Vegetable oils

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1. GENERAL DESCRIPTION:


1. General Flowsheet of vegetable oil production


Oil processing.jpg


2. Description of techniques, methods and equipment
(BAT in the Food, Drink and Milk Industries, June 2005)

After crude oil is produced, the crude oil refining process takes place to produce edible oils and fats. In principal, there are two ways to refine seed oils: by chemical or by physical refining. Deodorization is used in both cases:

(a) Chemical refining, which is the conventional method and gives high quality product, involves the sequential steps of degumming, neutralization, bleaching and deodorization. Degumming involves the addition of water to hydrate any gums present followed by centrifugal separation. In neutralization an aqueous alkali, typically caustic soda or sodium carbonate, is splashed into the oil which has been pre-heated to around 75-95°C. The alkali reacts with the free fatty acids (ffa) in the oil to form soaps, which are separated by sedimentation or centrifugation. A drying step may be incorporated after neutralization to ensure the complete removal of the added water. The neutralized oil is bleached to remove colouring matter, such as carotenoids and other minor constituents. Bleaching uses activated Fuller’s earth with treatments typically in the 90-130°C range for 10-60min. The earth is sucked into the oil under vacuum and is removed by filtration. The bleached oil is steam distilled at low pressure to remove volatile impurities including undesirable odours and flavours. This deodorization process takes place in the temperature range of 180-270°C and may last from 15min to 5 hours depending upon the nature and the quantity of the oil, and the type of equipment used. For example, if a batch deodorizer is used, it would take between 4.5 to 5 hours depending on the oil type and the quantity. However, if the same oils were processed in a semi-continuous deodorizer it would take about 15 min.


Flow diagram for the chemical refining of vegetable oils.jpg

Figure 2: Basic flow diagram for the chemical refining of vegetable oils. LITERATURE: BAT for Food, Drink and Milk Industries, June 2005


(b) Physical refining is a simpler process, in which the oil is degummed, bleaching and then deodorized. During the deodorization step, ffa, volatiles and odours are removed by steam stripping in one step without the use of chemicals. Physical refining has a higher yield and lower costs, but produces lower quality end-product comparing to chemical refining.


3. Temperature ranges and other parameters (table)
(BAT in the Food, Drink and Milk Industries, June 2005)

a) Chemical refining:


Chemical refining.jpg


4. Benchmark data
No information is available.


2. NEW TECHNOLOGIES:

a) Changes in the process: No information is available.

b) Changes in the energy distribution system: No information is available.

c) Changes in the heat supply system: No information is available.


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