The Enhancement of Polygalacturonase and Polymethylgalacturonase Production on Solid-State Conditions by Aspergillus foetidus

In this study, a previously isolated strain of Aspergillus foetidu s Ege-K-635 producing highly active polygalacturonase and polymethylgalacturonase was used for improvement of enzyme production using solid-state conditions. To enhance the enzyme yield, the mixture of two substrates such as sugar beet pulp and wheat bran, having different ratios of carbon-nitrogen and moisture levels was used. Further the effect of the amount of inoculum was investigated. Physical parameters for the highest polygalacturonase and polymethylgalacturonase production under solid state conditions were determined on wheat bran: the sugar beet pulp (1:2) mixture substrate composition having a 31:1 carbon-nitrogen ratio with 8 × 10⁶ spores/gram of dry substrate as the inoculum amount. Adequate moisture levels were 75% and 70% for polygalacturonase and polymethylgalacturonase, respectively. Under these conditions, the highest activities obtained were 385 ± 12.3 Ug^?1 on the third day for polygalacturonase and 18.3 ± 3.2 Ug^?1 on the second day for polymethylgalacturonase.     

产纤溶酶菌株根霉12~#的诱变育种及固态发酵培养基的优化

以产纤溶酶的菌株根霉 12 # 为出发菌株 ,对其进行紫外线 氯化锂复合诱变 ,筛选到74株制霉素抗性突变株。所有抗性突变株经进一步固态发酵筛选 ,获得了 4株稳定高产纤溶酶的正突变株 ,其纤溶酶产量分别比出发菌株提高 3 2 9%、2 1 5 %、2 2 3 %和 18 0 %。以其中的 1株为菌种 ,研究了固态发酵产生纤溶酶的培养基组成。采用单因素试验、均匀设计方法对固态发酵培养基的碳源、氮源、碳氮比、初始pH、加水量、无机盐加量进行了优化。结果表明 ,实验范围内根霉 12 # 固态发酵产生纤溶酶的适宜培养基组成为 :m (麸皮 )∶m (豆粕 )=1∶2 ,初始 pH5 0 ,加水量 0 75mL/g物料 ,MnSO4·H2 O和 (NH4) 2 SO4加量分别为 0 2 5 %和1 42 % (对物料 )。优化条件下的固态发酵纤溶酶产量平均达 744 5 7U/g物料。     

Amylase production in solid state fermentation by the thermophilic fungus Thermomyces lanuginosus

The production of extracellular amylase by the thermophilic fungus Thermomyces lanuginosus was studied in solid state fermentation (SSF). Solid substrates such as wheat bran, molasses bran, rice bran, maize meal, millet cereal, wheat flakes, barley bran, crushed maize, corncobs and crushed wheat were studied for enzyme production. Growth on wheat bran gave the highest amylase activity. The maximum enzyme activity obtained was 534 U/g of wheat bran under optimum conditions of an incubation period of 120 h, an incubation temperature of 50 degrees C, an initial moisture content of 90%, a pH of 6.0, an inoculum level of 10% (v/w), a salt solution concentration of 1.5:10 (v/w) and a ratio of substrate weight to flask volume of 1:100 with soluble starch (1% w/w) and peptone (1% w/w) as supplements.     

黑曲霉固态发酵淀粉渣生产木聚糖酶

筛选到一株能在淀粉渣上很好生长,具有较高木聚糖酶活性的黑曲霉(Aspergillus niger)SA_7。在以淀粉渣为原料,初始含水量为65～70％的固体培养基上,28℃培养3天,其木聚糖酶活达2400U/g,且酶系组成齐全。少量的麸皮能提高木聚糖酶的活力。其粗酶液在45℃水解淀粉渣24小时,可得21.6％的还原糖。     

