Not sequentially but simultaneously: Facile extraction of proteins and oleosomes from oilseeds

Thin liquid films stabilized by plant proteins: Implications for foam stability

HYPOTHESIS

Plant-based proteins offer a sustainable solution for stabilizing multiphase food materials like edible foams and emulsions. However, challenges in understanding and engineering plant protein-stabilized interfaces persist, mostly because of the commonly poorer functionality and complex composition of the respective protein isolates. We hypothesize that part of the limited understanding is related to the lack of experimental data on the length-scale of the thin liquid film that separates two neighboring bubbles. By conducting such experiments, we aim to better understand the mechanisms by which plant proteins stabilize foams, a critical material in food applications.

EXPERIMENTS

In this study, we employ the dynamic thin film balance method to study the equilibrium properties and dynamic drainage behavior of foam thin liquid films stabilized by proteins derived from two main plant protein sources, yellow peas and rapeseeds, to investigate potential differences in film stabilization.

FINDINGS

Our thin film results provide new insights into the general foam stabilization mechanism of the two plant proteins. Most studies in this field focus on the impact of surface rheological parameters on stability of plant protein-based foam. We show that for such foams the half-life scales linearly with film thickness, the latter being closely related to the steric and electrostatic interactions developed across the respective films in equilibrium. Our study demonstrates the value of thin film studies in complementing traditional methods for studying protein-stabilized interfaces and facilitates an understanding of foam stabilization mechanisms that are universal among various surface-active species.

Ultrafiltration of Rapeseed Protein Concentrate: Effect of Pectinase Treatment on Membrane Fouling

Membrane filtration technologies have shown great potential as a gentle and effective method for concentrating and fractionating proteins for food applications. However, the application of this technology to plant-derived protein streams is in its infancy. In this study, an aqueous rapeseed protein concentrate was obtained with wet milling, and its performance during ultrafiltration with two distinct molecular weight cut-offs (10 and 100 kDa) was tested. All rapeseed proteins were retained during filtration. The addition of pectinase during extraction prior to filtration caused important structural modifications to the extract, resulting in increased permeate fluxes, increased carbohydrate permeation and a reduction in irreversible fouling. Lager pore sizes led to more pronounced fouling. FTIR analysis of the spent membranes showed that proteins and lipids are causing irreversible fouling.

Oil-water interface and emulsion stabilising properties of rapeseed proteins napin and cruciferin studied by nonlinear surface rheology

HYPOTHESIS

Two major protein families are present in rapeseed, namely cruciferins and napins. The structural differences between the two protein families indicate that they might behave differently when their mixture stabilises oil-water interfaces. Therefore, this work focuses on elucidating the role of both proteins in interface and emulsion stabilisation.

EXPERIMENTS

Protein molecular properties were evaluated, using SEC, DSC, CD, and hydrophobicity analysis. The oil-water interface mechanical properties were studied using LAOS and LAOD. General stress decomposition (GSD) was used as a novel method to characterise the nonlinear response. Additionally, to evaluate the emulsifying properties of the rapeseed proteins, emulsions were prepared using pure napins or cruciferin and also their mixtures at 1:3, 1:1 and 3:1 (w:w) ratios.

FINDINGS

Cruciferins formed stiff viscoelastic solid-like interfacial layers (Gs' = 0.046 mN/m; Ed' = 30.1 mN/m), while napin formed weaker and more stretchable layers at the oil-water interface (Gs' = 0.010 mN/m; Ed' = 26.4 mN/m). As a result, cruciferin-formed oil droplets with much higher stability against coalescence (coalescence index, CI up to 10%) than napin-stabilised ones (CI up to 146%) during two months of storage. Both proteins have a different role in emulsions produced with napin-cruciferin mixtures, where cruciferin provides high coalescence stability, while napin induces flocculation. Our work showed the role of each rapeseed protein in liquid-liquid multiphase systems.

