Alkaline Solubilization Research Articles

Enzymolysis of Azolla pinnata protein concentrate: Effect of protease types and hydrolysis extents on the physicochemical, techno-functional and biological properties

Azolla pinnata is an underutilised fern and has been found to be a highly promising and sustainable source, making it a potential new plant-based protein source that can be used as a functional food ingredient. Therefore, the present work produced Azolla pinnata fern protein concentrate (AFPC) through alkaline solubilisation with isoelectric precipitation and investigated the effect of different proteases at varying degree of hydrolysis (DH) on the physicochemical, techno-functional properties and biological activities of Azolla fern protein hydrolysates. Enzymolysis with all proteases decreased the hydrophobicity, denaturation temperature and secondary structures (β-sheet and α-helix) as the DH increased. Furthermore, the techno-functional properties including water and oil holding capacities, emulsion properties and foam stability were significantly reduced with increasing the DH, except for solubility and foaming capacity. Additionally, the pH had a positive correlation with all the techno-functional properties, except for water holding capacity. Hydrolysis with all proteases had a positive effect on the antioxidant and antibacterial activities. The partially hydrolysed protein with alcalase showed excellent techno-functional and antioxidant properties, while excellent antibacterial activity was observed for hydrolysate produced by flavourzyme under extensive hydrolysis. The current findings pave the way for the application of Azolla fern protein hydrolysates as promising and sustainable plant-based peptide to be utilised as nutraceutical and functional food ingredients.

Earth Worming-An Evaluation of Earthworm (Eisenia andrei) as an Alternative Food Source.

Aside from their bioremediation roles, little is known about the food and feed value of earthworms. In this study, a comprehensive evaluation of the nutritional composition (proximate analysis and profiles of fatty acids and minerals) and techno-functional properties (foaming and emulsion stability and capacity) of earthworm (Eisenia andrei, sourced in New Zealand) powder (EAP) were investigated. Lipid nutritional indices, ω6/ω3, atherogenicity index, thrombogenicity index, hypocholesterolemic/hypercholesterolemic acid ratio, and health-promoting index of EAP lipids are also reported. The protein, fat, and carbohydrate contents of EAP were found to be 53.75%, 19.30%, and 23.26% DW, respectively. The mineral profile obtained for the EAP consisted of 11 essential minerals, 23 non-essential minerals, and 4 heavy metals. The most abundant essential minerals were potassium (8220 mg·kg-1 DW), phosphorus (8220 mg·kg-1 DW), magnesium (744.7 mg·kg-1 DW), calcium (2396.7 mg·kg-1 DW), iron (244.7 mg·kg-1 DW), and manganese (25.6 mg·kg-1 DW). Toxic metals such as vanadium (0.2 mg·kg-1 DW), lead (0.2 mg·kg-1 DW), cadmium (2.2 mg·kg-1 DW), and arsenic (2.3 mg·kg-1 DW) were found in EAP, which pose safety considerations. Lauric acid (20.3% FA), myristoleic acid (11.20% FA), and linoleic acid (7.96% FA) were the most abundant saturated, monounsaturated, and polyunsaturated fatty acids, respectively. The lipid nutritional indices, such as IT and ω-6/ω-3, of E. andrei were within limits considered to enhance human health. A protein extract derived from EAP (EAPPE), obtained by alkaline solubilisation and pH precipitation, exhibited an isoelectric pH of ~5. The total essential amino acid content and essential amino acid index of EAPPE were 373.3 mg·g-1 and 1.36 mg·g-1 protein, respectively. Techno-functional analysis of EAPPE indicated a high foaming capacity (83.3%) and emulsion stability (88.8% after 60 min). Heat coagulation of EAPPE was greater at pH 7.0 (12.6%) compared with pH 5.0 (4.83%), corroborating the pH-solubility profile and relatively high surface hydrophobicity (1061.0). These findings demonstrate the potential of EAP and EAPPE as nutrient-rich and functional ingredients suitable as alternative food and feed material. The presence of heavy metals, however, should be carefully considered.

