Obtenção de concentrados proteicos a partir de subprodutos suínos

Abstract

The objective of the present work was to obtain protein concentrates from pork products (liver, kidney and heart) and the evaluation of their physico-chemical and technological properties, in order to add value to these by-products. Initially, protein solubility curves of the pork products (kidney, liver and heart) were constructed to determine the optimum solubility pH of the proteins in their extraction. Thus, protein extractions were performed at alkaline pH, from isoelectric precipitation, pH 9.5 for liver, pH 12.0 for heart and pH 9.0 for kidney. The extracts obtained were centrifuged, lyophilized and milled in a ball mill, obtaining six powder concentrates, characterized by their supernatant and pellet fractions at the determined pH. The concentrates were characterized by their centesimal composition, all of which presented protein content above 68%, which guarantees the denomination of 'concentrate' to the concentrates obtained, in accordance with RDC No. 268 of September 22, 2005, which approves the 'Technical Regulation for Protein Products of Plant Origin'. The highest levels (P <0.05) of water soluble and saline soluble proteins were found in the liver concentrate obtained from the supernatant fraction. The highest water retention capacity (P <0.05) was found in the heart concentrate obtained from the supernatant fraction (332%), which also presented higher value (P <0.05) than the commercial ingredients used as control: isolated soy protein (274%) and whey protein concentrate (107%). Concentrates were evaluated for the objective color in relation to the parameters L *, C *, h * and there was a significant difference (P <0.05) between the concentrates in relation to all these color parameters. All the obtained concentrates were applied in an emulsion system, as substitutes of commercial ingredients, and were analyzed according to their emulsion stability, where the heart concentrate obtained from the supernatant fraction presented lower value (P <0.05) for the contents of exuded fluids. In the analysis of the objective color measure, the added emulsion of the heart concentrate obtained from the supernatant fraction presented a higher value (P <0.05) of C *, due to the presence of hemoglobin. In the analysis of the texture of the gels, the parameters of hardness, cohesiveness and chewing were evaluated, being the highest values (P <0.05) found in the soy protein isolate, since it has a higher protein content and a lower amount of fat. All the obtained concentrates were applied in an emulsion system, as substitutes of commercial ingredients, and were analyzed according to their emulsion stability, where the heart concentrate obtained from the supernatant fraction presented lower value (P <0.05) for the contents of exuded fluids. In the analysis of the objective color measure, the added emulsion of the heart concentrate obtained from the supernatant fraction presented a higher value (P <0.05) of C *, due to the presence of hemoglobin. In the analysis of the texture of the gels, the parameters of hardness, cohesiveness and chewing were evaluated, being the highest values (P <0.05) found in the soy protein isolate, since it has a higher protein content and a lower amount of fat. All the protein concentrates obtained were of equal or superior quality to the commonly used commercial ingredients (soy isolate and whey protein concentrate), but among them, the one that presented the best technological performance was the heart concentrate obtained from the supernatant fraction. Therefore, it is concluded that the production of protein concentrates is an alternative for adding value to pork products such as liver, heart and kidney.