The mechanism of encapsulating curcumin into oleosomes (Lipid Droplets)

Organisms have evolved intracellular micron-sized lipid droplets to carry and protect lipids and hydrophobic minor compounds in the hydrophilic environment of cells. These droplets can be utilized as carriers of hydrophobic therapeutics by taking advantage of their biological functions. Here, we focus on the potential of plant-derived lipid droplets, known as oleosomes, as carriers for hydrophobic therapeutics, such as curcumin. By spectroscopy and confocal microscopy, we demonstrate that the oleosome membrane is permeable to hydrophobic curcumin molecules. Fluorescence recovery after photobleaching shows rapid curcumin diffusion towards oleosomes, with a diffusion time in the range of seconds. Following this, quenching probes and dilatational rheology reveal that part of the loaded curcumin molecules can accumulate at the oleosome interface, and the rest settle in the inner core. Our findings shed light on the loading mechanism of the plant-derived lipid droplets and underscore the significance of molecular localization for understanding the mechanism. This work not only enhances the understanding of the loading process but also shows potential for oleosomes use as lipid carriers.

Artificial oil bodies: A review on composition, properties, biotechnological applications, and improvement methods

In order to simulate the structure of natural oil body, artificial oil bodies (AOBs) are fabricated by the integration of oleosins, triacylglycerols (TAGs) and phospholipids (PLs) in vitro. Recently, AOBs have gained great research interest both in the food and biological fields due to its ability to act as a novel delivery system for bioactive compounds and as a carrier for target proteins. This review aims to summarize the composition and the preparation methods of AOBs, examine the factors influencing their stability. Moreover, this contribution focusses on exploring the application of AOBs to encapsulate functional ingredients that are prone to oxidation as well as improve efficiency involved in protein purification, renaturation and immobilization by reducing the complex steps. In addition, the improvement measures to further enhance the stability and efficacy of AOBs are also discussed. The application of AOBs is expected to be a big step towards replacing existing bioreactors and delivery systems.

Pectin polysaccharide contribution to oleosome extraction after wet milling of rapeseed

Oleosomes are lipid composites providing energy storage in oilseeds. They possess a unique structure, comprised of a triglyceride core stabilized by a phospholipid-protein membrane, and they have shown potential to be used as ingredients in several food applications. Intact oleosomes are extracted by an aqueous process which includes soaking, milling, and gravitational separation. However, the details of the complexes formed between oleosomes, proteins and pectin polysaccharides during this extraction are not known. It was hypothesized that pectins play an important role during the oleosome separation, and different proteins will be complexed on the surface of the oleosomes, depending on the pH of extraction. Rapeseed extracts were treated with and without pectinase (Pectinex Ultra SP-L) and extracted at pH 5.7 or 8.5, as this will affect electrostatic complexation. Acidic conditions led to co-extraction of storage proteins, structured as dense oleosome emulsions, stabilized by a network of proteins and polysaccharides. Pectinase intensified this effect, highlighting pectic polysaccharides' role in bridging interactions among proteins and oleosomes under acidic conditions. The presence of this dense interstitial layer around the oleosomes protected them from coalescence during extraction. Conversely, under alkaline conditions, the extraction process yielded more purified oleosomes characterized by a larger particle size, most likely due to coalescence. Nevertheless, pectinase addition at pH 8.5 mitigated coalescence tendencies. These results contribute to a better understanding of the details of the colloidal complexes formed during extraction and can be used to modulate the composition of the extracted fractions, with significant consequences not only for yields and purity but also for the functional properties of the ingredients produced.

A Review of the Utilization of Canola Protein as an Emulsifier in the Development of Food Emulsions

Canola is the second-largest cultivated oilseed crop in the world and produces meal consisting of about 35-40% proteins. Despite this, less than 1% of the global plant-based protein market is taken up by canola protein. The reason behind such underutilization of canola protein and its rapeseed counterpart could be the harsh conditions of the industrial oil extraction process, the dark colour of the meal, the presence of various antinutrients, the variability in the protein composition based on the source, and the different properties of the two major protein components. Although academic research has shown immense potential for the use of canola protein and its rapeseed counterpart in emulsion development and stabilization, there is still a vast knowledge gap in efficiently utilizing canola proteins as an effective emulsifier in the development of various emulsion-based foods and beverages. In this context, this review paper summarizes the last 15 years of research on canola and rapeseed proteins as food emulsifiers. It discusses the protein extraction methods, modifications made to improve emulsification, emulsion composition, preparation protocols, and emulsion stability results. The need for further improvement in the scope of the research and reducing the knowledge gap is also highlighted, which could be useful for the food industry to rationally select canola proteins and optimize the processing parameters to obtain products with desirable attributes.

