Alkaline Solubilization Research Articles

Multi-objective development of novel egg free cakes using quinoa protein and its quality attributes

This study explores the potential of utilizing quinoa protein as an egg substitute in bakery products for customers with health, culture/religion, or dietary restrictions. Quinoa protein was prepared from quinoa seed by alkaline solubilization followed by isoelectric precipitation and drying. Four different formulations of egg-free cakes were prepared by incorporating quinoa protein in egg equivalents of 50 g (Formulation 1), 75 g (Formulation 2), 100 g (Formulation 3), and 150 g (Formulation 4). The research involved Fourier-transform infrared spectroscopy and revealed such functional properties as proximate composition, physical properties, color, texture, microstructure, and sensory characteristics for the batters and the cakes. The incorporation of different quinoa protein concentrations significantly (p < 0.05) affected all the functional properties of the batters and the cakes. Such variables as crude protein and ash increased while moisture and fat contents decreased. The baking loss went down as the share of quinoa protein went up. The structural analysis showed an increase in gumminess and chewiness accompanied by a decrease in cohesiveness and elasticity. The analysis also revealed hardness and non-uniform changes. The lightness (L*) and yellowness (b*) of the cake surface and crumb decreased while the redness (a*) increased. The cakes prepared according to Formulation 4 with the greatest share of quinoa protein had a high nutritional value with reasonable concentrations of essential amino acids in general and a high level of lysine in particular. The same sample also received the highest score for overall sensory properties. The sensory assessment proved that quinoa protein could meet consumer expectations of egg-free cakes.

Buffalo worm (Alphitobius diaperinus) proteins: Structural properties, proteomics and nutritional benefits

Biophysical methods such as circular dichroism (CD) and differential scanning calorimetry (DSC) have been minimally used to characterize insect-derived proteins. This study examines the insect Alphitobius diaperinus as a potential protein source. Techniques such as alkaline solubilization coupled with isoelectric precipitation and Osborne fractionation were used to obtain protein concentrates and fractions (albumins, globulins, prolamins, glutelins). SDS-PAGE results showed dominant protein bands at 78.3, 73.3, 49.3, 34.5, 32.0, and 10.3 kDa. All fractions had over 60 % α-helix and β-sheet structures, indicating stable conformations. Prolamins showed high surface hydrophobicity and thermal stability. Nutritionally, glutelins exhibited the highest concentration of essential amino acids (68.75 g/100 g protein), and demonstrated superior In vitro protein-digestibility (84.04 %) as well as the highest In vitro protein-digestibility corrected amino acid score (73.11 %). Therefore, this study characterized the structural-function relationship of A. diaperinus proteins and collectively assessed their suitability and safety for human consumption.

Unraveling the fate of mycotoxins during the production of legume protein and other derived products

Consumers are increasingly looking for healthier and sustainable diets. Plant-based diets rich in legumes satisfy this demand. Legumes contain protein, dietary fibers and starch. Technological processes can separate these fractions, which can be used as supplements, or as ingredients. Nonetheless, legumes are susceptible to fungal infection, causing a potential health concern, since some fungi can produce mycotoxins: toxic secondary metabolites. The aim of this work was to analyze the fate of mycotoxins during different stages of the production process of legume derived products from the raw materials to final products. An extraction followed by liquid chromatography-tandem mass spectrometry was used for the analysis, revealing the presence of enniatin B (ENN B), alternariol monomethyl ether (AME), deoxynivalenol, T2-toxin, nivalenol, fumonisin B1 and sterigmatocystin in raw materials, intermediate products and side streams. The alkaline solubilization steps, were effective in reducing ENN B; however, AME was found in one of the final products.

