Avocado (Persea americana) is one of popular fruits in Indonesia because of its taste and high antioxidant content. However, research on avocado in Indonesia is still limited. Grading avocados is still undertaken manually by squeezing the fruit to find its hardness and determine the ripeness level while it is already well known that image processing may play an important role in maintaining consistency in grading fruits. This study aims to determine the ripeness level of avocado by using Total Dissolved Solids (TDS), moisture content, and hardness as the parameters, and to determine the correlation between the ultraviolet (UV) reflection and the ripeness level of avocado. The study consists of non-destructive method and destructive method. The first was done by taking pictures/images of avocados surrounded by 4 UV lamps using a Digital Single Lens Reflex (DSLR) camera. There were 120 samples of avocado fruit with 4 levels of ripeness, 30 each, which were obtained from the Puncak area, Bogor. Immediately after completing the image taking, the destructive method was carried to determine the TDS, moisture content, and hardness of each sample. The lab test results were then used to obtain an equation that estimates the ripeness level, expressed in age (days) before ripening, by using multiple linear regression analysis. The resulted equation is having R-Square of 0.81, which mean that the parameters can be used to determine the ripeness level. The image data were processed further to get the values of Hue (H), Saturation (S) and Intensity (I) at each ripeness level, and from those values their determination coefficient which show the feasibility of the value to represent the ripeness of the avocado were determined. The result shows that the highest determination coefficient was that of I (intensity) of about 0.8191. The results of non-destructive and destructive method then was correlated each other to show the feasibility of using nondestructive method in estimating the ripeness level of avocado. The result shows that the usage of UV reflection, especially the value of intensity, for determining the ripeness level of avocado is feasible.
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