ABSTRACTThe retention of butylated hydroxyanisole (BHA), butylated hydroxy‐toluene (BHT) and mono‐tertiary butylhydroquinone (TBHQ) was investigated in model freeze‐dried systems designed to simulate a high lipid food. Model systems initially containing 400 μg antioxidant/g soybean oil were slowly frozen (‐22°C) or rapidly frozen (‐196°C) as slabs and freeze‐dried for 12.5 or 26.5 hr. respectively. Under these conditions TBHQ was retained to the greatest extent and BHA to a greater degree than BHT. On the average, slowly frozen samples retained 32, 27 and 16 TBHQ, BHA and BHT, respectively, which was about 1.2 times higher than rapidly frozen samples. It was found that the retention of BHA and BHT was greatly influenced by the final moisture content of the freeze‐dried system in the range between 1‐5 moisture. TBHQ retention, however, was found to be less dependent on the final moisture content of the freeze‐dried system over the same moisture range. The effect of extending the normal freeze‐drying time (12.5 hr) of slowly frozen samples on antioxidant retention was determined. When the normal drying time was doubled BHA and BHT were completely removed and TBHQ content was reduced by an additional 19. Antioxidant retention was interpreted on the basis of current mechanisms to explain the retention behavior of volatile organic substance
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