Almond Protein Research Articles

Improvement of the production of pequi almond (Caryocar brasiliense Camb.) protein hydrolysates through ultrasound-assisted enzymolysis: Impact on hydrolysis kinetics, structure and functional properties of hydrolysates

This study investigated the kinetics of ultrasound (US)-assisted hydrolysis of pequi almond protein (PAP) and the conformational and multifunctional characteristics of the hydrolysates. The US-assisted enzymolysis of PAP using Alcalase® was conducted in a US bath (25 kHz, 38 W/L) for 180 min at 60 °C and pH 7.5. The results showed an increase in the rate of proteolysis by 11.3 %, leading to a higher final degree of hydrolysis (25.2 %) and a greater concentration of TCA-soluble proteins after 45 min and 180 min (29 % and 8 %, respectively). Both conventional and US-assisted hydrolysis led to the breakdown of the protein structure, forming low molecular weight peptides (<15 kDa). However, US-assisted hydrolysis demonstrated greater fragmentation of the PAP surface, enhancing enzymatic efficacy. Intrinsic fluorescence and UV spectroscopy indicated increased exposure of hydrophobic groups throughout hydrolysis, and FTIR spectroscopy revealed changes in the amide bands, suggesting structural transitions in the protein. Finally, the hydrolysates obtained from the USassisted reaction showed higher solubility (≤27 % at pH 6.0), foaming capacity (≤82 % at pH 6.0), and antioxidant activity (≤40 %). Therefore, these results indicate the potential of the US to improve the performance of Alcalase® in the hydrolysis of PAP, producing compounds of industrial interest.

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.

Enhancing Functional Properties and Protein Structure of Almond Protein Isolate Using High-Power Ultrasound Treatment.

The suitability of a given protein for use in food products depends heavily on characteristics such as foaming capacity, emulsifiability, and solubility, all of which are affected by the protein structure. Notably, protein structure, and thus characteristics related to food applications, can be altered by treatment with high-power ultrasound (HUS). Almonds are a promising source of high-quality vegetable protein for food products, but their physicochemical and functional properties remain largely unexplored, limiting their current applications in foods. Here, we tested the use of HUS on almond protein isolate (API) to determine the effects of this treatment on API functional properties. Aqueous almond protein suspensions were sonicated at varying power levels (200, 400, or 600 W) for two durations (15 or 30 min). The molecular structure, protein microstructure, solubility, and emulsifying and foaming properties of the resulting samples were then measured. The results showed that HUS treatment did not break API covalent bonds, but there were notable changes in the secondary protein structure composition, with the treated proteins showing a decrease in α-helices and β-turns, and an increase in random coil structures as the result of protein unfolding. HUS treatment also increased the number of surface free sulfhydryl groups and decreased the intrinsic fluorescence intensity, indicating that the treatment also led to alterations in the tertiary protein structures. The particle size in aqueous suspensions was decreased in treated samples, indicating that HUS caused the dissociation of API aggregates. Finally, treated samples showed increased water solubility, emulsifying activity, emulsifying stability, foaming capacity, and foaming stability. This study demonstrated that HUS altered key physicochemical characteristics of API, improving critical functional properties including solubility and foaming and emulsifying capacities. This study also validated HUS as a safe and environmentally responsible tool for enhancing desirable functional characteristics of almond proteins, promoting their use in the food industry as a high-quality plant-based protein.

