Effect of Sweeteners and Stabilizers to Characteristics of Virgin Coconut Oil Emulsion Bonita Anjarsari 1, Nana Sutisna Achyadi 1, Ridwan Rahmat 2, Mega Teja Carlina 1 1 Program of Food Technology Masters, Graduate Faculty, Pasundan University Jl. Sumatera No. 41 Bandung West Java, Indonesia 2 Indonesia Centre for Agriculture Postharvest Research and Development Jl. Tentara Pelajar No 12, Bogor 16114 - West Java, Indonesia Email : bonnita_9@yahoo.co.id Keywords : sweetener, stabilizer, emulsion, virgin coconut oil Abstract The aim of this research was to find the effect of type of sweetener and concentrations of stabilizer on the characteristics of virgin coconut oil emulsion. The study was conducted in two stages. The second phase of research was designed using Randomized Complete Block design pattern. The first stage determined the ratio of oil and water (6:4; 7:3; 8:2) and comparison type stabilizer (Tween 80:Tween 20; Tween 80:lecithin; Tween 20:lecithin). The results showed that the ratio of oil and water (8:2) with stabilizer variation Tween 80:lecithin is the best research based on preferred sensory. The second phase determined the type of sweeteners (sucrose, glucose, honey) and the concentration of stabilizer Tween 80:lecithin (0.25%,, ). The results showed that the best treatment was obtained from the sweeteners of sucrose and stabilizers (Tween 80:lecithin) with the acid number 0.008 mg KOH/g oil, 3.90% FFA, TBA of 0.133, ph of 3.98, and viscosity of 27.67 dpas. INTRODUCTION Virgin coconut oil (VCO) is one of the refined oil which has been developed as a commercial product, because it has great benefits for human health. But the problem is that when it consumed it gives a sense of the less favored by consumers, especially the oily taste of the VCO. One way to overcome this is by processing VCO in the form of an emulsion with a taste preferred by consumers. Preparation of emulsion products with the addition of sweeteners and flavors is expected to improve the organoleptic quality, particularly the mouthfeel and flavor characteristics of the VCO. Materials that can be added are sweeteners such as sucrose, glucose and honey. In the manufacture of emulsifiers, stabilizers are needed to help shape and maintain the stability of the emulsion. The workings of stabilizer is to lower the surface tension by forming a protective layer that enveloped the droplets, so that compounds will not dissolve easily dispersed in the system. Stabilizer used is Tween 20, Tween 80 and lecithin. Tween 20 is used for solvent membrane proteins during isolation of membrane protein complexes. Due to the low UV absorbance, it is suitable for sub-protein successive detection by UV light absorption. Membrane proteins are very sensitive to peroxidase and carbonyl compounds. While protein is oxidized by peroxide, Schiff base formed during the reaction with carbonyl compounds can affect protein function. Also the salt that blocks the membrane bound protein isolation of polyoxyethylene types of contaminants may depend on the production and storage. Tween 20 has been purified to reduce unwanted peroxides, carbonyl compounds and salts. 377
Polysorbate 80 is known as non-toxic so it is safe to use in food. However, there are limitations to the use of polysorbate 80, which is as an emulsifier in shortenings or oils which is used singly, and their use should not exceed 1% of the weight of the final product. According to WHO, the ADI (Acceptable Daily Intake) of polysorbate 80 was 25 mg/kg body weight for the long term in the absence of potential toxicity. Lecithin is an integral part of cell membranes, and can be completely digested, so it can be determined to be safe for humans. However, in its use as an emulsifier either alone or in a mixture, the levels should not exceed 1% of the weight of the final product (Burdock, 1997). The purpose of this study was to determine the effect of stabilizers and sweeteners on Virgin Coconut Oil emulsion characteristics. MATERIALS AND METHODS Materials and Equipment Materials used include Virgin Coconut Oil (brand Virjint), distilled water, Tween 80, Tween 20, lecithin, skim milk (brand Greenfield), sucrose, glucose syrup, honey (brand Super Archipelago), citric acid, sodium benzoate, Butylated Hydroxy Toluene (BHT), orange flavor (brand Golden Deer) and other chemicals for proximate analysis. The tools used are scales, mixers, measuring cups, Pasteur pipette, container, spoon, spatula, funnel, spectrophotometers, and tools for proximate