ACCELERATED MATURATION OF CHEDDAR CHEESE BY THE ADDITION OF LIVE AND HEAT-SHOCKED LACTOBACILLI AND NEUTRASE

摘要

Live and heat-shocked Lactobacillus casei subsp casei (L2A) cultures,supplemented with theproteolytic enzyme Neutrase, have been developed by means of biotechnology,which accelerateCheddar cheese ripening by up to 60% in flavor intensity, as compared tocontrol cheese. Thepresent invention studied Cheddar cheese evolution in detail over a 9-monthripening period byevaluating microbiological, physico-chemical, sensory and rheologicalparameters.This novel integrated process comprises the addition of (1) live Lactobacilluscasei subsp casei(L2A) to control the undesirable microflora, (2) heat-shocked cells of thesame culture at a levelof 1% (v/v), and (3) Neutrase at a level of 1.0 x 10-5 Au/g of cheese.LACTOBACILLI CELLS AND EXTRACTSFOR ACCELERATED CHEESE RIPENINGThe production of matured Cheddar cheese involves considerable costs for thecheese industry,mainly due to a slow microbial process which incurs high costs forrefrigeration and warehousing.Furthermore, impending legislation for mandatory pasteurization to destroypathogens (e.gListeria) will lower the content of useful lactic acid bacteria (LAB),increasing the time necessaryto produce matured cheese.Cheese flavor development is a dynamic process which represents a finelyorchestrated series ofsuccessive and concomitant biochemical events over a period of time, leadingto products withhighly desirable aromas and flavors. None are characterized sufficiently topermit duplication oftheir complete flavor by mixtures of pure compounds thus using indirectmethods to speed upcheese ripening (1).Elevated temperatures during cheese ripening, added enzymes, modified starterand slurry methodhave been commonly used, by the most widely employed method for acceleratedcheese ripeningis the addition of extraneous enzymes to the cheese (2).Although some cheap commercial food grade enzymes are available for the abovepurpose,almost all have their limitations, especially regarding the control of theiraction on milkcomponents, resulting in a rheologically poor final product, and often withbitter flavor.Lactococcus lactis enzymes were introduced to the market as the product«Accelerase» byImperial Biotechnology Ltd (London), but most starter lactococci are unable tomultiply in cheeseand contain less active peptidases (3), and esterases (4) than Lactobacillusstrains (5).The present novel process involves the addition of live and heat-shocked cellsof Lactobacilluscasei subsp-casei L2A, combined with the enzyme Neutrase and elevated ripeningtemperature.The Lactobacillus strain selected was typical of the microflora of goodquality Cheddar cheese,and shows good growth and ensured control of undesirable microflora (6,7).This strain is knownfor its rich peptidases (4), which are responsible for advanced hydrolysis ofmilk casein, and inorder to develop desirable flavors without quality defects.