Analysing multivariate data from designed experiments: a case study of photo-oxidation in sour cream

Exposure to light induces photo-oxidation in dairy products, causing undesired offtaste/rancidity. In this case study we present the results of a designed experiment in four factors: illumination source, type of packaging, distance to illumination source and exposure time, in order to observe the resulting oxidation of low-fat sour cream, measured by fluorescence spectroscopy. Such spectroscopic data yield highly correlated response variables. A novel multivariate method, 50–50 MANOVA, is applied for the statistical analysis. The main objective is to present and interpret complex and comprehensive data results to researchers and practitioners in an informative way. The experimentation revealed that several factors and interactions must be taken into consideration when designing optimal environment for sour cream storage. Copyright © 2007 John Wiley & Sons, Ltd.