The use of palm oil for plastic fats has encountered serious difficulty due to its crystallization properties, one of which is the formation of granular crystals. The granular crystals cause sandy taste and inhomogeneity of fat crystal morphology of end products. In the present study, we analyzed the formation process of these granular crystals. Chemical and physical analyses for triacylglycerol (TAG) compositions, polymorphism and melting points of the granular crystals led to the conclusion that the granular crystals are of the most stable polymorph, /31, of POP (1,3-dipalmitoyl 2-oleoyl glycerol} with triple chalulength structure. This conclusion was supported by reproducing the formation process of the granular crystals in a model fat blend consisting of POP and rapeseed oil. The following characteristics of {~t polymorph of POP contribute to the formation of granular crystals in fat blends containing palm oil: (i) ~1 reveals well-defined plate-like crystal morphology, which grows easily into the bulky granular form; (ii} the triple chainlength structure of POP has a tendency to segregate and does not form a solid solution together with other TAGs.

The bioreactor system to interesterify edible oils and fats at an ultra-micro aqueous phase of 100 ppm and less was investigated. The adsorption of lecithin, together with lipase onto a carrier, was effective for conducting the interesterifying reaction efficiently for oils and fats in micro aqueous phase.To improve the handling properties of palm oil at rather low temperature, palm oil was blended with canola or soybean oil, and then these blended oils were modified by enzymatic selective interesterification in a solvent-free, ultra-micro aqueous bioreactor system with an immobilized lipase that had 1,3-positional specificity. The effects of enzymatic interesterification were confirmed by triglyceride determination, by solid fat content profiles and by cloud point profiles, which were also compared to products of chemical interesterification. The improvement in the fluidity of blended oils with canola oil by the enzymatic reaction was bigger than with soybean oil, and chemical interesterification had no effects on the fluidity of blended oils.

The state of dissolved water in triglycerides (TG) such as tristearin, triolein, trilinolein, and trilinolenin, was analyzed by Fourier transform infrared and near infrared spectroscopy at 20•Ž, and compared with that of water.

Enzymatic modification of fats and oils using lipases has recently come into limelight, giving rise to a breakthrough in modification technology.This paper describes the latest development and future trend of this new technology with respect to the enzyme lipases, lipase reactions, and bioreactor systems. Particular attention is paid to the utilization of this technology in industrial production of functional fats and oils.A new topic of the reasearch work of an enzymatic reaction of conversion from diglycerides to triglycerides in crude palm olein is presented in detail.