Protein Extraction Yield Research Articles

Composition and Techno-functional Properties of Grape Seed Flour Protein Extracts

Defatted grape seed flour (DGSF), a byproduct of the grape seed oil production, was investigated as a potential source of protein-enriched food ingredients with functional properties. The operation conditions of the alkaline extraction followed by the acid precipitation method were studied by response surface methodology, aiming to maximize the protein extraction yield. These conditions were temperature 50 °C, solvent/meal ratio 1:15, pH 11, and 150 min extraction time in two sequential extraction cycles, achieving a product with 32.63 ± 0.07% (w/w) d.m. of protein content. A second extract with 38.17 ± 1.34% (w/w) d.m. of protein was obtained under the same conditions, but using an additional centrifugation step before the acid precipitation. The amino acid profile, solubility, water and oil retention capacity, and emulsifying and foaming properties of the DGSF and the obtained extracts were compared. Both extracts could be used as food ingredients with different nutritional and technological purposes.

Melissa officinalis extracts obtained using maceration, ultrasoundand microwave-assisted extractions: Chemical composition, antioxidant capacity, and physical characteristics

Even though Melissa officinalis L. (lemon balm, fam. Lamiaceae) is a well-known medicinal, aromatic, and spicy plant, and its physicochemical profile and biological activity have been investigated, there is no detailed research regarding the influence of solvent nature (polarity) on the extraction of active compounds (total polyphenols and total flavonoids) and antioxidant activities of the obtained extracts. Therefore, this study aimed to evaluate the polyphenol and flavonoid contents, as well as the antioxidant potential of lemon balm extracts obtained by varying the polarity of the extraction solvents (methyl alcohol, acetone, ethyl acetate, and deionized water) and using three extraction techniques (maceration-MAC, ultrasound-UAE, and microwave-assisted extraction-MAE). Two in vitro tests (ABTS and FRAP assays) were used to determine the antioxidant activity of the extracts. Total tannin and total protein contents, extraction yield, and physical properties of the selected extracts were measured as well. The highest content of polyphenols was found for the methanolic and water extracts obtained by all three extraction techniques, while the highest flavonoid yield was detected only in the mentioned methanolic extracts. The microwave reactor provided methanolic, ethyl acetate, and water extracts with the highest ABTS radical scavenging activity, while in the case of UAE, it was methanolic and water extracts, and in the case of MAC only water extracts. On the other hand, among lemon balm extracts from MAC, water extract possessed the highest ferric reducing power, whereas in UAE and MAE, it was ethyl acetate extract. Total tannin content determined in selected water extracts was 2.55, 4.53, and 1.83 mg tannic acid equivalent (TAE)/mL, while total proteins amounted to 1.34, 1.50, and 1.31 mg/mL using MAC, UAE, and MAE, respectively. The content of total extractive substances in the form of the extraction yield was also determined for selected water extracts and amounted to 12.6 % for MAC, 17.2 % for UAE, and 36.8 % for MAE. Further, this research has included the investigation of some physical properties of lemon balm water extracts, such as conductivity (3.68-4.14 mS/cm), pH (5.99-6.43), density (0.854-0.901 g/mL), surface tension (26.0-31.7 mN/m), and viscosity (1.18-1.21 mPa·s). This research represents the base for the future encapsulation of lemon balm extracts, enriched in polyphenol content, in a novel type of biofunctional carrier that potentially can be applied in the pharmacy, chemical industry, and biotechnics.

Optimization of Microwave-Assisted Extraction of Palm Kernel Cake Protein

Palm kernel cake (PKC) is an abundant by-product of the palm oil industry. It is used as an ingredient in feed due to the high amount of protein and fiber content. In order to increase the value of PKC, the PKC protein can be extracted and may be able to be used as an alternative protein for plant-based food. This study aims to optimize the PKC protein extraction using the microwave-assisted extraction (MAE) method with a response surface methodology (RSM). MAE is a green extraction method due to less chemicals needed, less time and less energy consumption when compared to the traditional thermal extraction method. The experiment was designed by the Box-Behnken method with 3 factors; microwave power (A), extraction time (B) and solid-liquid ratio (C). The optimum condition was at the microwave power of 700.16 W, extraction time of 543.08 s and the solid-liquid ratio of 1:7.73 g PKC/ ml water resulting in a theoretical yield of protein extraction of 32.46%.

