Crystallization of Oil and Fat Products

When it comes to predicting the point of crystallization, it gets more complicated. Crystallization of oils or fats or of FAME is a thermodynamic process. FAME crystallization by itself is probably much simpler than the complex crystallization of oils and fats as seen in food products from chocolate to margarine. Basic research on FAME crystallization is in progress, but currently not readily available to put in a simple and useful mathematical model sufficient to describe the CP, PP, or CFPP. 

Quality control systems usually used for judging the quality of oils and fats or oil blends used in margarine production could evaluate color, color stabihty, flavor, flavor stabihty, free fatty acid, peroxide value, active oxygen method (AOM) stabihty, iodine value, shp melting point, fatty acid composition, refractive index, crystallization rate, and sohd fat/temperature relationship (solid fat index) (5, 91, 112, 113). 

Metin S., Haitel R.W. Crystallization of fats and oils. In Bailey s Industrial Oil and Fat Products, 6th edn, (F. Shahidi, ed.), John Wiley Sons, Ltd, Chichester, (2005). 

The simultaneous reflection of light from many parallel layers produces the characteristic pearly luster, the hril-liance of which depends on the uniformity and parallelism of the crystals. Natural pearlescent pigments are composed primarily of guanine crystals derived from fish scales. They are expensive but nontoxic. The synthetic pearlescents are based on crystallized lead or bismuth compounds or platelets of mica coated with a dye or pigment. (Bailey s industrial oil and fat products. Shahidi F, Bailey AE (eds). Wiley, New York, 2005)... 

Many edible oil products contain various combinations of p and p tending components. The ratio of p-p crystals helps to determine the dominant crystal habit, but the higher melting triglyceride portions of a solidified fat product usually force the fat to assume that crystal form. The crystal form of the solidified fat product has a major influence upon the textural properties. Fats exhibiting a stable p form... 

Oils and fats go through a series of increasingly organized crystal phases upon cooling. This multiple form of crystallization (polymorphism) is an important characteristic of fats and oils because it greatly influences the textural and functional properties of fats and fat-based products. 

The most important functionality of a solidified oil and fat is its plasticity, consistency or spreadability . A shortening or margarine product may appear to be in a homogeneous solid state, but it consists of discrete solid (crystal... 

CHEMICAL PROPERTIES noncombustible solid gradually absorbs carbon dioxide upon exposure to air reacts with hydrochloric acid to produce zinc chloride reacts with sulfuric acid to produce zinc sulfate, and it reacts with carbon monoxide or hydrogen to produce elemental zinc reacts lowly with fatty acids in oils and fats to produce lumpy masses of zinc oleate, stearate, etc. forms cement-like products when mixed with a strong solution of zinc chloride or with phosphoric acid, owing to the formation of oxy-salts hydrogen peroxide is produced when ointments containing zinc oxide and water are melted and exposed to UV light FP (NA) LFL/UFL (NA) AT (NA) HC (NA) HF (-350.5 kJ/mol crystal at 25°C) pH (6.95 American process zinc oxide, 7.37 French process zinc oxide). 

Products such as margarine and butter contain, apart from oil and fat, about 20% water. This water is present as finely dispersed droplets (a few micrometers in diameter) covered by a shell of fat crystals. Typical margarine is formed by a continuous fat matrix (Figure 2.15) that appears to be an interconnected network structure composed of single crystals and sheet-like crystal aggregates. The shells of the water droplets, showing the crystalline nature of the interface, are inserted in this fat network. 

Crystal polymorph plays a key role in final product consistency and acceptability. Smaller crystals lead to firmer fat products, whereas larger fats give a sense of sandiness in the mouth. Incorporation of large amounts of liquid oil increases the tendency of the desirable P polymorphic form to convert to the p form (deMan et al., 1995). In the production of butterfat-canola oil spreads, preserving the P form would be essential in order to avoid a sandy mouthfeel. 

D. Now the ether will be a deep reddish yellow. Distill off the ether...quack...and take the temp up to 170 C to drive off any other volatiles. Should recover 90%+ of the original weight of oil. Now add 500 ml of saturated bisulfite and stir for 1.5 hours...Quack Vacuum Filter, the duck fat crystals Wash with water and ether, yield dull fine ppt in the filter cake...stable bisulfite addition product...can be stored forever...QuackU Yield -50 to 80% depending on a ducks technique ... 

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