Question

How we can Identify physicochemical properties and specification of triacylglycerol polymers which are present in heat-processed vegetable oils?

Answer 1

At elevated temperatures, oils will change significantly due to the many chemical and physical reactions which occur, such as oxidation, hydrolysis, cyclization, isomerization and polymerization. When frying, oil also decomposes into a variety of volatile compounds and monomeric and polymeric products, which are
capable of influencing not only the sensory and health quality, but also the shelf life of the fried product. However, free radicals, trans-fatty acids,conjugated linoleic acids and some oxidized volatile products (acrolein and other α, β-unsaturated aldehydes) commonly formed during edible oil degradation, are known to be responsible for the off-flavor, reducing the shelf-life of edible oils and may further cause health problems.

Physical changes in oils that occur during frying and heating include increased viscosity, darkening in color, and increased foaming as frying time continues. At the same time, the smoke point of the oil decreases. The frying operator may not notice these effects
until the oil has been used for prolonged periods of time. Specific methods exist to measure degradation processes and products quantitively: free fatty acids, carbonyl compounds, and high molecular weight products will increase with increased frying time and can be measured chemically or by chromatography.