Protein extraction from cold-pressed hempseed press cake: From laboratory to pilot scale.

During the production of industrial hempseed oil, a press cake is formed as a byproduct, which is often used as animal feed although it contains a high amount of protein that could be used for human consumption. Extracting this valuable protein would reduce food waste and increase the availability of plant-based protein. A protein extraction process based on the pH-shift method was adapted to improve the protein extraction yield from industrial hempseed press cake (HPC). Parameters such as alkali extraction pH, time, and temperature, as well as isoelectric precipitation pH, were investigated in laboratory scale and were thereafter carried out in a pilot trial to explore the suitability for future scale up. The phytic acid content of the extracted protein isolate was also analyzed to investigate any potential inhibitory effect on mineral absorption. A final protein yield of 60.6%, with a precipitated protein content of 90.3% (dw), was obtained using a constant alkali extraction pH of 10.5 for 1 h at room temperature, followed by precipitation at pH 5.5. The pilot trial showed promising results for the future production of industrial hemp protein precipitate on a larger scale, showing a protein yield of 57.0% and protein content of 90.8% (dw). The amount of phytic acid in the protein isolate produced in the optimal laboratory experiment and in the pilot trial was 0.595 and 0.557g phytic acid/100g dw, respectively, which is 83%-88% less than in the HPC. This is in the range of other plant-based protein sources (tofu, kidney beans, peas, etc.). PRACTICAL APPLICATION: Industrial hempseed press cake is a byproduct in the production of industrial hempseed oil, which is mostly used as animal feed, but has the potential to become an additional source of plant-based protein for human consumption with a suitable protein extraction method. The extracted hemp protein could be used to develop new plant-based dairy or meat analog products.

Ultrasound-assisted alkaline proteinase extraction enhances the yield of pecan protein and modifies its functional properties

To enhance the extraction yield of pecan protein and modify its functional properties, this study investigated whether both ultrasound and enzyme have a synergistic impact on the extraction of pecan (Carya illinoinensis (Wangenh.) K. Koch) protein. The highest protein extraction rate (25.51%) was obtained under the conditions of 1415.43 W.cm−2, 15 min, pH 10.0, 50 °C, and 1% (w/w) alkaline proteinase. Owing to its high shear, mechanical energy and cavitation, the ultrasound process increased the solubility of the substrate making it readily accessible to the enzyme, thereby accelerating the chemical reaction and improving the yield of the protein. The optimized ultrasound-assisted enzymatic method (400 W, 20 kHz, 5 s/3s) effectively changed the secondary and tertiary structure of the pecan protein. The results of surface hydrophobicity, intrinsic fluorescence spectra, sulfhydryl content and scanning electron microscopy all indicated the unfolding of protein and exposure of hydrophobic groups and sulfhydryl groups. Moreover, the protein obtained by this method showed higher solubility (70.77%), higher emulsifying activity (120.56 m2/g), smaller particle size (326.7 nm), and better dispersion (0.305) than single ultrasound and non-ultrasound methods (p < 0.05). To conclude, ultrasound-assisted enzymatic method could be an appropriate technique to improve the yield and quality of the pecan protein. The study also provides a theoretical basis for the application of pecan protein in food processing.

Energy-efficient ultrasound-assisted extraction of food proteins from the microalga C. vulgaris at elevated static pressure

The microalga C. vulgaris is a potential source for sustainable food ingredients and particularly food protein. Ultrasonication can enhance the extraction of proteins from Chlorella, but a comprehensive comparison to other cell disintegration technologies is not possible since knowledge about the energy requirements is missing. In this article, the effects of an elevated static pressure up to 5 bar, sound amplitude, and treatment duration on energy consumption and protein extraction yield were explored. Elevating the static pressure affects the oscillation dynamics and collapses of cavitating bubbles and leads to more destructive collapses and higher energy. By employing numerical simulations of bubble oscillations, it was shown that the protein yield is mostly affected by the energy being radiated during the collapse of single bubbles and the total number of collapses during the treatment. Increasing the biomass concentration before sonication offers a way to further reduce the mass-specific energy input.