Nutritional Evaluation of Almond Protein-Whey Protein Double System and Its Effect on Lipid Metabolism in HepG2 Cells

Almond protein (AP) and whey protein (WP) as single animal and plant proteins have certain limitations in nutrition, but the AP-WP dual protein can play a role in nutritional complementarity, and have a certain regulatory effect on lipid metabolism. This study investigated the amino acid composition of AP-WP system and its effect on FFA induced lipid metabolism in HepG2 cells. Results showed that, using the FAO/WHO model and whole egg protein model as reference values for essential amino acid content, the optimal mixing ratio of AP-WP was determined to be 3:5. The amino acid ratio coefficient scores under this ratio were 74.20 and 81.57 for the two models respectively. Additionally, this ratio of AP-WP showed the best antioxidant activity. The FT-IR spectroscopy indicated that there is interaction between AP and WP. The study found that AP-WP improved oxidative stress and lipid accumulation in HepG2 cells by reducing ROS and TG levels. Western blot analysis showed that AP-WP inhibits the expression of SREBP-1, FAS, and ACC, regulating lipid metabolism in HepG2 cells and leading to a certain lipid-lowering effect. The combination of almond protein and whey protein can improve the nutritional value of food and give full play to the physiological regulation of different proteins to promote human health. The research aims to lay the theoretical foundation for the application of double-protein system in the fields of nutritional food processing and lipid metabolism regulation.

Enhancing plant-based cheese formulation through molecular docking and dynamic simulation of tocopherol and retinol complexes with zein, soy and almond proteins via SVM-machine learning integration

The current study addresses the growing demand for sustainable plant-based cheese alternatives by employing molecular docking and deep learning algorithms to optimize protein-ligand interactions. Focusing on key proteins (zein, soy, and almond protein) along with tocopherol and retinol, the goal was to improve texture, nutritional value, and flavor characteristics via dynamic simulations. The findings demonstrated that the docking analysis presented high accuracy in predicting conformational changes. Flexible docking algorithms provided insights into dynamic interactions, while analysis of energetics revealed variations in binding strengths. Tocopherol exhibited stronger affinity (−5.8Kcal/mol) to zein compared to retinol (−4.1Kcal/mol). Molecular dynamics simulations offered comprehensive insights into stability and behavior over time. The integration of machine learning algorithms improved the classification and the prediction accuracy, achieving a rate of 71.59%. This study underscores the significance of molecular understanding in driving innovation in the plant-based cheese industry, facilitating the development of sustainable alternatives to traditional dairy products.

High-pressure microfluidisation positively impacts structural properties and improves functional characteristics of almond proteins obtained from almond meal

Almond protein isolate (API) obtained from almond meal was processed using dynamic high-pressure microfluidisation (0, 40, 80, 120, and 160 MPa pressure; single pass). Microfluidisation caused significant reductions in the particle size and increased absolute zeta potential. SDS-PAGE analysis indicated reduction in band intensity and the complete disappearance of bands beyond 80 MPa. Structural analysis (by circular dichroism, UV–Vis, and intrinsic-fluorescence spectra) of the API revealed disaggregation (up to 80 MPa) and then re-aggregation beyond 80 MPa. Significant increments in protein digestibility (1.16-fold) and the protein digestibility corrected amino acid score (PDCAAS; 1.15-fold) were observed for the API (80 MPa) than control. Furthermore, significant improvements (P < 0.05) in the functional properties were observed, viz., the antioxidant activity, protein solubility, and emulsifying properties. Overall, the results revealed that moderate microfluidisation treatment (80 MPa) is an effective and sustainable technique for enhancing physico-chemical and functional attributes of API, thus potentially enabling its functional food/nutraceuticals application.

Protein hydrolysates prepared by Alcalase using ultrasound and microwave pretreated almond meal and their characterization.

The study aimed to optimize ultrasonic (US: 40kHz/200W for 10, 20, 30, 40, and 50min), and microwave (MW: 160W for 45, 90, 125, 180, and 225s) pretreatment conditions on protein extraction yield and degree of protein hydrolysis (DH) from almond de-oiled meal, an industrial by-product. First order model was used to describe the kinetics of almond protein hydrolysates obtained with Alcalase. The highest DH, 10.95% was recorded for the US-50min and 8.87% for MW-45s; while it was 5.76% for the untreated/control sample. At these optimized pretreatment conditions, a 1.16- and 1.18-fold increment in protein recovery was observed for theUS and MW pretreatments, respectively in comparison to the conventional alkaline extraction. The molecular weight distribution recorded for pretreated samples disclosed a significant reduction in the band thickness in comparison with control. Both the pretreatments resulted in a significant increase (P < 0.05) in the antioxidant activity, and TCA solubility index when compared with the control. Results evinced that US and/or MW pretreatments before enzymatic hydrolysis can be a promising approach for the valorization of almond meal for its subsequent useas an ingredient for functional foods/nutraceuticals which otherwise fetches low value as an animal feed.

