Effect of dietary fibre enrichment on selected properties of gluten-free bread

The enrichment of gluten-free baked products with dietary fibre seems to be necessary since it has been reported that coeliac patients have generally a low intake of fibre due to their gluten-free diet. In the present study different cereal fibres (wheat, maize, oat and barley) were added at 3, 6 and 9 g/100 g level into a gluten-free bread formulation based on corn starch, rice flour and hydroxypropyl methyl cellulose (HPMC). Doughs were evaluated based on consistency, viscosity and thermal properties. Results showed that maize and oat fibre can be added to gluten-free bread with positive impact on bread nutritional and sensory properties. All breads with 9 g/100 g fibre increased the fibre content of control by 218%, but they were rated lower than those with 3 and 6 g/100 g fibre due to their powdery taste. The formulation containing barley fibre produced loaves that had more intense color and volume comparable to the control. During storage of breads a reduction in crumb moisture content and an increase in firmness were observed. The micrographs of the crumb showed the continuous matrix between starch and maize and/or oat fibre obtaining a more aerated structure.     

Effect of addition of protein concentrates from natural and yeast fermented rice bran on the rheological and technological properties of wheat bread

The effect of substituting wheat flour with 0%, 5%, 10% and 15% protein concentrates from natural and yeast fermented rice bran on the rheological properties of their dough and bread properties was studied. Rheological properties of wheat dough were influenced by addition of rice bran protein concentrates. Overall acceptability score and specific loaf volume of 100% wheat bread were not significantly different from composite bread up to 10% rice bran protein substitution, and therefore, the optimised level of substitution was established. The optimised composite bread contained higher total amino acid content, radical scavenging activity and ferric reducing ability power (43.04–48.87 g/100 g, 182.77–201.65   mmol TEAC/100 g and 613.29–637.81 mmol TE/100 g) than control (33.86 g/100 g, 109.43 mmol TEAC/100 g and 540.13 mmol TE/100 g). Springiness, cohesiveness and resilience values of wheat bread were not significantly different from composite bread. Scanning electron microscopy revealed that composite bread had surfaces with embedded granules like protein deposits with small spores.     

米糠蛋白的分离及其营养特性的研究

米糠中含有较高的蛋白质,其必需氨基酸组成近似于人体需要量模式,本文基于此原因,主要介绍了米糠蛋白的分离方法以及营养特性,相信米糠蛋白将成为食品工业的一种新型蛋白质。     

Processing of commercial rice bran for the production of fat and nutraceutical rich rice brokens,rice germ and pure bran

Successive sieving of commercial rice bran on the basis of particle size was performed and different fractions were obtained of which the rice brokens and rice germ fractions contained fat 33 g/kg and 207 g/kg, oryzanol 400 mg/kg and 874 mg/kg, total tocols (tocopherols and tocotrienols) 16.5 mg/kg and 87.8 mg/kg, and total phytosterols 128.7 mg/kg and 769.6 mg/kg respectively, thus indicating that these fractions are a good source of fat and nutraceuticals. The residual fat (6 g/kg) from commercial defatted rice bran contained high oryzanol content of 4.8 g/100 g, indicating that commercial defatted rice bran as a source of oryzanol. The fat from pure rice bran fraction of commercial rice bran decreased in the color value (48.5%) indicating that sieving could also improve the quality of crude rice bran oils.     

米糠贮藏时间对米糠蛋白功能性质影响

以新鲜米糠为原料,经不同时间贮藏后脱脂制备米糠蛋白,研究贮藏时间对制备米糠蛋白功能性质的影响。结果表明:随着贮藏时间的延长,米糠蛋白羰基含量增加,表明米糠蛋白在贮藏过程中发生了氧化;随着蛋白质氧化程度的加深,米糠蛋白溶解性下降,而米糠蛋白持水性、持油性、起泡能力、泡沫稳定性、乳化性和乳化稳定性均呈现先上升后下降的趋势,表明米糠在一定贮藏期内可部分改善米糠蛋白功能性质,而长时间贮藏则会对米糠蛋白功能性质有显著的负面影响。     

