Enhancement of tofu isoflavone recovery by pretreatment of soy milk with koji enzyme extract

Isoflavones are novel nutraceutical constituents of soybeans, but considerable amounts are lost in the whey during conventional tofu manufacturing. In this study, in a small-scale process, 2 mL of koji enzyme extract (soybean koji/deionized water, 1/3, w/v) was combined with 600 mL of soy milk, and 30 mL aliquots were incubated at 35 degrees C for 0, 30, 60, 120, and 300 min, for enzyme pretreatment. After each treatment time, soy milk was heated to 85 degrees C, CaSO4 was added to aggregate protein, and the mixture was centrifuged to separate the solids (tofu) from the whey. The tofu yield and moisture contents from soy milk treated for 30 or 60 min were higher than those from soy milk treated for 0 (control), 120, or 300 min. The protein content of freeze-dried tofu varied in a limited range, and native PAGE and SDS-PAGE patterns revealed slight quantitative and qualitative variations among products. Soy milk daidzein and genistein contents increased while daidzin and genistin contents decreased as the time of enzyme pretreatment of the soy milk increased. After 30 min of pretreatment, daidzin, genistin, daidzein, and genistein contents recovered in tofu products were higher than those of the control. In a pilot-scale process, aliquots (3 L) of soy milk were enzyme-treated for 30 min, aggregated with CaSO4, and hydraulically pressed to remove the whey. As in pretreatments, soy milk daidzein and genistein contents increased while daidzin and genistin contents decreased. In a comparison of the control and enzyme-treated tofu products, the total recoveries of daidzin, genistin, daidzein, and genistein in the tofu products increased from 54.9% to 64.2%. When the tofu products were subjected to a sensory panel test, both products were judged acceptable.     

Rheological properties and sensory characteristics of set-type soy yogurt

The study examined chemical composition and rheological and sensory properties of probiotic soy yogurt during 28 day storage at 4 degrees C. Soymilk supplemented with 2% (w/v) inulin or 1% (w/v) each of raffinose and glucose was used as a base for soy yogurt manufacture. Viability of probiotic organisms and their metabolic activity measured as production of organic acids and aldehyde content responsible for beany flavor, as well as rheological and sensory properties of soy yogurt, were examined. Inulin or raffinose/glucose supplementation in soymilk increased the bacterial population by one log cycle and the amount of lactic acid. Probiotic bacteria metabolized more aldehyde than yogurt culture and substantially reduced the beaniness in soy yogurt as determined by sensory evaluation. The probiotic soy yogurts showed more viscous and pseudoplastic properties than the control soy yogurts, but the sensory evaluation results showed preference for the control soy yogurts which were slightly less viscous. Control soy yogurt provided better mouth feel than probiotic soy yogurts.     

Effect of water content on thermal behavior of freeze-dried soy whey and their isolated proteins

Thermal behavior of lyophilized soy whey (LSW) and whey soy proteins (WSP) at different water contents (WC) was studied by DSC. In anhydrous condition, Kunitz trypsin inhibitor (KTI) and lectin (L) were more heat stable for WSP with respect to LSW sample. The increase of WC destabilized both proteins but differently depending on the sample analyzed. Thermal stability inversion of KTI and L was observed for WSP and LSW at 50.0% and 17.0% WC, respectively, which correspond to the same water-protein content mass ratio (W/P ≈ 1.9). At W/P < 1.9, KTI was more heat stable than L. Before the inversion point, WC strongly modified the peak temperatures (T(p)) of KTI and L for WSP, whereas this behavior was not observed for LSW. The high sugar content was responsible for the thermal behavior of KTI and L in LSW under anhydrous condition and low WC. These results have important implications for the soy whey processing and inactivation of antinutritional factors.     

Isoflavone profile and biological activity of soy bread

The present study examines the ability of isoflavone extracts from whole soy bread and two soy bread fractions, crumb and crust, to modulate the proliferation of human prostate cancer PC-3 cells. Total isoflavone content in the two fractions of soy bread were similar (3.17 micromol/g dry basis). However, their conjugate patterns were altered. Both fractions of soy bread contained a similar level of isoflavone aglycones ( approximately 24%). Low concentrations of soy bread extracts increased PC-3 cell proliferation as much as 47% compared to untreated control. This proliferative effect in cell growth was reduced at higher extract concentration. Soy bread crust extract (10 mg/mL) reduced PC-3 cell proliferation by 15% compared to untreated control. Interestingly, wheat bread extracts increased cell proliferation at all concentrations tested. Although extracts from both breads possessed biological activity, only soy bread crust extract reduced PC-3 cell proliferation. This observation may be related to the presence of soy in this bread.     

