Pea Protein Concentrate Research Articles

Exploring the oil-water interfacial behaviour of pea protein-guar gum/gellan gum mixtures relating to stability and in vitro protein digestion of model pea milk system

Polysaccharides are effective stabilisers for plant-based milks, but their interfacial adsorption behaviours in plant milk system and effects on plant protein digestibility are still unclear. This study analysed the oil-water interfacial adsorption behaviours of pea protein concentrate (PPC) and isolate (PPI) mixed with neutral guar gum and anionic gellan gum to understand the stability and in vitro protein digestion of corresponding model pea milk system. Adding guar gum or gellan gum enhanced the interfacial adsorption stability of pea proteins without compromising proteolysis during gastrointestinal digestion. Gellan gum performed better than guar gum for long-term co-stabilising the emulsion with pea proteins, due to its electrostatic repulsion with pea proteins and stronger steric hindrance induced by thicker adsorbed interfacial layers (~10 % or ~37 % higher thickness than guar gum counterparts) as detected by a quartz crystal microbalance with dissipation (QCM-D) after rinsing. The model pea milks with 0.1 % (wt%) gellan gum were stable at 4 °C for 28 days regardless of protein types. The presence of polysaccharides at the interface enabled oil droplets to be kept separate during in vitro gastrointestinal digestion, improving the final proteolysis by ~4 to ~27 %. This result is conducive to selecting polysaccharides for developing pea protein-based beverages.

Probiotic Milk Enriched with Protein Isolates: Physicochemical, Organoleptic, and Microbiological Properties.

Incorporating plant protein isolates into milk can enhance probiotic culture growth by providing essential nutrients and altering the physicochemical properties of fermented milk. This study investigated the effects of adding 1.5% or 3.0% soy, pea, and whey protein isolates on the growth of Lacticaseibacillus casei and Lactobacillus johnsonii monocultures, as well as the physicochemical (acidity, syneresis, color) and organoleptic properties of fermented milk during 21 days of refrigerated storage. The results showed that 1.5% SPI and WPI did not significantly alter milk acidity compared to controls. Still, pH increased with 1.5% and 3.0% PPI. Storage time significantly affected pH in L. casei fermented milk. The initial addition of WPI at 1.5% and 3.0% reduced syneresis in L. casei fermented milk compared to other samples. Color components were significantly influenced by isolates. Initial L. casei cell counts were lower with SPI (LCS1.5 and LCS3) and 1.5% PPI (LCP1.5) compared to controls. Increasing isolate concentration from 1.5% to 3% enhanced L. johnsonii growth in WPI-milk but reduced L. casei in LCW3 compared to LCW1.5. Only increased pea protein concentration significantly increased L. casei growth. Probiotic populations generally were reduced during extended storage. Moreover, isolates impacted milk organoleptic evaluation. This research demonstrates the potential of protein isolates in creating health-promoting and diverse fermented products and offers insights into their interaction with probiotic cultures to advance functional food technologies.

Understanding Stabilization of Oil-in-Water Emulsions with Pea Protein─Studies of Structure and Properties.

This study investigates the stability and structure of oil-in-water emulsions stabilized by pea protein. Of the wide range of emulsion compositions explored, a region of stability at a minimum of 5% w/v pea protein and 30-50% v/v oil was determined. This pea protein concentration is more than what is needed to form a layer covering the interface. X-ray scattering revealed a thick, dense protein layer at the interface as well as hydrated protein dispersed in the continuous phase. Shear-thinning behavior was observed, and the high viscosity in combination with the thick protein layer at the interface creates a good stability against creaming and coalescence. Emulsions in a pH range from acidic to neutral were studied, and the overall stability was observed to be broadly similar independently of pH. Size measurements revealed polydisperse protein particles. The emulsion droplets are also very polydisperse. Apart from understanding pea protein-stabilized emulsions in particular, insights are gained about protein stabilization in general. Knowledge of the location and the role of the different components in the pea protein material suggests that properties such as viscosity and stability can be tailored for various applications, including food and nutraceutical products.