Whey protein isolate and kraft lignin multifunctional films for potential food packaging application: UV block and antioxidant potential

Kraft lignin (KL) is a promising additive for obtaining multifunctional biodegradable packaging. However, the hydrophobic properties of lignin hinder its dispersion in hydrophilic matrices. The prior alkaline solubilization of lignin before adding it to the filmogenic dispersion could be an alternative to overcome this limitation. In this sense, this study aimed to produce whey protein isolate (WPI) multifunctional films incorporated with different concentrations of KL, ranging from 0% to 8%, previously solubilized in alkaline solution, and characterize them in terms of morphological, molecular, mechanical, optical, hydrophobicity, thermal, sealability, antioxidant, and UV-blocking properties. The prior solubilization of KL allowed the obtainment of homogeneous films of a dark color with greater resistance to fracture, higher hydrophobicity, higher glass transition temperature than the control film, and a slightly greater thermal stability: the initial and maximum degradation temperature of 166.1 °C and 305.3 °C, respectively. Lignin presence in the matrix also gave the films functionalities compared to the control: the films added with 2% of KL blocked 95% of UVA and 100% UVB radiation without impairing the passage of visible light, and the films with 8% of KL showed 34.69% of antioxidant activity in DPPH analysis. However, the films were not heat sealable, which was an undesirable outcome. Nevertheless, lignin solubilization in alkali proved to be an efficient methodology for producing multifunctional WPI films, with potential application on foods susceptible to oxidation.

Functional and physicochemical properties of protein from giant squid (Dosidicus gigas) extracted using foam-aided pH-shift processing.

Jumbo squid (Dosidicus gigas) is a commercially valuable mollusk in Mexico; 80% of its body is edible. Despite the high protein content (∼18%) and low cholesterol content of this species, its high proteolytic activity (microbial and endogenous enzymes) induces protein degradation and consequent reduction in functional properties from a structural viewpoint. Gelation capacity (texture profile of the gels obtained), solubility, water holding capacity, foaming capacity, emulsification capacity, and emulsion stability were evaluated in protein concentrates obtained by foam-aided pH-shift processing: (A) myofibrillar protein extraction with distilled water and no pH-shifting; (B) alkaline solubilization and isoelectric precipitation; (C) acidic solubilization and isoelectric precipitation; and (D) process A and isoelectric precipitation. Process B showed superior gelation capacity, D had high emulsion stability across a wide range of pH values (4.0-8.0) and C lower plate counts of aerobic mesophilic. Therefore, all three alternative extraction processes showed techno-functional advantages. PRACTICAL APPLICATION: Jumbo squid is an abundant protein source in México, most of which is exported. Functional and physicochemical properties of muscle protein were improved by pH-shift processing. The recovered protein showed modifications of technological properties, using one of the methods described can lead to produce a protein extract with the most desirable attributes, such as foaming, emulsifying, or gelling capacities. The functional and physicochemical properties of protein from squid can be enhanced by selecting a certain pH-shift processing, depending on the desirable use. There is a broad perspective on the use of these protein extracts as ingredients or additives.

Impact of Red Sludge Dumps, Originating from Industrial Activity, on the Soil and Underground Water

