344: Optimization of Pulse Electric Field-Assisted Protein Extraction From Lupin Flour

Introduction

Present production abilities cannot meet the growing demands for proteins. Lupin is an interesting source with high protein content, but optimal protein extraction procedures are essential to obtain high-quality protein isolates. PEF-assisted is a prominent technology that produces membrane electroporation, increases permeability, and promotes mass transfer. Thus, this study optimized PEF parameters using a Box-Behnken experimental design to facilitate protein extraction from lupin flour.

Methods

Lupin flour obtained from Lupinus luteus L. was used. The independent variables were the pulse width (x1; 20-60-100 µs), number of pulses (x2; 100-150-200 pulses), and voltage (x3; 5000-7500-10000 V), while the dependent variables were total yield (y1) and protein purity (y2). Response surface methodology (RSM) based on Box-Behnken design (3 factors and 3 levels; 3K BBD) with 15 experimental runs and three center points (3x1x15) was used to obtain the optimal extraction conditions. For each run, 100 g of lupin flour was treated and the protein extraction was carried out using alkaline solubilization (pH 10.3), and isoelectric precipitation (pH 4.7). The lyophilized protein isolates were analyzed.

Results

The experimental results showed that yield varied between 20.38% and 26.22%, while purity ranged from 87.14% to 89.28%. The regression model and ANOVA test were applied to determine the functional relationship for approximation and prediction of responses. The coefficients showed high model accuracy (R2=0.6688 for yield and R2=0.7363 for purity) and the lack of fit test was found to be non-significant, which corroborated the adequacy of the model in representing the experimental data outcomes for all variables.

The ANOVA results indicated that the number of pulses (linear and quadratic effects) had a significant effect on the yield extraction, while pulse width (linear and quadratic effects) and pulse width x number of pulses interaction influenced purity. The optimized extraction conditions were: pulse width = 24 µs, number of pulses = 200, and voltage = 10,000V, obtaining 25.55% of total yield and 89.41% of purity (predicted values). The model was validated (predicted/experimental data-%RSD <10%)

Significance

PEF-assisted extraction (under optimized conditions) of lupin proteins results in a high yield and a purity close to 90%, which allows obtaining high-quality protein isolates.

Authors: José Manuel Lorenzo, Noemí Echegaray, Rubén Agregán, Mirian Pateiro, Roberto Bermúdez, Rubén Domínguez-Valencia