The aim of this research was to determine the sample size (number of fruits) needed to estimate the average of Royal Gala and Fuji apples characters, evaluated at harvest and postharvest, after a period in cold storage. In Royal Gala and Fuji apples were measured eight characters at harvest and 11 after could refrigeration. For each character in each cultivar, measured at harvest and after cold storage, was calculated the mean, variance, coefficient of variation, skewness, kurtosis and checked the normality and, then, was calculated the sample size. Larger sample sizes are needed to estimate the average of: ethylene production, ratio, respiration, weight and acidity. Smaller sample sizes are needed for the measurement of longitudinal diameter, pulp firmness, total soluble solids, transversal diameters (major and minor) and juice content. The sample size required to measure the characters of Royal Gala apples is lower than that required for Fuji apples. In Royal Gala and Fuji apples, 88 and 190 fruits, respectively, are sufficient for the measurement of characters, at harvest and after cold storage, with estimation error of 5% of the average.
Malus domestica; sampling; experimental design; post-harvest
