Pork liver as a source of protein with excellent foaming properties

Pork liver is a protein-rich offal, generated in large quantities in the meat industry and considered non-allergenic, although not highly appreciated by Western consumers. The recovery of its proteins through a simple and easily scalable process with the purpose of obtaining economical and environmentally friendly techno-functional ingredients might be an alternative for its valorization. Of great interest are protein fractions with good foaming properties that can act as substitutes for other highly allergenic proteins in food formulation. In this study, protein extractions from fresh pork livers were performed using buffer solutions adjusted to different pH (from 4.0 to 8.5), without a subsequent concentration/purification step. The main parameters evaluated were yield and foaming properties of the recovered extracts; their physicochemical characteristics and the SDS-PAGE protein profiles were determined as well. Acceptable extraction yields (> 50% of the total protein) were obtained using buffer solutions adjusted to pH ≥ 4.80, but their foaming properties were poor. By contrast, the extracts recovered using buffers adjusted to pH ≤ 4.75 were capable of forming very voluminous and stable foams, although rather low yields were achieved under these conditions (31.5-36.0% of the total protein). In addition to the profile of solubilized proteins, a low fat and relatively high carbohydrate content in the extracts seem to contribute to their excellent foaming properties. Therefore, protein extracts from fresh pork liver obtained using buffer solutions adjusted to pH 4.0-4.5 (extract pH: 5.3-5.6) could be a real alternative to other protein foaming agents that cause food allergies, in a simple, cost-effective and sustainable way ​
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