Functional properties of protein isolates from Caragana korshinskii Kom. extracted by three different methods

Leveraging Bioprocessing Strategies to Achieve the Simultaneous Extraction of Full-Fat Chickpea Flour Macronutrients and Enhance Protein and Carbohydrate Functionality

The concurrent extraction of lipids, proteins, and carbohydrates can be achieved by aqueous and enzymatic extraction processes, circumventing the low extractability by mechanical pressing and the use of flammable solvents. The use of alkaline protease, preceded or not by carbohydrase pretreatments, was evaluated on the extractability of oil, protein, and carbohydrates from full-fat chickpea flour and protein functionality. Enzymatic extraction increased oil and protein extractability from 49.8 to 72.0–77.1% and 62.8 to 83.5–86.1%, respectively. Although the carbohydrase pretreatments before the addition of protease did not increase oil and protein extractability, the carbohydrate content of the extracts increased from 7.68 to 9.17−9.33 mg/mL, accompanied by the release of new oligosaccharides in the extracts, as revealed by LC–MS/MS characterization. Enzymatic extraction yielded proteins with significantly higher solubility (25.6 vs. 68.2–73.6%) and digestibility (83.8 vs. 90.79–94.67%). Treatment of the extracts with α-galactosidase completely removed the flatulence-causing oligosaccharides (stachyose and raffinose). This study highlights the effectiveness of environmentally friendly bioprocessing strategies to maximize lipid, protein, and oligosaccharide extractability from full-fat chickpea flour with concurrent improvements in protein solubility and in vitro digestibility, reduction of flatulence related oligosaccharides, and generation of a more diverse pool of oligosaccharides for subsequent prebiotic evaluation.

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Structural evaluation of cytochrome c by Raman spectroscopy and its relationship with apoptosis and protein degradation in postmortem bovine muscle

Structural changes of cytochrome c and its relationship with apoptosis and protein degradation of bovine muscle during postmortem aging were investigated. Results from amide I and amide II ~ VI showed that the π* orbital d electron decreased, the π electron density increased, and the frequency of the C-N stretching vibration increased. The distance between heme Fe and N atoms of the porphyrin decreased, the bond length decreased, and the heme core size decreased. Besides, Fe ligand vibration related Raman bands of cytochrome c had red (right) shift gradually with the extension of aging. The apoptotic rate and the degradation products of desmin and troponin-T were increased (P < 0.05). Correlation analysis results suggested that Fe ligand vibration, not amide I ~ VI related Raman bands were correlated with cytochrome c mediated apoptosis and degradation of myofibrillar protein of bovine muscle during aging.

Structural, physicochemical and functional properties of Semen Ziziphi Spinosae protein

Semen Ziziphi Spinosae (Ziziphus jujuba Mill. var. spinosa (Bunge) Hu ex H. F. Chou) is a functional food and a traditional Chinese medicine (TCM) in China. Herein, Semen Ziziphi Spinosae protein (SZSP) was prepared by an alkaline extraction and acid precipitation method, of which the structural, physicochemical, functional and emulsion properties were investigated. Results showed that SZSP contained an ideal amino acid composition. The structural properties of the proteins were characterized using Fourier transform infrared spectroscopy (FTIR), relative fluorescence and circular dichroism (CD) spectroscopy analysis. The electrophoresis profiles showed that the main molecular weight of the protein components was about 10-40 kDa and contained some glycoproteins. Differential scanning calorimetry analysis indicated that the denaturation temperature of SZSP was 110.5 °C. The functional properties showed that SZSP has good water and oil absorption capacity, high emulsifying ability and foaming stability. The overall results suggest that SZSP is a promising protein source for the functional food industry.

Biological properties of almond proteins produced by aqueous and enzyme-assisted aqueous extraction processes from almond cake

