Philippine Journal of Science 148 (4): 587-595, December 2019 ISSN 0031 - 7683 Date Received: 24 April 2019 Physicochemical Characterization of Used Coconut Oil from Vacuum Frying of Jackfruit (Artocarpus heterophyllus Lam) Pulp EVIARC Sweet Variety as Affected by Frying Cycle Jason D. Braga1, Roberta D. Lauzon2, and Lorina A. Galvez2* 1Institute of Food Science and Technology College of Agriculture, Food, Environment, and Natural Resources Cavite State University, Indang, Cavite, Philippines 2Department of Food Science and Technology College of Agriculture and Food Science, Visayas State University Baybay City, Leyte, Philippines This study was conducted to determine the quality of coconut oil (CO) used in a 2-h jackfruit pulp vacuum frying for 20 frying cycles. The % free fatty acid (FFA), acid value (AV), peroxide value (PV), moisture content (MC), and color of the CO used in vacuum frying was determined for unheated oil and oil after the 1st, 5th, 10th, 15th, and 20th cycle of frying. The FFA (0.273–0.554%), AV (0.543–1.102 NaOH/kg oil), PV (4.983–45.739 meq oxygen/kg), and MC (1.016–1.079%) showed significant increase (p < 0.05) in the oil as the number of frying cycle increased that dictated the quality of the used CO. Hunter L and b showed significant (p < 0.05) effect on oil as the number of frying cycle increases, while Hunter a indicated insignificant effect. Based on the standard set by the Codex Alimentarius Commission (CAC) for refined CO (10 meq O2/kg oil), the oil quality is still safe after the third frying cycle, which conforms with the set standards for PV and AV. The pairing of these two tests is a good measure of oil quality assessment. Keywords: coconut oil, moisture content, physicochemical quality, recycling of oil INTRODUCTION which consist of three fatty acids and one molecule of glycerol. The minor components of vegetable oil are Vegetable oil (crude, refined, bleached, and deodorized) FFAs, fat-soluble vitamins, pigments, phospholipids, is one of the main dietary components in the day-to-life waxes, sterols, and fatty alcohols (Foster et al. 2009). food consumption and is used in nearly all types of food Vegetable oils contain different kinds of fatty acids and their preparations – including frying, baking, sautéing, dressing, compositions are widely varied; however, one type of fatty marinating, and extrusion cooking. They are generally acid is generally predominant over the other fatty acids. obtained from oilseeds (i.e., mustard, sunflower, cottonseed, The physical and chemical characteristics of vegetable oils corn, and coconut); food legumes (i.e., soybean, peanut); are influenced by the quantity of fatty acid and the place, nuts (i.e., almond); or the soft substances of fruits (i.e., where it is positioned on the glycerol moiety (AOCS 2006). olives). They are primarily composed of triacylglycerols, Although conventionally named as oil, CO is actually *Corresponding Author: [email protected] a fat as it is majorly composed of saturated fatty acids 587 Philippine Journal of Science Braga et al.: Physico-chemical Characterization Vol. 148 No. 4, December 2019 of Used Coconut Oil (92%), from which 62% corresponds to fatty acids with and preserves nutritional compounds such as vitamins carbon number between 8 and 12 (Eyres et al. 2016). and minerals (Da Silva and Moreira 2008). CO belongs to a unique group of fats named lauric oils, where lauric acid (12:0) is the major fatty acid present in However, the most popular issue in frying is the repeated its composition. Palm kernel oil and babassu oil are also heating of cooking oil and using it several times. part of this group. Some researchers believe that lauric oils Consumption of oxidized products, as a result of repeated have unique properties, once they behave very differently use of oils in frying processes, causes potential health in the metabolism compared with fats majorly composed hazards (Gotoh et al. 2007). Repeatedly heating of oil may by long-chain fatty acid (Dayrit 2014). not be common to some household cooking; nevertheless, it is more common in business establishments such as fast- A portion size of 100 g of CO contains 890 kcal and food chains, restaurants, and food companies because it can 82.5 g of saturated fat (Mansor et al. 2012). Butter, lard, help reduce production expenses and earns more profit. and palm oil present a much lower concentration of this type of fatty acid (51.2, 39, and 49 g, respectively) and Since there is little information of oil quality assessment fewer calories (717, 900, and 884 kcal, respectively) for of frying under vacuum condition; hence, this study was the same portion size (Mansor et al. 2012). In addition, conducted to determine the quality of CO used in a 2-h CO lacks essential fatty acids, which are present in other