Valorization of scotta, the by-product of ricotta production, by microbial fermentation for production of a probiotic drink

Ricotta is a typical Italian dairy product obtained after thermal treatment of whey, which determines the coagulation of the whey proteins. The scotta (ricotta cheese whey) is the liquid waste remaining at the end of the process and in Italy this by-product accounts for about 345.000 t each year. Some studies have been conducted so far on its use for bioenergy production. Differently, we explored the potentiality of scotta for food use, in particular for the production of a fermented drink, which could represent a valuable opportunity for the use of the scotta inside the cheese factory. We first collected and characterized several scotta (acid scotta and sweet scotta) from five cheese factories in the Veneto region, which represents the third cheese producing region of Italy. Analyses were conducted to gain information on chemical (lactose, proteins) and microbiological (total counts, main bacterial groups) characteristics. We then evaluated the effect of a thermal treatment as a means to reduce the microbial load without negatively impacting on chemical characteristics. We chose some lactic acid bacteria, either starter, namely Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, and non-starter strains, i.e. Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus johnsonii and Lactobacillus acidophilus, all isolated from commercial dairy products, and evaluated their capability to efficiently develop in Scotta. In addition we also performed some co-inoculations of couples of strains. Results evidence a good to very-good capability of the strains to growth on scotta (up to 109 cfu/ml) and to lower the pH (between 5.4 and 3.8). These results highlight the potential of scotta to be used as substrate for LAB fermentations, which is the first step towards the production of a possible probiotic drink by microbial fermentation of scotta.