Dephosphorylation of Phytic Acid in Rice Bran

Incubation time and temperature, moisture content, and pH were examined to determine the conditions necessary for the hydrolysis of phytic acid in rice bran. The extent of hydrolysis increased with increase in moisture content, and autoclaving for 1 hr at 121°C destroyed a significant proportion of the phytic acid at high moisture contents. Maximum hydrolysis of phytic acid occurred by heating at pH 4.5. Incubation of rice bran slurry for 24 hr at 55°C, pH 5.1 reduced the phytic acid level by approximately 80%.     

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。     

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.     

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.     

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.     

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.     

Autolysis of phytic acid and protein in canola meal (Brassica spp.), wheat bran (Triticum spp.) and fish silage blends

Fish silage, canola meal, and wheat bran were blended to form an acid-stabilised, paste-like product. Changes in protein nitrogen, non-protein nitrogen, phytic acid, and orthophosphorus contents of the acidified blends were measured over a 5-week period of storage at room temperature (20–22°C). During the storage period, phytic acid from the canola meal was dephosphorylated by phytase from the wheat bran. Changes in the level of non-protein nitrogen showed that the fish proteins were partially hydrolysed and liquefied during storage, and that the fish enzymes may have partially hydrolysed the canola meal and wheat bran proteins. The resulting product could be stored at room temperature without spoiling and could be dried in conventional drying equipment. This process provides a means of improving the nutritional value of canola meal by reducing its high phytate content, and of producing a homogeneous dry feed commodity from liquid fish silage.     

Physico-Chemical Characteristics of Rice Bran Processed by Dry Heating and Extrusion Cooking

Abstract

Rice bran was stabilized by dry heat and extrusion cooking method. Physico-chemical, functional, and storage characteristics of stabilized rice bran were evaluated. The rice bran stabilization affected its crude fat and crude ash contents significantly, whereas the other constituents remained almost unchanged. The content of reducing, nonreducing, and total sugars remained unaffected and did not differ significantly from raw rice bran. The neutral detergent fiber (NDF) contents of raw and dry-heat treated rice bran did not differ significantly. However, after extrusion stabilization, the NDF increased significantly. Similar effects were observed in composition of gum fiber and total fiber. The stabilization of rice bran had a significant reduction in lysine and phytic acid content. Bulk density and water absorption were higher in extruded stabilized rice bran than dry-heat treated bran. Protein solubility was maximum in raw bran, whereas damaged starch content was higher in stabilized bran. Color of the extruded bran was dark brown, whereas that of dry-heat stabilized was light brown. It was observed that dry-heat treated bran was stored up to 30 days, whereas extruded bran was stored up to 60 days without any changes in the free fatty acid content.     

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.     

Preparation and characterization of high‐quality rice bran proteins

Rice bran contains 120–200 g kg^?1 protein in addition to a large amount of fat, carbohydrate, and phytic acid. Rice bran protein (RBP) fractions were refined by a two‐step preparation to eliminate residual carbohydrate. The first step involved the sequential extraction of defatted rice bran into RBP fractions using their distinct solubility to give 37 g kg^?1 of albumin, 31 g kg^?1 of globulin, 27 g kg^?1 of glutelin, and 2 g kg^?1 of prolamin. In the second step, carried out by dissolving in respective solvent and isoelectric precipitation, the protein content of each fraction increased from 69% to 97% for albumin, from 71% to 90% for globulin, from 74% to 83% for glutelin, and from 18% to 20% for prolamin. The low protein content in the prolamin fraction might be due to its low solubility in the protein assay. Emulsifying stability index and surface hydrophobicity increased in the second‐step preparation of albumin and globulin, but not of glutelin. Emulsifying properties of RBPs were lower than that of a soybean protein isolate. Denaturation temperatures and enthalpy values of denaturation for albumin, globulin, glutelin, and prolamin were 50.1 °C/1.2 J g^?1, 79.0 °C/1.8 J g^?1, 74.5 °C/3.0 J g^?1, and 78.5 °C/8.1 J g^?1, respectively. No significant differences in the denaturation temperatures and enthalpy values of denaturation of RBP fractions were obtained with these two‐step preparations (P < 0.05). Copyright © 2007 Society of Chemical Industry     