Development of Sustainable Vegan Pea Protein-Zinc Complex: Characterization, In Vitro Cellular Mineral Uptake, and Application in Functional Biscuit Production

This study aimed to investigate the potential of pea protein concentrate (PPC) to form protein-mineral composites, with a specific focus on its zinc- (Zn-) binding capabilities. In addition, the physical and functional properties of PPC were evaluated. PPC, a potential protein source, was found to possess lipophilic properties, suggesting its suitability for various applications in food production. The investigation involved a comprehensive characterization of pea protein concentrate-zinc complex (PPC-Zn) composites, utilizing various analytical techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, particle size analysis, zeta potential measurement, and thermogravimetric analysis. The findings of this study indicated that the protein content of PPC-Zn (79.02 ± 1.33%) insignificantly increased as compared to PPC (78.86 ± 1.16%). Furthermore, PPC demonstrated improved functional properties, including increased protein solubility (2.55%), enhanced water-holding (13.09%) and oil-holding capacity (11.17%), and improved foaming capacity and stability (2.08% and 6.07%, respectively). These improvements in functional properties were likely attributed to the unique surface structure observed in SEM micrographs. The research also highlighted the maximum binding capacity of PPC for zinc, which was observed at concentrations of 5 mM (95.35 ± 1.86%). This binding of zinc ions to PPC induced changes in the characteristics and internal structures of the protein concentrate. Notably, the presence of functional groups such as -COOH, -OH, and –NH2 in PPC suggested their involvement in coordinating with zinc ions to form PPC-Zn composites. This investigation demonstrated a significant increase (2.26%) in the mineral bioavailability of PPC-Zn. Additionally, the cellular uptake, retention, and transport of PPC-Zn were improved by 9.79%, 7.84%, and 9.51%, respectively. Fortified biscuits (B2) demonstrated enhanced cellular uptake (2.79%), retention (4.84%), and transport (3.51%) compared with control biscuits. Fortified biscuits (B2) had higher microbial counts (total plate count is 3.57 ± 0.03 and the yeast-mold count is 3.96 ± 0.07 cfu/g) than control biscuits (B1) (total plate count is 2.49 ± 0.13 and the yeast-mold count is 3.44 ± 0.11 cfu/g) at the end of storage, and there is no difference in sensory evaluation between the control and fortified biscuits. Furthermore, the key findings indicated that PPC could serve as a promising carrier for mineral supplements, binding with zinc effectively.

Rice bran oil-in-water optimized emulsions for the development of plant-based foods and beverages

Aim: This work aimed to develop rice bran oil-in-water (O/W) emulsions, stabilized with different mixtures of pea protein concentrate (PPC), Arabic gum (AG), and maltodextrin (MD), as the basis for the formulation of plant-based food products. Methods: The effects of the aqueous phase formulation on the properties of the resulting O/W emulsions were evaluated by a mixture design approach. Volume-weighted mean diameter (D[4,3]) of the emulsion particles and polydispersity expressed as the difference of D[4,3] – D[3,2], apparent viscosity at a shear rate of 200 s–1 and backscattering at different times associated to the global stability of the emulsions were studied as response variables. A multi-response optimization was carried out and mathematical models were validated. Results: The ternary mixtures of the aqueous phase showed significant antagonism between the three components in all the response variables. The optimal formulation of the aqueous phase for the O/W emulsions obtained after three homogenization cycles was 78% PPC and 22% MD. The properties of the O/W optimal emulsion were according to the ones predicted by the model. Conclusions: The best-formulated emulsion is promising for developing plant-based foods and beverages.

Enzymatic degradation of pea fibers changes pea protein concentrate functionality

