Proteolytic activity,amino acid composition and protein quality of germinating fenugreek seeds (Trigonella foenum graecum L.)

This study determined the changes in proteolytic activity and trypsin inhibitor, due to germination for 120 h, and their relationships to amino acid content and protein quality. The activities of cas-ase, Hb-ase, and BAPA-ase, as well as the trypsin inhibitor of the fenugreek, increased as germination proceeded. Glutamic and aspartic acids were the richest amino acids in fenugreek seeds, followed by leucine, arginine, lysine and proline. After germination, the contents of aspartic acid, phenylalanine, tyrosine, threonine, tryptophan and valine increased, while those of glutamic acid, proline and four of the essential amino acids decreased. All the free amino acids increased after germination, while glycine decreased. Cystine, tryptophan and proline originated in a free form after germination. The chemical score, based on the essential amino acid pattern of whole egg protein, for fenugreek seeds, showed a marked decrease (21%) after germination. The in vitro pepsin, followed by pancreatin digestion, showed a slight increase for the germinated seeds. Germination of seeds lowered the C-PER, a result which indicates that the protein quality decreased.     

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%.     

Effect of soaking and hydrothermal processing methods on the levels of antinutrients and in vitro protein digestibility of Bauhinia purpurea L. seeds

The effects of various domestic processing methods such as soaking, cooking and autoclaving on the levels of certain antinutritional factors and in vitro protein digestibility of seeds of Bauhinia purpurea L., an underutilised legume collected from South India, were investigated. The raw seeds were found to contain antinutritional factors like total free phenolics (2.75 g/100 g), tannins (2.35 g/100 g), phytic acid (692 mg/100 g) and flatulence factors, raffinose (0.54 g/100 g), stachyose (1.17 g/100 g) and verbascose (0.95 g/100 g). Soaking the seeds in distilled water caused maximum reduction in the phytic acid content (37%), whereas soaking in NaHCO₃ solution reduced significant levels of phenolics and tannins (72% and 78%, respectively). A reduction in the levels of oligosaccharides (raffinose by 63%, stachyose by 42% and verbascose by 79%) was observed during cooking. Of the attempted treatments, autoclaving appeared to be most effective in reducing levels of all the investigated antinutrients, except phytic acid, and also improved the in vitro protein digestibility of B. purpurea seeds.     

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.     

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 processing on antinutrients and in vitro protein digestibility of kidney bean (Phaseolus vulgaris L.) varieties grown in East Africa

The effects of hydration, autoclaving, germination, cooking and their combinations, on the reduction/elimination of antinutrients, flatus-producing compounds and the improvement of in vitro protein digestibility of three selected Phaseolus vulgaris varieties were investigated. Reduction in the amount of total α-galactosides was attained by employing hydration process and was due to the differential solubility of the individual oligosaccharides and their diffusion rates. Due to their heat-sensitive nature, saponins, trypsin inhibitors and phytohaemagglutinins, diminished drastically to undetectable amounts when heating processes (cooking and autoclaving) were employed. Hydration and germination processes were less effective in reducing trypsin inhibitors, saponins and phytohaemagglutinins as compared with cooking/autoclaving processes. Germination process reduced stachyose, raffinose, phytic acid and tannins which was due to metabolic activity. The combination of germination followed by autoclaving processes yielded the most promising result in this study. The bean variety Roba exhibited better protein digestibility on processing and thus has high potential to be used as a raw material for the manufacturing of value-added products.     

Effect of heat,rutin and disulfide bond reduction on in vitro pepsin digestibility of Chinese tartary buckwheat protein fractions

Protein fractions (albumin, globulin, prolamin and glutelin) were extracted from defatted tartary buckwheat flour. The in vitro pepsin digestibilities of the four protein fractions were different, and albumin was more susceptible to pepsin hydrolysis. The native structure of the four protein fractions may be destroyed by heat treatment, and the digestibilities were all improved significantly (P < 0.05). Adding rutin to the digestion mixture of the four fractions did not cause a decrease in pepsin digestibility, although it did cause a significant increase in certain instances (P < 0.05). Treatment with β-mercaptoethanol (2-ME) only caused a higher initial proteolysis rate and did not increase the final digestibility distinctly except for prolamin. After pepsin digestion, the remaining proteins of unhydrolyzed albumin, globulin, prolamin and glutelin (untreated) shared some similarities. They also exhibited a minor band at 20,000 Da and a broad band at 10,000–14,000 Da.     