The rheological, textural, frictional, and digestive properties of starch-based cheese analogs prepared with tapioca starch and almond protein

Abstract Most commercial starch-based cheese analogs were pointed out that protein content is low, but protein can affect the formation of the starch gel and its sensory properties. Almond proteins have high nutritional values because they are abundant in essential amino acids. In this study, the effects of different tapioca starch/almond protein proportions on the starch-based cheese analogs texture, rheology, friction and digestion properties were studied. The addition of almond protein to starch-based cheese analogs resulted in soft texture, small storage modulus values, increased friction coefficients, and increased fat digestibility as the proportion of protein increased. When increase the starch proportion, an opposite trend was observed. These findings showed that protein-supplemented starch-based cheese analogs with tunable texture, rheological, frictional and digestive properties can be easily produced by controlling the proportion of tapioca starch/almond protein.

First biosensing platform for detecting traces of almonds in processed foods by electrochemical determination of the allergenic protein Pru du 6

A novel electrochemical bioplatform for Pru du 6determination, one of the most abundant and allergenic almond proteins, was developed to detect traces of almonds in processed foods. The bioplatform combines the application of a sandwich immunoassay on the surface of magnetic beads using specific antibodies unmodified or conjugated to horseradish peroxidase as capture and detection antibodies. The resulting magnetic bioconjugates are trapped on the surface of disposable carbon electrodes, and amperometry in the presence of hydrogen peroxide and hydroquinone is employed to measure the change in the cathodic current, which is proportional to Pru du 6 concentration. The developed bioplatform exhibited good selectivity and sensitivity, offering a detection limit of 0.12 ng mL−1 of Pru du 6. It could determine Pru du 6 in raw dough and baked cookies incurred with 0.2 µg g−1 of almond protein with acceptable precision, providing results comparable to those obtained using an ELISA technique.

Identification of potential antioxidant peptides from protein hydrolysates of pearl oil apricot almonds: Combination of in vitro and molecular docking studies

AbstractPearl oil apricot almonds are rich in proteins, being a valuable raw material for preparing antioxidant peptides. In this study, almond protein hydrolysates (APHs) were obtained by enzymatic hydrolysis and divided into APHs‐1 (&lt;3 kDa), APHs‐2 (3–10 kDa), and APHs‐3 (&gt;10 kDa). APHs‐1‐c, purified from APHs‐1, was proved to show the strongest antioxidant effect through activity tracking experiments. APHs‐1‐c also can protect HepG2 cells against oxidative damage by reducing intracellular reactive oxygen species and MDA levels, elevating glutathione levels as well as increasing superoxide dismutase and catalase activities, and its protective effect is related to the Keap1–Nrf2 signaling pathway. Forty bioactive peptide sequences were identified from APHs‐1‐c, and Thr‐Glu‐Asp‐Asp‐Trp‐Arg‐Trp‐His (TEDDWRWH; P1), Trp‐Tyr‐Asp‐Asn‐Glu‐Trp‐Gly‐Tyr‐Arg (WYDNEWGYR; P2), and Ala‐Glu‐Asp‐His‐Glu‐Trp‐Trp‐Arg (AEDHEWWWR; P3) had the most potential for antioxidant activity by molecular docking studies. P1, P2, and P3 showed desirable 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity (IC50 = 0.634–3.381 mmol/L), 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt radical scavenging activity (IC50 = 0.221–0.309 mmol/L), and ferric‐reducing antioxidant power. These results suggested that almonds protein hydrolysates and its derived antioxidant peptides could serve as potential ingredients applied in functional foods.

