Heat induced denaturation, aggregation and gelation of almond proteins in skim and full fat almond milk

Modulation of physico-chemical and technofunctional properties of quinoa protein isolate: Effect of precipitation acid

The typically low solubility and gelation capacity of plant proteins can impose challenges in the design of high-quality plant-based foods. The acid used during the precipitation step of plant protein isolate extraction can influence protein functionality. Here, acetic acid and citric acid were used to extract quinoa protein isolate (QPI) from quinoa flour, as these acids are more kosmotropic than the commonly used HCl, promoting the stabilisation of the native protein structure. While proximate analysis showed that total protein was similar for the three isolates, precipitation with kosmotropic acids increased soluble protein, which correlated positively with gel strength. Microstructure analysis revealed that these gels contained a less porous protein network with lipid droplet inclusions. This study shows that the choice of precipitation acid offers an opportunity to tailor the properties of quinoa protein isolate for application, a strategy that is likely applicable to other plant protein isolates.

Almond protein as Pickering emulsion stabilizer: Impact of microgel fabrication method and pH on emulsion stability

We evaluated the ability of almond proteins to produce Pickering emulsions (EM) stabilized by microgels (MG) fabricated by three different methods (heat treatment-HT, crosslinking with transglutaminase-TG or calcium-CA), at two pH levels (pH 3 or 7). Compared to pH 7, acidic pH significantly denatured almond proteins (ellipticity ∼0 mdeg), decreased absolute zeta potential values (10.5 to 18.6 mV at pH 3 and - 24.6 to -32.6 mV at pH 7), and free thiol content (114.64-131.60 μmol SH/g protein at pH 3 and 129.46-148.17 μmol SH/g protein at pH 7 - except in CA-crosslinked microgels, p > 0.05). These changes led to larger microgel sizes (D3,2pH3: 26.3-39.5 μm vs. D3,2pH7: 5.9-9.0 μm) with lower polydispersity (SpanpH3: ∼ 1.94 vs. SpanpH7: 2.32, excluding CA-based samples). Consequently, the Turbiscan Stability Index (TSI) was higher in acidic conditions for all emulsions, except for the calcium-containing formulation (EM_CApH3), emphasizing the critical role of calcium binding in maintaining emulsion stability in acidic environments. Microgels prepared via the traditional heat treatment method produced emulsions with intermediate stability (TSI ranging from 3.4 % to 5.1 % at 28 days of storage). Conversely, TG-crosslinked microgels led to unstable emulsions at pH 3, likely due to the lowest zeta potential (+4.2 mV), whereas at pH 7, the greatest stability was attributed to bridging flocculation that created a stable gel-like structure. Indeed, emulsions with lower TSI (EM_CApH3 = 1.8 %, EM_CApH7 = 2.3 % and EM_TGpH7 = 1.0 %, at 28 days of storage) also exhibited higher elastic modulus (G') over frequency sweep, indicating that the strong elastic network was relevant for emulsion stability (up to 28 days). This study, for the first time, demonstrated the production of stable almond-based Pickering emulsions, with properties modulated by the pH and method used to fabricate the microgels.

Genipin, a natural blue colorant precursor: Source, extraction, properties, and applications

Natural cross-linkers are extensively employed due to their low toxicity and biocompatibility benefits. Genipin acts as a precursor for producing blue colorants. The formation of these colorants involves the cross-linking reaction between genipin and primary amines present in amino acids, peptides, and proteins. Genipin is extracted from Gardenia jasminoides and Genipa americana. This article explains the cross-linking mechanism of genipin with proteins/polysaccharides to provide an overall understanding of its properties. Furthermore, it explores new sources of genipin and innovative methodologies to make the genipin recovery process efficient. Genipin increases food products' texture, gel strength, stability, and shelf life. The antibacterial, anti-inflammatory, and antioxidant properties of chitosan, gelatin, alginate, and hyaluronic acid increased after genipin cross-linking. Lastly, drawbacks, toxicity, and directions regarding the genipin cross-linking have also been addressed. The review article covers how to recover and cross-link genipin with biopolymers for industrial applications.

