Enzymes and Cultures
by Lori Dahm
How careful selection can speed cheese production and yield desired functionalities.
The art of cheesemaking is centuries old, and the science behind cheesemaking is similarly qualified with decades behinds its study. Few changes have been necessary in either the art or the science of cheese production within the past 50 years.
However, the effects brought on by the industrialization of food processing have created the need for greater productivity and efficiency in the making of cheese. To meet these demands, manufacturers began using additional enzymes to yield faster cheese ripening, and adjunct cultures to balance flavor development.
Today, the cheese manufacturing industry is huge, and the use of enzymes and cultures widespread. Suppliers of the enzyme and culture ingredients have continued to refine the selection of enzymes and cultures for specific effects in the final cheese product.
“Enzymes and cultures are not mutually exclusive systems; they work in very different but complementary ways to yield many varieties of cheese. Enzymes have a more immediate and specific effect, while cultures act more gradually to develop the overall cheese quality,” says Doug Willrett, director of enzymes at Danisco, Madison, Wis. “It takes the skill of a cheesemaker as well as the expertise of a culture/enzyme supplier to determine the most appropriate combination of cultures and enzymes to achieve the desired cheese product.”
Some of the latest developments and needs in the food industry have created new opportunities for enzymes or cultures and their effects in cheese, such as reducing the Maillard browning in mozzarella or the use of probiotic and prebiotic ingredients.
All told, the use of enzymes and adjunct cultures in cheesemaking continues to be a developing science in response to the industry’s need for increased functionalities and efficiencies. Knowing how to use enzymes and cultures effectively in cheese production is a complicated proposition, and suppliers of these ingredients continue to be the hinge pin to navigating through the various manufacturing considerations.
Faster, Faster
The traditional process of cheesemaking ensues when the bacteria in the starter culture begin growing by fermenting the lactose in the milk into lactic acid. In addition, the enzymes that are naturally present in these bacteria begin breaking down the milk protein, casein. One of the ways that suppliers of enzymes and cultures are beneficial at this initial stage of cheese product development is in choosing the appropriate starter culture.
 “The enzymes that digest the proteins are typically proteases and peptidases that are native to the composition of the bacterial cells in the starter culture,” says Terri Rexroat, Degussa Food Ingredients, Waukesha, Wis. “Some bacteria naturally have more of these protease and peptidase enzymes than other bacteria, so careful characterization is necessary to select the strains with the highest level of the desired enzymes.”
As the enzymes drive acidification and also coagulate the milk, cheese flavor begins naturally developing.
“The critical element is understanding how to drive the culture and culture adjuncts toward the flavor profile that the consumer desires. Progress in technology is allowing development of the detailed understanding of the biochemical pathways cultures and adjuncts have that contribute to flavor,” says David Burrington, director of marketing-dairy, at Chr. Hansen, Milwaukee. “This allows us to understand how to change the flavor profile of the cheese by intent rather than leaving it to chance.”
The need for faster ripening times in the last 20 years, an effect delivered by the addition of supplemental enzymes which speed natural flavor development, has changed the natural flavor development process in cheesemaking, creating a need for adjunct cultures to balance flavor.
“If you just used the starter cultures and coagulants [enzymes], there would be natural flavor development. But in today’s cheesemaking, there is a demand for faster production, which means flavor development needs to be accelerated as well. Adjunct cultures and supplemental enzymes help develop the cheese flavor more rapidly,” Willrett says. “However, faster cheese manufacturing can result in more bitterness in cheese, so the additional enzymes and adjunct cultures reduce the bitterness, and accelerate the natural flavor development in the final cheese product.”
Shortening the cheese aging period via accelerated ripening of cheese is caused by manufacturers’ desire to realize more productivity as well as to reduce cheese storage costs. And sometimes manufacturers add supplemental enzymes and cultures for more targeted flavor development.
“The adjunct cultures that contain the cheese ripening enzymes are added to the fluid milk in the cheese vat at the same time that acid-producing cultures are being added,” Rexroat says. “They don’t replace the acid-producing cultures because they are active during the post-cheesemaking ripening phase rather than during the primary cheese making process. The best approach to ensure selection of the best adjunct culture for the particular situation is to run several trial vats using varying adjunct cultures.”
The other purpose that supplemental enzymes and adjunct cultures have served in recent years is in reduced-fat cheeses, where the ratio of less fat to protein creates firmer cheese.
