Oil-in-water emulsions stabilized by tyrosinase-crosslinked potato protein

Modification approaches of walnut proteins to improve their structural and functional properties: A review

Walnut protein has a high gluten content and compact structure, which limits its water solubility and affects its applications. Therefore, improving the sustainability of walnut proteins is an urgent issue that must be addressed. Physical modification can directly alter the structure of walnut proteins, leading to enhanced functional properties. Chemical modifications typically involve the introduction of exogenous substances that react with walnut proteins to obtain novel products with improved processing attributes. As a highly specific modification technique, biomodification uses enzymes or microorganisms to break down walnut proteins into small peptide molecules or cross-link them to form soluble polymers, thereby enhancing their functional properties and bioactivity. This review presents various methods for modifying walnut proteins and their effects on the structure and functional properties of walnut proteins. The challenges associated with the application and development of these unique technologies are also discussed.

Interfacial and Bulk Properties of Potato and Faba Protein in Connection with Physical Emulsion Stability at Various pH Values and High Salt Concentrations

The protein transition motivates the use of plant proteins, but their application in food emulsions is challenging, especially when high concentrations of oil and salt are needed for formulation and sensory properties. In the present work, we connect the iso-electric point of two potato protein isolates (patatin-rich, POPI-200; protease inhibitor-rich, POPI-300) and a faba protein isolate (FPI) to the behavior in the bulk phase and at the interface, and relate this to the physical stability of 45 wt% oil-in-water (O/W) emulsions in the presence of NaCl at pH 4.0-7.0. In the absence of NaCl, a higher bulk viscosity was found at the iso-electric point (IEP), especially for the FPI. In the presence of NaCl, the viscosity of the POPI-200 solutions was highest, followed by POPI-300, and that of the FPI was lowest, irrespective of the pH. Both POPIs showed faster initial adsorption at the O/W interface in the absence of NaCl, and formed a more elastic layer compared to the FPI. For all proteins, salt addition leads to less elastic films. Interestingly, the interfaces were more elastic at a pH close to the IEP of the protein in the presence of NaCl. Both POPI-stabilized emulsions showed higher stability (smaller size and less oiling off) than the FPI-stabilized emulsions, which makes potato proteins relevant for food emulsion product formulation, even under high salt conditions.

Progress in using cross-linking technologies to increase the thermal stability of colloidal delivery systems

In recent years, crosslinking technology has been found and widely used in food, textile, pharmaceutical, bioengineering and other fields. Crosslinking is a reaction in which two or more molecules bond to each other to form a stable three-dimensional network structure to improve the strength, heat resistance and other properties of substances. The researchers found that the cross-linking technology has a significant effect on improving the thermal stability of the colloidal delivery system. In this paper, crosslinking techniques that can be used to improve the thermal stability of colloidal delivery systems are reviewed, including enzyme-, ion-, chemical-, and combined cross-linking. Initially, the underlying mechanisms of these crosslinking technologies is reviewed. Then, the impacts of crosslinking on the heat-stability of colloidal delivery systems are discussed. Finally, the application of crosslinked delivery systems in improving the thermal stability of probiotics, polyphenols, pigments, and nutrients in foods and food packaging materials is introduced. The ability of proteins and polysaccharides to form heat-stable colloidal delivery systems can be improved by crosslinking. Nevertheless, more research is required to establish the impact of different crosslinking on the thermal stability of a broader range of different delivery systems, as well as to ensure their safety and efficacy.