Trends and prospects in dairy protein replacement in yogurt and cheese

There is a growing demand for nutritional, functional, and eco-friendly dairy products, which has increased the need for research regarding alternative and sustainable protein sources. Plant-based, single-cell (SCP), and recombinant proteins are being explored as alternatives to dairy proteins. Plant-Based Proteins (PBPs) are commonly used to replace total dairy protein. However, PBPs are generally mixed with dairy proteins to improve their functional properties, which makes them dependent on animal protein sources. In contrast, single-Cell Proteins (SCPs) and recombinant dairy proteins are promising alternatives for dairy protein replacement since they provide nutritional components, essential amino acids, and high protein yield and can use industrial and agricultural waste as carbon sources. Although alternative protein sources offer numerous advantages over conventional dairy proteins, several technical and sensory challenges must be addressed to fully incorporate them into cheese and yogurt products. Future research can focus on improving the functional and sensory properties of alternative protein sources and developing new processing technologies to optimize their use in dairy products. This review highlights the current status of alternative dairy proteins in cheese and yogurt, their functional properties, and the challenges of their use in these products.

New Route to the Production of Almond Beverages Using Hydrodynamic Cavitation

Perceived as a healthy food, almond beverages are gaining ever-increasing consumer preference across nonalcoholic vegetable beverages, ranking in first place among oilseed-based drinks. However, costly raw material; time and energy consuming pre- and posttreatments such as soaking, blanching and peeling; and thermal sterilization hinder their sustainability, affordability and spread. Hydrodynamic cavitation processes were applied, for the first time, as a single-unit operation with straightforward scalability, to the extraction in water of almond skinless kernels in the form of flour and fine grains, and of whole almond seeds in the form of coarse grains, up to high concentrations. The nutritional profile of the extracts matched that of a high-end commercial product, as well as showing nearly complete extraction of the raw materials. The availability of bioactive micronutrients and the microbiological stability exceeded the commercial product. The concentrated extract of whole almond seeds showed comparatively higher antiradical activity, likely due to the properties of the almond kernel skin. Hydrodynamic cavitation-based processing might represent a convenient route to the production of conventional as well as integral and potentially healthier almond beverages, avoiding multiple technological steps, while affording fast production cycles and consuming less than 50 Wh of electricity per liter before bottling.

Ultrasound-induced protein restructuring and ordered aggregation to form amyloid crystals

Amyloid crystals, a form of ordered protein aggregates documented relatively recently, have not been studied as extensively as amyloid fibres. This study investigates the formation of amyloid crystals with low frequency ultrasound (20 kHz) using β-lactoglobulin, as a model protein for amyloid synthesis. Acoustic cavitation generates localised zones of intense shear, with extreme heat and pressure that could potentially drive the formation of amyloid structures at ambient bulk fluid temperatures (20 ± 1 °C). Thioflavin T fluorescence and electron microscopy showed that low-frequency ultrasound at 20 W/cm3 input power induced β-stacking to produce amyloid crystals in the mesoscopic size range, with a mean length of approximately 22 µm. FTIR spectroscopy indicated a shift towards increased intermolecular antiparallel β-sheet content. An increase in sonication time (0-60 min) and input power (4-24 W/cm3) increased the mean crystal length, but this increase was not linearly proportional to sonication time and input power due to the delayed onset of crystal growth. We propose that acoustic cavitation causes protein unfolding and aggregation and imparts energy to aggregates to cross the torsion barrier, to achieve their lowest energy state as amyloid crystals. The study contributes to a further understanding of protein chemistry relating to the energy landscape of folding and aggregation. Ultrasound presents opportunities for practical applications of amyloid structures, presenting a more adaptable and scalable approach for synthesis.

Soy and whey protein isolate mixture/calcium chloride thermally induced emulsion gels: Rheological properties and digestive characteristics

We present the preparation and physicochemical properties of thermally induced emulsion gels of a soy protein isolate-whey protein isolate (SPI-WPI)/calcium chloride composite, and the analysis of their nutrient release behaviors using fat-soluble vitamin E as a model system by simulating its digestion in vitro. In general, the SPI-WPI composite emulsion gel was found to have better water-holding capacity and texture than the emulsion gels formed by the single protein. The microstructure and rheological properties of the gel suggested that the CaCl₂ concentration significantly influences the fundamental structure and mechanical properties of the SPI-WPI gel. The in vitro digestion experiments revealed that the mixed protein emulsion gel improves the bioavailability of vitamin E. This study is of great significance in the utilization of these natural emulsifiers, as they can be used in the development of emulsion delivery systems for lipophilic nutrients and other health products.