Pea proteins are gaining increased interest from both the food industry as well as from consumers. Pea protein isolates (PPI) excel at forming meat-like textures upon heating while pea protein concentrates (PPC) are more challenging to transform into highly sought-after foods. PPCs are richer in dietary fibers (DF) and are more sustainable to produce than PPI. In this work, degradative enzymes were used to modify the functionality of PPC-water blends with a focus on texturization upon heating. Three enzyme solutions containing β-glucanases, hemicellulases, pectinases, xylanase, and cellulases were added to 65 wt% PPC blends. The effect of these enzymatic pretreatments was measured by monitoring the torque in a mixing reactor during blending, differential scanning calorimetry (DSC), high-pressure shear rheology (HPSR), and DF content and size analysis. Four endothermic peaks were detected in the DSC thermograms of PPC, namely at 63 °C, 77 °C, 105 °C and 123 °C. The first three peaks were attributed to phase transition and gelation temperatures of the starches and proteins constituting PPC. No endothermic peaks were measured for PPI blends. Enzyme solutions containing β-glucanases, hemicellulases, pectinases, and xylanases increased the endothermic energy of all peaks, hinting at an effect on the gelation properties of PPC. The same enzymes decreased the resistance to flow of PPC blends and induced a shift of the weight average molecular weight (Mw) distribution of soluble dietary fibers (SDF) towards smaller values while increasing the fraction of SDF by decreasing the insoluble dietary fiber (IDF) content. The solution containing cellulases did not change the DSC results or the viscosity of the PPC mixture, nor did it affect the IDF and SDF contents. On the other hand HPSR measurements of heated PPC samples up to 125 °C showed that all tested enzyme solutions decreased the complex viscosity of PPC-water blends to values similar to PPI-water blends. We demonstrated that degradative enzymes can enhance the functionality of less refined protein-rich ingredients based on pea and other vegetal sources. Using optimized enzyme blends for targeted applications can prove to be a key changer in the development and improvement of sustainable protein-rich foods.

Cultivar and environmental impacts on protein and mineral concentrations in peas (Pisum sativum L.)

AbstractPea (Pisum sativum L.) grain contains abundant protein, starch, and minerals. However, there are obstacles to growing peas that achieve consistently high protein and mineral concentrations. Seven pea cultivars were planted at seven locations with contrasting soils and environmental factors to evaluate the genetic and environmental effects on pea yield and quality. Correlations and principal component analyses (PCA) were performed to correlate pea grain yield and protein with mineral concentrations in pea grain and soil. Significant cultivar × location interactions were observed on pea grain yield but not on pea grain protein concentration. Some cultivars demonstrated more sensitivity to the environment than others in terms of grain yield potential and stability. The lack of a cultivar × location interaction for pea grain protein concentration indicates consistent genetic control of this quality parameter. Although there was a negative relationship between pea grain yield and protein concentration at the cultivar level at each environment, this correlation became weaker while pooling the data from all environments (site‐years) due to the confounding effect from environments. Pea grain mineral concentrations were significantly affected by cultivar and location, but location generally affected the mineral levels more than cultivar. Grain mineral nutrients, especially macronutrients, were highly correlated with soil minerals. The three distinct clusters formed in the PCA indicate mega environments that determine pea grain yield and quality, and understanding the mega environments in combination with improved soil fertility management may represent the most effective means of increasing pea grain yield, protein, and targeted mineral levels.

Rheology and 3D printing characteristics of heat-inducible pea protein-carrageenan-glycyrrhizic acid emulsions as edible inks

Protein-based emulsion gels, especially those induced by heat, have been widely used in food 3D printing. However, the rheology and texture of protein-based gels are important factors restricting 3D printing. In this study, glycyrrhizic acid (GA) was used to improve the rheology properties of pea protein (PP)-Kappa carrageenan (κCA) composite emulsion inks, and the suitability of these inks for extrusion 3D food printing was investigated. The results showed that all emulsion inks have shear thinning behavior and could be smoothly extruded during 3D printing. Herschel-Bulkley model fitting results proved that with the increase of PP concentration (from 5% to 10%), the yield stress (σ0) increased from 15.4 to 28.19 Pa, and the consistency coefficient (k) increased from 1.09 to 2.66 Pa.sn. The objects printed with 10% PP-GA0.3 inks showed excellent self-supporting capability, a smooth surface texture, and high printing accuracy. Emulsion inks had good temperature stability and could form emulsion gels following heat induction. The results of small amplitude oscillatory shear (SAOS) and large amplitude oscillatory shear (LAOS) tests confirmed that the addition of GA improved the strength of the gels. This research provides valuable insights for the advancement of food 3D printing inks.