Mechanistic insights into the foaming properties of potato proteins based on protein composition, colloidal state, and air-water interfacial properties

Potato proteins have been shown to be suitable alternatives for animal proteins in food foam formulations but their ability to form and stabilize foam is mechanistically ill-understood. The present study aimed to better understand the foaming properties of a protein fraction isolated from potato trimmings, a by-product from the potato industry. This was achieved by comparing the properties of these in-house isolated proteins to those of commercial and highly purified potato proteins. Protein isolates (53.8 ± 4.7 g/100 g dry weight) were produced from trimmings by alkaline solubilization (pH 9.0) and isoelectric precipitation (pH 4.0). The foaming properties of the in-house isolate at pH 3.0 and 7.0 were better than those of a blend of commercial potato proteins with similar relative amounts of patatin and protease inhibitors as the in-house isolate. Notably, this was the case despite the fact that more proteins were insoluble in the in-house isolate than in the commercial potato protein suspensions. Patatin and protease inhibitors were further shown to both contribute considerably to the formation and stabilization of foams. Interestingly, a beneficial effect on foam stability was found when patatin and protease inhibitors of various colloidal sizes were present. Additionally, impurities in the in-house isolates likely contributed to their superior foaming properties. In conclusion, a protein-rich fraction with good foaming properties can be recovered from potato trimmings. Mechanistic insights were gained into the foaming properties of potato protein (mixtures). This research also highlighted the importance of assessing protein colloidal state when investigating plant protein structure-function relationships.

Yeast Proteins: Proteomics, Extraction, Modification, Functional Characterization, and Structure: A Review.

Proteins are essential for human tissues and organs, and they require adequate intake for normal physiological functions. With a growing global population, protein demand rises annually. Traditional animal and plant protein sources rely heavily on land and water, making it difficult to meet the increasing demand. The high protein content of yeast and the complete range of amino acids in yeast proteins make it a high-quality source of supplemental protein. Screening of high-protein yeast strains using proteomics is essential to increase the value of yeast protein resources and to promote the yeast protein industry. However, current yeast extraction methods are mainly alkaline solubilization and acid precipitation; therefore, it is necessary to develop more efficient and environmentally friendly techniques. In addition, the functional properties of yeast proteins limit their application in the food industry. To improve these properties, methods must be selected to modify the secondary and tertiary structures of yeast proteins. This paper explores how proteomic analysis can be used to identify nutrient-rich yeast strains, compares the process of preparing yeast proteins, and investigates how modification methods affect the function and structure of yeast proteins. It provides a theoretical basis for solving the problem of inadequate protein intake in China and explores future prospects.

Optimization of fermentation temperature and time for production of an antifungal extract from Bacillus amyloliquefaciens B17

Background/Objective. Species of Bacillus are currently gaining interest because its ability to produce secondary metabolites with antifungal properties against various plant pathogenic fungi. The objective of this study was to optimize fermentation temperature and time for antifungal extract production by Bacillus amyloliquefaciens B17 and to verify its activity against plant pathogenic fungi Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea. Materials and Methods. A central composite design (CCD) with two factors and five levels (fermentation temperature: 23.7, 25, 28, 31, and 32.2 °C and fermentation time: 25, 46, 95, 144, and 164. 3 h) was used. Thirteen combinations of temperature and fermentation time were randomly performed. The thirteen crude extracts of B. amyloliquefaciens B17 were obtained from the cell-free fermentation broth by acid precipitation followed by alkaline solubilization. The response variable was the diameter of the inhibition halos generated by placing drops of the different crude extracts onto the medium already inoculated with a suspension of Gilbertella persicaria spores. Results. The optimal conditions for the production of the extract with the greatest antifungal activity in B. amyloliquefaciens B17 were 26.8 °C and 158.6 h. Conclusion. The optimized crude extract from B. amyloliquefaciens B17 exhibited a strong ability to inhibit mycelial growth and spore germination of Gilbertella persicaria, Choanephora cucurbitarum, Colletotrichum asianum, and Botrytis cinerea.