New Insights into Cheese Microstructure

Microscopy is often used to assist the development of cheese products, but manufacturers can benefit from a much broader application of these techniques to assess structure formation during processing and structural changes during storage. Microscopy can be used to benchmark processes, optimize process variables, and identify critical control points for process control. Microscopy can also assist the reverse engineering of desired product properties and help troubleshoot production problems to improve cheese quality. This approach can be extended using quantitative analysis, which enables further comparisons between structural features and functional measures used within industry, such as cheese meltability, shreddability, and stretchability, potentially allowing prediction and control of these properties. This review covers advances in the analysis of cheese microstructure, including new techniques, and outlines how these can be applied to understand and improve cheese manufacture.

Altering almond protein function through partial enzymatic hydrolysis for creating gel structures in acidic environment

Protein inadequacy is the major problem for most plant-based dairy yoghurt substitutes. This study investigated three limited degree of hydrolysis (DH: 1%, 5%, and 9%) of almond protein and the combined effect of DH and hydrolysed almond protein (HP) to non-hydrolysed almond protein (NP) ratios (HP/NP: 40:60, 20:80, 10:90 and 5:95) on the physicochemical properties of resulting fermentation induced almond-based gel (yoghurt). The gel microstructure, particle size, firmness, pH, water holding capacity (WHC), lubrication, flow, and gelation characteristics were measured and associated with the DH, composition, and SDS-PAGE results. The results show significant differences in gel samples with the same HP/NP (40:60) ratio of protein but different protein DH. A higher DH (9%) resulted in samples with lower hardness (6.03 g), viscosity (0.11 Pa s at 50 s-1), cohesiveness (0.63) and higher friction (0.203 at 10 mm/s) compared to sample with 1% DH with higher hardness - 7.34 g, viscosity at 50 s⁻¹ - 0.16 Pa s, cohesiveness - 0.86 and friction at 10 mm/s - 0.194. Comparing samples with the same DH (5%) but different HP/NP ratios showed smaller coarse microgel particles (21.36 μm) and lower hardness (7.17 g), viscosity (0.14 Pa s at 50 s⁻¹) and friction value (0.189 at 10 mm/s) in samples with high HP/NP (40:60) compared to sample with low HP/NP (5:95) that contained significantly large coarse microgel particles (34.61 μm) with the gel being very hard (9.38 g), highly viscous (0.32 Pa s at 50 s⁻¹), and less lubricating (0.220 at 10 mm/s).

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Enzymatic treatment changes the almond protein profile.

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Increased the degree of hydrolysis weakens the gel strength.

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The more hydrolysed protein used in formulation the softer the gel.

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Limited hydrolysis may contribute to bacterial metabolism.

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The microstructure verifies the improvement of gel's water holding capacity.

Gastric digestion of cow milk, almond milk and oat milk in rats

In this study, gastric digestion of isocaloric and iso-macronutrient cow milk, almond milk and oat milk were compared in rats euthanized at different post-feeding times.

Composition of Brazil Nut (Bertholletia excels HBK), Its Beverage and By-Products: A Healthy Food and Potential Source of Ingredients

The consumption of plant-based beverages is a growing trend and, consequently, the search for alternative plant sources, the improvement of beverage quality and the use of their by-products, acquire great interest. Thus, the purpose of this work was to characterize the composition (nutrients, phytochemicals and antioxidant activity) of the Brazil nut (BN), its whole beverage (WBM), water-soluble beverage (BM-S), and its by-products of the beverage production: cake, sediment fraction (BM-D), and fat fraction (BM-F). In this study, advanced methodologies for the analysis of the components were employed to assess HPLC-ESI-QTOF (phenolic compounds), GC (fatty acids), and MALDI-TOF/TOF (proteins and peptides). The production of WBM was based on a hot water extraction process, and the production of BM-S includes an additional centrifugation step. The BN showed an interesting nutritional quality and outstanding content of unsaturated fatty acids. The investigation found the following in the composition of the BN: phenolic compounds (mainly flavan-3-ols as Catechin (and glycosides or derivatives), Epicatechin (and glycosides or derivatives), Quercetin and Myricetin-3-O-rhamnoside, hydroxybenzoic acids as Gallic acid (and derivatives), 4-hydroxybenzoic acid, ellagic acid, Vanillic acid, p-Coumaric acid and Ferulic acid, bioactive minor lipid components (β-Sitosterol, γ-Tocopherol, α-Tocopherol and squalene), and a high level of selenium. In beverages, WBM had a higher lipid content than BM-S, a factor that influenced the energy characteristics and the content of bioactive minor lipid components. The level of phenolic compounds and selenium were outstanding in both beverages. Hydrothermal processing can promote some lipolysis, with an increase in free fatty acids and monoglycerides content. In by-products, the BM-F stood out due to its bioactive minor lipid components, the BM-D showed a highlight in protein and mineral contents, and the cake retained important nutrients and phytochemicals from the BN. In general, the BN and its beverages are healthy foods, and its by-products could be used to obtain healthy ingredients with appreciable biological activities (such as antioxidant activity).

