Enzymatic Hydrolysis and Fermentation of Pea Protein Isolate and Its Effects on Antigenic Proteins, Functional Properties, and Sensory Profile.

Combinations of enzymatic hydrolysis using different proteolytic enzymes (papain, Esperase®, trypsin) and lactic fermentation with Lactobacillus plantarum were used to alter potential pea allergens, the functional properties and sensory profile of pea protein isolate (PPI). The order in which the treatments were performed had a major impact on the changes in the properties of the pea protein isolate; the highest changes were seen with the combination of fermentation followed by enzymatic hydrolysis. SDS-PAGE, gel filtration, and ELISA results showed changes in the protein molecular weight and a reduced immunogenicity of treated samples. Treated samples showed significantly increased protein solubility at pH 4.5 (31.19-66.55%) and at pH 7.0 (47.37-74.95%), compared to the untreated PPI (6.98% and 40.26%, respectively). The foaming capacity was significantly increased (1190-2575%) compared to the untreated PPI (840%). The treated PPI showed reduced pea characteristic off-flavors, where only the treatment with Esperase® significantly increased the bitterness. The results from this study suggest that the combination of enzymatic hydrolysis and lactic fermentation is a promising method to be used in the food industry to produce pea protein ingredients with higher functionality and a highly neutral taste. A reduced detection signal of polyclonal rabbit anti-pea-antibodies against the processed protein preparations in ELISA furthermore might indicate a decreased immunological reaction after consumption.

Sensory profile, functional properties and molecular weight distribution of fermented pea protein isolate.

Pea protein isolate (PPI, from Pisum sativum L.) was fermented with six different lactic acid bacteria strains for 24 â€‹h and 48 â€‹h. The fermented samples were analyzed regarding their retronasal aroma and taste, their protein solubility, emulsifying and foaming capacity. Changes in the molecular weight distribution were analyzed to monitor potential effects of fermentation on the main allergenic protein fractions of PPI. After 24-h fermentation, PPI's characteristic aroma attributes and bitter taste decreased for all fermented PPI. However, after 48-h fermentation, cheesy aroma, and acid and salty tastes were increased. The PPI fermented with L. plantarum showed the most neutral taste and the panel's highest preference; instead, fermentation with L. fermentum led to a fecal aroma and was the least preferred. The protein solubility and emulsifying capacity decreased after PPI fermentation, while foaming capacity remained constant in comparison to the untreated PPI. The electrophoretic results showed a reduction in the intensity of the allergenic protein fractions; however, these changes might be attributed to the reduced protein solubility rather than to a high proteolytic effect of the strains. Fermentation of PPI for 24 â€‹h and 48 â€‹h might not be a suitable method for the production of highly functional pea proteins. Further modification methods have to be investigated in the future.

Screening of Twelve Pea (Pisum sativum L.) Cultivars and Their Isolates Focusing on the Protein Characterization, Functionality, and Sensory Profiles.

Pea protein concentrates and isolates are important raw materials for the production of plant-based food products. To select suitable peas (Pisum sativum L.) for protein extraction for further use as food ingredients, twelve different cultivars were subjected to isoelectric precipitation and spray drying. Both the dehulled pea flours and protein isolates were characterized regarding their chemical composition and the isolates were analyzed for their functional properties, sensory profiles, and molecular weight distributions. Orchestra, Florida, Dolores, and RLPY cultivars showed the highest protein yields. The electrophoretic profiles were similar, indicating the presence of all main pea allergens in all isolates. The colors of the isolates were significantly different regarding lightness (L*) and red-green (a*) components. The largest particle size was shown by the isolate from Florida cultivar, whereas the lowest was from the RLPY isolate. At pH 7, protein solubility ranged from 40% to 62% and the emulsifying capacity ranged from 600 to 835 mL g-1. The principal component analysis revealed similarities among certain pea cultivars regarding their physicochemical and functional properties. The sensory profile of the individual isolates was rather similar, with an exception of the pea-like and bitter attributes, which were significantly different among the isolates.

Development of Monoclonal Antibodies against Pea Globulins for Multiplex Assays Targeting Legume Proteins.