Effects of enzymes in fibre-enriched baking

The aim of the present study was to improve the quality of fibre-enriched wheat breads by enzymic treatment of the fibre fraction. The suitability of different enzymes in fibre-enriched baking and their effects on the dietary fibre content and the ratio of insoluble: soluble fibre content of the breads were studied. The enzyme preparations used were a hemicellulolytic culture filtrate of Trichoderma reesei, a specific (pI 9) xylanase of T reesei and Fermizyme, an α-amylase preparation containing a standardised level of hemicellulase activity. Rye bran was extracted in water (10% (w/w) suspension) to determine the solubilities of the β-glucans and pentosans. Addition of T reesei culture filtrate significantly increased the amount of extractable pentosan obtained from nonautoclaved rye bran. Rye bran supplementation (5%) of wheat flour increased the farinograph absorption and dough development time, but had little or no effect on stability and softening of the dough. The added enzymes decreased dough stability and increased softening. Addition of enzymes caused significant differences in the stickiness of the wheat doughs both with (P<0·003) and without (P<0·001) rye bran. Fermizyme significantly increased the stickiness of wheat doughs both with and without rye bran. The baking results of the fibre-enriched breads were improved by the added enzymes. Addition of T reesei culture filtrate increased the specific volume of the wheat breads both with and without rye bran by almost 20%. Enzyme mixtures were more efficient than individual xylanase in softening the bread crumb and reducing the staling rate of wheat breads both with and without rye bran. Incorporation of enzymes reduced the total dietary fibre content of the breads, but at least doubled the amount of soluble pentosan. The proportions of fluorescent cell walls in the breads were detected by microscopical image analysis. Enzyme addition caused the surface area of insoluble cell walls originating from wheat flours to decrease, suggesting that the enzymes exert more effects on wheat endorsperm cell walls than on bran particles. © 1998 SCI.     

Fat,wheat bran and salt effects on cooking properties of meat patties studied by response surface methodology

Response surface methodology was used to investigate the main effects and interactions of composition (processing) variables such as fat (10–30%), wheat bran (5–15%) and NaCl (0–2%) on cooking properties of beef patties. In addition, the ridge analysis was conducted to find the values of processing variables that maximise and minimise the cooking parameters (moisture retention, fat retention, reduction in thickness, reduction in diameter, cooking yield, shrinkage and water‐holding capacity). It was found that the moisture and fat retention, reduction in thickness and cooking yield values decreased; however, reduction in diameter and shrinkage values increased, respectively, as the amount of fat increased. However, wheat bran addition increased fat retention, moisture retention, cooking yield and water‐holding capacity values of the patties. Increasing NaCl levels decreased water‐holding capacity value by its quadratic effect and moisture and fat retention value by its interaction effect with wheat bran.     

Production of Starch Saccharifying Enzyme (Glucoamylase) in Solid Cultures

A laboratory process was established for the production of glucoamylase (amyloglucosidase) enzyme by Aspergillus niger (RRL isolate), using wheat bran of mixed particle size as main carbon source in solid cultures. The experimental studies were carried out in 500 ml conical flasks and subsequently in tray fermenters in static conditions. Experiments were conducted to monitor the impact of initial moisture content of the substrate as well as the steam cooking of the substrate on different atmospheric pressure on the productivity of the enzyme. An initial moisture level of 50–55% was found optimum for glucoamylase production when fermentation was carried out for 96h. Cooking of substrate at 1056 kg/cm² under steam for 30 min gave most desirable qualities in substrate.     

Effect of Degree of Polishing on Milling Characteristics and Proximate Compositions of Barnyard Millet (Echinochloa frumentacea)

Polishing of barnyard millet was done in rice polisher. Degree of polishing was obtained from 3 to 6 min time of milling at an increment of 1 min at 8%, 10%, 12% and 14% of moisture levels. At each moisture level and degree of polishing, proximate compositions (protein, fat, fibre, ash and carbohydrates) were analysed. At 8% moisture, barnyard millet was more resistant to polishing and yielded 18.86% of bran after 6 min of milling, while at 14% moisture it was 19.21%. The amount of bran removed increased significantly with time of milling and was best described by power model when regression analysis was carried out. The milling and head yield decreased linearly with the degree of polishing. For the entire range of milling time, at 10% moisture content, there was highest head yield (52.97%). The broken millet recovery increased in proportion to the degree of polishing. Regression analysis showed that the power model was the best fit. The milling time caused a reduction in the proximate compositions. The maximum loss in protein, fat, ash and fibre took place at 14% moisture content followed by 12%, 10% and 8% moisture levels. Protein, fat, ash and fibre were negatively and linearly correlated with degree of polishing.     