Applicable Plant Proteins and Dietary Fibers for Simulate Plant-Based Yogurts

Effects of plant proteins and dietary fibers on the physical properties of stirred soy yogurt were investigated. Buffering capacity against lactic acid was not affected by the protein concentration for any of the four proteins that were examined: isolate soy protein (ISP), pea protein (PP), rice protein (RP), and almond protein (AP). Three proteins other than AP exhibited an increase in buffering capacity (dB/dPH) following a physical treatment, whereas AP saw a decrease in buffering capacity. Furthermore, physically treated PP revealed a significant increase in viscosity, reaching up to 497 cp in the pH 6.0~6.2 range during the titration process. Following fermentation, PP produced the highest viscosity and coagulum strength with no syneresis. In the case of dietary fiber, Acacia Fiber (AF) was completely dissolved in the solvent and did not affect the physical properties of the fermented coagulum. Soy fiber (SF) was also not suitable for fermented milk processes because precipitation occurred after the physical treatment. In the case of citrus fiber (CF), however, syneresis did not occur during storage after the physical treatment, and the viscosity also increased up to 2873 cP. Consequently, PP and CF were deemed to be a suitable plant protein and dietary fiber for stirred soy yogurt, respectively.

Physicochemical and microstructural properties of fermentation-induced almond emulsion-filled gels with varying concentrations of protein, fat and sugar contents

The influence of the protein, fat and sugar in almond milk on the formation of the acidic gel was investigated by determining their physicochemical and microstructural properties. The protein, fat and sugar in the almond milk were varied from 2% to 6%, 0.8%-7% and 0.6%-7%, respectively and fermented using Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiles cultures to form a gel structure. Both protein and fat increased the gel strength, viscosity (stirred gel) and lightness of almond yoghurts as the concentration increased. The addition of protein content increased the cohesiveness (from 0.70 to 1.17), water holding capacity (from 28.75% to 52.22%) and D_4,3 value of particle size (from 32.76 μm to 44.41 μm) of almond yoghurt. Fat reduction decreased the firmness (from 6.56 g to 4.69 g), D_4,3 value (from 88.53 μm to 18.37 μm), and water holding capacity (from 48.96% to 27.66%) of almond yoghurt. With sugar addition, almond yoghurt showed increased adhesiveness, decreased lightness and a low pH, with no significant difference in firmness, particle size, and flow behaviour. The confocal images provided evidence that the fortified protein contents homogeneously entrapped fat globules resulting in a more stable gel network and increased fat content led to large fat globule formation resulting in a harder gel network, while the added sugar did not significantly affect the gel network. The results suggested that the protein fortification enhances the texture of almond yoghurt. The fat content of 7% with 3.5% protein showed poor consistency and gel strength of yoghurt. Sugar mainly contributed to bacterial metabolism during fermentation.

Functionality of Ingredients and Additives in Plant-Based Meat Analogues

Meat analogue research and development focuses on the production of sustainable products that recreate conventional meat in its physical sensations (texture, appearance, taste, etc.) and nutritional aspects. Minced products, like burger patties and nuggets, muscle-type products, like chicken or steak-like cuts, and emulsion products, like Frankfurter and Mortadella type sausages, are the major categories of meat analogues. In this review, we discuss key ingredients for the production of these novel products, with special focus on protein sources, and underline the importance of ingredient functionality. Our observation is that structuring processes are optimized based on ingredients that were not originally designed for meat analogues applications. Therefore, mixing and blending different plant materials to obtain superior functionality is for now the common practice. We observed though that an alternative approach towards the use of ingredients such as flours, is gaining more interest. The emphasis, in this case, is on functionality towards use in meat analogues, rather than classical functionality such as purity and solubility. Another trend is the exploration of novel protein sources such as seaweed, algae and proteins produced via fermentation (cellular agriculture).

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.