Most of the oil presses sold by AGICO are available in hot pressing configurations as well. The main difference between cold and hot pressing does not affect the pressing equipment to a great extent, rather it has implications for the preparation of the input material. Due to the different preparation the input material has different characteristics in case of the two pressing methods, which require different press worm configurations. The worm configuration and some other settings are basically the differences between press units for cold and hot pressing.
1. What are the main differences between cold and hot pressing technologies?
The cold pressing of oily seeds does not require any pre conditioning of the input material. The only requirement is that the input seed is 98% clean and free of metal and stone particles. 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). In case of hot pressing, the 98% clean, stone and metal free input material is also required, and the material is conditioned for pressing in two more steps. First the seeds go through a masher which breaks up the seeds, and the mashed material is then heated to 100-120 degrees (Celsius) in a so-called cooker. From the cooker the hot material is loaded directly into the press. The oil yield in case of hot pressing technologies is normally between 35,7-37,8% of the total weight of the input material (in case of 42% oil content).
2. What are the advantages of cold pressing?
The oil produced with cold pressing technologies is of very high quality. In our experience, cold pressed rapeseed oil is suitable for biodiesel production (etherification) without any further processing. This means that the critical quality measure for etherification, the phosphorus content, remains desirably low below 35 ppm. As opposed to this, vegetable oil produced with hot pressing technology typically has a phosphorus content of 200-500 ppm; therefore, if the desired use of the oil is biodiesel production additional investment in degumming technology (to reduce the phosphorus content) is inevitable. In addition to considerations regarding the final product, we must also mention that cold pressing technologies are typically significantly simpler and their operation requires considerably less energy and equipment (no need for steam furnace, masher, conditioner etc.). From a practical point of view this means that investments in cold pressing technologies characteristically require less capital to realize than hot pressing technologies, while their operation and maintenance is also less costly. When choosing between cold and hot pressing technologies, one must always consider the intended use of the produced vegetable oil, as well as other factors influencing return (ex.: existing infrastructure). When choosing between cold and hot pressing technologies, one must always consider the intended use of the produced vegetable oil, as well as other factors influencing return (ex.: existing infrastructure).
3. What are the advantages of hot pressing?
The most significant benefit of cold pressing technologies is that the oil yield is higher than in case of cold pressing. However, the quality of the oil produced with such technology renders the oil unsuitable for biodiesel production without further processing, i.e. degumming (also see question no. 2. ). When choosing between cold and hot pressing technologies, one must always consider the intended use of the produced vegetable oil, as well as other factors influencing return (ex.: existing infrastructure).