Enzymatic degradation of oligosaccharides in pinto bean flour

The use of dry edible beans is limited due to the presence of flatulence factors, the raffinose oligosaccharides. Our objective was to investigate the process for the removal of oligosaccharides from pinto bean using enzymatic treatment and to compare it to removal by soaking and cooking methods. Crude enzyme preparation was produced by six fungal species on wheat bran- and okara-based substrates with soy tofu whey. The loss of raffinose oligosaccharides after soaking pinto beans for 16 h at the room temperature was 10%, after cooking for 90 min was 52%, and after autoclaving for 30 min was 58%. On the other hand, the treatment using crude alpha-galactosidase (60 U mL(-1)) produced by Aspergillus awamori NRRL 4869 from wheat bran-based substrate with soy tofu whey on pinto bean flour for 2 h completely hydrolyzed raffinose oligosaccharides. These results supported that the enzymatic treatment was the most effective among various processing methods tested for removing the raffinose oligosaccharides, and hence, crude alpha-galactosidases from fungi have potential use in the food industry.     

~(60)Coγ射线诱变阿维拉霉素筛选高产菌株及培养基优化

用60Coγ射线对绿色产色链霉菌A-05菌株进行了诱变处理,以正突变率为标准确定诱变的适宜剂量为350 Gy。诱变后得到5株较高产突变菌株,其中H-15菌株经连续传代6次,遗传性状稳定,阿维拉霉素发酵单位达到68.5mg/L。采用响应面分析法对菌株H-15生产阿维拉霉素的发酵培养基碳氮源进行了优化设计。在所试验的碳氮源中,可溶性淀粉、核糖分别作为唯一碳源时,阿维拉霉素发酵单位较高,分别达82.67和79.45mg/L,乳糖、果糖、葡萄糖分别作为唯一碳源时菌株的效价较低;3%的豆粕粉和2%的大豆蛋白胨作为氮源时阿维拉霉素发酵单位分别为77.6和62.7mg/L。采用双碳源双氮源更有利于菌株提高阿维拉霉素的发酵单位,响应面分析结果表明,可溶性淀粉、核糖和大豆蛋白胨对阿维拉霉素发酵单位影响较显著。优化后的碳氮源组成为:可溶性淀粉20.12g/L,D-核糖7.81g/L,豆粕粉25.23g/L,大豆蛋白胨5.06g/L。优化后的模型计算出阿维拉霉素发酵单位由原来的71.63mg/L提高到101.48mg/L。     

Effects of caseins on thermal stability of bovine beta-lactoglobulin

Casein fractions have been shown to act as molecular chaperones and inhibit aggregation of whey proteins in dilute solutions (< or =1% w/v). We evaluated if this approach would stabilize protein solutions at higher concentration and thermal processing temperatures desired for beverage applications. Mixtures of beta-lactoglobulin (BLG) (6% w/v) with either beta-casein (BCN) (0.01-2% w/v) or alpha s-casein (ACN) (2% w/v) were adjusted to pH 6.0 and heated (70-90 degrees C) for 20 min, cooled, and then analyzed to determine the degree of aggregation. Aggregation was determined by solution turbidity as optical density (OD) at 400 or 600 nm. The addition of 0.05% (w/v) BCN or greater caused a drop in turbidity for solutions heated at 70-90 degrees C. In contrast, inhibition was observed in BLG-ACN mixtures at 70 degrees C but not at > or =75 degrees C. Moreover, prolonged heating (90 min) of BLG with 2% (w/v) BCN (pH 6.0) at 90 degrees C produced a clear solution while BLG-ACN solutions formed translucent gels after heating for 15 min. The weight-averaged molar mass and root-mean-square (rms) radius of soluble aggregates were determined by size exclusion chromatography in conjunction with multiangle laser light scattering (SEC-MALS). SEC-MALS confirmed the turbidity results by showing that the BLG-BCN mixture (8% w/v protein) produced aggregates with lower molar mass and smaller rms radius (majority 20-40 nm). These results showed that BCN is a feasible component to stabilize higher concentrations of whey proteins in beverages.     

