Mass transfer processes involved in Gouda cheese manufacture, in relation to casein and yield

This paper gives an overview of milk composition in relation to mass transfer from milk to cheese in the manufacture of Gouda cheese. All possible mass transfer processes are discussed and quantified as far as possible. Use is made of published data in the literature, unpublished data and some newly collected data. Contrary to what is common in the literature, this paper relates cheese yield to 100 kg paracasein instead of 100 kg milk. This approach has a close relation to common practice of filling a curd processor with such an amount of milk that a constant amount of cheese will be obtained. It was concluded that the paracasein content of milk to be used for cheese making cannot be accurately calculated from an apparent protein estimation (including non-protein nitrogen) nor from a true protein estimation, but may be derived from infra-red true protein readings in milk and its corresponding rennet whey. The calculated ratio of minerals and acids to protein in cheese was not completely in balance with the estimated ratio. It was not possible to derive seasonal variation of the amount of colloidal minerals and acids per 100 kg paracasein from available information. It seems to be a variation of almost 1 kg per 100 kg paracasein. There are also some conflicting data about the amount of serum proteins in cheese. There are three main reasons why it is better to take the paracasein content as starting point: i) its determination resembles closely the actual cheese-making process, ii) there is no problem with the (unknown) content of carbohydrate in kappa-casein (because it is removed by rennet), iii) adsorption of peptides to paracasein (such as proteose-peptone) is included in the paracasein determination. It is suggested for future research to collect accurate figures regarding the seasonal pattern of the colloidal minerals and acids associated with (para)casein. Also, additional accurate cheese-making experiments are necessary to calculate the retention of individual minerals and acids in Gouda cheese.