Dephytinisation of rice bran and manufacturing a new food ingredient

Rice bran was extruded at 130 °C and a screw speed of 140 rpm for 20 s to inactivate lipase and prevent lipid oxidation. Although the extrusion process induced further complex formation between phytic acid and protein as well as between phytic acid and starch, nearly 94% of phytic acid in the extruded rice bran could still be removed by solid/liquid extraction conducted at 25 °C for 30 min using hydrochloric acid at pH 2 as solvent and a solvent/rice bran ratio of 15. After the extract had been neutralised and phytic acid removed, it was added back to the rice bran solid to replenish the nutritional and functional components of the solid. The mixture was then dried in a drum dryer to yield a powdered product. The dephytinised rice bran product contained most of the protein, fat, dietary fibre and B vitamins and more than 50% of the oryzanol originally present in the raw rice bran. © 2001 Society of Chemical Industry     

Preparation of High Bran Arabic Bread with Low Phytic Acid Content

Incubation of wheat bran at pH 5.2 and at a temperature of 55°C for various periods of time caused an increase in the levels of inorganic phosphorus and inositol phosphates and a simultaneous decrease in the level of phytic acid. When Arabic bread containing different levels of bran was prepared, up to 32% of the original phytic acid was lost during the process of bread preparation. Incorporation of wheat malt in the bread formula did not have any effect on phytic acid loss while incubation of bran in an acidic medium followed by repeated decantation of the incubation liquid produced a high bran bread almost free of phytic acid.     

Rice Bran Stabilization by Extrusion Cooking for Extraction of Edible Oil

An extrusion cooking procedure was developed which produces stabie rice bran which shows no significant increase in free fatty acid content for at least 30–60 days. In the optimum process, 500 kg/hr of 12 - 13% moisture bran was extruded at 130°C and held 3 min at 97 - 99°C before cooling. Stabilized bran contained 6 - 7% moisture and was in the form of small flakes with 88% larger than 0.7 mm (25 mesh). Energy required to extrude the bran was 0.07 - 0.08 kW-hr/lcg bran, and wear on the extrusion surface indicated a life of 500 hr for the cone and 1000 - 2000 hr for other wearing parts.     

Interactions of Soluble Iron with Wheat Bran

Soft white and hard red wheat bran were found to contain 98.8 and 99.2% water insoluble iron, respectively. As the concentration of iron added to wheat bran was increased, less of the total added iron was bound. Ascorbic acid was found to inhibit binding of ferrous iron to wheat bran. It was found that boiling for 1 hr in a boiling water bath (BWB) had no effect on the destruction of phytic acid in wheat bran, whereas toasting for 1 hr at 178°C (350°F) and boiling for 1 hr in 1N HC1 had a significant effect.     

Dephytinization of wheat and rice brans by hydrothermal autoclaving process and the evaluation of consequences for dietary fiber content,antioxidant activity and phenolics

Autoclaving process applied to wheat and rice bran samples to decrease the phytic acid content and to enhance the functional and nutritional properties (dietary fiber and phenolic content, antioxidant activity) of bran samples. All hydrothermal treatments caused significant decreases in phytic acid contents of both wheat (95.2%) and rice bran (95.6%) samples. The most effective process conditions on enhancing the total dietary fiber content for both bran samples were pH 4.0 level and 1.5 h holding time. Autoclaving treatment resulted in a decrease in total phenolic contents after holding for 90 min and at 121 °C at their native pH levels. Autoclaving for 90 min caused the greatest degree of increment in the total antioxidant activity of wheat (12%, pH 4.0) and rice bran samples (2%, pH 3.5). Autoclaving treatment was found as quite effective method for both dephytinization and enrichment of wheat and rice brans as a functional food ingredient.Industrial relevanceAuthors believe that the study presents important new information in terms of both enhancing functional properties of wheat and rice brans by hydrothermally dephytinization treatment and revealing the correlation between hydrothermal treatment and functional ingredients of brans. In this way, proposed method transforms inexpensive and easily accessible sources into important food ingredients and gives them added value. Hydrothermal treatment also enables food industry to use cereal brans as functional ingredients in the applications of both designing and enriching new and healthy food formulations.     

