Corn fiber oil offers antioxidant properties, modulates cholesterol absorption.

The development of oxidative rancidity in products is a serious concern because the rancidity can lead to undesirable flavors and odors as well as potentially toxic lipid oxidation products. While there are many effective synthetic antioxidants that can be used to suppress lipid oxidation, there is strong consumer interest in using natural products as antioxidants.

Many compounds, such as corn fiber, confer health benefits in addition to their antioxidant activity. Corn fiber oil (CFO) contains high levels of three natural cholesterol-lowering phytosterol components: ferulate phytosterol esters, free phytosterols and phytosterol fatty acyl esters. Corn fiber is a low-value byproduct of the cereal grain wet milling process. Extracting corn fiber from the grain yields CFO, which consists of approximately equal amounts of oryzanol, b-sitosterol and linoleic acid. Oryzanol and b-sitosterol lower plasma cholesterol. They also possess antioxidant activity in model systems.

Scientists at Michigan State University evaluated the ability of CFO to inhibit lipid oxidation in a food system. The researchers incorporated CFO into ground turkey at levels of 0%, 0.25%, 0.50% and 0.75% (w/w). They examined the extent of lipid oxidation at 0 hour, 24 hours, 48 hours, 72 hours and 96 hours by measuring thiobarbituric acid reactive substances (TBARS). Oryzanol and b-sitosterol were also tested separately and together at levels equivalent to their presence in CFO.

There was a dose-dependent decrease in lipid oxidation as CFO concentration increased. There also occurred an average 40% inhibition of TBARS compared to the control. Neither oryzanol nor b-sitosterol alone or in combination matched the antioxidant activity of CFO. The inability of these compounds to reproduce the inhibitory effects of CFO could be the result of other active compounds present in CFO, or it could be caused by a solubility problem.

Incorporating 0.5% to 1% CFO into processed meat products is consistent with the recommended dietary levels of b-sitosterol and oryzanol that are required to reduce serum cholesterol totals. It appears from these studies that CFO can play an important dual role in human health as an antioxidant and as a modulator of cholesterol absorption.

Further information. Gale Strasburg, Department of Food Science and Human Nutrition, Michigan State University, 334 G. Malcolm Trout FSHN Building, East Lansing, MI 48824; phone: [phone]; fax: [phone]; email: [e-mail].