Walnut (Juglans regia L.) kernel oil bodies recovered by aqueous extraction for utilization as ingredient in food emulsions: Exploration of their microstructure, composition and the effects of homogenization, pH, and salt ions on their physical stability

Natural oil-in-water emulsions containing plant oil bodies (OBs), also called oleosomes, rich in health-promoting omega-3 polyunsaturated fatty acids (ω3 PUFA) are of increasing interest for food applications. In this study, we focused on walnut kernel OBs (WK-OBs) and explored their microstructure, composition and physical stability in ionic environments as well as the impact of homogenization. A green process involving aqueous extraction by grinding of WK allowed the co-extraction of OBs and proteins, and centrifugation was used to recover the WK-OBs. Confocal laser scanning microscopy images showed the spherical shape of WK-OBs with an oil core envelopped by a layer of phospholipids (0.16 % of lipids) and embedded proteins. Their mean diameter was 5.1 ± 0.3 µm. The WK-OBs contained 70.1 % PUFA with 57.8 % ω6 linoleic acid and 12.3 % ω3 α-linolenic acid representing 68 % and 11.6 % of the total fatty acids in the sn-2 position of the triacylglycerols (TAG), respectively. Trilinolein was the main TAG (23.1 %). The WK-OBs also contained sterols (1223 ± 33 mg/kg lipids; 86 % β-sitosterol), carotenoids (0.62 ± 0.01 mg/kg lipids; 49.2 % β-carotene), and tocopherols (322.7 ± 7.7 mg/kg lipids; 89 % γ-tocopherol), confirming their interest as health-promoting ingredients. The decrease in the size of WK-OBs under high-pressure homogenization avoided phase separation upon storage. The anionic WK-OB surface at neutral pH was affected by stressful ionic environments (pH, NaCl, CaCl2), that induced aggregation of WK-OBs and decreased the physical stability of the emulsions. Emulsions containing WK-OBs are promising to diversify the market of the ω3-rich plant-based food products and beverages.

Enhancing Rheological and Textural Properties of Gelatin-Based Composite Gels through Incorporation of Sesame Seed Oleosome-Protein Fillers

In this study, the protein and oleosomes of sesame seeds were extracted individually and used to prepare a gel composed of gelatin, protein, and oleosomes. Mixtures of gelatin and sesame seeds protein were prepared, and oleosomes with different percentages (0, 10, 20 and 30% of their weight) were used. Different amounts of oleosomes in the composite gel samples were examined for their morphological, rheological, and textural properties. The results of the viscoelastic properties of different composite gel samples indicated that a higher percentage of oleosomes would increase the storage modulus (G'), loss modulus (G″), and complex viscosity (η*). The storage modulus of all gel samples was greater than the loss modulus, suggesting a solid behavior. So, in the sample with 30% oleosome, the storage modulus and the loss modulus reached 143,440 Pascals and 44,530 Pascals. The hardness and breaking force in samples containing 30% oleosome reached 1.29 ± 0.02 and 0.17 ± 0.02, respectively. In general, it can be said that composite gels based on gelatin-sesame seed protein modified with oleosome can be used as a part of food components in various dairy products, gelatin desserts, lean meat products and the production of useful products.

The emulsifying ability of oleosomes and their interfacial molecules

Oleosomes are natural oil droplets, present in all organisms and abundant in oilseeds. After their aqueous extraction from oilseeds, they can be directly utilized as oil droplets in food, cosmetics and all types of oil-in-water emulsion systems. However, to expand the potential uses of oleosomes as green ingredients and to valorize oilseeds as efficient as possible, we explored their emulsifying ability. Oleosomes were extracted from rapeseeds, and 10.0 wt% oil-in-water emulsions were created after homogenization with 0.5-6.0 wt% oleosomes, and the droplet size of the emulsions and their structure was measured by laser diffraction and confocal laser scanning microscopy (CLSM), respectively. The emulsion with an oleosome concentration lower than 1.0 wt% gave unstable emulsions with visible free oil. At oleosome concentrations at 1.5 wt% or higher, we obtained stable emulsions with droplet sizes between 2.0 and 12.0 µm. To investigate the role of the oleosome interfacial molecules in stabilizing emulsions we also studied their emulsifying and interfacial properties (using drop tensiometry) after isolating them from the oleosome structure. Both oleosomes and their isolated interfacial molecules exhibited a similar behavior on the oil-water interfaces, forming predominantly elastic interfacial films, and also showed a similar emulsifying ability. Our results show that oleosomes are not stabilizing the oil-in-water emulsions as intact particles, but they provide their interfacial molecules, which are enough to stabilize an oil-water surface up to about 2 times bigger than the initial oleosome surface. The understanding of the behavior of oleosomes as emulsifiers, opens many possibilities to use oleosomes as alternative to synthetic emulsifiers in food and pharma applications.

