Utilization of Bamboo Choacoal to Food Processing and Cookery

Part I Effects of Bamboo Charcoal on Oxidative Stability of Frying Oil

Abstract

We examined the antioxidative effect of the addition of bamboo charcoal on frying oil. Bamboo (Phyllostachys pubescens) was carbonized at 500, 800, and 1100°C in an electric oven to make bamboo charcoal, referred to hereafter as bc500, bc800 and bc1100, respectively, The higher the oven temperature, the lower was the electric resistance of the charcoal. The surface area of the charcoal was 4.62, 314.21 and 0.79m²/g, for bc500, bc800 and bc1100, respectively. The anisizine value (An V) measured as the indicator of the oxidation of the frying oil to which was added 20% charcoal (w/v) was 151.4±4.5, 54.7±2.9 and 59.1±6.9 for bc500, bc800 and bc1100, respectively, after heating at 180°C for 6h, while that without charcoal was 150.2±1.7. A more detailed examination revealed that antioxidative effect of 1% added oil was not observed, but manifested significantly in both 5 and 10% added oil. The frying oil inside the charcoal was less oxidized than the oil outside the charcoal, the An V value, 83.3±0.6 and 213.6±4.4, respectively, after heating at 180°C for 6h, while that without charcoal was 271.1±3.7. The crashed charcoal (0.5-1.0mm in diameter), in which many small holes were observed by electron micrography, indicated stronger antioxidative activity than smaller or larger diameter samples. From these results, the high antioxidative effect of the addition of bamboo charcoal (bc800) on frying oil was considered to be due to chemical adsorption to the large surface area of the charcoal, and to less oxidation of the oil inside the charcoal.