analysis. Research Methods This study is divided into two stages. The first stage aimed at determining the ratio of oil to water (6, 4; 7:3; 8:2) and the variation of stabilizer (Tween 80: Tween 20; Tween 80: Lecithin; Tween 20: Lecithin). The design response is used in the first stage organoleptic response (scale 1-5). Organoleptic s were conducted to determine the level of acceptance of the VCO emulsion by panelists based on the criteria of color, flavor, and aroma. The second phase study conducted to determine the types of sweeteners (sucrose, glucose, honey) and stabilizer concentrations (0.25%, 0:35%, 0:45%). Chemical analysis performed was the contents of the acid number, Free Fatty Acids and thiobarbituric acid (TBA). Physical analysis is conducted through the measurement of viscosity. Preparation of Virgin Coconut Oil Emulsion Virgin Coconut Oil (VCO) and Butylated Hydroxy Toluene (BHT) were mixed and stirred for 3 minutes to produce a stable emulsion. The mixture was added with stabilizer (Tween 80:Lecithin) with concentration of 0:25%, 0:35%, 0:45% respectively followed by the addition of skim milk to obtain stable emulsions with good taste. Homogenization is done for 3 minutes by mixing the material with sweeteners (sucrose; glucose; honey). This stage is the stage of the formation of an emulsion, wherein the oil that has been mixed with BHT was stirring until dissolved. BHT was slowly added in order to obtain good and stable emulsion. Furthermore, citric acid was added as much as 0.4%. Emulsion was then homogenized again for about 10 minutes. In the final stage, the homogenization performed for 3 minutes with addition of flavor to obtain preferred flavor and appearance of virgin coconut oil emulsion. 378
Experimental Design and Statistical Analysis The Data were statistically analyzed in Randomized Complete Block using twofactor analysis of variance (ANOVA) followed by Duncan at 5% level of confidence. RESULTS AND DISCUSSION Effect of Ratio of Oil to Water and Variations of Stabilizer Organoleptic response used is hedonic based on preference level of panelists for color, flavor, and aroma of VCO beverage emulsion. Effect of ratio of oil and water and the variation of the organoleptic stabilizers can be seen in Table 1. The results of statistical analysis showed that the ratio of oil to water, and the variation of stabilizer did not significantly affect the aroma, color and flavor of virgin coconut oil emulsion. Each treatment showed that the ratio of oil to water and stabilizer variation was not significantly different to the color of virgin coconut oil emulsion. Based on organoleptic all samples showed not significantly different. Samples with a ratio of oil to water (8:2), and variation of stabilizer (Tween 80 and lecithin) has an average value of 4.97 which was the highest value. Stabilizer does not really affect the color. According to Glicksman (1969), hydrocolloid does not contain ingredients that can cause discoloration on foodstuffs. Comparison of oil with water and a variety of stabilizer does not give a significant effect on the color, because the raw material is not a beverage emulsion which has a distinctive color, as well as a stabilizer (Tween 80 and lecithin) does not have a distinctive color, so that when mixed with will have non significant effect on the resulting product. According to Winarno (1992), the taste is very important to be considered in the manufacture of a product. Because the sense of smell is a mixture of responses, tasting, which is mixed by the impressions such as sight, touch and hearing that determines the value of the satisfaction of those who consume it. Therefore, by decreasing the parameters such as texture, appearance and color, hence diminishing the value of preference for flavors by the panelists. The taste is a combination of two elements, namely absolute and fragrant flavor or aroma. Desired flavor similar to the desired scent. The flavors which usually preferred are sweet, delicious and fun. Based on the method of hedonic organoleptic showed that the taste of the beverage emulsion which is most preferred by the panelists was beverage emulsions of oil and water with a ratio of 8: 2 and with stabilizer Tween 80:lecithin (U.S. Wheat Associates, 1983). The resulting aroma of this emulsion is mixed with the aroma of VCO and flavor of citric acid. The real difference that occurs in virgin coconut oil emulsion was due to influence of raw materials used. The more VCO is used, then the resulting aroma is getting stronger and preferred by the panelists. The less VCO is used, the resulting aroma is getting less favored by the panelists. Based on the analysis of the color, flavor and aroma of the virgin coconut oil emulsion, the best treatment was obtained by treatment of stabilizers Tween 80:Lecithin, with a ratio of water to oil (8:2). Effect of Sweetener Type and Concentration of Stabilizer Acid number Analysis of the acid number is done to look for changes in the free fatty acid (FFA) of VCO emulsion. It is related to the water content in the emulsion which was up to 15% of the total volume of the product. So there may be a process of hydrolysis on oil during 379