Pressure-induced gelation of blended milk and pea protein suspensions

The pressure-induced (400 MPa for 15 min) gelation of blended skim milk (SMP) and pea protein concentrate (PPC) suspensions (15% w/w) at different ratios (SMP:PPC = 10:0, 8:2, 6:4, 5:5, 4:6, 2:8, 0:10) were studied. Blending milk and pea proteins reduced the gel strength markedly, indicating that milk and pea proteins do not interact with each other to the same extent. The secondary structure of the proteins was not significantly changed after HP treatment. The PPC dominating gels (0:10 and 2:8) had a large increase in surface hydrophobicity indicating higher exposure of hydrophobic clusters. Based on a differential solubility method it was established that the SMP dominating gels are govern mostly by electrostatic and hydrophobic interactions, while disulphide bonds, hydrogen bonds and electrostatic interactions contributed most to the PPC dominating gel networks. The weak 5:5 gel was established solely by hydrophobic interaction between milk and plant proteins. It is suggested that in the milk protein dominant gel (8:2), the milk proteins formed the primary gel structure likely filled with the pea protein secondary gel network and/or aggregates, whereas the inverse occurred in the pea protein dominant gel (2:8). Replacing milk proteins with pea proteins offers a great potential for produce innovative dairy products using high pressure processing, like for example dairy desserts with a neutral pH and textural properties similar to yogurt.

Effect of Heat Treatment on Yellow Field Pea (Pisum sativum) Protein Concentrate Coupled with Membrane Ultrafiltration on Emulsification Properties of the Isolated >50 kDa Proteins.

The aim of this paper was to determine the emulsification properties of protein aggregates obtained from heat pretreated yellow field pea protein concentrate (PPC). PPC dispersions were prepared in distilled water (adjusted to pH 3.0, 5.0, 7.0, or 9.0), heated in a water bath (100 °C) for 30 min, centrifuged and the supernatant passed first through a 30 kDa membrane and, then, the first retentate (>30 kDa) through a 50 kDa membrane. The 50 kDa membrane separation yielded a second retentate (>50 kDa proteins), which was isolated for emulsification studies. The near UV circular dichroic spectra of the protein samples showed more unfolded structures at pH 3.0 and 5.0 than at pH 7.0 and 9.0. The presence of small and spherical oil droplets of emulsions stabilized by the >50 kDa proteins at pH 3.0, 7.0, and 9.0 was confirmed by confocal laser scanning microscopy images. Emulsions stabilized at pH 7.0 and 9.0 had a narrower size distribution range than at pH 3.0 and 5.0. A narrow oil droplet size distribution range and lower interfacial protein concentrations of the emulsions stabilized by the >50 kDa proteins were observed at the corresponding pH of the heat treatment when compared to other pH values. Emulsions stabilized by the >50 kDa proteins exhibited a relatively low flocculation and coalescence index, which infers relative stability. The results from this work suggest that heat pretreatment of the PPC led to the formation of new protein aggregates, especially FT9 with enhanced emulsification properties, at some of the test conditions when compared to the unheated PPC.

Effects of ethanol washing on off-flavours removal and protein functionalities of pea protein concentrate

This study investigates the effects of treating pea protein concentrate (PPC) with hydroalcoholic solutions on off-flavour removal. Increasing ethanol concentration in the hydroalcoholic solutions from 15 to 75% (v/v) enhanced the removal of volatile compounds contributing to off-flavours such as 1-hexanol, 1-octanol, 3-hexen-1-ol, 1-nonanol and trans-2-hexenal. Differential scanning calorimetry and protein solubility studies showed that higher ethanol concentration induced more protein denaturation as evidenced by the lower enthalpy change and protein solubility of the treated PPC samples. Insoluble protein aggregates formed were hypothesized to be linked by hydrogen bonding. Hydroalcoholic washing of PPC also increased its water holding capacity but reduced oil holding capacity. Ethanol concentrations deployed in the hydroalcoholic solutions influenced gelling behaviour, where increase in PPC gel strength was observed in PPC treated with lower concentrations of ethanol, i.e., 15 and 25% (v/v). However, higher ethanol concentrations, i.e., 50 and 75% (v/v) induced higher extent of insoluble aggregates which weakened the gel network and reduced gel strength. In conclusion, PPC treated with high ethanol concentrations reduced majority of volatile compounds contributing to off-flavour, but significant protein structural changes which could influence product development performance were also observed.

