Impact of legume protein type and location on lipid oxidation in fish oil-in-water emulsions: Lentil, pea, and faba bean proteins

Comparative Study of Oxidative Structural Modifications of Unadsorbed and Adsorbed Proteins in Whey Protein Isolate-Stabilized Oil-in-Water Emulsions under the Stress of Primary and Secondary Lipid Oxidation Products

The impact of typical primary or secondary lipid oxidation (LPO) products, selected as linoleic acid 13-hydroperoxide (13-HPODE) and malondialdehyde (MDA), on the structural modification of unadsorbed or adsorbed proteins in whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions during storage up to 48 h at 37 °C in the dark was investigated. The results showed that either 13-HPODE and MDA could lead to structural modifications of unadsorbed or adsorbed proteins with a concentration-dependent manner and time relationship, respectively. Moreover, higher levels of MDA rendered a higher degree of oxidative modifications of WPI than 13-HPODE, indicated by the higher protein carbonyl contents and N'-formyl-L-kynurenine (NFK) and lower fluorescence intensity. Additionally, adsorbed proteins were more easily oxidized by LPO products than unadsorbed proteins. Overall, our results indicated that the formation of secondary LPO products and the protein position were crucial factors to increase the degree of oxidative modifications of WPI in O/W emulsion systems.

Effect of sesamol on the physical and chemical stability of plant-based flaxseed oil-in-water emulsions stabilized by proteins or phospholipids

Plant-based polyphenols are increasingly being explored as functional ingredients in emulsified food systems. In this study, the effects of sesamol on the physical and chemical stability of flaxseed oil-in-water emulsions stabilized by either phospholipids (sunflower) or proteins (whey or pea) were investigated. In the absence of sesamol, the protein-based emulsions displayed better physical stability than the phospholipid-based ones, which was related to their smaller particle diameter and higher particle charge. For the phospholipid-based emulsions, sesamol addition did not improve their physical stability, but it did inhibit lipid oxidation. In particular, it decreased the formation of secondary oxidation products, with a 65% reduction in TBAR formation compared to the control after 8 days of storage. For the protein-based emulsions, sesamol addition reduced particle aggregation and inhibited lipid oxidation, reducing the secondary oxidation products by around 85% after 19 days of storage. The inhibitory efficiency of sesamol in the pea protein-based emulsions was comparable to that in the whey protein-based ones. The effects of sesamol on the physical and chemical stability of the emulsions were related to its partitioning between the oil, water, and interfacial layers. This study suggests that adding sesamol to plant-based emulsions may improve their physical and chemical stability, thereby extending their shelf life.

Fabrication and characterization of anchovy protein hydrolysates-polyphenol conjugates with stabilizing effects on fish oil emulsion

Conjugation between peptides and polyphenols could improve their bioactive and functional properties. The improvement effects of anchovy protein hydrolysates (APH) -polyphenol (catechin (CA), gallic acid (GA), tannic acid (TA)) conjugates were investigated. The content of protein and polyphenols and ratio of polyphenols/peptides in conjugates increased as the number of OH group increased with TA > CA > GA. Results showed that APH-CA and APH-GA exhibited the highest ORAC and ABTS⁺ scavenging capacity, respectively. Mass spectrometry analysis suggested the highest number of bioactive peptides were identified in APH-CA 5:1 (APH/polyphenols). The physical stability of fish oil emulsions during storage was significantly enhanced by TA 5:1 conjugate followed by CA 5:1 conjugate. The oxidative stability was remarkably elevated by APH-GA 10:1. This was due to the antioxidant capacity and the peptides adsorbed at the interfacial. This study demonstrated that APH-polyphenol conjugates could bring the possibility of utilizing peptides-polyphenols in the nutraceutical and functional food ingredient fields.

Proteins from leguminous plants: from structure, property to the function in encapsulation/binding and delivery of bioactive compounds

Leguminous proteins are important nutritional components in leguminous plants, and they have different structures and functions depending on their sources. Due to their specific structures and physicochemical properties, leguminous proteins have received much attention in food and nutritional applications, and they can be applied as various carriers for binding/encapsulation and delivery of food bioactive compounds. In this review, we systematically summarize the different structures and functional properties of several leguminous proteins which can be classified as ferritin, trypsin inhibitor, β-conglycinin, glycinin, and various leguminous proteins isolates. Moreover, we review the development of leguminous proteins as carriers of food bioactive compounds, and emphasize the functions of leguminous protein-based binding/encapsulation and delivery in overcoming the low bioavailability, instability and low absorption efficiency of food bioactive compounds. The limitations and challenges of the utilization of leguminous proteins as carriers of food bioactive compounds are also discussed. Possible approaches to resolve the limitations of applying leguminous proteins such as instability of proteins and poor absorption of bioactive compounds are recommended.

