Advances in Understanding the Antioxidant and Antigenic Properties of Egg-Derived Peptides.

Pepsin, trypsin and proteinase K were used in the present study to hydrolyse the proteins from whole eggs, yolks or whites, and the resulting hydrolysates were characterised in terms of antioxidant and IgE-binding properties, using a combination of in vitro and in silico methods. Based on the degree of hydrolysis (DH) results, the egg yolk proteins are better substrates for all the tested enzymes (DH of 6.2-20.1%) compared to those from egg whites (DH of 2.0-4.4%). The SDS-PAGE analysis indicated that pepsin and proteinase K were more efficient compared to trypsin in breaking the intramolecular peptide bonds of the high molecular weight egg proteins. For all the tested substrates, enzyme-assisted hydrolysis resulted in a significant increase in antioxidant activity, suggesting that many bioactive peptides are encrypted in inactive forms in the parent proteins. The hydrolysates obtained with proteinase K exhibited the highest DPPH radical scavenging activity (124-311 µM Trolox/g protein) and the lowest residual IgE-binding capacity. The bioinformatics tools revealed that proteinase K is able to break the integrity of the main linear IgE-binding epitopes from ovalbumin and ovomucoid. It can be concluded that proteinase K is a promising tool for modulating the intrinsic properties of egg proteins.

Preliminary Investigations into the Use of Amylases and Lactic Acid Bacteria to Obtain Fermented Vegetable Products.

Legumes are valuable sources of proteins and other functional components. However, the high starch content can be an impediment in developing new vegan food formulations. Enzyme-assisted hydrolysis was used to hydrolyze the starch from chickpea and broad bean vegetable milk to further develop vegetable lactic acid-fermented products. The antioxidant activity of legumes was tested, and it was observed that the overall antioxidant activity (DPPH radical scavenging ability) significantly increased after enzyme-assisted hydrolysis while total phenols content decreased. The obtained vegetable milk was then fermented using exopolysaccharides-producing lactic acid bacteria. A significant decolorization was observed after fermentation in the case of broad bean-based products. Rheological behavior of the fermented products was determined using small amplitude oscillatory measurements and the three-interval thixotropy test. Results showed higher complex viscosity values for broad bean-based products, which displayed a weak gel-like structure. The starter cultures used for vegetable milk samples fermentation influenced the resistance to flow.

Impact of broad beans addition on rheological and thermal properties of wheat flour based sourdoughs.

Broad bean flour is a valuable source of proteins and micronutrients and can efficiently balance the nutritional value of wheat flour. The aim of the study was to assess the impact of wheat flour substitution by native and germinated broad beans on the water related, thermal and rheological properties of the composite flours and sourdoughs. Regardless of the investigated flour, temperature increase resulted in significant decrease of water soluble index. Addition of broad bean to wheat flour affected the swelling power. Differential scanning calorimetry measurements on flours indicated two peaks at ∼70 °C assigned to starch gelatinization, and ∼100 °C attributed to amylose-lipids complexes disruption. The same thermal dependent events were highlighted through the rheometric temperature ramp test. Sourdoughs were further obtained out of the composite flours and dynamic rheometric analysis showed that fermentation improved flow resistance. Wheat substitution by broad bean flour increased sourdoughs consistency due to the higher protein content.

Effect of gluten, egg and soy proteins on the rheological and thermo-mechanical properties of wholegrain rice flour.

The effect of protein addition on the rheological, thermo-mechanical and baking properties of wholegrain rice flour was investigated. Gluten, powdered eggs and soy protein concentrate were first analyzed in terms of rheological properties, alone and in admixture with rice flour. The temperature ramp tests showed clear differences in the rheological behavior of the batters supplemented with different proteins. The highest thermal stability was observed in case of soy protein samples. Frequency sweep tests indicated significant improvements of the rheological properties of rice flour supplemented with 15% gluten or soy proteins. The thermo-mechanical tests showed that, due to the high fat contents and low level of free water, the dough samples containing powdered eggs exhibited the highest stability. Addition of gluten resulted in a significant decrease of the dough development time, whereas samples with powdered eggs and soy proteins were more difficult to hydrate. The incorporation of proteins into the rice flour-based dough formulations significantly affected starch behavior by decreasing the peak consistency values. Concerning the quality of the rice flour-based breads, soy protein addition resulted in lighter crumb color and increased texture attributes, samples with gluten had better resilience and adhesiveness, whereas breads with egg protein were less brittle.