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Studies on the Meat Fiber of Different Coconut Varieties
Dissertation Abstract:
The coconut endosperm cell wall, known as coconut meat fiber, was isolated and studied for its physical and chemical characteristics in order to explain the nature of dietary fiber in coconut and its behavior in food formulation. With the increase in maturity, the neutral detergent fiber content of coconut flour increased in the normal varieties and decreased in makapuno. The acid detergent fiber increased in normal coconut while that in makapuno did not show considerable variation as the nut matured. The total carbohydrate content of normal coconut endosperm varied from 59.95 to 77.39 percent at 7 months to 71.02 to 81.04 percent at 12 months.
In all the varieties studied, mannose. glucose, and galactose were found to be the major sugar components of the coconut endosperm cell wall, while rhamnose, arabinose, and xylose were also present.
The water soluble polysaccharide of the cell wall was predominantly galactomannan, with galactose and mannose occurring at a ratio of 1:2. This fraction was 38.85 percent greater in makapuno than in the mature normal nut where values ranged from 6.87 to 12.43 percent depending on the variety. The cell wall of the seven-month-old Laguna Tall Green nut contained 22.70 percent of this water soluble polysaccharide.
Scanning electron microscopy examination revealed that the makapuno cell wall had smoother surface than the normal nut cell wall which was more rigid. The effect of extractions with hot water, EDTA, KOH, and NaOH on the cell walls of mature Laguna Tall Green and makapuno reduced the cell wall in terms of thickness but integrity was retained.
The X-ray diffraction patterns showed higher relative crystallinity in the cell wall of the manure nut compared with that of a young nut. The crystal peaks of mature cell walls showed 5.60 A°, 4.90 A°, 4.48 A°, 4.33 A°, 3.80 A°, 3.52 A°, 3.27 A°, 3.01 A°, and 2.70 A°, d-spacing. The effect of extraction with hot water and EDTA showed that crystallinity was still present; however, continued extraction with KOH and NaOH removed it. X-ray diffraction pattern of the cell wall in the wet condition resulted in removal of the crystallinity.
Ball milling increased the sensory acceptability value by reducing grittiness in bread preparations in which bread flour was substituted with coconut flour at a level of 20 percent. Extrusion cooking did not result in any appreciable level of neutral and acid detergent fiber content of coconut flour.