Improve cheddar cheese quality.

Cheddar cheese has long been a favorite among cheese lovers. Scientists at the Minnesota-South Dakota Dairy Foods Research Center (University of Minnesota, Department of Food Science and Nutrition, 1334 Eckles Ave., St. Paul, MN 55108) are investigating ways to improve the flavor and quality of cheddar cheese by adding non-starter lactic acid bacteria to the cheesemaking process.

The bacteria are of interest to researchers and cheesemakers because their numbers increase as cheese ripens, corresponding to the development of both positive and negative flavor and texture attributes. It's possible to improve on cheddar flavor notes with a greater understanding of the types of strains that have a positive impact.

Scientists studied the bacteria in premium commercial cheddar cheese to increase their understanding of its positive role in determining cheddar cheese flavor and quality. A population of non-starter lactic acid bacteria in three-month ripened cheddar cheeses was characterized and identified to determine individual roles in cheddar cheese flavor. Investigators found the dominant non-starter lactic acid bacteria in cheddar cheese are from the genus Lactobacillus.

By adding lactobacilli adjuncts to cheddar cheese, researchers found an increase in proteolysis and improved flavor intensity. Because of the accepted role of proteolysis in flavor development, the proteolytic ability of the bacteria is an important phenotypic characteristic.

In addition to testing commercially-prepared cheddar, researchers made cheddar at their pilot plant using whole milk. They followed standard cheddar cheesemaking procedures. Four sample treatments were evaluated after three months and six months of ripening. Two of the cheese matrices were treated with single strains of a non-starter lactic acid bacteria isolate. One was treated with a blend of two isolates, and one was a control with no adjunct added.

A taste test comparing the samples to a premium-grade commercial cheddar found that the matrix treated with a blend of two strains-lactobacilli and lactococci-was significantly more flavorful and less bitter than the control. Adjunct lactobacilli may suppress the growth of unwanted bacteria, improving overall quality and consistency.

Researchers recommend certain procedures that processors should follow. From high-quality commercial cheese produced in your facility, use selective media and plating techniques to isolate the non-starter bacteria. Characterize those bacteria for desirable metabolic traits for cheese ripening, such as homofermentative, non-coagulating, non-proteolytic, significant peptidase activity, and non-D lactic acid-producing traits.

Use genetic fingerprinting techniques, such as PCR technology, to identify the most promising non-starter organisms. Select some of these non-starters to see if they are appropriate for cheese production, can be grown to high numbers and can be added to cheese milk as adjuncts. Determine if the cheese made with these adjuncts is of high quality and contains significant numbers of the added adjunct. Determine if the adjunct culture keeps unwanted non-starters from dominating the cheese during ripening.

Further information. Joe Warthesen; phone: [phone]; fax: [phone]; email: [e-mail].