Standardized methods for testing the quality attributes of plant-based foods: Milk and cream alternatives

The food industry is creating a diverse range of plant-based alternatives to dairy products, such as milks, creams, yogurts, and cheeses due to the increasing demand from consumers for more sustainable, healthy, and ethical products. These dairy alternatives are often designed to mimic the desirable physicochemical, functional, and sensory properties of real dairy products, such as their appearance, texture, mouthfeel, flavor, and shelf-life. At present, there is a lack of systematic testing methods to characterize the properties of plant-based dairy alternatives. The purpose of this review is to critically evaluate existing methods and recommend a series of standardized tests that could be used to quantify the properties of fluid plant-based milk alternatives (milk and cream). These methods could then be used to facilitate the design of milk alternatives with somewhat similar attributes as real dairy milk by comparing their properties under standardized conditions. Moreover, they could be used to facilitate comparison of the properties of milk alternatives developed in different laboratories.

Legume proteins are smart carriers to encapsulate hydrophilic and hydrophobic bioactive compounds and probiotic bacteria: A review

Encapsulation is a promising technological process enabling the protection of bioactive compounds against harsh storage, processing, and gastrointestinal tract (GIT) conditions. Legume proteins (LPs) are unique carriers that can efficiently encapsulate these unstable and highly reactive ingredients. Stable LPs-based microcapsules loaded with active ingredients can thus develop to be embedded into processed functional foods. The recent advances in micro- and nanoencapsulation process of an extensive span of bioactive health-promoting probiotics and chemical compounds such as marine and plant fatty acid-rich oils, carotenoid pigments, vitamins, flavors, essential oils, phenolic and anthocyanin-rich extracts, iron, and phytase by LPs as single wall materials were highlighted. A technical summary of the use of single LP-based carriers in designing innovative delivery systems for natural bioactive molecules and probiotics was made. The encapsulation mechanisms, encapsulation efficiency, physicochemical and thermal stability, as well as the release and absorption behavior of bioactives were comprehensively discussed. Protein isolates and concentrates of soy and pea were the most common LPs to encapsulate nutraceuticals and probiotics. The microencapsulation of probiotics using LPs improved bacteria survivability, storage stability, and tolerance in the in vitro GIT conditions. Moreover, homogenization and high-pressure pretreatments as well as enzymatic cross-linking of LPs significantly modify their structure and functionality to better encapsulate the bioactive core materials. LPs can be attractive delivery devices for the controlled release and increased bioaccessibility of the main food-grade bioactives.

Inhibition of Lipid and Protein Oxidation in Whey-Protein-Stabilized Emulsions Using a Natural Antioxidant: Black Rice Anthocyanins

The food industry is exploring the natural environment to identify botanical extracts that can be used as functional ingredients that can replace synthetic ingredients in foods. In the present study, the ability of black rice anthocyanins as natural antioxidants to inhibit both lipid and protein oxidation in protein-stabilized oil-in-water emulsions was examined. Whey-protein-stabilized emulsions were prepared containing 0, 0.02, 0.04, and 0.06% (w/v) anthocyanins, and then the impact of this plant-based extract on their physical and chemical stabilities was evaluated. The addition of the anthocyanins improved the physical stability of the emulsions in a dose-dependent manner by inhibiting droplet aggregation during storage (35 °C for 5 days). The anthocyanins also exhibited good antioxidant activity in a dose-dependent manner, as seen by their capacity for inhibiting both lipid oxidation (reduced lipid hydroperoxides and malondialdehyde) and protein oxidation (reduced carbonyl and Schiff base formation, intrinsic fluorescence loss, and molecular weight changes). Black rice anthocyanins may therefore be an effective botanical extract for improving the stability of protein-stabilized food emulsions by inhibiting oxidative reactions.

Comparison of legume and dairy proteins for the impact of Maillard conjugation on nanoemulsion formation, stability, and lutein color retention

While dairy proteins have traditionally been used to stabilize nanoemulsions, there is a trend towards plant-based formulations. Additionally, both types of protein are poorly soluble near their isoelectric point. The main goals of this research were to develop and characterize Maillard conjugates from pea protein (PPI) or caseinate and dextran, and to evaluate the physical stability of nanoemulsions made with such emulsifiers at various ionic strengths, pH = 4.6, and temperatures during storage, as well as lutein color retention over storage. Protein conjugates formed nanoemulsions with diameters of 125 ± 12 nm (PDI = 0.13 ± 0.00) and 269 ± 36 nm (PDI = 0.76 ± 0.42) (pH = 7) for caseinate and PPI, respectively. Conjugation improved the physical stability (droplet size) of emulsions at the isoelectric point, during storage at 4-55 °C, and in ionic solutions. Lutein color degradation was better associated with particle size than conjugation and was lowest for PPI-stabilized emulsions. This study suggests that Maillard conjugation could improve PPI emulsification properties.