A study of the in vitro protein digestibility of indica and japonica cultivars

Protein digestibility was determined in 18 indica and japonica raw milled rices using an in vitro pH-drop method with three- or four-enzyme system. Similar protein digestibility was found between indica and japonica rices, which is in agreement with the in vivo digestibilities in human. Cooking improved protein digestibility in the four-enzyme assay, while reducing agents exhibited apparent inhibition in multienzyme digestibility of indica and japonica rices. A significant correlation was detected between protein content and the estimates of digestibility, whereas no significant correlation was found between amylose content and digestibility estimates. SDS–PAGE analysis showed a significant difference in the degradation extent of prolamin between multienzyme and pepsin digestion, which might contribute to the inconsistence between results of this study and previous findings that in vitro protein digestibility of japonica rice was higher than that of indica rice. In addition, our results supported the previous report that waxy gene product level is not a major determinant of protein digestibility in milled rice.     

The in vitro and in vivo antioxidant properties of seabuckthorn (Hippophae rhamnoides L.) seed oil

The antioxidant capacity of seabuckthorn (Hippophae rhamnoides L.) seed oil was investigated with a number of established in vitro assays and in an in vivo study of carbon tetrachloride (CCl₄)-induced oxidative stress in mice. The results showed that DPPH radical scavenging activity, ferrous ion chelating activity, reducing power and inhibition of lipid peroxidation activity all increased with increasing concentrations of seabuckthorn seed oil. Moreover, the EC₅₀ values of seabuckthorn seed oil from the hydrogen peroxide, superoxide radical, hydroxyl radical scavenging assays were 2.63, 2.16 and 0.77 mg/ml, respectively. In the in vivo study, seabuckthorn seed oil inhibited the toxicity of CCl₄, as seen from the significantly increased activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase. The GSH content in the liver was also increased, whereas hepatic malondialdehyde was reduced. Taken together, these results clearly indicate that seabuckthorn seed oil has significant potential as a natural antioxidant agent.     

Effect of endosperm type on texture and in vitro starch digestibility of maize tortillas

Tortilla is the main staple of Mexico and it is made using diverse maize varieties, which have different endosperm types. Three maize varieties with vitreous, intermediate and floury endosperms were used. Texture and starch digestibility were evaluated in freshly prepared and stored tortillas for 24, 48 and 72 h. Tortilla made with maize of vitreous endosperm had the highest force to rupture and the lowest distance of elongation, indicating more rigid texture. Stored tortillas had lower available starch content and higher effect was shown by tortilla of vitreous endosperm, pattern that agrees with the higher increase in the resistant starch content with the storage time. Fresh tortilla of floury endosperm showed the highest hydrolysis rate during the first 15 min followed by tortillas of intermediate and vitreous endosperms. Starch hydrolysis values decreased when storage time increased, in agreement with the resistant starch content in the stored tortillas. At the longest storage time (72 h) tortilla of floury endosperm presented higher hydrolysis rate, followed by tortilla of intermediate and vitreous endosperms. The endosperm type plays an important role in the textural and starch digestibility of fresh and stored tortillas.     

Antioxidant activities of malt extract from barley (Hordeum vulgare L.) toward various oxidative stress in vitro and in vivo

The antioxidant activities of malt extract from barley were evaluated by various methods in vitro and in vivo. Scavenging effects on the hydroxyl and superoxide radicals, and protection against reactive oxygen species induced lipid, protein and DNA damage were evaluated. The d-galactose induced mouse aging model was used to evaluate ability of malt extract to behave as an antioxidant in vivo. The extract exhibited high antioxidant activities both in vitro and in vivo, evidenced by its ability to scavenge hydroxyl- and superoxide-radicals, high reducing power, and protection against biological macromolecular oxidative damage. Furthermore, malt extract prevented the decrease of antioxidant enzyme activities, decreased liver and brain malondialodehyde levels and carbonyl content, and improved total antioxidant capability in d-galactose-treated mice. In conclusion, these results demonstrate potential antioxidant activities and antiaging effect of malt, providing scientific support for the empirical use of malt as an antioxidant for diseases caused by reactive oxygen species.     