“One of the challenges with reduced-fat cheese products is flavor balance, because the fat/protein/water ratios are different,” Burrington says. “The complex interaction of components can yield products that are unbalanced flavor-wise and rubbery in texture. Careful attention to the culture can help in this regard; you want to avoid overly proteolytic cultures or enzymes.”
While enzymes can be used to affect the hydrolisis of the protein substrate in reduced fat cheese products to make them appear richer in taste and texture, thus far consumers typically find such products less appealing than their full fat counterparts.
“The trend over the last 25 years has been to reduce the time to produce cheese, resulting in more cheese from the same equipment. This increased productivity has been largely made possible by the advances in culture and enzyme technologies. But there is a limitation to how fast cheese can be made, and we may have reached a threshold with currently available technology,” Willrett says. “So we are continuing to refine the selection and development of cultures and enzymes which improve the quality of the cheese — in terms of acidification, flavor development and functionality.”
Atop Pizza
While the use of enzymes and cultures for more rapid cheese manufacture is a steady development, the mozzarella cheese market is experiencing a newly emerging need which echoes the trend for faster, faster, faster.
In the foodservice world, the time allowed for a pizza to bake is diminishing, as consumers expect their ’za to appear in shorter time increments than ever. The result is that higher temperature ovens are being employed to cook the typical pizza, and the Maillard reaction typical of mozzarella cheese is in need of an adjustment.
“Browning of mozzarella cheese during a pizza bake or other high heat processes is a result of the high level of the residual sugar galactose in mozzarella cheese,” Rexroat says.
The industry has been experimenting with adding adjunct cultures that utilize some of the galactose, which decreases the Maillard browning after cooking.
“The industry has achieved a ‘whitening’ effect in mozzarella by using adjunct cultures which ferment some of the galactose, but these cultures often do not reduce the galactose levels sufficiently to eliminate the excessive browning,” Willrett says. “We have developed an enzyme that acts quickly and specifically to utilize the free galactose in mozzarella cheese, eliminating the over-browning problem. The current challenge is how best to apply this enzyme during the cheese making process.”
Newest Research
Cultures are also used in fermented dairy products for certain results and benefits.
“For added shelf life in cultured dairy products, the most important step is prevention of the growth of contaminating bacteria,” Rexroat says. “This can be achieved by adding bacteria that are attenuated [inactivated] but that are still capable of contributing compounds called bacteriocins that can prevent the growth of specific undesirable bacteria.”
One of the newest developments in this arena is the use of cultures in some fluid milk products to extend shelf life.
“On the fresh dairy side, we offer bacteria protective cultures, which produce antimicrobials that help extend shelf life and improve the quality of the finished dairy products. These protective cultures and metabolites have become increasing popular because of their potential to replace many chemical preservatives,” Willrett says. “Consumers desire less exposure to chemical preservatives and are seeking products that are more natural.”
Of course, probiotic cultures are definitely an area that the dairy industry is keeping a close watch upon, as interest in probiotics is beginning to accelerate. Experts anticipate that soon consumer awareness of the health benefits provided by probiotics will reach a tipping point, and propel great demand for these cultures.
While probiotics will likely gain momentum as additions to the drinkable yogurts and cup yogurts initially, it also is possible to include probiotic cultures in many other dairy applications, including cheese.
Related to this anticipated growth in probiotics, prebiotics are finding their way into several foods and beverages. A prebiotic functions by selectively stimulating the growth of probiotics and other beneficial bacteria in the GI tract.
“The enzyme beta-galactosidase (lactase) can be used to produce the prebiotic galacto-oligosaccharide (TOS) from lactose,” Willrett says. “TOS is naturally found in human breast milk and is added to infant formula and other foods in various regions of the world to provide the desired prebiotic effect.”
Such advances in enzyme technology are good news for the world of dairy processing. In the past decade or so, the market value for whey has increased considerably, as research has demonstrated the vast health benefits conferred by whey proteins and various enzyme-produced peptide fractions. While such research has reinforced the value of proteins in whey, the value of the remaining milk carbohydrate, the lactose, has not seen a proportional increase in its overall value. Now the potential to transform some of the relatively low value lactose into higher valued prebiotics bodes well for the use of the milk carbohydrate.
At the same time, protease and pepidases enzymes have also been shown to be extremely useful in acting upon whey proteins to hydrolyze whey into different peptide fractions and subfractions, many of which confer interesting new functionalities and health benefits.
“For cultures, the future is especially bright for probiotics,” Willrett says. “As for dairy enzymes, opportunities for converting whey into higher value peptides and prebiotics paint a rosy picture for this technology and the dairy industry. I would place a big bet on that.”  
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