Effect of Temperature and Fermentation Time on Phytic Acid and Polyphenol Content of Rabadi— A Fermented Pearl Millet Food

Rnbadi was prepared by fermenting a mixture of pearl millet flour and butter milk for three periods of time (3, 6 and 9 hr) at four temperatures (35°, 40°, 45° and 50°C). Temperature had little influence on degradation of either phytic acid or polyphenol content. At all temperatures the phytic acid and polyphenol content decreased with an increase in fermentation time. Nine hour fermentation resulted in maximum reduction of phytic acid (27–30%) as well as total polyphenols (1–12%) at all temperatures. Phytic acid was reduced to a greater extent than polyphenols.     

不同处理方法对米糠品质稳定性的影响

采用干热、湿热、微波和挤压法等4种方法处理新鲜米糠,比较不同方法对米糠过氧化物酶残留活力、水溶性蛋白质、植酸、维生素E和谷维素含量的影响,以及长期贮藏过程对米糠酸价和过氧化值的影响。研究结果表明:米糠经温度为130℃,含水量为30%,转速600r/min的挤压处理后,过氧化物酶残留活力为4.8%,维生素E、植酸和谷维素的含量分别为3.65%、0.35%、7.0%,但对水溶性蛋白质的含量影响较大。经过稳定化处理的米糠在贮藏过程中,米糠的酸价和过氧化值基本稳定,但原料米糠变化显著。     

Reduction in Phytic Acid Levels in Soybeans During Tempeh Production, Storage and Frying

Tempeh was prepared from Delmar variety soybeans inoculated with the traditional Indonesian inoculum (usar) and two pure culture strains of the mould Rhizopus oligosporus (BTU3K1 and CT11K2). The preparatory treatments during tempeh production decreased the phytic acid content (% dry weight) of soybeans, except for the fist soaking which significantly increased the phytic acid content. The phytic acid content of soaked soybeans was halved during tempeh fermentation and was further reduced when tempeh was stored for 72 hr at 5° and at 30°C. Deep fat frying of tempeh in peanut oil further halved the phytic acid content. Less than 10% of the phytic acid remained after tempeh fermentation, storage and frying.     

Amino Acid Composition and Some Antinutritional Factors of Cooked Faba Beans (Medammis): Effects of Cooking Temperature and Time

Easy-and hard-to-cook bean seeds were cooked by different heat treatments (100–125°C for 1–12 hr). Amino acid composition, tannins, phytic acid and trypsin inhibitor activity were determined. Almost all essential amino acids declined after cooking. Less than 10% of total tannins were decomposed during cooking, while up to 50% were leached to the cooking liquor. Retention of phytic acid in cooked beans was significantly lower than in cooked bean-liquor mixtures. Loss of phytic acid due to leaching was much higher for easy-to-cook beans than for hard-to-cook ones. Apparent retention of trypsin inhibitor activity amounted to about 50%. Optimum heat treatments were 125°C at 1 hr for easy and 120°C at 2 hr for hard-to-cook beans.     

The moisture content-equilibrium relative humidity relationship of rice bran at different temperatures

The moisture content/equilibrium relative humidity relationships at 15, 25 and 35°C, for unextracted rice brans from Burma and Tanzania, unextracted bran from a South African parboiled rice, and a pelleted extracted rice bran from India, are presented and discussed. The relationships differed in shape and position of the curves, and in the magnitude of hysteresis between adsorption and desorption. The equilibrium moisture contents at 65% r.h. and below, of Burmese, Tanzanian and Indian brans were in reverse order of their fibre and ash contents. These moisture contents did not decrease consistently with oil content as they did for those cereal grains and oil-seeds previously investigated. The hysteresis for the parboiled bran was less, and the equilibrium moisture content was generally lower than for the other brans.     

