Experimental cookery

Protective action of green light. Coe and Le Clerc compared the inhibiting effect of excluding all light, using only green light of 490 to 580 m/x wave length or 4900 to 5800 Angstrom units, with the effect of several antioxidants, including maleic acid and pyrogallol, upon oxidation of fats. They report that oils or fats stored at low temperatures and with all light excluded remained fresh longer than if treated with antioxidant or packaged in green wrappers and exposed to light at room temperature. Packaging in green glass or opaque wrappers was more effective in keeping fat fresh than the addition of the antioxidants. Green glass or opaque wrappers which exclude all light except the aforementioned wave lengths are suitable for packaging nuts, potato chips, or food products for display purposes. Ketonic rancidity. Davies states this type of fat spoilage is caused by molds which attack the short-chained saturated fatty acids, the decom- position products producing disagreeable flavors. Since butter and coconut oil are the principal fats which contain short-chained acids in the glycerides, most ketonic rancidity is confined to these fats. Effect of light, heat, and air. It has been known for years that exposure of fats to light, heat, and air is deleterious to keeping the fat fresh. Greenbank investigated the relative effect of each of these factors. He concludes that in the presence of air, light is the most powerful accelerator, and moisture and heat follow \n the order given. "This conclusion holds only for lower temperatures." A vacuum may retard oxidation but not prevent it. Triebold and Bailey found that all hydrogenated shortening samples stored in unopened containers showed induction periods of approximately the same length. Samples from containers once opened and then restored 554 FATS AND OILS had shorter induction periods. A lard sample stored in the laboratory for a year with air excluded appeared in as good condition at the end as at the start of the experiment. They emphasize the practical importance of pre- venting undue exposure of shortenings to air and decreasing the surface area of the fat exposed to air. Home storage of fats and oils. All the work on development of rancidity in fats and oils indicates that the fat should be stored so that light is excluded, at a low temperature, and with as little exposure to air as possible. For farm storage of lard, when 5, 10, or more gallons are stored in one container, the light should be excluded and Triebold and Bailey's results suggest a tall narrow container, rather than a wide flat one, for the former exposes a smaller surface of the fat to the air. When lard is removed from these containers it is preferable to remove a level layer rather than to dig out the center portion. Changes in Fats during Cooking Processes Masters and Smith have investigated the character of the changes in fat during cooking. They state that the changes occurring in the fat in cooked pastry are slight, unless the pastry is very thin or over-cooked.