Characterization of industrial pea canning by-product and its protein concentrate obtained by optimized ultrasound-assisted extraction

This work aimed to optimize protein extraction from an industrial pea canning by-product by developing an ultrasound-assisted alkaline solubilization and isoelectric precipitation method. Proximate composition and microbial contamination (total bacterial count, total lactic acid bacteria, Enterobacteriaceae, yeasts and moulds) were assessed in the wet by-product. The protein concentrate obtained, the dry by-product and a commercial pea flour were analysed for protein content, water activity, colour and techno-functional properties. The optimal extraction conditions from the wet by-product were liquid-solid ratio 20 mL/g, pH 11, ultrasound amplitude 80 μm, time 2 × 30 min. The extraction from the dry by-product was not feasible. Sonication reduced extraction time from 4 h (magnetic stirring method) to 1 h and increased three-fold the extraction recovery (from 21.5% to 66.6%). The concentrate had a 74.8 g/100 g DM protein content. The SDS-PAGE revealed protein degradation in some specimens, probably because of fermentation and enzymatic hydrolysis before sampling. However, the microbial counts in the concentrate, mainly related to lactic acid bacteria, were always below the guideline values. Our results demonstrate that the pea canning by-product is a valuable raw material for protein recovery and that the proposed method allows rapid and direct treatment, avoiding drying costs and microbial proliferation.

Evaluation of the functional properties of a protein isolate from Arthrospira maxima and its application in a meat sausage

Arthrospira maxima is a microalga that has been collected in Lake Texcoco in the Valley of Mexico since pre-Hispanic times and has been a traditional food source due to its high biomass production and protein content (50–60 %), making it promising for protein extraction. In this context, a protein isolate was obtained from powdered biomass of Arthrospira maxima (PbAm) by alkaline solubilization (pH 11) and isoelectric precipitation (pH 4.2). Arthrospira maxima protein isolate (AmPI) presented higher protein content (82.58 %) and total amino acids compared to PbAm. Functional properties of AmPI were evaluated in comparison with PbAm and soy protein isolate (SPI). Protein extraction resulted in a significant increase in protein solubility (PS) and foaming capacity (FC) of up to 87.78 % and 238.10 %, respectively. Emulsifying capacity (EC) of AmPI was superior to that of PbAm and SPI in pH range 5–7. Inclusion of AmPI as a partial substitute for SPI in the formulation of meat sausages was evaluated by implementing four treatments: T1 (15 % AmPI, 85 % SPI), T2 (10 % AmPI, 90 % SPI), T3 (5 % AmPI, 95 % SPI) and T4 (0 % AmPI, 100 % SPI). Although the texture attributes remained unchanged, a significant reduction in color parameters was observed as the concentration of AmPI increased. An inclusion of 15 % AmPI significantly enhanced the nutritional quality of meat sausages. Results highlight the excellent properties of AmPI, confirming Arthrospira maxima as a promising protein source in the food industry.

Integrating bead milling and alkaline solubilization for enhanced protein recovery from microalgae: A comprehensive approach

Microalgae, Chlorella vulgaris exhibits substantial potential as a sustainable food ingredient, but its robust cell wall and limited protein solubility hinder industrial scale protein recovery. A comprehensive solution was devised, integrating dry bead milling and alkaline solubilization. In this method, cells were initially disrupted with bead milling followed by alkali (NaOH) treatment. Without bead milling, protein extraction yield was very low (5.0 % with water, 16.8 % with 0.1 M NaOH) at a biomass loading of 20 g/L. However, the integrated approach significantly improved these results, achieving a maximum protein extraction yield of about 47.3 % at a biomass loading of 100 g/L. The optimized conditions for both dry bead milling (frequency 26 Hz, duration 1.0 h) and alkaline solubilization (biomass weight to NaOH molar ratio 200–250 (g/M), 37 °C, mixing time 1.0 h) played a pivotal role in realizing these improved results. This integrated approach effectively addresses the challenges and holds industrial relevance, offering a more efficient way to extract microalgal protein.

