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.

Pengayaan biskuit dengan fortifikasi fraksi tidak tersabunkan mengandung senyawa bioaktif multi komponen dari distilat asam lemak minyak sawit

Palm Fatty Acid Distillate (PFAD) is a by product of CPO (crude palm oil) physical refining. PFAD containing multicomponent bioactive compounds such as tocopherols, tocotrienols, phytosterols, and squalene which accumulated in unsaponifiable fraction (UF) and can be separated by saponification. Utilization of bioactive compounds can be applied on food products by fortification into biscuits. The research aimed to determine the effect of addition level of UF from PFAD on physical and organoleptics of the biscuits and also to determine chemical characteristic and bioactive compounds from the best treatment biscuit. The method used a completely randomized design with one factor, namely the level of addition of the UF from PFAD consisted of 6 treatments and was repeated four times. Data were analyzed using Analysis of Variance (ANOVA), then continued using the Duncan’s Multiple Range Test (DMRT) with significance level of 5%. The best treatment in this study was a treatment which contained 0.5% (w/w) of the UF from PFAD. The best biscuit had chemichal characteristics included those were the water content 1.81 ± 0.06%, 2.10 ± 0.06% ash content, 27.98 ± 0.54% fat content, 8.04 ± 0.13% protein content, 0.22 ± 0.02% crude fiber content, 60.07 ± 0.66% carbohydrate content, 2.66 ± 0.00002% FFA, and 7.10 ± 0.19 mek/kg total oxidation. The best biscuit contained bioactive compounds such as 147.19 ppm α–tocotrienol, 190.30 ppm δ–tocotrienol, 68.091 ppm ϒ–tocotrienol, 5,848.45 ppm β–sitosterol, 143.97 ppm stigmasterol, 621.09 ppm campesterol, and squalene content 3,284.50 ppm.

Oxidative Quality of Acid Oils and Fatty Acid Distillates Used in Animal Feeding

Acid oils (AO) and fatty acid distillates (FAD) are byproducts from chemical and physical refining of edible oils and fats, respectively. Their high energy value makes their upcycling interesting as alternatives to conventional fats in animal feeding. The objective of this study is to characterize their oxidative quality and to provide recommendations about their evaluation for animal feeding purposes. The oxidation status (peroxide value (PV), p-Anisidine value (p-AnV), % polymeric compounds (POL)), the oxidative stability (induction time by the Rancimat at 120 °C (IT)), the fatty acid composition (FA), and tocopherol and tocotrienol content of 92 AO and FAD samples from the Spanish market were analyzed. Both AO and FAD showed low PV (0.8 and 1 meq O2/kg); however, p-AnV was higher in FAD (36.4 vs. 16.4 in AO) and POL was higher in AO (2.5% vs. not detected in FAD) as a consequence of the type of refining process. The botanical origin of AO and FAD influenced FA and tocol composition, and they influenced IT. A high variability was observed for most analyzed parameters, reinforcing the need for standardizing AO and FAD to obtain reliable feed ingredients and to include primary and secondary oxidative parameters within their quality control.

Attempts of Physical Refining of Sterol-Rich Sunflower Press Oil to Obtain Minimally Processed Edible Oil

New phytosterol (PS)-enriched sunflower seeds, which are higher in campesterol and ∆7-stigmastenol, have recently been developed. Crude oils obtained from these new sunflower seeds in 2015 and 2017 were used in this study. Oils extracted only by press (PO) and with subsequent solvent extraction (SO) were characterized. Physical refining (PhR) was used to obtain edible PO by minimal processing and to keep the PS levels as high as possible. Oils obtained by chemical processing were also studied for comparative purposes. Different bleaching treatments were examined to reduce the contents of phospholipids in the PO to levels required for PhR (<10 mg kg−1). Phosphorous levels in PO from 2015 (9–12 mg kg−1) were reduced to optimal levels by bleaching with 0.1% Trisyl and 1% Tonsil 278 FF. Contrarily, treatments with Trisyl and Tonsil (278 FF or 114 FF) were not sufficient to reduce the higher levels in PO from 2017 (15–36 mg/kg−1), thereby they were subjected to chemical refining (ChR). The PhR applied to PO from 2015 did not lead to substantial changes in the composition and total content of PS. In contrast, losses of up to approximately 30% of total PS were found owing to ChR, although the oils preserved their unique PS profiles.

About solvents used in the preparation of oils for cosmetic products complying with the Cosmos standard

Solvents have a bad reputation in the cosmetics world, at least as regards the production of specialty vegetable oils used in this market. In order to do without these solvents, the cosmetics industry tends to use only mechanically produced oils. However, there is a range of seeds for which mechanical extraction is not satisfactory. This is the case with rare, expensive, and oil-poor seeds for which pressing does not give good yields, and results in high production costs. These are also hard seeds that cannot be pressed without causing the presses to become intensely hot, and this affects the quality of the oils. In recent years, our laboratory has worked on the development of extraction techniques with ethanol and the EcoXtract® solvent (2-methyloxolane) in order to provide professionals with production methods compatible with the COSMOS standard. Ethanol is not a good solvent for oils, especially in the presence of water and at low temperature. This drawback can be turned into an advantage to recover the oil (without distillation of the solvent) by cold decantation. The extraction is carried out on the hot components, and the oil is recovered by cooling the saturated miscella for the precipitation of the lipid phase. This process makes it possible to limit the energy consumption necessary for the recovery of the oil and the regeneration of the solvent. The great advantage for oils intended for the cosmetic market is that ethanol has a better solvent power for polar lipids compared to hexane and mechanical extraction. It is possible to split the lipid extract into neutral lipids and polar lipids by adjusting the precipitation temperature or by partial distillation. At the refining step, it is also possible to deacidify and remove contaminants from crude oil by liquid-liquid extraction with ethanol. We have recently obtained interesting results by reducing the phthalate concentration of walnut oils by 90%. The use of ethanol for oil neutralization is a process which generates less loss of neutral oil than the alkaline neutralization of a mixture with high acidity, and this is less harmful than physical refining during the production of 3-MCPD esters, esters of glycidol, and trans fatty acids. EcoXtract® is a solvent derived from the chemistry of pentoses in biomass. This solvent has very good oil solvation capacities and less biological toxicity than hexane. Its production has an acceptable carbon footprint and good sustainability characteristics. It is recognised by Ecocert as suitable for producing COSMOS ingredients. Compared to ethanol, its use requires fewer preparation steps (ethanol requires rigorous drying before extraction) and it requires less circulating solvent per kilo of oil extracted. The solvent removal from the meal requires less energy and allows the use of direct steam to aid in the removal of the solvent since the miscibility of water in this solvent is limited to 4.5 g/100g.