The almond cake is a protein-rich residue generated by the mechanical expression of the almond oil. The effects of the aqueous (AEP) and enzyme-assisted aqueous extraction processes (EAEP) on the biological properties of the almond cake protein were evaluated. Total phenolic content (TPC), antioxidant capacity, inhibitory effects against crucial enzymes related to metabolic syndrome, antimicrobial potential, and in vitro protein digestibility profile were assessed. EAEP provided the best results for antioxidant capacity by both ORAC (397.2 µmol TE per g) and ABTS (650.5 µmol TE per g) methods and also showed a high (~ 98%) potential for α-glucosidase inhibition. The AEP resulted in protein extracts with the highest lipase inhibition (~ 70%) in a dose-dependent way. Enzymatic kinetic analyses revealed that EAEP generated uncompetitive inhibitors against α-glucosidase, while EAEP, AEP, and HEX-AEP (used as control) generated the same kind of inhibitors against lipase. No protein extract was effective against any of the bacteria strains tested at antimicrobial assays. An in silico theoretical hydrolysis of amandin subunits corroborated with the results found for antioxidant capacity, enzyme inhibitory experiments, and antimicrobial activity. Digestibility results indicated that the digestive proteases used were efficient in hydrolyzing almond proteins, regardless of the extraction applied and that HEX-AEP presented the highest digestibility (85%). In summary, EAEP and AEP skim proteins have the potential to be used as a nutraceutical ingredient. The biological properties observed in these extracts could help mitigate the development of metabolic syndrome where EAEP and AEP skim proteins could be potentially used as a prophylactic therapy for diabetes and obesity, respectively.

Effect of maleylation on physicochemical and functional properties of rapeseed protein isolate

Influence of maleylation on the physicochemical and functional properties of rapeseed protein isolate was studied. Acylation increased whiteness value and dissociation of proteins, but reduced free sulfhydryl and disulfide content (p < 0.05). Intrinsic fluorescence emission and FTIR spectra revealed distinct perturbations in maleylated proteins' tertiary and secondary conformations. Increase in surface hydrophobicity, foaming capacity, emulsion stability, protein surface load at oil-water interface and decrease in surface tension at air-water interface, occurred till moderate level of modification. While maleylation impaired foam stability, protein solubility and emulsion capacity were markedly ameliorated (p < 0.05), which are concomitant with decreased droplet size distribution (d 32). In-vitro digestibility and cytotoxicity tests suggested no severe ill-effects of modified proteins, especially up to low degrees of maleylation. The study shows good potential for maleylated rapeseed proteins as functional food ingredient.

Characterization of heat-set gels from RuBisCO in comparison to those from other proteins

To anticipate a future shortage in functional proteins, it is important to study the functionality of new alternative protein sources. Native RuBisCO was extracted from spinach, and its gelation behavior was compared to other native proteins from animal and plant origins. Protein gels were analyzed for their mechanical gel properties during small and large deformation and for their microstructure. Heat-induced aggregation and network formation of RuBisCO resulted in gels with unique characteristics compared to, for example, whey protein and egg white protein. Having a very low critical gelling concentration and low denaturation temperature, RuBisCO readily forms a network with a very high gel strength (G', fracture stress), but upon deformation it has a brittle character (low critical strain, low fracture strain). This breakdown behavior can be explained by the dominant role of hydrophobic and hydrogen bonds between RuBisCO molecules during network formation and by the coarse microstructure. RuBisCO was shown to exhibit high potential as a functional ingredient giving opportunities for the design of new textures at low protein concentration.

Chemical Characterization and Nutritional Analysis of Protein Isolates from Caragana korshinskii Kom

Plant-based proteins are valuable supplements to compensate the gap between supply and demand in the food or feed industry. However, they lack essential amino acids, such as lysine in cereal grains and sulfur-containing amino acids in legumes, which greatly limit their wider uses for human and animals. In this study, the contents of nutritional ingredients and antinutritional factors of Caragana korshinskii Kom. and its protein isolates were quantitatively investigated. It was shown that the crude protein contents of C. korshinskii Kom. and its protein isolates obtained by alkaline extraction method (Al-CPI) and acetone precipitation method (A-CPI) were 9.1, 50.1, and 42.6%, respectively. Amino acid contents in C. korshinskii Kom., Al-CPI, and A-CPI basically exceeded the FAO/WHO (2007) reference pattern for adults except sulfur-containing amino acids. The lysine levels in C. korshinskii Kom., Al-CPI, and A-CPI were 4.1, 3.1, and 3.8 mg/100 mg crude protein respectively, which were higher than some other kinds of cereal grains. The methionine in A-CPI (1.39 mg/100 mg crude protein) was even higher than that in soybean. The antinutritional factors in C. korshinskii Kom. and Al-CPI were generally lower than those in some other kinds of legumes except total phenol and tannin. Total phenol and tannins in Al-CPI were 19.02 and 5.66 mg/g dry substance, respectively, but they were undetectable in A-CPI. This study provided a detailed analysis on nutritional and antinutritional factors in C. korshinskii Kom. and its protein isolates, indicating that they have a great potential on food and feed additives.