Functional properties of fenugreek (Trigonella foenum graecum) protein concentrate

Proximate composition and physicochemical properties of a protein concentrate prepared from fenugreek seed were determined. The effects of pH and/or NaCl concentration on these properties were investigated. The protein content of fenugreek was found to be 28.4%. The crude fibre content was 9.3% and crude fat was 7.1%. The minimum protein solubility was observed at pH 4.5, which was 18.5%, while maximum protein solubility was observed at pH 11, which was 91.3%.     

Changes in carbohydrates of germinating fenugreek seeds (Trigonella foenum graecum L.)

The effect of germination at 25 °C for 96 h in the dark on the carbohydrates of fenugreek seed was investigated. Reducing, total reducing, non-reducing sugar, and pentosan contents increased. Polysaccharides estimated as starch decreased. Fenugreek contained mucilage (18%), which decreased considerably during germination. The decline in mucilage content was accompanied by a drop in galactan content. Total pectic content did not change, but there was a decline in the high methoxy pectin content, while protopectin, and the low methoxy pectate salts of calcium and magnesium increased. The 70% ethanol soluble carboydrates were chromatographically determined. Fenugreek seeds contained sucrose, raffinose, stachyose, and an unidentified sugar ( I ). A marked increase in sucrose content was observed after germination. Raffinose, stachyose and the unknown sugar ( I ) decreased, while another unknown ( II ) appeared. The two unknown sugars may be members of the raffinose family. Maltose and fructose appeared in measurable amounts after germination.     

Effect of germination on the nitrogenous constituents,protein fractions, in vitro digestibility and antinutritional factors of fenugreek seeds (trigonella foenum graecum L.)

This study was designed to determine the effect of germination on nitrogenous constituents, protein fractions, in vitro digestibility and antinutritional factors (namely trypsin inhibitor and haemagglutinin) of the Egyptian fenugreek seeds Geiza 2 variety. After 96 h of germination, there was 18% decrease in the dry weight of seeds, a slight increase of total nitrogen (TN), a decrease of protein nitrogen (PN) and a marked increase of both non-protein nitrogen (NPN) and free amino acid nitrogen (FAAN). Non-protein nitrogen other than FAAN, amido nitrogen and ammonia nitrogen also increased. The protein fractions (namely albumin, globulin, prolamin and glutelin) were separated according to their solubilities in different solvents. The ratio between the four protein fractions in ungerminated seeds was 4:3.5:2.8:1 and became 2:6.5:7.7:1 after germination as calculated on the basis of their PN.Trypsin inhibitor activity per gramme of fenugreek was found to be higher by 66% in germinated fenugreek than ungerminated seeds. Both ungerminated and germinated fenugreek was found devoid of the haemagglutinin activity.Germination resulted in a slight increase in pancreatic digestibility, 33.7% decrease in digestibility by pepsin followed by pancreatin, while a small decrease was found in peptic digestibility.     

Starch–fenugreek (Trigonella foenum-graecum L.) polysaccharide interactions in pure and soup systems

The effect of replacement of varying levels of a fenugreek polysaccharide (FP) product (0.1–0.9%) on 5% wt/wt corn starch cream soups and pure starch systems was investigated. Pasting, textural and viscoelastic characteristics along with granule size and sensory properties were determined. Significant changes were revealed with increasing FP replacement, with the effects being more pronounced on the soup formulations compared to the effects on pure starch/fenugreek systems.     

Chemical and amino acid composition of fenugreek seeds grown in Sudan

The proximate chemical composition and amino acid profile of fenugreek seeds grown in Sudan were determined. The seeds are rich in leucine, valine, lysine and phenylalanine. Manganese, magnesium, zinc and copper contents are reported for the first time.     

