Isoelectric Precipitation Method Research Articles

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.

Extraction, structural and functional properties of lipophilic protein isolated from peanut defatted powder

Peanut isolated protein (PIP), peanut arachin (ARA), and peanut lipophilic protein (PLP) were obtained from peanut defatted powder (PDP) by the isoelectric point precipitation method. and their chemical, structural, and functional properties were evaluated. Chloroform-methanol method disclosed that PLP contained largest amount of lipids (10.98 ± 0.34%). Fourier transform infrared spectroscopy and X-ray diffraction detected that the four proteins had similar spectrum charateristics. However, PLP displayed the highest contents of α-helix and β-sheet indicating a more compact tertiary structure accompanied by significantly highest solubility, emulsifiability, and emulsion stability compared to other three protein components (P < 0.05). Both the water holding capacity and fat holding capacity of PLP were higher, but its gel forming capacity and gel stability were lower compared to ARA. Composition analysis demonstrated that PLP had similar amino acid pattern to that of PIP, and each 100g of PLP contained 7.24g unsaturated fatty acid which composed of 17 fatty acids. These results suggested that PLP was a lipid-rich protein in peanut which could be a potential functional ingredient in the food industry.

Modification of the physicochemical, functional, biochemical and structural properties of a soursop seed (Annona muricata L.) protein isolate treated with high-intensity ultrasound

The obtained seeds from fruit processing are considered by-products containing proteins that could be utilized as ingredients in food manufacturing. However, in the specific case of soursop seeds, their usage for the preparation of protein isolates is limited. In this investigation a protein isolate from soursop seeds (SSPI) was obtained by alkaline extraction and isoelectric precipitation methods. The SSPI was sonicated at 200, 400 and 600 W during 15 and 30 min and its effect on the physicochemical, functional, biochemical, and structural properties was evaluated. Ultrasound increased (p < 0.05) up to 5 % protein content, 261 % protein solubility, 60.7 % foaming capacity, 30.2 % foaming stability, 86 % emulsifying activity index, 4.1 % emulsifying stability index, 85.4 % in vitro protein digestibility, 423.4 % albumin content, 83 % total sulfhydryl content, 316 % free sulfhydryl content, 236 % α-helix, 46 % β-sheet, and 43 % β-turn of SSPI, in comparison with the control treatment without ultrasound. Furthermore, ultrasound decreased (p < 0.05) up to 50 % particle size, 37 % molecular flexibility, 68 % surface hydrophobicity, 41 % intrinsic florescence spectrum, and 60 % random coil content. Scanning electron microscopy analysis revealed smooth structures of the SSPI with molecular weights ranging from 12 kDa to 65 kDa. The increase of albumins content in the SSPI by ultrasound was highly correlated (r = 0.962; p < 0.01) with the protein solubility. Improving the physicochemical, functional, biochemical and structural properties of SSPI by ultrasound could contribute to its utilization as ingredient in food industry.

Drying Technique Providing Maximum Benefits on Hydrogelling Ability of Avocado Seed Protein: Spray Drying.

The current study focused on creating natural hydrogels consisting of mixtures of avocado seed proteins dried with different techniques and locust bean gum. Proteins were extracted from avocado seed by alkali and isoelectric precipitation methods. Avocado seed proteins were dried by five different drying methods, namely ambient drying, oven drying, vacuum drying, freeze drying, and spray drying. FT-IR spectra were used to analyze the chemical structure of proteins dried using various techniques. Additionally, hydrogel models were constructed in the presence of avocado seed proteins and locust bean gum to clarify the effect of drying techniques on their hydrogelling ability. The impact of drying techniques on the functional behavior of hydrogels was notable. The maximum water holding capacity values were detected in the hydrogel system containing spray-dried proteins (93.79%), followed by freeze-dried (86.83%), vacuum-dried (76.17%), oven-dried (72.29%), and ambient-dried (64.8%) counterparts. The swelling ratio was 34.10, 33.51, 23.05, 18.93, and 14.39% for gels in the presence of freeze-dried, spray-dried, vacuum-dried, oven-dried, and ambient-dried proteins, respectively. Additionally, the desirable values for the amount of protein leaking from the systems prepared using spray-dried (7.99%) and freeze-dried (12.14%) proteins were obtained compared to others (ambient-dried: 24.03%; oven-dried: 17.69%; vacuum-dried: 19.10%). Superior results in terms of textural properties were achieved in hydrogel models containing spray-dried and freeze-dried proteins. In general, hydrogel models exhibited elastic behavior rather than viscous properties; however, the magnitudes of elasticity varied. Furthermore, the success of gels containing hydrogel models containing spray-dried protein and locust bean gum in the bioactive compound delivery system was obvious compared with protein ones alone.