Legume proteins are widely used as food ingredients, but only some (soybean, lupin, and peanut) must be declared under consumer safety regulations to protect allergy sufferers. It is not yet mandatory to declare pea proteins as allergens even though they are predicted to be allergenic based on cross-reactivity in sensitized people. The processing of legume proteins can modify their allergenic properties and hence the need for specific and precise methods for the detection of all major legume allergens. There are many commercially available tests for known food allergens but not for ingredients that are yet to be classified as allergenic. We therefore generated sets of pea-specific antibodies targeting globulins to be used in a multiplex assay for the simultaneous detection of soybean, lupin, peanut, and pea proteins. We focused on the 7S globulin family, which is the least conserved among the four legumes, allowing the specific detection of proteins from each species. Having confirmed the specificity and sensitivity of the multiplex assay, we evaluated different processing steps for proteins rich in pea globulins to demonstrate the impact of food processing on antibody binding. Our sensitive multiplex assay provides a fast and reliable method for the specific detection of soybean, lupin, peanut, and pea allergens and is therefore ideal for food safety and authenticity testing applications.

Protein-Rich Flours from Quinoa and Buckwheat Favourably Affect the Growth Parameters, Intestinal Microbial Activity and Plasma Lipid Profile of Rats.

In recent years, dietary products with quinoa and buckwheat have attracted attention mostly due to the high nutritive value of their protein fraction. However, their dietary effect on intestinal microbiota activity and related systemic responses are still poorly understood. Therefore, a 2 week study of twenty-eight growing male Wistar rats was conducted to investigate the effects of quinoa (QU) and buckwheat (BK) protein-rich flours on the growth parameters, intestinal microbial activity, plasma lipid profile, and inflammatory markers. The biological value of protein and body weight gain were considerably increased in the QU and BK groups compared with those in the soy protein isolate group. Moreover, both flours increased the microbial activity of α-glucosidase, ß-glucosidase, and α-galactosidase and the concentration of short-chain fatty acids in the caecum. The studied flours favourably reduced the plasma total cholesterol and LDL cholesterol. In rats fed a diet with QU, elevated levels of plasma interleukin 6 and alanine transaminase were observed. The effect of QU on inflammatory markers may be related to the increased expression of aryl hydrocarbon receptor in the liver and to the decreased level of plasma albumin. In conclusion, quinoa and buckwheat protein-rich flours are valuable sources of proteins that favourably affect growth parameters, gut metabolism, and blood lipid profile in rats; however, only the buckwheat flour has no effect on inflammatory processes.

Influence of the Isolation Method on the Technofunctional Properties of Protein Isolates from Lupinus angustifolius L.

The technofunctional properties of 2 protein isolates from Lupinus angustifolius L. Vitabor isolated by different procedures were investigated. The lupin protein isolate prepared by aqueous alkaline extraction with subsequent isoelectric precipitation (ILP) showed a significantly higher degree of protein denaturation and lower denaturation temperatures than the one obtained by aqueous salt-induced extraction followed by dilutive precipitation (MLP) as determined by differential scanning calorimetry. Rheological investigations revealed higher firmness and a viscoelastic solid-like behavior of ILP, in contrast to MLP that showed viscoelastic, liquid-like properties. Protein solubility of MLP was higher compared to ILP and solubility minima were slightly different for both lupin protein isolates. The protein isolates exhibited different technofunctional properties with ILP showing higher water binding capacity, lower oil binding capacity and lower emulsifying capacity than MLP. This reflects the different putative application of both lupin protein isolates as food ingredients, for example for ILP as a moisture enhancer and for MLP as a "natural" emulsifier in mixed food systems.

Protein distribution in lupin protein isolates from Lupinus angustifolius L. prepared by various isolation techniques.

Differences in the protein distribution of various protein isolates from Lupinus angustifolius L. Vitabor were identified as affected by the isolation procedure (alkaline and/or salt-induced extraction followed by isoelectric and/or dilutive precipitation). Protein isolates extracted in alkaline solution showed higher protein yields (26.4-31.7%) compared to salt-induced extraction (19.8-30.0%) or combined alkaline and salt-induced extraction (23.3-25.6%). Chemical variations among the protein isolates especially occurred within the albumins. Protein isolates precipitated isoelectrically showed the highest contents, whereas protein isolates precipitated by dilutive showed the lowest contents of conglutin δ. Furthermore, the alkaline subunits of conglutin α and conglutin γ decreased during alkaline extraction compared to salt-induced extraction. A decrease in protein-bound polar and basic amino acids was shown after protein isolation. In contrast, the amounts of nonpolar, aliphatic, aromatic, hydroxylated and sulfur-rich amino acids were higher in the lupin protein isolates compared to the lupin flakes. However, the functional side chains could not be related to the specific molecular arrangements of the protein isolates, as a similar amino acid composition was found among the protein isolates.