Effects of Concentration and Type of Lipids on the Droplet Size, Encapsulation, Colour and Viscosity in the Oil-in-Water Emulsions Stabilised by Rapeseed Protein

The objective of this study was to extract the rapeseed protein from by-products and further examine the effect of lab-made rapeseed protein on the droplet size, microstructure, colour, encapsulation and apparent viscosity of emulsions. Rapeseed protein-stabilised emulsions with an increasing gradient of milk fat or rapeseed oil (10, 20, 30, 40 and 50%, v/v) were fabricated using a high shear rate homogenisation. All emulsions showed 100% oil encapsulation for 30 days of storage, irrespective of lipid type and the concentration used. Rapeseed oil emulsions were stable against coalescence, whereas the milk fat emulsion showed a partial micro-coalescence. The apparent viscosity of emulsions raised with increased lipid concentrations. Each of the emulsions showed a shear thinning behaviour, a typical behaviour of non-Newtonian fluids. The average droplet size was raised in milk fat and rapeseed oil emulsions when the concentration of lipids increased. A simple approach to manufacturing stable emulsions offers a feasible hint to convert protein-rich by-products into a valuable carrier of saturated or unsaturated lipids for the design of foods with a targeted lipid profile.

Mild Fractionation for More Sustainable Food Ingredients

With the rising problems of food shortages, energy costs, and raw materials, the food industry must reduce its environmental impact. We present an overview of more resource-efficient processes to produce food ingredients, describing their environmental impact and the functional properties obtained. Extensive wet processing yields high purities but also has the highest environmental impact, mainly due to heating for protein precipitation and dehydration. Milder wet alternatives exclude, for example, low pH-driven separation and are based on salt precipitation or water only. Drying steps are omitted during dry fractionation using air classification or electrostatic separation. Benefits of milder methods are enhanced functional properties. Therefore, fractionation and formulation should be focused on the desired functionality instead of purity. Environmental impact is also strongly reduced by milder refining. Antinutritional factors and off-flavors remain challenges in more mildly produced ingredients. The benefits of less refining motivate the increasing trend toward mildly refined ingredients.

A review of the structure, function, and application of plant-based protein-phenolic conjugates and complexes

Interactions between plant-based proteins (PP) and phenolic compounds (PC) occur naturally in many food products. Recently, special attention has been paid to the fabrication of PP-PC conjugates or complexes in model systems with a focus on their effects on their structure, functionality, and health benefits. Conjugates are held together by covalent bonds, whereas complexes are held together by noncovalent ones. This review highlights the nature of protein-phenolic interactions involving PP. The interactions of these PC with the PP in model systems are discussed, as well as their impact on the structural, functional, and health-promoting properties of PP. The PP in conjugates and complexes tend to be more unfolded than in their native state, which often improves their functional attributes. PP-PC conjugates and complexes often exhibit improved in vitro digestibility, antioxidant activity, and potential allergy-reducing activities. Consequently, they may be used as antioxidant emulsifiers, edible film additives, nanoparticles, and hydrogels in the food industry. However, studies focusing on the application of PP-PC conjugates and complexes in real foods are still scarce. Further research is therefore required to determine the structure-function relationships of PP-PC conjugates and complexes that may influence their application as functional ingredients in the food industry.

Fabrication and Characterization of Botanical-Based Double-Layered Emulsion: Protection of DHA and Astaxanthin Based on Interface Remodeling

Both DHA and astaxanthin, with multiple conjugated double bonds, are considered as health-promoting molecules. However, their utilizations into food systems are restricted due to their poor water solubility and high oxidizability, plus their certain off-smell. In this study, the interactions between perilla protein isolate (PPI) and flaxseed gum (FG) were firstly investigated using multiple spectroscopies, suggesting that hydrophobic, electrostatic force and hydrogen bonds played important roles. Additionally, double-layer emulsion was constructed by layer-by-layer deposition technology and exhibited preferable effects on masking the fishy smell of algae oil. Calcium ions also showed an improving effect on the elasticity modulus of O/W emulsions and was managed to significantly protect the stability of co-delivered astaxanthin and DHA, without additional antioxidants during storage for 21 days. The vegan system produced in this study may, therefore, be suitable for effective delivery of both ω-3 fatty acid and carotenoids for their further incorporation into food systems, such as plant-based yoghourt, etc.