Protein composition and nutritional aspects of pea protein fractions obtained by a modified isoelectric precipitation method using fermentation.

Pea albumins are promising for their nutritional, biological, and techno-functional properties. However, this fraction is usually discarded in the industry due to its low protein content compared to globulin fraction and the presence of some anti-nutritional compounds. In the present study, we used an alternative method of pea protein extraction based on alkaline solubilization/isoelectric precipitation in which the reduction of pH was achieved by lactic acid fermentation using specific starters instead of mineral acids. Hence, the main objective of this study was to examine the protein profile and the content of anti-nutritional and nutritional active compounds in pea albumin-rich fractions obtained by the isoelectric extraction method without (control) or with fermentation with different lactic acid bacteria (Streptococcus thermophilus, Lactiplantibacillus plantarum, and their co-culture). Different pea cultivars (Cartouche, Ascension, and Assas) were used here for their differences in protein profile. The results revealed a higher total nitrogen content in albumin-rich fraction for fermented samples and, in particular, for co-culture. The majority of total nitrogen was determined as non-protein (~50%), suggesting the degradation of proteins by LAB to small peptides and amino acids, which were solubilized in the soluble fraction (albumin) as confirmed by size exclusion chromatography (SEC-HPLC) analysis. Moreover, the higher antioxidant activity of fermented albumin samples was attributed to the production of small peptides during extraction. Lactic acid fermentation also resulted in a significant reduction of trypsin inhibitor activity, α-galactoside, and phytic acid content of this fraction compared to control.

Efficacy of alginate and chickpea protein polymeric matrices in encapsulating curcumin for improved stability, sustained release and bioaccessibility

The present study compares the ubiquitously used alginate with seldom used chickpea protein as matrices for encapsulating curcumin, in terms of stability, in vitro release and bioaccessibility. Alginate and chickpea protein particles prepared via ionic gelation and isoelectric precipitation methods, respectively, were in the submicron range showing high encapsulation efficiencies of above 90%. Encapsulated particles stored in dark refrigerated conditions displayed greater stability of curcumin. In vitro release of curcumin from both encapsulated particles exhibited pH-dependent slow controlled release. However, alginate particles were more promising due to a protective role performed at gastric pH. The release profiles of curcumin from alginate and chickpea protein particles were best described by First order and Weibull models at pH 2 respectively, while those were well described by Higuchi and Zero order models at pH 6.8 respectively. Accordingly, release of curcumin from both encapsulated particles displayed diffusional controlled release at pH 2 while that from both particles showed diffusion-swelling controlled release at pH 6.8. Bioaccessibility of curcumin from both matrices after intestinal digestion was around 50% while that of free curcumin was approximately 18%. Overall, results point to alginate having an advantage over the chickpea protein matrix for safe efficacious oral delivery of curcumin. Thus, encapsulation of curcumin in alginate may be a promising method for the engineering of curcumin incorporated food with enhanced properties.

Komposisi Asam Amino Dari Ekstrak Kecambah Kacang Merah (Phaseolus vulgaris L) Setelah Tahap Deproteinasi

