Sulforaphane in broccoli-based matrices: Effects of heat treatment and addition of oil

There is significant interest in developing high sulforaphane-containing broccoli-based ingredients as sulforaphane has potential for reducing the risk of a number of diseases. Glucoraphanin in broccoli is converted to sulforaphane by myrosinase when the plant tissue is disrupted. The instability of sulforaphane at high temperature and in aqueous environments presents challenges for developing sulforaphane-containing ingredients. Variations in heat treatment conditions of broccoli suspensions, pH, oil addition and storage conditions influenced the level of sulforaphane. The sulforaphane content of aqueous broccoli suspensions as a function of pH (pH 4.0, 5.0 and 6.0) after a heat treatment (60 degrees C/5 min) and holding for 4 h at 25 degrees C were examined. A pH of 5 was optimum for production of sulforaphane. The addition of oil to broccoli suspensions prior to freeze drying retarded the rate of degradation of sulforaphane during storage of powders. There was little difference between degradation rate of sulforaphane in (broccoli-oil) powders made from pH 5 or pH 6 (broccoli-oil) emulsions. There are significant hurdles for the development of high sulforaphane broccoli powders for use as functional food ingredients or supplements.