Texturization of pea protein isolate by micro compounding.

Twin-screw micro compounding is introduced as a novel technique to process and characterize small plant protein samples under conditions that are relevant for meat analogue processing. Small samples of pea protein isolate (PPI) (5 cm3, corresponding to ∼7 g of hydrated sample) are batch-processed at water contents between 40 and 70 % w/w and temperatures between 90 and 120 °C. Screw speed (100-400 rpm) and residence time (1-9 min) are varied resulting in values of the specific mechanical energy (SME) between ∼20 and 2000 kJ/kg, which is the range relevant for plant protein extrusion. Micro compounding process data provides information on several aspects of the rheological behavior of PPI. Shear thinning behavior is observed for PPI. The viscosity of the PPI during micro compounding was found to exponentially decrease with water content. The temperature dependence is consistent with an Arrhenius-type model. The extruded strands (length: ∼15 cm; diameter: 3.0 ± 0.2 mm) are characterized by scanning electron microscopy (SEM), differential solubility, water holding capacity (WHC), and texture profile analysis (TPA). The hardness as determined from TPA increases linearly with screw speed and residence time, jumps to higher values above the denaturation temperature of the PPI and decreases exponentially with the water content during processing. Micro compounding is found to be a useful technique to convert small plant protein samples at water contents between about 40 and 60 % w/w into texturized matrices and investigate the rheological behavior of plant protein isolates under conditions that are relevant for extrusion processing.

Seed to seed variation of proteins of the yellow pea (Pisum sativum L.).

The existing variation among pea protein isolates' functionality limits their application in food formulations. The source and extent of variations among yellow pea protein profiles was assessed in 10 single seeds of two varieties with different size and weight. A new approach was developed to analyze proteins of yellow pea combining three analytical methods of size exclusion chromatography (SEC), reverse phase high performance liquid chromatography (RP-HPLC), and microfluidic SDS-PAGE, to achieve the highest separation resolution. A high variation of protein concentration was observed not only between varieties, but also among seeds of the same variety. Vicilin to legumin ratio was between 2.72-4.19, and 1.70-2.22 among the individual seeds of AC Agassiz and CDC Saffron varieties, respectively. V/L ratio was significantly different among the individual seeds for both varieties. The amount of some protein fractions/subunits were correlated with seeds' size and weight for AC Agassiz, while such correlations were not observed for CDC Saffron.

Impact of two thermal processing routes on protein interactions and acid gelation properties of casein micelle-pea protein mixture compared to casein micelle-whey protein one.

The influence of two heating protocols (protocol 1 and 2) on protein interactions and acid-induced gelation properties of casein micelle-pea protein mixture (CM-PP) was investigated and then compared to casein micelle-whey protein mixture (CM-WP). The CM:PP and CM:WP protein weight ratio for mixtures was 7.5:2.5, for a total protein content of 4% (pH 6.7). Protocol 1 consisted of a heat treatment (85 °C for 1 h) of CM-PP and CM-WP mixtures, respectively. Regarding protocol 2, casein micelle, pea protein and whey protein stock dispersions were individually pretreated by heating (85 °C for 1 h) before the mixtures were made and heated in the same conditions of protocol 1 (85 °C for 1 h). Heat pretreatment carried out in the protocol 2 significantly increased PP hydrophobicity and reinforced weak interactions of the initial pea protein particles. This pretreatment on protein stock dispersions led to twofold smaller pea protein particles compared to whey protein aggregates. The hydrophobic interactions between pea proteins and casein micelles promoted by the two heating protocols have greatly contributed to improve acid gelation functionalities of CM. Regardless of the heating protocol, acid-induced gelation of the CM-PP mixtures led to the formation of gel networks with a significant increase in stiffness and firmness compared to casein micelle or CM-WP mixtures gels.

Role of chickpea flour in texturization of extruded pea protein.