干酪乳杆菌(HN-2)固态发酵培养基的优化

该研究选择一株具有水质净化能力的干酪乳杆菌(Lactobacillus casei HN-2),以麸皮及米糠为主要基质对其开展了固态发酵研究。通过部分因子析因试验设计及响应面分析,获得了最佳的固体培养基组合,包括:麸皮6.87g、米糠9.84g、葡萄糖0.26g、大豆蛋白胨0.10g、MgSO4.7H2O 0.05g、CaCO30.25g、K2HPO4.3H2O 0.10g。当初始湿度为65%、初始pH值为6.0时,在37℃经过48h的固态发酵,干酪乳杆菌HN-2的菌体密度最大可达2.47×1010cfu/g。     

Short communication: Effect of increasing levels of corn bran on milk yield and composition

Thirty-nine lactating Holstein cows (23 multiparous and 16 primiparous) were randomly assigned to 1 of 3 dietary treatments in a crossover design. Dietary treatments differed by the proportion of corn bran [10, 17.5, and 25% dry matter (DM); designated as low, medium, and high] replacing corn silage and alfalfa. The corn bran coproduct contained 8.2% moisture and 12.9% crude protein, 30.4% neutral detergent fiber (NDF), and 45.0% nonfiber carbohydrate, 9.9% ether extract, and 0.70% P (DM basis). The low treatment consisted of 15.8% NDF from forage (fNDF) and 33.1% total NDF; the medium treatment consisted of 12.9% fNDF and 32.5% total NDF; and the high diet contained 9.9% fNDF and 31.8% total NDF. Dry matter intake was not affected by treatment. The percent milk fat decreased by 0.26% with the inclusion of corn bran from 10 to 25% of the diet DM, but total milk fat yield was not affected. In comparison, corn bran increased yield of milk protein 0.12 kg/d when bran increased from 10 to 25% of the diet DM. Total milk yield tended to increase when bran increased from 10 to 25% of the diet DM, but no differences were observed on 3.5% fat-corrected milk. Lastly, feed conversion significantly improved with increasing inclusion: 1.39, 1.39, and 1.55 ± 0.05 kg of milk/kg of DMI for low, medium, and high, respectively. Observed effects were likely due to the increase in energy intake associated with increasing levels of corn bran.     

全脂米糠膳食纤维化挤压及可溶性工艺技术研究

为了探索全脂米糠粉挤压规律,以纤维素酶为催化剂,利用双螺杆挤压机做生化反应器对全脂米糠粉进行了挤压试验研究,获得了具有不同膳食纤维含量的挤出物。在单因素研究的基础上,采用了五元二次正交旋转组合设计(1/2)实施研究了机筒温度、螺杆转速、物料水分、加酶量和模孔直径对挤出物膳食纤维含量的影响规律。结果表明:5个因素对膳食纤维得率的影响大小依次为水分(X2)机筒温度(X4)pH值(X1)酶添加量(X3)螺杆转速(X5)。在pH值6.5、水分39%、加酶量3.5%、转速110r/min和机筒温度125℃条件下,所得全脂米糠粉中膳食纤维产率为33.51%。可溶性膳食纤维含量为9.9%。     

Use of Hydration, Germination, and α-Galactosidase Treatments to Reduce Oligosaccharides in Dry Beans

ABSTRACT: This investigation was done to determine an energetically feasible method to reduce bean oligosaccharides (stachyose and raffinose) for large-scale bean flour production. Michigan black, red, and navy beans (all Phaseolus vulgaris ) were treated by α-galactosidase, germination, or hydration to determine treatment effects on stachyose and raffinose levels. Oligosaccharides were extracted with 70% (w/w) ethanol, and α-galactosidase was added to catalyze hydrolysis of the oligosaccharides. Enzyme treatment was for 1 h at ambient temperature (23°C). For germination, whole beans were incubated in a germinating chamber (100% humidity, 26.7°C) for 48 h. In hydration, whole beans were soaked in excess water at ambient temperature (23°C) for 5 h. Enzyme treatment resulted in 51%± 3.0%, 30%± 1.9%, and 46%± 1.9% reduction in total raffinose and stachyose for black beans, red beans, and navy beans, respectively. Germination treatment resulted in 61%± 12%, 61%± 1.9%, and 70%± 2.8% reduction in total raffinose and stachyose for black beans, red beans, and navy beans, respectively. Hydrated black beans showed a loss of 33%± 9.6%, whereas hydrated red and navy beans showed no reduction of oligosaccharides. Although germination showed the greatest reduction in bean oligosaccharides, this method may not be as cost-effective commercially as the enzyme treatment because of the time required for germination.     