Production and features of antioxidative hydrolysate from wild almond protein isolate using ficin immobilised on the layered double hydroxide

SummaryProtein hydrolysates from wild almond protein isolate (WAPI) with different degrees of hydrolysis (DH) were synthesised using free and immobilised ficin on the magnetic layered double hydroxide and characterised. The highest DH values after 3 h of achieving 11.69 ± 0.15 and 11.37 ± 0.12, respectively, and gained hydrolysate were collected for further analysis. The zeta potential for the hydrolysis of free and immobilised ficin over hydrolysing time due to differences in molecular mass distribution decreased. By increasing the hydrolysing time in the case of free and immobilised ficin, the emulsion activity index gradually decreased, whereas the amount of emulsion stability index did not. The immobilised form of ficin‐treated hydrolysate showed a suitable level of DPPH radical scavenging and appeared to be effective in enhancing the oxidative stability of linoleic acid, sunflower oil and O/W emulsion. Thus WAPI hydrolysates that were treated with immobilised ficin could serve as an alternative antioxidant for food applications.

Effects of protease-assisted aqueous extraction on almond protein profile, digestibility, and antigenicity

Almonds (Prunus dulcis) are one of the most consumed tree nuts worldwide and have been recognized as a healthy and nutritious food. Nevertheless, almonds are also a source of allergenic proteins that can trigger several mild to life-threatening allergic reactions. The effects of selected extraction conditions (aqueous vs. protease-assisted aqueous extraction) on the protein profile determined by proteomics analysis of excised SDS-PAGE gel bands, in vitro protein digestibility, and immunoreactivity of almond protein extracts, were evaluated. Proteolysis altered almond protein sequential and conformational characteristics thus affecting digestibility and antigenicity. Proteomics analysis revealed that enzymatic extraction resulted in the reduction of allergen proteins and epitopes. While complete hydrolysis of Prunin 1 and 2 α-chain was observed, Prunin 1 and 2 β-chains were more resistant to hydrolysis. Protein in vitro digestibility increased from 79.1 to 88.5% after proteolysis, as determined by a static digestion model. The degree of hydrolysis (DH) and peptide content of enzymatically extracted proteins during gastric and duodenal digestion were significantly higher than the ones from unhydrolyzed proteins. Proteolysis resulted in a 75% reduction in almond protein immunoreactivity as determined by a sandwich enzyme-linked immunosorbent assay and a reduction in IgE and IgG reactivities using human sera. The present study shows that moderated hydrolysis (7% DH) using protease can be used as a strategy to improve almond protein digestibility and reduce antigenicity. This study's findings could further enhance the potential use of almond protein hydrolysates in the formulation of hypoallergenic food products with improved nutritional quality and safety.

Development of a simple and reliable LC-MS/MS method to simultaneously detect walnut and almond as specified in food allergen labelling regulations in processed foods

We developed a simple and reliable analytical method using high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) to simultaneously detect walnut and almond as specified in regulations for food allergen labelling in processed foods. Five specific target peptides derived from walnut 2S albumin and 7S globulin and three target peptides from almond 11S globulin were selected by analysing several varieties of walnut and almond, eight kinds of other nuts, and ten kinds of major allergen ingredients or cereals. The limit of detection for the walnut 2S albumin peptide GEEMEEMVQSAR (m/z 698.3 [precursor] > 316.1 [product]) was 0.22 ± 0.02 μg/g, and that for almond 11S globulin peptide GNLDFVQPPR (m/z 571.8 [precursor] > 369.2 [product]) was 0.08 ± 0.02 μg/g when extracted walnut and almond protein were spiked into butter cookie chocolate ice cream. These peptides had good linearity (R2 > 0.999) for each calibration curve with a range of 0.1–50 μg/mL protein concentration in the sample solutions, and sufficient recovery rates (90.4–101.5%) from the spiked samples. The developed analytical approach is applicable to a wide variety of processed foods for food allergen labelling.