Characterization,amino acid composition and in vitro digestibility of hemp (Cannabis sativa L.) proteins

The protein constituents and thermal properties of hemp (Cannabis sativa L.) protein isolate (HPI) as well as 11S- and 7S-rich HPIs (HPI-11S and HPI-7S) were characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and different scanning calorimetry (DSC), and their amino acid composition and in vitro digestibility were also evaluated, as compared to soy protein isolate (SPI). SDS-PAGE analysis showed that the edestin (consisting of acidic and basic subunits, AS and BS) was the main protein component for HPI and HPI-11S, while HPI-7S was composed of the BS of edestin and a subunit of about 4.8 kDa. DSC analysis characterized thermal transition of the edestin component and the possible present form of different subunits. Except lysine and sulfur-containing amino acids, the essential amino acids of various HPIs met the suggested requirements of FAO/WHO for 2–5 year old infants. The proportion of essential amino acids to the total amino acids (E/T) for HPI (as well as HPI-11S) was significantly higher than that of SPI. In an in vitro digestion model, various protein constituents of various HPIs were much easily digested by pepsin plus trypsin, to release oligo-peptides with molecular weight less than 10.0 kDa (under reduced condition). Only after pepsin digestion, in vitro digestibility of HPIs was comparable to that of SPI, however after pepsin plus trypsin digestion, the digestibility (88–91%) was significantly higher than that (71%) of SPI (P < 0.05). These results suggest that the protein isolates from hempseed are much more nutritional in amino acid nutrition and easily digestible than SPI, and can be utilized as a good source of protein nutrition for human consumption.     

Chemical composition,amino acid content and protein quality of Canavalia spp. seeds

Canavalia ensiformis is a grain legume that offers good possibilities for its use, but reports on its chemical composition and nutritive quality are not readily available. This study presents chemical and nutritional data on C. ensiformis, C. gladiata and C. maritima grains. The three species varied in protein content mainly because of differences in crude fibre content. Protein varied from 26.9 to 22.4%, and crude fibre varied from 8.5 to 17.3%. This was due to differences in seed-coat percentage. The amino acid content in C. ensiformis and C. gladiata was essentially the same, and both were deficient in sulphur-containing amino acids but rich in lysine. Pressure cooking and roasting reduced lysine levels. Mineral content in the three species was essentially the same, with high potassium levels as is the case with most food legumes. Feeding trials indicated low nutritional quality for the raw grain, which was significantly improved by pressure cooking and roasting. Protein digestibility was 47.9%, and cooked and roasted samples had 76.4 and 78.7%, respectively. Both C. ensiformis and C. gladiata had the same protein quality (PER = 1.24), and it was significantly improved with methionine supplementation.     

苦杏仁蛋白提取工艺优化及氨基酸分析

为了综合开发和利用苦杏仁资源,采用二次回归正交旋转组合设计,优化了碱溶酸沉法制备杏仁蛋白的工艺,并分析了其氨基酸组成。结果表明,杏仁蛋白等电点为pH4．0;杏仁蛋白的优化提取工艺参数为：pH10．0,提取温度45℃,料液比1：13（m／V）,提取时间30min,连续提取2次,在此条件下杏仁蛋白提取率为87．58％,杏仁蛋白中粗蛋白质量分数为71．86％。苦杏仁蛋白的氨基酸组成种类齐全,必需氨基酸含量较高,是一类较优质的植物蛋白质资源,有待深度开发。     

Antioxidant properties and quantitative UPLC-MS analysis of phenolic compounds from extracts of fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit

Freeze-dried fenugreek (Trigonella foenum-graecum) seeds and bitter melon (Momordica charantia) fruit were extracted sequentially using non-polar to polar solvents, with further separation carried out on polar extracts by molecular weight cut off dialysis. The fenugreek ethyl acetate crude extract (FGE3) demonstrated the highest antioxidant activity, in terms of Trolox Equivalents (TE), for both the DPPH (35.338 ± 0.908 mg TE/g) and FRAP (77.352 ± 0.627 mg TE/g) assays. This extract also contained the highest phenolic content, in terms of Gallic Acid Equivalents (GAE) (106.316 ± 0.377 mg GAE/g). Despite having considerably lower antioxidant activity than fenugreek, the highest antioxidant activities for bitter fruit were observed in the hexane (BME1) and methanol hydrophilic < 3.5 kDa dialysed (BME4 < 3.5 kDa) extracts, while the highest phenolic content was found in the methanol hydrophilic > 3.5 kDa (BME4 > 3.5 kDa) dialysed extract. UPLC-MS was used to quantify 18 phenolic compounds from fenugreek and 13 from bitter melon in active crude extracts. The flavonoids apigenin-7-O-glycoside (1955.55 ng/mg) and luteolin-7-O-glycoside (725.50 ng/mg) were the most abundant compounds in FGE3, while bitter melon extracts contained only small amounts of mainly phenolic acids. A further 5 fenugreek and 1 bitter melon compounds were identified in trace amounts from the same extracts, respectively.     

Chemical,amino acid and fatty acid composition of Sterculia urens L. seed

The chemical, amino acid and fatty acid compositions of Sterculia urens seeds are reported. The cotyledons were found to be rich in protein (30.88%) and lipids (39.2%). The major amino acids in defatted Sterculia urens cotyledon flour (DSCF) were determined as glutamic acid, arginine and aspartic acid. Cysteine, methionine, tyrosine and histidine were observed in minor quantities. The ratio of essential to non-essential amino acids was observed to be 0.45. Among the essential amino acids, isoleucine was found to be higher than the reported FAO/WHO requirements. The GC-FID and GC–MS analysis revealed that the major fatty acids of the total lipid were stearic acid (31.72%), linoleic acid (28.83%) and palmitic acid (26.79%). Eicosadienoic acid (4.98%) and eicosatrienoic acid (2.96%) were also found in the total lipid.     

Inhibitors of human and bovine trypsin and chymotrypsin in fenugreek (Trigonellafoenum-graecum L.) seeds

Summary The reaction between the three Bowman-Birk proteinase inhibitors isolated from fenugreek seeds (TFI-B2, TFI-N2 and TFI-A8) and the human and bovine proteinases was investigated by studying the complexes formed and their properties. TFI-B2, the Lys-Leu trypsin chymotrypsin inhibitor, can bind 1.9 mol human trypsin (HT), 1.3 mol bovine trypsin (BT) and/or 0.4 mol human (HCT) or bovine (BCT) chymotrypsin per mole of inhibitor. HT was bound at the two reactive sites and BT mainly at the lysine-containing trypsin-reactive site, whereas HCT and BCT were only bound at the leucinecontaining chymotrypsin-reactive site. TFI-N2, the Arg-Leu trypsin chymotrypsin inhibitor, could bind 1 mol BT and BCT, but 1.3 mol HT and 1.2 mol HCT per mole of inhibitor. In addition to the usual binding, the human enzymes could also be bound at the respective wrong reactive site. TFI-A8, the Arg-Arg trypsin inhibitor, binds 2 mol HT or BT per mole of inhibitor at the two trypsin-reactive sites, whereas HCT and BCT (about 0.2 mol/mol) are bound to one of the two wrong reactive sites.

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Reaktion der Bockshornklee-Proteinaseinhibitoren mit Human- und Rindertrypsin und -chymotrypsin

