The Digestion , Absorption and Utilization of Refined Palm Oil , Palm Olein and Palm

A nutritional evaluation of refined, bleached and deodorised (RBD) palm oil and its fractionation products, RBD palm olein and RBD palm stearin in terms of their digestibility, rate of absorption and food efficiency in rats, shows that RBD palm olein is a better oil by these criteria than RBD palm stearin and the unfractionated RBD palm oil. Nevertheless, the nutritional indices reported for RBD palm oil and RBD palm stearin are well within the range reported for most cooking oils and fats. The digestibility and food efficiency ofRBD palm olein are comparable to that of soybean oil, being 97% and 98% respectively of the values found for the latter oil, although the absorption rate ofRED palm olein is 10% less than that obtained for soybean oil. INTRODUCTION Edible fats and oils are generally 93-98% digestible (Langworthy, 1923; Crockett and Deuel. 1947). The digestibility of palm oil, which was reported to be 97% (Calloway et al., 1956), falls within this range. On the other hand, fats with melting points above 50 C (Crockett and Deuel, 1947), those that contain higher amounts of stearic acid (Mattil and Higgins, 1945) or triglycerides that contain only saturated. long-chain fatty acids (Mattson, 1959) are less readily digested or absorbed. Subsequent studies showed that pancreatic lipase specifically hydrolyse the fatty acids esteri*The information reported in this paper is contained in the Ph. D thesis of T.K.W. Ng. University of Malaya, 1987. 1Department ofBiochemistry, University ofMalaya, 59200 Kuala Lumpur. 2Palm Oil Research Institute ofMalaysia, Bandar Baru Bangi 43000 Ka;ang. T.K.W. NG, H.T. KHOR AND Y.H. CHONG fied in the 1and 3-positions of a triglyceride (Mattson et al., 1952) and that a high content of palmitic acid esterified at the 2-position of a fat favours its absorption (Tomarelli et al.• 1968; Filer et al.. 1969). Generally, only a small percentage of the total palmitic acid of vegetable fats and oils is present in the 2-position of the triglyceride molecule; saturated fatty acids having a chain length of more than 18 carbons are found predominantly in the I-and 3-positions (Bracco and Bauer, 1978). In an earlier report (Ng, Chong and Khor, 1987), it was shown that the energy availability of RBD palm oil and RBD palm olein are comparable to that of soybean oil. Other than this communication and the very few early fat digestion and absorption studies which included unfractionated refmed palm oil reported in the literature, there is practically no information available on common nutritional criteria such as digestibility, absorbability and food efficiency for Malaysian RBD palm olein and RBD palm stearin, although these relatively new processed palm oil fractions are now widely used in cooking and food processing, Thus, there is a fundamental need to establish these nutritional indices mentioned for Malaysian RBD palm oil, RBD palm olein and RBD palm stearin. The information obtained should be of value to local nutritionists and food technologists involved with product development or marketing in the palm oil industry. MATERIALS AND METHODS