Milk and Coconut Water Combination in Drink Yogurt Process Production on Total Solid, Viscosity and pH

Milk and Coconut Water Combination in Drink Yogurt Process Production on Total Solid, Viscosity and pH

Alifah Mafatikhul Jannah, Nurwantoro, Yoyok Budi Pramono

Faculty of Animal Husbandry, Diponegoro University, Semarang

INTRODUCTION

Milk has high nutrients, so milk is easily damaged (perishable food). The growth of spoilage microbes can be avoided by fermented milk. Especially for milk with total solid about 8.42% needed an appropriate treatment handling to prevent damage. One of milk diluted utilization is drink yogurt​. In this study, drink yogurt is made to utilize diluted milk as a yogurt diversification product to enhance the flavor of yogurt, to become not too sour, not viscous and easy to drink. Sometimes, the sour taste of yoghurt is less preffered by consumers. This drink yoghurt made from milk and coconut water combination. Coconut water is used as a diluent because most of its content is water. The sugars content in coconut water are glucose, fructose, and sucrose. Glucose and fructose in coconut water is monosaccharide which is expected to be utilized easier by lactic acid bacteria (LAB) than disaccharide.

The effect of milk and coconut water combination in drink yogurt process production can be seen from total solid content, viscosity and pH. The combination of milk and coconut water is expected to cause the low level of total solid, decrease the viscosity of yogurt or a more dilute, and the pH is higher than yogurt without coconut water. According these conditions, so the research about the effect of milk and coconut water combination on total solid content, viscosity, and pH value of drink yogurt is done.

The objective of this research is to determine the milk and coconut water combination on total solid content, viscosity and pH of  drink yogurt. The study outcome is expected to be useful to give the information and knowledge about the effect of milk and coconut water combination in  drink yogurt process production on total solid content, viscosity and pH, for utilizing diluted milk as raw material of drink yogurt, and to provide an alternative yogurt diversification product.

MATERIALS AND METHODS

The experiment conducted on October to November 2011 in Technology of Animal Products Laboratory, Department of Animal Production, Faculty of Animal Husbandry, Diponegoro University, Semarang. The ingredients used in this study are diluted fresh milk (total solid 8.42%), Lactic Acid Bacteria (LAB) starter cultures (Lactobacillus bulgaricus and Streptococcus thermophillus), and coconut water from coconuts with meat fruit thickness is 0.8 to 1.0 cm. The material used are jar, pan, measuring cup, spatula, refrigerator, incubator, thermometer, oven, erlenmeyer, scales, pH meter, beaker glass, porcelain bowl, desiccator, Ostwald pipe and picnometer.

The experimental design is using Completely Randomized Design (CRD) with 5 treatments and 4 replications. The treatment given are T0 (combination of milk and 0% (v/v) coconut water), T1 (combination of milk and 15% (v/v) coconut water), T2 (combination of milk and 30% (v/v) coconut water), T3 (combination of milk and 45% (v/v) coconut water), T4 (combination of milk and 60% (v/v) coconut water). The quality tested including total solid content (Legowo et al., 2005), viscosity (Sutiah et al., 2008), and pH (Wahyudi, 2006).

The data is statistically processed using analysis of varians at 5% levels. If there is a real effect on total solid content, viscosity and pH, the analysis is continued by Duncan Multiple Range Test (Steel and Torrie, 1995).

The Drink Yogurt Processing with Milk and Coconut Water Combination

The drink yogurt processing is made ​​by treating the combination of milk and coconut water according to the treatment (0%, 15%, 30%, 45%, and 60%). Milk and coconut water put in the jar and mixed until homogeneous. Then pasteurized at 80°C for 15 minutes and the temperature is lowered to 43^oC. Milk is inoculated with a starter as much as 3% v/v with the density of starter is 10⁷ CFU/ml. After that, it’s incubated at 43^oC for 4 hours until the acidity is about 0.7 to 0.9%. The drink yogurt produced is stored in a refrigerator at 5^oC.

RESULTS AND DISCUSSION

The average of drink yogurt data on total solid, viscosity and pH with milk and coconut water combination shown in Table 1.

Table 1. The average of Milk and Coconut Water Combination on Total Solid, Viscosity and pH Drink Yogurt

Treatment	Variables
	Total solid (%)	Viscosity (cP)	pH
T0 (0%)	7.20a	11.24a	4.34ns
T1 (15%)	7.06a	7.27ab	4.30ns
T2 (30%)	6.56ab	5.30bc	4.22ns
T3 (45%)	5.22c	3.08bc	4.33ns
T4 (60%)	5.43bc	1.79c	4.38ns

Information : The different superscript showed significantly (P<0,05); ns showed non significantly (P>0,05)

The Effect of Milk and Coconut Water Combination on Total Solid

The average value of total solid content of drink yogurt is between 5.22 to 7.20%, including aqueous and in accordance with the opinion of Kiani et al. (2008), that the total solid content of drink yogurt is about 4.50 to 7.00%. The total solid content of drink yogurt results is low, caused by low total solid content of the raw materials used in the drink yogurt process production. The total solid of fresh milk is 8.42% and coconut water is 5.70%. The low total solid content of drink yogurt is also affected by low levels of milk fat. Based on the research results, the levels of fat in fresh milk is low. Its about 0.11%. Fat content would affect the amount of total solid in milk. According to Ginting and Pasaribu (2005), low-fat milk has a more diluted texture, so it’s suitable to be used as the materials for drink yogurt.

