The trypsin inhibitor content of 61 wild edible plant foods of Niger

In the western Sahel and many other regions of sub-Saharan Africa,wild edible plants contribute significantly to human diets, notonly during periods when cereal staples are scarce, but also whenthey are readily available. Although there have been publishedreports regarding the nutrient contents of these plant foods,little attention has been devoted to their content of antinutrientssuch as calcium chelators and inhibitors of the pancreas-derivedproteases, trypsin and chymotrypsin, which are required for theefficient digestion and absorption of dietary proteins. In thisstudy, aqueous extracts of 61 different leaves, seeds, fruits andflowers of edible plants gathered in the Republic of Niger wereanalyzed for their content of trypsin inhibitory substances using-N-benzoyl-DL-arginine-p-nitroanilide as the substrate andbovine trypsin as the enzyme source. Twelve of these plant foodscontained more antitrypsin activity than soybeans (1.34–8.18 vs.1.32 g trypsin inhibited/mg dry weight). Boiling for 3 mindid not inactivate the antitrypsin activity in most of the plantextracts. These data confirm that more than half of the wildedible plant foods widely consumed by various populations whoinhabit the western Sahel contain significant quantities of heat-stable trypsin inhibitor that could possibly compromise thebioavailability of proteins present in the diets of these populations.     

Nutritive value and effect of blanching on the trypsin and chymotrypsin inhibitor activities of selected leafy vegetables

Proximate composition, energy, mineral and vitamin contentsand the effect of blanching methods and times on the trypsinand chymotrypsin inhibitor activities were studied usingcabbage, collard, turnip, peanut, and sweet potato leaves.Results of this study indicated that, crude protein, crudefat, carbohydrate and ash contents were in the range of 15.5–25.6%, 1.4–6.5%, 60.4–73.1% and 6.8–7.5%,respectively. Total dietary fiber was lowest in cabbage (28.2 g/100 g) and highest in the collard leaves (43.1%)while energy content per 100 g of vegetables was highestin sweet potato leaves (402 kcal) and lowest in cabbage(379 kcal). The mineral content per 100 g of vegetableswere in the range of 33.4–249.8 mg, 241.2–471.2 mg,12.1–75.1 mg, 14.9–98.9 mg, 0.5–3.5 mg and 0.9–3.1 mgfor Ca, K, Na, Mg, Fe and Zn, respectively. For ascorbicacid, riboflavin, thiamin and total carotenoids, concentrations in 100 g of vegetables were in the range of45.1–112.7 mg, 0.2–0.3 mg, 0.3–0.8 mg and 2.0–7.3 mg,respectively. The trypsin inhibitory activity per gram ofthe vegetables was highest in collard (60.1 TIU/g) andlowest in peanut leaves (41.0 TIU/g). Chymotrypsin inhibitoractivity was highest in the peanut (69.6 CIU/g) but lowestin the collard leaves (48.0 CIU/g). Both trypsin and chymotrypsin inhibitor activities were significantly (p<0.05) reduced by most of the treatments in eitherthe conventional or microwave blanching methods. In the conventional blanching method, trypsin inhibitor activitywas reduced by 0.5, 6.8, 11.9, 9.0 and 19.3 percent in cabbage, collard, turnip, sweet potato and peanut leaves,respectively, when the vegetables were blanched for 2.5 minutes but after blanching for 10 minutes, the trypsininhibitor activity was reduced by 29.7, 34.9, 54.3, 52.3and 65.6 percent in cabbage, collard, turnip, sweet potatoand peanut greens, respectively. For the microwave ovenblanching, trypsin inhibitor activity was reduced by 3.8,3.3, 32.7, 5.0 and 9.5 percent in cabbage, collard, turnip,sweet potato and peanut leaves, respectively when thevegetables were blanched for 30 seconds. When blanched for60 seconds, trypsin inhibitor activity was reduced by 16.2,45.8, 46.2, 51.0 and 42.4 percent in cabbage, collard, turnip, sweet potato and peanut greens, respectively.Similar trends in the reduction of chymotrypsin inhibitoractivity were observed when the vegetables were conventionally blanched for 2.5, 5 and 10 minutes andwhen blanched by microwave oven for 30, 45 and 60 seconds.Based on the results of this study, the vegetables weregood dietary sources of minerals, vitamins, carbohydrateand proteins. Also, blanching was an effective method forreducing the trypsin and chymotripsin inhibitor activitiesin the leafy vegetables, however, further investigation onthe heating times for both conventional and microwaveblanching methods is suggested.     