In the aluminum industry, one of the most sensitive economic and environmental problems is the management of resulting waste such as slag, ash and sludge, which become potential sources of pollution. Red sludge, which results from the aluminum industry, is a mixture made up of different forms of iron and aluminum oxides, sodium and aluminum silicates, various titanium compounds, constituted in the residue left after the alkaline solubilization of alumina. The Purpose of this research is to quantify the environmental aspects involved in the storage of sludge in a landfill that has an area of 381,189 square meters and is located in the hearth of a former ballast tank in the western industrial area of the town of Oradea, Romania. The objective of the research was to determine the impact of red sludge dumps, which originated from industrial activity, on the soil and groundwater. The degree of degradation of the soil cover was highlighted by analyzing a number of 12 soil samples (4 collection points, at 3 depths). A total of 14 samples (7 samples on 2 depths) were investigated to monitor the migration mode of the sludge in the structure of the dam. In order to monitor the quality of groundwater, samples from 3 observation boreholes were analyzed. Soil monitoring results did not indicate values of the analyzed parameters above the values imposed by the national legislation on soil quality. Since the dumps were not waterproofed, the quality parameters of the water from the observation boreholes were exceeded, and gravity caused the water to drain into the underground water network in the area. Based on the samples from the observation boreholes, several measurements exceeded allowable values: pH values of the water sample taken from upstream of the dump exceeded the value limits by about 7%, and both upstream and downstream, water samples indicate an excess of 13.60% in the aluminum indicator, 267% in the sulfate ion, and 417% in the sodium ion. This shows a risk of pollution which requires additional monitoring.

In Vitro Digestibility, Biological Activity, and Physicochemical Characterization of Proteins Extracted from Conventionally and Organically Cultivated Hempseed (Cannabis sativa L.).

The proteins from two conventionally (CC1 and CC2) and one organically cultivated (OC) hempseed samples were extracted (by alkaline solubilization followed by isoelectric precipitation) and compared in terms of their physicochemical, digestibility and in vitro bioactivity properties. The OC hempseed had higher total protein and lower nonprotein nitrogen content. Protein extracts showed bimodal particle size distributions, with OC showing the smallest and CC1 the largest mean particle diameter (d(0.5)), i.e., 89.0 and 120.0 µm, respectively. Chromatographic analysis showed similar protein profiles for all three protein extracts. The protein extracts were subjected to in vitro simulated gastrointestinal digestion (SGID). Degree of hydrolysis (DH) measurement showed that the highest extent of digestion upon SGID was associated with CC1 (11.0 ± 1.5%), which also had the lowest in vitro antioxidant activity. Only the OC and OC digested samples had lipase inhibitory activity. The results indicate that the cultivation method impacted the composition, physicochemical, digestibility, and biofunctional properties of hempseed proteins.

Structure-Function Guided Extraction and Scale-Up of Pea Protein Isolate Production.

The lack of adequate guidance and control of the extraction conditions as well as the gap between bench- and industrial-scale production, contributes to the poor functionality of commercial pea protein isolate (cPPI). Therefore, pea protein extraction conditions were evaluated and scaled up to maximize protein purity and yield, while maintaining structural integrity, following mild alkaline solubilization with isoelectric precipitation and salt solubilization coupled with membrane filtration. Both extraction methods resulted in high protein yield (>64%) and purity (>87%). Structure-function characterization illustrated the preserved structural integrity of PPI samples and their superior solubility, gelation, and emulsification properties compared to cPPI. Results confirmed, for the first time, that double solubilization at mild pH (7.5) can replace single solubilization at high alkalinity and achieve a similar yield while preserving structural integrity. Additionally, this study demonstrated, the scalability of the benchtop salt extraction coupled with ultrafiltration/diafiltration. Scaling up the production eliminated some structural and functional differences between the salt-extracted PPI and pH-extracted PPI. Scaling-up under mild and controlled conditions resulted in partial denaturation and a low degree of polymerization, coupled with the superior functionality of the produced isolates compared to cPPI. Results of this work can be used as a benchmark to guide the industrial production of functional pea protein ingredients.

Properties of Protein Isolates from Marine Hydrobionts Obtained by Isoelectric Solubilisation/Precipitation: Influence of Temperature and Processing Time.