Zusammenfassung Die Reaktion zwischen den drei aus Bockshornkleesamen isolierten Bowman-Birk-Inhibitoren, TFI-B2, TFI-N2 und TFI-A8, und den Human- und Rinderproteinasen, Humantrypsin (HT), Rindertrypsin (RT), Humanchymotrypsin (HCT) und Rinderchymotrypsin (RCT), wurde durch Nachweis der gebildeten Komplexe und Ermittlung ihrer Eigenschaften untersucht. TFI-B2, der Lys-Leu-Trypsin-Chymotrypsin-Inhibitor, kann pro Mol 1,9 Mol HT, 1,3 Mol BT und/oder 0,4 Mol HCT oder BCT binden. HT wird an beide reaktive Zentren und BT hauptsächlich an das Lysin enthaltende trypsinspezifische reaktive Zentrum gebunden, während HCT und BCT nur an das Leucin enthaltende chymotrypsinspezifische reaktive Zentrum gebunden werden. TFI-N2, der Arg-Leu-Trypsin-Chymotrypsin-Inhibitor, kann pro Mol ein Mol BT und BCT, aber 1,3 Mol HT und 1,2 Mol HCT binden. Zusätzlich zum üblichen Verhalten können die Humanenzyme auch an das jeweilige falsche reaktive Zentrum gebunden werden. TFI-A8, der Arg-Arg-Trypsin-Inhibitor, bindet pro Mol 2 Mol HT oder BT an die beiden trypsinreaktiven Zentren, während HCT und BCT (ca. 0,2 Mol/Mol) an eines der beiden falschen reaktiven Zentren gebunden werden.

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This study was presented in part at EURO FOOD CHEM V, 27–29 September 1989, Versailles, France [1]     

Biochemical studies of some non-conventional sources of protein. Part 5. Extraction and characterization of protein from fenugreek seed (Trigonella foenum L.)

Protein concentrates were prepared from fenugreek seeds by extraction with distilled water, salt solution and alkaline solution. Alkaline solution resulted in the highest extraction yield (82%). The protein concentrate has a good digestibility (over 90%) as determined by in vitro enzymatic method. The protein is rich in lysine (6.51%) but poor in sulphur-containing amino acids such as methionine (0.71%), cystine (1.09%) and tryptophan (1.03%).     

Polyphenol oxidase activity,phenolic acid composition and browning in cashew apple (Anacardium occidentale, L.) after processing

This study describes the extraction and characterisation of cashew apple polyphenol oxidase (PPO) and the effect of wounding on cashew apple phenolic acid composition, PPO activity and fruit browning. Purification factor was 59 at 95% (NH₄)₂SO₄ saturation. For PPO activity, the optimal substrate was catechol and the optimum pH was 6.5. PPO K_m and V_max values were 18.8 mM and 13.6 U min⁻¹ ml⁻¹, respectively. Ascorbic acid, citric acid, sodium sulphite and sodium metabisulphite decreased PPO activity, while sodium chloride increased PPO activity. Wounding at 2 °C and 27 °C for 24 h increased PPO activity but storage at 40 °C reduced PPO activity. Gallic acid, protocatechuic acid and cinnamic acid (free and conjugate) were identified in cashew apple juice. Cutting and subsequent storage at 40 °C hydrolysed cinnamic acid. 5-Hydroxymethylfurfural content in cashew apple juice increased after injury and storage at higher temperatures, indicating non-enzymatic browning.     

Extrusion of a hard-to-cook bean (Phaseolus vulgaris L.) and quality protein maize (Zea mays L.) flour blend

Heated extrusion was tested as an alternative process for incorporating “hard-to-cook” beans into food products. A 3² factorial design was used to evaluate extrusion conditions for a 40/60 (w/w) blend of “hard-to-cook” beans and quality protein maize. Tested extrusion variables were temperature (155, 170 and 185 °C) and moisture content (15.5, 17.5 and 19.5 g/100 g). Screw speed was fixed at 130 rpm. The extrudates obtained at 155 and 170 °C with 15.5% moisture had the best physical characteristics and were chosen for comparative analysis of nutritional changes between the unprocessed “hard-to-cook” bean/quality protein maize flour blend and the resulting extrudates. In vitro protein digestibility was higher in the extrudates (80%) than in the flour blend (76%). In vitro starch digestibility was higher at 155 °C (89%) and 170 °C (92%) than in the flour blend (12%). Processing conditions decreased dietary fibre content by 38% at 155 °C and 44% at 170 °C.     

