Antinutritional and/or toxic factors in soybean (Glycine max (L) Merril) seeds: comparison of different cultivars adapted to the southern region of Brazil

Soybean (Glycine max (L) Merril) seeds are known to contain different proteins displaying antinutritional and/or toxic effects, such as soybean agglutinin (an N‐acetylgalactosamine‐specific lectin), proteinase inhibitors (Kunitz‐ and Bowman–Birk‐type trypsin and chymotrypsin inhibitors) and urease (seed and tissue isoforms). Two other toxic proteins were previously isolated from soybeans, soyatoxin (21 kDa) and soybean toxin (18.4 kDa), which are immunologically related to canatoxin, a toxic protein from Canavalia ensiformis (jackbean) seeds. In this work we have screened crude extracts from seeds of six different soybean cultivars, which together represent most of the crop harvested in the southern region of Brazil, for the presence of urease, trypsin inhibitory and haemagglutination activities, intraperitoneal toxicity in mice and immunoreactivity against anti‐canatoxin antibodies. Significant differences were found in the contents of proteinase inhibitors, lectin, urease activity and lethality in mice. The relevance of these findings to the agronomic qualities and to the choice of soybean cultivars to be used as food or feed is discussed. Copyright © 2004 Society of Chemical Industry     

Highly effective inactivation of anti-nutritional factors (lipoxygenase,urease and trypsin inhibitor) in soybean by radio frequency treatment

Radio frequency (RF) treatment at 27.12 MHz was employed to inactivate the anti-nutritional factors (ANFs), including lipoxygenase (LOX), urease and trypsin inhibitor to minimise deleterious effects caused by conventional hot-air heating. The effects of RF heating on the ANF activities, physicochemical properties and processing quality of intact soybean were investigated. The results revealed that ANF activities were effectively inactivated within 300 s by RF heating and inactivation rates of LOX, urease and trypsin inhibitor were 95.2% (270 s), 93.4% (285 s) and 89.4% (300 s), respectively. In addition, RF heating improved physicochemical properties and processing quality of soybean products when the trypsin inhibitor was inactivated. On the contrast, conventional thermal treatment significantly decreased functional properties and led to the formation of greater aggregates. Our results may provide a novel method to inactivate endogenous enzyme in crops without negative impact on processing quality.     

Effect of Cooking on Firmness, Trypsin Inhibitors, Lectins and Cystine/Cysteine content of Navy and Red Kidney Beans (Phaseolus vulgaris)

The effect of cooking on firmness, trypsin inhibitor (TI) and lectin activities, and cystine/cysteine (Cys) of navy and red kidney beans was investigated. Beans were soaked and cooked in an open-kettle at various temperatures and periods. Navy beans canned by two methods were used for comparisons with the open-kettle cooked beans. The TI activity, lectin activity and Cys content decreased with increasing temperature and/or period. Under some of the cooking conditions, less than 5.5% and 0.1% of TI and lectin activities, respectively, were retained, though the firmness of beans was palatable. Canned navy beans did not have lectin activity but had less than 5% residual TI activity.     

Nutritional and antinutritional composition,in vitro amino acid availability,starch digestibility and predicted glycemic index of differentially processed mucuna beans (Mucuna pruriens var. utilis): an under-utilised legume

The effects of different solutions, water, 0.07% sodium bicarbonate, 0.1% ascorbic acid and 3% moringa leaf powder in water, and soaking, followed by autoclaving, on the proximate composition and antinutrients, in vitro amino acid digestibility, starch hydrolysis index (HI) and glycemic index (GI) of Mucuna pruriens var. utilis seeds were evaluated. Even though none of the processing techniques affected the proximate composition on gross energy value, they significantly (P<0.05) reduced the levels of various antinutrients, such as total phenolics, tannins, phytates, saponins, l-dopa, trypsin inhibitor (TI), chymotrypsin inhibitor (CI) and lectin activities of the respective samples. Nonetheless, all the processing methods improved the total protein digestibility and individual amino acid availabilities, particularly those of methionine, tyrosine, lysine and arginine, without affecting the protein quality. When compared to the raw seed sample, all the hydrothermal processing increased the total (TS) and digestible (DS) starch content (351–361 and 303–315 g kg⁻¹, respectively) and decreased the resistant starch (RS) content (46.1–48.1 g kg⁻¹) significantly (P<0.05). The in vitro starch digestion rate was also measured in the freshly processed seed samples, and the values of HI and GI were comparable to that of similarly processed legumes such as moth bean and black gram.     

