Vacuum frying Machine oil in the process of frying, water constantly released from food to hot oil, this process is equivalent to steam distillation, oil volatile oxidation products removed. The released moisture plays the role of stirring oil and accelerating hydrolysis, as food itself or food interacts with oil to produce some volatile substances.
As a result, the oxidative stability of the newly blended fats of the vacuum frying machine is very different from the original fried fats. In the process of frying with a vacuum frying machine, deep-frying oil has undergone drastic chemical and physical changes. The formation and decomposition of hydrogen peroxide produces saturated and unsaturated aldehydes, ketones, hydrocarbons, lactone, alcohols, acids and esters and other volatile compounds; due to the combination of heat and oxidation of free radicals to produce two poly and poly acid and two poly and poly Glycerin, the result of polymerization results in the oil viscosity increased significantly; hydrolysis of triglycerides to produce free fatty acids, these changes make oil viscosity and free fatty acid content increase, color darkening, iodine value and surface tension drop, refractive index change, the formation of foam tendency increased.
Therefore, during the frying process of vacuum frying machine, oil and food have undergone great physical and chemical changes, some changes have given the desired sensory quality of fried products, some changes are harmful.