A two-step factorial design for optimization of protein extraction from industrial rapeseed meal after ethanol-assisted reduction of antinutrients

Rapeseed meal is a by-product of oil production with relatively high antinutrient content which limits its application in both feed and food industries. A two-step procedure, including two-level full factorial and central composite designs, was used to assess the influence of five factors namely pH (6 and 12), temperature (20 and 40 degrees C), NaCl concentration (0 and 7.5%), rapeseed meal concentration (2.5 and 5%), and extraction longevity (15 and 60 min) on protein extraction from industrial rapeseed meal subjected to ethanol-assisted reduction of antinutrients. Data demonstrated that pH and its interaction with NaCl influenced protein extractability the most. While still significant, individual effects of NaCl, extraction longevity, temperature and its interaction with pH had a less significant effect on protein yield. Overall. higher protein yields were obtained in response to combining high pH values with low NaCl concentrations, and high pH values with high temperatures. The highest protein yield (59.56 +/- 1.29%) was achieved after extraction of 5% ethanol-treated rapeseed meal at pH 12 with no NaCl addition, at 40 degrees C and extraction longevity of 60 min. A second-order polynomial model for protein yield prediction was generated. The adequacy of the model was verified by coefficient of determination and residual analyses. A high correlation between experimentally obtained and predicted protein yields (R-2 = 0.95) was established. Since extraction conditions are strong determinants of protein characteristics, the predictive model generated in the present work is useful for the selection of factor combinations, which allows for the achievement of optimal protein yield of a product with desired techno-functional properties.info:eu-repo/semantics/publishedVersio

Stability of corn and olive oil-in-water emulsions supplemented with ethanol-treated rapeseed meal protein isolate

Rapeseed meal was treated with 70% ethanol to reduce anti-nutrient compounds, and used in the preparation of a protein isolate. The ethanol- treated rapeseed meal protein isolate (ERPI) was produced by alkaline extraction of proteins (pH 12) followed by isoelectric precipitation at pH 4.5. The aim of the present work was to evaluate the potential of ERPI as an emulsifying agent in corn and olive oil-in-water emulsions under slightly acidic conditions (pH 6). A total of nine emulsions for each type of oil were prepared to assess the significant effect of two variables, oil (5, 10, and 15% w/w) and ERPI protein concentrations (0.25, 0.5, and 1.0% w/w), on emulsion stability. The initial stability was evaluated by Gibbs free energy (ΔG) and lipid particle size distribution, while the dynamics of emulsion stability was investigated along 7 d by turbidity measurement. The increase in concentration of both types of oil positively influenced initial stability of the emulsions as indicated by ΔG. At each oil concentration, the three ERPI supplementation levels resulted in significant differences in ΔG. While in all olive oil-in-water emulsions, the highest initial stability was achieved by the addition of 0.25% ERPI; and in corn oil-in-water emulsions, lower ΔG values were achieved by supplementing either with 0.5 or 1.0% ERPI. With a few exceptions, there was an agreement between Gibbs free energy and microstructural characteristics of the emulsions. With a reduction in turbidity not higher than 30% at day 7, all corn oil-in-water emulsions supplemented with 0.5% ERPI demonstrated a better stability than the emulsions prepared with olive oil.info:eu-repo/semantics/publishedVersio