A growing demand for alternative sources of texturized vegetable protein (TVP) has resulted from various factors including plant allergies, perceived health risks associated with genetically modified organisms (GMO), animal welfare beliefs, and lifestyle choices. Soy and wheat have been the primary ingredients in TVP over the past few decades, but desires for clean label ingredients (especially non-GMO and nonallergenic) have led to demand for alternative plant protein ingredients such as pea protein. To understand the capabilities of pea protein to create meat-like texture with additions of another protein source that also contributes starch, this study focused on extruding pea protein with increasing amounts of chickpea flour (CPF). Six treatments, with inclusions of CPF ranging from 0 to 50%, were processed on a twin-screw extruder to determine the optimal ratio of pea protein isolate to CPF. Bulk density was the greatest with 20% CPF (272 g/L) and resulted in the lowest water holding capacity (55.5%). Texture profile analysis (TPA) hardness, springiness, and chewiness showed optimum results for the 10 and 20% CPF (674 to 1024 g, 72.1 to 80.7%, 400 to 439, respectively). With no CPF addition, protein interactions created a strong network exhibiting extreme springiness (91.3%). Addition of CPF greater than 20% resulted in a detrimental decrease in hardness by 38 to 84% and chewiness by 73 to 92%. Phase transition analysis and specific mechanical energy data provided a greater understanding of the degree of texturization during extrusion. Inclusion of CPF between 10 and 20% led to the optimum protein to starch ratio, allowing adequate protein texturization and creating product characteristics that could potentially mimic meat. PRACTICAL APPLICATION: Pea protein was mixed with increasing levels of chickpea flour to produce a textured plant protein product using extrusion technology. The ratio of protein to starch can be optimized to target specific textural attributes of textured pea protein to closely mimic different meat products like fish, chicken, or beef. The 10 and 20% chickpea flour treatments produced the highest quality products according to textural attributes.

Formulating protein-based beverages for the dysphagia diets of the elderly: viscosity, protein quality, in vitro digestion, and consumers acceptability.

BACKGROUND: Dysphagia is defined as a disorder of the swallowing mechanism. The most common management of dysphagia is diet modification by thickening food and beverages. This study aimed to obtain protein-based beverages for the dysphagia diets of the elderly, corresponding to the 'honey' (III) level of dysphagia fluids according to the National Dysphagia Diet classifications, and containing 100 g kg-1 of good-quality proteins with a high rate of hydrolysis during digestion. RESULTS: Four protein formulations made from pea proteins, milk proteins, a mixture of milk and pea proteins, and milk proteins with added konjac glucomannan, were evaluated on the basis of rheological characterization and proteolysis kinetics during in vitro digestion. The mixture of milk proteins and pea proteins, and the mixture of milk proteins with added konjac glucomannan, showed typical yielding pseudoplastic fluid behavior with similar apparent viscosity but different structural characteristics. These differences were the reason for the differences in proteolysis kinetics during digestion. The mixture of milk and pea proteins showed viscous liquid behavior and was more rapidly hydrolyzed under gastrointestinal conditions than mixtures containing milk proteins and konjac glucomannan acting as a weak gel system. CONCLUSION: We presume that geriatric consumers with swallowing difficulties may benefit from 'honey'-level viscosity, protein-based beverages containing pea and milk proteins through faster proteolysis and better bioaccessibility of amino acids during digestion. © 2020 Society of Chemical Industry.

Chemical, textural, rheological, and sensorial properties of wheyless feta cheese as influenced by replacement of milk protein concentrate with pea protein isolate.

Replacement of milk protein with protein isolates from vegetable resources can significantly influence the characteristics of feta whey less cheese and also decrease the cost of final production. In this study, various blends of milk protein concentrate (MPC) and pea protein isolate (PPI) were mixed at levels of 12% MPC and 0% PPI (MP0), 10% MPC and 2% PPI (MP2), 9% MPC and 3% PPI (MP3), 8% MPC and 4% PPI (MP4), 7% MPC and 5% PPI (MP5), 6% MPC and 6% PPI (MP6) and used in the manufacture of wheyless feta cheese. The chemical, textural, rheological, and sensorial properties, as well as the microstructure of the cheese samples, were evaluated after 1, 15, and 30 days of storage. The general linear model procedure of SAS statistical software was used for statistical analysis. Duncan's multiple range tests was used to compare the means of different treatments. The results showed that all properties of the cheeses were influenced by different levels of PPI due to different total solids content. The use of high concentrations of PPI resulted in a more open protein network, softer structure and decreasing the storage (G') and loss (G″) moduli in the cheeses. Sensory evaluation of the samples revealed that total score in terms of flavor, texture and overall acceptability was gradually decreased with increasing PPI levels, but still preferable for the panelists. Furthermore, for each sample, with increasing levels of PPI, the whiteness and the greenness were decreased, but the yellowness was increased.

Impact of controlled shearing on solubility and heat stability of pea protein isolate dispersed in solutions with adjusted ionic strength.

