Biological Variance, Burden or Benefit

Based on theoretical considerations, a new approach to deal with the variation in properties and quality attributes inherently occurring in all products and batches is presented. It leads to a better understanding of the processes involved and enables the mathematical description and modelling of the observed phenomena. The effect of variation in harvest maturity on the composition of batches drawn from a larger population is used as an example to elucidate the effects of external conditions. These external conditions include the rate constant of the process (directly linked to temperature and controlled atmosphere (CA) conditions), the magnitude of the variation in the larger population and the size of the batches. These theoretical examples show that the standard advice of statisticians to increase the number of individuals in a batch or sample does indeed increase the reliability of data analysis based on mean values. It also shows that the so obtained estimate may well give a complete false picture of the real value. An overview is given for ways to avoid the generation of biological variance, as well as ways to decrease the effects of biological variance already present. This new approach shows how biological variance should be tackled, and even possibly turned into a benefit. A number of practical examples is provided and described briefly to underpin the validity of the approach presented. These examples relate to sources of variation (sweetening of potatoes), to the behaviour of variation during postharvest treatment (colour of apples, keeping quality of cucumbers) and to sophisticated means of dealing with biological variance without too much explicit knowledge of the mechanisms involved (dynamic control system, soil irrigation)