Comparing DPPP fluorescence and UV based methods to assess oxidation degree of krill oil-in-water emulsions

In this study, lipid oxidation evaluation methods were compared for a krill-oil-in-water emulsion system. With this aim, thiocyanate and DPPP (diphenyl-1-pyrenylphosphine) fluorescence methods were comparatively examined to determine primary oxidation products. 2-thiobarbituric acid reactive substances (TBARS), hexanal and propanal formation were also monitored as secondary oxidations products. All oxidation experiments were performed via both auto-oxidation at 45 °C and light-riboflavin induced photooxidation at 37 °C. The results have shown that thiocyanate method was not suitable to measure lipid hydroperoxides by the both in auto- and photo-oxidation systems. On the other hand, fluorescence intensity of samples containing the DPPP probe increased during incubation period which indicates the formation of lipid hydroperoxides could be detected via this method. TBARS, hexanal and propanal concentrations also increased during storage period and the formation kinetics of secondary oxidation products was confirmed that the DPPP fluorescence method was accurate and reliable at different environmental conditions.

The health benefits, functional properties, modifications, and applications of pea (Pisum sativum L.) protein: Current status, challenges, and perspectives

In recent years, the development and application of plant proteins have drawn increasing scientific and industrial interests. Pea (Pisum sativum L.) is an important source of high-quality vegetable protein in the human diet. Its protein components are generally considered hypoallergenic, and many studies have highlighted the health benefits associated with the consumption of pea protein. Pea protein and its hydrolysates (pea protein hydrolysates [PPH]) possess health benefits such as antioxidant, antihypertensive, and modulating intestinal bacteria activities, as well as various functional properties, including solubility, water- and oil-holding capacities, and emulsifying, foaming, and gelling properties. However, the application of pea protein in the food system is limited due to its poor functional performances. Several frequently applied modification methods, including physical, chemical, enzymatic, and combined treatments, have been used for pea protein to improve its functional properties and expand its food applications. To date, different applications of pea protein in the food system have been extensively studied, for example, encapsulation for bioactive ingredients, edible films, extruded products and substitution for cereal flours, fats, and animal proteins. This article reviews the current status of the knowledge regarding pea protein, focusing on its health benefits, functional properties, and structural modifications, and comprehensively summarizes its potential applications in the food industry.

Development of Next-Generation Nutritionally Fortified Plant-Based Milk Substitutes: Structural Design Principles

Consumers are increasingly interested in decreasing their dietary intake of animal-based food products, due to health, sustainability, and ethical concerns. For this reason, the food industry is creating new products from plant-based ingredients that simulate many of the physicochemical and sensory attributes associated with animal-derived foods, including milk, eggs, and meat. An understanding of how the ingredient type, amount, and organization influence the desirable physicochemical, sensory, and nutritional attributes of these plant-based foods is required to achieve this goal. A potential problem with plant-based diets is that they lack key micronutrients, such as vitamin B12, vitamin D, calcium, and ω-3 fatty acids. The aim of this review is to present the science behind the creation of next-generation nutritionally fortified plant-based milk substitutes. These milk-like products may be formed by mechanically breaking down certain plant materials (including nuts, seeds, and legumes) to produce a dispersion of oil bodies and other colloidal matter in water, or by forming oil-in-water emulsions by homogenizing plant-based oils and emulsifiers with water. A brief overview of the formulation and fabrication of plant-based milks is given. The relationship between the optical properties, rheology, and stability of plant-based milks and their composition and structure is then covered. Approaches to fortify these products with micronutrients that may be missing from a plant-based diet are also highlighted. In conclusion, this article highlights how the knowledge of structural design principles can be used to facilitate the creation of higher quality and more sustainable plant-based food products.

