Influence of different processing parameters on the isolation of lupin (lupinus angustifolius l.) protein isolates: A preliminary study

Protein isolates were prepared from full-fat flakes of Lupinus angustifolius L. (cv Vitabor) by salt-induced extraction followed by precipitation with cold demineralized water. Different process parameters were screened to evaluate their significant influences on the extracted or overall protein yields in lab scale. During the extraction, the factors NaCl concentration, pH value and the ratio of flakes to solvent significantly influenced the protein yields, whereas the extraction time can be neglected in a specific range. During precipitation, the salt concentration, the initial protein concentration, the ratio between extract and water, and finally the sedimentation time had significant effect on the overall protein yield. However, the temperature difference between extract and water as well as the order and speed of addition had no considerable impact on the final protein yield. This study gathered important processing parameters for an efficient protein isolation and their suitable ranges for a subsequent optimization

High pressure processing assisted enzymatic hydrolysis - An innovative approach for the reduction of soy immunoreactivity

Soybean (Glycinemax (L.)MERR.) is recognized as a potent food allergen causing one of the most frequent food allergies worldwide. The effect of high pressure processing (HPP) prior to and during enzymatic hydrolysis using the enzyme preparation Flavourzyme® on the degree of hydrolysis (DH), molecular weight distribution (SDS-PAGE) and β-conglycinin (Glym5) immune reactivity of soy protein isolate (SPI)was studied. Enzymatic hydrolysis was carried out at atmospheric pressure (0.1MPa) and HPP (100–600MPa) at 50 °C for 15 min. Pressures higher than 300 MPa enhanced the degradation of Gly m5, which was confirmed by SDS-PAGE and LC-MS/MS analyses. The immunoreactivity of the samples was assessed by invitro sandwich ELISA using mouse monoclonal anti-Gly m5 antibodies. Depending on the antibody tested, the residual immunoreactivity was completely inhibited or significantly impaired up to 99.5% applying HPP during hydrolysis at 400 and 500 MPa. By means of principal component analysis, the beany and green off-flavors characteristic for unprocessed SPI could be reduced by pressure enhanced hydrolysis at 400–500 MPa. The resulting hydrolysates possessed improved protein solubility, foaming activities and oil-binding capacities, which were improved by 45%, 66%, and 210%, respectively. HPP prior to and during enzymatic hydrolysis at 400–500MPa constitutes an innovative approach for the production of low-allergen food ingredients that combine good taste and enhanced functional properties. Industrial relevance: Food allergy has emerged in the last years as the incidence and prevalence are rising dramatically. Up to now, enzymatic hydrolysis is the only feasible method to mitigate soy allergy. However, the major drawback associated with enzymatic hydrolysis is the incomplete destruction of allergenic epitopes and the formation of a strong bitter taste. This research activity demonstrates that high pressure assisted enzymatic hydrolysis using the enzyme preparation Flavourzyme effectively reduces the immunoreactivity of soy proteins. Degree of hydrolysis analysis, SDS-PAGE, mass spectrometry as well as sandwich ELISAwithmousemonoclonalanti-Glym5antibodieshave been applied to analyze the destruction of allergenic proteins as well as to determine the residual immunoreactivity. This study provides preliminary evidence that this innovative combination process of high pressure and enzymatic hydrolysis has great potential to produce tasty low-allergen soy-based food ingredients with good physicochemical properties, i.e. protein solubility and foam ability

Carotenoids in mature green and ripe red fruits of tomato (Solanum lycopersicum L.) grown under different levels of irrigation

The effect of water deficit on concentrations of carotenoids was investigated in ripening tomatoes using HPLC-PDA. Fifteen different tomato cultivars were grown under three levels of water supply and unripe and fully-ripe fruits were harvested at different stages. Water deficit significantly affected several morphological and fruit yield-related parameters. In unripe tomato fruits, the relative concentrations of xanthophyll cycle carotenoids, e.g., violaxanthin and antheraxanthin, were significantly increased at the expense of β-carotene upon limiting the water supply. In ripe fruits, nutritionally-relevant lycopene, β-carotene and lutein levels were broadly independent of water deficit when considering all 15 cultivars, although significant variations were observed among fruits from different genotypes. Our study highlights the importance of careful genotype selection for the production of tomatoes rich in nutritionally-relevant compounds like lycopene and β-carotene