Characteristics of mildly refined soy protein fractions for cleaner soy‐food development

SummaryIn recent years, the markets for plant‐based products and plant protein have experienced a remarkable global expansion. The demand for plant‐based products, ranging from meat substitutes and dairy alternatives to plant‐based snacks and beverages, has surged exponentially. Soy protein, among all the plant protein resources, held a significant market share in the plant‐based industry, reflecting its popularity and widespread use. The selection of an appropriate soy fractionation process is essential for the development of cleaner and more sustainable soy‐based food products. This study compared three different soy protein fractions (SPFs) obtained through mild fractionation processes, each with unique chemical compositions and functionalities. Aqueous ethanol washing process resulted in the fractions with the highest protein purity and water holding capacity, while the simplified aqueous extraction method coupled with either an alkaline solubilisation step (SAE‐Alkaline) or an acid precipitation step (SAE‐Acid) yielded protein fractions with superior solubility, thermal stability, and gel strength. The choice of fractionation route has significant implications for the production of protein‐rich ingredients, and prioritising sustainable processing methods can contribute to the development of innovative and environmentally friendly soy‐based foods.

Beneficiation of rare earth elements contained in phosphogypsum using sequenced treatment process

Concerns regarding the availability of rare earth elements (REEs) and the depletion of natural resource reserves have made it necessary to look for a significant breakthrough that may pave the way for the mining of several low-grade deposits and secondary resources. Phosphogypsum (PG) is one of the promising alternatives to preserve a steady flow of REEs and mitigate the loss of natural reserves. Nonetheless, the low concentration of REEs in PG implies the necessity of an enrichment step prior to any extraction attempt. To tackle the difficult challenges of REEs concentration from diluted phosphate-derived by-products, this study concentrated on determining the likely speciation of REEs and their beneficiation, as well as conducting an economic assessment of the potential industrial value of REEs present in PG. It was found that the alkaline solubilization of the gypsum phase of PG using Na4EDTA favored the beneficiation of different qualities of PG. Moreover, it was found that the abatement of residual undesirable phases by mineral acid (HF) for quartz (SiO2) elimination, or pyrometallurgical process, improved the enrichment of REEs in the residual concentrate. A REEs concentration of 4390.23 ppm and 4317.55 ppm were achieved after sequenced alkaline, neutral, and acidic treatment of low-grade PG (238.22 ppm); and sequenced alkaline, neutral, and pyrometallurgical treatment of high-grade PG (389.75 ppm), respectively. Furthermore, an elementary assessment of REEs speciation revealed that REEs could potentially be present as insoluble rare earth fluorides (REF3) and/or rare earth phosphates (REPO4).

Alkaline solubilization of microalgal protein and its impact on the functional properties of protein extract

Microalgal alternative proteins are increasingly recognized as a sustainable and promising source for future food production. Despite the widespread use of alkaline solubilization in protein extraction, its influence on the functional properties of microalgal protein extracts has received limited attention. This study marks the pioneering effort to assess the impact of alkaline (NaOH) solubilization on both the extraction process and the functional properties of Chlorella vulgaris protein extract (CVPE) obtained through isoelectric precipitation. With the gradual escalation of alkaline concentration from 0 to 0.7 M, there was a notable improvement in protein extraction efficiency, increasing significantly from 6.22 % to 56.23 %. However, elevated NaOH concentrations resulted in protein degradation, as evidenced in SDS-PAGE studies. Alkaline solubilization exhibited a positive impact on various functional properties of CVPE. It enhanced solubility, water absorption capacity, foaming capacity and stability, as well as emulsifying activity and stability. However, there was a slight decrease in oil absorption capacity with increasing NaOH concentration. Notably, the maximum solubility, oil adsorption capacity, foaming capacity, and emulsion activity of CVPE were 2.3-, 1.8-, 2-, and 1.3-fold higher, respectively, than those of commercial soy protein isolate (SPI). This highlights the effectiveness of alkaline solubilization in modifying C. vulgaris protein and emphasizes the high potential of CVPE as a functional food ingredient.

