Modelling the colour of strawberry spread during storage, including effects of technical variations

The colour of freshly processed strawberry spread changes relatively rapidly from a bright red to a dull red, which then makes its appearance generally less acceptable for consumers. The colours of strawberry spreads following several processing conditions were measured under different storage conditions. Additional sugar and colorant had only slight effects on the colour decay, while exclusion of oxygen and daylight did not affect this process. The only condition that clearly maintained the freshly processed appearance was storage at 4°C. Hexagonal bottles were filled with the strawberry spreads and their colour was repeatedly measured at the six sides of the bottles, using a Minolta chroma meter. Data were analysed using non-linear indexed regression analysis based on a logistic function for the three colour aspect of a∗, b∗ and L∗. This technology allowed the determination of the variation in these data in terms of improved reliability (R² _adj, >90%). It also allowed better interpretation of the processes involved. All variations in the data could be attributed to technical variation.