Application of the response surface methodology for optimization of whey protein partitioning in PEG/phosphate aqueous two-phase system

Optimization of PEG–salt aqueous two-phase systems by design of experiments

“…12 has been frequently set to ± 1.41 [6,18,23,35,38,[46][47][48][49] for the optimization of PEG-salt ATPS. Hence, the CCC design for three factors is obviously represented by a hyperspherical experimental arrangement due to corner and axial experiments approximating a spherical surface (Fig.…”

“…In general, models/equations are validated by a statistical procedure, at which the statistical significance of all effects on the model or their corresponding regression coefficient parameters with less than 95 % significance (95 % confidence level) are initially considered as non-significant according to the Student's t-distribution or Student's t-test (t-test) and the probability of error or probability values (p-values), i.e., p > 0.05 [10,17,19,22,34,43,45,49]. Hence, these effects or parameters are excluded and added into the residual error term and a new ANOVA is performed for the complete and reduced model [22,37,38,45,52]. That means, the new reduced models are obtained for response variables by using only significant factors in a regression analysis [56], at which the p-value, defined as the smallest level of significance leading to the rejection of null hypothesis, is smaller than 0.05 (p < 0.05), which means that a particular model term is statistically significant at 95 % confidence level, thus representing a…”

“…In other words, the F-test is generally providing a method for the determination of significant differences between different variation sources in the experimental results, i.e., the significance of regression (SOR), the lack-of-fit (LOF), and the coefficient of determination (R 2 ), at which the ANOVA table for response variables is including the mean squares of all variance sources (e.g., regression, LOF, etc.) and is finally comparing the relative to the residual (prediction error) variance [17,19,30,38]. When full second-order models (models covering all two parameter interactions) are not accepted by the previous mentioned tests, they can be improved by removing model terms, until the obtained…”

“…In this context, a multiple regression analysis of the experimental data is performed to evaluate the optimal mathematical model equation, at which target output responses can be analyzed by response surface or contour plots as outlined separately ahead [7,10,18,34,38].…”

Purification and concentration of cheese whey proteins through aqueous two phase extraction

“…The major proteins of whey are α-lactalbumin (αla), β-lactoglobulin (βlg), and bovine serum albumin (BSA) (Perumalsamy & Murugesan, 2012). Both, αla and βlg are excellent source of essential amino acids (Alcântara et al, 2011) and, in general, whey proteins possess high biological value, because they are almost totally absorbed by the digestive system (Kreczmann et al, 2015). However, whey contains also certain amounts of fat (Fagan, Castillo, O'Callaghan, Payne, & O'Donnell, 2009) that hinder recovery of proteins (Torkamani et al, 2016), and high concentration of lactose (Kalaivani & Regupathi, 2015), which has been identified as the main problem for the use of this by-product (De Souza et al, 2010), because many people around the world suffer from lactose intolerance (Jelen & Tossavainen, 2003).…”