Impact of Blanching on Colour Development in Clove (Eugenia caryophyllus) Processing

Abstract

External colour of dried clove (Eugenia caryophyllus) is a crucial factor for determining quality, grade and price in the market. Production of high quality clove which is reddish brown to blackish brown in colour, is a constraint with conventional sun drying technique. Therefore, the objective of this study is to find out the applicability of blanching technique to produce higher quality clove having reddish brown to blackish brown external color without volatile oil loss. Randomly selected fresh clove buds were subjected to blanching in hot water at different temperatures (70 °C to 100° C) and different time periods (10 seconds to 135 seconds) and dried under sun drying. The experimental design was Completely Randomized Block Design (CRD) with thirteen treatments and five replicates. The colour of the dried clove was determined by visual inspection. Moisture content and oil content of dried clove which were determined according to Association of Analytical Communities (AOAC) Official Methods no 986.21 and no 962.17m respectivel. Results showed that ten treatments out of thirteen treatments gained favorable colour development. The mean oil content in dried clove produced by 2 treatments; namely T7 (Blanching at 80 °C for 30 seconds) and T8 (Blanching at 80 °C for 60 seconds) out of above ten treatments, did not show any significant (p<0.05) oil loss in comparison to the control (un-blanched). In conclusion, the high quality clove which retains blackish brown to reddish brown colour can be produced by blanching fresh cloves at 80 °C for 30 to 60 seconds without any significant volatile oil loss.