processing and storage. Free fatty acid is more easily oxidized than in the form of esters with glycerol. Besides, the presence of unsaturated fatty acids is high enough on the VCO which can stimulate the oxidation of the oil, so it will affect the quality of the oil emulsion. Statistical analysis showed that the interaction between the type of sweetener and stabilizer concentrations did not significantly affect the acid number of virgin coconut oil emulsion. The acid number is affected by the fatty acids contained in the materials. The type of sweetener used in the manufacture of VCO emulsion is a source of carbohydrates, not a source of fat, so no significant effect on acid number of virgin coconut oil emulsion. Similarly, the stabilizer used is not a source of fat. Thus, the type of sweeteners and stabilizer concentration used do not provide a real effect on the rate of acid of virgin coconut oil emulsion. Based on research conducted by Juliesta (2000), the acid number of red palm oil emulsion products during storage is equal to 0.245 mgkoh/g of oil. Acid number of VCO emulsion smaller than the red palm oil emulsion. The high acid number indicates high content of free fatty acids in emulsions compared to the standard VCO. The high acid numbers indicate the poor quality of the oil used. Statistical analysis shows the interaction between the type of sweetener and stabilizer concentrations did not significantly affect the FFA content of the VCO emulsion. Fat levels affect FFA content in the material. The type of sweetener used in the manufacture of VCO emulsion is a source of carbohydrates, not fat source so no significant effect on FFA of virgin coconut oil emulsion. Similarly, the stabilizer used is not a source of fat. Thus, the type of sweeteners and stabilizer concentrations used do not give real effect to FFA of virgin coconut oil emulsion. Changes in free fatty acids can be due to the hydrolysis reaction. The result of the hydrolysis reaction of pure coconut oil is glycerol and free fatty acids. This reaction will be accelerated by the factors of heat, water, acidity, and the catalyst (enzyme). The longer this reaction takes place, the more free fatty acids are formed. Products or food with a high acid number, is due to the amount of free fatty acids, oxidation and breakdown of fatty acid double bonds (Rangkuti, 2007). TBA (Thiobarbituric Acid) The results of statistical analysis showed that the type and concentration of stabilizer sweeteners had significant effect on levels of TBA, while the interaction did not significantly affect to TBA of VCO emulsion. Effect of sweetener to the VCO emulsion can be seen in Table 2. Table 2 showed the significant differences between the treatments of sweeteners on the TBA content of the VCO emulsion. The highest TBA content provided by honey and the lowest by sucrose. TBA content of the differences caused by the nature of the sweetener. In addition, TBA is also influenced by auto-oxidation reaction that occurs in the material. Auto-oxidation begins with the formation of free radicals caused by factors that can accelerate the reaction such as light, heat, peroxide or hydro-peroxide fat, as well as enzymes lipoxydase (Winarno, 1997). Table 3 shows that each treatment has a noticeable difference. This means that the concentration of stabilizer affected significantly on the content TBA of the VCO emulsion. The highest and the lowest TBA content given by the concentration of stabilizer and 0.25% respectively. 380
