( 27 ) Food Preservation Science VOL. 23 NO. 4 1997 (Research Date 207 Utilization, Storage and Evaluation of Coconut Oil from Nata De Coco Scrapings DIZON,E. I*., MENDOZA,M. G.* and IINO H.** * Institute of Food Science and Technology, University ofthe Philippines Los Banos, College, Laguna 4031, Philippines; ** Showa Women's University, Taishido 1-7, Setagaya-ku, Tokyo 154, Japan. Crude oil from nata de coco scrapings was extracted using the modified Cruz-Bernardo process and oil refining was done by alkaline method. Chemical properties of the refined oil revealed that the differences in the sources of coconut, extraction method and refinement process do not affect the properties of oil as evidenced by the values obtained which fall within the acceptable established constants for coconut oil from fresh coconuts. Storage stability studies of the extracted crude oil at ambient room temperature for six-and-a-half months showed that oil stored in colored containers and treated with .035% a-tocopherol was significantly less prone to hydrolytic rancidity as compared with the untreated samples. However, crude oil from nata de coco cream has significantly higher free fatty acid values when compared with oil samples from fresh coconuts. Utilization of refined oil from nata de coco cream for deep-frying of plain prawn crackers showed in no significant difference the over-all quality of the samples deep-fried in two commercial brands of coconut oil. Nata de coco, a sticky of gelatinous substance, of coconut and nata de coco was one of the main is formed by a bacterium called Acetobacter aceti products of this effort. subsp. xylinum. The bacterium acts on the medium Nata de coco has gained in popularity in both consisting of coconut milk, glacial acetic acid, domestic and international markets, specifically in water and sugar to form a smooth, transparent or Japan, with its peak observed in 1993 to 1994. The opaque film that floats on the surface of the demand for nata de coco in foreign markets substrate. The medium contains the nutrients increased tremendously when it was repored that which stimulates the growth of the nata organism. nata is preventive for colon cancer due to its high However, these nutrients are not transmitted to amount of fiber content. Figure-conscious people the nata formed. Thus nata de coco may be used nata de coco as part of their diet too because considered as a food without nutritive value. It is of its low calorie content . mainly composed of water and polysaccharides The nata de coco industry became so popular in (fiber) . the Philippines, that the large volume of waste The technology of nata making originated in products from its production became a problem. Pagsanjan, Laguna in the Philippines, a century When nata de coco is harvested, a slimy substance back. However, the main substrate was the juice which adheres to the underside of the film in extracted from pineapple peelings. In 1954, the contact with the medium is scraped off. It was Philippine Coconut Authority spread the wonders found out that these nata de coco scrapings 208 Food Preservation Science VOL. 23 NO. 4 1997 (28) consists mainly of oil by CABRERA,F. 1995 2).Thus, nata de coco scrapings considering the relatively in mass production of nata de coco, a large high production of nata de coco and the increasing volume of oil can be extracted from these waste demand for coconut oil as well. products. Instead of dumping these wastes in the Coconut oil, like any other oil, is composed of soil or directly in to bodies of water, there by carboxylic esters from a single alcohol, glycerol, causing increased acidity of the system and HOCH2CHOHCH2OH. These carboxylic esters are pollution in the environment, the oil may be known as glycerides. Coconut oil is mainly a extracted for utilization in products where oil is a triglyceride, or more appropriately called main ingredient. triacylglycerol and consists of three fatty acids Tapping the oil from the waste products of nata bound to one glycerol. de coco production will be beneficial as an Hydrolysis of 100g commercial coconut oil will additional source of income for the nata growers produce 96.7g fatty acids and 13.9 glycerol. This and to manufacturers of coco-based products. fatty acid mixture is made up of nine different Thus, the aims of this study were (a) to extract fatty acids (Table1) . and evaluate the chemical properties of crude and Because of the high degree of saturation and refined oil from residual nata de coco crem, (b) fatty acid compositions of coconut oil, it is used to compare the storage stability of oil from nata de extensively both in the food and non - food coco cream to that of oil from fresh coconut and industries. Similarly, basic oleochemicals are selected commercial brands