Protein isolates were obtained from marine hydrobionts by the method of isoelectric precipitation with a preliminary stage of protein alkaline solubilisation. Northern blue whiting was chosen as the raw material. Various technological modes of the solubilisation stage were used: the temperature of the reaction mixture was 4 or 20 °C, and the duration was 4 or 16 h. The yield of the product was 44-45% with a high content of the main component (protein) equal to about 95%. It has been shown that a decrease in the temperature and duration of the alkaline solubilisation stage provides the production of protein isolates with good technological properties, a low solubility, high swelling and high emulsifying ability, necessary for its use in the production of functional food products, including therapeutic and prophylactic effects. These technological properties are explained by a change in the composition and structure of the protein, the change being an increase in the content of essential amino acids and the proportion of α-helices in the polypeptide chain. The main patterns obtained will be used to obtain protein isolates from marine molluscs.

Human growth hormone inclusion bodies present native-like secondary and tertiary structures which can be preserved by mild solubilization for refolding

BackgroundNative-like secondary structures and biological activity have been described for proteins in inclusion bodies (IBs). Tertiary structure analysis, however, is hampered due to the necessity of mild solubilization conditions. Denaturing reagents used for IBs solubilization generally lead to the loss of these structures and to consequent reaggregation due to intermolecular interactions among exposed hydrophobic domains after removal of the solubilization reagent. The use of mild, non-denaturing solubilization processes that maintain existing structures could allow tertiary structure analysis and increase the efficiency of refolding.ResultsIn this study we use a variety of biophysical methods to analyze protein structure in human growth hormone IBs (hGH-IBs). hGH-IBs present native-like secondary and tertiary structures, as shown by far and near-UV CD analysis. hGH-IBs present similar λmax intrinsic Trp fluorescence to the native protein (334 nm), indicative of a native-like tertiary structure. Similar fluorescence behavior was also obtained for hGH solubilized from IBs and native hGH at pH 10.0 and 2.5 kbar and after decompression. hGH-IBs expressed in E. coli were extracted to high yield and purity (95%) and solubilized using non-denaturing conditions [2.4 kbar, 0.25 M arginine (pH 10), 10 mM DTT]. After decompression, the protein was incubated at pH 7.4 in the presence of the glutathione-oxidized glutathione (GSH-GSSG) pair which led to intramolecular disulfide bond formation and refolded hGH (81% yield).ConclusionsWe have shown that hGH-IBs present native-like secondary and tertiary structures and that non-denaturing methods that aim to preserve them can lead to high yields of refolded protein. It is likely that the refolding process described can be extended to different proteins and may be particularly useful to reduce the pH required for alkaline solubilization.

Eco-Efficiency of Mealworm (Tenebrio molitor) Protein Extracts

The potential of edible insects as a novel ingredient in high value-added products has been investigated to find alternatives to conventional protein sources. Low acceptability of entomophagy is the main challenge, but the development of insect protein-based food products could improve consumer perception. Nevertheless, while insect rearing has a low environmental impact, there are no studies on environmental performance related to the production of insect protein extracts. In this work, Tenebrio molitor (TM) protein extracts were produced by protein alkaline solubilization (one or two steps) with or without isoelectric precipitation, and the global warming potential (GWP) related to the different protein extracts was calculated. The optimal lipid extraction rate was 86.9% using a hexane: ethanol ratio of 1:2. Protein extraction and purification rates ranged from 54.7 to 94.4% and 80.0 to 49.4%, respectively. Depending on the protein purification and allocation method applied, the GWP of a TM protein extract was 3,050 to 10,871 kg CO2 eq. per ton of the extract produced. Eco-efficiency scores associated to TM proteins extracts were between those published with plant-based and animal-based protein sources, confirming the interesting environmental performance of insect-derived protein ingredients.

A Comprehensive Comparison of Different Selenium Supplements: Mitigation of Heat Stress and Exercise Fatigue-Induced Liver Injury.