&#x0D; &#x0D; &#x0D; During the germination process, there is a degradation activity of reserve proteins in the seeds and releases short peptides and free amino acids. This study aimed to determine the amino acid composition of the red bean sprout extract after the deproteination stage. The deproteination stage is the stage of eliminating protein macromolecules that are dissolved in the extract so that short peptides and free amino acids are left in the extract. Red bean seeds were first germinated, made into flour, and extracted with distilled water, then deproteinized by the isoelectric precipitation method at pH 4.5. This protein macromolecular free extract(expected to contain free amino acids and short peptides) was then analyzed for its amino acid composition by the HPLC method. The results of the analysis of the composition of 15 types of amino acids in red bean sprout extract showed that the highest amino acid content was glutamic acid (1213,305 mg/kg), while the lowest amino acid content was tyrosine (118,245 mg/kg). The results also show phenylalanine as a type of essential amino acid with the highest levels compared to other essential amino acids. This shows that red bean sprout extract has the potential as a source of essential amino acids.&#x0D; &#x0D; &#x0D;

Physicochemical properties of different pea proteins in relation to their gelation ability to form lactic acid bacteria induced yogurt gel

Three commercial pea proteins and a laboratory sample (PL) were assessed for their physicochemical properties (subunit composition, secondary structure, surface hydrophobicity, solubility) and gelation properties (rheology, texture, intermolecular forces) in fermentation induced yogurt gel. The results showed that the dissociation of legumin was occurred in all three commercial pea proteins, accompanied by the formation of large protein aggregates. The contents of α-helix and β-sheet were significantly lower in the commercial pea proteins than PL (p < 0.05). However, commercial pea protein prepared by sour liquid processing method (PS) showed relatively higher solubility and β-sheet content than both of the two commercial samples prepared by alkali extraction isoelectric precipitation methods (PA). In addition, rheological properties results revealed that the gelation abilities of the three commercial pea proteins declined compared with the PL. Among all commercial pea protein-based yogurt gels, PS-based yogurt gel presented a higher hardness than PA-based yogurt gels. According to this study, the decreased gelation ability of commercial pea proteins could attribute to the dissociation of legumin and decrease in β-sheet structure, which weaken the hydrophobic force to form yogurt gels induced by lactic acid bacteria.

Influence of high-intensity ultrasound on physicochemical and functional properties of a guamuchil Pithecellobium dulce (Roxb.) seed protein isolate

In this study, the influence of ultrasound on the physicochemical and functional properties of guamuchil seed protein isolate (GSPI) was investigated. The GSPI was prepared by alkaline extraction and isoelectric precipitation method followed by treating with ethanol (95%), from defatted guamuchil seed flour. GSPI suspensions (10%) were sonicated with a probe (20 kHz) at 3 power levels (200 W, 400 W, 600 W) for 15 and 30 min, in addition, to control treatment without ultrasound. Moisture content, water activity, bulk and compact densities and the L*, a* and b* color parameters of the GSPI decreased due to the ultrasound. Glutelin (61.1%) was the main protein fraction in GSPI. Results through Fourier transform infrared and fluorescence spectroscopy showed that ultrasound modified the secondary and tertiary protein structures of GSPI, which increased the surface hydrophobicity, molecular flexibility and in vitro digestibility of GSPI proteins by up to 114.8%, 57.3% and 12.5%, respectively. In addition, maximum reductions of 11.9% in particle size and 55.2% in turbidity of GSPI suspensions, as well as larger and more porous aggregates in GSPI lyophilized powders were observed by ultrasound impact. These structural and physicochemical changes had an improvement of up to 115.5% in solubility, 39.8% in oil absorption capacity, while the increases for emulsifying, foaming, gelling, flow and cohesion properties of GSPI were 87.4%, 74.2%, 40.0%, 44.4%, and 8.9%, respectively. The amelioration of the functional properties of GSPI by ultrasound could represent an alternative for its possible use as a food ingredient in industry.

Corn protein isolate: Characteristic analysis, functional properties, and utilization in beverage formulation

The study demonstrates the analysis of novel protein isolated from corn oil cake. The protein has been extracted from the industrial by-product and was formulated to make out a supplement that could potentially solve the malnourished cases. The protein was extracted using isoelectric precipitation method. The functional properties of the extracted protein isolates that include its bulk density, flow properties, emulsifying properties, oil and water absorption capacity, and protein solubility were determined. Further instrumental analyses, including FTIR, SEM, XRD, and color analysis were performed to reveal the physical properties of proteins. After the study of proteins, the end product protein isolates were formulated into a protein-based beverage drink. At the end of the research, we perceived the potential of corn oil cake protein isolates in the role of alternative nutrition source and in new product development. Novelty impact statement Since there is an increased awareness on protein intake and the prevalence of protein malnutrition in developing and under developed countries, this research focuses on identifying novel protein sources to meet the increasing demand. In the present study, functional properties and utilization of corn protein isolates for beverage formulation was conducted. The results obtained in the study showcases the novelty of the research and clearly concludes that corn protein isolates are good to be used as food additives like foaming, emulsifying, oil-binding agent, and also it can be utilized as a protein supplement to prepare many protein enriched product.

