Vegetable sources of cancer chemoprotective agents have been identified which are extraordinarily rich in glucosinolates, metabolic precursors of isothiocyanates. The product of the process is the most active and industrially most important member of the vitamin E group. In contrast, when the slide door is open, the protrusion that is accommodated in the groove is capable of moving vertically and horizontally. Another variety is a continuous set of wave guides bordering the flow path. 5 weight percent total saturated fatty acids. To cool part of the casing, the casing includes means for diverting a second portion of the air flow away from said at least one heater, and second channel means for conveying the second portion of the air flow along an internal surface of the casing.