Plant oil bodies and their membrane components: new natural materials for food applications

Plants store triacylglycerols in the form of oil bodies (OBs) as an energy source for germination and subsequent seedling growth. The interfacial biomaterials from these OBs are called OB membrane materials (OBMMs) and have several applications in foods, e.g., as emulsifiers. OBMMs are preferred, compared with their synthetic counterparts, in food applications as emulsifiers because they are natural, i.e., suitable for clean label, and may stabilize bioactive components during storage. This review focuses mainly on the extraction technologies for plant OBMMs, the functionality of these materials, and the interaction of OB membranes with other food components. Different sources of OBs are evaluated and the challenges during the extraction and use of these OBMMs for food applications are addressed.

Industrial hemp seed: from the field to value-added food ingredients

Industrial hemp, with low levels of the intoxicating cannabinoid tetrahydrocannabinol (THC), is grown for fibre and seeds. The industrial hemp industry is poised for expansion. The legalisation of industrial hemp as an agricultural commodity and the inclusion of hemp seed in foods is helping to drive the expansion of the hemp food ingredients industry. This paper discusses the opportunity to build an industrial hemp industry, with a focus on the prospects of hemp seed and its components in food applications. The market opportunities for industrial hemp products are examined. Various aspects of the science that underpins the development of an industrial hemp industry through the food supply chain are presented. This includes a discussion on the agronomy, on-farm and post-harvest considerations and the various types of food ingredients that can be made from hemp seed. The characteristics of hemp seed meal, hemp seed protein and hemp seed oil are reviewed. Different processes for production of value-added ingredients from hemp seed, hemp seed oil and hemp seed protein, are examined. The applicability of hemp seed ingredients in food applications is reviewed. The design of hemp seed ingredients that are fit-for-purpose for target food applications, through the selection of varieties and processing methods for production of various hemp seed ingredients, needs to consider market-led opportunities. This will require an integrated through chain approach, combined with the development of on-farm and post-farm strategies, to ensure that the hemp seed ingredients and foods containing hemp seed are acceptable to the consumer.

NaCl induces flocculation and lipid oxidation of soybean oil body emulsions recovered by neutral aqueous extraction

BACKGROUND

Soybean oil bodies (SOB) are naturally pre-emulsified lipid droplets recovered directly from soybean seeds. Almost all food emulsions contain salts. However, it was not clear how the incorporation of salts affected the physicochemical stability of SOB.

RESULTS

This study investigated the effect of NaCl (0-1.2%) on the physical and oxidative stability of SOB emulsions under neutral (pH 7) and acidic (pH 3) conditions. In the presence of NaCl, the SOB emulsion (pH 7) showed strong flocculation during storage due to electrostatic screening. The NaCl-induced flocculation of SOB was attenuated at pH 3, which may be due to the difference in conformation or interaction of the protein interfaces covering SOB at different pH values. The increase in ionic strength or acid conditioning treatment resulted in a remarkable increase in the stability of SOB emulsions against coalescence. The confocal laser scanning microscopy images also confirmed the NaCl-induced changes in the flocculation/coalescence properties of SOB. The oxidative behavior tests indicated that SOB emulsions containing NaCl were more susceptible to lipid oxidation but protein oxidation was inhibited due to electrostatic screening, which reduced pro-oxidant accessibility of unadsorbed proteins in the emulsion. This oxidative behavior was attenuated at pH 3.

CONCLUSION

The incorporation of NaCl significantly reduced the physical and oxidative stability of the SOB emulsion, and acidic pH mitigated NaCl-induced flocculation and lipid oxidation of SOB. © 2021 Society of Chemical Industry.

Oil bodies extracted from high-oil soybeans (Glycine max) exhibited higher oxidative and physical stability than oil bodies from high-protein soybeans