Standardization and characterization of Himalayan wild apricot (geographical indicator) kernel press cake protein isolate and utilization for manufacture of gluten‐free pasta

The protein isolates were extracted from Himalayan wild apricot kernel press cake using isoelectric precipitation method. The extraction conditions were optimized using response surface methodology (RSM) with 10 different combinations of two independent variables (pH and temperature) for three responses (yield %, soluble protein %, and crude protein %). Temperature of 20°C and pH 10 were the optimum extraction conditions with recovery of about 36.52%. The protein isolates (2.5%, 5.5%, 7.5%, and 10.0%) were utilized for the production of gluten-free pasta (GFP). Incorporation of 5% protein isolates in the GFP was optimized as the best treatment which reported the highest cooking quality (less residue in cooking water and minimum cooking loss i.e., 4.30%). Furthermore, the FTIR spectra and SEM revealed higher quality which was further confirmed by In vitro protein digestibility, mineral contents, color, and texture profile analysis (TPA). Practical applications The developed protocol/technology will help the industrialists and researchers for utilization of byproducts for extraction of protein isolate and its value addition for development of gluten-free pasta.

Extraction of Plant Based Protein from Moringa oleifera Leaves using Alkaline Extraction and Isoelectric Precipitation Method

Extraction of Plant Based Protein from Moringa oleifera Leaves using Alkaline Extraction and Isoelectric Precipitation Method

دراسة تأثير الطحين والمركز البروتيني لبذور الترمس على الخصائص الفيزيائية والكيميائية والحسية للبسكويت

The purpose of this study was to determine the effect of lupine flour (L.f) and lupine protein concentrate (L.P.C) incorporation on chemical, nutritional and sensual qualities characteristics of biscuit (L.P.C) was prepared by isoelectric precipitation method. A standard recipe for biscuit preparation by wheat patent flour used as the control. Wheat flour in the control treatment was replaced with (L.f) and (L.P.C) at levels 10, 20 &amp; 30%. Chemical composition of (L.f), (L.P.C) and biscuit treatments were studied. Results showed that protein contents were 35.35 &amp; 75.80% for (L.F) and (L.P.C), respectively. While they amounted to 14.70, 16.16 &amp; 18.61% for (L.f) incorporated biscuits and 15.20, 18.09 &amp; 21.08% for (L.P.C) incorporated biscuits at the substitution levels studied, respectively compared 12.43% control. Results also indicated contents of total dietary fibers and tannins in (L.f),( L.P.C) and biscuits prepared. Sensory evaluation of biscuit treatments revealed that there was significant decrease at substitution level up to 30% of (L.f) except color score, while all scores of sensory properties were improved significantly at all substitution levels of (L.P.C). Spread ratio was affected adversely by incorporation of (L.f) and slightly when (L.P.C) used. Results showed a reduction in biscuit tenderness during storage. Reverse to the above statement with 30% incorporation of (L.f) while increased at (L.P.C) treatments. The study demonstrated that (L.f) and (L.P.C) can be incorporated into biscuits formulation by replacing up to 20, &amp; 30% of wheat flour control 12.43%, respectively to increase dietary fiber and protein contents.