jackfruit pulp vacuum frying for 20 frying cycles. vegetable oils used in cooking such as soybean oil (7% linolenic acid and 51% linoleic acid), flaxseed oil (53% linolenic acid and 13% linoleic acid), and canola oil (9.1% linolenic acid and 18.6% linoleic acid) (Mansor MATERIALS AND METHODS et al. 2012). Also, compared with palm oil, CO is low on bioactive compounds. Crude palm oil contains a total Procurement of Raw Materials carotenoid content of 500–700 mg/l (Posada et al. 2007), Mature (120-d old) jackfruit (Artocarpus heterophyllus which is not present in virgin CO. Regarding vitamin E, Lam.) – specifically the EVIARC Sweet variety – used virgin CO contains around 38 mg/kg whereas palm oil in the production vacuum fried pulp was procured at has 600–1260 mg/kg (Mansor et al. 2012). Mahaplag, Leyte, Philippines. The fruit was stored in a dry area with ambient temperature (25–30 °C) for 7 d prior to Frying is a commonly used method in food preparation. processing. Refined, bleached, and deodorized (RBD) CO Nowadays, fried foods are popular from household to produced by International Pharmaceuticals Incorporated restaurants and even in goods available in the supermarket was purchased from Ormoc City, Leyte, Philippines. shelves. Deep frying of foods at high temperature creates the welcoming special flavor, golden brown color, and crispy texture – making the food appealing, good smelling, Production of Vacuum-fried Jackfruit and very palatable. It is noted that frying causes the oil The fruit was washed, brushed, and rinsed with 10 ppm to undergo hydrolysis, oxidation, and thermal reaction; sanitizing solution; cut into half; de-pulped; and de- consequently, numerous by-products such as FFAs, seeded. The pulp (4 kg) was blanched for 1 min at boiling alcohols, cyclic compounds, dimers, and polymers (Tabee temperature. The blanched sample was cooled and then et al. 2009) can be produced. stored in the freezer –18 °C overnight. RBD CO (21 L) was heated first until 120 °C in a vacuum frying system Vacuum frying offers an alternative way to improve (KVF – 5K – GH of P. Kuizon Enterprises, Philippines) the quality of fried fruit and vegetables other than by before placing 4 kg of unthawed frozen pulp in the oil atmospheric frying (Dueik and Bouchon 2011). The and then vacuum fried at 89 ˚C at 28–30 in-Hg vacuum main factors that influence fried products are the frying (Brand-Speroni) for 2 h and 10 min. The temperature was time-temperature combination of the cooking process, the maintained using the fryer’s thermostat, which controls the correct combination of which is necessary to produce a solenoid valve. After that, the vacuum fried jackfruit pulps food product with acceptable physical attributes (Andrés- were spin-dried to remove excess oil. Finally, the vacuum Bello et al. 2010). Dueik and Bouchon (2011) showed that fried pulp was band-sealed and packed in aluminum foils. vacuum frying significantly lowered the final oil content The frying protocol was continued without a cooling in comparison to atmospheric fried vegetables, and it also period for three cycles of 4 kg fruit per cycle per day for slowed the rancidity of the oil. Most of the benefits of a total of 20 cycles. Some oil was lost when it is absorbed vacuum frying from the low temperatures used and the by the product and some went to the condenser during minimal exposure to oxygen, which reduces the adverse boiling. The oil that was lost was not replenished. Samples effects on the oil quality (Shyu et al. 1998), preserves (oil) for each frying cycle were taken for analysis. the natural color and flavor (Shyu and Hwang 2001), decreases the acrylamide content (Granda et al. 2004), 588 Philippine Journal of Science Braga et al.: Physico-chemical Characterization Vol. 148 No. 4, December 2019 of Used Coconut Oil Sample Collection and Preparation of oxygen per kg. Forty (40) mL of fresh (unused) CO and used oils from vacuum frying cycles 1, 5, 10, 15, and 20 were kept in a Statistical Analysis covered amber glass bottle and stored in the refrigerator A triplicate reading in every analysis of each treatment (4 °C) to maintain the quality of the oils. Oil samples was carried out. Data was analyzed statistically through from cycles 1, 5, 10, 15, and 20 of vacuum frying were one-way ANOVA with Tukey’s Honestly Significant collected hot, right after each frying cycle, and cooled Differences post hoc test for differences between pairs of down in covered bottle for 5 min before storage. means using the commercially available software, SPSS 17 software program (SPSS Inc., Chicago, IL, USA). A MC Determination p-value of less than 0.05 (p < 0.05) indicates statistical The MC was determined using AOAC method (1990) significance. by measuring 2 g of the CO sample into an already dried and pre-weighed crucible.