Antioxidant System for the Preservation of Vitamin A in Ultra Rice

Abstract

Background Ultra Rice grains are micronutrient-fortified, extruded rice grains designed to address specific nutritional deficiencies in populations where rice is a staple food. Vitamin A and some of the B vitamins, as well as iron and zinc, are target nutrients for fortification through Ultra Rice technology. Vitamin A is sensitive to degradation. Therefore, the original Ultra Rice formulations included stabilizers, some of which were not approved as food additives in all of the receiving markets. Objective To develop a new antioxidant system for improving vitamin A storage stability in Ultra Rice grains, while complying with international food regulations. Methods Ten formulations were prepared containing various combinations of hydrophilic and hydrophobic antioxidants, as well as moisture stabilizers. Accelerated vitamin A storage stability tests were conducted at 25°, 35°, and 45°C with 70% to 100% relative humidity. Results The most stable samples contained one or more phenolic antioxidants, a water-soluble antioxidant, and stabilizing agents. The best results were obtained by using butylated hydroxyanisole (BHA) in combination with butylated hydroxytoluene (BHT) as the hydrophobic antioxidants and ascorbic acid as the hydrophilic anti-oxidant. Citric acid and sodium tripolyphosphate (STPP) were used to chelate metal ions and to stabilize moisture, respectively. The best formulations retained more than 85% and approximately 70% of the added vitamin A at 25° and 45°C, respectively, after 24 weeks storage. Conclusions The best antioxidant system, composed of generally accepted food additives, improved vitamin A stability while reducing the price, thus greatly improving the commercial viability of Ultra Rice grains for use as a rice fortificant.