Composition,toxic and antinutritional factors of newly developed cultivars of Brazilian soybean (Glycine max)

Five different recently released Brazilian soybean cultivars (Bays, BR-10, Rio Balsas, Serido and Tropical) were compared for their proximate analyses and presence of antinutritional or toxic factors. As expected, the seeds are rich in proteins, varying from 360·7 to 485·4 g kg⁻¹ flour, and they also have a high amount of fat (from 183·0 to 215·3 g kg⁻¹ flour). Crude extracts from seeds of Bays, BR-10, Serido and Tropical were highly toxic to mice within 1–12 h, depending on the administration route (intraperitoneal, intramuscular or subcutaneous) and dose used while Rio Balsas was not. These acute effects were very similar to those produced by the soytoxin, a neurotoxin that has been recently purified from the commercial soybean sold in Brazil. The amount of trypsin inhibited in the presence of crude extracts ranged from 28·5 to 62·5 g kg⁻¹ flour. Urease was also present and the seed lectin agglutinated preferentially rabbit erythrocytes. A heat treatment at 92°C for 1 min destroyed completely the toxic activity while the haemagglutinating and trypsin inhibitor activities were abolished within 5 min. At these conditions urease was still active. Due to its high protein content, lack of soytoxin, and low levels of trypsin inhibitor, lectin, and urease it is suggested that Rio Balsas could be an alternative for breeding programmes aimed to improve the nutritional quality of soybeans. ©1997 SCI     

Effects of heating on protein quality of soybean flour devoid of Kunitz inhibitor and lectin

The effects of autoclaving on protein quality of soybean flours prepared from a conventional soybean (CSB) and an isoline lacking Kunitz inhibitor and lectin (KFLF) were studied. The heating was efficient in the urease, trypsin inhibitors and lectin inactivation, being 15 min sufficient to reduce more than 90% of these compounds and provide protein solubility over 80%. The results of PER, NPR and weight gain showed that heating equally improved the nutritional quality of both soybean flours, although higher autoclaving time was required for KFLF. No significant improvement was observed on NPU and in vivo digestibility of the diets containing KFLF at any heating time. As these later results were similar to those obtained with diets containing CSB, they show the importance of the heating to improve the nutritional value and show that other components rather than trypsin inhibitors and lectins impair the nutritive value of raw soybean.     

Effect of soaking,dehulling, and cooking methods on certain antinutrients and in vitro protein digestibility of bitter and sweet lupin seeds

Effect of several physical treatments (soaking, dehulling, ordinary cooking, microwave cooking, and autoclaving) on the level of antinutrients and in vitro protein digestibility of bitter and sweet lupin seeds were investigated. The raw bitter and sweet lupin seeds were found to contain phytic acid, tannins, trypsin inhibitor activity, and lectin activity, but α-amylase inhibitor was absent. Dehulling significantly increased the levels of phytic acid (PA), trypsin inhibitor activity (TIA), and tannins, but lectin activity was not changed. Also soaking in bitter (for 96 hr) and sweet (for 24 hr) seeds caused a significant increase in these factors except lectin activity. Cooking methods differently affected the levels of the antinutrients. Thus, PA increased but tannins were not changed, on the other hand TI and lectin activities were inactivated; ordinary cooking and autoclaving were the most effective in both seeds. For combination effect, soaking following cooking treatments significantly decreased PA, tannins, and lectin activity, but increased TIA in both seeds. Moreover, dehulling following soaking and cooking methods resulted in a significant increase of PA, TIA, and tannins. In vitro protein digestibility (IVPD) of raw bitter and sweet lupin seeds were 78.55 and 79.46%, respectively and it was improved by all processing methods; soakingdehulling after autoclaving was the most effective in both seeds. Although some treatments increased the level of antinutrients, they improved IVPD. Therefore, the studied antinutrients are not the only responsible factor for lowering IVPD.     

