Evaluation of the Characteristics of Sheep's and Goat's Ice Cream, Produced with UF Concentrated Second Cheese Whey and Different Starter Cultures

Second cheese whey (SCW) is the by-product resulting from the manufacture of whey cheeses. In the present work, sheep (S) and goat (G) SCW concentrated by ultrafiltration (UF) were used in the production of ice creams. Concentrated liquid SCW samples with inulin added as a prebiotic were fermented with yoghurt, kefir and probiotic commercial cultures before being frozen in a horizontal frozen yoghurt freezer. The physicochemical, microbiological and sensory properties of the products were evaluated over 120 days of frozen storage. The products presented significant differences regarding these properties, specifically the higher total solids and protein contents of sheep's ice creams, which were higher compared to their goat ice cream counterparts. Sheep's ice creams also presented higher hardness and complex viscosity, which increased with storage. These ice creams also presented higher overrun and lower meltdown rates. The color parameters of the ice creams showed significant differences between formulations resulting from storage time. In all cases, Lactobacilli sp. cell counts were higher than log 6 CFU/g at the first week of storage. In the case of sheep's ice creams these values were maintained or increased until the 30th day, but decreased until the 60th day. Lactococci sp. counts surpassed log 7 CFU/g in all products, and these values were maintained until the end of storage, except in the case of G-Yoghurt and G-Kefir. Concerning the products containing probiotics, the sum of Lactococci sp. and Lactobacilli sp. counts was of the order log 8-9 CFU/g until the 60th day of storage, indicating that the probiotic characteristics of ice creams were maintained for at least 2 months. All products were well accepted by the consumer panel. Sheep's SCW ice creams were better rated regarding aroma, taste and texture. However, only the ranking test was able to differentiate preferences among formulations.