Investigations into the origin of chloroanisoles causing musty off-flavor of raisins

The formation of chloroanisole in commercially processed and nonprocessed dried-on-the-vine (DOV) raisins under sterile, nonsterile, and low-moisture conditions was determined. The chloroanisoles of raisin samples were steam-solvent extracted using a modified Likens-Nickerson glass distillation apparatus and the concentrated extracts analyzed by gas-liquid chromatography and mass spectrometry. Processed raisins with low water activity (Aw) of 0.48 or 0.80; formed 2,4,6-trichloroanisole (TCA) when incubated during a 3-4 week period. TCA was formed by raisins partially sterilized with propylene oxide or completely sterilized with hydrogen peroxide. Nonprocessed DOV raisins incubated at an Aw of less than or equal to 0.80 also formed TCA. Although the amounts of TCA formed in raisins vary greatly from batch to batch, it is demonstrated that sterilized raisins formed TCA under low water activity nonconducive for microbial activity.