脱脂米糠膳食纤维的理化特性研究

测定了脱脂米糠膳食纤维（Ｂｆｉｂｒｅ）和市售糖甜菜纤维（ＦＩＢＲＥＸ）的持水力（ＷＢＣ）、结合脂肪的能力（ＦＢＣ）、乳化能力（ＥＣ）和粘度,并对所得数据进行了统计学分析,发现：Ｂｆｂｒｅ与ＦＩＢＲＥＸ相比有较高的ＥＣ和ＦＢＣ,它们的ＷＢＣ无显著差异（Ｐ＜０．０５）,但是Ｂｆｉｂｒｅ的粘度小于ＦＩＢＲＥＸ。这些数据表明Ｂｆｂｉｒｅ有更大的潜在应用价值,尤其在功能食品的发展中更为重要。     

Preparation of a rice bran enzymatic extract with potential use as functional food

The production, stabilization, by enzymatic treatment, physicochemical composition, and biological properties (including the anti-proliferative activity), of a water-soluble rice bran enzymatic extract (RBEE) are described. The main component of RBEE is proteins (38.1%) – in the form of peptide and free amino acids – having a 6% content of sulfur amino acids. The second component is fat (30.0%), with oleic and linoleic acids as the major components, and 1.2 mg/g of γ-oryzanol. Carbohydrates (14.2%) are comprised mainly of slowly absorbed carbohydrates. Preliminary studies on the anti-proliferative effect of RBEE on leukemia tumor cell growth in vitro are also reported. This property makes RBEE potentially useful as a functional food for the treatment and prevention of chronic pathological states associated with abnormal proliferation of cells, as is the case with cancer.     

富含挤压稳定化米糠粉面包的研制

研究了以挤压稳定化米糠粉为原料,生产面包的最适配方及技术条件。实验结果表明,添加10%的米糠粉可制得品质优良的面包。     

Characteristics of low-fat meat emulsion systems with pork fat replaced by vegetable oils and rice bran fiber

The effects of vegetable oils prepared from olive, corn, soybean, canola, or grape seed, and rice bran fiber on the composition and rheological properties of meat batters were studied. Pork fat at 30% in the control was partially replaced by one of the vegetable oils at 10% in addition to reducing the pork fat to 10%. The chemical composition, cooking characteristics, texture properties, and viscosity of low-fat meat batters were analyzed. The moisture, protein, ash content, uncooked and cooked pH values, b^∗-value, hardness, cohesiveness, gumminess, chewiness, and viscosity of meat batters with vegetable oil and rice bran fiber were all higher than the control. In addition, batters supplemented with vegetable oil and rice bran fiber had lower cooking loss and better emulsion stability. Low-fat meat batters with reduced pork fat content (10%) and 10% vegetable oil plus rice bran fiber had improved characteristics relative to the regular fat control.     

Nanofiltration process for the nutritional enrichment and refining of rice bran oil

Crude rice bran is a natural source of γ-oryzanol, a nutritionally valuable phytochemical with antioxidant properties. In the present paper the refining and γ-oryzanol enrichment of rice bran oil was investigated through solvent extraction optimization and nanofiltration processing. Several solvent resistant nanofiltration membranes were screened and successfully applied in a two step membrane cascade with fluxes between 39 and 53 L m⁻² h⁻¹. A first membrane stage operation provided the separation between glycerides and γ-oryzanol, promoting the oil enrichment in this phytochemical. In the second membrane stage the oil could be refined to acceptable consumption levels (FFA < 0.20 wt.%) and its γ-oryzanol content was further enhanced. Overall, the integrated process provided a RBO γ-oryzanol enrichment from 0.95 to 4.1 wt.% in oil, which corresponded to more than a two fold increase in the oil’s antioxidant capacity. These results demonstrate the potential of organic solvent nanofiltration as a technology to enrich and refine oil based products.     

Effect of rice bran fibre on the quality of rice pasta

This study investigated the effects of rice bran fibre (RBF) on the properties of rice pasta by extrusion processing. As the level of RBF increased, the content of total dietary fibre (TDF), insoluble dietary fibre (IDF) and soluble dietary fibre (SDF) increased, respectively. The difference in the content of ΔIDF between before and after extrusion decreased from 1.01% to 0.69% and that of ΔSDF decreased from 1.06% to 0.55%. Depending on the increasing level of RBF, the water absorption index decreased and water solubility index increased, respectively. The crystallinity of newly formed crystals decreased from 21.43% to 18.66% as the level of RBF increased. Adding RBF darkened the colour of rice pasta and reduced its hardness and chewiness. The cooking loss (CL) increased significantly compared with the control (0% RBF). The results indicate that rice pasta with extra RBF (up to 15%) can provide an acceptable quality product with a satisfactory colour and CL.     