Release of phenolic acids from defatted rice bran by subcritical water treatment

BACKGROUND: Oil production from rice bran, an undervalued by‐product of rice milling, produces defatted rice bran (DRB) as a waste material. Although it is considered a less valuable product, DRB still contains useful substances such as phenolic compounds with antioxidant, UV‐B‐protecting and anti‐tumour activities. In this study the phenolic acids in DRB were extracted with subcritical water at temperatures of 125, 150, 175 and 200 °C. RESULTS: Analysis of total phenolics using Folin–Ciocalteu reagent showed about 2–20 g gallic acid equivalent kg^?1 bran in the extracts. High‐performance liquid chromatography analysis showed low contents of phenolic acids (about 0.4–2 g kg^?1 bran). Ferulic, p‐coumaric, gallic and caffeic acids were the major phenolic acids identified in the extracts. Thermal analysis of the phenolic acids was also done. The thermogravimetric curves showed that p‐coumaric, caffeic and ferulic acids started to decompose at about 170 °C, while gallic acid did not start to decompose until about 200 °C. CONCLUSION: Subcritical water can be used to hydrolyse rice bran and release phenolic compounds, but the high temperatures used in the extraction can also cause the decomposition of phenolic acids. Copyright © 2010 Society of Chemical Industry     

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.     

可食用脱脂米糠的制备

通过皂化脱脂与水洗法结合,去除脱脂米糠中的不可食用部分,并采用物理粉碎和酶技术相结合对米糠纤维进行改性。最终产品中含灰分2.4%、蛋白质34.8%、脂肪0.5%、粗纤维22.2%、碳水化合物35.1%;有机溶剂残留量从原料的37.22μg/g降至产品的1.97μg/g;90%～92%的颗粒的粒径在20μm以下,超过人体舌头分辨颗粒物的极限,最大不超过27μm,得到一种高蛋白、高纤维、低脂肪的可食用脱脂米糠食品。     

Nutritional quality of extruded snacks developed from composite of rice brokens and wheat bran

Wheat bran was mixed with broken rice to develop nutritionally balanced extruded crisp snacks for human consumption. The inclusion of wheat bran enhanced the content of nutrients such as calcium, phosphorus, iron, copper, thiamine, riboflavin, lysine and also of antinutrients like phytic phosphorus and trypsin inhibitor. Extrusion cooking decreased the content of thiamine, riboflavin and lysine. The degradation of phytic phosphorus and inactivation of trypsin inhibitor had an improving effect on the nutritional quality of the extruded snacks as reflected by higher in vitro digestibility of its proteins.     

Extraction Technique and Characteristics of Soluble Protein in Germinated Brown Rice

Effects of germination methods and extraction conditions on soluble protein yield in brown rice were investigated. Extraction temperature and solid to solvent ratio were significant factors. Highest soluble protein yields were obtained from germinated brown rice at 41.5°C for 2 h using a solid to solvent ratio of 1:10 at pH 8.5. This was about 20% higher than that from non-germinated brown rice. Characteristics of the extracted protein from germinated rice indicated an improved solubility, a lower isoeletric point, a reduction in high molecular weight components and an increase in small peptides compared to non-germinated rice.     

Optimization of Extrusion Rice Bran Stabilization Process

Effects of processing variables, production rate, number of die openings and initial moisture content on the discharge temperature and power input during rice bran extrusion with an autogenous single-screw extruder were analyzed. At extrusion temperatures above 128°C, all lipase activity in the bran was lost regardless of moisture content of the bran fed. Net specific energy input (NSE) varied with changes in die opening and moisture contents and total power efficiency was increased with increasing production rate without change in NSE value. Percolation rate through the extruded bran bed was increased to nine times over that of raw bran; the extraction time to reach 1% residual oil in extruded bran was reduced to 10 min from 100 min for the raw bran.     