Physicochemical and emulsifying properties of protein isolated from Phlebopus portentosus

Edible mushroom proteins have attracted increasing interest due to their high content and nutritional quality. In the present work, Phlebopus portentosus protein isolate (PPI) was extracted from P. portentosus fruiting bodies using alkali extraction and isoelectric precipitation method, and the physicochemical and emulsifying properties of PPI were systematically investigated. PPI had a good balance of essential amino acids, but showed low solubility in water. Therefore, a protein nanoparticulation strategy was used to prepare stable PPI nanoparticle (PPIP) dispersions. PPIP showed an average diameter of 225.91 nm, an oil-in-water three-phase contact angle (θo/w) of 95.62°, and fast adsorption behavior at the oil-water interfaces. The near-neutral wettability and high interfacial ability facilitate PPIP as a single emulsifier to fabricate a double Pickering emulsion via the one-step homogenization. The properties of PPIP-stabilized double emulsions were dependent on the protein concentration and oil content. For example, an increase in protein concentration resulted in the decrease of small internal droplet number, droplet size, and storage modulus; an increase in oil content also led to the decrease in the droplet size. These results suggest that PPI has a great potential to be used as emulsifiers for preparing double emulsions.

Nutritional and functional properties of flour and protein isolates from germinated Solojo Cowpea Vigna unguiculata (l.) Walp.

Nutritional and functional properties of flours derived from two (2) varieties of cowpea, Dark-Ash Solojo (DAS) and Brown Solojo (BS) were studied before and after dehulling of the germinated seeds. Ungerminated seeds were used as the control. Protein isolates from dehulled defatted solojo cowpea seeds were prepared using isoelectric (CPIA) procedure. Dehulled samples had a higher protein solubility compared with germinated and control samples. Both varieties of cowpea (DAS and BS) investigated were soaked in distilled water and germinated at varying periods i.e. 0, 6, 24, 36, 48 and 72hrs. Protein isolates were obtained from the treated and processed samples by isoelectric precipitation method which was subsequently followed by proximate and anti-nutritional analyses. Functional properties were also analysed which include Water Absorption Capacity (WAC) and Oil Absorption Capacity (OAC) of the protein isolates using standard methods. Amino acids and molecular weight of the protein isolates were determined by amino acid analyser and sodium-dodecyl-sulphate-polyacrylamide-gel-electrophoresis. Surface morphology, functional group and thermal properties were determined for protein isolates by scanning electron microscopy, Fourier Transform Infrared (FTIR) spectrometry and differential scanning calorimetry, respectively. Data were analysed by descriptive statistics and ANOVA at α0.05. The moisture content, crude protein, crude fat, crude fibre and total ash of DAS ranged from 9.00-11.40, 24.82-31.00, 1.56-2.66, 1.43-1.67, and 3.20-4.14%, respectively; while those of BS flours ranged from 7.10-9.50, 24.90-30.14, 1.17-2.37, 1.06-1.52 and 3.05-3.93%, respectively. The protein contents for DAS were 81.57±0.53, 86.44±0.84, 89.39±1.51, 90.23±0.53, 91.81±0.77 and 94.85±0.86, while for BS were 84.39±0.39, 85.44±0.56, 90.05±0.10, 90.47±0.89, 92.78±0.28 and 95.81±0.19% for 0, 6, 24, 36, 48 and 72 hrs, respectively. On dehulling, the fat absorption capacities of samples were reduced and the differences were statistically significant. The emulsification capacities of control samples ranged from 50 to 198 ml oil emulsified per gram of sample. On germination and dehulling, the emulsification capacities, activities and stabilities of samples increased significantly. There were increases in foaming capacities and reduction in foam stabilities of the two cowpea varieties investigated on germination and dehulling. Thus, the study showed that germination and dehulling improved the functional properties of the Solojo Cowpea studied.

Physicochemical and Functional Properties of Flour and Protein Isolates from Two (2) Solojo Cowpea (Vigna Unguiculata L. Walp) Varieties in Nigeria

