A comparative evaluation of maturity indices of mango fruits produced in two contrasting agro-ecological zones of Kenya
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Date
2014Author
Ambuko, J.
Ouma, L.
Shibairo, Solomon I.
Hutchinson, M.
Njuguna, J.
Owino, WO.
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Harvesting mango (Mangifera indica) fruits at the right stage for the destination market
and use requires reliable maturity indices. There are various indices that are used to determine
harvest maturity for mango fruits. However, differences in cultivars and growing environment
affect the reliability of these indices. The present study was conducted to establish maturity
indices of two popular mango varieties, ‘Apple’ and ‘Ngowe’. The study was conducted in
two contrasting agro-ecological zones (AEZs) of Kenya namely Embu County (a high
potential AEZ) and Makueni County (a low potential AEZ). For each variety, the earliest
physiological maturity was determined using flesh color. The flesh color was established by
cutting the fruits longitudinally to expose the cross sectional view. The earliest physiological
maturity (stage 1) was marked as the stage when the flesh was mostly cream and turning
yellow at the seed. The number of days after full bloom was matched to this maturity stage
(stage 1) and subsequent maturity stages determined at 10-day intervals as stages 2, 3 and
4. For each of the maturity stages, physiological (ethylene evolution and respiration rates);
physical (size, peel/flesh firmness and peel/flesh color) and biochemical (Total soluble solids
- TSS, Total titratable acidity – TTA and TSS:TTA ratio) maturity indices were determined.
The results show that in both varieties (‘Apple’ and ‘Ngowe’) from both locations (Embu
and Makueni), respiration rates increased gradually with maturity. ‘Ngowe’ and Makueni
fruits registered the higher respiration and ethylene evolution rates compared to ‘Apple’ and
Embu fruits for the same maturity stage. As maturation progressed, peel firmness decreased
gradually irrespective of variety or production location. In all fruits, flesh color (hue angle)
decreased gradually with maturity. Total soluble solids increased while TTA decreased
gradually with maturity. Overall, in both varieties, Makueni fruits attained comparable maturity
indices to Embu fruits at an earlier stage/date. The results revealed the significant effect of
production location on the maturity indices of mango fruits. There is need for additional
studies to establish
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