Microencapsulation of rice bran oil using pea protein and maltodextrin mixtures as wall material

In this work, the encapsulation of rice bran oil extracted using supercritical CO2 has been studied. In the first stage, the emulsification process by high pressure homogenization was studied and optimized. The effect of the working pressure (60-150 MPa), the composition of the carrier (mixtures of pea protein isolate (PPI) and maltodextrin (MD), from 50 to 90% of PPI) and the carrier to oil ratio (2-4) on the emulsion droplet size (EDS) was studied. To minimize the EDS, moderate pressures (114 MPa), a carrier composed mainly by PPI (64%) and carrier to oil ratios around 3.2 were required. The emulsion obtained in the optimal conditions (EDS = 189 ± 3nm) was dried using different technologies (spray-drying, PGSS-drying and freeze drying). The supercritical CO2 based drying process (PGSS) provided spherical particles that resulted in the smallest average size (but broader distribution) and lower encapsulation efficiency (53 ± 2%).

Modulation of interfacial phenolic antioxidant distribution in Pickering emulsions via interactions between zein nanoparticles and gallic acid

The impacts of protein nanoparticles on the interfacial distribution of antioxidants and the oxidative stability in Pickering emulsions are attracting increasing research interests. In the present work, the distribution of gallic acid (GA) in zein nanoparticles-stabilized Pickering emulsions (ZPE) was determined by employing a pseudophase kinetic model. The interfacial distribution of GA was found to be favored in ZPEs with higher zein nanoparticle concentration (C_zein). Upon increasing C_zein, the interfacial loading of nanoparticles (Γ) dominated the modulation of %GA_I via hydrogen bonding between zein nanoparticles and GA. The interfacial percentage of GA (%GA_I) increased from 28% to 39% as Γ increased from 0.48 to 1.12 mg/m²_. In the presence of GA, a direct correlation between C_zein or Γ and oxidation stability was recognized, whereas the oxidative stability showed a non-linear dependence on either C_zein or Γ in the absence of GA. By excluding antioxidant effects of zein nanoparticles, we found that the %GA_I, which was regulated by Γ, took the leading role over the physical barrier effect on the oxidative stability of emulsions. The present work extends our current knowledge on how protein based nanoparticles manipulate the interfacial distribution of antioxidant and then affect the oxidative stability of emulsions.

Synthesis, physicochemical properties, and health aspects of structured lipids: A review

Structured lipids (SLs) refer to a new type of functional lipids obtained by chemically, enzymatically, or genetically modifying the composition and/or distribution of fatty acids in the glycerol backbone. Due to the unique physicochemical characteristics and health benefits of SLs (for example, calorie reduction, immune function improvement, and reduction in serum triacylglycerols), there is increasing interest in the research and application of novel SLs in the food industry. The chemical structures and molecular architectures of SLs define mainly their physicochemical properties and nutritional values, which are also affected by the processing conditions. In this regard, this holistic review provides coverage of the latest developments and applications of SLs in terms of synthesis strategies, physicochemical properties, health aspects, and potential food applications. Enzymatic synthesis of SLs particularly with immobilized lipases is presented with a short introduction to the genetic engineering approach. Some physical features such as solid fat content, crystallization and melting behavior, rheology and interfacial properties, as well as oxidative stability are discussed as influenced by chemical structures and processing conditions. Health-related considerations of SLs including their metabolic characteristics, biopolymer-based lipid digestion modulation, and oleogelation of liquid oils are also explored. Finally, potential food applications of SLs are shortly introduced. Major challenges and future trends in the industrial production of SLs, physicochemical properties, and digestion behavior of SLs in complex food systems, as well as further exploration of SL-based oleogels and their food application are also discussed.

Gum Arabic-Mediated Synthesis of Glyco-pea Protein Hydrolysate via Maillard Reaction Improves Solubility, Flavor Profile, and Functionality of Plant Protein

Pea protein hydrolysate (PPH) is successfully conjugated with gum arabic (GA) through Maillard-driven chemistry. The effect of cross-linking conjugation on the structure, solubility, volatile substances, emulsification, and antioxidative activity of glyco-PPH is investigated, and found to improve all properties. The formation of glyco-PPH is confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier-transform infrared (FTIR), and scanning electron microscopy (SEM). Size exclusion chromatography-multi angle light scattering (SEC-MALS) unveils that the maximum molecular mass of glyco-PPH occurs after 1 day of conjugation and approximately 1.2 mol of gum arabic conjugates on one mole of PPH. Headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) reveals the odor changes of glycoprotein before and after cross-linking. We have also prepared oil-in-water emulsions using glyco-PPH, which have enhanced physical stability against pH changes and chemical stability against lipid oxidation. The mechanism proposed involves Maillard-driven synthesis of the cross-linked PPH-GA conjugates, which increase the surface hydrophilicity and steric hindrance of glyco-PPH. These findings could provide a rational foundation for tailoring the physicochemical properties and functionalities of plant-based protein, which are attractive for food and functional materials applications.