Fermentation of rice-bengal gram dhal blends with whey: Changes in phytic acid content and in vitro digestibility of starch and protein

Whey fermentation of various rice and bengal gram dhal blends prepared by mixing them in different proportions at 35 °C for 18 h brought about a significant decline in phytic acid content. Phytic acid content in various blends decreased to the extent of 23 to 36 per cent over the control values. Whey incorporation as well as fermentation improved the starch and protein digestibility (in vitro) of all the rice-bengal gram dhal mixtures. Improvement in starch and protein digestibility is related to the reduction in phytic acid content, as this antinutrient is known to inhibit amylolysis and proteolysis. A significant negative correlation found between phytic acid and digestibility of starch and protein strengthens our findings.     

不同加工方式对米糠粉食品配料理化特性的影响

为了改善米糠的理化特性,开发新型米糠食品配料,本文研究了挤压膨化、微波蒸煮和高温焙炒三种整体加工方式对脱脂米糠理化特性的影响。结果表明,脱脂米糠经过三种整体加工方式处理后,理化特性均得到改善,其中挤压膨化米糠具有最高的水溶性指数、吸水性指数、糊化度及分散稳定性。与未处理组相比,挤压膨化米糠水溶性指数、吸水性指数和糊化度分别提高了4.82%、18.92%和96.04%。同时,三种整体加工方式显著减少了米糠中还原糖和植酸的含量,而分析米糠的酚类物质和抗氧化活性时,发现高温焙炒显著增加了脱脂米糠中总酚含量及抗氧化能力,但挤压膨化降低了脱脂米糠中总酚含量和抗氧化能力。本研究可以为脱脂米糠作为糊粉类营养代餐食品配料的加工提供指导。     

Purification and characterisation of antioxidative peptides from unfractionated rice bran protein hydrolysates

Crude rice bran protein (CRBP) was prepared by alkaline extraction and then treated with 0.6 m HCl to remove phytic acid. The phytate‐free rice bran protein (PFRBP) was hydrolysed with proteases M, N, S, P and pepsin under optimal conditions. Hydrolysates obtained from various hydrolysis periods were subjected to analysis for their degree of hydrolysis (DH) and functional properties. The hydrolysates were fractionated by reversed‐phase column chromatography on Kaseigel ODS resin (120–140 μm) using a stepwise gradient of aqueous ethanol, and their activities were measured. The 40% ethanol fraction of protease P 4 h‐hydrolysate was separated by successive reversed‐phase high‐performance liquid chromatography and the amino acid sequences of isolated antioxidative peptides were determined by a protein sequencer and matrix‐assisted laser desorption ionisation‐time of flight mass spectrometry. Crude rice bran protein had higher antioxidative activity than PFRBP, due to the presence of phytic acid. Phytate contents of rice bran, CRBP and PFRBP were 2.5%, 1.42% and 0%, respectively. The activity of PFRBP increased upon protease digestion. Protease M hydrolysates showed the highest DH, but the lowest antioxidative activity. Hydrolysates with DH below 10% had higher antioxidative activity than those above 20%. This result indicates that the antioxidative activity of the hydrolysates is inherent to their characteristics amino acid sequences of peptides depending on the protease specificities.     

利用弱碱性阴离子交换树脂从脱脂米糠中制取植酸的研究

以脱脂米糠为原料,通过酸浸、离子交换吸附、洗脱、精制、浓缩过程利用D318型弱碱性阴离子交换树脂制得植酸。试验结果表明,D318型阴离子交换树脂从脱脂米糠植酸粗溶液中吸脱植酸的最佳工艺条件为:吸附液浓度为10 mg/ml,吸附液流速为1.0 ml/min,NaOH洗脱液的流速为2.0 ml/min,NaOH洗脱液浓度为1.5 mol/L,操作温度为45℃,pH值为2.5左右。