The Effect of Wet Milling and Cryogenic Milling on the Structure and Physicochemical Properties of Wheat Bran

Stabilisation of vitamin A by wheat bran is affected by wheat bran antioxidants, bound lipids and endogenous lipase activity

Food fortification is an efficient strategy to combat vitamin A deficiency. However, the stability of vitamin A during storage is low. Cereal bran can be used as a natural and affordable stabilising agent, but the mechanism behind this stabilisation remains unclear. To unravel this mechanism, vitamin A stabilisation was studied during an accelerated storage experiment (60 °C, 70% relative humidity) using a set of 30 in-house modified wheat bran samples. The characteristics of these samples were linked to vitamin A stabilisation during storage using forward regression modelling. While all wheat bran samples could stabilise vitamin A to a significant extent, the stabilising effect was more pronounced for samples with a high antioxidant capacity, high bound lipid content and low lipase activity. The main effect of lipase activity was more than thrice as large as the main effects of antioxidant capacity and bound lipid content. These results suggest that wheat bran antioxidants and bound lipids protect vitamin A from degradation during storage, while endogenous lipase activity counteracts the stabilising effect. Based on these findings, modified wheat bran mixed with vitamin A can be a cost-effective and healthy aid in food fortification by providing high vitamin A stability.

Milling of buckwheat hull to cell-scale: Influences on the behaviors of protein and starch in dough and noodles

Superfine grinding of insoluble dietary fiber (IDF) is a promising method to improve the product quality by regulating the interaction between protein and starch. In this study, the effects of buckwheat-hull IDF powder, at cell-scale (50-10 μm) and tissue-scale (500-100 μm), on the dough rheology and noodle quality were investigated. Results showed that cell-scale IDF with higher exposure of active groups increased the viscoelasticity and deformation resistance of the dough, due to the aggregation of protein-protein and protein-IDF. Compared with the control sample, the addition of tissue-scale or cell-scale IDF significantly increased the starch gelatinization rate (β, C3-C2) and decreased the starch hot-gel stability. Cell-scale IDF increased the rigid structure (β-sheet) of protein, thus improving the noodle texture. The decreased cooking quality of cell-scale IDF-fortified noodles was related to the poor stability of rigid gluten matrix and the weakened interaction between water and macromolecules (starch and protein) during cooking.

Anaerobic fermentation featuring wheat bran and rice bran realizes the clean transformation of Chinese cabbage waste into livestock feed

Rapid aerobic decomposition and a high cost/benefit ratio restrain the transformation of Chinese cabbage waste into livestock feed. Herein, anaerobically co-fermenting Chinese cabbage waste with wheat bran and rice bran at different dry matter levels (250, 300, 350 g/kg fresh weight) was employed to achieve the effective and feasible clean transformation of Chinese cabbage waste, and the related microbiological mechanisms were revealed by high-throughput sequencing technology. The bran treatments caused an increase in pH value (4.75-77.25%) and free amino acid content (12.09-152.66%), but a reduction in lactic acid concentration (54.58-77.25%) and coliform bacteria counts (15.91-20.27%). In addition, the wheat bran treatment improved the levels of short-chain fatty acids, nonprotein nitrogen, water-soluble carbohydrates and antioxidant activity and reduced the ammonia nitrogen contents. In contrast, the rice bran treatment decreased the levels of acetic acid, water-soluble carbohydrates, nonprotein nitrogen, ammonia nitrogen, and antioxidant activities. Microbiologically, the bran treatments stimulated Pediococcus, Lactobacillus, Enterobacter, and Weissella but inhibited Lactococcus and Leuconostoc, which were the primary organic acid producers reflected by the redundancy analysis. In addition, Chinese cabbage waste fermented with wheat bran at 350 g/kg fresh weight or with rice bran at 300 g/kg fresh weight increased the scale and complexity of bacteriome, promoted commensalism or mutualism and upregulated the global metabolism pathways, including carbohydrate and amino acid metabolisms. Furthermore, the bran treatments resulted in an increase in bacterial communities that were facultatively anaerobic, biofilm-formed, Gram-negative, potentially pathogenic and stress-tolerant. Collectively, the bran treatments inhibited effluent formation and protein degradation and improved nutrient preservation but reduced organic acid production during the anaerobic fermentation, which is linked to the variations in the bacteriome, indicating that the constructed fermentation system should be further optimized.

