Processing of Mozzarella cheese wheys and stretchwaters: A preliminary review

Mozzarella cheese is one of the cheeses that has achieved the most significant growth in production in the past century. This has resulted in the concomitant production of large amounts of whey and (in the case of Mozzarella cheese) stretchwater. For decades, these products were often dumped as waste products or used as animal feed. However, it is no longer possible to do so. First, these by-products have a high oxygen demand, and thus a great environmental impact. Second, the high nutritional value of their constituents (whey protein, lactose, etc.) makes it necessary to make use of these products and, as food ingredients, this begins with concentration and spray drying of the bulk material. These stages are known to be especially difficult in the case of Mozzarella cheese wheys and stretchwaters, and there is thus a need to study and explain the role of the minor compounds that were found in Mozzarella cheese wheys, including water-binding properties and low glass transition temperature. Solving these problems requires a good understanding of the origins of these by-products (i.e. Mozzarella cheese making) and of water dynamics. The aim of this review is to provide an overview of the current knowledge on the composition of Mozzarella cheese wheys and stretchwaters, their origin in cheese making and the possible implications of their composition on the different water elimination stages.