Improving the functional properties of wild almond protein isolate films by Persian gum and cold plasma treatment

The application of edible films in food packaging is limited due to their poor functional properties. Cold plasma treatment (CPT) is an emerging technology for the modification of edible films. In this study, edible films were developed from different ratios of wild almond protein isolate (WAPI) and Persian gum (PG). The characterization of films revealed that the sample containing 90 % WAPI and 10 % PG had the highest elongation at break (E), the highest tensile strength (TS), and the lowest water vapor permeability (WVP). Therefore, it was selected as having the best WAPI:PG ratio and exposed to CPT for 5, 10, and 15 min. The results revealed that the application of CPT significantly increased the thickness, TS, and E of edible films, while WVP and solubility were not affected. FTIR spectra showed slight increases in peak intensities at 1628, 1538, and 1400 cm−1. The micrographs revealed that the roughness of composite films increased with increased cold plasma treatment time. In general, edible films treated by CPT for 10 min demonstrated the best functional properties.

Peripheral Amino Acid Appearance Is Lower Following Plant Protein Fibre Products, Compared to Whey Protein and Fibre Ingestion, in Healthy Older Adults despite Optimised Amino Acid Profile.

Plant-based proteins are generally characterised by lower Indispensable Amino Acid (IAA) content, digestibility, and anabolic properties, compared to animal-based proteins. However, they are environmentally friendlier, and wider consumption is advocated. Older adults have higher dietary protein needs to prevent sarcopenia, a disease marked by an accelerated loss of muscle mass and function. Given the lower environmental footprint of plant-based proteins and the importance of optimising dietary protein quality among older adults, this paper aims to assess the net peripheral Amino Acid (AA) appearance after ingestion of three different plant protein and fibre (PPF) products, compared to whey protein with added fibre (WPF), in healthy older adults. In a randomised, single-blind, crossover design, nine healthy men and women aged ≥65 years consumed four test meals balanced in AA according to the FAO reference protein for humans, matched for leucine, to optimally stimulate muscle protein synthesis in older adults. A fasted blood sample was drawn at each visit before consuming the test meal, followed by postprandial arterialise blood sampling every 30 min for 3 h. The test meal was composed of a soup containing either WPF or PPF 1-3. The PPF blends comprised pea proteins with varying additional rice, pumpkin, soy, oat, and/or almond protein. PPF product ingestion resulted in a lower maximal increase of postprandial leucine concentration and the sum of branched-chain AA (BCAA) and IAA concentrations, compared to WPF, with no effect on their incremental area under the curve. Plasma methionine and cysteine, and to a lesser extent threonine, appearance were limited after consuming the PPF products, but not WPF. Despite equal leucine doses, the WPF induced greater postprandial insulin concentrations than the PPF products. In conclusion, the postprandial appearance of AA is highly dependent on the protein source in older adults, despite providing equivalent IAA levels and dietary fibre. Coupled with lower insulin concentrations, this could imply less anabolic potential. Further investigation is required to understand the applicability of plant-based proteins in healthy older adults.

Administration of Alphitobius diaperinus or Tenebrio molitor before meals transiently increases food intake through enterohormone regulation in female rats.