Effect of dry heat stabilisation on the functional properties of rice bran proteins

Rice bran was stabilised by dry heat method at 120 °C for 10–60 min, and then, protein was extracted from stabilised rice bran using weak alkali method. The storage characteristics of stabilised rice bran and the influences of dry heat pretreatment on the physicochemical properties of rice bran protein isolate were also evaluated. The results indicated that dry heat pretreatment could not only prevent rancidity of rice bran effectively, but also improve some functional properties of rice bran proteins, such as emulsifying properties, oil holding capacity, and water holding capacity. However, foaming properties and protein solubility were slightly destroyed because of heating. Rice bran was pretreated at 120 °C for 10 or 20 min and then extracted at pH 9.5, and the protein yields were 50.09% and 46.98%, respectively. Therefore, the dry heat treatment at 120 °C for 10 or 20 min was a suitable alternative process in stabilisation of rice bran.     

Phytochemicals and antioxidant properties of solvent extracts from Japonica rice bran

The yield, major phytochemicals (oryzanols, tocopherols (T), and tocotrienols (T3)) and antioxidant properties of Japonica rice bran extracts were investigated, for illustrating the major effects from solvent property. Generally, the extract yield varied with the solvent used in the order of methanol (MeOH) > ethyl acetate (EtOAc) > hexane. In contrast to hexane extracts, both MeOH and EtOAc extracts exhibited a higher total content in phenolic compounds (∼2.5 g gallic acid equivalent/kg bran), oryzanols (1.6–1.8 g/kg bran), or tocols (126–130 mg/kg bran), and a higher T3% in tocols (24–26%). The MeOH extract (at 1 mg/ml) showed the greatest capability in inhibiting linoleic acid peroxidation (57%), scavenging DPPH radicals (93%), reducing power (78%), and Fe²⁺ chelating activity (∼1300 μg EDTA equivalent/g) than the other two extracts, partly attributed to its high antioxidant contents. It is newly found that the yield, total content in phenolic compounds, oryzanols, and tocols, and T3% in tocols of the extracts increased with increasing Synder’s polarity value in a quite good linear manner (R² = 0.923–1.000), associated with an increased solvent viscosity. This clearly suggests the potential of using Synder’s polarity value as an index in isolation of desired rice bran phytochemical extracts.     

Oxidative stability of fried dough from rice flour containing rice bran powder during storage

The aim of this study was to evaluate the efficiency of rice bran powder on lipid peroxidation inhibition of fried dough from rice flour during storage. Rice flour dough containing rice bran powder at 5, 10 and 15 g rice bran powder/100 g mixed rice flour were fried in soybean oil at 160 °C for 1 min and stored in dark at 60 °C for 10 days. Lipid peroxidation of fried dough was determined by change of fatty acid compositions, oxygen absorption in vial headspace, lipid hydroperoxides, TBA values including decreasing tocopherol and gamma-oryzanol contents during storage. Polyunsaturated fatty acid decreased rapidly in fried dough without rice bran powder, while an increase of oxygen absorption in vial headspace, lipid hydroperoxide and TBA values were significantly lower (p?0.05) in fried dough containing rice bran powder. In addition, tocopherol degradation was significantly lower in fried dough containing rice bran powder during storage (p?0.05). However, there was no significant difference in gamma-oryzanol contents among fried dough during storage (p>0.05). These results demonstrated that rice bran powder shows the antioxidative effects on fried dough during storage.     

Sourdough fermentation as a tool for the manufacture of low-glycemic index white wheat bread enriched in dietary fibre

Three Lactobacillus strains were selected and used together as sourdough starter. Sourdough performances were evaluated for 30 days. Three breads were manufactured: wheat sourdough bread (WSB), WSB enriched with oat and rye fibres (WSB-DF) and wheat yeasted bread (WYB) fermented with baker’s yeast alone. WSB-DF and WSB showed higher specific volume and lower firmness than WYB. Sensory analysis showed that WSB-DF and WSB were preferred due to acidulous smell, taste and aroma. Compared to WYB and WSB, WSB-DF had high level of dietary fibre (DF). WYB was used as the control to estimate the hydrolysis index (HI = 100). WSB-DF had values of HI lower than WSB (59 vs. 86%). As estimated on 20 volunteers, the value of GI for WSB-DF was ca. 41%. WSB-DF bread manufactured at industrial plant combined low-GI with physiologically significant supply of DF and high standard structure and sensory features.     