Seed Protein of Lentils: Current Status, Progress, and Food Applications

Grain legumes are widely recognized as staple sources of dietary protein worldwide. Lentil seeds are an excellent source of plant-based proteins and represent a viable alternative to animal and soybean proteins for food processing formulations. Lentil proteins provide not only dietary amino acids but are also a source of bioactive peptides that provide health benefits. This review focuses on the current knowledge of seed protein, extraction and isolation methods, bioactive peptides, and food applications of lentil protein. Lentil is the most rapidly expanding crop for direct human consumption, and has potential for greater impact as a protein source for food processing applications. Improvements in lentil protein quality, amino acid composition, and processing fractions will enhance the nutritional quality of this rapidly expanding crop globally.

Effects of Enzymatic Hydrolysis of Fava Bean Protein Isolate by Alcalase on the Physical and Oxidative Stability of Oil-in-Water Emulsions

Fava bean protein isolate (FBPI) was hydrolyzed by Alcalase with different degrees of hydrolysis (DHs), and the role of hydrolysates in oil-in-water (O/W) emulsion stability was investigated. Four emulsions, DH0, DH4, DH9, and DH15, were prepared by 1% (w/v) FBPI hydrolysates with different DHs (0% as the control and 4, 9, and 15%) and 5% (w/v) purified rapeseed oil. The emulsions were monitored for physical and oxidative stability at 37 °C for 7 days. DH4 and DH0 exhibited better physical stability than DH9 and DH15, indicated by droplet size, morphology, and Turbiscan stability index. More importantly, FBPI hydrolysates with DH of 4% most effectively inhibited lipid oxidation (i.e., formation of conjugated dienes and hexanal) while maintaining protein oxidative stability compared to the native and extensively hydrolyzed FBPI. Higher DHs (9 and 15%) induced unduly decreased surface hydrophobicity and increased surface load, which might negatively affect the emulsifying activity. FBPI hydrolysates with DH of 4% had suitable molecular weight for better interfacial layer stability, increased surface net charge for more repulsive electrostatic force, and increased hydrophobicity for better adsorption at the interface and, therefore, may serve as potential natural emulsifiers to maintain both physical and oxidative stability of O/W emulsions.

Pea protein isolate-gum Arabic Maillard conjugates improves physical and oxidative stability of oil-in-water emulsions

The present work investigated the impact of incubation time (0, 1, 3, and 5 day) on the properties and functionalities of conjugates formed between pea protein isolate (PPI) and gum Arabic (GA). The participation of both 11S and 7S to form conjugates with GA was proved by SDS-PAGE. The degree of conjugation reaction of conjugated was characterized by measuring the formation of Maillard reaction products, the loss of free amino groups, and color changes. The results suggested that PPI intimately incorporated into GA after 1 day incubation, giving a non-homogeneous microstructure with a reduction of nearly 18% available free amino and an increase of relative solubility to 15.5%. Additionally, emulsions prepared by PPI-GA conjugates showed smaller particle size, higher surface charge, and stronger steric hindrance to stabilize the emulsion droplets against environmental stresses and lipid oxidation. The findings provide a practical means to improve the functionality of pea proteins.

Interfacial Antioxidants: A Review of Natural and Synthetic Emulsifiers and Coemulsifiers That Can Inhibit Lipid Oxidation

There has been strong interest in developing effective strategies to inhibit lipid oxidation in emulsified food products due to the need to incorporate oxidatively labile bioactive lipids, such as ω-3 fatty acids, conjugated linoleic acids, or carotenoids. Emulsifiers or coemulsifiers can be utilized to inhibit lipid oxidation in emulsions. Both of these molecular types can adsorb to droplet surfaces and inhibit lipid oxidation, but emulsifiers can also stabilize droplets against aggregation whereas coemulsifiers cannot. There are a host of existing emulsifiers, covalent conjugates, or physical complexes that have the potential to inhibit lipid oxidation by a variety of mechanisms. Existing emulsifiers with antioxidant potential consist of surfactants, phospholipids, proteins, polysaccharides, and colloidal particles. Conjugates and complexes are typically formed by covalently or physically linking together a surface-active molecule with an antioxidant molecule. This article reviews the molecular and physicochemical basis for the surface and antioxidant activities of emulsifiers and coemulsifiers, highlights the important properties of interfacial layers that can be engineered to control lipid oxidation, and outlines different kinds of existing emulsifiers, conjugates, and complexes that can be used to inhibit oxidation.