Volatile compounds in Bacillus‐fermented soybeans

Thua nao, a traditional, proteolytic, fermented soybean condiment of northern Thailand, was prepared from cooked whole soybeans by natural flora fermentation. The microbial flora during the fermentation was dominated by Bacillus species. The formation of volatile compounds during the fermentation was studied. In addition, the volatile compounds of two samples of commercial dried thua nao and two samples of commercial Japanese natto were analysed. Fermentation led to a large increase in the concentration of total volatile compounds, from 35 µg kg^?1 wet weight in cooked soybeans to 3500 µg kg^?1 wet weight in 72 h fermented material. The major volatile compounds in fermented beans were 3‐hydroxybutanone (acetoin), 2‐methlybutanoic acid, pyrazines, dimethyl disulphide and 2‐pentylfuran. Sun drying of 72 h fermented material resulted in the loss of 65% of total volatiles, including important aroma compounds. The commercial dried thua nao samples had low concentrations of total volatile compounds (380 µg kg^?1 wet weight). It is suggested that improved drying/preservation methods are needed to retain aroma compounds in the traditional products. The natto samples were devoid of aldehydes, aliphatic acids and esters, and sulphur compounds, whereas the thua nao samples contained a diversity of these compounds. Previous investigators have reported these compounds in natto and it is not possible to suggest the existence of systematic differences between the volatile compounds in traditional thua nao prepared with an undefined, mixed microbial flora and those in natto fermented with Bacillus subtilis. © 2001 Society of Chemical Industry     

Off‐flavour development in soybeans: comparative role of some antioxidants and related enzymes

Off‐flavour development is the major impediment in the effective use of soybeans as food ingredients. In the present study, the levels of vitamin E and vitamin C along with those of antioxidant enzymes, like superoxide dismutase, peroxidase and catalase, were estimated in sixteen soybean varieties to explore their effectiveness against off‐flavour generation. Thiobarbituric acid (TBA) number, an indicator of lipid peroxidation, was used to measure the quality with respect to off‐flavour. Data on activities of various antioxidant enzymes indicated that the off‐flavour is mainly generated enzymatically by the action of lipoxygenase on polyunsaturated fatty acids. Furthermore, varieties PK 416 and JS 7105 had the highest level of vitamin E while their TBA number was the lowest indicating the inverse relationship between the two parameters. It was further observed that the peroxidative effect of higher vitamin C concentrations is controlled by vitamin E. Among the varieties analyzed, PK 416 and JS 7105 appeared to have greater potential as most acceptable food ingredients. Copyright © 2004 Society of Chemical Industry     

米曲霉发酵法制作豆豉新工艺

为解决传统豆豉生产方法中存在的问题,该文介绍了利用米曲霉发酵法生产豆豉,它可突破季节性限制,减轻劳动强度,使生产周期大大缩短。其主要操作要点是：大豆筛选、蒸煮、拌粉、制曲及发酵。同时,介绍了产品标准。成品豆豉颗粒松散,清香鲜美,有较高的实用价值,值得推广应用。     

B-group vitamin and mineral contents of soybeans during kinema production

Concentrations of several B-group vitamins, determined by high-performance liquid chromatography (HPLC), and minerals, determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), in soybeans during different kinema production stages were compared. After soaking soybeans in water, thiamine (B₁) content decreased, whereas riboflavin (B₂) content remained unchanged. Cooking had no influence on the B₁ content, but it enhanced the level of B₂ and niacin (B₃). Incubation of beans at 37°C for 48 h, when mixed with Bacillus subtilis, caused an increase in concentration of both B₁ and B₂. Vitamin B₁ levels decreased when either Enterococcus faecium accompanied B subtilis or the temperature was elevated for 18 h fermentation. Traditionally prepared kinema contained 8 mg B₁, 12 mg B₂, 45 mg B₃, 683 mg Ca, 4 mg Cu, 18 mg Fe, 494 mg Mg, 10 mg Mn, 1257 mg P, 2077 mg K, 13 mg Zn and <0·5 mg of Cd, Cr, Pb, Ni and Na per kg dry matter. While the vitamin B₁ content was significantly (P<0·05) higher, the contents of vitamins B₂ and B₃ were significantly (P<0·05) lower in raw soybeans than those in kinema. Mineral concentrations were 3·1–8·3 times higher in raw soybeans than in kinema. © 1998 Society of Chemical Industry.     