Effect of non-starch polysaccharides on the in vitro digestibility and rheological properties of rice starch gel

The starch digestibility and rheological properties of gels were evaluated in the presence of three non-starch polysaccharides (agar, xanthan gum and konjac glucomannan) with rice starch. Each polysaccharide was added to 30% (w/w) rice starch suspension at defined concentrations and starch gels were prepared. The extent of starch gel digestibility was determined by an in vitro method and rheological properties by a dynamic oscillatory test and a compression test. The added polysaccharides suppressed starch hydrolysis in the gels compared with the control, and a concentration dependency of this suppressive effect was observed. Adding agar and xanthan gum increased the storage shear modulus (G′) of starch gels, while adding konjac glucomannan decreased G′ values. The results indicate that the suppressive effect of non-starch polysaccharides on starch digestibility appears to be not only due to the rigidity of the gel, but also the interaction between starch and non-starch polysaccharides.     

Changes in gross chemical composition with emphasis on lipid and protein fractions during germination of fenugreek seeds

Germination of fenugreek seeds for 3 and 5 days increased moisture, crude protein, crude fibre, non-protein nitrogen and ash contents, but total lipids and carbohydrates were decreased. Marked increases of Na and P, as well as Mg and Zn were observed. Triacylglycerols decreased continuously and this was accompanied by an increase in free fatty acids, monoglycerides, sterolesters and polar lipids. Albumin was the major protein fraction followed by globulin, glutelin and prolamin. Germination increased glutelin and non-protein nitrogen; the other fractions were decreased. The protein in vitro digestibility was improved after germination. PAGE showed a marked dissociation of albumin and globulin fractions after germination.     

Effect of citric acid deamidation on in vitro digestibility and antioxidant properties of wheat gluten

The effects of citric acid deamidation on the physiochemical properties of wheat gluten were investigated. In vitro digestion was carried out to determine changes of molecular weight distribution, amino acids composition and antioxidant efficacy of wheat gluten hydrolysates. Results indicated that citric acid deamidation significantly increased gluten solubility and surface hydrophobicity, at a neutral pH. Deamidation induced molecular weight distribution change of gluten with little proteolysis. Results from FTIR indicated that the α-helix and β-turn of deamidated gluten increased accompanied by a decrease of the β-sheet structure. After deamidation, in vitro pepsin digestibility of wheat gluten decreased, while in vitro pancreatin digestibility increased. The oxygen radical absorbance capacity (ORAC) activity of the in vitro digests decreased with increase of deamidation time. The high Lys and total essential AAs amounts in the final digests suggested that the nutritional values of wheat gluten after deamidation might be enhanced.     

Chemical composition and in vitro antioxidative activity of a lemon balm (Melissa officinalis L.) extract

The leaf material of lemon balm (Melissa officinalis L.) was extracted with 450 ml/l aqueous ethanol by medium pressure liquid-solid extraction. The total phenolic content of the extract was estimated as gallic acid equivalents by Folin-Ciocalteu reagent method and a qualitative-quantitative compositional analysis was carried out using high performance liquid chromatography coupled with photodiode array detection. The lemon balm extract contained hydroxycinnamic acid derivatives and flavonoids with caffeic acid, m-coumaric acid, eriodictyol-7-O-glucoside, naringin, hesperidin, rosmarinic acid, naringenin, hesperetin being identified based on their chromatographic behaviour and spectral characteristics. The extract was also investigated for potential in vitro antioxidant properties in iron(III) reduction, iron(II) chelation, 1,1-diphenyl-2-picrylhydrazyl, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonate), superoxide anion and nitric oxide free-radical scavenging, and inhibition of β-carotene-linoleic acid bleaching assays. The extract demonstrated antioxidant activity in all the assays. However, it was not as potent as the positive controls except in the β-carotene-linoleic acid bleaching assay, where its activity was superior to that of gallic and caffeic acids and statistically indistinguishable from quercetin and BHA. The exceptionally high antioxidant activity and the fact that this assay is of biological relevance warrants further investigation of lemon balm extract in ex vivo and in vivo models of oxidative stress.     

Phenolic profiles of in vivo and in vitro grown Coriandrum sativum L.