Physical, Chemical and Biochemical Modification Approaches of Potato (Peel) Constituents for Bio-Based Food Packaging Concepts: A Review

Potatoes are grown in large quantities and are mainly used as food or animal feed. Potato processing generates a large amount of side streams, which are currently low value by-products of the potato processing industry. The utilization of the potato peel side stream and other potato residues is also becoming increasingly important from a sustainability point of view. Individual constituents of potato peel or complete potato tubers can for instance be used for application in other products such as bio-based food packaging. Prior using constituents for specific applications, their properties and characteristics need to be known and understood. This article extensively reviews the scientific literature about physical, chemical, and biochemical modification of potato constituents. Besides short explanations about the modification techniques, extensive summaries of the results from scientific articles are outlined focusing on the main constituents of potatoes, namely potato starch and potato protein. The effects of the different modification techniques are qualitatively interpreted in tables to obtain a condensed overview about the influence of different modification techniques on the potato constituents. Overall, this article provides an up-to-date and comprehensive overview of the possibilities and implications of modifying potato components for potential further valorization in, e.g., bio-based food packaging.

Yeast-derived potato patatins: Biochemical and biophysical characterization

Potato patatin is considered a valuable plant protein by the food industry for its exceptional functional properties and nutritional value. Nonetheless, it has not been widely used due to its low abundance in potatoes and high cost. Pichia pastoris was utilized for expression of patatin to overcome agricultural limitations. Biochemical and biophysical characterization of Patatin-B2 (rPatB2) and Patatin-17 (rPat17) is described. rPatB2 and rPat17 had higher zeta potential and superior solubility at various pH conditions in comparison with commercial patatin, whereas particle size distribution was similar. Inflection temperatures were higher than potato isolated patatins. Antioxidant capacity of rPatB2 and rPat17 was similar to that of commercial patatin and the specific enzymatic activity of rPatB2 was 5-fold higher than rPat17 and patatins isolated from potato. Results indicate yeast-derived patatin properties are comparable to patatins from potatoes, suggesting their potential use in various plant-based products such as meat and dairy analogues.

Potato protein: current review of structure, technological properties, and potential application on spray drying microencapsulation

Studies regarding spray drying microencapsulation are aplenty available; especially focusing on processing parameters, microparticle characteristics and encapsulation efficiency. Hence, there is a rising interest in tailoring wall materials aiming to improve the process's effectiveness. Reflecting a market trend in the food industry, plant-based proteins are emerging as alternative protein sources, and their application adaptability is an increasing research of interest related to consumers' demand for healthy food, product innovation, and sustainability. This review presents a perspective on the investigation of potato protein as a technological ingredient, considering it a nonconventional source obtained as by-product from starch industry. Furthermore, this piece emphasizes the potential application of potato protein as wall material in spray drying encapsulation, considering that this purpose is still limited for this ingredient. The literature reports that vegetal-based proteins might present compromised functionality due to processing conditions, impairing its technological application. Structural modification can offer a potential approach to modify potato protein configuration aiming to improve its utilization. Studies reported that modified proteins can perform as better emulsifiers and antioxidant agents compared to intact proteins. Hence, it is expected that their use in microencapsulation would improve process efficiency and protection of the core material, consequently delivering superior encapsulation performance.

Analysis of protein-network formation of different vegetable proteins during emulsification to produce solid fat substitutes

Plant-based emulsion gels can be used as solid animal fat substitutes for vegan sausages. For this reason, commercially available protein isolates with different amino acid profiles from pea, soy and potato (Pea-1, Pea-2, Soy, Potato) have been tested for their ability to form shape stable emulsions gels at neutral pH and upon heating to 72 °C. In order to obtain emulsion gels that are as solid as possible, the protein concentrations in the continuous phase (CPC, 8.0–11.5% (w/w)) and the oil mass fractions (65–80%) were varied. For leguminous proteins, a positive correlation of both parameters on emulsion rigidity was shown, indicating that both, interfacial and protein–protein interactions, are involved in structure reinforcement. Firmness increased with increasing content in cysteine (Pea-1 < Pea-2 < Soy) and the interactions were of electrostatic, hydrophobic and hydrophilic nature. Potato emulsion rigidity was independent of CPC and oil content. The emulsions showed a much higher degree in crosslinking, and very low charge density. Temperature-sweep analysis and CLSM revealed that Potato protein gelled as consequence to low temperature stability. Hence, the structure reinforcement in Potato emulsions mainly contributed to the protein network, with 70% oil and CPC 11.5% forming a hybrid gel with highest firmness. However, gelling of Potato protein also resulted in interfacial adsorption of protein aggregates and reduced interfacial stability with increasing CPC. This was demonstrated in the amount of extractable fat which was 2.0 and 0.6% for Pea-1 and 2 emulsions, 6.4% for Soy and 34.4% of total fat for Potato emulsions.