This study aimed to compare the protective effects of different selenium supplements against heat stress and exercise fatigue-induced liver injury and to investigate the potential mechanisms of action. Selenium-enriched soybean protein (SePro), selenium-enriched soybean peptides (SePPs), and selenomethionine (SeMet) are organic selenium supplements in which selenium replaces the sulfur in their sulfur-containing amino acids. Common peptides (PPs) are obtained by enzymatic hydrolysis of soybean protein which was extracted from common soybean. The SePPs with higher hydrolysis degree and selenium retention were isolated via alkaline solubilization and acid precipitation and the enzymatic hydrolysis of alkaline protease, neutral protease, and papain. The results showed that SePPs could significantly increase the antioxidant levels in rats, inhibit lipid peroxidation, and reduce liver enzyme levels in rat serum, while the histological findings indicated that the inflammatory cell infiltration in the liver tissue was reduced, and new cells appeared after treatment with SePPs. Moreover, SePPs could increase glutathione (GSH) and GSH peroxidase (GSH-Px) in the liver, as well as protect the liver by regulating the NF-κB/IκB pathway, prevent interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α) release in the liver. The SePPs displayed higher antioxidant and anti-inflammatory activity in vivo than SePro, SeMet, Sodium selenite (Na2SeO3), and PPs. Therefore, SePPs could be used as a priority selenium resource to develop heatstroke prevention products or nutritional supplements.

Comparison of the physicochemical and functional properties of flour and protein isolate from moringa (Moringa oleifera Lam.) leaves

ABSTRACT The physicochemical and functional properties of flour (MF) and a protein isolate (MPI) obtained from moring leaves were evaluated and compared. These properties were evaluated and compared with a commercial soybean protein isolate (SPI). MPI was obtained by alkaline solubilization at pH 11.5 and isoelectric precipitation at pH 4.5. The protein content of MPI was 75.8%, with a yield of 6.5% when obtained by lyophilization. Electrophoresis analysis confirmed the presence of proteins between 8 and 120 kDa, and FTIR analysis confirmed the yield of MPI and the decrease of non-protein constituents, such as carbohydrates. The MF showed good gelation properties [5 mL (100%) at 14% (w/v) flour]. MPI showed even better gelling properties (10% to 78%) than SPI and similar water and oil absorption capacities (WAC and OAC) (3 g g-1 and 1.5 g g-1 respectively) as SPI. The pH had a significant influence on these properties. It can be concluded that MPI is an important protein source and may be a viable alternative as a functional food ingredient comparable to SPI in some properties such as WAC, OAC, and emulsion stability at low pH.

Ultrasound-assisted alkaline pH-shift process effects on structural and interfacial properties of proteins isolated from shrimp by-products

This study investigated the effects of alkaline pH-shift processing (pH: 12, 12.5 and 13) combined with ultrasonication (300 W; 0, 10, 20, and 30 min) on the yield and functional characteristics of shrimp proteins. Ultrasound assistant pH-shift processing resulted in a significantly higher protein recovery than the alkaline pH-shifting as maximum protein recovery was obtained at pH 12.5 in combination with sonication for 30 min (25.12%). Applying ultrasonication during the alkaline solubilization remarkably (P < 0.05) decreased zeta potential and particle size of the recovered shrimp proteins while increasing their surface hydrophobicity, fluorescence intensity, and reactive sulfhydryl content. The combination led to the denaturation of the recovered proteins with a change in their α-helices, β-sheet, random coil and β-turn content. Foaming and emulsifying characteristics of the shrimp proteins were remarkably (P < 0.05) affected by using the combined treatment, however, the progress level was dependent on the ultrasonication time and the solubilization pH. The highest value in emulsifying activity and foaming capacity was obtained in the sample extracted at pH 12.5 in combination with ultrasound for 20 min (300 W). Altogether, applying ultrasonication during the pH-shift processing can help protein isolation from shrimp peeling by-products but the combination should be carefully tuned to achieve maximum protein functionality.

Application of emerging technologies to obtain legume protein isolates with improved techno-functional properties and health effects.

