Effect of grinding methods on the retention of black pepper volatiles

Black pepper (Piper nigrum L) was ground at four different feed temperatures viz., 40 degrees C, ambient (24 degrees C), 10 degrees C and -120 degrees C, using hot or chilled water circulation through the grinder jacket or direct injection of liquid nitrogen (LN,) into the mill along with the feed. The volatile oil content of the product indicated that chilled water and LN(2) cooled conditions retained almost same quantity of volatiles (3.56 ml/100g and 3.60 ml/100g, respectively) and powder fineness was greater in the case of the latter. The gas chromatographic analysis of the oil showed higher retention of monoterpenes under cryogenic (LN(2)) and low temperature (chilled water) grinding conditions than under ambient and high temperature grinding conditions.