Development and quality evaluation of a fermented dessert made from donkey milk fortified with oat flour, wheat germ oil, and pomegranate extract

The dairy sector is constantly innovating in response to the critical issues connected to sustainability and healthiness and to the increasing consumer demand for products with nutritional benefits. This study aimed to develop an innovative fermented dessert made from donkey milk (FDMD) added with oat flour (OF) and wheat germ oil (WGO). Different concentrations of OF and WGO (8, 10, and 12, and 3, 5, and 7 % w/w) were tested to optimize texture and, for this purpose, D-optimal mixture design was used. The best structural formulation obtained (11.5% w/w of OF and 3.5% w/w of WGO) was fortified with two further ingredients including dark chocolate 3% w/w, and pomegranate extract rich in ellagic acid (0.5 w/w, FDMD-A, and 1% w/w, FDMD-B) for improving flavor and nutritional properties. The quality and safety characteristics of the product during 30 days of storage were evaluated. The application of the Design of Experiment (DoE) proved successful in achieving the desired structural characteristics using 11.5% w/w OF and 3.5% w/w WGO. The addition of pomegranate extract did not negatively influence the textural and rheological characteristics of the samples, instead acting positively on the stability of the product during storage. Moreover, it had an impact on total polyphenol content and antioxidant activity, showing better results at 1% level of fortification (FDMD-B). The shelf-life study demonstrated that both formulations were microbiologically safe and stable and were appreciated by the panel involved in the sensory analysis. Finally, poor proteolysis took place during the 30-day storage period, indicating that the two samples did not significantly change over the 30 days of storage.