Physicochemical properties and digestive kinetics of whey protein gels filled with potato and whey protein mixture emulsified oil droplets: effect of protein ratios

Incorporating protein emulsified droplets into protein gels as active fillers have attracted much attention. However, using animal and plant protein mixtures emulsified droplets as the filler is lacking. We investigated the effect of emulsified droplets covered by potato protein (PP) and whey protein (WP) mixtures of different ratios (10/0, 9/1, 7/3, 5/5, 3/7, 1/9, 0/10) on mechanical, microstructural characteristics and digestion of emulsion-filled WP gels (EFWG). The results showed that the particle size of emulsified droplets increased with the enhancement of PP ratio, whereas their ζ-potential value decreased. Increasing the PP ratio improved the elastic moduli (G'), fracture stress and hardness of EFWG, while lowered the water holding capacity and swelling ratios of EFWG. Confocal laser scanning microscopy revealed that a higher PP ratio leads to a thicker gel skeleton and fine network. Although the enhancement of the PP ratio decreased disulfide bond content in EFWG, it improved the hydrogen bond and total non-covalent interactions in EFWG. Increased PP in filling emulsions delayed the release rate of the free amino group and free fatty acid during digestion. Moreover, the presence of NaCl improved the gel properties and digestion of EFWG. The findings of this study may provide information for developing new WP gel products with specific digestion rates.

Laccase-catalyzed conjugation of potato protein (PPT) with selected pectic polysaccharides (PPS): Conjugation efficiency and emulsification properties

The current study focused on the investigation of laccase-catalyzed conjugation of potato protein (PPT) with selected pectic polysaccharides (PPS) and modulation of the conjugation in order to obtain desired functional ingredients. PPS, including sugar beet pectin/arabinan, apple/citrus pectin and potato galactan, were evaluated as substrates in the conjugation reaction-catalyzed by laccases (Trametes versicolor-LacTv, Coriolus hirsutus-LacCh). LacCh exhibited a higher catalytic efficiency than LacTv. The reactivity of PPT/PPS and their ratio were determinants for their heteroconjugation. Both laccases exhibited the highest specificity towards the conjugation of PPT/sugar beet pectin. Predictive models were developed for conjugation efficiency and emulsification performance. The conjugation extent was negatively affected by the protein proportion and the protein proportion/enzyme concentration interaction; while the emulsification performance was positively correlated with the protein proportion and the protein proportion/reaction time interaction. This study contributed to the understanding of laccase-catalyzed conjugation reaction for the controlled synthesis of conjugated-PTT as functional ingredients.

The functionality of laccase- or peroxidase-treated potato flour: Role of interactions between protein and protein/starch

Potato flour is used in bakery products, extruded products and snacks. However, it displays weaker gel strengths and thus the wholesome utility is curtailed significantly. To improve viscoelastic properties and stability of potato gels, herein potato flour was treated with laccase and peroxidase to create a protein network structure leading to stable gels. The results revealed that the secondary structure of potato proteins altered upon the enzyme treatment. The gels of peroxidase-treated potato flour (PPF) and laccase-treated potato flour (LPF) displayed larger anti-shear ability, thermal stability and stronger three-dimensional network structure compared to the native potato gel. The PPF and LPF gels exhibited stronger viscoelastic properties and structural stability compared to peroxidase-treated potato protein and laccase-treated potato protein gels. The outcome serves as a theoretical basis to improve the properties of potato gels and to promote the designing and the development of novel potato flour based functional food.