Properties of protein isolates extracted by ultrasonication from soybean residue (okara)

Soybean protein extraction was evaluated using conventional (alkaline phosphate buffer) and ultrasonication assisted methods. The impact of the extraction method on protein yield, chemical composition, and structural properties of the protein isolates was assessed. In conventional alkaline extraction, increasing pH values (from 9 to 12) led to an increase in the protein yield, with pH 12 favouring protein extraction, with yields up to 36 % (w/w). Ultrasonication process at the same pH, led to maximum protein extraction yield of 84 % (w/w). Secondary structural changes in ultrasonicated OPI samples were linked to cavitation effects and the duration of the extraction, rather than the intensity of ultrasonication process. Extracted proteins exhibited increased β-sheet content, improved zeta-potential and smaller particle size of ultrasonicated proteins, rendering them suitable ingredients for tailored food applications.

English

Ultrasound has been explored in recent times by researchers and food processing industries due to its capacity to increase extraction efficacy by enhancing mass transfer and rupturing cells due to acoustic cavitation. In protein extraction ultrasound treatment is generally used as a pretreatment in combination with the traditional method of extraction as it breaks the cell wall and improves the extractability. Ultrasound treatment not only improves the extraction rate but can also modify the functional properties of the protein product. The rate and yield of protein extraction depend on the operating conditions like power density of ultrasound, pulse, duration of ultrasonication, solid to solvent ratio, temperature, extraction solvent, pH, and so on. The current paper aims to present the impact of incorporating ultrasound technology with traditional technologies on the yield and functional properties of protein extraction from plant sources.

Protein Extractability and Thermally Induced Gelation Properties of African Locust Bean Proteins (Parkia biglobosa Jacq. R.Br)

African locust bean (AfLB) protein isolates could be an interesting alternative to the use of soy as an ingredient for the development of new protein-rich products. From AfLB seed flour, the protein extractability yields by aqueous extraction were determined as a function of pH and ionic strength. Then thermally induced gelation of various protein suspensions relating to protein concentration was studied. The most critical factors affecting extractability were the pH and the presence of fat. As a function of the extraction process, the extraction yield of protein from AfLB flour ranged from 30 to 65%. Two major fractions of proteins detected in AfLB seeds were albumins and globulins, comprising four families: legume-like protein, vicilin-like proteins, convicilin, and albumins. The globulin isolate had the lowest solubility at pH 3.5-4 and the highest at pH 8-10. The solubility of albumin isolate was lightly affected by pH and ionic strength. At pH 7, the minimum protein concentration for thermal gel formation ranged from 55 to 120 g/L as function purified state of proteins. The less purified extract with a simpler process made it possible to obtain a gel needing a lower protein concentration. This last way seems promising to the development of new foods based on African locust bean flour.

Valorisation of Brewer’s Spent Yeasts’ Hydrolysates as High-Value Bioactive Molecules

Brewer’s spent yeast (BSY) is produced by the beer industry and has high nutritional value and great potential for producing high-value molecules, such as peptides, for nutraceutical, food and feed applications. In the present research, Flavourzyme® and Protamex® enzymes were selected for protein hydrolysis based on previous studies. The optimum conditions for the enzymatic hydrolysis were defined by response surface methodology (RSM) by the Box–Behnken design composed of four variables: temperature, pH, enzyme dosage and time. Protein content, hydrolysis degree and the anti-microbial and antioxidant bioactivities of obtained hydrolysates were quantified. Obtained results show that time, enzyme dosage and pH had the highest effect on protein extraction yield (PEY), degree of hydrolysis (DH) and antioxidant activity. Response variables ranged from 13.7 to 29.7% for PEY, from 6.3 to 35.7% for DH and from 0.65 to 1.65 g for Trolox equivalent antioxidant capacity. Antimicrobial activity, measured as minimum inhibitory concentration, against Aeromonas salmonicida, Bacillus cereus, Bacillus subtilis and Salmonella enterica, ranged from 6.25 to 50 mg/mL. Antioxidant and antimicrobial activity showed the potential use of BSY hydrolysates as an ingredient for functional foods.