Rheology and stability of acidified food emulsions treated with high pressure

The stability and rheology of acidified model oil-in-water emulsions (pH 3.6 +/- 0.1) were evaluated before and after high-pressure treatments. Varying concentrations of canola oil (0-50% w/w), whey protein isolate, polysorbate 60, soy lecithin (0.1-1.5% w/w each), and xanthan (0.0-0.2% w/w) were chosen. Exposure to high pressures (up to 800 MPa for 5 min at 30 degrees C) did not significantly affect the equivalent surface mean diameter D[3,2], flow behavior, and viscoelasticity of the whey protein isolate and polysorbate 60-stabilized emulsions. Pressure treatments had negligible effects on emulsion stability in these systems, except when xanthan (0.2% w/w) was present in which pressure improved the stability of polysorbate 60-stabilized emulsions. Soy lecithin-stabilized emulsions had larger mean particles sizes and lower emulsion volume indices than the others, indicating potential instability, and application of pressure further destabilized these emulsions.     

Isolation and analysis of kappa-casein glycomacropeptide from goat sweet whey

Glycomacropeptide (GMP) was purified from goat sweet whey by anion-exchange and hydrophobic interaction chromatography. Approximately 0.06% (w/v) of sweet whey was recovered as GMP. Amino acid analysis of the GMP preparation showed that the content of phenylalanine (an amino acid that does not occur in goat GMP) was negligible, indicating that the GMP was of high purity. The goat GMP contained 25 microg sialic acid per mg of dry weight. This was approximately 3-fold lower than the sialic acid concentration in bovine GMP reported in the literature. Gel electrophoretic results demonstrated that most of the goat GMP occurs as a dimer. The GMP was intensely stained with Coomassie blue in 50% methanol containing 12.5% (w/v) trichloroacetic acid, but showed very weak metachromasia with the same dye in 45% methanol containing 10% acetic acid, a preparation commonly used to stain protein.     

Effect of partial replacement of gum arabic with carbohydrates on its microencapsulation properties.

Gum arabic solutions (10% w/v) were emulsified with soy oil at oil/gum ratios of 0.25-5.0. At oil/gum ratios <1.0, it was established that gum arabic could be partially replaced with a nonsurfactant carbohydrate. To assess different carbohydrates as replacers for gum arabic, emulsions and spray-dried emulsions of soy oil and mixed solutions (10% w/v) of gum arabic and a range of carbohydrate wall materials (oil/gum = 0.5) were prepared and analyzed. Maize starch and glucose were ineffective as partial replacers of gum arabic, but maltodextrins of various dextrose equivalence values (5.5-38) successfully replaced 50% of the gum arabic. The microencapsulation efficiency of the gum arabic/maltodextrin stabilized powders was further increased by increasing total solids of the feed to the dryer and by increasing the atomizer nozzle diameter.     

春兰离体根状茎生长和分化的研究

为优化春兰离体培养条件,以春兰（Cymbidium goeringii）芽诱导的离体根状茎为试材,研究了植物生长调节剂NAA和BA以及有机添加物马铃薯匀浆、番茄匀浆、香蕉泥、蛋白胨和酵母提取物对根状茎生长和新芽增殖的影响。结果表明：从根状茎诱导丛生芽的适宜培养基为1/2MS+0.1mg/LBA+0.5mg/LNAA+1.5g/LAC（活性炭）;根状茎增殖的适宜培养基为1/2MS+0.1mg/LBA+5.0mg/LNAA+1.5g/LAC;除香蕉泥外,其他有机添加物对根状茎生长和增殖均有不同程度的促进作用,但以蛋白胨的效果最佳。     

Influence of different dietary doses of n-3- or n-6-rich vegetable fats and alpha-tocopheryl acetate supplementation on raw and cooked rabbit meat composition and oxidative stability