A survey of the use of soy in processed Turkish meat products and detection of genetic modification

To screen for possible illegal use of soybeans in meat products, the performance characteristics of a commercial polymer chain reaction (PCR) kit for detection of soybean DNA in raw and cooked meat products were established. Minced chicken and beef products containing soybean at levels from 0.1% to 10.0% were analysed by real-time PCR to amplify the soybean lectin gene. The PCR method could reliably detect the addition of soybean at a level of 0.1%. A survey of 38 Turkish processed meat products found only six samples to be negative for the presence of soybean. In 32 (84%) positive samples, 13 (34%) contained levels of soy above 0.1%. Of soybean positive samples, further DNA analysis was conducted by real-time PCR to detect whether genetically modified (GM) soybean had been used. Of 32 meat samples containing soybean, two samples were positive for GM modification.     

大豆萌发期脂肪氧化酶与脲酶活性变化及钝化方法效果评价

为探究大豆萌发期抗营养因子含量变化规律及钝化方式,以黑龙江地区的黑科56、黑农71为原料,测定此两种萌发大豆在不同萌发时间阶段中脂肪氧化酶和脲酶两种抗营养因子的活性变化,并在萌发20 h酶活性至最低时,分别以烘烤、微波、沸水漂烫3种方法处理萌发豆,比较对脂肪氧化酶与脲酶的钝化效果,筛选出适宜的钝化方式并确定其工艺参数。结果表明,萌发20 h黑科56与黑农71脂肪氧化酶活性分别为100.8 U和99 U,脲酶活性分别为4.73 U/g和4.82 U/g;钝化方式效果最佳为沸水漂烫,其工艺参数为:沸水漂烫40 s,两个品种与未漂烫的大豆相比,脂肪氧化酶活性均降低至10.9 U;脲酶活性分别降低至0.18 U/g(黑科56)和0.13 U/g(黑农71)。通过顶空固相微萃取-气相色谱-质谱联用法对钝化后的两种萌发大豆主要豆腥味物质进行了定性、定量分析,且得出脂肪氧化酶活性与豆腥味物质含量呈极显著正相关。     

Optimization of acid hydrolysis conditions for total isoflavones analysis in soybean hypocotyls by using RSM

The optimum hydrolysis conditions of soybean hypocotyls with HCl for a quantitative HPLC determination of total isoflavones (TI) were studied by using response surface methodology (RSM). HCl concentration (HC), hydrolysis time (HT) and reaction temperature (RT) were assumed to be the most important factors affecting hydrolysis for the determination of TI. Optimum hydrolysis conditions for maximizing the determination of TI were: HC=3.42N, HT=205.5 min and RT=44.6°C. The model had a satisfactory coefficient of R² (=0.967) and was verified experimentally. Furthermore, the recovery of individual isoflavones was 97–100% under the optimum hydrolysis conditions. The results suggested that the conditions were mild and useful for maximizing a quantitative HPLC determination of TI in soybean hypocotyls.     

挤压膨化对大豆粕营养品质影响研究

以脱脂大豆粕为原料,采用双螺杆挤压技术,研究有效赖氨酸含量随挤压膨化参数变化规律,同时研究大豆粕体外消化率,大豆异黄酮,大豆皂甙,脲酶活性在挤压膨化前后变化。结果表明:有效赖氨酸含量随喂料速度,螺杆转速和水分含量增加而增大,并随挤压温度升高而减小,经挤压膨化,大豆粕体外消化率明显提高,大豆异黄酮含量下降,大豆皂甙含量变化不大,脲酶活性显著降低。     