Renewing the potential of rice crop residues as value-added products in the cosmetics industry

Purpose of this study is to explore the extraction of potentially valuable cosmetic ingredients from rice crop residues, aiming to mitigate their environmental impact. MethodsWe employed AOAC methods to analyze the fat, protein, ash, fiber, soluble, and insoluble carbohydrate content in these residues. To identify sugars rich in galactose and acidic sugars, a total soluble carbohydrate extraction was performed. Cellulose, as part of the insoluble carbohydrates, was isolated through alkaline and acid hydrolysis, while sodium silicate was derived from the ash. Characterization of insoluble cellulose and silicate involved techniques like FTIR, DSC, PXRD, microphotography, porosity assessments, and water absorption studies. For proteins, alkaline solubilization and precipitation at the isoelectric point were utilized, with quantification via BCA and amino acid profiling through gas chromatography. Evaluation of radical scavenging capacity using DPPH led to the calculation of apparent molecular weight via SDS-PAGE. ResultsThe results revealed low levels of gum, mucilage, and pectin in both residues, contrasting with a high concentration of insoluble polysaccharides. Among these, Iβ cellulose displayed potential attributes for cosmetic applications due to its oil and water adsorption characteristics. However, silicates obtained from the ashes did not exhibit direct use potential. In terms of protein extraction, we observed antioxidant properties, with enhanced performance through enzymatic hydrolysis, achieving a hydrolysis degree of 30.41% and a DPPH radical absorption rate exceeding 70%. ConclusionRice residues, particularly husk and straw, shown valuable substances suitable for potential cosmetic applications, encompassing cellulose, hydrolyzed proteins, and ash as a silicate precursor.

Enhancing the Gelation Behavior of Transglutaminase-Induced Soy Protein Isolate(SPI) through Ultrasound-Assisted Extraction.

Gelation, as an important functional property of soy protein isolate (SPI), can be improved by some green technologies in food manufacturing, including ultrasound, ultrahigh pressure and microwave treatments. This work investigated the effect of an alkaline solubilisation step in SPI extraction combined with sonication on protein properties. The TGase-induced gel of the modified SPI was prepared to explore the effect of ultrasound on gel properties, including structures, strength, water-holding capacity and rheological properties. Additionally, the differences between traditional ultrasound modification of SPI and current modification methods were analyzed. The results showed that the ultrasonication-assisted extraction method could result in a significant increase in extraction rate from 24.68% to 42.25%. Moreover, ultrasound-assisted modification of SPI gels induced with transglutaminase (TGase) exhibited significant improvement in mechanical properties, such as texture, water-holding capacity and rheological properties, In particular, SPI extracted at 400 W ultrasound intensity for 180 s showed the best overall performance in terms of gel properties. Our method efficiently uniformizes gel structure, enhancing mechanical properties compared to conventional ultrasound methods, which reduced energy consumption and costs. These findings provide insights into the production of high-gelation SPI in food manufacturing.

Investigation of functional, antioxidant, anti-inflammatory, and antidiabetic properties of legume seed protein hydrolysates

Plant-derived hydrolysates are emerging as promising agents in the management of diverse ailments due to their ensuing functional and bioactive properties. This study investigated the functional, antioxidant, anti-inflammatory, and antidiabetic properties of hydrolysates from Erythrina senegalensis and Vigna subtenarrea seeds. Crude proteins were isolated via alkaline solubilization, followed by acid precipitation to the isoelectric point. Respective protein isolates were hydrolyzed using trypsin and pepsin at an enzyme-substrate ratio of 1:8 (v/v) for 1–9 h. Pepsin hydrolysates after 9 h elicited the highest solubilities of 95.54 % and 94.24 % at pH 13, while, pepsin and trypsin hydrolysates of E. senegalensis digested for 1 and 9 h displayed the highest 1,1-diphenyl-2-picrylhydrazyl radical-scavenging (10-IC50 = 2.959 mg/mL) and total antioxidant capacity (7.243 mgAAE/g), respectively. Correspondingly, pepsin and trypsin hydrolysates of E. senegalensis hydrolyzed for 5 h demonstrated the most potent anti-inflammatory activities by cogently inhibiting xanthine oxidase and lipoxygenase activities with IC50 of 0.161 ± 0.111 and 0.018 ± 0.011 mg/mL, respectively. Trypsin hydrolysates of V. subterranea hydrolyzed for 5 h potently inhibited the activities of α-amylase and α-glucosidase with respective IC50 of 0.297 ± 0.060 and 0.314 ± 0.064 mg/mL. Overall, pepsin and trypsin hydrolysates of E. senegalensis demonstrated pronounced functional bioactivities relative to V. subterranea hydrolysates. This study concludes that both seeds could serve as unique matrices of potential functional bioactive peptides with prospects for managing diabetes.