This study evaluates the effects of replacing beef tallow added to rabbit feeds (3% w/w) by different doses (0%, 1.5% and 3% w/w) of n-6- or n-3-rich vegetable fat sources (sunflower and linseed oil, respectively) and alpha-tocopheryl acetate supplementation (0 and 100 mg/kg) on the fatty acid composition, alpha-tocopherol content, and oxidation levels [assessed by analyzing thiobarbituric acid (TBA) and lipid hydroperoxide values] in rabbit meat. We also measured these parameters after cooking and refrigerated storage of cooked rabbit meat. Both dietary alpha-tocopheryl acetate supplementation and the dose and source of fat added to feeds influenced meat fatty acid composition, modifying the n-6/n-3 ratio, which was more nutritionally favorable when linseed oil was used. Furthermore, the addition of linseed oil and the supplementation with alpha-tocopheryl acetate enhanced long-chain PUFA biosynthesis. However, the addition of 3% linseed oil increased meat oxidation, and although it was reduced by dietary supplementation with alpha-tocopheryl acetate in raw meat, this reduction was not as effective after cooking. Therefore, dietary supplementation with 1.5% linseed oil plus 1.5% beef tallow and with alpha-tocopheryl acetate would be recommended to improve the nutritional quality of rabbit meat.     

Inhibition of lipid peroxidation by Lactobacillus acidophilus and Bifidobacterium longum.

The inhibition of lipid peroxidation by Lactobacillus acidophilus and Bifidobacterium longum was investigated using two lipid model systems. All eight strains, including six strains of L. acidophilus and two strains of B. longum, demonstrated an inhibitory effect on linoleic acid peroxidation. The inhibitory rates on linoleic acid peroxidation ranged from 33 to 46% when 1 mL of intracellular cell-free extract was tested. In the second model system, the cell membrane of osteoblast was used as the source for biological lipid. The results indicated that all strains were able to protect biological lipids from oxidation. The inhibition rates on cell membrane lipid peroxidation ranged from 22 to 37%. The effect of L. acidophilus and B. longum on inhibition of fluorescent tissue pigment accumulation was also obtained for osteoblastic cells. The inhibition rates on fluorescent tissue pigment accumulation ranged from 20 to 39%. The antioxidative effect of each milliliter of intracellular cell-free extract of L. acidophilus and B. longum was equivalent to 104-172 ppm of butylated hydroxytoluene (BHT). These results indicated that all strains demonstrated high antioxidative activity. The scavenging ability of lipid peroxidation products, tert-butyl hydroperoxide and malondialdehyde, was also evaluated. The results showed that L. acidophilus and B. longum were not able to scavenge the tert-butyl hydroperoxide. Nevertheless, malondialdehyde was scavenged well by these strains.     

Heat-induced soy-whey proteins interactions: formation of soluble and insoluble protein complexes

The aggregation behavior during heating of a solution containing soy protein and whey protein isolate (WPI) was studied using rheology, confocal microscopy, gel filtration, and electrophoresis. Soy/WPI mixtures formed gels at 6% total protein concentration with a high elastic modulus (G') and no apparent phase separation. The ratio of soy to WPI was fundamental in determining the type of network formed. Systems containing a high soy to WPI ratio (>70% soy protein) showed a different evolution of the elastic modulus during heat treatment, with two apparent stages of network development. Whey proteins formed disulfide bridges with soy proteins during heating, and at low ratios of soy/WPI, the aggregates seemed to be predominantly formed by 7S, the basic subunits of 11S and beta-lactoglobulin. Size exclusion chromatography indicated the presence of high molecular weight soluble complexes in mixtures containing high soy/WPI ratios. Results presented are the first evidence of interactions between soy proteins and whey proteins and show the potential for the creation of a new group of functional ingredients.     

