered total phenolic content compared with the raw flour, except for 160 °C-30 min, where total phenolic content increased by 12.7%. The corresponding antioxidant activities were found consistent with phenolic content. Soluble and insoluble dietary fiber amounts were not substantially influenced at 120 and 140 °C, whereas treatments at 160 °C (15 and 30 min hold) decreased soluble dietary fiber while increasing insoluble dietary fiber. Protein content increased 70-109% in some treatments, suggesting greater protein accessibility. Water-holding capacity significantly increased for flour treated at 120 °C, whereas only slight improvements occurred at 140 and 160 °C.

CONCLUSIONS

Subcritical water flash processing can modify the compositional and functional properties of buckwheat flour depending on the choice of reaction conditions. Observed changes were consistent with alteration of the flour's cellular structure and allow some components to become more accessible. The resulting SCWF-modified buckwheat flours provide new food ingredients for potential use in ready-to-eat foods and spreads with improved health benefits. Published 2022. This article is a U.S. Government work and is in the public domain in the USA.