黑曲霉固态发酵产羧肽酶条件优化及在酱油酿造中的应用

该研究以羧肽酶活力为考察指标,采用响应面法对1株高产羧肽酶的黑曲霉（Aspergillus niger）H1-6固态发酵产酶条件进行优化。首先采用单因素试验结合Plackett-Burman（PB）试验筛选出重要影响因子：麸皮添加量、水分含量和接种量,通过最陡爬坡试验获得重要影响因子的峰值范围,最后采用Box-Behnken试验、响应面分析对重要影响因子进行优化。结果表明,黑曲霉H1-6的最优产酶培养条件为：麸皮添加量36%、豆粕添加量50%、NaCl添加量10%、pH值为6.0、含水量56.6%,接种量1.3%。在此优化条件下,固态发酵羧肽酶的酶活力达到938.33 mU/g。将该羧肽酶粗酶液添加到酱油酿造中,能有效提高酱油中氨基态氮的含量（达到1.38 g/100 mL）,进而提高其鲜味。     

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.     

EFFECT OF PARTICLE SIZE ON THE WATER SORPTION PROPERTIES OF CEREAL FIBERS1

Six particle size fractions were prepared by grinding and sieving stabilized hard red wheat bran, oat fiber, and corn bran. Water adsorption indices (WAI's) and effective diffusion coefficients (D_eff) were measured for all size fractions. WAI's of wheat bran decreased with particle size. WAI's of oat bran increased as particle size decreased and the WAI's of corn bran fractions did not vary as much as the other fibers. The D_eff's of wheat increased, of oat decreased, and of corn were about the same as the particle size decreased. The wheat D_eff was less than that of corn which was less than that of oats. Monolayer moisture content and bulk moisture content at high A_w were determined from moisture sorption isotherms measured on the smallest particles. There was no difference in the monolayer moistures but both corn and wheat brans adsorbed much more water at high A_w than did the oat bran. Effect of particle size on water sorption and, by inference, some types of functionality cannot be generalized and must be determined for each type of fiber.     

Optimizing Quality of Frankfurters Containing Oat Bran and Added Water

Chicken frankfurters fat content was decreased by using various levels of oat bran and added water and evaluated for quality. Frankfurters with higher levels of oat bran had less expressible moisture and required higher shear stress to break. There were no difference in springiness among frankfurters made with different levels of oat bran; however, those with higher oat bran were rated less juicy and more grainy by taste panelists. The addition of water increased intensities of strain, springiness and juiciness, but decreased shear stress and hardness values. Contour plots showed optimum formulation at <2% oat bran 20% of added water.     

Water sorption and cooking time of red kidney beans (Phaseolus vulgaris L.): part I – Effect of freezing and drying conditions on water sorption and cooking time

Water sorption and cooking time of kidney beans were determined. The beans were manually harvested at 19.2 ± 0.1% moisture content and stored at ?20 and ?10 °C for about half a year. The beans were further dried at 30, 40 and 50 °C inside a thin‐layer drier for 7.5 h or under room conditions for 4 week. The freezing storage temperature before the beans were dried did not influence their cooking time and water sorption. The saturated kernel volumes decreased approximately 7% after drying. The beans decreased their sphericity during water sorption and had a larger swelling ratio in the thickness direction than in other directions. Lower initial moisture content, especially with a higher drying temperature, decreased water sorptivity and resulted in higher percentage of uncooked kernels if the beans were not soaked before cooking. However, there was no relationship between initial moisture content and uncooked percentage if the beans were soaked before cooking. High drying temperature resulted in hard‐to‐cook (HTC) phenomenon.     

多菌种复合制曲技术研究

从山西老陈醋大曲和镇江香醋小曲以及酱油曲中分离纯化特定菌种,并经过诱变获得高产菌株,将其接种于由大麦、豌豆、麸皮、荞麦和绿豆5种原料制备的复合曲中,所制备的多菌种复合曲酶活较高,酯化力提高23.91%,蛋白酶活提高17.50%,为开发高品质多香型食醋奠定了基础。     

Yield and Quality of Tofu as Affected by Soybean and Soymilk Characteristics: Glucono-delta-lactone Coagulant

Nine light hilum soybean [Glycine max (L.) Merr] cultivars were used to study characteristics that affect yield and quality of tofu (soybean curd) coagulated with glucono-delta-lactone (GDL). Pressed and packed (nonpressed) curds were examined. Yield of tofu was not affected by size of beans. Protein and total solids in soymilk increased when protein and moisture increased in soybeans. Yield of pressed GDL tofu increased with protein content of soybeans (or soymilk) plus decreased calcium content. Fracturability of pressed GDL tofu increased with levels of phosphorus. Hardness of packed tofu increased with protein content in soymilk. Yield of pressed GDL tofu was 20% higher than CaSO₄ tofu.