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De Smet has supplied over 190 Fractionation plants.
Fractionation
Some vegetable oils have only limited applications in food products when they are used in their native form. They are therefore often chemically or physically modified in order to change their properties.
The prominent processes are fractionation, hydrogenation and interesterification.
Today, however, quite a number of questions arise with respect to the effect of chemical modification on the nutritional quality of oils. New technologies are developed or existing processes improved in order to respond to the new quality standards. A more integrated and combined use of the different modification technologies has therefore become necessary.
Today, it seems that, of these technologies, fractionation is definitely the ideal choice, thanks to its low operating costs, zero oil loss and reversibility.
The new trends towards low trans fats and the so called «green» products will without any doubt influence the modification processes. A combination of the different technologies, with a maximum use of dry fractionation, will open up other avenues of investigation, especially in the field of tailor-made fats for well-defined applications.
Flexifrac®
  At ambient or low temperature, a number of oils or fats present themselves in the form of a mixture of a crystallised high melting point fraction and of a liquid low melting point fraction.
The purpose of our Flexifrac® fractionation process is to separate the liquid fraction called «oleins» from the crystallised fraction called «stearins». Fractionation is practised mainly on palm oil, palm kernel oil, lard, tallow, partially hydrogenated fish or soyabean oil and anhydrous milk fat.
The process comprises three steps:
- Conditioning, which consists in heating and homogenising the oil in maturators.
- Formation of crystals through selective crystallisation. The operation is conducted in several cooling steps.
- Filtration, for the separation of the oleins from the stearins.
Main Applications of Fractionation:
- salad, dressing oils (oleins)
- margarines, shortenings
- frying, cooking oils
- confectionery (cocoa butter)
- pastry, bakery products
- speciality fats
Flexifrac Main Advantages
Large cooling surface to oil volume ratio, with short oil to cooling surface distance
Swept cooling surface with minimal distance between cooling walls and agitators avoiding any dead areas.
Perfect agitation, resulting in homogeneity in mass and temperature
Consistent high heat transfer capacity and, hence, very strict control of cooling curve which is of essence for a perfect product
Fully automated process for high quality control
Consistency in plant production capacity
Constant quality of end product
Flexibility in operation and in product change-over thanks to the limited amount of product in process apparatus
Highly selective separation yields, high value added products for easy marketing
Minimal time hold-up reducing operation costs.
Perfect extrapolation of operating parameters from the De Smet laboratory pilot plant
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Statoliser®
Fractionation of Palm kernel oil (PKO) is primarly done to make part of the oil suitable as a cocoa butter replacement fat.
In order to reply to a demand from specialty fat producers for fully automated dry fractionation plants with low manual operation, the De Smet multifunctional dry fractionation process for specialty fat production has been further extended with a new Statoliser® technology(patented) which allows to obtain results similar to panning & pressing or solvent fractionation, but with a fully automated operation, requiring minimal manpower and very low operating costs.
The availibility of more detailed technical information is subject to the signature of a secrecy agreement.
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De Smet has supplied over 70 Hydrogenation plants.
Hydrogenation
The extreme versatility of our Hydrotherm® ensures the production of oils or fats with virtually any characteristics required.
Improve melting properties
Hydrogenation is an oils and fats modification process.It is mainly used on vegetable oils like soya, rape, cotton or sunflower to increase their oxidative stability and to improve their melting properties by reducing their degree of unsaturation.
As a result, these oils or fats reach a consistency that is ideal
for use as margarine or shortening components.
Stable high-quality oils
It is also possible to hydrogenate soyabean oil and fish oil and then to winterise or fractionate them for the production of very stable high-quality salad oils.
Hydrogenation is a reaction involving the use of a catalyst, most generally nickel, and is also an exothermic reaction.
For each iodine value unit drop, the oil temperature increases by 1.6 – 1.7°C. This heat is generally recovered to supply the factory low pressure steam headers.