Almond (<Emphasis Type="Italic">Prunus dulcis</Emphasis> L.) Protein Quality

Three marketing varieties of almonds; Carmel, Mission, and Nonpareil; were analyzed for proximate composition and protein nutritive quality. Moisture, lipids, protein, ash, sugars, and tannins ranges were 3.05-4.33%, 43.37-47.50%, 20.68-23.30%, 3.74-4.56%, 5.35-7.45%, and 0.12-0.18%, respectively. No detectable hemagglutinating and trypsin inhibitory activities were present in Carmel, Mission, and Nonpareil almonds. Amino acid analyses indicated the sulfur amino acids (methionine + cysteine), lysine, and threonine to be the first, second, and third limiting amino acids in almonds when compared to the recommended amino acid pattern for children 2-5-year old. However, compared to the recommended amino acid pattern for adults, sulfur amino acids were the only limiting amino acids in almonds tested. True Protein Digestibility (% TPD) values for Carmel, Mission, and Nonpareil were 88.55 +/- 1.26, 92.25 +/- 1.05, and 82.62 +/- 1.47, respectively. Protein Digestibility Corrected Amino Acid Scoring (PDCAAS) values suggested almond proteins to be of poor nutritional quality.     

Effect of processing on nutrient composition and anti-nutritive substances of African locust bean (Parkia filicoidea) and baobab seed (Adansonia digitata)

The effects of various processing techniques on nutrient composition and anti-nutritional factors in baobab seeds (Adansonia digitata L.) and locust beans (Parkia filicoidea L.) were investigated. The methods used for processing include boiling in water, acid or alkali and fermentation. Using the water treated samples as controls, there were slight decreases in protein and carbohydrate contents of the fermented and alkali-treated meals. However, an increase in extractable oil content was observed in acid, alkali and fermented samples. The alkali treatment appeared to be the most effective method for reducing trypsin inhibitor and tannin contents and has the additional advantage of improving the protein digestibility.     

豆类中胰蛋白酶抑制剂活性测定与初步分析

大豆中主要的抗营养因子是胰蛋白酶抑制剂,在其它食用豆中也有存在。供试大豆中胰蛋白酶抑制剂活性(TIA)最高(20.30～26.30TIU/g),菜豆次之(2.93～6.41TIU/g),蚕豆、豌豆为2.01～2.87及1.66～2.38TIU/g。大豆中抑制剂活性与粗蛋白及粗脂肪之间存在显著负相关。测定结果表明:国内选育的不含SBTI—A_2基因大豆材料,抑制剂总活性为17.40TIU/g,低于其栽培品种亲本21.20～21.60TIU/g。     

半胱胺对鹅胰液分泌及其蛋白酶活性的影响

1 2只装有胰腺—十二指肠长久性瘘管的成年鹅 ,圈养 ,夜间 (2 0∶0 0～ 8∶0 0 )禁食 ,随意饮水。实验采用前后自身对照 ,试验期在日粮中一次性添加半胱胺 (1 0 0mg/kg·BW) ,连续计量 3d对照期和 8d试验期胰液分泌速率并测定其中胰蛋白酶活性。添加半胱胺后 :①胰液连续 7d的分泌速率均极显著高于对照期 ,幅度为 71 2 8%～399 77% ,其中白天升高了 40 80 %～ 456 0 9% ,夜间升高了 1 4 3 74%～ 31 1 42 % ;②第 3d起单位容积胰蛋白酶的活性较对照期极显著升高 ,且变化幅度具有昼夜的差别 ,白天从第 3d、夜间从第 5d显著高于对照 ;③半胱胺使每小时胰液中的胰蛋白酶活性显著升高 ,且白天增加的幅度较夜间大。以上结果提示 :半胱胺能促进鹅胰液的分泌 ,增加胰蛋白酶的分泌总量 ,由此提高了鹅对饲料蛋白质的消化能力 ,以适应机体快速生长时的营养需求。     

