Enzyme-Modified Cheese

This article deals principally with the technology of enzyme-modified cheese (EMC) manufacture and outlines the basis of the current EMC manufacturing processes, with an emphasis on the role of emulsification of substrate and the use of exogenous enzymes to develop an intense EMC flavor. Overall, the EMC technology delivers high-intensity cheese flavors for inclusion into a wide range of processed consumer foods. EMC technology has developed from studies of cheese flavors produced using a curd slurry technique. The original EMC process involved mixing fresh curd and NaCl solution to make an emulsion of approximately 40% solids. Enzymes and preservatives were added, and the slurry was incubated at 30 °C for 4–5 days with daily agitation, after which the characteristic cheese flavors were developed. This work demonstrated the potential for rapidly generating a range of intense cheese flavors from cheese substrates by modification of process parameters. The basic manufacturing process for EMC, as outlined in this article, still involves the use of cheese curd substrates which are heat-treated, emulsified, and incubated with exogenous proteinases, peptidases, and lipases, and finally heat-inactivated. In common with natural cheese, EMC flavors are primarily generated through the proteolytic and lipolytic pathways, but in a physicochemical environment that differs markedly from that of natural cheese. Glycolysis does not play a major role in EMC flavor, mainly because in natural cheese, the glycolytic substrates lactose and citrate are utilized quite quickly in the process, and apart from some exceptions, only affect the flavor of short ripened or young cheeses. The degree of protein and lipid hydrolysis in EMC is generally much higher than that found in natural cheese. Lipolysis, in particular, plays a significant role in the generation of cheese flavor intensity and aroma in EMC, which is in contrast to many semi-hard natural cheese varieties where the role of lipolysis is much more subtle. Proteolysis in EMC production produces high levels of peptides and free amino acids that are non-volatile and contribute to taste, and therefore, tend to provide sweet, salty, bitter, and savory flavors. Despite the economic importance of this product range, there is a lack of detailed published information on the mechanisms of flavor development and the role of individual enzymes and starter cultures in the development of EMC flavor. Recently, natural biotransformation processes are receiving lots of interest due to sustainability, use of milder processing conditions, positive environmental aspects, and consumer acceptability. This is likely to result in more natural cheese concentrate processes, such as EMC, being utilized more in food production into the future.