Recovery and Extraction of Technofunctional Proteins from Porcine Spleen Using Response Surface Methodology

Porcine spleen is an edible meat by-product from industrial slaughterhouses with a low commercial value that is generally underutilised. In this work, response surface methodology was used to optimise the conditions for protein extraction from porcine spleen. Factors examined were pH (4.3–8.6) and salt concentration (0–4%) of the extraction buffer. The response of several physicochemical characteristics and technofunctional properties of spleen protein fractions as a function of two particular controllable factors of the fractionation process was fitted to second-order polynomial models. The proximate composition (%) of porcine spleen was as follows: moisture (78.9 ± 0.4), protein (17.2 ± 0.7), fat (2.9 ± 0.4), total ash (1.34 ± 0.1) and hydroxyproline (0.20 ± 0.1). Fe content (mg/kg) was 275.5 ± 63. SDS-PAGE patterns of the spleen protein fractions revealed multiple bands with low and high molecular weights from 15 to 220 kDa, corresponding to sarcoplasmic, myofibrillar and connective tissue proteins in both soluble and insoluble fractions with slight differences due to pH and ionic strength extraction conditions. Significant second-order models were obtained for the response variables (protein solubility), foaming and emulsifying properties of soluble fraction, and redness (a*), chroma (C*) and retention properties -cooking loses and water holding capacity- of insoluble residue from porcine spleen. The analysis of the fitted model plots and the ANOVA confirmed that model fits were satisfactory.