微波去除大豆抗营养因子的研究

为探讨微波技术在大豆干法加工中应用的可行性,考察微波功率、处理时间对大豆中的抗营养因子胰蛋白酶抑制剂、脲酶及蛋白质溶解性的影响。结果表明：在微波功率3400W处理120s的条件下,胰蛋白酶抑制剂及脲酶钝化率达到80%以上,可有效去除大豆抗营养因子;同时测得蛋白质溶解度约为40%,该处理条件下的豆粉可以作为大豆即时冲调饮品专用原料加以利用。     

大豆凝集素的超声波辅助提取工艺优化及其性质

采用响应面法优化超声波辅助提取大豆凝集素的最佳工艺参数。在单因素试验的基础上,以超声时间、提取温度、提取时间、液料比为自变量,以凝集素提取得率为响应值,优化得到大豆凝集素的最佳提取工艺为：超声时间38 min、提取温度32 ℃、提取时间5.6 h、液料比10∶1（mL/g）。在此条件下得到的凝集素提取得率为9.82%。稳定性测定结果表明：大豆凝集素的最适pH值为7～8,在Ca2＋溶液中较稳定。D-乙酰葡萄糖胺和D-乙酰乳糖胺对大豆凝集素的凝集活力影响大,是大豆凝集素的专一性抑制糖。     

Factors Affecting the Stability of Chlortetracycline, Tylosin and Furylfuramide Against Low Level of Ionizing Radiation

SUMMARY— Effect of low levels of ionizing radiation (0.01–0.2 Mrad) on the stability of chlortetracycline (CTC) , furylfuramide (FF) and tylosin (Tl) were investigated. Tl in the phosphate buffer of pH 6–8 was very sensitive to low-level radiation, while either FF or CTC exhibited fairly high resistance at the same dose levels. Removal of dissolved oxygen in the test solution by aerating with nitrogen gas enhanced the inactivation of TI and FF at 0.05–0.1 Mrad of radiation, but it had an opposite effect on the inactivation of CTC. Much higher TI and CTC activities were retained after irradiation at 0.1 or 0.2 Mrad when the drugs were added to albumin, gelatin, broth or minced meats of five species of fish; the retention of FF did not change.
The remaining activity of Tl at 0.1 or 0.2 Mrad of radiation was more or less influenced by adding various sugars and amino acids. The presence of sugars (mono- or disaccharides) did not change retention of TI markedly, but gave a weak protective effect. Tryptophane, histidine, phenylalanine, methionine and tyrosine exhibited a fairly high protective action on the inactivation of TI after irradiation.     

转基因大豆种植对根际土壤酶活性和养分的影响

采用盆栽试验,以耐草甘膦大豆M88、抗虫耐草甘膦大豆ZB及常规大豆中黄13为研究对象,比较分析转基因大豆对根际土壤酶活性和养分含量的影响。结果表明,在大豆成熟期时,与常规大豆中黄13相比,M88、ZB根际土壤碱性磷酸酶活性、过氧化氢酶活性、速效磷含量无显著差异,硝态氮含量显著下降。根际土壤脲酶活性、铵态氮含量则表现不同,其变化随大豆品种的不同而不同。相较于常规大豆中黄13,M88根际土壤脲酶活性和铵态氮含量无显著差异;ZB根际土壤脲酶活性显著下降,而铵态氮含量则显著上升。     

Functional attributes of soybean seeds and products,with reference to isoflavone content and antioxidant activity

The concentrations of isoflavones, especially daidzein and genistein, were determined by high performance liquid chromatography in 4 soybean cultivars and 26 soybean products. The total isoflavone content of the soybean cultivars was in the range of 525–986 mg per kg, and for soy products it was 32.9–795 mg per kg. Amongst the soybean products, the isoflavone content decreased in the order: soy sprouts, soy seeds, soy flour, soy milk, soy meals and soy sauce. Significant differences in the concentration of genistein and daidzein were observed between the commercial soy products and also within the soybean cultivars. The antioxidant activity of soybean and soy products correlated well with total phenolic content (TPC) and total isoflavones (TI), whereas TPC showed higher correlation with TI.     

