Refined Oil Quality

Some invaluable isolated actions were taken from time to time in the last twenty to twenty five years that prevented air quality from declining at an even faster rate. For example, energy demand was met (electricity and refined oil products) by expanding capacity of plants located outside of the MCMA a metro was built the vehicular traffic system was reordered and new hydrotreating, reforming and catalytic cracking units reduced lead and sulfur in refined products. 

Considerable data have been published and additional unpublished confirmatory data have been collected which indicate that for a given degree of refinement, measured by increased viscosity index or decreased viscosity gravity constant, the quality of refined oils produced by all popular solvent refining processes is so nearly equivalent that there is no clear-cut generalization possible which would favor one process over another. From the point of view of economy, two other considerations are important—namely, selectivity and... 

With non-refined oils it is sometimes possible to extract intact DNA from them, apply PCR amplification, and then examine the product by gel electrophoresis. If any GM component is present, this would then be detectable. However, oils that are sold non-refined are not generally the oils that are being produced in GM forms. It is possible that in future there may GM olive, hazelnut, walnut or other non-refined oils, and it is likely that these could be tested in this way. One other oil product that can be tested is lecithin. Where there has been severe heat damage, it is not always possible to extract suitable DNA from the product, but, with samples that have been only mildly treated, it is often possible to achieve accurate results by PCR. Each case has to be evaluated separately depending on the condition of the sample, and the quality of the methods used. 

A practically odourless clear oil with a faint yellow tinge. Inexpensive, thin and non-oily it is especially suitable for blending with other carriers. Extracted from the seeds, which have a long tradition in culinary applications. The oil is available in a range of qualities and is also a favourite for cooking but this is the highly refined oil, which is not usually recommended for aromatherapy. External use is believed to be beneficial for skin problems such as ulcers, bruises, acne and seborrhoea. Fatty acid composition linoleic acid (up to 74%), oleic acid (up to 15%), palmitic acid (up to 6.4%), stearic acid (4.2%), linolenic acid (0.2%) and palmitoleic acid (0.1%). It is also high in vitamins A, B-com-plex, D and E, with minerals calcium, potassium, iron, zinc and phosphorus. Considered to be a safe oil with no reported contraindications. 

A typical chemical composition of crude, refined, and deodorized canola oils is presented in Table 12. The deodorized oil data represents the oil quality used as a food ingredient. 

In the most recent development, acid and aqueous sodium hydroxide, rather than acid and water are being used, especially with lower quality oils (acid-caustic degumming). This represents an intermediate between acid-water degumming and alkali refining. It obviates the need for cooling, similar to the practice in alkali refining. Phosphoric acid rather than an organic acid is preferred in this case. Phosphatides as well as some of the other impurities are removed, and if sufficient, alkali is applied to saponify the free fatty acids, fully refined oil is obtained. 

Typical properties of alkah-refined, bleached canola oil and of acid-water-degummed, acid pretreated, bleached canola oil ready for hydrogenation or steam refining/deodorization are given in Table 16. With the exception of the concentration of free fatty acids, the two process routes produce the same bleached oil quality. 

Phospholipids. These components are better known to oil processors as phospha-tides and are frequently referred to, together with small quantities of carbohydrates and resins, as gums that have adverse effects on product quality and refined oil yield. Phosphatides are emulsifiers, and so hinder the separation of oil and water phases in the caustic-refining process. The phosphatides are broadly separated into hydratable and nonhydratable types. As the name implies, hydratable phosphatides can be removed by treatment with water, and the nonhydratable compounds, which are salts or coordination compounds of calcium and magnesium primarily... 

Hydrolysis of phosphatides and pigments in the crude oil miscella requires an acid pretreatment, which usually varies between 100 ppm and 500 ppm by weight of the oil, depending on the quality of the crude oil. An acid such as phosphoric or glacial acetic has been found effective in improving oil quality and reducing refining losses. Phosphoric acid is used more commonly because of its less corrosive properties and its availability. The acid is mixed with the miscella in a static mixer to provide an intimately dispersed acid phase that immediately reacts with the crude miscella. 

If proper precautions are not taken and the olives are collected in large batches and held in piles several meters high, the fruit may be damaged. The enzymes released will cause hydrolytic and oxidative transformations resulting in off-flavors that affect the quality of the oil. Even with low acidity, such oils will have an unpleasant taste not acceptable for virgin oil and will have to be refined. Because of the difference in price between virgin and refined oils, economic losses to the farmer can be high. 

The overall oil quality change during refining of soybean oil was examined by Jung et al. (178), and their results are shown in Table 13. A study of oxidative... 

Fresh Oil. Fresh frying oil is obtained by refining palm oil or seed oils. It would be appropriate to briefly discuss the vegetable oil refining process for the readers to understand how various processing steps impact the quality of freshly refined oil. Vegetable oils are refined principally by ... 

Repeated refining of the crude oil because of poor crude oil quality... 

Seeds must be dried before storage. Failure to do so can increase enzyme activity in the seeds and damage the oil inside. Moisture content, the drying process, and the storage condition of the seeds impact the quality of the crude oil obtained from the seeds. In extreme cases, it becomes very difficult to obtain refined oil with high stability and good color from poor quality or poorly handled seeds. 

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