The raw material used in this study were the liquid fraction of crude palm oil (CPO) obtained from a palm oil industry in Indonesia, and some coating materials such as arabic gum, gelatin, maltodextrin, carboxyl methyl cellulose (CMC), and SiO₂. Other materials used were phosphoric acid and chemicals for analyzing palm oil and MPO. Equipment used in this study were hotplate and magnetic stirrer (Mega-mix PMC), homogenizer (IKA Labortechnik basic RW16), centrifuge (Hermle Z 383 K), freeze dryer (Christ Alpha 2 - 4 Ldplus), high performance liquid chromatography (HPLC, Shimadzu, Japan), analytical balance, vacuum oven, polarized light microscope (Olympus C-35AD-4), and glassware.

Palm oil was processed with a minimum refinery step through degumming process to minimize loss of β-caro- tene content. Degumming is a separation process between oil from sap or slime which consists of phospholipids, proteins, residues, carbohydrates, water, and resin [14]. In this research, dry degumming process was used by adding 85% phosphoric acid solution at 80˚C. Results in Table 1 showed that the degummed palm oil did not contain ash and protein. Impurities contained in crude palm oil could be effectively separated through degumming process. This result was supported by the peroxide value which also decreased after degumming process. Metals are catalyst in the oil oxidation process to form peroxide [2]. Phosphoric acid added during degumming process can initiate the formation of clots that facilitate the deposition of dirt, lowered peroxide, and improve color stability of oil [14]. Free fatty acid content and water content that were increase during degumming process possibly due to hydrolysis reaction, were still meet the quality requirements from National Standards of Indonesia (SNI 01-0016-1998). Degumming process also decreased β-carotene content of palm oil from 366.18 to 290.55 μg/g. Degradation of β-carotene are generally caused by light, oxygen, metals, and high temperature. Degumming process was carried out at 80˚C that could cause damage of β-carotene.

MPO were made by using three methods, namely coacervation, thin-layer drying, and absorption of SiO₂ techniques. The appearance of MPO can be seen in Figure 1. The MPO’s were shaped as granules or powder with yellowish color.

Coacervation technique has advantages due to the easiness of obtaining the materials used and for its low temperature used, although the procedure was time consuming. The exposure of β-carotene in palm oil to the environment was more intensive, so that the retention of β-carotene can be low. Another drawback for this technique was the use of formaldehyde as a cross-linking agent. Formaldehyde is banned from used in food because it’s carcinogenicity.

Thin layer drying technique has some advantages such as the coating materials and equipment can be easily obtained. However, the drying process that was carried out at temperature of 60˚C for 5 hours potentially could damage β-carotene content. Another drawback was the capacity of vacuum drier that was limited so it can’t be used to produce large quantity of MPO.

SiO₂ absorption technique was very easy to apply and does not require long time and specific equipment. β- carotene was more protected from the damaged because this method did not involve pH adjustment and high temperature process. However, SiO₂ is not a compound commonly used so that it is difficult to be obtained.

Chemical characteristics of MPO are presented in Table 2. Three types of MPO had water content less than 3%, which was also affected by the coating material used. MPO is expected to have a low moisture content to avoid the hydrolysis reaction that can make the oil and β-carotene damaged.

Total oil content was affected by the amount of palm oil added, that was determined by encapsulated oil content. β-carotene content in MPO was lower than that of degummed palm oil. MPO made by thin-layer drying has the highest content β-carotene as much as 200.16 μg/g with the retention of 68.89%. β-carotene is easily degraded by the process of oxidation, heat, and light. MPO made by coacervation technique contain of 42.83

The same letters after the numbers in the same row indicates no significant difference (p > 0.05).

The same letters after the numbers in the same row indicates no significant difference (p > 0.05).

μg/g β-carotene with 14.74% retention. The loss of β-carotene in this method may occur during pH adjustment and during drying process of MPO that still can be exposed to light. Meanwhile, the content of β-carotene in MPO made by SiO₂ absorption was very low, contain 1.75 μg/g that equal to 0.60% retention. This was caused by the property of SiO₂ that was very stable to chemical reactions that could not release β-carotene during analysis.

The highest yield was obtained from SiO₂ absorption technique, because it was made only by mixing SiO₂ and palm oil without any centrifugation and drying process. The highest microencapsulation efficiency also was obtained by SiO₂ absorption technique, while the coacervation technique only had 7.37%. The percentage of encapsulated oil during microencapsulation process was approximately about 50% for thin layer drying and SiO₂ absorption technique except for coacervation technique with only 32.03%. Several factors that affect the efficiency of microencapsulation are the concentration of the polymer coating, the ratio of DP/CP, and the speed of removal of the solvent [15]. In coacervation technique, the concentration of coating material used is very small, whereas in the SiO₂ absorption method, the concentration of coating material used is proportional to the concentration of oil added. MPO produced by thin-layer drying has a better efficiency than the product of coacervation technique because its ratio of DP/CP and its drying speed was higher.

Physical properties of MPO that was studied were the water absorption and solubility in water (Table 2). MPO produced by coacervation technique had the highest water absorption. This was caused by the porous structure of MPO after freeze drying process that easily absorbing water. MPO produced by thin layer drying has the highest solubility. This occurs because the coating materials used are CMC, gelatin, and maltodextrin that have good solubility in water.