改善大豆饼(粕)品质的途径

本文综述了胰蛋白酶抑制因子的抗营养作用,以及使该因子失活、改善大豆饼(粕)品质的主要方法。     

无种皮南瓜籽胰蛋白酶抑制剂的分离纯化与部分性质研究

采用分级盐析和Sephadex G-50的方法分离纯化无种皮南瓜籽胰蛋白酶抑制剂,用BAPNA法进行抑制活性的测定,用SDS-PAGE法测定蛋白质的分子量,用不同的温度处理方法对它的热稳定性进行研究,并对抑制剂的Lys和Cys进行了化学修饰。结果表明在饱和度为60%的硫酸铵作用下,能够沉淀出活性较强的胰蛋白酶抑制剂,其分子量为29 512 Da,并且具有一定热稳定性,在80℃恒温处理1 h仍保持一定的抑制活性。证明了无种皮南瓜籽胰蛋白酶抑制剂是一种分子量较小的,以Lys为活性中心的具有一定热稳定性的蛋白质。     

缺失Kunitz胰蛋白酶抑制剂和脂肪 氧化酶2的大豆新品种中黄31的选育

大豆新品种中黄31是中国农业科学院作物科学研究所利用缺失Kunitz胰蛋白酶抑制剂的高产、优质、 抗花叶病毒病( SMV)的高代材料ti15176作母本,美国引进优良品种Century近等基因系、脂肪氧化酶缺失的优质 材料Century - 2. 3作父本进行有性杂交,采用未变性聚丙烯酰胺凝胶电泳(Native - PAGE)技术及等电聚焦聚丙烯 酰胺凝胶电泳( IEF - PAGE)技术,对杂种后代胰蛋白酶抑制剂( Ti) 、脂肪氧化酶(Lox)进行缺失检测及多年辅助选 择育成。该品种于2005年通过北京市品种审定委员会审定。其突出特点是高产、稳产、优质(蛋白质品质优异% 缺失Ti和Lox2) 、抗病、抗倒、综合性状优良。     

Digestive function and intestinal integrity in Atlantic salmon (Salmo salar) fed kernel meals and protein concentrates made from yellow or narrow-leafed lupins

This study assessed the effects of yellow lupin (Lupinus luteus) and narrow-leafed lupin (L. angustifolius) kernel meals and protein concentrates on the gastrointestinal integrity, capacity for digestive hydrolysis, and digestibility of nutrients in Atlantic salmon. A basal diet (FM) was made from fish meal, wheat, and fish oil. Six additional diets were formulated by replacing 30% of the FM diet with lupin kernel meal made from L. l. cv. Wodjil (LKM), L. a. cv. Belara (BKM), and L. a. cv. Myallie (MKM), lupin protein concentrates made from the same L. l. (LPC) and L. a. cv. M (MPC), or extracted soybean meal (SBM). All diets were extruded. Each diet was fed to three groups of 176 g salmon kept in 1 m² tanks with 5.6 °C saltwater for 3 weeks prior to sampling of blood, intestinal organs, digesta, and faeces. Inclusion of lupin meals in the diets resulted in harder and more condensed feed particles. Ulcer-like lesions were observed in the stomach of fish from all feeding groups, and this was worsened by lupin in the diet, but did not appear to be pellet hardness related. No consistent altered morphology was observed in the distal intestine (DI) of fish fed the FM and lupin diets, while the DI of fish fed SBM showed consistent and typical soybean meal-induced pathomorphological changes. Plasma cholesterol was higher when feeding MKM and LKM than when feeding FM, MPC, and LPC, with intermediate levels when feeding BKM and SBM. Feeding LKM and LPC resulted in a higher weight of the GIT when related to body weight. Trypsin activity and bile acid concentration were generally higher in digesta from the pyloric (PI) and mid (MI) intestine when feeding FM and lupin diets than when feeding SBM, while the opposite was seen for trypsin activity in digesta from DI. There were no effects of diet on leucine aminopeptidase (LAP) and maltase activity in PI and MI, but in DI the activity of these brush border enzymes were significantly lowered when feeding SBM. SBM in the diet resulted in watery faeces and lowered apparent digestibility of lipid, but this was not observed when feeding the lupin diets. To conclude, the tested lupin kernel meals and protein concentrates did not alter the intestinal function in Atlantic salmon when included at 30% of the diet. Dietary lupin was, however, involved in the worsening of ulcer-like gastric lesions.