Synergistic use of fermentation and extrusion processing to design plant protein-based sausages

The synergistic effect of lactic acid fermentation and high-moisture extrusion processing of pea protein on the microbiological and sensory properties of plant-based sausages was investigated. Plant-based sausages were formed by combining fermented pea protein concentrate (PPC) biomass with high-moisture extruded pea protein isolate (PPI). Pea protein concentrate (PPC) was fermented with Lactococcus lactis subsp. lactis and Lactiplantibacillus plantarum to improve the perceived structure, texture, and flavour (specifically via expression of glutamic acid which is connected to umami flavour) of plant-based sausages.The sausages were prepared by stuffing the mixture of extruded PPI and fermented PPC (addition level 70:30) inside vegetarian casings followed by steam cooking. After preparation and cooking of the sausages, a trained sensory panel evaluated the intensities of ten selected attributes defining the flavour, odour, colour, and texture. In addition, dry matter content, acidification, microbial quality, and glutamate contents were analysed.The results demonstrated that fermentation decreased the pea-like odour and improved the texture of the sausages. In addition, yeast-like odour and umami taste were observed. The study was able to demonstrate novel clean-label processing approaches by combined fermentation and extrusion to generate in-situ meat-like flavour and texture based on plant protein ingredients.

Mixtures of Modified Starch and Rice and Pea Protein Concentrate as Wall Material in the Microencapsulation of Flaxseed Oil

Flaxseed oil is rich in polyunsaturated fatty acids, and its incorporation into food formulations is limited due to its hydrophobic nature and susceptibility to oxidation. The aim of this work was to analyze the effect of wall material mixtures (modified starch Capsul® and rice and pea protein concentrate) on the efficiency of flaxseed oil encapsulation by freeze-drying, physical characterization, and determining oxidative stability. For the preparation of powders, four emulsions with an oil–wall material ratio of 1:3 were produced and characterized. The mass ratio between rice and pea proteins was fixed at 50–50%. The mass ratio of the protein-Capsul® mixtures was varied by 0–100%, 10–90%, 20–80%, and 30–70%. Based on the creaming index results, all emulsions showed good stability after 24 h of analysis. The powders showed low moisture content (<3.23%), bulk density (<0.2659 kg/kg), and packed bulk density (<0.4389 kg/kg). Encapsulation efficiency decreased with increasing protein content, ranging from 93.40% (protein-Capsul® ratio of 0–100%) to 18.26% (protein-Capsul® ratio of 30–70%). However, the best oxidative stability results (smaller increases in the peroxide index values at the end of the stability experiments) were obtained for the powders containing the highest levels of vegetable proteins (protein-Capsul® ratio of 20–80% and 30–70%, respectively).

Hydrolysis of pea protein concentrate in subcritical water media with addition of citrus pectin and citric acid

Pea protein concentrate (PPC) was hydrolyzed by subcritical water with citrus pectin or citric acid to obtain bioactive peptides and amino acids. Subcritical water at 160–240 oC and 50 bar for 10–60 min was used. The degree of hydrolysis (DH) significantly increased (p < 0.05) with increasing temperature. The highest DH (64.8%) was obtained at 220 oC/50 bar/10 min with a PPC:pectin ratio of 1:1 (w/w). The dominant peptide in the hydrolysate had molecular weight of 4.1 kDa. The main nd high hydronium and hydroxide ion concamino acids in the hydrolysates were hydrophilic amino acids (45.7 g/100 g protein at 180 oC/50 bar/10 min). The DPPH- scavenging activity of protein hydrolysates using citric acid was significantly higher (p < 0.05) than the ones obtained with pectin. The hydrolysates with pectin, on the other hand, had significantly (p < 0.05) higher ferric reducing antioxidant power than the ones obtained with citric acid which was likely due to the differences in the peptide size and composition.