Solubility and emulsifying activity of yam soluble protein

Yam soluble protein (YSP) has been reported to have many physiological activities, such as scavenging free radicals, immune activation, and anti-hypertensive activities. Protein solubility and emulsifying activity are important protein-associated functional properties for the application of proteins in food systems. During this study, the factors of protein concentration, pH, temperature and salt concentration that influenced the solubility of YSP were investigated. As a result, the solubility was minimal near its isoelectric point (pH 3.5) and was highest at 45 °C in a temperature range of 40-60 °C. With an increase of protein concentration, the solubility decreased. According to the results of response surface methodology analysis, the interaction between pH and temperature on the solubility of YSP was significant, and the maximum solubility (87.5%) was obtained when the temperature was close to 40 °C, the pH was approximately 7 and the NaCl concentration approached 0.5 mol/L. As the protein concentration increased, the average particle size of the YSP emulsion decreased, and the particle size distribution gradually became balanced. Additionally, the microphotograph of the YSP emulsion reflected its distribution. The results of this study will provide data and a theoretical basis for the understanding of YSP's physicochemical properties and its application in the food industry.

Preparation and characterization of potato protein-based microcapsules with an emphasis on the mechanism of interaction among the main components

BACKGROUND

Potato protein (PP) has promising potential for utilization in food applications due to its high nutritive value and functional properties. Grapeseed oil (GO) is rich in unsaturated fatty acids and antioxidant active ingredients. However, its application is limited because of low stability and high volatility. In order to overcome such problems, PP-based microcapsules encapsulating GO were produced by complex coacervation, and characterized using optical, thermodynamic and spectroscopic analyses.

RESULTS

Results indicated that a ratio of GO/PP of 1:2 led to the best encapsulation effect with the maximum microencapsulation efficiency and yield. Intact and nearly spherical microcapsules were observed from scanning electron microscopy images. Results of thermogravimetry demonstrated that thermal resistance was increased in the microencapsulated GO, indicating that PP-based microcapsules could be a good way to protect the thermal stability of GO. Fourier transform infrared spectra indicated that hydrogen bonding and covalent crosslinking might occur among wall materials, but a physical interaction between GO and wall materials.

CONCLUSIONS

PP can be successfully used to encapsulate GO when combined with chitosan, indicating that PP-based microcapsules have potential for application in encapsulating liquid oils with functional properties. A schematic diagram of possible interactions was constructed to better understand the mechanism of formation of the microcapsules. © 2020 Society of Chemical Industry.

Tyrosinase-crosslinked pea protein emulsions: Impact of zein incorporation

The effect of tyrosinase-crosslinking of pea protein and pea-zein complexes on the properties of concentrated o/w emulsions was studied in the present work. Emulsions comprising 2% pea protein (w/w) solubilized in the aqueous phase (60% w/w) with or without zein solubilized in the oil phase (40% w/v), were fabricated by using high pressure homogenization. Tyrosinase treated emulsions (TyrBm-crosslinked) and non-crosslinked emulsions were evaluated after 2 h of incubation. Crosslinked pea protein stabilized emulsions led to better stability, larger particle size, increased viscosity and a paste-like structure, compared to non-crosslinked pea protein stabilized emulsions. Zein incorporation in the crosslinked pea-zein stabilized emulsions, contributed to significant improvement of stability and an increase in G' concurrently with a gel-like structure formation (G' > G″), compared to the non-crosslinked pea-zein and crosslinked pea protein stabilized emulsions. In general, crosslinked emulsions showed higher protein adsorption percentage compared to non-crosslinked emulsions, while the fraction adsorbed at the oil/water interface contained crosslinked convicilin/vicilin and zein fractions. Altogether, results demonstrate that enzymatic covalent bond formation in pea protein or zein-pea protein complexes is a useful approach to design and formulate sauces, cheese and meat replacements, and other vegetarian or vegan emulsion based foods. In addition, this work represents a step forward in application of functionalized zein in concentrated oil-in-water-emulsions.