Current demand of consumers for healthy and sustainable food products has led the industry to search for different sources of plant protein isolates and concentrates. Legumes represent an excellent nonanimal protein source with high-protein content. Legume species are distributed in a wide range of ecological conditions, including regions with drought conditions, making them a sustainable crop in a context of global warming. However, their use as human food is limited by the presence of antinutritional factors, such as protease inhibitors, lectins, phytates, and alkaloids, which have adverse nutritional effects. Antitechnological factors, such as fiber, tannins, and lipids, can affect the purity and protein extraction yield. Although most are removed or reduced during alkaline solubilization and isoelectric precipitation processes, some remain in the resulting protein isolates. Selection of appropriate legume genotypes and different emerging and sustainable facilitating technologies, such as high-power ultrasound, pulsed electric fields, high hydrostatic pressure, microwave, and supercritical fluids, can be applied to increase the removal of unwanted compounds. Some technologies can be used to increase protein yield. The technologies can also modify protein structure to improve digestibility, reduce allergenicity, and tune technological properties. This review summarizes recent findings regarding the use of emerging technologies to obtain high-purity protein isolates and the effects on techno-functional properties and health.

Improved Refolding of a Human IgG1 Fc (CH2-CH3) Scaffold from Its Inclusion Body in E. coli by Alkaline Solubilization.

Recently, we developed a platform strategy for hinge-deficient human immunoglobulin G1 (IgG1) Fc fusion as a non-immunostimulatory Fc fusion system. As a starting point to establish a promising approach for generating hinge-deficient Fc fusion proteins in Escherichia (E.) coli, we selected a CH2-CH3 scaffold as a model protein for evaluation. Recombinant CH2-CH3, expressed as inclusion bodies, was solubilized with various denaturants (urea, sarkosyl, sodium dodecyl sulfate (SDS), 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS), or Triton X-100) in neutral (phosphate-buffered saline (PBS), pH 8) or alkaline (50 or 500 mM N-cyclohexyl-3-aminopropanesulfonic acid (CAPS), pH 11) buffer at 25 °C. Similar to the authentic CH2-CH3 produced in Chinese hamster ovary (CHO) cells, all denaturants, except urea in CAPS buffer but not in PBS, were found to elicit the dimer formation of solubilized CH2-CH3 on SDS-polyacrylamide gel electrophoresis (PAGE). After dialysis with PBS, sarkosyl-soluble CH2-CH3 inclusion bodies were successfully purified using protein G-Sepharose, indicating their successful refolding. Compared to the purified CH2-CH3 from its sarkosyl-soluble inclusion bodies in neutral buffer, that in 500 mM CAPS alkaline buffer revealed substantial structure-related similarities, such as secondary structures and thermal stabilities, as measured by circular dichroism spectroscopy, to authentic CH2-CH3. Native PAGE analysis also supported the above data. Therefore, solubilization at alkaline pH is an essential factor that promotes the refolding of CH2-CH3. Dimer formation of CH2-CH3 on SDS-PAGE may act as a surrogate marker for its protein refolding status. Our observations may provide important hints toward downstream processing of Fc-fusion production in E. coli.

Enhancing Lignin Dispersion and Bioconversion by Eliminating Thermal Sterilization

Thermal sterilization is widely applied in fermentation to ensure a pure culture. In this study, a facile and energy-efficient strategy by eliminating thermal sterilization (ETS) was unveiled for upgrading lignin bioconversion. Through alkaline solubilization and neutralization, lignin dispersion in aqueous fermentation media was significantly enhanced by ETS. Small-angle X-ray scattering and dynamic light scattering analyses indicated that the lignin colloid size was dramatically reduced. Compared to 20.5 wt % lignin precipitation during the conventional thermal sterilization, precipitated lignin was not observed within the ETS medium. 31P NMR characterization demonstrated an 11.7% increase of phenolic OH in ETS lignin. Ionization of phenolic OH presented more negatively charged groups, strengthening electrostatic repulsion, resulting in smaller colloidal particles. Interestingly, the pure culture of Rhodococcus opacus PD630 was achieved within the ETS medium due to the lack of lignin degradation ability with most natural microbes. R. opacus PD630 cell amount, lignin degradation, and lipid production by ETS increased by 330, 16.6, and 20.7%, respectively. Overall, an energy-efficient ETS strategy that promoted lignin dispersion and bioconversion significantly is reported in this study.