Antioxidant activity and phenolic composition of sumac (Rhus coriaria L.) extracts

Antioxidant activity and phenolic compounds of sumac extracts were investigated. Sumac was extracted in methanol and subjected to solvent–solvent partitioning to yield two fractions as ethyl acetate and aqueous. Methanol extract was further fractioned over Sephadex LH-20 column. Antioxidant activity of extracts and fractions were screened using ferric thiocyanate and DPPH radical scavenging methods. Phenolic composition of active fraction(s) was determined by HPLC–MS systems. Those fractions which exhibited strong antioxidant activity were rich in anthocyanins and hydrolysable tannins. While gallic acid was the main phenolic acid in the extracts, anthocyanin fraction contained cyanidin, peonidin, pelargonidin, petunidin, and delphinidin glucosides and coumarates. Pentagalloyl glucose was abundant in the hydrolysable tannin fraction. Effective scavenging concentration (EC₅₀) on DPPH radical was 0.70 μg/mL both in ethyl acetate and tannin fractions, and 5.33 μg/mL in anthocyanin rich fraction. Same extracts and fractions showed moderate lipid peroxidation inhibition effect compared with the synthetic antioxidants. The findings demonstrate that sumac can be used as a natural antioxidant.     

Nutritional and amino acid contents of differently treated Roselle (Hibiscus sabdariffa L.) seeds

The effects of sun-drying and boiling sun-drying on the nutritional composition of Roselle (Hibiscus sabdariffa L.) seeds, grown from Malaysia, were investigated. The treatments were raw freeze-dried Roselle seeds (RRS), sun dried Roselle seeds (DRS) and boiled sun-dried Roselle seeds (BRS). Protein, lipids and dietary fibre were found to be high in all the treatments. The seeds, regarded as by-product of Roselle processing had 57.3% moisture. Raw freeze-dried, sun dried and boiled sun-dried seeds contained 6.81%, 9.9% and 9.8% moisture; 35.4%, 33.5% and 30.6% protein; 27.2%, 22.1% and 29.6% lipids; 2.3%, 13.0% and 4.0% available carbohydrate; 25.5%, 18.3%, and 19.2% total dietary fibre; and 7.4%, 7.5% and 6.6% ash, respectively. The carbohydrate, protein, lipids and moisture of RRS were significantly different (p < 0.05) from DRS and BRS. The predominant minerals in Roselle seeds were potassium (99–109 mg/100 g), magnesium (26–28 mg/100 g) and calcium (24–31 mg/100 g). The total dietary fibre of the seeds was within the acceptable range, with soluble and insoluble fibre ratios ranging from 1.2 to 3.3. The study detected 17 essential and non-essential amino acids. The seeds were rich in lysine (14–15 g/100 g), arginine (30–35 g/100 g), leucine (15.4–18.6 g/100 g), phenylalanine (11–12 g/100 g) and glutamic acid (21–24 g/100 g). The study indicated that Roselle seeds may serve as a potential source of functional ingredients.     

10个品种核桃油品质比较

为研究不同解冻方式对冷冻脱衣核桃仁品质的影响,以温水浸泡去皮的冷冻脱衣核桃仁为材料,对室温空气解冻、微波解冻、4 ℃冷藏解冻和室温超声解冻后核桃仁的色值、质构、游离氨基酸、维生素E（V_E）、不饱和脂肪酸、酸败指标、挥发性成分和显微组织结构进行了测定。结果表明,微波解冻的脱衣核桃仁中游离氨基酸总量、V_E和不饱和脂肪酸等营养物质含量较高,烘烤类香气较浓郁,但核仁色泽变暗,油脂氧化严重,细胞之间孔隙较大;室温空气解冻后核桃仁色泽最差,且氧化哈败程度严重;4 ℃冷藏解冻和室温超声解冻下核仁亮度较高,质地保持较好,游离氨基酸总量显著（P<0.05） 高于其它解冻方式,不饱和脂肪酸含量较高,仅有轻度酸败,贮藏细胞均匀性较好。综上,4 ℃冷藏解冻和室温超声解冻能较好地减轻解冻过程的油脂氧化,保留色泽和营养,保证脱衣核桃仁的解冻品质。