Concentration of phytoestrogens in soybeans and soybean products in Korea

Concentrations of total isoflavones in soybean varieties of different origins and soybean products were determined by high performance liquid chromatography. Wild soybeans showed the trend to have more isoflavone content than cultivars or landraces, showing mean value of 1528, 1265 and 1249 mg kg⁻¹, respectively. There were no meaningful differences in the ratio of genistein and daidzein among the modern variety groups. Korean varieties including South Korea and North Korea seemed to have total isoflavone content more than Chinese varieties, although samples of Chinese varieties were limited. In a dried basis of soyfoods, total isoflavone contents were in order of soybean sprout, chungkukjang, soymilk, soybean curd, denjang, kochujang, respectively. Five soybean foods contributed 96% of total genistein and daidzein intake in Korea: soybean sprout, soybean curd, denjang, chungkukjang and soybean seed itself. According to a Korean National Survey Report and our data, the average Korean daily intake of isoflavone from soybean foods can be estimated as 21 mg day⁻¹. © 2000 Society of Chemical Industry     

Comparisons of flavonoids and anti-oxidative activities in seed coat,embryonic axis and cotyledon of black soybeans

Flavonoids contents, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging activities and the ferric-reducing antioxidant power (FRAP) were compared in three black soybean varieties CRWD, Tainan 3 and Tainan 5. Varietal differences in antioxidant contents existed among the tested varieties. Variety CRWD accumulated more total phenolics (7.49 mg g⁻¹) and isoflavones (1.77 mg g⁻¹) than varieties Tainan 3 (7.05 mg g⁻¹ total phenolics and 1.58 mg g⁻¹ isoflavones) and Tainan 5 (4.38 mg g⁻¹ total phenolics and 0.63 mg g⁻¹ isoflavones). CRWD also accumulated more proanthocyanidins in seed coat than Tainan 3 and Tainan 5. CRWD also demonstrated greater DPPH and FRAP activities than the other two cultivars. Stepwise regressions indicated that both DPPH and FRAP activities were correlated well with the total contents of phenolics and flavonoids, with total phenolics being the most important anti-oxidative factor. The present results indicate that CRWD has greater anti-oxidative responses than Tainan 3 or Tainan 5, and is useful in functional food and other applications.     

超声辅助法提取分离大豆皂苷的实验研究

以大豆废渣为原料,大豆皂苷产率为评价指标,采用索氏提取法、超声波法、超声波与有机溶剂联合提取法进行了提取分离大豆皂苷的实验研究。实验考察了超声功率、时间、温度、料液比对大豆皂苷产率的影响,并在单因素考察基础上,通过正交实验设计得出优化工艺条件。结果表明,超声法可提高皂苷的提取率和节省提取时间,具有节能、提取快速、提取率高的特点,对大豆皂苷的抗氧化活性无显著影响。     

大豆储藏真菌危害早期预测的研究

对大豆储藏中水分和温度的变化,与真菌生长关系进行了研究,建立了一种大豆真菌危害早期预测方法。将样品含水量分别调至11.4%、12.1%、13.0%、13.9%、14.3%和14.7%,经低温平衡后,于10、15、20、25、30、35℃温箱中储藏,每隔10 d取样1次,检测样品中真菌生长变化情况,试验周期为180 d。结果表明,11.4%水分大豆在6个试验温度下储藏均是安全的,12.1%水分样品在20℃以上储藏,检出有真菌生长,随着水分增加,真菌生长逐渐加快,大豆储藏水分与真菌生长速度具有良好的相关性。大豆在15℃以下储藏,低温对真菌生长有明显的抑制作用。超过20℃时这种影响会随着温度上升逐步变小。本试验对不同水分大豆储藏温度与真菌生长起始时间进行了幂函数拟合,得到了大豆储藏水分、温度,及真菌起始生长时间预测关系曲线,通过本曲线,可对高水分大豆短期储藏安全性进行早期预测。     

大豆破碎耦合蒸汽灭酶工艺优化

为最大程度减少豆浆制浆过程中产生的豆腥味,通过破碎耦合蒸汽热烫对浸泡大豆的脂肪氧化酶(lox)进行灭活。以单因素试验为基础,研究蒸汽结束时豆浆的温度、豆浆升温速率和大豆浸泡时间对lox活性和豆浆气味感官品质的影响。然后依据Box-Behnken试验设计原理进行了三因素三水平响应面法优化试验,优化后得到的最佳工艺条件为:温度95.34℃、升温速率0.37℃/s、浸泡时间10.53h。该条件下,lox已完全灭活,同时豆浆气味感官评价好。     

不同来源大豆中生育酚含量的HPLC测定与比较

采用HPLC法测定了东北大豆、黄淮大豆及美国转基因大豆中α、β、γ、δ-生育酚的含量。从所得数据的统计结果来看,东北大豆的α、β-生育酚含量显著高于进口的美国转基因大豆和黄淮大豆,而美国转基因大豆在γ-生育酚含量和生育酚总量方面高于东北大豆和黄淮大豆。东北大豆是生产高质量生育酚(维生素E)的优质资源。     

进境船舶大豆水分含量平均值计算方法的研究

水分含量的测定是进口大豆品质检验的重要环节,而在现有国家标准中并没有就船舶装载散货大豆给出比较详尽的水分含量均值计算方法。通过单因素方差分析法,对水分测定的两组结果进行差异分析,从而确定进境船舶大豆水分含量平均值测定的最优方法,以期作为今后实验室的检测提供依据。     

Optimization of yield and properties of silken tofu from soybeans.

