Carnosine Concentration and Antioxidant Activity in Animal Protein Meals

By Annel K. Greene, PhD
Center Director, Clemson University
Animal Co-Products Research and Education Center

Dr. Paul L. Dawson, professor of Food Science and Human Nutrition and a member of the Clemson University Animal Co-Products Research and Education Center (ACREC), is conducting a research project to determine the carnosine content of animal protein meals. Carnosine is a water-soluble dipeptide that has been proven to be a powerful antioxidant. Composed of the amino acids beta-alanine and histidine, carnosine is naturally present in skeletal muscles as well as in organs such as the brain and skin. Research has indicated that carnosine may be used for a variety of antioxidant activities. Medically, it has been correlated with anti-aging and disease prevention as well as tissue regeneration after injury, radiation, or other damage to cellular membranes.

The objective of Dawson’s exploratory research is to determine the content and biological activity of carnosine extracted from rendered poultry products. Because carnosine is a water-soluble peptide, extraction procedures are easily accomplished. The overall goals of the project are to derive carnosine from animal protein meals for use as an antioxidant in rendered products and to catalog the concentrations of carnosine in poultry meals so the products can be so labeled. It is believed that high levels of carnosine could become a significant value-added selling point for animal protein meals over vegetable proteins.

In preliminary studies, Dawson and graduate student Paljinder Manhiani determined the levels of carnosine in raw poultry tissues using two methods to quantitate carnosine. The first is a rapid screening method that is less expensive to perform but is less sensitive. The second method involves use of liquid chromatography and is more expensive and time-consuming, but yields more sensitive results. Dawson also measured antioxidant capacity using three different assays that are standard tests used in determining antioxidant properties in foods and feeds. The first assay measures true antioxidant activity by measuring the free radical scavenging ability. The second assay involves metal binding or chelating ability, while the third method measures the active oxygen scavenging capacity.

The researchers determined that chicken brain was the richest source (6.1 milligrams [mg]/gram [gm]) of carnosine followed by breast (5.4 mg/gm) and gizzard (5.4 mg/gm). The chicken tail section contained the least available amount of carnosine (1.5 mg/gm) and the heart contained no carnosine. Upon measuring the metal chelating activity, the extracts from the head had 32.29 percent metal chelating activity and the extracts from the tail section were the second highest with 28.77 percent metal chelating activity. Higher metal chelating activity results indicate a better antioxidant capacity of the product. Earlier studies on muscle extracts had indicated that the metal chelating activity for breast was 32.24 percent and for thigh was 14.95 percent. In measuring total antioxidant activity, water extracts from chicken breast muscle were 50.4 percent and from thigh muscle were 33.1 percent. In comparison, pure carnosine has a total antioxidant activity of 76 percent. Recommended human doses are in the range of 50 to 100 mg. Veterinary uses can be readily envisioned and, thus, the potential yield from animal co-products could supply a large market.

Dawson and his graduate student are continuing their work using animal protein meals as a source of carnosine. The significance to the industry could be the extraction of antioxidants from animal protein meals for use back into rendered animal co-products. In addition, with wide antioxidant properties, the application of carnosine as a nutraceutical could increase value in the pet food and animal feed industries. Carnosine also has been suggested for use in eye drops, cosmetics, and skin lotions. An acetyl derivative of carnosine even has been studied for non-surgical treatments of cataracts. Recovering a high value product such as carnosine from animal protein meals could generate additional revenue for the rendering industry. Although this research is targeted toward poultry products, further research could be suggested for studying carnosine content from other rendered products as well. ACREC is very proud to have Dawson and his team working on finding value-added products from rendered animal meals.

Dawson obtained his doctorate from North Carolina State University and has become a leading expert in food quality and safety. He is a member of the Poultry Science Association, Institute of Food Technologists, American Chemical Society, International Association of Food Protection, and American Society of Agricultural Engineers. Dawson is an associate editor of Journal of the Science of Food and Agriculture, and was honored in 2006 by the Clemson University College of Agriculture, Forestry and Life Sciences with the Graduate Teaching Award and in 2009 with the Godley-Snell Agricultural Research Award. His work has been featured in newspaper articles and on various radio programs.

ACREC Solutions – June 2010 RENDER | back