Legumes seed storage proteins characterization by SDS-PAGE and Lab-on-a-Chip electrophoresis

Legume Seed Protein Digestibility as Influenced by Traditional and Emerging Physical Processing Technologies

The increased consumption of legume seeds as a strategy for enhancing food security, reducing malnutrition, and improving health outcomes on a global scale remains an ongoing subject of profound research interest. Legume seed proteins are rich in their dietary protein contents. However, coexisting with these proteins in the seed matrix are other components that inhibit protein digestibility. Thus, improving access to legume proteins often depends on the neutralisation of these inhibitors, which are collectively described as antinutrients or antinutritional factors. The determination of protein quality, which typically involves evaluating protein digestibility and essential amino acid content, is assessed using various methods, such as in vitro simulated gastrointestinal digestibility, protein digestibility-corrected amino acid score (IV-PDCAAS), and digestible indispensable amino acid score (DIAAS). Since most edible legumes are mainly available in their processed forms, an interrogation of these processing methods, which could be traditional (e.g., cooking, milling, extrusion, germination, and fermentation) or based on emerging technologies (e.g., high-pressure processing (HPP), ultrasound, irradiation, pulsed electric field (PEF), and microwave), is not only critical but also necessary given the capacity of processing methods to influence protein digestibility. Therefore, this timely and important review discusses how each of these processing methods affects legume seed digestibility, examines the potential for improvements, highlights the challenges posed by antinutritional factors, and suggests areas of focus for future research.

Identification and Effects of Skim Milk-Derived Bioactive Antihypertensive Peptides

Bioactive peptides are generated during milk fermentation or enzymatic hydrolysis. Lactobacillus (L) helveticus is commonly used to produce some types of fermented milk products. Fermented milk derived bioactive peptides are known to be beneficial in human health. Anti-hypertensive peptides play a dual role in the regulation of hypertension through the production of the vasoconstrictor angiotensin II and its inactivation of the vasodilator bradykinin. MALDI MS/MS, nano-LC/MS/MS and RP-HPLC were used to isolate peptides showing angiotensin converting enzyme inhibition (ACE-I) from 12% fermented skim milk using a combination of L. helveticus and Flavourzyme®. The fermentation procedure facilitated the identification of 133 anti-hypertensive peptides and 75% short chain amino acids, and the three with the highest ACE-I activity reduced blood pressure in a rat model of hypertension. The freeze- dried extract was supplemented in rodent chow. In this study 14-week-old male spontaneously hypertensive rats were fed for 10 weeks with the identified peptides added to chow and compared to controls supplemented with skim milk powder. Blood pressure (BP) decreased significantly (p < 0.05) from 6 to 10 weeks of FS groups (120/65 mmHg) compared with the NFS control groups, where the BP increased significantly (220/150 mmHg) (p < 0.05). The F6 fraction provided bioactive peptides with stronger antihypertensive properties than other fractions. Skim milk fermented by L. helveticus and Flavourzyme® generates several bioactive peptides which have a blood pressure lowering effect in hypertensive disease.

Pea cell wall integrity controls the starch and protein digestion properties in the INFOGEST in vitro simulation

The cell wall microstructure has been recognized to modulate the digestibility and bioaccessibility of nutrients in whole pulse foods, while the role of cell wall integrity is unclarified in the hydrolysis of intracellular nutrients during human gastrointestinal transit. Intact pea cells were isolated to prepare a series of cell wall integrity subjected to cooking and followed by the in vitro hydrolysis of starch and protein properties using the INFOGEST 2.0 in vitro simulation. Thermal properties showed that cell samples either in raw or cooked form with different wall integrity exhibited similar and higher starch gelatinization temperatures compared to the isolated starch counterpart. It was found that intact pea cells showed the limited hydrolysis extent of the maltose (16.2%) and NH2 (6.7%) compared to the damaged cells. In addition, intact cells also withheld the cell wall integrity throughout gastrointestinal digestion with minor rupture, and presented the higher protein molecular weight (70 kDa) in the SDS-PAGE profiles. Results suggested that the in vitro starch and protein digestion properties are modulated by the cell wall integrity, which may lead to lower glycemic response and open up the possibilities of designing health food products.

Genetic relationship study of some Vicia species by FISH and total seed storage protein patterns

BACKGROUND

Genus Vicia is a member of family Fabaceae and comprises 180 to 210 species. The most important species is faba bean (Vicia faba) which is still one of the most favourable grain legumes over all the world. The genus contains some additional food crops and a number of forage plants and some other weedy strains such as Vicia angustifolia and Vicia cordata. The aim of the present investigation is to elucidate the phylogenetic relationships among four Vicia species, two species (Vicia angustifolia L. ssp. Angustifolia (2n = 12) and Vicia cordata wulfen ex Hoppe (2n = 10)) belong to section Vicia, Vicia dalmatica A. Kern (2n = 12, section Cracca), and Vicia johannis tamamsch (2n = 14, section Faba).