Reports concerning the characteristics of soybean oil bodies (SOBs) isolated from high protein genotypes and high oil genotypes of soybeans available in the literature are insufficient and limiting. In this study, fatty acid compositions, total phenol and tocopherol contents, antioxidant capacity, and physicochemical stability of SOB emulsions recovered from three high-protein and three high-oil genotype soybeans were comparatively investigated. Principal component analysis showed that all six SOB samples could be easily discriminated based on the cultivar characteristics. Overall, the SOBs derived from the high-protein soybeans exhibited higher polyunsaturated fatty acid (PUFA) contents, while the SOBs derived from the high-oil soybeans had higher extraction yields and tocopherol contents; the tocopherol content was also positively correlated with the antioxidant capacity of the lipophilic fraction, but the difference in the total phenolic content between the two genotypes was not significant. The SOBs derived from the high-protein soybeans were more easily oxidized during storage, with 1.38- and 4-fold higher accumulation rates of lipid hydroperoxides (LPO) and thiobarbituric acid reactive substances (TBARS), respectively, in the high-protein-derived SOBs than in the high-oil-derived SOBs. In addition, the SOBs from the high-protein soybeans exhibited pronounced coalescence during storage, which was corroborated by focused confocal microscopy. These results confirmed that SOBs obtained from high-oil soybean genotypes are more suitable to manufacture OB-based products due to their superior physicochemical stability.

Composition of flesh lipids and oleosome yield optimization of selected sea buckthorn (Hippophae rhamnoides L.) cultivars grown in Poland

Sea buckthorn berries contain lipids rich in palmitoleic acid, carotenoids, tocols and sterols, but their composition varies greatly depending on the cultivar and region of cultivation. Therefore, the current study presents the chemical composition of fruit flesh oils of cultivars grown in Poland and compares them with plants grown worldwide. Among tested cultivars, the highest shares of palmitoleic acid were determined in Golden Rain and Luczystaja cvs. Ten grams of sea buckthorn flesh oil provides at least 28% of vitamin A, 50% of vitamin E and 5% of sterols of the recommended dietary allowance (RDA) values for adults. The final part of this study is dedicated to a preliminary study of the optimization of the oleosome yield by the centrifugation method. The maximum oleosome yield can be obtained at a relatively low centrifugal force (below 8000×g), while optimal temperature and time should be laboratory determined for each cultivar.

Deciphering the properties of hemp seed oil bodies for food applications: Lipid composition, microstructure, surface properties and physical stability

Hemp seed oil bodies (HSOBs) are of growing interest in response to the demand of consumers for healthy and natural plant-based food formulations. In this study, we used minimal processing including aqueous extraction by grinding and centrifugation to obtain HSOBs. We determined the lipid composition of HSBOs, their microstructure, and the impact of the homogenization pressure, pH and minerals on their surface properties and the physical stability of the emulsions. HSOBs contain high levels of well-balanced PUFA with LA/ALA = 2.9, γ-tocopherol, lutein and phytosterols. The mean diameter of HSOBs was 2.3 ± 0.1 μm with an isoelectric point in the range of pH 4.4 to 4.6. Homogenization of hemp seed extracts induced a decrease in the size of HSOBs but did not eliminate the sedimentation of the protein bodies composed of the globulin edestin. By changing the surface properties of HSOBs, pH values below 6 and NaCl induced the aggregation of HSOBs, while CaCl₂ induced both aggregation and membrane-fusion mediated coalescence of HSOBs by involving probably the anionic phospholipids together with membrane proteins. This study will contribute to extend the range of novel food products and designed emulsions containing hemp seed proteins and oil bodies.

Effects of pH on the Composition and Physical Stability of Peanut Oil Bodies from Aqueous Enzymatic Extraction

Peanut oil body (POB), which is rich in unsaturated fatty acids and bioactive substances, is widely used in cosmetics, food, and medicine. Compared with synthetic emulsifiers, peanut oil bodies have health advantages as natural emulsions. The physicochemical properties of oil bodies affect their food processing applications. To improve peanut oil body yield, cell-wall-breaking enzymes were screened for aqueous enzymatic extraction. The optimum conditions were as follows: enzymatic hydrolysis time, 2 h; material-to-liquid ratio, 1 : 5 ( $m/v$ ); enzyme concentration, 2% ( $v/m$ ); and temperature, 50°C. Oil body stability was closely related to pH. With increasing pH, the average particle size and zeta-potential of the oil bodies increased, indicating aggregation, as confirmed by microstructure analysis. At pH 11, exogenous proteins at the oil body interface were eluted, leaving endogenous proteins, which led to a decreased interfacial protein content and oil body aggregation. Therefore, oil body stability decreased under alkaline pH conditions, but no demulsification occurred.

