Apple Bruising Research Update: Effects of Moisture, Temperature, Cultivar
Bruise Susceptibility Results
We ran experiments to measure bruise susceptibility (bruise volume divided by impact energy absorbed, milliliter/Joule) versus storage humidity, temperature and cultivar (Red and Golden Delicious). We also measured both firmness and susceptibility over time.
Figure 1 shows humidity effects on the bruise susceptibility of Red and Golden Delicious apples.1 The 50% relative humidity resulted in significantly lower bruise susceptibility than in the other humidities for both cultivars in this experiment
Figure 2 shows temperature effects on bruise susceptibility. Warming both cultivars to at least 60°F significantly reduced bruise susceptibility. In Figures 1 and 2 Reds were more bruise susceptible than Goldens. This was true also when the data were pooled across the whole experiment (Figure 3) and agrees with bruise threshold results from Michigan State University (Schulte et al. 1992).
This was true also when the data were pooled across the whole experiment (Figure 3) and agrees with bruise threshold results from Michigan State University (Schulte et al. 1993).
Figure 4 shows the change in apple firmness over the 5 weeks of the experiment for all of the apples stored at 100% relative humidity. While the Magness-Taylor firmness decreased significantly, the bruise susceptibility did not. So the bruise susceptibility was independent of the apple firmness, at least in this experiment.
See Apple Bruising Research Update: Packingline Impact Evaluations, p. 12
1In the graphs, the vertical lines are 95% confidence intervals. Generally, if an average value lies within the confidence interval of another, then those two averages are not significantly different.
Weihua Zhang and Gary M. Hyde
Agricultural Engineering, Washington State University, Pullman
Tree Fruit Postharvest Journal 3(3):10-11