Investigation of Okra Pectin at Different Harvest Maturity
Abstract
Okra (Abelmoschus esculentus) is a staple vegetable in Ghana and several African countries but underutilized. The mucilage or pectin content is currently of interest for various food and non-food applications. The objective of this work was investigate the yield and intrinsic viscosity of okra pectin extract as influenced by fertilizer application and maturity of the fruit pods. Isolation of okra pectin was done by an aqueous extraction at pH 6.0 from the pods of 2 different okra genotypes at three harvest maturity and two different weight of NPK applications (6g and 9g). The intrinsic viscosity [η] of the okra pectin solutions was determined at 20oC with a Ubbelohde capillary viscometer and calculations made according to the Huggins equation. Pectin yield ranged between 8-24% depending on genotype, fertilizer treatment and maturity of the fruits. There were significant differences (p < 0.05) in the pectin yield between the okra genotypes as well as among the stages of maturity of the okra fruits. Interaction between okra varieties and the stages of maturity of fruits was also significant for pectin yield. The pectin yield of AGRA genotype was higher than that of AGBAGOMA. However, the intrinsic viscosity of pectin of AGBAGOMA was higher than that of AGRA. Highest pectin yield was observed for intermediate matured fruits, followed by that of immature fruits and lowest was observed for overgrown fruits. The intrinsic viscosity values however was highest for immature fruits as compared to the intermediate and overgrown okra fruits. Pectin yield and intrinsic viscosity increased significantly with fertilizer application (p < 0.05). The present findings show that harvesting at intermediate maturity would be most appropriate if high pectin yield is desired. A 9g NPK treatment suggest the opportunity to increase yield and intrinsic viscosity of okra pectin. The study showed that it is important to identify the most appropriate stage of development to harvest the okra fruit for maximize pectin yield. The results of this study suggest that intermediate fruit maturity would be most appropriate to harvest okra fruits to increase pectin yield.
Description
A thesis submitted to the Department of Food Science and Technology, College of Science, in partial fulfilment of the requirements for the degree of Master of Science in Food Quality Management,