Evaluation of rheological properties, microstructure and water mobility in buns dough enriched in aleurone flour modified by enzyme combinations

Recent advances in enzymatic modification techniques to improve the quality of flour-based fried foods

Flour-based fried foods are among the most commonly consumed foods worldwide. However, the sensory attributes and nutritional value of fried foods are inconsistent and unstable. Therefore, the creation of fried foods with desirable sensory attributes and good nutritional value remains a major challenge for the development of the fried food industry. The quality of flour-based fried foods can sometimes be improved by physical methods and the addition of chemical modifiers. However, enzyme modification is widely accepted by consumers due to its unique advantages of specificity, mild processing conditions and high safety. Therefore, it is important to elucidate the effects of enzyme treatments on the sensory attributes (color, flavor and texture), oil absorption and digestibility of flour-based fried foods. This paper reviews recent research progress in utilizing enzyme modification to improve the quality of flour-based fried foods. This paper begins with the effects of common enzymes on the physicochemical properties (rheological property, retrogradation property and specific volume) of dough. Based on the analysis of the mechanism of formation of sensory attributes and nutritional properties, it focuses on the application of amylase, protease, transglutaminase, and lipase in the regulation of sensory attributes and nutritional properties of flour-based fried foods.

Effects of Co-Modification by Extrusion and Enzymatic Hydrolysis on Physicochemical Properties of Black Wheat Bran and Its Prebiotic Potential

Black wheat bran (BWB) is an important source of dietary fiber (DF) and phenolic compounds and has stronger nutritional advantages than ordinary WB. However, the low content of soluble dietary fiber (SDF) negatively influences its physicochemical properties and nutritive functions. To obtain a higher content of SDF in BWB, we evaluated the impact of co-modification by extrusion and enzymes (cellulase, xylanase, high-temperature α-amylase, and acid protease) on water extractable arabinoxylan (WEAX) in BWB. An optimized co-modification method was obtained through single-factor and orthogonal experiments. The prebiotic potential of co-modified BWB was also evaluated using pooled fecal microbiota from young, healthy volunteers. The commonly investigated inulin served as a positive control. After co-modification, WEAX content was dramatically increased from 0.31 g/100 g to 3.03 g/100 g (p < 0.05). The water holding capacity, oil holding capacity, and cholesterol adsorption capacity (pH = 2.0 and pH = 7.0) of BWB were increased by 100%, 71%, 131%, and 133%, respectively (p < 0.05). Scanning electron microscopy demonstrated a looser and more porous microstructure for co-modified BWB granules. Through in vitro anerobic fermentation, co-modified BWB achieved a higher content of Bifidobacterium and Lactobacillus than inulin fermentation. In addition, co-modified BWB induced the highest butyric acid production, indicating high potential as prebiotics. The results may contribute to improving technologies for developing high-fiber-content cereal products.

Influence of α-amylase, xylanase and cellulase on the rheological properties of bread dough enriched with oat bran

A better understanding of dough rheology during processing is crucial in the bakery industry, since quality attributes of the final product are influenced by those properties. In this study, we investigated the effects of xylanase, α-amylase and cellulase on the rheological properties of bread dough enriched in oat bran. A DoughLAB was used to measure the mixing characteristics of dough. According to the results, adding a single enzyme did not significantly affect the water absorption, development time, or stability of oat bran dough. In contrast, when blended enzymes were used at high concentrations (10, 120, and 60 ppm), the water absorption, development time, and stability of the oat bran dough were significantly reduced compared to using the single enzyme (62.1%, 7.1 and 6.6 min). It was found that combining α-amylase, xylanase and cellulase resulted in better extensibility and stickiness (16.5 mm and 60.8 g) of oat bran dough than using these enzymes individually. As a result, α-amylase, xylanase and cellulase complemented each other in determining the rheology of bread dough.

Wheat bran layers: composition, structure, fractionation, and potential uses in foods

Wheat bran, the main by-product of dry milling of wheat, is currently mainly used in the animal feed industry, but has attracted attention as a food ingredient owing to its high dietary fiber and phytochemical contents, providing excellent physiological effects. The bran layers (aleurone layer, outer pericarp and intermediate layer) contain different compositions, structures, and nutrients, and have different properties. Each layer, when separated and isolated, potentially could find more extensive applications in foods. This triggered interest in isolating the bran layers using milling and wet- or dry-fractionation techniques based on their chemical or physical properties. The recent progress has allowed the production of commercial products from wheat bran layers, particularly aleurone-rich products, enhancing the value of wheat bran layers and their applications in food. The present review highlights the recent advances in studying the chemical composition including distribution of chemical components, physical structure, biopolymer matrix, and physicochemical properties of each wheat bran layer. Technologies to fractionate wheat bran layers and utilization of different bran layers in foods are discussed and reviewed, providing new strategies for improving the value of wheat bran and utilization of wheat bran in foods.

Empirical and Theoretical Bases of Good Steamed Bread Production

Chinese steamed bread (CSB) is a main staple food in China, accounting for 40% of wheat flour usage in China. Due to its health benefits, CSB is gaining popularity across the world. In this review, the effects of gluten proteins (particularly glutenins and gliadins) on the quality of CSB are summarized from the literature. Requirements of appropriate rheological parameters in different studies are compared and discussed. Along with the increasing demand for frozen storage food, there are obvious increases in the research on the dynamics of gluten proteins in frozen dough. This review also summarizes the factors influencing the deterioration of CSB dough quality during frozen storage as well as effective measures to mitigate the negative effects.

The Wheat Aleurone Layer: Optimisation of Its Benefits and Application to Bakery Products

The wheat aleurone layer is, according to millers, the main bran fraction. It is a source of nutritionally valuable compounds, such as dietary fibres, proteins, minerals and vitamins, that may exhibit health benefits. Despite these advantages, the aleurone layer is scarce on the market, probably due to issues related to its extraction. Many processes exist with some patents, but a choice must be made between the quality and quantity of the resulting product. Nonetheless, its potential has been studied mainly in bread and pasta. While the nutritional benefits of aleurone-rich flour addition to bread agree, opposite results have been obtained concerning its effects on end-product characteristics (namely loaf volume and sensory characteristics), thus ensuing different acceptability responses from consumers. However, the observed negative effects of aleurone-rich flour on bread dough could be reduced by subjecting it to pre- or post-extracting treatments meant to either reduce the particle size of the aleurone's fibres or to change the conformation of its components.

The Impact of Germinated Chickpea Flour Addition on Dough Rheology and Bread Quality

The research focused on the effect of germinated chickpea flour (GCF) in a lyophilized form on dough rheology, microstructure and bread quality. The GCF addition levels in refined wheat flour with a low α-amylase activity were 5%, 10%, 15% and 20%, up to an optimum falling number value of the mixed flour. Generally, the dough rheological properties of water absorption, tolerance to mixing, dough consistency, dough extensibility, index of swelling, baking strength and loss tangent (tan δ) for the temperature sweep test decreased with the increased level of GCF addition, whereas the total volume of gas production and G′ and G″ modules for the temperature sweep test increased. Dough microstructure analyzed by epifluorescence light microscopy (EFLM) clearly showed a change in the starch and gluten distribution from the dough system by an increase in protein and a decrease in starch granules phase with the increased level of GCF addition in wheat flour. The bread physical characteristics (loaf volume, porosity, elasticity) and sensory ones were improved with up to 15% GCF addition in wheat flour. The bread firmness increased, whereas the bread gumminess, cohesiveness and resilience decreased with increased GCF addition in wheat flour. The bread crust and crumb color of the bread samples become darker with an increased GCF addition in the bread recipe.