The objective of this work was the use of goat and sheep liquid whey concentrates (LWCs) produced by ultrafiltration (UF) for the manufacture of frozen yoghurts with or without different concentrations of inulin. In a first step, natural yoghurts using only goat and sheep LWCs as raw material were obtained. One day after production, these yoghurts were used to produce frozen yoghurts with different concentrations of added inulin. The physicochemical charateristics of ewe´s and goat´s yoghurts were significantly different regarding dry matter, protein, fat and minerals. Ewe´s yoghurts were solids while goat´s yoghurts behaved as a viscous liquid. Frozen yoghurts with different levels of inulin addition also presented significant differences concerning physicochemical and microbiological characteristics. Overrun was similar for all formulations except for the one produced with ewe’s LWC containing 5.0% inulin, which presented a significantly higher value. Higher meltdown rates in goat’s whey frozen yoghurts were observed. The survival rates of lactic acid bacteria were lower than data reported for similar products. Concerning sensory acceptance, both products showed encouraging results. It can be considered that the production of frozen yoghurts by using LWCs as main ingredient can be an interesting option to broaden the product’s portfolio of small/medium scale dairy producers.

The search for new food products that promote consumers health has always been of great interest. The dairy industry is perhaps the best example regarding the emergence of new products with claimed health benefits. Cheese whey (CW), the by-product resulting from cheese production, and second cheese whey (SCW), which is the by-product of whey cheese manufacture, have proven to be potential ingredients for the development of food products with improved nutritional characteristics and other functionalities. Nowadays, due to their nutritional quality, whey products have gained a prominent position among healthy food products. However, for long, CW and SCW were usually treated as waste or as animal feed. Due to their high organic content, these by-products can cause serious environmental problems if discarded without appropriate treatment. Small and medium size dairy companies do not have equipment and structure to process whey and second cheese whey. In these cases, generally, they are used for animal feed or discarded without an appropriate treatment, being the cause of several constraints. There are several studies regarding CW valorization and there is a wide range of whey products in the market. However, in the case of SCW remains a lack of studies regarding its nutritional and functional properties, as well as ways to reuse this by-product in order to create economic value and reduce environmental impacts associated to its disposal.

Conclusions: It could be concluded that small/medium scale dairy plants can use UF equipment with the aim to valorize sheep´s and goat´s CW through the production of dairy formulations with added prebiotics and probiotics, while reducing the environmental impact of their activities.

Bovine whey cheese (WC) is a product from southern European countries that presents some challenges: their elaboration process involves high energy inputs, the yield is low and WC has a short shelf-life. The application of ultrafiltration to bovine whey before its manufacture and the employment of protective cultures can reduce these disadvantages. The aim of this work was to manufacture whey cheeses using ultrafiltrated (UF) concentrated bovine cheese whey with added probiotics or probiotics plus protective cultures. Three types of WC were produced: control, without any addition (C); with the addition of the probiotic Lactobacillus acidophilus (LA5); with the addition of Lactobacillus acidophilus plus a protective culture containing Lactobacillus paracasei and Lactobacillus rhamnosus (LA5FQ4). The WCs were stored under refrigerated conditions for 28 days. The products with added cultures presented a lower pH and a higher titratable acidity when compared to the control. Sample LA5 presented the lowest pH and the highest titratable acidity while LA5FQ4 presented intermediate values. Slight differences were observed between products regarding color parameters, chiefly as a result of storage time. The samples with added cultures were firmer when compared to the control, showing LA5 cheeses the highest values at the end of the storage. Lactobacilli and lactococci counts were of the order of log 8-9 CFU/g for the products with added cultures. Lower levels of yeasts and moulds were detected on the sample with the protective culture (LA5FQ4), that by the end of storage presented counts one log cycle lower than C and LA5. Hence, it is evident the beneficial impact of the protective culture on the shelf life of the product. In what concerns to sensory evaluation, LA5FQ4 cheeses obtained the highest scores regarding all parameters evaluated. It could be concluded that the use of UF associated to the addition of protective cultures can be very useful to reduce the energy consumption of the process, prolong the shelf life of WC, and to improve its sensory properties.