The average of total solid content is not significantly different until T2 along with the increasing number of milk with coconut water combination. At T2 to T3, there is a significant difference, it’s expected that the LAB need more solid material in the coconut water and milk (lactose and casein) in the fermentation process. Low level of total solid causes the ability of LAB to produce lactic acid and fermentation metabolites are too low. Production of lactic acid and the fermentation metabolites produced in this study is low. It’s because of the low bacterial activity due to the change of the initial substrate from UHT milk substrate becoming a more dilute substrate (a combination of milk diluted with coconut water). According to Wahyudi and Samsundari (2008), during fermentation, lactose converted into lactic acid by LAB. The formation of lactic acid causes a decrease in pH, so it made the casein coagulated as gel. The gel formation causes the texture becoming semi-solid and it’s influenced by total solid, protein and homogenization process.

The Effect of Milk and Coconut Water Combination on Viscosity

The highest viscosity is at T0 and the lowest is at T4. The viscosity between 1.79 to 11.24 cP, it  is still in the normal standard, both in the yogurt without milk and coconut water combination (T0) and yogurt with milk and coconut water combination (T1, T2, T3 and T4). The viscosity of drink yogurt without milk and coconut water combination (T0) is in accordance with the opinion of Winarno and Fernandez (2007) which refers to the fermented product (yogurt) had a viscosity between 8.28 to 13.00 cP. Drink yogurt with milk and coconut water combination is in accordance with the opinion of Kiani et al. (2008), the viscosity of the drink yogurt is about 1.00 to 2.00 cP.

The result shows that the viscosity of drink yogurt  was not significantly different until T1, and becoming lower from 7.27 cP to 1.79 cP. The average of drink yogurt viscosity  decrease due to the low levels of total solid, especially in fat content of milk and coconut water. In accordance with the opinion of Sunarlim et al. (2007) that if the yogurt made from milk with low total solid, water content will increase, so that it will lead to the  decrease of  yogurt viscosity.

The low levels of total solid content in drink yoghurt cause the low formation of lactic acid by BAL. So, when the fermentation is on going, the coagulated casein by lactic acid is also low. Coagulation of casein will form a gel that can cause changes in the texture of yoghurt, the viscosity becomes lower or more aqueous. According to Wahyudi and Samsundari (2008), some of dry matter contents role on the fermentation process are lactose and casein. During the fermentation, lactose is converted into lactic acid. Lactic acid formed by LAB can cause casein coagulated become a gel. The formation of gel  cause the texture becomes semi-solid, so its viscosity is increased.

The Effect of Milk and Coconut Water Combination on pH

The average pH value of drink yogurt produced, both with coconut water (T1, T2, T3, T4) combination or without  coconut milk combination (T0) classified in normal range between 4.23 to 4.38 and it’s in accordance with Sanful (2009), that  pH of yogurt from the various levels of cow milk substitution with coconut milk ranged from 4.20 to 4.40.

The highest pH values is ​​found in the T4, it is 4.38 and the lowest are in T2 treatment, that is 4.22. Milk and coconut  water combination didn’t show a significant effect on the pH value. This condition caused by the formation of the pH value is influenced by the presence of LAB activity in lactic acid production in yogurt fermentation process. It is suspected that the lactose and casein in the milk is also low, and it causes the total solid  not optimal to the growth of LAB. In addition, low level of total solid causes the difference substrate for the LAB growth, so it causes the decrease of pH value on lactic acid fermentation not optimal and the pH values produced is relatively constant. The pH values ​​of drink yogurt is also influenced by the contribution of other organic acids besides lactic acid. According to Jene et al. (2004), the pH value measured is the hydrogen ion concentration in the form of dissociated, so not all acidic components measured. The relationship between pH value and total acid is not determined directly because the pH value is not only influenced by acid concentration, but also the type of acid, cations and other components (alkaline).

CONCLUSION

Based on the research results can be concluded that  drink yogurt with milk and coconut water combination (0%, 15%, 30%, 45% and 60%) is significantly affected the total solid content and viscosity, but not significant to the pH value. The greater the milk and coconut water combination, the lower the total solid content and viscosity, but the pH values ​​are relatively constant. The optimal combination of milk and coconut water in terms of expected  characteristics that have a low total solid content and low viscosity is in T2 (30%).

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