THE OPTIMUM CONDITION OF MILK BEVERAGE SUPPLEMENTED WITH COFFEE BY RESPONSE SURFACE METHODOLOGY


Ahn S., Park J., Yoon J., Park S., Kim G., Jhoo J.
Kangwon National University, South Korea

Introduction:
Recently, it is tendency to increase the consumption of milk beverage more than milk or other milk products. However, its precipitation becomes issue during storage or distribution because it has various ingredients, and it is needed to determine suitable emulsification condition to solve the issue. Therefore, this study was carried out to determine the optimum condition for emulsification of milk beverage supplemented with coffee.

Methods:
Four kinds of emulsifiers were used in this study, such as sucrose fatty acid ester F110, sucrose fatty acid ester F160, Almax 9280, Almax 9080, and its HLB value were 11, 15, 7.5, and 14.5, respectively. To manufacture the milk beverage, some materials were used as follows: raw milk, coffee extracts, skim milk powder, cream, emulsifier, and so on. High speed homogenizer was used for primary emulsification, and high pressure homogenizer was used for secondary emulsification to disperse into nano size. To determine the most efficient conditions for the emulsification, the speed of primary homogenization and the amount of emulsifiers were investigated by response surface methodology. Particle size distribution and z-potential were measured to select suitable emulsifier and to investigate the manufacturing condition of the beverage. To observe the distribution and shape of the particle, the milk beverage was observed with optical microscope.

Results:
It was revealed that the particle size of the group added sucrose fatty acid ester F160 was significantly bigger than others (p<0.05). Also, there were not significant differences in z-potential. Sucrose fatty acid ester F110 and F160 were powder type, whereas, Almax 9080 and Almax 9280 were gel type emulsifiers which had strong viscosity. Because of it, they were not easy to handle in the manufacturing process. Therefore, sucrose fatty acid ester F110 was selected as suitable emulsifier in this study. With the results from response surface methodology, as speed of primary homogenization was decreased, particle size was increased, and z-potential was decreased. At the amount of emulsifier with 0.2071%, it was predicted that z-potential was the highest with approximately -32.62 mV, and particle size showed a tendency to decrease. Finally, the optimum conditions of primary homogenization speed and amount of emulsifier to manufacture the milk beverage were found to be 5,000 rpm and 0.2071%, respectively. After optimization of the condition, the beverage was manufactured to confirm it. The average particle size of the beverage was about 176.65 nm, and z-potential was -32.56 mV under the optimum condition. Every particles of the beverage in the optimum condition was round shaped, and evenly distributed in the micro photograph of the milk beverage. Generally, it is known that the absolute value of z-potential greater (30 mV or more), a colloidal system has better dispersibility.

Discussion:
Based on the data obtained from this study, it was considered that dispersibility of the beverage under the optimum condition was good enough to maintain its disperse system, and it is respected that the milk beverage supplemented with coffee can effectively be produced with this optimized condition.

Keywords: Response surface methodology, Emulsification, Probiotics, Milk beverage, Z-potential, Coffee

Citation:
Ahn S., et al. (2016). The optimum condition of milk beverage supplemented with coffee by response surface methodology. Conference Proceedings of IPC2016. Paper presented at the International Scientific Conference on Probiotics and Prebiotics, Budapest (p. 83.). IPC2016

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