Hue Optical Properties to Model Oil Palm Fresh Fruit Bunches Maturity Index

摘要

Harvesting of the oil palm fresh fruit bunches (FFB) at correct stage of ripening is important in maximizing the quality of oil of the oil palm FFB. A non-destructive and real time simulation method is necessary to predict the FFB maturity stage while on the tree. Three colors form the basis for the RGB-colorspace and it can also be transformed into one common basis for the color space in HS1. In the HSI coordinate system, a color is described by its hue (average wavelength), saturation (the amount of white in the color), and intensity. This color space makes it easier to directly derive the intensity and color of perceived light. Furthermore it can be used as an optical property of digital value. The experiment was conducted to determine the Hue optical properties of the three categories of Fresh Fruit Bunches (FFB) namely unripe, underripe and ripe. Nikon Coolpix 4500 digital camera with tele-converter zooming and the Keyence vision system were used to capture the FFB images in actual oil palm plantation. The relationship of the oil content for mesocarp oil palm fruits with the digital value of Hue was analysed. The lighting intensity under oil palm canopy was simultaneously recorded and monitored using Extech Light Meter Datalogger. Using Analysis of Variance (ANOVA), the ratio of test statistic of F with F_(critical) for experiments under natural environment of oil palm plantation indicated the hue value was the best color digital component to differentiate the maturity level (unripe, ripe and overripe) of FFB in real time oil palm plantation. On the same day, the fruitlets were plucked from FFB and analysed for its oil mesocarp content using the Soxhlet Extractor machine. The calculations to determine the mesocarp oil content was developed based on the ratio of oil to dry mesocarp. The equation model obtained was Y = -0.0116X2 + 5.2376X - 514.88 and R~2 = 0.884. Y is the mesocarp oil content, X is the Hue value and R~2 is the Regression Squared respectively. From this finding, the knowledge based method can be developed for communication of management strategy of oil palm plantation by estimation the days harvesting of FFB with the highest oil content and quality in the fruit.