Monitoring Yogurt Culture Fermentation and Predicting Fermentation Endpoint with Fluorescence Spectroscopy

Abstract

Abstract. Determination of the endpoint of yogurt culture fermentation is a process parameter that could benefit from automation. The feasibility of using a fluorescence sensor technology based on 280 nm excitation and 350 nm emission to predict the endpoint of yogurt culture fermentation was investigated and compared with the endpoint prediction from a near-infrared (880 nm) light backscatter sensor. Yogurt cultures with three levels of milk solids (8%, 10%, and 12%) and three temperatures (40°C, 43°C, and 46°C) were tested with three replications in a 3 x 3 factorial design (n = 27). Prediction models were developed for each optical measurement using the independent variables and time parameters calculated from the data. It was found that the fluorescence sensor technology was able to predict the endpoint of yogurt culture fermentation with a standard error of 16.0 min and an R2 value of 0.999. The near-infrared sensor technology was able to predict the endpoint with a standard error of 10.4 min and an R2 value of 0.997.