of coconut oil, and produced from coconut oil, namely, glycerol, fatty (c) to evaluate the efficacy of refined oil from nata acids, fatty acid methyl esters, fatty alcohols and de coco cream for cooking purposes. fatty amines (PCARRD, 1993) .13) Several studies have been conducted regarding Table 2 shows that the physical and chemical nate de coco production howerer, there were no properties of crude oil from fresh coconut and nata published articles available concerning coconut oil de coco cream have no marked difference. The from nata de coco. It is sential to study the saponification and iodine values of recovered oil possibility of extracting utilizable coconut oil from from nata de coco cream were reported 2 ) Table 1. Fatty acid composition of crude coconut oil13) (29) 〔Research Date〕 Evaluation of Coconut Oil from Nata De Coco Scrapings 209 Table 2. Physical and chemical properties of coconut oil from fresh coconut and nata de coco cream.2)7) pre,-treated scrapings were placed in clean, dry plastic containers, covered with aluminum foil and frozen at ordinary freezer temperature for 48 hours. The frozen scrapings were thawed and centrifuged at 45,000 rpm for 10-15 minutes. The liquid portion was discarded and the emulsion that remained in the centrifuged tube was transferred to a pan, heated and the oil that separates from the emulsion was filtered and weighed. The percent oil recovery was calculated as follows Amount of oil recovered/ %Oil recovery= •~ 100 Figure 1. Nata de coco scrapings Amount of scrapings Preparation of Crude Oil from Matured, Fresh (CABRERA,1995) to fall within the range of values Coconuts set for coconut oil from fresh coconut. This Matured, fresh coconuts were cracked open and indicated that the oil recovered from nata de coco the meat was machine-grated. The coconut milk cream has undergone no substantial changes even was extracted by pressing the grated coconut after the nata organism has acted on the coco - manually, and filtered through a cheesecloth. The based substrate. coconut milk was placed on a pan and heated to MATERIALS AND METHODS boiling with constant stirring. When all the water had evaporated, the oil that oozed out was filtered. Preparation of Crude Oil from Residual Nata De The extracted oil was weighed and the percent Coco Cream recovery was calculated. The process flow Nata de coco scrapings (Figure 1) were obtained diagram for the extraction of crude oil from from various nata de coco growers around Los matured coconuts is given in Figure 3. Banos, Laguna, Philippines. The film adhering to Stability Studies of Oil from Nata de Coco Cream the underside portion of nata in contact with the A. Effect of antioxidant addition and packaging substrate was scraped after harvest. The scrapings material The total oil recovered from nata de coco were blended to a creamy state and neutralized cream was divided into two portions: one portion with 5N sodium hydroxide to until pH7. 0. was treated with ƒ¿-tocopherol (as antioxidant) at The oil was extracted from the neutralized a concentration of 0.035% by weight, while the scrapings using the modified Cruz - Bernardo other portion served as control. Each portion was process ( Figure 2 ) , a process suggested by further divided into two : one was stored in a clear CABRERA(1995) 2) to be the more efficient method container while the other in a container fully of extracting oil from nata de coco scrapings. The wrapped with a carbon paper to protect the 210 Food Preservation Science VOL. 23 NO. 4 1997 (30) samples from exposure to light. The containers (ANOVA) and Duncan's New Multiple Range were filled with oil up to the brim, covered with Test (DNMRT) to find out if significant rubber stopper and sealed with paraffin wax. differences exsisted among samples. Then, all tubes were stored at 28-30•Ž for six-and Refinement of Oil from Nata de Coco Cream -a-half months . The crude oil from nata de coco cream was Crude oil extracted from fresh, matured coconuts refined for further utilization. Oil refining was also served as control. done using the method developed by LOZADA, B. Use of Accelerated Test The stability of SUMALDE and KOONTZ (1993) 6) and the flow crude oil from nata de coco cream was studied diagram of the process is presented in Figure 4. using a simple accelerated (Schaal) test. The method is known to result in a bland and About 100 ml of oil from nata de coco crem was odorless edible cooking oil. One kilogram of crude oil was placed in a placed in a clean, dry bottle, covered with aluminum foil, and stored in a well-aerated drying stainless steel container. This was neutralized oven at a temperature of 60•Ž. The increase in free slowly for 20 minutes using 2% sodium hydroxide fatty acids and peroxide values were monitored solution.