Protein isolates from dehulled defatted solojo cowpea seeds were prepared using isoelectric (CPIA) procedure. Two varieties of cowpea, Dark-Ash Solojo (DAS) and Brown Solojo (BS) were cleaned and divided into six portions. Both varieties of cowpea (DAS and BS) investigated were soaked in distilled water and germinated at varying periods i.e. 0, 6, 24, 36, 48 and 72hrs. Protein isolates were obtained from the treated and processed samples by isoelectric precipitation method which was subsequently followed by proximate and anti-nutritional analyses. Functional properties were also analysed which include Water Absorption Capacity (WAC) and Oil Absorption Capacity (OAC) of the protein isolates using standard methods. Amino acids and molecular weight of the protein isolates were determined by amino acid analyser and sodium-dodecyl-sulphate-polyacrylamide-gel-electrophoresis. Surface morphology, functional group and thermal properties were determined for protein isolates by scanning electron microscopy, Fourier Transform Infrared (FTIR) spectrometry and differential scanning calorimetry, respectively. Data were analysed using design expert software and Analysis of Variance (ANOVA) was carried out at α0.05. The moisture content, crude protein, crude fat, crude fibre and total ash of DAS ranged from 9.00-11.40, 24.82-31.00, 1.56-2.66, 1.43-1.67, and 3.20-4.14%, respectively; while those of BS flours ranged from 7.10-9.50, 24.90-30.14, 1.17-2.37, 1.06-1.52 and 3.05-3.93%, respectively. The protein contents for DAS were 81.57±0.53, 86.44±0.84, 89.39±1.51, 90.23±0.53, 91.81±0.77 and 94.85±0.86, while for BS were 84.39±0.39, 85.44±0.56, 90.05±0.10, 90.47±0.89, 92.78±0.28 and 95.81±0.19% for 0, 6, 24, 36, 48 and 72 hrs, respectively.

Effective valorization of bio-processed castor kernel meal based fish feed supplements concomitant with oil extraction processing industry: A prolific way towards greening of landscaping/environment

The prime demand for expansion of feed-based aquaculture is the quest for new protein-rich ingredients to accomplish the global food and nutritional securities. Simultaneously, consistent production of agro-industrial wastes and their disposal is a major issue, although, the better nutritional profile of these wastes fostering a way forward to valorize in animal/fish feed. The present study was proposed to ensure the valorization of the castor oil industry’s residues i.e. castor cake or meal by standardizing the process for the preparation of protein isolate with the help of iso-electric precipitation method and subsequently utilizing them in fish feed. Maximum recoveries and protein content (P<0.05) for the castor protein isolate (CPI) were achieved at 12.0/5.0 pH combination. The nutritional quality of the protein isolate (CPI) was superior to the kernel meal and comparable to standard protein (egg white) and soybean protein isolates (SPI). In vivo evaluation of CPI was carried out in Labeo rohita fingerlings by feeding the different graded dietary level of CPI with substitution of 0%, 25%, 50%, 75%, and 100% soybean protein isolate based on equivalency of the protein. The diets were designated as control, CPI 25 , CPI 50 , CPI 75 , CPI 100 , respectively. The CPI contributed 0%, 11.83%, 22.78%, 33.28% and 43.91% of the total protein in experimental diets. Dietary castor protein isolate significantly affected the growth rate, feed conversion and nutrient utilization indices in L. rohita fingerlings. Maximum observed growth indices were in fish fed with control and CPI 25 , CPI 50 , and CPI 75 diets whereas, minimum in CPI 100 fed group. Dietary CPI did not affect the body indices, survival and body composition in rohu fingerlings. Based on the results, it can be concluded that castor protein isolate would be a valuable protein-rich ingredient for fish feed and 75% substitution of soy protein isolate with castor protein isolate could be possible without any harmful effects on growth, feed conversion, nutrient utilization and survival. • The method for preparation of castor protein isolate (CPI) was standardized. • The pH condition of 12.0/5.0 exhibited the best recoveries and protein content of CPI. • The nutritional value of CPI was superior to meal and comparable to egg white. • 75% substitution of soy protein isolate (SPI) with CPI is possible in carp diet. • CPI would be a potential protein source in animal/fish feed.