It has been previously shown that acutely administered insect Alphitobius diaperinus protein increases food intake in rats and modifies the ex vivo enterohormone secretory profile differently than beef or almond proteins. In this study, we aimed to evaluate whether these effects could be maintained for a longer period and determine the underlying mechanisms. We administered two different insect species to rats for 26 days and measured food intake at different time points. Both insect species increased food intake in the first week, but the effect was later lost. Glucagon-like peptide 1 (GLP-1) and ghrelin were measured in plasma and ex vivo, and no chronic effects on their secretion or desensitization were found. Nevertheless, digested A. diaperinus acutely modified GLP-1 and ghrelin secretion ex vivo. Our results suggest that increases in food intake could be explained by a local ghrelin reduction acting in the small intestine. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Investigating the functionality of enzymatically (transglutaminase and alcalase) treated almond protein isolate

The effects of partial hydrolysis on the functional properties of almond protein isolate (API) were investigated by treating the isolate with alcalase enzyme (2.4U/g) and a subsequent polymerization of API was studied using the enzyme, transglutaminase (121U/g). The result obtained showed that partial hydrolysis could induce structural changes in almond protein, mainly reflecting at the molecular weight, duration of hydrolysis, and the active site of the enzymes. On comparing the two enzymes' ability to react on API, enzyme alcalase resulted in producing hydrolysates with the highest protein solubility of 89.38%, surface hydrophobicity of 62.68, and foaming expansion of 31% at the 60th minute of hydrolysis and produced lower molecular weight peptides. Although alcalase API hydrolysates improved the protein's functionality, the enzyme failed to increase the substrate's emulsion and foaming stabilities. On the other hand, transglutaminase enzyme produced higher molecular weight peptides and excelled in enhancing the stability of emulsion and foam along with the elevation of %degree of hydrolysis.

Adsorption of Quercetin on Brown Rice and Almond Protein Matrices: Effect of Quercetin Concentration.

Plant-based proteins are very often used as carriers of different phenolic compounds. For that purpose, complexation of quercetin with almond and brown rice protein matrices was investigated. The amount of protein matrices was constant, while the concentration of quercetin varied (1 mM, 2 mM or 5 mM) during complexation. Dried complexes were investigated for quercetin amount (HPLC analysis) and antioxidant activity (DPPH, FRAP and CUPRAC methods). Additionally, complexation was proven by DSC and FTIR-ATR screening. An increase in the concentration of quercetin in the initial complexation mixture resulted in the increase in the adsorption of quercetin onto protein matrices. For the brown rice protein matrices, this increase was proportional to the initial quercetin concentration. Adsorption of quercetin caused the change in thermal stability of microparticles in comparison to corresponding protein matrices that have been proven by DSC. FTIR-ATR analysis revealed structural changes on microparticles upon adsorption of quercetin.

Understanding the impact of enzyme-assisted aqueous extraction on the structural, physicochemical, and functional properties of protein extracts from full-fat almond flour

The need for sustainable protein sources has prompted research on several plant-based protein matrices. The effects of enzymatic extraction on the composition, physicochemical, structural, and functional properties of protein-extracts (skim) from full-fat almond flour were elucidated. Protein-extracts were produced by aqueous (AEP), and enzyme-assisted extraction processes (EAEP), which enable concurrent extraction and fractionation of lipids and proteins without the use of flammable solvents. Except for the use of 0.5% of protease in the EAEP, extraction parameters were similar for both processes (pH 9.0, 50 °C, 1:10 solids-to-liquid ratio, and 60 min). The use of enzyme to assist the extraction resulted in the production of protein extracts with higher protein content and promoted the formation of smaller peptides and a more unordered protein secondary structure with reduced surface hydrophobicity. These structural modifications reduced the EAEP skim protein thermostability and improved its water absorption capacity (2.4 vs. 2.7 g water/g protein) compared with the AEP proteins. Importantly, proteolysis significantly enhanced the functionality of the hydrolysates at pH values close to the almond protein isoelectric point. At pH 5.0, EAEP skim proteins had higher solubility (47 vs 23%), emulsification capacity (492 vs 402 g oil/g protein), emulsification activity index (35 vs 17 m2/g) and foaming capacity (23 vs 11%) compared with AEP proteins. These results indicate that moderate hydrolysis can be used to improve extractability and the functionality of almond proteins, creating new opportunities for its application as food ingredients.

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).