High‐power sonication‐assisted extraction of soy protein from defatted soy meals: Influence of important process parameters

AbstractThis study investigated the influence of important process parameters in high‐power sonication (HPS)‐assisted alkali extraction of protein from defatted soybean flakes and flour for higher yields. HPS power densities from 90 to 720 J/mL, substrate: water ratios at 1:8, 1:10, and 1:12 (wt/vol), and extraction durations of 15‐ and 30‐min were evaluated for their impact on protein recovery from meals. Extraction was carried out at 60°C and pH 8.5, and the protein content of the supernatant was determined with bicinchoninic acid assay (BCA) assay. Flakes showed the highest protein recovery of 77.5% at 720 J/mL and 15 min extraction with an unsonicated control of 63.0%. Being smaller in particle size, flour was less susceptible to HPS treatments and showed the highest protein recovery of 80.3% at 360 J/mL and 30 min extraction with an unsonicated control of 74.3%. HPS recovered a comparable amount of protein from flakes compared to recovery from sonicated or unsonicated flours. In addition, HPS treatments resulted in shorter incubation durations and generated higher yields without further extraction at 60°C. Thus, it decreased the yield difference between incubation durations and decreased cumulative protein release rate. HPS reduced the volume‐weighted mean diameter (D[4,3]) of flakes by more than fourfold; however, it did not significantly reduce the flour size further. It can thus be summarized that HPS pretreatment breaks the cellular structure of soybean meals, mostly flakes, and can significantly increase the protein recovery from them, even when extraction times are shortened.Practical ApplicationsApplication of high‐power sonication (HPS) technology was shown to increase protein extraction yields by 10‐15% beyond conventional alkali extraction from soymeal by reducing the particle size of the meal. Conventional alkali extraction utilizes soy flour and requires 30 min incubation at 60ºC, whereas HPS pretreatment increased protein extraction yield in less incubation duration andless amount of water in the substrate based on the types of substrate. Therefore, HPS could improve protein yield and reduce the cost of production by reducing incubation duration, saving energy, and utilizing flakes instead of flourduring conventional industry scale processing.

Ion Exchange Fraction of Fish by-Products Protein as a Food Protein Fortification Ingredient

Stunting is one of the nutritional problems in developing countries, and finding alternative affordable protein source to overcome the problem remains challenging. Protein fortification or enrichment is one of the options in the development of high-quality food protein. The by-product of the food industry, such as the fish industry, that still rich in protein could be targeted as protein to be used in fortification. Mackerel fish by-products were extracted using acid (pH 2.5), base (pH 12.0), and surfactant (SDS 0.01%), then the protein was fractionated using the cationic exchange-solid phase extraction (SPE-SCX). The yield of protein extraction using HCl (pH 2.5), NaOH (pH 13) and SDS 0.01% are 32.55, 5.50, and 20.40%, respectively. Analysis of protein SCX fraction found that fraction pH 6 and 7 of HCl protein extract and pH 5, 7, and 8 of SDS protein extract meet criteria as protein fortificants. Those fractions met the minimum required content of essential amino acid as well as the chemical score of each essential amino acid. The extraction process determines the outcome of fractionation, with SDS extraction gives a better result.

Protein extraction yield, lipid composition, and emulsifying properties of aqueous extracts of Rhynchophorus phoenicis larvae extracted at pH 3.0 to 10.0.

Aqueous extracts of Rhynchophorus phoenicis larvae were prepared at pHs 3.0 to 10.0 to screen their macronutrient composition, emulsifying properties and identify the best conditions to extract a functional protein ingredient. The results showed that the aqueous extracts contained both proteins (0.85 – 4.62 mg/mL), characterized by a large range of molecular weights, and lipids (0.28 to 1.54 mg/mL). The lipids were composed mainly of triacylglycerols (0.21 to 0.95 mg/mL) and free fatty acids (FFA, 0.06 to 0.62 mg/mL) with the highest FFA levels at alkaline pHs; they contained 4.1 to 8.8 g polyunsaturated fatty acids per 100 g total fatty acids. The highest protein extraction yield (54%) of the insect proteins occurred at pH 9.0–10.0. Whatever the extracting pH, the aqueous extracts were able to stabilize oil-in-water emulsions. The emulsions prepared with the pH 9.0 and 10.0 aqueous extracts had however the lowest mean droplet size (d4.3 < 2 µm), and showed no creaming after storage at 4 °C for one weak, indicating that stable emulsions can be prepared at these pHs. Alkaline conditions of extraction will thus be suitable to prepare protein concentrate/isolate of R. phoenicis larvae and test their aptitude to be used to formulate new food products.

