Impact of Ultrafiltration and Spray-Drying on the Techno-functional Properties of a Pork Liver Extract

Abstract Pork liver, a co-product of the meat industry, remains underutilised in Western countries due to low consumer acceptance. Given the high number of pigs slaughtered, a considerable surplus of livers is generated, underscoring the need for valorisation strategies to enhance their economic and functional value. One interesting approach involves extracting soluble proteins for use as techno-functional ingredients. However, low extraction yields limit the ability to characterise heat-induced gelling behaviour. This study investigates the impact of ultrafiltration followed by spray drying on the techno-functional properties of a soluble pork liver protein extract recovered at pH 6.0. Special attention is placed on the gelling properties of both ultrafiltration retentates and reconstituted solutions from spray-dried retentates, although surface-active properties—such as foaming and emulsifying properties—were also evaluated and compared to the original liver extract. The results clearly demonstrate both retentates and reconstituted solutions from powders form solidified products when solutions containing 8% protein concentration and adjusted to pH 6.0 are subjected to a heat-induced gelation at 90 °C for 45 min. However, the treatments yield different textural outcomes: while the products obtained from ultrafiltration retentates exhibit a soft, spreadable consistency, those derived from spray-dried retentates form firmer and more cohesive structures. These differences underscore the impact of applied technological processes on the gelling behaviour of the protein extract and highlight the potential application of these protein fractions as functional agents for structuring and water retention in heat-processed food products. In contrast, they are not intended to serve as surface-active ingredients.