Valorization of pulp and viscera from hybrid sorubim and pacu by production of protein concentrate using alkaline solubilization

Fish protein concentration (FPC) by alkaline solubilization has proven to be an alternative method in adding value to muscle-based materials. The aim of this work was to evaluate the influence of different processes (decanting/sieving or centrifugation), reagents (sodium bicarbonate or sodium hydroxide) and washing cycles (1–4) on the quality of protein concentrates obtained from mechanically separated meat (MSM) and viscera of hybrid sorubim (Pseudoplatystoma reticulatum × P. corruscans) and pacu (Piaractus mesopotamicus) fishes. The protein concentrate was obtained by washing the viscera or MSM during up to four cycles (4:1 solution:meat ratio). In each cycle, the liquid waste and fat were removed by decanting/sieving or centrifugation. Moisture, crude protein, crude fat and crude ash contents were determined after each washing cycle. The moisture and protein contents increased immediately after the first washing up to 77.88% (dry basis). The lipid content decreased with the cycles down to 2.99% (dry basis). Higher FPC yield was obtained for MSM during the centrifugation process compared to the decantation/sieving process. Two weight yields above 100% were found in procedures with NaHCO3 and MSM of hybrid sorubim and pacu, probably due to the larger capacity of gel formation during protein concentration. Differences related to the fish species were more evident than the processes and utilized reagents.

The Effect of Multistage Refinement on the Bio-Physico-Chemical Properties and Gel-Forming Ability of Fish Protein Isolates from Mackerel (Rastrelliger kanagurta).

The objective of this research was to improve the protein extraction processes of Rastrelliger kanagurta (Indian mackerel) to generate protein isolate with enhanced bio-physico-chemical properties and gel-forming ability. To achieve this, two novel approaches were designed that utilized an additional alkaline separation step and were compared to a conventional process: acid solubilization → alkaline solubilization → pI and acid solubilization → pI → alkaline solubilization. The novel extraction designs resulted in a lower lipid content, lipid oxidation, and TCA-soluble peptides, as well as improving the color and sensory features of the refined proteins, which corresponded to the lowest total heme pigments (p < 0.05). Furthermore, the protein isolate recovered with the modified processes showed significant changes in biochemical properties (decreases in Ca2+-ATPase activity/reactive sulfhydryl content and an increase in surface hydrophobicity) and dynamic rheological behavior. As a result, by altering the extraction procedure it was possible to obtain improved gel characteristics such as gel strength, color, expelled moisture, and improved gel microstructure. Moreover, this study demonstrated that the gel network was partly stabilized by disulfide bonds, according to SDS-PAGE. Overall, this study demonstrates that by optimizing protein extraction procedures a considerable improvement in quality can be achieved and that an additional alkaline extraction after isoelectric point precipitation results in the optimized gel-forming ability of mackerel proteins.

Polypeptide composition of major oilseed proteins and functional properties of extracted protein products: A concise review