Improved backward extraction of walnut protein using AOT reverse micelles with microwave and its characteristics

The extraction of walnut protein (WP) was carried out using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles with microwave-assisted backward extraction (MABE), which was potential to improve the extraction yield of WP. And the functional and structural properties were determined. The optimized conditions by response surface methodology were extraction time 30 min, extraction temperature 45°C, and aqueous solution to forward extraction solution ratio 3:1 (vol/vol), the backward extraction yield reached 95.43 ± 2.08%. WP from MABE exhibited the higher solubility (68.35 ± 0.67%), oil absorption capacity (2.43 ± 0.21 g/ml), water holding capacity (2.78 ± 0.02 g/ml), foam capacity (64.03 ± 1.20%), foam stability (72.17 ± 3.05%), emulsifying activity index (3.24 ± 0.86 m2/g), and emulsifying stability index (70.20 ± 0.21 min). FTIR revealed that the main backbone structure changes of WP after microwave treatment did not occur, there was a small change of protein structure, with the increase of α-helix and random coil proportions, decrease of β-turn and similar β-sheet content. Practical applications A novel microwave-assisted backward extraction method of reverse micelle was developed. The backward extraction yield and functionality of walnut protein (WP) with this method could be improved. This work have the potential for promoting the application of reverse micelles in the food industry.

Production of Coconut Oil and Protein for Food and Cosmetic Ingredients

Coconut (Cocos nucifera) is a tropical plant that is almost spread throughout the archipelago. Coconut is a plant of the genus Cocos widely used in various fields ranging from food to cosmetics. Most coconut parts can be utilized so that the coconut is dubbed a versatile plant and has high economic value. This tree has a fruit which is also called coconut. Coconut fruit is the most widely used and processed. Coconut meat can be directly consumed or processed into coconut milk, coconut flour (desiccated coconut), and cooking oil. Coconut oil was obtained from dried or fresh coconut flour using the Soxhlet extraction method with organic solvents. Defatted coconut flour contained a high protein of approx. 19-20%. Coconut protein has a good quality compared to other vegetable protein sources. This research investigated solvent’s effect on solid ratio and oil content on coconut protein extraction yield and recovery from coconut flour. Based on experiments, the highest value of extracted protein and yield was obtained after coconut flour extraction at a solvent to flour ratio of 30 g/g. Coconut protein isolate and coconut whey protein were expected to have different functional properties which need to be further evaluated to determine their application as cosmetics or food ingredients.

Effects of the intensification of soybean defects: consequences on the physicochemical, technological, protein and oil properties

The objective of this study was to evaluate the physicochemical and technological properties of flour, oil and protein isolate from defective soybean seeds. The seeds were classified as not defective, partially fermented, completely fermented, and burned soybeans. The intensification of defects promoted increases of 10.85, 2248.89 and 2031.98%, respectively, for ash, acidity, and oil lipase activity, and reductions of 11.25, 98.51 and 59.10%, respectively, for lipid content, protein extraction yield and protein solubility of the protein isolate, when compared to not defective soybeans. Increases in daidzein, genistein, and glycitein isoforms content were observed in the protein isolate from defective soybeans when compared to not defective soybean protein isolate. The flour, oil, and protein isolate obtained from defective seeds presented undesirable alterations for food industries. The utilization of defective soybeans will reduce the quality and yield of soybean processing when destined for oil and protein extraction.