Detection of DNA in soybean oil

 The presence of DNA in foodstuffs which are, or contain, genetically modified organisms (GMO) is the basic requirement for labelling of GMO food in Switzerland and is also being discussed as a requirement for labelling in the European Union. The present work presents data indicating that no genetic material can be recovered after the first processing steps of soybean oil, i.e. when crude soybean oil is simply centrifuged. This fact is of some relevance because centrifugation is one of the first steps in industrial oil processing. A nested PCR system utilising a single copy gene (lectin 1) showed that centrifugation purified the oil from the genetic material by at least a factor of 10 000. The same results were observed when industrially processed oil fractions were analysed. Thus, with respect to the presence of DNA, soybean oil from GMO soybeans is identical to traditional oil and does not need to be labelled as a GMO product in Switzerland. Received: 21 January 1998 / Revised version: 30 March 1998     

Detection of DNA in soybean oil

 The presence of DNA in foodstuffs which are, or contain, genetically modified organisms (GMO) is the basic requirement for labelling of GMO food in Switzerland and is also being discussed as a requirement for labelling in the European Union. The present work presents data indicating that no genetic material can be recovered after the first processing steps of soybean oil, i.e. when crude soybean oil is simply centrifuged. This fact is of some relevance because centrifugation is one of the first steps in industrial oil processing. A nested PCR system utilising a single copy gene (lectin 1) showed that centrifugation purified the oil from the genetic material by at least a factor of 10 000. The same results were observed when industrially processed oil fractions were analysed. Thus, with respect to the presence of DNA, soybean oil from GMO soybeans is identical to traditional oil and does not need to be labelled as a GMO product in Switzerland. Received: 21 January 1998 / Revised version: 30 March 1998     

Protease inhibitors and lectins in soya beans and effects of aqueous heat-treatment

Protease inhibitor and lectin concentrations and N and lipid levels were evaluated in 27 soya bean samples. All contained trypsin and chymotrypsin inhibiting activity and lectin. Shinano midori, Shinano wasediro, Shinano-oomame and Tsuronoku had high protein contents and average lipid levels, and their lectin and trypsin and chymotrypsin inhibitory activities were not unduly high. These lines, in particular, merit further nutritional evaluation. Food intake, feed conversion efficiency and growth by rats was reduced when soya bean was included in their diet, but the extent to which these parameters were affected did not appear to depend only on the protease inhibitor or lectin content. In contrast, pancreatic and small intestinal growth did seem to reflect the levels of these factors in the diet. Chymotrypsin inhibitor activity in soya bean was more readily abolished by heat-treatment than was trypsin inhibitory activity. Lectin activity was also relatively heat-resistant. However, all of these activities could be abolished by aqueous heat-treatment of fully imbibed seeds at 100°C for 10 min. The effects of a soya diet on pancreas and small intestine weights were also abolished by this pre-treatment, and food intake and nutrient utilisation by rats was greatly improved. © 1998 Society of Chemical Industry     

Heating process of soybean using hot-air and superheated-steam fluidized-bed dryers

The present work investigated drying characteristics and inactivation of urease in soybean dried by superheated-steam and hot-air fluidized beds. The value of effective diffusion coefficient, which was determined by a method of slopes, was increased with increased drying temperature and increased moisture content. Furthermore, it depended on the type of heating medium, with higher moisture diffusion for soybean dried by hot air. Inactivation of the urease enzyme in both media showed difference in rate, in which the enzymatic inactivation was faster for soybean dried in superheated steam than in hot air. For the individual heating medium, the modified first-order reaction was adequately fitted to experimental data. The rate of inactivation was found to increase as the temperature and moisture content were increased. The urease enzyme was inactivated, along with maintaining protein solubility and lysine content being in standard range, as soybean was treated at a temperature between 135 and 150 °C for the hot air and the treatment temperature could be reduced to be lower than 135 °C by using superheated steam.