Effect of natural fermentation on nutritive value and in vitro protein digestibility of pearl millet

Two pearl millet cultivars: Composite Population III, obtained from the Department of Agronomy, Faculty of Agriculture, University of Khartoum and Baladi, obtained from El Obeid Research Station, were used in this study. Investigation showed that Composite Population III is of higher tannin, total polyphenols and phytic acid and lower in in vitro protein digestibility (IVPD), which was found to be 60.5%. The two cultivars were naturally fermented for 36 h at room temperature (30±2 °C) and pH, moisture content, protein, tannin, total polyphenols, phytic acid content and IVPD were determined at 4-h intervals. Fermentation was found to cause a significant reduction in total polyphenols and phytic acid content for the two cultivars. Fermentation for 36 h at room temperature was found to cause no changes in tannin content of fermented dough for the two millet cultivars.     

Protective effect of rutin against ultraviolet b-induced cyclooxygenase-2 expression in mouse epidermal cells

Rice bran was heated at 120°C for 0 to 30 min to extend the oxidative stability. Also, effects of visible light irradiation on the crude rice bran oil (RBO) from rice bran heated at 120°C for 20 min were studied. As heat treatment time increased from 0 to 30 min, rice bran had significantly high oxidative stability at 40°C for 12 days (p<0.05). Headspace oxygen content in rice bran without heat treatment decreased significantly (p<0.05) whereas those in heat treated rice bran did not change significantly (p>0.05). Results of acid value and conjugated dienoic acid (CDA) confirmed the higher oxidative stability of heat treated rice bran. γ-Oryzanol content was not significantly different among crude RBO during heat treatment and storage (p>0.05). Visible light irradiation caused similar degree of lipid oxidation in crude RBOs from rice bran irrespective of heat stabilization for 48 h, which may be due to the presence of photosensitizers in crude RBO like chlorophylls. This study showed that heat treatment was not effective to enhance the oxidative stability of RBO under visible light irradiation and products containing rice bran should be stored in the dark conditions.     

Influence of enzyme treatment of rice bran on gamma-aminobutyric acid synthesis by Lacto bacillus

Gamma-aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system. The production GABA from the cheaper glutamic acid is a valuable process. Rice bran is a potential source of glutamic acid decarboxylase which was therefore selected for production of gamma-aminobutyric acid (GABA) using lactic acid bacteria (Lactobacillus brevis (Lb.brevis) VTCC-B397). The influences of treatment of defatted rice bran with α-amylase, Alcalase (Al), Flavourzyme (Fl) and their combinations at different concentration ratios on the GABA synthesis were examined. With α-amylase impacts, concentration of GABA (6.41 mg mL⁻¹) was about 2.38 times higher than the control sample (2.69 mg mL⁻¹) under hydrolysis conditions of pH 6.5, temperature of 95 °C and α-amylase concentration of 0.15% (v/w) for 45 min. The α-amylase hydrolysis as prerequisite for protein hydrolysis using Al: Fl (ratio Al: Fl of 3: 7, concentration of 2% (w/w), pH = 8, temperature of 50 °C) reached the highest GABA synthesis efficiency, at 8.43 mg mL⁻¹. Results showed that the enzyme treatment positively affected the fermentation using Lb. brevis for GABA biosynthesis from defatted rice bran.     

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.     

响应面法优化脱脂米糠植酸提取工艺

利用响应面分析法优化了脱脂米糠中植酸的提取工艺条件,建立了植酸提取的二次多项式数学模型。在单因素试验基础上,选择pH、液料比、提取时间和提取温度为自变量,植酸得率和残渣蛋白质量为响应值,响应面优化得出最佳工艺条件为:pH3.9,液料比9∶1,提取时间4.4h,提取温度50℃。在最佳工艺条件下,植酸得率为5.27%,残渣蛋白质量为1.4034g(10g原料脱脂米糠)。在响应面优化工艺的基础上,选择了一浸一洗的浸提方式,并利用阴、阳离子交换树脂纯化了植酸粗溶液,浓缩得到了50%植酸溶液,植酸纯度为94.72%。     

Effect of soaking and phytase treatment on phytic acid,calcium, iron and zinc in rice fractions

