Selected Quality Attributes of Freshwater Mussel Powder as a Promising Ingredient for Pet Food

SIMPLE SUMMARY: Bivalves such as clams, mussels, and oysters provide a good source of protein, glycogen, and minerals. The high-value compounds and bioactive properties of these organisms are well known and confirmed by numerous scientific studies. During the last two decades, the freshwater mussel Sinanodonta woodiana as one of the most invasive species, has penetrated into Europe along with fish shipments from Asia. Numerous studies indicate that both the soft tissues and mussel shells of this low-grade species may constitute promising biomaterial with potential processing ability. Due to growing interest in new raw materials having been observed recently in the pet food market, this study aimed to obtain and evaluate selected quality attributes of freshwater pond mussel powder. After initial ecotoxicity testing in vitro, powdered mussel tissue was evaluated with respect to its basic physicochemical and functional properties, such as solubility, emulsifying capacity, and gel-forming ability. The study also provides novel information about electrophoretic protein profile and amino acid composition, including taurine content. Based on the results obtained in this study, it can be concluded that tissues of mussels available locally from lakes and ponds can be proposed as an interesting source of new ingredients for developing formulated pet food products. ABSTRACT: The aim of this study was to describe the quality attributes of a freeze-dried preparation obtained from freshwater mussel Sinanodonta woodiana (SW) soft tissue in respect to its potential as a novel pet food ingredient. After ecotoxicological testing of the raw material with MARA (Microbial Assay for Risk Assessment), the basic physico-chemical properties of the powder, such as approximate composition, bulk density, color parameters, water activity, electrophoretic analysis (SDS-PAGE), solubility, gelling and emulsifying capacity, were analyzed. The powder with a water activity of 0.43 offers a toxically safe preparation that contains over 34% protein/100 g of dry matter (DM). The SDS-PAGE profile showed twelve protein bands with a molecular weight (MW) ranging from >250 to 10 kDa. Taurine content has been estimated at an essential amount above 150 mg/100 g of DM. The powder possessed desirable emulsifying properties with 230 mL per 1 g and demonstrated the ability to form a firmer gel with a strength of 152.9 g at a temperature above 80 °C with at least 10% protein content. The L*, a*, and b* values characterizing powder color were found to be 69.49, 16.33, and 3.86, respectively. The SW mussel powder seems to be a promising ingredient that can be added with other binding or gelling agents in order to improve both the taste and acceptance of the final pet food products.