Kayanush J. Aryana, Charles Boeneke and Ronald Gough

Several new food products or ingredients have been identified as contributing to human health. Including such ingredients in manufactured dairy products would improve their health-giving benefits. LSU AgCenter researchers are testing how the incorporation of these health-beneficial ingredients in dairy products affects physico-chemical and sensory characteristics.

Replacing milk fat in Cheddar cheese
Milk fat is high in saturated fatty acids. Saturated fats contribute to gradual blockage of the arteries, reducing blood flow. The omega-3 fatty acids, on the other hand, are known to have beneficial effects on cardiovascular diseases by lowering cholesterol and triglycerides, lowering blood viscosity and decreasing blood pressure.

The focus of one research project is to replace the saturated fatty acids in a milk product, Cheddar cheese, with omega-3 fatty acids. One source of omega-3 fatty acids is a commercial product called OmegaPure, a refined fish oil that can be added to a variety of foods.

Another commercial product that can replace saturated fatty acids in milk products is Benecol. This is a cholesterol-reducing product, available to consumers at grocery stores, that includes a patented ingredient, plant stanol ester. We also tested this product in Cheddar cheese and evaluated both products with different ratios of milk fat.

Results of the study are as follows:

• Benecol and OmegaPure did not affect the overall composition of the cheeses.
• There were no differences in the lightness values of the cheeses made with Benecol and OmegaPure compared to the control. The full-fat cheeses made with Benecol were more yellow than the full-fat control, which would be desirable in a product like Cheddar cheese.
• Benecol and OmegaPure did not affect the pH of the cheeses at low and medium levels of usage. At the high usage level, the two products lowered the pH of the cheeses.
• Benecol and OmegaPure did not affect the protein profile of the cheese.

The aerobic bacterial counts appeared to increase from two to four months and then declined at six months in both the low-fat and the full-fat cheeses made using Benecol and OmegaPure.

When used at 25 percent in Cheddar cheeses allowed to age for 24 weeks, Benecol resulted in textural qualities comparable to the control. Benecol did not adversely affect the flavor in full- and low-fat cheeses. OmegaPure improved texture in the full-fat cheeses but adversely affected flavor.

Yogurt and folic acid
Folic acid is important to human health. Folic acid deficiency is a factor responsible for neural tube defects in humans. Low levels of folic acid have also been linked to coronary heart disease. Low plasma folic acid concentrations have been reported to be a risk factor for stroke. An inverse correlation has been observed between colorectal cancer and dietary folic acid.

Folic acid cannot be synthesized by humans or mammals and must be provided through diet. Good sources of folic acid are green vegetables such as asparagus, spinach, broccoli, turnip greens and brussels sprouts and by organ meats such as liver and kidney. Dairy products such as yogurts, however, are not good natural sources of folic acid. Folic acid is a water-soluble vitamin, and yogurt is a high-moisture, low-caloric, semi-solid dairy food that can be consumed as a snack or dessert. Adding folic acid during yogurt manufacture would result in a healthier product.

LSU AgCenter researchers tested adding folic acid at various concentrations and various stages in plain and flavored yogurts. The results of incorporating folic acid into plain yogurt included:

• No changes in yogurt composition.
• No changes in pH or acidity.
• No differences in protein or peptide profiles.
• No differences in syneresis – the separation of liquid from the gel – when comparing stages of addition, concentrations and time of storage.

Yogurt viscosity was not affected by folic acid incorporation or by storage time. Pasteurization had no effect on the lightness of the yogurts. Lightness values were lower at week 3 compared to weeks 1 and 5. Flavor was not affected by the concentration of folic acid or stage of addition. Flavor was the highest at week 1, dropped at week 3 and increased at week 5. Body and texture scores for yogurts averaged 4 on a scale of 1 to 5.

In addition to plain yogurt, lemon- and strawberry-flavored yogurts were produced. Some differences were observed between plain and flavored yogurts.

Folic acid concentration had significant effects on the viscosity of both lemon- and strawberry-flavored yogurts. Lower viscosities for lemon yogurts were recorded when folic acid was added after pasteurization. Viscosity of lemon yogurts increased at week 3, compared to weeks 1 and 5; viscosities of strawberry yogurts were not affected.

Acidity and syneresis of strawberry yogurts were not affected by folic acid concentration or stage of addition, and syneresis was not affected by storage time. The level of folic acid concentration was not significant for the lemon-flavored yogurts.

The stage of production when folic acid was added did not affect the flavor of lemon and strawberry yogurts; however, the level of folic acid and storage time showed significant differences in mean flavor values of the flavored yogurts. Average body and texture scores were fairly high, recording a 4 out of a 5 for flavored yogurts fortified with folic acid.

Conclusions
Incorporating OmegaPure and Benecol in Cheddar cheese is favorable at a low concentration of 25 percent fat content. At high concentrations, however, the addition of these products results in a harder cheese with a markedly altered flavor.

Folic acid can be added to yogurts without adversely affecting product characteristics. Since there were no significant losses of folic acid during pasteurization, folic acid can be added before pasteurization, enabling processors to follow the federal Food and Drug Administration’s Hazard Analysis and Critical Control Point requirements in keeping with the production of safe dairy foods.

Future research
Production of functional dairy foods continues to be a primary focus of dairy products research at the LSU AgCenter. Projects include fat-free, no-sugar-added ice cream, yogurts fortified with various minerals, vitamins and fibers, and development of new dairy products with added health benefits.

Kayanush J. Aryana and Charles Boeneke, both assistant professors; and Ronald Gough recently retired professor, Department of Dairy Science, LSU AgCenter, Baton Rouge, La. 

(This article was published in the summer 2004 issue of Louisiana Agriculture.)