Optimization of Manufacturing Conditions for Improving Storage Stability of Coffee-Supplemented Milk Beverage Using Response Surface Methodology

Abstract

This study aimed at optimizing the manufacturing conditions of a milk beverage supplemented with coffee, and monitoring its physicochemical and sensory properties during storage. Raw milk, skim milk powder, coffee extract, and emulsifiers were used to manufacture the beverage. Two sucrose fatty acid esters, F110 and F160, were identified as suitable emulsifiers. The optimum conditions for the beverage manufacture, which can satisfy two conditions at the same time, determined by response surface methodology (RSM), were 5,000 rpm primary homogenization speed and 0.207% sucrose fatty acid emulsifier addition. The particle size and zeta-potential of the beverage under the optimum condition were 190.1 nm and - 25.94±0.06 mV, respectively. In comparison study between F110 added group (GF110) and F160 added group (GF160) during storage, all samples maintained its pH around 6.6 to 6.7, and there was no significant difference (p<0.05). In addition, GF110 showed significantly higher zeta-potential than GF160 (p<0.05). The particle size of GF110 and GF160 were approximately 190.1 and 223.1 nm, respectively at initial. However, size distribution of the GF160 tended to increase during storage. Moreover, increase of the particle size in GF160 was observed in microphotographs of it during storage. The L* values gradually decreased within all groups, whereas the a* and b* values did not show significant variations (p<0.05). Compared with GF160, bitterness, floating cream, and rancid flavor were more pronounced in the GF110. Based on the result obtained from the present study, it appears that the sucrose fatty acid ester F110 is more suitable emulsifier when it comes to manufacturing this beverage than the F160, and also contributes to extending product shelf-life.

Improving the Quality of Response Surface Analysis of an Experiment for Coffee-supplemented Milk Beverage: II. Heterogeneous Third-order Models and Multi-response Optimization

“…In Ahn et al (2017), at their optimum point, their Y 1 value was 190.1 and their Y 2 value was −25.94±0.06, whereas, at our predicted optimum point, the predicted Y 1 was 183.4 and the predicted Y 2 was 30.93. We can see that our predicted minimum of Y 1 is smaller than their observed Y 1 , and our predicted maximum of Y 2 is greater than their observed Y 2 .…”

“…In Ahn et al (2017), the optimization objective was to minimize Y 1 (particle size) and maximize Y 2 (zeta-potential) simultaneously. For this multi-response optimization, we modified the desirability function technique of Derringer and Suich (1980).…”

“…Data analysis should include data screening, which is necessary for accurate modeling. The original data to be used for re-analysis is the data described in Ahn et al (2017), in which they tried to optimize manufacturing conditions for improving storage stability of coffee-supplemented milk beverage by using RSM. Through data screening, one outlier was deleted from their data (Rheem and Oh, 2019).…”

“…A dataset, which is obtained through the screening of the data in Ahn et al (2017), will be re-analyzed for the illustration of the remedy suggested in this research note. Since Ahn et al (2017) has two responses and a purpose of it is the multi-response optimization of them, this research note, which is a continuation of Rheem and Oh (2019), will model both responses by using heterogeneous third-order models, and optimize them simultaneously by employing the desirability function technique.…”

Improving the Quality of Response Surface Analysis of an Experiment for Coffee-Supplemented Milk Beverage: I. Data Screening at the Center Point and Maximum Possible R-Square

“…This research was motivated by our seeing a situation where a serious outlier at the center point exists and it is overlooked, and, accordingly, a statistically insignificant model was fitted to the data. Such a situation took place in Ahn et al (2017) , whose data will be re-analyzed for the illustration of the remedy suggested in this research.…”