Edible oil refinery industries are facing the biggest challenges and opportunities in decades. The edible oil refinery suppliers are going through a difficult period in which they have to meet the growing oil demand and also face the increased regulatory pressure. To stay competitive, refinery suppliers should bring more expediency in the refining of edible oil while achieving production goals.
Maintaining Quality is Important
Edible oil refinery suppliers have to maintain stringent quality requirements to ensure customer never complain of poor quality oil products. Maintaining quality is important for oil processing industry because any negligence towards quality can lead to large scale health hazards that can tarnish the reputation of oil processing companies.
A safer way to bring expediency in refining process is following standard refining process that is distributed in 5 stages. Let’s look at the refining process in detail.
It is the first stage of the refining process that works to remove impurities (especially phosphatides which are called gums) of the cooking oil. Phosphatides are present in edible oil extracted from rapeseed, soyabean, and sunflower seed oil. These impurities need to be removed at early stages of refining due to their emulsifying properties. If the degumming process is ignored, the risk of decomposing and darkening of the oil increases due to thermal instability.
Also known as Alkali refining, the neutralization process refers to the removal of fatty acids. In the neutralization process, the free fatty acids are removed by using alkali like caustic soda. When caustic soda reacts with free fatty acids in a tank, it leads to the formation of soap stock that settles at the bottom of the tank which is then removed.
The bleaching process is preceded by degumming and neutralization process. It works to remove contaminants that adversely impact the appearance and performance of triacylglycerol in edible oil. The bleaching process involves mixing of edible oil with clay adsorbent to remove color. Besides removing some of the colors, the bleaching process also reduces the contents of residual soaps and gums, chlorophyll, oxidation products, and trace metals.
Though the bleaching process looks simple that involves mixing of adsorbent followed by filtration, the physical and chemical reactions that take place in the bleaching process are quite complex. The effectiveness of the bleaching process depends on various factors like temperature, moisture, vacuum, and contact time. Other important factors are the type of equipment used and the amount and the characteristics of the adsorbent.
In the deodorization process, the edible oil goes through high-temperature, high-vacuum steam distillation process to remove odoriferous and volatile materials. The deodorization process plays an important role in removing off-flavors from edible oil. It also removes free fatty acids (non-sterified) that are not removed by early stages of the refining process.
Over the years, the deodorization process has greatly improved and has made oil refining process more efficient leading to lower operating cost, high refined oil yield and better valorization of side streams.
Also known as dewaxing of edible oils, the winterization process refers to a thermo-mechanical process in which solid particles in the edible oil are crystallized under controlled climatic conditions. The next refining stage is a mechanical separation of the crystals. The dewaxing process is recommended for edible oils that show turbid characteristics below 5 degree Celsius. Some of the edible oils that are put through the winterization process are cotton and sunflower seed oil.
In the winterization process, the edible oil is mixed with a crystallizing agent and then run through a static mixer. The mixture is then cooled in a recuperative exchanger where crystallization takes place. The next step is filtration.
By following above refining process, oil processing companies can control the quality of the oil products throughout the refining process and get a clear view of the end product right from start.