The extraction phase of the preparation of silken tofu was investigated and the ratio of beans:water was shown to be very critical in terms of the amount of protein extracted and the properties of the tofu. In the range 9–14:1, 10:1 gave the best result. Extraction at 8:1 and making up to 10:1 gave much poorer results, but maceration at 8:1 followed by a further extraction at 2:1 gave a better quality tofu. The time of maceration was shown to have a pronounced effect on the amount of protein extracted.     

不同国家大豆生长和质量情况分析及对进口大豆质量情况的反思

对巴西、美国、阿根廷、乌拉圭、俄罗斯及我国黑龙江省种植的大豆生长时间进行了总结,并对39份大豆样品进行检测。结果表明:我国黑龙江省大豆品相最好,百粒重最大,破碎粒和总损伤粒均较低;俄罗斯大豆与我国黑龙江省大豆相比除水分和粗脂肪含量外相差不大;巴西、美国、阿根廷、乌拉圭大豆的粗脂肪含量和粗蛋白含量虽然较高,但杂质、破碎粒和总损伤粒也同样较高。     

Milk production and composition from cows fed small amounts of fish oil with extruded soybeans

Eight Holstein (189 ± 57 DIM) and 4 Brown Swiss (126 ± 49 DIM) multiparous cows were used in a replicated 4 × 4 Latin square with 28-d periods to determine the minimal dietary concentration of fish oil necessary to maximize milk conjugated linoleic acid (CLA) and vaccenic acid (VA). Treatments consisted of a control diet with a 50:50 ratio of forage to concentrate (dry matter basis), and 3 diets with 2% added fat consisting of 0.33% fish oil, 0.67% fish oil, and 1% fish oil with extruded soybeans providing the balance of added fat. Dry matter intake (23.1, 22.6, 22.8, and 22.9 kg/d, for control, low, medium, and high fish oil diets, respectively) was similar for all diets. Milk production (21.5, 23.7, 22.7, and 24.2 kg/d) was higher for cows fed the fat-supplemented diets vs. the control. Milk fat (4.42, 3.81, 3.80, and 4.03%) and true protein (3.71, 3.58, 3.54, and 3.55%) concentrations decreased when cows were fed diets containing supplemental fat. Concentration of milk cis-9,trans-11 CLA (0.55, 1.17, 1.03, and 1.19 g/100 g of fatty acids) was increased similarly by all diets containing supplemental fat. Milk VA (1.12, 2.47, 2.13, and 2.63 g/100 g of fatty acids) was increased most in milk from cows fed the low and high fish oil diets. Milk total n-3 fatty acids were increased (0.82, 0.96, 0.92, and 1.01 g/100 g of fatty acids) by all fat-supplemented diets. The low fish oil diet was as effective at increasing VA and CLA in milk as the high fish oil diet, showing that only low concentrations of dietary fish oil are necessary for increasing concentrations of VA and CLA in milk.     

黑龙江省2014年大豆转基因情况普查与分析报告

对黑龙江省大豆主产区绥化、齐齐哈尔、双鸭山和黑河4个地区不同市县田间种植的800个大豆样品和产区4个粮库80个大豆样品进行转基因成分普查和检测。结果表明:黑龙江省田间种植的大豆样品100%为非转基因大豆,因此黑龙江省大豆主产区保持了非转基因原产地种源;而粮库四的大豆样品被检出含有GTS40-3-2转化事件,转基因大豆样品数量占粮库样品总数量的12.5%,说明转基因大豆已经混入粮库,呼吁国家相关部门对此引起高度重视,进一步加强原产地保护。     

Changes in the concentration of carbohydrates during the soaking of soybeans for tempe production

Soybeans were soaked for 24h in tap water at 30°C in preparation for tempe fermentation. Soaking was conducted under conditions that give a microbial fermentation, and in the presence of antibiotics where microbial growth was inhibited. Sucrose, stachyose and raffinose were the main di- and oligosaccharides in the beans, and their concentrations decreased by 84, 65 and 50%, respectively, during soaking. Glucose, fructose and galactose were found in the soak-water along with lesser amounts of sucrose, melibiose, raffinose and stachyose. Glucose was the main substrate for microbial growth in the soak-water. The concentrations of mono-, di-and oligosaccharides in the beans and in the soak-water were determined by the activity of invertases and α-galactosidases endogenous to the beans, diffusion of the sugars into and out of the bean, and the species of micro-organism growing in the soak-water.