Isolation and characterization of protein fractions from deoiled rice bran

Rice bran contains underutilised protein materials. Sequential extraction of rice bran protein (RBP) from defatted rice bran was conducted based on the differences in their solubility. Three extraction methods were investigated. Method 1 involved the isoelectric and acetone precipitation using water, 50 g kg⁻¹ NaCl, 0.02 mol L⁻¹ NaOH and 70% ethanol as extracting solvents for albumin (pH 4.1), globulin (pH 4.3), glutelin (pH 4.8) and prolamin, respectively. Method 2 adopted dialysis and sequential extraction was carried out with 20 g kg⁻¹ NaCl, 70% ethanol, 0.1 mol L⁻¹ acetic acid and 0.1 mol L⁻¹ NaOH solution as extracting solvents. Method 3 combined dialysis, isoelectric and acetone precipitation for the extraction. Based on the yields and data obtained from sodium dodecyl sulphate polyacrylamide gel electrophoresis, size-exclusion chromatography and differential scanning calorimetry, method 3 was chosen for the isolation and characterization of RBPs. Rice bran protein fraction (RBPF)—albumin, globulin, glutelin and prolamin were obtained in good yields. Denaturation temperature and enthalpy values of denaturation of RBPF vary. Highest phytate content was found in albumin and lowest in prolamin. The highest antioxidative and hemagglutinating activities were observed in albumin.     

Functional peptides derived from rice bran proteins

Rice bran has been predominantly used in the feed industry, and only recently it has attracted greater attention in terms of human nutrition with increasing knowledge of its bioactivity. A growing interest is the analysis of physiologically active peptides derived from rice bran proteins. In this paper, the bioactivities of rice bran proteins hydrolysates and peptides are reviewed based on recent studies. These enzymatic hydrolysates and peptides exert various biological activities including antioxidant, antidiabetic, anticancer and inhibitory activity for angiotensin converting enzyme (ACE), which may ultimately prevent certain chronic diseases. Nevertheless, these functionalities can be highly associated with their corresponding structural characteristics, in particular specific sequences and molecular weight distribution. This article may facilitate the expansion of the prospective applications of the bioactive peptides in a number of fields and provide some clues of the relationship between peptides structure and functionality for future research.     

Optimization of replacing pork back fat with grape seed oil and rice bran fiber for reduced-fat meat emulsion systems

The effects of reducing pork fat levels from 30% to 20% and partially substituting the pork fat with a mix of grape seed oil (0%, 5%, 10% and 15%) and 2% rice bran fiber were investigated based on chemical composition, cooking characteristics, physicochemical and textural properties, and viscosity of reduced-fat meat batters. For reduced-fat meat batters containing grape seed oil and rice bran fiber the moisture and ash contents, uncooked and cooked pH values, yellowness, cohesiveness, gumminess, chewiness, and sarcoplasmic protein solubility were higher than in the control samples. The reduced-fat samples with increasing grape seed oil concentrations had lower cooking loss, emulsion stability, and apparent viscosity. The incorporation of grape seed oil and rice bran fiber successfully reduced the animal fat content in the final products while improving other characteristics.     

米糠膳食纤维对强化大米质构的影响

以早籼米为原料,将米糠膳食纤维以不同浓度添加至粉碎后的大米粉中,混匀,采用"挤压强化法"制备米糠膳食纤维营养强化大米.通过对比早籼米与制得的营养强化大米炊饭后的质构特性(硬度、弹性、内聚性、胶着性和咀嚼性),确定米糠膳食纤维营养强化大米品质最佳时膳食纤维的添加量.结果表明:膳食纤维添加量为4%时,强化大米各项指标与原料早籼米最为接近;膳食纤维的添加量对强化大米的硬度、胶着性和咀嚼性影响较大,对应指标随膳食纤维添加量的增加呈先减小后增大的趋势;但米糠膳食纤维的加入对强化大米弹性和内聚性影响较小.