Efficiency and protective effect of encapsulation of milk immunoglobulin G in multiple emulsion

Milk immunoglobulin G (IgG), separated with protein G affinity chromatography, and IgG in colostral whey were encapsulated by 0.5% (w/v) of Tween 80, sucrose stearate, or soy protein, which were used as secondary emulsifiers in the water in oil in water type multiple emulsion. The residual contents of separated IgG and IgG in colostral whey, ranging from 58.7 to 49.7% and from 13.2 to 21.3%, respectively, in the inner water phase (water phase surrounded by oil phase) with emulsifiers were determined by ELISA. However, the emulsion stability decreased after 24 h, and the residual IgG content in the inner water phase was lowered. Encapsulation of IgG in the multiple emulsion increased the stability of separated IgG against acid (pH 2.0) and alkali (pH 12.0) by 21-56% and 33-62%, respectively, depending on the emulsifier used. Moreover, multiple emulsion also provided a remarkable protective effect on separated IgG stability against proteases. The residual contents of separated IgG in multiple emulsion, using Tween 80 as secondary emulsifier, incubated for 2 h with pepsin (pH 2.0) and trypsin and chymotrypsin (pH 7.6) (enzyme/substrate = 1/20) were 35.4, 72.5, and 82.3%, whereas those of separated IgG in enzyme solution were only 7.2, 33. 1, and 35.2%, respectively. However, the separated IgG loss during the preparation of multiple emulsion was almost 41-50%.     

Antimicrobial and antioxidant effects of milk protein-based film containing essential oils for the preservation of whole beef muscle

Milk protein-based edible films containing 1.0% (w/v) oregano, 1.0% (w/v) pimento, or 1.0% oregano-pimento (1:1) essential oils mix were applied on beef muscle slices to control the growth of pathogenic bacteria and increase the shelf life during storage at 4 degrees C. Meat and film were periodically tested during 7 days for microbial and biochemical analysis. The lipid oxidation potential of meat was evaluated by the determination of thiobarbituric reactive substances (TBARS). The availability of phenolic compounds from essential oils was evaluated by the determination of total phenolic compounds present in the films during storage. Antioxidant properties of films during storage were also evaluated following a modified procedure of the N,N-diethyl-p-phenylenediamine colorimetric method. Oregano-based films stabilized lipid oxidation in beef muscle samples, whereas pimento-based films presented the highest antioxidant activity. The application of bioactive films on meat surfaces containing 10(3) colony-forming units/cm2 of Escherichia coli O157:H7 or Pseudomonas spp. showed that film containing oregano was the most effective against both bacteria, whereas film containing pimento oils seems to be the least effective against these two bacteria. A 0.95 log reduction of Pseudomonas spp. level, as compared to samples without film, was observed at the end of storage in the presence of films containing oregano extracts. A 1.12 log reduction of E. coli O157:H7 level was noted in samples coated with oregano-based films.     

不同浓度牛蒡提取液对菠菜生长及品质的影响

通过盆栽试验,研究了不同浓度牛蒡提取液对菠菜生长及品质的影响.结果表明,与清水对照相比,喷施30～1500 mg/L牛蒡提取液可使菠菜鲜重增加10.8%～30.0%;可能由于"稀释效应",叶绿素含量降低2.7%～15.7%;Vc含量提高46.1%～136.4%;硝酸盐含量降低 23.2%～69.2%;草酸含量降低 22.3% ～67.6%.其中,对叶绿素含量、Vc 含量、硝酸盐及草酸含量的效应,都以 30 mg/L 处理的效果最好.而鲜重方面,30 mg/L处理与效果最好的 500 mg/L处理之间差异亦不显著.因此,从对菠菜的生长情况、品质情况及经济角度综合考虑,牛蒡提取液应用在菠菜上的适宜浓度为 30 mg/L.     

Potato peel extract-a natural antioxidant for retarding lipid peroxidation in radiation processed lamb meat

The effective utilization of potato peel, a waste generated in large quantities by the food industry, as an antioxidant was investigated. Potato peel extract (PPE) exhibited high phenolic content (70.82 mg of catechin equivalent/100 g), chlorogenic acid (27.56 mg/100 g of sample) being the major component. The yield of total phenolics and chlorogenic acid increased by 26 and 60%, respectively, when the extract was prepared from gamma irradiated (150 Gy) potatoes. PPE showed excellent antioxidant activity as determined by beta-carotene bleaching and radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH). The suitability of PPE for controlling lipid oxidation of radiation processed lamb meat was also investigated. PPE (0.04%) when added to meat before radiation processing was found to retard lipid peroxidation of irradiated meat as measured by TBA number and carbonyl content. The antioxidant activity of PPE was found to be comparable to butylated hydroxytoluene (BHT).     