AbstractOilseeds are grown mainly for their oil content but the residues (meals) that remain after defatting are excellent sources of plant protein ingredients. However, to serve as useful ingredients, the extracted proteins must meet industry expectations in terms of functional performance. Protein functionality is influenced by structural conformation, amino acid composition, type of polypeptides, presence of non‐protein materials (carbohydrates, lipids, and polyphenols), which in turn can be modified by the extraction method. Defatted oilseed meals are extracted mostly through the pH shift method, which involves alkaline solubilization followed by acid‐induced protein precipitation at the isoelectric point. A less popular method is called the protein micellar mass whereby the oilseed meal proteins are extracted with a NaCl solution, which is later diluted to reduce the ionic strength to a level where the proteins are no longer soluble and hence precipitate. A third method utilizes carbohydrases and phytases to first digest non‐protein materials from the oilseed meal into smaller units that are then removed by membrane ultrafiltration to leave behind a protein‐rich extract. These methods produce mainly two types of isolated oilseed proteins, concentrates (60%–89% protein content) and isolates (≥90% protein content), which can differ in terms of their protein conformation, solubility, and functionality as food ingredients. Therefore, this review provides an overview of the extraction and isolation as well as structural and functional properties of soybean, peanut, canola, hemp seed, sunflower, and sesame seed proteins.

Bioactivities of Garcinia kola enzymatic hydrolysates at different enzyme–substrate ratios

Natural products, such as enzymatic hydrolysates and bioactive peptides from dietary sources, are safe alternatives to synthetic compounds linked to various deleterious effects. The purpose of this study is to determine the in vitro bioactivities (antioxidant and anti-inflammatory activities) of Garcinia kola seeds enzymatic hydrolysates (GKPHs) at different enzyme (pepsin)-substrate ratios. G. kola protein, isolated by alkaline solubilization and acid precipitation, was hydrolyzed with pepsin at varying enzyme–substrate (E:S) ratios. The antioxidant parameters investigated include 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical scavenging, hydrogen peroxide scavenging and ferrous ion (Fe2+) chelating activities. For anti-inflammatory properties, membrane stabilization and protein denaturation activities tests were used. GKPH produced at 1:32 had the highest degree of hydrolysis (66.27 ± 4.21%). All GKPHs had excellent in vitro anti-inflammatory properties. However, only enzymatic hydrolysates produced at 1:16 (E:S) ratio chelated iron (II) and as well had the highest percentage hemolysis inhibition of 84.45 ± 0.007%, percentage protein denaturation inhibition of 53.36 ± 0.01% at maximum concentration and exhibited highest DPPH scavenging activity (87.24 ± 0.10%). The enzymatic hydrolysates had excellent solubility, emulsifying and foaming properties. It could be deduced from this study that pepsin at a ratio of 1:16 of G. kola protein produced the most effective enzymatic hydrolysates in terms of their antioxidant and anti-inflammatory activities. G. kola pepsin enzymatic hydrolysates, thus, have potential in development as functional foods and as therapeutics pharmaceutical industries in the management of diseases associated with oxidative stress and inflammation owing to their excellent functional, antioxidant and anti-inflammatory properties.

Structural Properties of Quinoa Protein Isolate: Impact of Neutral to High Alkaline Extraction pH.

In this work, we extracted proteins from white quinoa cultivated in the northeast of Qinghai-Tibet plateau using the method of alkaline solubilization and acid precipitation, aiming to decipher how extraction pH (7-11) influenced extractability, purity and recovery rate, composition, multi-length scale structure, and gelling properties of quinoa protein isolate (QPI). The results showed that protein extractability increased from 39 to 58% with the increment of pH from 7 to 11 whereas protein purity decreased from 89 to 82%. At pH 7-11, extraction suspensions and QPI showed the similar major bands in SDS-PAGE with more minor ones (e.g., protein fractions at > 55 or 25-37 kDa) in suspensions. Extraction pH had limited effect on the secondary structure of QPI. In contrast, the higher-order structures of QPI were significantly affected, e.g., (1) emission maximum wavelength of intrinsic fluorescence increased with extraction pH; (2) surface hydrophobicity and the absolute value of zeta-potential increased with increasing extraction pH from 7 to 9, and then markedly decreased; (3) the particle size decreased to the lowest value at pH 9 and then increased to the highest value at pH 11; and (4) denaturation temperature of QPI had a large decrease with increasing extraction pH from 7/8 to 9/10. Besides, heat-set QPI gels were formed by loosely-connected protein aggregates, which were strengthened with increasing extraction pH. This study would provide fundamental data for industrial production of quinoa protein with desired quality.