With the aim to maximise phytic acid removal and minimise losses of dry matter and minerals (Ca, Fe, Zn) in rice, three products (whole kernels and flour milled from white and brown rice; and bran, all from the same batch of variety Kenjian 90-31) were soaked in demineralized water at 10 °C (SDW), NaAc buffer of pH 3.5 at 10 °C (SAB), and 500 U L⁻¹ phytase of pH 5.5 at 50 °C (SPS). In whole kernels and flour of white rice, phytic acid removal was 100% by all treatments; losses of dry matter, Ca, Fe, and Zn were 2–5%, 12–63%, 9–10%, and apparent gain of 63–72%, respectively. In whole brown rice, SAB removed 75% phytic acid, and SPS 100% from flour; dry matter, Ca, Fe, and Zn losses were 1–16%, 26–56%, 39–45%, and 23–24%. In rice bran, SPS removed 92% phytic acid, and SAB 50%; dry matter, Ca, Zn, and Fe losses were 20%, 48%, 63%, and apparent gain of 5%, respectively.     

Zinc and Phytate Distribution in Peas. Influence of Heat Treatment, Germination, pH, Substrate, and Phosphorus on Pea Phytate and Phytase

The largest proportions of zinc and phytate, 88.7 and 97.1%, respectively, were in the Garfield pea cotyledon; the greatest concentrations were in the germ. Cooking peas by two different methods resulted in 13% phytate reduction. Peas incubated 6.5 hr from 25 to 80°C yielded maximum phytate loss (25%) at 60°C due to phytase activated hydrolysis. Germination (10 d) decreased pea phytate 75% and increased phytase activity 12-fold. Semi-purified germinated pea phytase showed temperature optimum at 45°C, pH optimum of 5.2, 30% inhibition by 1 mM inorganic P, and substrate preference for pyrophosphate. Incubation of early germinated peas at optima pH and temperature is suggested for maximum phytate reduction.     

挤压膨化辅助提取米糠可溶性膳食纤维及其特性研究

以新鲜米糠为原料,在单因素和正交试验基础上,通过分析不同挤压工艺和酶解条件对米糠中可溶性膳食纤维提取率的影响,优化挤压膨化辅助酶水解技术提取可溶性膳食纤维。同时采用扫描电子显微镜、差示扫描热量法等表征可溶性膳食纤维的结构及物化特性。试验结果表明,在挤压温度130℃、螺杆速度200 r/min、物料含水量20%,酶用量2.0%、酶解温度75℃、酶解时间90 min、p H 6.0的条件下,可溶性膳食纤维提取率为30.35%。米糠可溶性膳食纤维表面形态疏松,呈蜂窝颗粒状,内部由纤维素类物质形成支撑主体,热力学相对稳定。与未经挤压膨化处理提取的可溶性膳食纤维相比,挤压辅助提取的可溶性膳食纤维具有更高的持水力、结合水力、溶胀力、结合脂肪能力及丰富的空间网状结构,结构及物化特性均得到明显改善。     

米糠中植酸磷的体外消化试验

试验采用体外消化的方法,借助植酸酶制剂将米糠中的植酸磷转化为无机磷,对植酸酶制剂的消化率作了初步测定,植酸磷的消化率可达60.3%;并对其最适pH值、适宜用量、适宜作用时间进行了探讨。     

DIELECTRIC PROPERTIES of RICE BRAN

The dielectric properties of rice bran have been of interest because of their correlation with moisture content and because to a large extent they determine the absorption of energy in dielectric heating applications. the dielectric properties, namely, dielectric constant, loss tangent, dielectric loss factor and a.c. conductivity of rice bran were measured experimentally at a frequency of 13.56 MHz by a resonance method using a Q-meter along with a coaxial, cylindrical sample holder. In order to study the effects of various factors, namely, the moisture content, temperature and bulk density of rice bran, the experiments were designed and performed based on Response Surface Methodology. the dielectric constant, dielectric loss factor and a.c. conductivity were found to have positive nonlinear relationships, while the loss tangent had a positive linear relationship within the ranges of factors studied, namely 3.95 to 14.05% (w.b.) moisture content, 26.5 to 53.5°C temperature, and 299.5 to 400.5 kg/m³ bulk density.