A novel approach improves shelf life of sterol--containing vegetable fat spreads.

Coronary heart disease (CHD) annually accounts for more deaths than any other disease, including all forms of cancer combined. Although there may be many causes that trigger CHD, a high plasma cholesterol level has been established as one of the major risk factors.

In the United States, about 98 million people have borderline to high plasma cholesterol levels. Studies indicate that lowering plasma cholesterol levels may reduce the incidence of first heart attacks, the overall number of deaths from heart disease and the need for heart surgery.

Phytosterols--plant sterols--are known to reduce serum-total and low-density lipoprotein cholesterol concentrations in our blood by lowering intestinal cholesterol absorption. So, it appears that consuming foods containing phytosterols provides health benefits. Yet, despite their beneficial health effects, phytosterols are very difficult to formulate into foods, due to their insolubility in water and their limited solubility in fats and oils.

In the 1980s, scientists developed the technique of esterifying phytosterols with unsaturated fatty acids to increase their fat solubility and to make it possible to incorporate them into vegetable fat spreads. Unfortunately, phytosterol esters are prone to rancidity, and the resulting fat-based food products have a limited shelf life.

To improve the shelf life of vegetable fat spreads, scientists at Forbes Medi-Tech have developed a new formulation that involves incorporating a combination of phytosterol esters and free sterols. Experimental results indicate that free phytosterols exhibit greater protection against the oxidation of vegetable fat spread during storage, compared to their esterified counterpart.

In addition, adding free phytosterols to vegetable oils reduces the extent of polymerization and the potential for changes in molecular weight, while improving color and viscosity. At the same time, when incorporated into the fat spread, free phytosterols provide significant texturizing properties and subsequently reduce the amounts of hardstock needed during processing.

In margarines, Forbes Medi-Tech has been using less free phytosterols than esters, but the approximate percentages are proprietary information. In milk, yogurts and other products the company has been using only the free phytosterol form.

Phytosterols have antioxidant activity, which could explain the stabilizing effect on margarines and oils. They also have antimicrobial activity. The mechanism of action here is not clear. Forbes has a patent covering the stabilizing effects of phytosterols. Potentially, these stabilizing properties could have value in allowing an extended shelf life but, to date, the company has not commercialized this attribute.

Further information. David Stewart, Ph.D., Vice President, Regulatory Affairs, Forbes Medi-Tech Inc., Suite 200, 750 West Pender St., Vancouver, BC V6C 2T8 Canada; phone: [phone]; fax: [phone]; URL: www.forbesmedi.com.