Reflectance Measurements of an Apple and Pear, and Prediction of Elapsed Days by Multivariate Analysis

Introduction

Fruit gradually undergoes change with the passage of time after harvesting. Examination of how the physical properties of fruit change over time is important, but if testing requires cutting out a portion of the fruit sample, the number of samples tested would most likely be greatly reduced. Non-destructive fruit properties inspection testing is commonly conducted using a spectrophotometer, and testing of sweetness and acidity by this means is well known. This type of testing is valuable not only for understanding the physical properties, but for quality management as well. Ripeness, in particular, can be judged based on the number of days that have elapsed from the time of harvesting from the tree. Fruit ripeness is known to be associated with the change in chlorophyll content. Here, we conducted a simulation experiment in which we investigated the time-course changes in purchased fruit samples over a period of days, focusing on changes in the absorption peak of chlorophyll. The results of measurement of apple and pear samples using a UV-VIS-NIR spectrophotometer revealed a correlation between the reflectance spectra of the samples and the number of days elapsed from the time they were obtained. Applying multivariate analysis, we used a prediction formula to calculate and predict the number of elapsed days from the time the samples were obtained. Good results were obtained with the apple sample, as reported in this paper.

May 22, 2013 GMT