不同养分管理措施下常年菜地蔬菜生长及氮素径流特征

【目的】蔬菜生产超量施肥现象十分普遍,由此导致的面源污染问题日益严重。研究探讨常年菜地的合理施肥技术,明确蔬菜合理的氮肥投入阈值范围,从污染源头控制氮的迁移、流失,对于降低氮肥对水体的污染风险具有积极意义。【方法】本试验采用大田小区试验方法,设置不施肥对照和不同用量化肥配施有机肥处理(N0,化肥氮空白;CON,习惯施肥;OPT,优化施肥;OPT+N,优化增氮;OPT+P,优化增磷;OPT+NPK,优化增氮磷钾),研究了不同养分管理措施对常年菜地甘蓝—茄子—甘蓝轮作模式下蔬菜生长及氮素径流流失的影响。【结果】连续三茬、为期一年的蔬菜试验,共采集径流样品18次。整个试验期间,不同处理的菜地地表径流铵态氮浓度均低于2.0mg/L的地表水V类水标准限值,且施肥对铵态氮的影响无明显规律性。地表径流硝态氮和总氮具有相似的浓度变化特征,浓度范围分别为0.03 28.43 mg/L和1.06 31.79 mg/L,硝态氮是土壤矿质氮流失的主要氮素形态。施氮不同程度增加总氮和硝态氮浓度,且化肥氮的作用尤为明显。几乎所有径流样品的总氮浓度均超过2.0 mg/L的地表水V类水的标准限值,OPT+NPK处理总氮浓度及硝态氮超标率均最高。对照处理的菜地总氮年流失负荷为30.8 kg/hm2,化肥氮空白处理与对照间无显著差异。其他有机无机肥配施处理中CON、OPT、OPT+N、OPT+P和OPT+NPK处理总氮年流失负荷分别为69.81、54.95、76.6、55.45和90.73 kg/hm2,分别较对照显著提高126.51%、78.29%、148.54%、79.92%和194.39%,且以OPT+NPK处理的流失负荷(90.73 kg/hm2)最高、OPT处理负荷较低(54.95 kg/hm2)。菜地施肥处理的氮肥流失系数在1.47%3.44%之间,总体随化肥氮用量增加而升高。施肥显著增加蔬菜产量,化肥氮空白处理的甘蓝和茄子产量较相应对照处理分别增加67.50%和114.20%,其他有机无机肥配施处理下两种蔬菜产量的增幅分别为5.1 5.5倍和4.5 5.9倍。相同有机肥用量条件下,施用氮、磷、钾化肥对蔬菜的增产作用明显,且以氮、磷、钾肥用量均最高的OPT+NPK处理的蔬菜产量增幅最大。【结论】从兼顾经济效益和环境效益角度出发,综合分析蔬菜产量、肥料投入成本及总氮流失负荷,优化施肥(OPT)处理可作为常年菜地推荐施肥技术方案。     

Effects of manure-based urea pellets on growth,yield, and nitrate content in coriander,garden cress,and parsley plants

Various organic residues and animal manures represent an excellent matrix material for production of natural-based pellet fertilizers. Fully decomposed cow manure with 50% w/w urea was used for pellet production in densities of 400 or 800 kg/m³, representing low and high compact urea pellets. The growth of coriander (Coriandrum sativum L.), garden cress (Lepidium sativum L.), and parsley (Petroselinum crispum Mill.) were then evaluated under application of these pelleted urea compared to urea alone and unfertilized plants. The total amount of applied nitrogen (N) in the form of urea or pelleted urea was 300 mg/kg soil, wherein pelleted urea treatments, 30% of N was incorporated into the soil as urea alone before planting. The results showed that application of pelleted urea in low and high compactness resulted in different plant responses in the three vegetable crops. Plant growth and biomass production was increased in plants treated with urea or low compact urea pellets. Leaf N concentration and the Soil-Plant Analysis Development (SPAD) index were increased by low but not by high compact urea pellet application. Regardless of compactness, pellet treated plants had less nitrate content compared to urea treated plants. Number of flowering plants in coriander and garden cress was higher with high compact urea pellet and in unfertilized plants, whereas plants treated with urea or with low compact urea pellet showed fewer flowering plants. So, for production of these leafy vegetables low compact pellet is preferred.