When buying cooking oil, you often hear the phrase “this is hot pressed oil” or “this is cold pressed oil”. What is the difference between two making methods of cooking oil? Let’s take a look.
First is cold pressed, method of cold pressed oil refers to oil without heating or before squeezing, under the condition of low temperature into the oil press, generally in less than 60 ℃ under the environment of processing. The raw materials of cold pressed oil must be selected, otherwise the quality of cold pressed oil will be affected. The extracted oil is of low temperature and low acid value. In general, no refining is required. After precipitation and filtration, the refined oil is obtained.
The cold-pressed oil retains the natural flavor and color of the oil, completely preserves the physiological active substance in the oil, has low degree of protein denaturation, and is easier to use the protein comprehensively. Generally speaking, the smoke point of cold pressed oil is low, water content is not stable, unfavorable long-term storage. Cold pressed oil color is good, the color is relatively light. Cold pressed oil does not froth when eaten, but is less fragrant than hot pressed oil.
Hot -pressed oil, that is, oil is cleaned and broken before oil extraction, and then heated at high temperature to make a series of changes inside the oil: damage oil cells, promote protein denaturation, reduce oil viscosity, etc., so as to be suitable for oil extraction and increase oil yield. However, the crude oil extracted from oil treated at high temperature is darker in color. High temperature oil extraction results in great nutrient loss in the process of oil extraction (vitamin E, sterol, carotenoid, etc.), resulting in waste of resources. Generally, screw oil extraction machine is needed in hot rolling.
Hot pressed oil has a pure taste and aroma, especially those rich in oil like sesame and peanut. The disadvantage is that the frying pan will be foamed and silted when it is not processed, which needs to be filtered by the oil filter.
Although cold-pressed oil is original and is a healthy choice for life, it is not good for some oil crops to be cold-pressed. Although cold pressing retains the original good nutrients in oil crops, it also preserves some of the bad ingredients in oil.
Take soybean, high erucic acid rapeseed, cottonseed, peanut, and sesame as examples: soybean oil contains bettiness, high erucic acid rapeseed oil has spicy flavor, cottonseed oil contains gossypol toxin and aflatoxin in spoiled oil can only be removed by refining. The fragrance of sesame oil and peanut-scented oil can only be obtained through hot pressing process. Therefore, when choosing edible oil, we should pay attention to the types of edible oil, and buy it according to our own demands and actual conditions.