RESULTS

Two tools have been applied to identify the genetic relationships among the examined species, double fluorescence in situ hybridization (FISH) has been used to localize the sites of 5S and 45S rDNA, and sodium dodecyl sulfate-poly acrylamide gel electrophoretic (SDS-PAGE) patterns of total seed storage protein fractions. Double FISH experiment has not shown any variation in the loci number, but the positions along the chromosomes were different; both Vicia johannis and Vicia dalmatica exhibited the same interstitial 45S rRNA gene loci, while Vicia angustifolia and Vicia cordata have shown single large stretched 45S rRNA loci almost at the terminal region of the shortest chromosome. It could be concluded from the similarity matrix among the Vicia species as computed according to Jaccard coefficient from the SDS-PAGE, that V. cordata is similar to V. angustifolia and V. dalmatica by a percentage of 73 and 69%, respectively, and the most related species to V. johannis is V. dalmatica (~ 64%).

CONCLUSION

FISH and SDS-PAGE of the total seed storage proteins together reflected the similar genetic relationship among the studied species as fellows, V. angustifolia is more related to V. cordata then comes V. dalmatica and then V. johannis which is at a distal position from the other species.

Effect of genotype on the physicochemical and functional attributes of faba bean (Vicia faba L.) protein isolates

The functionality and surface characteristics of protein isolates prepared from seven genotypes of faba bean were investigated. All factors studied were independent of genotype. The average protein and isolate (~94% protein) yields were ~77% and ~25%, respectively, using an alkaline extraction process followed by isoelectric precipitation. The overall averages were: surface charge +22.1 mV, surface hydrophobicity 47.2 arbitrary units, and surface and interfacial tensions of 65.0 mN/m and 10.7 mN/m, respectively. The ratio of the major globulin fractions (legumin:vicilin) shifted from 3.8 for the flours to 4.5 in the isolates. Average values for foaming capacity and stability, emulsion capacity, creaming stability, oil holding capacity, emulsifying activity and stability indices, and solubility were 162.0%, 65.0%, 184.0 g/g, 94.0%, 5.7 g/g, 13.0 m²/g, 10.7 min, and 81.0%, respectively. The lack of significant varietal effects would be advantageous to food processors as the source of the feedstock would not affect ingredient functionality.

Lab-on-a-chip and SDS-PAGE analysis of hemolymph protein profile from Rhipicephalus microplus (Acari: Ixodidae) infected with entomopathogenic nematode and fungus

In the present study, lab-on-a-chip electrophoresis (LoaC) was suggested as an alternative method to the conventional polyacrylamide gel electrophoresis under denaturing conditions (SDS-PAGE) to analyze raw cell-free tick hemolymph. Rhipicephalus microplus females were exposed to the entomopathogenic fungus Metarhizium anisopliae senso latu IBCB 116 strain and/or to the entomopathogenic nematode Heterorhabditis indica LPP1 strain. Hemolymph from not exposed or exposed ticks was collected 16 and 24 h after exposure and analyze by SDS-PAGE or LoaC. SDS-PAGE yielded 15 bands and LoaC electrophoresis 17 bands. Despite the differences in the number of bands, when the hemolymph protein profiles of exposed or unexposed ticks were compared in the same method, no suppressing or additional bands were detected among the treatments regardless the method (i.e., SDS-PAGE or chip electrophoresis using the Protein 230 Kit®). The potential of LoaC electrophoresis to detect protein bands from tick hemolymph was considered more efficient in comparison to the detection obtained using the traditional SDS-PAGE method, especially when it comes to protein subunits heavier than 100 KDa. LoaC electrophoresis provided a very good reproducibility, and is much faster than the conventional SDS-PAGE method, which requires several hours for one analysis. Despite both methods can be used to analyze tick hemolymph composition, LoaC was considered more suitable for cell-free hemolymph protein separation and detection. LoaC hemolymph band percent data reported changes in key proteins (i.e., HeLp and vitellogenin) exceptionally important for tick embryogenesis. This study reported, for the first time, tick hemolymph protein profile using LoaC.

Nutritive quality and protein production from grain legumes in a boreal climate

BACKGROUND

Boreal cropping systems are heavily focused on the production of small-grain cereals; to improve their resilience to climate change and to achieve food and feed security, diversification is needed. This study investigated the potential of faba bean, narrow-leafed lupin and lentil as protein crops in southern Finland, where faba bean is traditional but the other two are novel.

RESULTS

Early cultivars of narrow-leafed lupin and lentil matured adequately. Protein concentration in faba bean was, at 32%, higher than the world average of 29%, while those of narrow-leafed lupin and lentil were close to their world averages. Protein yields decreased in the order faba bean > narrow-leafed lupin > lentil. Lipid content of faba bean and lentil was about 1.2% and that of narrow-leafed lupin about 5.5%, and fatty acid composition was largely oleic and linoleic in all three species.

CONCLUSION

Both lentil and narrow-leafed lupin can be added to the range of feed and food crops produced at high latitudes in Europe. While faba bean produces the greatest protein yield and lysine concentration, the higher sulfur amino acid concentration in lupin, its oil content and its adaptation to acid, sandy soils not suitable for faba bean make it an attractive alternative.