Encapsulation of Lactobacillus acidophilus in solid lipid microparticles via cryomilling

We herein delved into the microencapsulation of Lactobacillus acidophilus (LA) into solid lipid microparticles (SLMs) via the cryomilling technique. For this aim, a frozen lipid mixture containing LA was pulverized at different times (7, 14, 21, 28, and 35 min) using a cryogenic mixer mill to produce probiotic-loaded SLMs. The impacts of different cryomilling durations on the SLMs properties (morphology, particle size, water activity, polymorphism, crystallinity, and thermal behavior) and the viability of LA were evaluated. Microencapsulation improved the viability of LA in simulated gastrointestinal fluids, heat stress, and different concentrations of salt and sucrose. SLMs also were suitable to be incorporated into foods. However, once the cryomilling time was prolonged, the viability of encapsulated LA declined, and particle size grew. The cryomilling technique showed great potential as an alternative approach for encapsulation due to the lack of solvent, short processing time, and simplicity.

Alteration in dough volume and gluten network of lychee pulp pomace bread base on mixture design dominated by particle size

The reducing flavor of whole grain bread has been constantly affecting the consumption desire of a significant proportion of consumers. The study presents the use of lychee pulp pomace (LPP) powder to replace certain proportion of wheat flour and produce wheat bread with better quality, while having minimal effects on the volume and improving the nutritional quality. Distinct particle sizes (60-400 µm) of LPP powder were obtained by superfine or ordinary grinding. Effect of different additive proportions (7-19%) of LPP powder on bread dough quality were studied by constrained mixture designs. The volume of fermented doughs subsequently decreased after adding LPP powder. However, LPP powders with smaller particle sizes were able to minimize this effect due to its higher water-holding capacity. The analyses of gluten network showed that smaller particle sizes of LPP powder resulted in a decrease in surface hydrophobicity and increase in the elasticity and stability of gluten network. Finally, optimum mixture formula was composed of 16% LPP powder with 60 µm particle size and 15% water. The study illustrated the potential to make high-quality bread with small particle size of LPP powder. PRACTICAL APPLICATION: The addition of dietary fiber to wheat flour can adversely affect the dough volume and reduce the dough quality. By reducing the particle size of lychee pulp pomace powder, this adverse effect could be minimized while increasing the content of dietary fiber and bound phenolics in the dough. This provides data for the production of high-quality lychee dough bread.

Quality Characteristics and Antioxidant Activity of Fresh Noodles Formulated with Flour-Bran Blends Varied by Particle Size and Blend Ratio of Purple-Colored Wheat Bran

This study explored the noodle-making performance of flour blends with different particle sizes and blending ratios of purple-colored wheat bran and their antioxidant properties. The bran particle size was reduced using an ultra-centrifugal mill equipped with 1, 0.5, and 0.2 mm sieves. The damaged starch and swelling capacity of the bran were analyzed. Quality of the flour-bran blends at different blending ratios was analyzed by solvent retention capacity (SRC). Noodles made from the blends and their corresponding antioxidant activities were examined. The damaged starch and swelling capacity of bran were higher for smaller particles than for larger particles. Water and sodium carbonate SRC values of blends increased as the bran particle size decreased. The smaller the bran particles incorporated in the cooked noodles, the greater firmness and springiness measured. The antioxidant activity of noodles made with blends reflected better embedding of the small particles of bran than the large particles into noodle sheets. Small bran particles significantly enhanced noodles’ quality and antioxidant activity at higher blending ratios than large bran particles. Particle size reduction of bran enhanced the noodle-making performance of flour blended with purple-colored wheat bran; this could increase the utilization of bran to produce noodles with health benefits.

Process-Induced Changes in the Quantity and Characteristics of Grain Dietary Fiber

Daily use of wholegrain foods is generally recommended due to strong epidemiological evidence of reduced risk of chronic diseases. Cereal grains, especially the bran part, have a high content of dietary fiber (DF). Cereal DF is an umbrella concept of heterogeneous polysaccharides of variable chemical composition and molecular weight, which are combined in a complex network in cereal cell walls. Cereal DF and its distinct components influence food digestion throughout the gastrointestinal tract and influence nutrient absorption and other physiological reactions. After repeated consumption of especially whole grain cereal foods, these effects manifest in well-demonstrated health benefits. As cereal DF is always consumed in the form of processed cereal food, it is important to know the effects of processing on DF to understand, safeguard and maximize these health effects. Endogenous and microbial enzymes, heat and mechanical energy during germination, fermentation, baking and extrusion destructurize the food and DF matrix and affect the quantity and properties of grain DF components: arabinoxylans (AX), beta-glucans, fructans and resistant starch (RS). Depolymerization is the most common change, leading to solubilization and loss of viscosity of DF polymers, which influences postprandial responses to food. Extensive hydrolysis may also remove oligosaccharides and change the colonic fermentability of DF. On the other hand, aggregation may also occur, leading to an increased amount of insoluble DF and the formation of RS. To understand the structure–function relationship of DF and to develop foods with targeted physiological benefits, it is important to invest in thorough characterization of DF present in processed cereal foods. Such understanding also demands collaborative work between food and nutritional sciences.