Firstly, the production process is different. The cold pressed oil is pressed at room temperature, the oil temperature is low, and the acid value is also relatively low. So there is no need to refine. We would get the oil products after precipitation and filtration. While in the hotly pressed oil production process, we heat the seeds up or add chemicals to help. Some seeds like sesame seeds need to be hot pressed because they hold such little oil. Also, the raw oil is relatively dark after high-temperature treatment, the acid value will rise, so the crude can be edible only after refining.
Secondly, the oil quality is distinctive. The cold pressed oil is with natural properties. It could avoid the adverse effects caused by traditional high temperature, retain the physiologically active substance and its original taste and flavor. It is a pretty good choice for a healthy life. Hot pressed oil is with pure taste. The oil plants are pressed after fried. It smells good especially for oily plants like sesame seeds. while there are a series of changes in the oil plants. The process will destruct the plant cells, denature the protein, reduce oil viscosity, and improve the yield efficiency. What’s more, the bioactive substances in the oil such as vitamin E, sterol, Carotenoid will endure a massive loss.
Thirdly, something about the cooking process. Cold pressed oil in deep-fried will not foam or silt. The condition is different when it comes to hot pressed oil.
Fourthly, they apply to the diverse raw material. The cold pressed oil is always squeezed below 60℃. Some oilseeds such as camellia, coconut, flaxseed, hemp, and olive seeds are suitable for that. However, the mashed material is then heated to 100-120℃ in a so-called cooker in the hot oil processing. Let’s take soybean, high erucic acid rapeseed, cottonseed, peanut and sesame for instance. The produced oil must be processed through oil refining process, Because there is a beany flavor in soybean oil, spicy flavor in high erucic acid rapeseed oil, toxin-cottorrpherol in rapeseed oil and aflatoxin in degenerative oilseeds. All above must be refined. Also, the flavor of sesame oil and fragrant peanut can be got only after hot processing.
The last but not the lest, the oil yield. The oil yield achievable through cold pressing is typically between 34,5-35,9% of the total weight of the input material (in case of 42% oil content), while the hot one is normally between 35.7%-37.8%.
Considering all the above, when choosing between cold and hot pressing technologies, one must always consider what you need clarification.