Apparent digestibility coefficients of plant feed ingredients for olive flounder (Paralichthys olivaceus)

This study was designed to determine the apparent digestibility coefficients of soybean meal, soy protein concentrate (SPC), soy protein isolate (SPI), rapeseed meal (RSM), pea protein concentrate (PPC), wheat gluten meal (WGM) and wheat flour (WF) for olive flounder, Paralichthys olivaceus. A reference diet (RF) was formulated to meet the nutrient requirements of olive flounder with 1% chromic oxide (Cr2O3) as an inert indicator. Test diets were prepared to contain 70% RF and 30% of the test ingredient. Olive flounder, averaging 150 ± 8.0 g, was cultured in 400-L fiberglass tanks at a density of 25 fish per tank. Fecal collection columns were attached to each tank. Fecal samples were obtained from triplicate groups of fish for 4 weeks. Dry matter digestibility of SPC (75%) and WGM (76%) were significantly higher than the other test ingredients. Protein digestibility of SPC (85%), PPC (88%) and WGM (89%) were significantly higher than the other test ingredients, and protein digestibility of RSM (77%) and WF (76%) was lower than the other ingredients tested. Lipid digestibility of SPC (72%) and SPI (69%) were significantly higher than the other test ingredients. Energy digestibility of SPC (85%) and WGM (82%) were significantly higher than that of others tested ingredients. The availability of amino acids in WGM was generally higher than in other plant-feed ingredients. Therefore, SPC and WGM were seems to be efficient as potential protein sources for olive flounder compared to other tested ingredients. Overall, findings of the current study may assist in more efficient and economical formulation of diets using plant feed ingredients for olive flounder.

Prediction of Protein Concentration in Pea (Pisum sativum L.) Using Near-Infrared Spectroscopy (NIRS) Systems.

Breeding for increased protein concentration is a priority in field peas. Having a quick, accurate, and non-destructive protein quantification method is critical for screening breeding materials, which the near-infrared spectroscopy (NIRS) system can provide. Partial least square regression (PLSR) models to predict protein concentration were developed and compared for DA7250 and FT9700 NIRS systems. The reference protein data were accurate and exhibited a wider range of variation (15.3-29.8%). Spectral pre-treatments had no clear advantage over analyses based on raw spectral data. Due to the large number of samples used in this study, prediction accuracies remained similar across calibration sizes. The final PLSR models for the DA7250 and FT9700 systems required 10 and 13 latent variables, respectively, and performed well and were comparable (R2 = 0.72, RMSE = 1.22, and bias = 0.003 for DA7250; R2 = 0.79, RMSE = 1.23, and bias = 0.055 for FT9700). Considering three groupings for protein concentration (Low: &lt;20%, Medium: ≥20%, but ≤25%, and High: &gt;25%), none of the entries changed from low to high or vice versa between the observed and predicted values for the DA7250 system. Only a single entry moved from a low category in the observed data to a high category in the predicted data for the FT9700 system in the calibration set. Although the FT9700 system outperformed the DA7250 system by a small margin, both systems had the potential to predict protein concentration in pea seeds for breeding purposes. Wavelengths between 950 nm and 1650 nm accounted for most of the variation in pea protein concentration.

Optimization of pea protein and citrus fiber contents for plant based stirred soymilk yogurt using response surface methodology.

This study investigated the optimization of pea protein (PP) and citrus fiber (CF) contents with the goal of producing a clean-label plant-based stirred soymilk yogurt that is free of additives. If CF is absent, a greater PP concentration tends to produce soymilk yogurt with improved physical properties (viscosity, flowability and water holding capacity). A CF concentration of 0.1% helped to improve the physical properties necessary in the production of stirred yogurt; however, an increase in CF concentration to 0.2% or higher would instead cause the physical properties to become unfavorable. The lactic acid bacteria (LAB) count was unaffected by CF content and increased proportionally with PP content. Response surface methodology was employed to investigate how the physical properties were affected by the mixing ratio, and an optimization technique was used to obtain the optimal yogurt mixing ratio. According to the optimization process, the optimal contents of 4% PP and 0.1% CF was obtained with a desirability of 87.1%. This result could provide the basic and fundamental information for developing clean-label plant-based stirred soymilk yogurt as a reference in the future.

