Virginia Polytechnic Institute and State University

UPDATES AT VIRGINIA TECH

Apology for Last Month

Last month's Dairy Facts newsletter contained an article entitled “ E. coli in Raw Milk”. It has been brought to our attention that the title was misleading because the dairy in question was later released from the recall – no positive tests for E. coli were found. The article was in progress when these results were reported, and although the article was altered, the original title was never updated. This was an oversight on our part, and we apologize for the error.

Dairy Products Evaluation Team

The Virginia Tech Dairy Judging Team competed in the 85 th Annual Collegiate Dairy Products Evaluation Contest from October 29 to October 31 in Chicago , Illinois . There were 19 universities competing this year. The undergraduate team, consisting of Jessica Ruedisueli (New Jersey), Nelmarie Naude' (South Africa), and Jarret Wright (Virginia), scored 15th overall with a high of 7 th in Butter. Our graduate students did very well, with Dina Romano (Illinois) coming in 2 nd in butter and 9 th in cheddar cheese. Priti Parikh (India) ranked 5 th in milk, 7 th in ice cream, and 8 th in butter. There were 57 students in the undergraduate competition and 17 at the graduate student level. The students learned a lot this year. All worked very hard and represented Virginia Tech very well. Dr. Susan Duncan was the coach, Walter Hartman was assistant coach, and Mark Kline served as assistant graduate student coach.

The contest is designed to help students learn practical information about the relationship of sensory characteristics in dairy products to raw milk quality, processing, packaging, and quality changes occurring from spoilage. The contest involves evaluating 6 dairy product categories; Milk, Cottage Cheese, Strawberry Yogurt, Cheddar Cheese, Butter, and Vanilla Ice Cream. These products are first certified by industry judges for quality. The college coaches and industry judges then discuss the scores and come to a consensus. The students then have to try to match the official evaluations. The team was sponsored this year by Food Processing Suppliers Association, American Dairy Science Association, USDA, Westover Dairy , Virginia Dairy Industry, and Virginia Dairy Technology Society.

HOT TOPICS AND DAIRY ISSUES

Dairy Products May Control Blood Pressure

Two recent research studies have looked at how dairy (calcium) intake effects blood pressure. French men between the ages of 45 and 64 participated in a study that surveyed cardiovascular risk, three-day food records and blood pressure measurements. Of the 912 men who participated, those with the highest dairy intake were found to have significantly lower systolic blood pressure than those who consumed lower amounts of dairy products. Systolic blood pressure is a key predictor of cardiovascular disease. Results were similar when calcium intake was examined and blood pressure reduction was most significant when intakes of both calcium and dairy were high. Researchers concluded that dairy and calcium intakes are both significantly and independently related to reduced systolic blood pressure, and that bioactive components in dairy foods may have been responsible for this finding.

The second study was recently published in the Journal of the American Heart Association . Of the 4,797 participants, those who consumed three or more servings of dairy foods a day had significantly lower systolic blood pressure than those who consumed less than half a serving a day. These results did not take calcium intake into consideration, and most significant decreases in blood pressure corresponded with participants who consumed less saturated fat. Studies like these help reinforce the value of including low-fat dairy products, such as milk, cheese and yogurt, in the daily diet to help lead a healthier lifestyle.

Flavored String Cheese

The Wisconsin Center for Dairy Research (WCDR) developed a project that involved incorporating sweeteners and flavors into cheese. The target audience is children, or perhaps mothers who want to include a healthy dairy snack in their kids' lunch boxes. The WCDR cheese applications group first worked with string cheese and then made processed cheese with flavors that kids go for – bubble gum, watermelon and green apple.

The group started by producing a strawberry-flavored string cheese. Given the pH range of string cheese, the cheese specialists were concerned about the pH ranges needed to produce a full strawberry flavor. Another concern was the chance that the thermophilic starter culture would ferment the sweeteners, possibly causing late gas formation in the cheese package. Incorporation points as well as the issue of retaining strawberry flavors in the cheese matrix were other variables the researchers considered.
To answer these questions, the group ran four strawberry-flavored string cheese trials that used different methodologies to incorporate sweeteners and strawberry flavoring. They were aiming for a cheese that tasted like strawberry yogurt but acted like string cheese. The first trials showed that the string cheese texture was better when standardizing milk to a casein-fat ratio matching regular string cheese. Thermophilic cultures did not seem to produce more gas in the packages than did the mesophilic cultures.
The researchers found that adding all ingredients to the stirred curd—at the time of salting and ingredient addition and before the molding step—was the best way to incorporate them into the cheese matrix. They were able to gauge the level of sweetener (sucrose) needed, as well as artificial sweetener (sucralose), to bring out flavor and sweetness in the string cheese. In addition, they were also able to verify that adding an emulsifying salt in addition to sodium chloride helped to incorporate the sweetener and flavor into the string cheese as opposed to adding sodium chloride only.
Although many questions were answered by trials, the researchers learned that the pH range of string cheese (about 5.10 to 5.30) limited the expression of strawberry flavor. When malic or citric acid was added, more strawberry flavor was noted as well as a nice aroma. However, due to the lower pH, these acids had a detrimental effect on the final string cheese texture; it was pasty and had little or no string. When no acid was added, the texture of the string cheese was good with nice string, but very little strawberry flavor.
The group switched to trials using flavors detectable at pH ranges similar to those of the string cheese. The manufacturing parameters developed for the strawberry-flavored cheese were used to make cotton candy, bubble gum, green apple and banana-flavored cheese. Colors were added to the cheese milk to give vibrant colors. Although they had no effect on the cheese manufacturing process, the colors, as expected, had an effect on the color of the whey produced. Adding color directly to the cheese after mixing might be worth a try. Informal tasters easily identified all the cheese flavors, particularly cotton candy and bubble gum.