Pea protein isolates (PPI) have sustained an increasing demand in the food industry as a substitute for animal-origin proteins. Shearing is an integral part of food processing that can change properties of proteins and their functionality. PPI dispersions prepared at 4 or 8% concentration (w/w protein), pH 6.8 or 7.5 and under ionic strength (IS) 100, 200 mM or non-adjusted, were subjected to controlled shearing at two levels (100 or 1500 s-1) during heating at 90 °C for 5 min. All main factors had substantial effects on the tested dependent variables. Shearing at 1500 s-1 significantly improved the solubility and heat stability of 4% PPI at pH 6.8 or 7.5 and IS-100 or 200 mM by 27-43% in comparison to 100 s-1. Following 1500 s-1 treatment, all PPI dispersions showed >85% solubility and heat stability except 4% PPI at pH 6.8 and IS 100 mM (60%). Shearing appeared to alter structural and physicochemical properties of pea proteins as well nature of protein aggregation. Heating accompanied with 100 s-1 shearing mostly resulted in insoluble covalent aggregates while shearing at 1500 s-1 mainly contributed to formation of soluble hydrophobic aggregates.

Design of microbial consortia for the fermentation of pea-protein-enriched emulsions.

In order to encourage Western populations to increase their consumption of vegetables, we suggest turning legumes into novel, healthy foods by applying an old, previously widespread method of food preservation: fermentation. In the present study, a total of 55 strains from different microbial species (isolated from cheese or plants) were investigated for their ability to: (i) grow on a emulsion containing 100% pea proteins and no carbohydrates or on a 50:50 pea:milk protein emulsion containing lactose, (ii) increase aroma quality and reduce sensory off-flavors; and (iii) compete against endogenous micro organisms. The presence of carbohydrates in the mixed pea:milk emulsion markedly influenced the fermentation by strongly reducing the pH through lactic fermentation, whereas the absence of carbohydrates in the pea emulsion promoted alkaline or neutral fermentation. Lactic acid bacteria assigned to Lactobacillus plantarum, Lactobacillus rhamnosus, Lactococcus lactis and Lactobacillus casei species grew well in both the pea and pea:milk emulsions. Most of the fungal strains tested (particularly those belonging to the Mucor and Geotrichum genera) were also able to grow on both emulsions. Although most Actinobacteria and Proteobacteria did not compete with endogenous microbiota (Bacillus), some species such as Hafnia alvei, Acinetobacter johnsonii and Glutamicibacter arilaitensis grew strongly and appeared to restrict the development of the endogenous microbiota when the pea emulsion was inoculated with a combination of three to nine strains. In the mixed emulsions, lactic fermentation inhibited Actinobacteria and Proteobacteria (e.g. Brevibacterium casei, Corynebacterium casei, Staphylococcus lentus) to the greatest extent but also inhibited Bacillus (e.g. Bacillus subtilis and Bacillus licheniformis). Overall, this procedure enabled us to select two microbial consortia able to colonize pea-based products and positively influence the release of volatile compounds by generating a roasted/grilled aroma for the 100% pea emulsion, and a fruity, lactic aroma for the 50:50 pea:milk emulsion. Moreover, the fermentation in the pea-based emulsions reduced the level of hexanal, which otherwise leads to an undesired green pea aroma. Our present results show how the assembly of multiple microbial cultures can help to develop an innovative food product.

In vitro digestibility, protein composition and techno-functional properties of Saskatchewan grown yellow field peas (Pisum sativum L.) as affected by processing.

Saskatchewan grown yellow field pea was subjected to different processing conditions including dehulling, micronization, roasting, conventional/microwave cooking, germination, and combined germination and conventional cooking/roasting. Their nutritional and antinutritional compositions, functional properties, microstructure, thermal properties, in vitro protein and starch digestibility, and protein composition were studied. Processed field peas including conventional cooked yellow peas (CCYP), microwave cooked yellow peas (MCYP), germinated-conventional cooked yellow peas (GCCYP), and germinated-roasted yellow peas (GRYP) exhibited the significantly higher in vitro protein digestibility (IVPD), which was in accordance with their significantly lower trypsin inhibitor activity and tannin content. The SDS-PAGE and size exclusion HPLC profiles of untreated pea proteins and their hydrolysates also confirmed the IVPD result that these four treatments facilitated the hydrolysis of pea proteins to a greater extent. The CCYP, MCYP, GCCYP, and GRYP also exhibited significantly higher starch digestibility which was supported by their lower onset (To), peak (Tp), and conclusion (Tc) temperatures obtained from DSC thermogram, their lower pasting properties and starch damage results, as well as their distinguished amorphous flakes' configuration observed on the scanning electron microscopic image. LC/ESI-MS/MS analysis following in-gel digests of SDS-PAGE separated proteins allowed detailed compositional characterization of pea proteins. The present study would provide fundamental information to help to better understand the functionality of field peas as ingredients, and particularly in regards to agri-food industry to improve the process efficiency of field peas with enhanced nutritional and techno-functional qualities.