ph Statistical analysis showed that the sweetener type did not significantly affect the ph, but the concentration of stabilizer treatment, and interaction type of sweetener and stabilizer concentration significantly affect ph. Effect of sweetener type on ph beverage VCO emulsion can be seen in Table 4. Table 4 shows that the highest ph is given by the concentration of stabilizer, and the lowest by 0.25% of stabilizer concentration. The ph differences related to the nature of the stabilizing influence of ph levels on VCO beverage products. The lower the ph level owned by a food, the longer the shelf life of these materials, due to the ability of microorganisms to live and grow smaller at lower ph. Therefore, the acidity can be used as a parameter preservation (Winarno, 1997). ph value of the VCO emulsion products are also affected by citric acid added to the VCO emulsion. The influence of the interaction between the type of sweetener and stabilizer concentration on emulsion VCO can be seen in Table 5. Table 5 shows that the interaction between the type of sweetener and stabilizer concentration had significant effect on the ph of the VCO emulsion. The highest ph value of VCO emulsion was obtained from treatments of glucose with addition of stabilizer, as well as from treatment of honey with addition of stabilizer. Measurement of ph has decreased because the ratio of oil and water affected the increased levels of free fatty acids. Increased of acid due to oxidation and hydrolysis reactions of the oil. The new compounds resulting from the reaction is acidic, so it will lead to a decrease in the ph value of the product. Damage to oil due to oxidation and hydrolysis during storage will result in the formation of certain compounds which are auto-catalyst against further damage. This process will produce short-chain compounds which are acidic and thus lowering the ph. Viscosity In this study, although the sweetener is added in the same amount (10%), but each has a different role in determining viscosity. The influence of the interaction between the type of sweetener and stabilizer concentration on emulsion VCO can be seen in Table 6. Viscosity of VCO emulsion from all treatments were different caused mainly by differences in the type and concentration of emulsifier. It is also influenced by the concentration of the dispersed phase. A fairly high level of viscosity is very important to stabilize the emulsion, because the high viscosity can inhibit attractive forces between droplets that can cause emulsion aggregation or instability. Based on the results of chemical and physical analysis of the VCO emulsion on the second phase of the study, it could be concluded that the product of beverage VCO emulsion with treatments of sweeteners sucrose and stabilizer concentration was considered as the best/selected product. CONCLUSION 1. Treatments of oil with water (8 : 2) and the variation of stabilizer Tween 80 with Lecithin is selected as the best based on the oganoleptic. 2. The characteristics of the best VCO emulsion produced from treatments of sucrose and stabilizer (Tween80:lecithin) were as follow: the acid number of 0.008 mg KOH/g, 3.90% FFA, TBA 0.133 mg malonaldehyde/kg of oil, ph 3.98, and a viscosity of 27.67 d.pas. 381
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Tables Tabel 1. Organoleptic of virgin coconut oil emulsion. Ratio of oil with water Variation of stabilizers 6:4 Tween 80:Tween 20 Tween 80:Lecithin Tween 20:Lecithin 7:3 Tween 80:Tween 20 Tween 80: Lecithin Tween 20: Lecithin 8:2 Tween 80:Tween 20 Tween 80: Lecithin Tween 20: Lecithin Organoleptic scores Aroma Colour Flavour 3.95a 4.16a 4.42a 4.22a 4.91a 4.80a 3.78a 4.32a 4.36a 4.09a 4.62a 4.16a 3.96a 4.70a 4.55a 4.87a 4.69a 4.46a 4.31a 4.97a 4.22a 4.61a 4.63a 4.63a 4.40a 4.91a 4.90a Tabel 2. Effect sweetener to TBA of VCO emulsion. Sweetener TBA (mg malonaldehide/kg of oil) Sucrose 1.040 a Glucose 1.193 b Honey 1.374 c Tabel 3. Effect of stabilizer concentration to TBA of VCO emulsion. Stabilizer concentration (Tween 80:lechitin) TBA (mg malonaldehide/kg of oil) 0.25% 0.975 a 1.209 b 1.422 c Tabel 4. Effect stabilizer concentration on ph of virgin coconut oil emulsion. Stabilizer Concentration The average ph value 0.25% 3.81 a 3.88 b 3.93 c Remarks : Mean value with the same letters are not significantly at 5% by Duncan 383
Tabel 5. Effect of sweetener and stabilizer concentration on ph of VCO emulsion. Sweetener Stabilizer concentration (Tween 80:Lecithin) ph Sucrose 0.25% 3.67 a 3.98 c 3.87 bc Glucose 0.25% Honey 0.25% 3.91 bc 3.88 bc 3.91 bc 3.86 b 3.93 bc 3.85 b Tabel 6. Effect of sweetener and stabilizer on viscosity of virgin coconut oil emulsion. Sweetener Stabilizer concentration (Tween 80:Lecithin) Viscosity Sucrose 0.25% 28.00 bc 27.67 b 26.00 a Glucose 0.25% Honey 0.25% 28.00 bc 29.67 de 29.00 cd 30.67 ef 31.33 f 35.00 g 384