Silicones (polydimethyl siloxanes) greatly increase the oxidative stability of an edible oil at high temperature. The effect is demonstrated here, using a thin layer chromatography technique to follow the oxidation of the oil. The minimum fully effective concentration corresponds to a monolayer of silicone on the air‐to‐oil surface. Using an atomic absorption technique, estimates have been made of the amount of silicone picked up on food fried in a silicone‐containing oil. When potato chips are fried in an oil containing 2 ppm silicone or more, the silicone content of the used oil is reduced to below 1 ppm and the surplus is taken up by the potato chips. In view of this pickup effect, and because only a very small amount of silicone is required to protect the oil, it is not desirable to use the silicone at levels higher than 2 ppm. Silicones should therefore be added in a controlled manner by the frying oil manufacturer.

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Changes in composition produced in monounsaturated triglycerides during the course of interesterification, before full randomization is achieved, have been followed by using thin-layer chromatography. Results indicate that intraesterification, in which interchanges take place between positions on the same molecule, occurs at a faster rate than the general randomization which results from intcresterification.The reaction is found to proceed according to the expression log a a t, where 'a' is the proportion of fatty acid components not changed in position by the reaction. This expression is of general application to triglyeeridc interesterifications and provides a basic equation in terms of which the effects of temperature, catalysts, and other ex-I)eriInental eon(litions can be studied.

The article contains sections titled: 1. History 2. Properties of Margarine 2.1. Subjective Properties 2.2. Objective Properties 2.2.1. Color 2.2.2. Gloss 2.2.3. Melting Properties 2.2.4. Penetration 2.2.5. Drop Size 2.2.6. Salt Release 2.2.7. Keeping Properties 3. Composition 3.1. The Fat Phase 3.1.1. Choice of Fat Blend Components 3.1.2. Preparation of Fat Blends 3.1.2.1. Refining 3.1.2.2. Hardening 3.1.2.3. Interesterification 3.1.2.4. Fractionation 3.2. The Aqueous Phase 3.2.1. The Aqueous Phase in Conventional Margarines 3.2.2. The Aqueous Phase in Low‐Fat Spreads 3.3. Emulsifiers 3.4. Minor Components 4. Processing 4.1. Churn Process 4.2. Votator Process 5. Specialty Margarines and Shortenings 5.1. Pastry Margarines 5.2. Frying 6. Packaging 7. Economic Aspects