Refining Vegetable Oils: Chemical and Physical Refining

This review presents recent technologies involved in vegetable oil refining as well as quality attributes of crude oils obtained by mechanical and solvent extraction. Usually, apart from virgin oils, crude oils cannot be consumed directly or incorporated into various food applications without technological treatments (refining). Indeed, crude oils like soybean, rapeseed, palm, corn, and sunflower oils must be purified or refined before consumption. The objective of such treatments (chemical and physical refining) is to get a better quality, a more acceptable aspect (limpidity), a lighter odor and color, longer stability, and good safety through the elimination of pollutants while minimizing oil loss during processing. However, the problem is that refining removes some essential nutrients and often generates other undesirable compounds such as 3-MCPD-esters and trans-fatty acids. These compounds directly influence the safety level of refined oil. Advantages and drawbacks of both chemical and physical refining were discussed in the light of recent literature. Physical refining has several advantages over chemical one.

Enzymatic Methods for the Manipulation and Valorization of Soapstock from Vegetable Oil Refining Processes

The review will discuss the methods that have been optimized so far for the enzymatic hydrolysis of soapstock into enriched mixtures of free fatty acids, in order to offer a sustainable alternative to the procedure which is currently employed at the industrial level for converting soapstock into the by-product known as acid oil (or olein, i.e., free fatty acids removed from raw vegetable oil, dissolved in residual triglycerides). The further biocatalyzed manipulation of soapstock or of the corresponding acid oil for the production of biodiesel and fine chemicals (surfactants, plasticizers, and additives) will be described, with specific attention given to processes performed in continuous flow mode. The valorization of soapstock as carbon source in industrial lipase production will be also considered.

Evaluation of reusability of bleaching earth in vegetable oil refining

Purpose Unrefined vegetable oils contain triglycerides and free fatty acids as the main ingredient, but besides, they contain waxes, phospholipids, tocopherols, β-carotene, chlorophyll and other trace amounts depending on the type of oil. Most undesirable substances such as residues, free fatty acids and phospholipids are separated in the neutralization process of the oil refining. As a pigment, β carotene is separated by the bleaching earth (BE) in the bleaching process. The BE is disposed of as waste after the bleaching process. In this study, waste BE, which is allocated for disposal, has become reusable. Design/methodology/approach For this purpose, the oil is separated from the BE by solvent extraction under room conditions. AOCS Ba 3-38, TS EN ISO 734, ISO 15305 and TS 324 standard methods were used. Findings As a result of the analysis, it was found that 1% of oil remained in the recovered BE. The recovered BE containing 1% oil was carbonized at 550oC for 1 and 2 h. The BE obtained after this process was used in the bleaching process at a rate of 1%. Reuse attempts were repeated seven times, colour-opening capacities were measured and BET analyses were performed to establish a relationship between surface area-discolouration capacity and reusability. Originality/value This study demonstrates that recovery of waste BE can be performed and if this reusability considers in the industrial scale, it will save on oil refining costs and reduce waste.