Process development of enzymatically-generated algal protein hydrolysates for specialty food applications

Lipid-extracted microalgae is a cheaper feedstock alternative to whole cell microalgae for production of protein products. Pre-extraction of high-value lipids significantly reduces biomass costs and concentrates protein in the de-lipidated biomass residue. Protein hydrolysates are one of the most valuable products that could be obtained from lipid-extracted microalgae. Their high solubility makes them particularly suited as supplements in high-value sport and nutritional drinks. Additional advantages of protein hydrolysates over other protein products include enhanced digestibility and potential bioactivity. Still, the development of feasible downstream processes for the economic production of hydrolysates from lipid-extracted microalgae is at an exploratory stage. Previous work has studied the protein hydrolysis reaction but major processing factors such as extraction yield, protein purity, and appearance of the final product are yet to be optimized. This study aimed to develop a process for the production, recovery, and purification of protein hydrolysates from lipid-extracted microalgae. Results showed that mechanical lysis of the lipid-extracted microalgae was necessary to maximize the protein hydrolysis rate and extraction yield. Once hydrolyzed and released, a combination of acidic precipitation, centrifugation, and depth filtration, followed by an ion exchange step for salt removal, yielded a final protein recovery and purity of 64 and 72%, respectively. To our knowledge, this is the first study reporting such high purity and recovery for an algae protein product. The hydrolysate produced was free of chlorophyll and consisted mostly of 1–20 kDa peptides with an amino acid distribution comparable to that of soy protein.

Effects of ultrasonic pre-treatment on physicochemical properties of proteins extracted from cold-pressed sesame cake

Sesame is an oil crop with high nutritional value. Protein is one of the main ingredients of sesame, however research on protein of cold-pressed sesame cake is limited. This study aimed to investigate the effects of ultrasonic pre-treatment (UPT) on physicochemical properties of proteins (yield, solubility, amino acid composition, surface properties, structural and thermal stability) extracted from the cold-pressed sesame cake, after removing lignans by ultrasonic-assisted extraction. By comparison, the extraction yield of protein was significantly (p ＜ 0.05) increased from 22.24% (without UPT) to 25.95% (with UPT), while the purity (54.08% without UPT, 55.43% with UPT), total amount of essential amino acids (22.48% without UPT, 23.10% with UPT) and non-essential amino acids (37.48% without UPT, 36.54% with UPT) were not significantly influenced. Besides, UPT slightly reduced the solubility, foaming capacity and stability (FC and FS) of protein. In addition, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and thermal stability (TG) analysis demonstrated that UPT could disorder and loose protein molecular structure, resulting in the change of morphology, secondary structure and thermal stability. In conclusion, this study provides a way for the separation and future application of sesame cake protein. UPT is a good option to remove the lignans from sesame cake proteins.

Reverse microemulsion prepared by AOT/CTAB/SDS/Tween80 for extraction of tea residues protein

The work attempted to study a new method for tea residue protein extraction. In this study, three kinds of microemulsion systems were constructed and their phase behaviors were investigated and compared. The conductivity, viscosity, surface tension and particle size were used to characterize the reverse microemulsion. Then, three kinds of microemulsion systems were used to extract tea residues protein. Based on the results of tea residues protein extraction yield with orthogonal optimization, CTAB-Tween80 microemulsion was more robust to extract protein, and the tea residues protein extraction yield could reach 42.1%. This study indicated that the CTAB-Tween80 reverse microemulsion has the potential ability to extract the tea residue protein.

Characterization and Demulsification of the Oil-Rich Emulsion from the Aqueous Extraction Process of Almond Flour

The aqueous extraction process (AEP) allows the concurrent extraction of oil and protein from almond flour without the use of harsh solvents. However, the majority of the oil extracted in the AEP is present in an emulsion that needs to be demulsified for subsequent industrial utilization. The effects of scaling-up the AEP of almond flour from 0.7 to 7 L and the efficiency of enzymatic and chemical approaches to demulsify the cream were evaluated. The AEP was carried out at pH 9.0, solids-to-liquid ratio of 1:10, and constant stirring of 120 rpm at 50 °C. Oil extraction yields of 61.9% and protein extraction yields of 66.6% were achieved. At optimum conditions, enzymatic and chemical demulsification strategies led to a sevenfold increase (from 8 to 66%) in the oil recovery compared with the control. However, enzymatic demulsification resulted in significant changes in the physicochemical properties of the cream protein and faster demulsification (29% reduction in the incubation time and a small reduction in the demulsification temperature from 55 to 50 °C) compared with the chemical approach. Reduced cream stability after enzymatic demulsification could be attributed to the hydrolysis of the amandin α-unit and reduced protein hydrophobicity. Moreover, the fatty acid composition of the AEP oil obtained from both demulsification strategies was similar to the hexane extracted oil.