Monitoring the Aroma Profile During the Production of a Pea Protein Isolate by Alkaline Solubilization Coupled with Isoelectric Precipitation

The aroma profile was monitored during an optimized pH-extraction method (alkaline solubilization coupled with isoelectric precipitation) to produce pea protein isolates (PPIs). Samples were taken at different steps throughout the protein extraction. The aroma compounds were isolated from these samples using solvent-assistant flavor evaporation (SAFE) and were identified by gas chromatography-mass spectrometry-olfactometry (GC-MS-O) and gas chromatography-time-of-flight-mass spectrometry (GC-TOF-MS). A sensory evaluation of pea flour (PF) and PPI aqueous solutions was also conducted. From the instrumental analysis, 13 compounds were found to be likely the main contributors to the aroma profile of the samples examined. This hypothesis was also supported by the sensory data, which showed that the PF and PPI aqueous solutions were described with some of the odor descriptors used during the instrumental analysis. No new aroma compounds appear to be produced via the optimized pH-extraction and no existing compounds were completely removed from making a sensory contribution as determined by the olfactory analysis.

Evaluation of Physicochemical and Functional Properties of Isolated Pea Protein

Proteins were obtained from pea seeds. Protein solubility, water and oil absorption capacity, emulsifying capacity and emulsion stability, foaming capacity and foam stability were used to determine the pea a chemical and functional properties of protein. The pea protein, obtained by alkaline (NaOH 0.1 N) solubilization (pH 10) and 1:10 (gm/ml) ratio followed by TCA/Acetone precipitation, displayed the highest protein content and the best functional properties. The profiles of the solubility curves corresponding to the participated pea protein (PPP) indicate a minimum solubility at pH ranging from 4-10. The emulsifying capacity of pea participated pea protein was low (3.2) but it has high emulsifying stability (98.9). PPP show a high foaming capacity at pH2 and the suitable time to form the foam is 30 min. the high stability of foam was 78.8%. The result of this study emphasized that PPP has an ability to absorb water more than oil. Thus, the experimental suggesting that PPP can be successfully used as food ingredient due to its nutritional value, chemical composition and functional properties.

Spectrophotometric Determination of Fe(II) and Fe(III) Using 5-(4-Ethylphenyl azo ) 2-Hydroxybenzaldehyde Oxime Reagent

Spectrophotometric Determination of Fe(II) and Fe(III) Using 5-(4-Ethylphenyl azo ) 2-Hydroxybenzaldehyde Oxime Reagent

Multivariate optimization of a goat meat alkaline solubilization procedure using tetramethylammonium hydroxide for metals determination using FAAS

In the present work, multivariate designs were used to optimize an alkaline dissolution, assisted by ultrasound energy, procedure of goat meat using tetramethylammonium hydroxide (TMAH) aiming to determine Ca, Cu, Fe, K, Mg, Na and Zn by flame atomic absorption (FAAS) and emission (FAES) spectrometry. The optimal conditions found for the dissolution were in the following ranges: 0.4–0.5 g for the sample mass, 12–15 min of sonication and using 700–1000 µL of 25% TMAH at a temperature of 50 °C. The obtained limits of quantification varied between 0.221 (Mg) and 7.60 (Ca) μg g−1. Accuracy was assessed by comparing the results obtained by applying the proposed method with the digestion in an acid medium using a digesting block and by analyzing bovine liver certified reference material. The application of a t-test revealed that, at a 95% confidence level, there were no significant differences between the values obtained.