Perfect mixing
Careful and precise hydrogenation requires that the constituents – oil or fat, gaseous hydrogen and solid catalyst – should be mixed perfectly. This is done in a closed vessel – the hydrogenator – by agitation of the catalyst – fatty material suspension in contact with hydrogen.
The purpose of agitation is to promote hydrogen absorption and to maintain a permanent flow of fatty material through the pores of the catalyst.
To do this, we use the so-called "dead-end" hydrogenator, in which hydrogen is forced into the oil and remains in it until the gas is fully consumed.
The dead-end hydrogenator is semi-continuous. It is equipped with several features to control and master reaction pressure, reaction temperature and the quantity and flow of hydrogen injected, all of which are essential to guarantee
selective hydrogenation.
The feedstock used for hydrogenation is usually caustic refined and bleached oil. With the improvement of the degumming
processes, there is a tendency to hydrogenate degummed oils. After hardening, those oils are bleached and physically refined. Oils for hydrogenation must respond to the following quality requirements.
| Free fatty acids: |
< 0.05%
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| Soaps: |
< 25 ppm |
| Phosphorus: |
< 2 ppm |
| Moisture: |
< 0.05% |
| Peroxide value: |
< 0.5 meq/kg |
| p-Anisidine value: |
< 10 |
Selectivity
Selectivity is a determining criterion in the reaction as the saturation of the double bonds must not take place at random but according to a specific pattern.
Selectivity is more than a single concept :
- Selectivity (S1) is high when multiple unsaturation in the fatty acid chains is preferentially eliminated and the formation of saturated acids reduced to a minimum.
- Triglyceride selectivity is high when the attack on the fatty acid groups in the triglycerides is at random, that is as if they react as independent molecules.
It is low when the attack of the 3 fatty acids in a triglyceride is correlated. Then S3 > s3 , where S is the stearic acid concentration.
- Specific isomerisation. In any catalytic hydrogenation, isomerisation takes place.
The number of trans double bonds formed per double bond eliminated is a measure of the degree of isomerisation.
Hydrotherm Main Advantages
Improved gas dispersion;
High flexibility with selectivity;
Low specific energy consumption;
Steam production
Fully automated plant;
Reliable controls;
No venting required as hydrogen is entirely consumed at the end of the reaction
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De Smet has supplied over 30 Interesterification plants.
Interesterification
Interesterification consists in modifying the physical properties of the oil by an interchange of fatty acids between and inside the different triglycerides, by mean of a catalyst. This is done by a catalyst operating at about 100°C and under vacuum.
The purpose of interesterification in our Interchem® process is to:
- change the overall melting profile,
- improve the compatibility of the triglycerides in the solid state,
- improve the plasticity of the resulting solid by changing the crystallisation properties,
- combine the properties of mixed oils and fats.
Interesterified oils are used mainly in:
- Coating fats,
- margarine,
- sweets,
- shortening,
- pastry,
- speciality fats.
Enzymatic interesterification (Interzym)
De Smet has also developped an enzymatic interesterification technology, called Interzym, in collaboration with the company Novozymes (Denmark).
Enzymatic interesterification is an efficient way of controlling the melting characteristics of edible oils and fats. This is done by controlling the degree of conversion/reaction. No chemicals are used in the process and no trans fats are formed as in other production methods. Until recently the technology was not widely used due to the high cost of the enzyme, but now the application using the enzyme Lipozyme® TL IM is a cost-effective alternative to both chemical interesterification and hydrogenation.
 The De Smet Interzym process is designed for the use of Lipozyme® TL IM enzymes from Novozymes.
More information about Lipozyme® TL IM can be found on http://www.novozymes.com
The main advantages of Interzym are :
- Healthy oil modification without destruction of natural minor components like vitamin E
- More natural process
- No color fixation or reversion
- Low catalyst use (0,2-0,4 kg/ton)
- Safer catalyst handling than in case of chemical interesterification
- Much lower oil loss
- No posttreatment of the interesterified oil.
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