Jackfruit (Artocarpus heterophyllus Lam) leaf as a new source to obtain protein hydrolysates: Physicochemical characterization, techno-functional properties and antioxidant capacity

Physicochemical, techno-functional properties and antioxidant capacity of Jackfruit leaf protein concentrate (LPC). And its hydrolysates were evaluated. LPC was obtained using the isoelectric precipitation method assisted by high hydrostatic pressure. LPC and its hydrolysates with pepsin (H-Pep) and pancreatin (H-Pan) at different interval times were characterised by colour, foaming and emulsifying properties. The antioxidant capacity through in vitro tests, such as DPPH+ and ABTS+ radical scavenging activity was also evaluated. The degree of hydrolysis (DH) for H-Pep and H-Pan ranged from 1.78 to 3.44 to 6.12–9.21%. The enzymatic hydrolysis significantly increased (p < 0.05) the L* value of all the hydrolysates concerning the LPC. However, the H-Pep presented lower ΔE (p < 0.05) regarding the H-Pan, this could be related to the high L* values presented in the samples. The solubility of the hydrolysates was significantly higher (p < 0.05) than the LPC in all the tested pH (2.0–10.0) values (except for H-Pep at pH 10.0), reaching solubility values of 19–41 and 60–98% from pH 4.0 to 10.0 for H-Pep and H-Pan, respectively. The increase of solubility was associated with high emulsifying and foaming properties compared with LPC. The best emulsifying and foaming properties were presented at 180 and 60 min of H-Pan, respectively. The antioxidant capacity revealed that the H-Pan at 120 min of proteolysis exhibited high antioxidant properties. The values for DPPH+ and ABTS+ were 72.38% at 0.1 mg/mL and 98.20% at 0.8 mg/mL, respectively. The results suggest that type of enzyme and hydrolysis time determined the physicochemical, techno-functional properties, and antioxidant capacity of hydrolysates.

Protein quality of dehulled-defatted African mesquite bean (Prosopis africana) flour and protein isolates

In this study, the protein quality of dehulled-defatted African mesquite bean (Prosopis africana) flour and protein isolates obtained using micellization and isoelectric precipitation methods were investigated. The dominant amino acids in the dehulled-defatted Prosopis africana flour and protein isolates included aspartic acid, glutamic acid, leucine and arginine, while the first, second and third limiting amino acids were methionine, threonine and valine/tryptophan, respectively. Amino acid profiles and scores, classifications and ratios, predicted protein efficiency ratios (1.79–2.89), biological (12.61–37.97%) and net protein (15.77–50.84%) values, essential amino acid (63.94–87.02%) and nutritional (23.33–70.78%) indexes showed that the dehulled-defatted P. africana flour and its protein isolates were of high protein quality and could be employed in complementing cereal-based and other similar foods whose proteins are deficient in lysine. Isoelectric precipitation method yielded protein with better nutritional quality compared to the micellization method. P. africana flour and protein isolates could therefore be exploited as protein sources in food formulation for tackling protein malnutrition in Africa.

Physicochemical properties, protein digestibility and thermal stability of processed African mesquite bean (Prosopis africana) flours and protein isolates

The physicochemical, in vitro protein digestibility and thermal properties of dehulled (DPAF) and dehulled–defatted (DDPAF) African mesquite bean (Prosopis africana) flours and protein isolates produced by micellization and isoelectric precipitation were evaluated. Isoelectric precipitation method gave higher yield of protein isolate (30.46%) with higher protein content (81.34%) compared to the micellization which yielded 7.95% and 72.04%, respectively. Significant (p < 0.05) differences occurred among the total colour difference (23.63–53.12), whiteness (40.17–67.78), yellowness (36.81–49.26), browning (− 123.22 to 471.59) and flour colour (26.63–55.04) indexes and functional properties except dispersibility of the samples, indicating the effects of defatting and protein extraction methods. Micellized protein isolate recorded the highest oil (322%), water (300%) absorption and emulsion (64.67%) capacities, while the isoelectric precipitated protein had the highest protein solubility (81.75%). The protein isolates exhibited lower foam stability than the flours with micellized protein being the least. Thermal properties of the flours and protein isolates also varied with defatting and extraction methods. The dehulled P. africana flour and isoelectric precipitated protein showed single endothermic peaks with higher thermal stability compared to the dehulled–defatted flour and micellized protein which had two endothermic peaks. Flours and protein isolates showed in vitro protein digestibility between 76.44 and 80.00%, with micellized protein exhibiting the highest digestibility. Knowledge of the physicochemical properties of P. africana seed products would enhance their utilization in various food formulations, thereby contributing to food security in Africa.