Non-animal proteins as cutting-edge ingredients to reformulate animal-free foodstuffs: Present status and future perspectives

Consumer interest in protein rich diets is increasing, with more attention being paid to the protein source. Despite the occurrence of animal proteins in the human diet, non-animal proteins are gaining popularity around the world due to their health benefits, environmental sustainability, and ethical merit. These sources of protein qualify for vegan, vegetarian, and flexitarian diets. Non-animal proteins are versatile, derived mainly from cereals, vegetables, pulses, algae (seaweed and microalgae), fungi, and bacteria. This review's intent is to analyze the current and future direction of research and innovation in non-animal proteins, and to elucidate the extent (limitations and opportunities) of their applications in food and beverage industries. Prior knowledge provided relevant information on protein features (processing, structure, and techno-functionality) with particular focus on those derived from soy and wheat. In the current food landscape, beyond conventionally used plant sources, other plant proteins are gaining traction as alternative ingredients to formulate animal-free foodstuffs (e.g., meat alternatives, beverages, baked products, snack foods, and others). Microbial proteins derived from fungi and algae are also food ingredients of interest due to their high protein quantity and quality, however there is no commercial food application for bacterial protein yet. In the future, key points to consider are the importance of strain/variety selection, advances in extraction technologies, toxicity assessment, and how this source can be used to create food products for personalized nutrition.

On the Emulsifying Properties of Self-Assembled Pea Protein Particles

Pea proteins are promising oil-in-water emulsifying agents at both neutral and acidic conditions. In an acidic environment, pea proteins associate to form submicrometer-sized particles. Previous studies suggested that the emulsions at acidic pH were stabilized due to a Pickering mechanism. However, protein particles can be in equilibrium with protein molecules, which could play a significant role in the stabilization of emulsion droplets. Therefore, we revisited the emulsion stabilization mechanism of pea proteins at pH 3 and investigated whether the protein particles or the protein molecules are the major emulsifying agent. The theoretical and experimental surface load of dispersed oil droplets were compared, and we found that protein particles can cover only 3.2% of the total oil droplet surface, which is not enough to stabilize the droplets, whereas protein molecules can cover 47% of the total oil droplet surface. Moreover, through removing protein particles from the mixture and emulsifying with only protein molecules, the contributions of pea protein molecules to the emulsifying properties of pea proteins at pH 3 were evaluated. The results proved that the protein molecules were the primary stabilizers of the oil droplets at pH 3.

Nature-Assembled Structures for Delivery of Bioactive Compounds and Their Potential in Functional Foods

Consumers are demanding more natural, healthy, and high-quality products. The addition of health-promoting substances, such as bioactive compounds, to foods can boost their therapeutic effect. However, the incorporation of bioactive substances into food products involves several technological challenges. They may have low solubility in water or poor stability in the food environment and/or during digestion, resulting in a loss of their therapeutic properties. Over recent years, the encapsulation of bioactive compounds into laboratory-engineered colloidal structures has been successful in overcoming some of these hurdles. However, several nature-assembled colloidal structures could be employed for this purpose and may offer many advantages over laboratory-engineered colloidal structures. For example, the casein micelles and milk fat globules from milk and the oil bodies from seeds were designed by nature to deliver biological material or for storage purposes. These biological functional properties make them good candidates for the encapsulation of bioactive compounds to aid in their addition into foods. This review discusses the structure and biological function of different nature-assembled carriers, preparation/isolation methods, some of the advantages and challenges in their use as bioactive compound delivery systems, and their behavior during digestion.

Adsorption of rapeseed proteins at oil/water interfaces. Janus-like napins dominate the interface

Plants offer a vast variety of protein extracts, typically containing multiple species of proteins that can serve as building blocks of soft materials, like emulsions. However, the role of each protein species concerning the formation of emulsions and interfaces with diverse rheological properties is still unknown. Therefore, deciphering the role of the individual proteins in an extract is highly relevant, since it determines the optimal level of purification, and hence the sustainability aspects of the extract. Here, we will show that when oil/water emulsions were prepared with a rapeseed protein extract containing napins and cruciferins (in a mass ratio of 1:1), only napins adsorbed at the interface exhibiting a soft solid-like rheological behavior. The dominance of napins at the interface was ascribed to their small size (radius r = 1.7 nm) and its unique Janus-like structure, as 45% of the amino acids are hydrophobic and primarily located at one side of the protein. Cruciferins with a bigger size (r = 4.4 nm) and a more homogeneous distribution of the hydrophobic domains couldn't reach the interface, but they appear to just weakly interact with the adsorbed layer of napins.