Coriandrum sativum L. is a source of a variety of polyphenols and other phytochemicals, related to its high antioxidant activity and to its use for indigestion, rheumatism, and prevention of lipid peroxidation damage. Plant cell cultures are a means to study or to produce some active metabolites, such as polyphenols. This technique was applied to the investigation of coriander, and a detailed analysis of individual polyphenols in vivo and in vitro grown samples was performed. The in vivo vegetative parts showed quercetin derivatives as the main flavonoids and quercetin-3-O-rutinoside (3296 mg/kg dw) was the main polyphenol found in this part of coriander. The fruits revealed only phenolic acids and derivatives, caffeoyl N-tryptophan hexoside (45.33 mg/kg dw) being the most abundant phenolic derivative. In vitro samples also gave a high diversity of polyphenols, being C-glycosylated apigenin (2983 mg/kg dw) the main compound. Anthocyanins were only found in clone A, which was certainly related to its purple pigmentation, and peonidin-3-O-feruloylglucoside-5-O-glucoside was the major anthocyanin found (1.70 μg/kg dw). In vitro culture can be used to explore new industrial, pharmaceutical, and medicinal potentialities, such as the production of secondary metabolites like flavonoids.     

Levels of nutritional constituents and antinutritional factors in black gram (Vigna mungo L. Hepper)

A study was conducted on nutritional constituents (total sugars, total proteins, total lipids and starch content) and antinutritional factors such as phenolic compounds, tannins, saponins, phytic acid, trypsin inhibitors and enzymes related to them such as acid- and alkaline phosphatases, ??-galactosidase in eleven recommended cultivars and twenty one advance breeding lines of black gram (Vigna mungo L. Hepper) with an aim to identify genotypes containing high nutritional quality and low antinutritional content. The average content of starch, total soluble sugars, proteins and lipids was around 43.5, 4.84, 22.0 and 1.1%, respectively. Seven genotypes had higher levels of bound fructose contributed by sucrose and raffinose series oligosaccharides. A significant positive correlation was observed among total phenols, o-dihydroxy phenols and flavonols; and among trypsin inhibitors and saponins. The content of phytic acid and activity of trypsin inhibitors showed significant variation among these genotypes. However, not much variation was observed in the content of tannins and saponins. Activities of ??-galactosidase, acid- and alkaline phosphatase were found to be related to the content of bound fructose of raffinose series oligosaccharides and phytic acid respectively. Genotypes having higher activity of these enzymes showed lower content of these antinutritional factors. The results showed that the observed diversity in developed cultivars and advance breeding lines could be further used by plant breeders.     

Impact of germination time and type of illumination on carotenoidcontent,protein solubility and in vitro protein digestibility of chickpea(Cicer arietinum L.) sprouts

Sprouts have been reported to be nutritionally superior to their respective seeds with higher levels of nutrients and lower amounts of antinutrients. Significant differences occur in these nutrients and antinutrients with germination under different types of illumination. This paper reports the impact of germination conditions on changes in β-carotene content, protein solubility and in vitro protein digestibility of chickpea sprouts. The influence of germination time, type of illumination and their interaction on β-carotene content, protein solubility and in vitro protein digestibility of chickpea sprouts was highly significant (p < 0.01). Highest value for β-carotene were observed for sprouts germinated under yellow light for 72 h (131.74 mg 100 g⁻¹) and lowest for blue light group after 120 h germination. Sprouts of irradiated group had overall higher content of β-carotene throughout germination period. Protein solubility was also higher for sprouts of irradiated group and green illumination group after 120 h germination. Sprouts of irradiated group had highest value for% in vitro protein digestibility after 96 h germination followed by the same group after 120 h germination. It is inferred from the study that irradiation of chickpea seed prior to germination improved the β-carotene content, protein solubility and in vitro protein digestibility of chickpea sprouts.     

Influence of non-starch polysaccharides on the in vitro digestibility and viscosity of starch suspensions

The effects of adding non-starch polysaccharides (xanthan gum, guar gum, konjac glucomannan, and pectin) on the starch digestibility and viscosity of raw starch suspensions in a mixed system were determined. Each type of polysaccharide was added to high-amylose corn starch suspensions at defined concentrations. High-amylose rice starch suspensions mixed with xanthan and guar gum were prepared for comparison. The extent of starch digestibility was determined by an in vitro method, and the glucose diffusibility from the dialysis tube in the presence of polysaccharides was measured. The added polysaccharides were observed to decrease the starch digestibility in a mixed system. When compared at the same concentration, xanthan gum showed the most pronounced suppressive effect on starch digestibility and glucose diffusibility from the dialysis tube. The addition of polysaccharides increased the viscosity of the starch suspension. Significant relations were found between the extent of starch digestibility and the apparent viscosity at low shear rate.