You can't simply say it’s good or bad. You have to compare them first.
First of all, the two processes are different. The cold press oil is put into the cold press without heating or low temperature before the oil is pressed. The oil extracted by the cold press oil expeller has a lower temperature and acid value. Generally, it does not need refining. After precipitation and filtration, the product oil is obtained. But most of the edible vegetable oils in our daily life are hot oil press machine, that is to say, the oils are cleaned and crushed before being heated at high temperature, which causes a series of changes inside the oils: destroying oil cells, promoting protein denaturation, reducing oil viscosity and so on, so as to be suitable for hot oil press machine to extract oil and improve oil extraction rate. Although the original flavor of cold pressed oil is the choice of healthy life, most oils are not suitable for cold pressed. Take soybean, high erucic acid rapeseed, cottonseed, peanut and sesame for example, the beany smell of soybean oil, spicy taste of high erucic acid rapeseed oil, gossypol toxin in cottonseed oil and aflatoxin in deteriorated oils must be refined before they can be removed. The aroma of sesame oil and aromatic peanut oil can only be obtained by hot pressing. So cold pressing is healthy and hot pressing is delicious.
Cold pressing, as its name implies, is to press the oil directly into the cold press oil expeller
without heating the oil after screening. Such a pressing method is very difficult to press clean at one time, and the oil content of the oil cake is also there. Some need this type of oil cake, less oil content, but not completely oil-free. The advantage of cold pressing is that the color is lighter. When the oil is pressed, it will not frother, and it will not appear the phenomenon of silt pot. The color is better. The disadvantage is that the smell of oil is not very fragrant, and it takes more than two times to press clean.
Hot pressing is just the opposite of cold pressing. Oil is pressed only after heating. This way of pressing is one-time and can be pressed clean. The resulting oil cake has almost no oil content. So oil cake is completely deoiled cake, which can be used in making oil-free material cake. The advantage of hot pressing is that the crushed oil is very fragrant and mellow. The oil added by hot pressing is more oily than that by cold pressing. However, due to the phenomenon of silt pot in hot pressing all the time, we need to pay attention to this when pressing by hot oil press machine. When pressing, we should not be too anxious to feed, and cut the material according to the amount of crushed oil.