Survival analysis applied to sensory shelf life of yogurts - I: Argentine formulations

Sensory shelf lives of Argentine commercial stirred yogurts of different compositions stored at 10 degrees C were studied. Variations were as follows: fat-free and whole-fat, and vanilla and strawberry flavors. Yogurts were tested between 0 and 84 d of storage by consumers who expressed their acceptance or rejection of each sample; yogurts also were measured overall, as well as their attribute acceptability, with a hedonic scale. Survival analysis statistics were used to estimate shelf lives. Considering 25% of consumers rejecting the product, shelf lives were between 28 and 41 d; thus, a unique shelf life for this product does not seem reasonable. A log-linear model and a direct quantile comparison formula were introduced to analyze the effect of formulation on rejection time distributions and shelf life values, respectively. Overall, fat-free yogurts had lower shelf lives than whole-fat yogurts.