Replacement of fishmeal with plant protein in the diets of juvenile lumpfish (Cyclopterus lumpus, L. 1758): Effects on digestive enzymes and microscopic structure of the digestive tract

This study investigated the effects of plant protein concentrates on the activity of digestive enzymes and microscopic structure of the intestine of juvenile lumpfish. The experiment was carried out using triplicate groups of lumpfish of 7 g average initial body weight, to 40 g average final weight, after 54 days. Four experimental diets were used; a fishmeal (FM) based control diet and three test diets with the plant protein concentrates; soy protein concentrate (SPC) and pea protein concentrate (PPC) (1:1 ratio) replacing FM in proportions of 25% (PP25), 50% (PP50) and 75% (PP75), respectively. Nested ANOVA showed several significant treatment differences in histomorphometry. Overall, fish fed test diets exhibited several changes such as shorter mucosal fold height (MFH) in the anterior intestine (AI), increased number of goblet cells (GCs) and width of lamina propria (WLP) in distal intestine (DI), compared to control. Principal component analysis (PCA) on histological indices showed that all three treatment groups (i.e. PP25, PP50 and PP75) had significantly altered overall intestinal architecture, compared to the control group. The observed enteritis was negatively related with the condition factor (CF). Regarding enzyme activities fewer changes were observed across diets. Fish fed the PP50 diet exhibited an increased activity of leucine aminopeptidase (LAP) in the pyloric caeca and a decrease on chymotrypsin (CHY) in the mid intestine (MI) compared to the control. Nevertheless, the overall changes captured by PCA on enzymes were associated only with condition factor (CF) and not with the diets. Overall, histological evaluation confirmed that lumpfish intestinal morphometry was significantly altered by plant protein ingredients at 25%, 50% and 75% levels, but replacing of FM up to 50% did not affected the growth and the enzyme activities up to 75% inclusion level.

Physicochemical and Functional Properties of Membrane-Fractionated Heat-Induced Pea Protein Aggregates.

This study was carried out to investigate the effect of heat pre-treatment of pea proteins at different pH values on the formation of functional protein aggregates. A 10% (w/v) aqueous mixture of pea protein concentrate (PPC) was adjusted to pH 3.0, 5.0, 7.0, or 9.0 followed by heating at 100°C for 30 min, cooled and centrifuged. The supernatant was sequentially passed through 30 and 50 kDa molecular weight cut-off membranes to collect the <30, 30–50, and >50 kDa fractions. The >50 kDa fractions from pH 3.0 (FT3), 5.0 (FT5), 7.0 (FT7), and 9.0 (FT9) treatments had >60% protein content in contrast to the ≤20% for the <30 and 30–50 kDa fractions. Therefore, the >50 kDa fractions were collected and then compared to the untreated PPC for some physicochemical and functional properties. Protein aggregation was confirmed as the denaturation temperature for FT3 (124.30°C), FT5 (190.66oC), FT7 (206.33oC) and FT9 (203.17oC) was significantly (p < 0.05) greater than that of PPC (74.45oC). Scanning electron microscopy showed that FT5 had a compact structure like PPC while FT3, FT7, and FT9 contained a more continuous network. In comparison to PPC, the >50 kDa fractions showed improved solubility (>60%), oil holding capacity (~100%), protein content (~7%), foam capacity (>10%), foam stability (>7%), water holding capacity (>16%) and surface hydrophobicity (~50%). Least gelation concentration of PPC (18%), FT3 (25%), FT5 (22%), FT7 (22%), and FT9 (25%) was improved to 16, 18, 20, 16, and 18%, respectively, after addition of NaCl.

Bioprocessing of Pea Protein can Enhance Fortified Fe But Reduce Zn In Vitro Bioaccessibility.

The bioaccessibility of minerals during food digestion is essential in facilitating absorption and hence mineral bioavailability. Bioprocessing approaches have shown promising effects on Fe and Zn bioaccessibility in plant food matrices. In this study, lactic acid bacteria fermentation or enzymatic hydrolysis was performed on pea protein concentrates (PPCs) to investigate their effects on the bioaccessibility of fortified Fe and Zn salts. Simulated digestion studies revealed that enzymatic hydrolysis was more effective than fermentation. Phytase treatment significantly (P < 0.05) improved Fe3+ bioaccessibility by 5- and 12-fold during fasted and fed digestion stages, respectively. Combined phytase and protease hydrolysis led to a 6- and 15-fold enhancement of Fe3+ bioaccessibility during these stages. None of the bioprocessing approaches led to significant promotive effects on Zn2+ bioaccessibility during fasted or fed digestion. Results of this study show the potential of enzymatic treatment of PPC to significantly promote Fe bioaccessibility.