Comparison of quality attributes of mango fruits produced from two contrasting agro-ecological zones of Kenya
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Date
2014Author
Ouma, L.
Ambuko, J.
Shibairo, Solomon I.
Owino, WO.
Hutchinson, M.
Njuguna, J.
Books, Ruforum.
Sheets, Fact.
Oer, Ruforum.
Scarda, Ruforum.
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Mango (Mangifera indica) is a tropical fruit adapted to a wide range of agro-ecological
conditions. In Kenya, mango fruits are produced across various agro-ecological zones (AEZs);
from sub-humid to semi-arid. The diverse production conditions found in these AEZs variably
affects fruit growth and subsequently the postharvest qualities. This study was conducted to
compare the quality attributes of two mango varieties (‘Apple’ and ‘Ngowe’) produced
under two different AEZs. Embu County (a high potential AEZ) and Makueni County (a
low potential AEZ) are major mango-producing counties in Kenya. The study was conducted
over two seasons between 2013 and 2014. ‘Apple’ and ‘Ngowe’ mango fruits were harvested
from the two AEZs at four successive maturity stages; from the earliest physiological maturity
(stage 1) to the tree-ripened stage (stage 4). In stage 1 fruits, the flesh was mostly cream
and had just started turning yellow around the seed. The subsequent maturity stages were
determined at 10-day intervals from stage 1 as stages 2, 3 and 4. For all the maturity stages,
initial quality attributes were determined immediately after harvest and the again at a
predetermined end stage following ripening at ambient room conditions (Temperature: 25 ±
1
oC and RH: 60 ± 5%). The quality attributes determined include sugars (fructose, glucose,
and sucrose), °Brix, %TTA, vitamin C, beta carotene and mineral nutrients (Potassium,
Magnesium, Calcium). For sensory evaluation, diced fruits were scored for various attributes
including acidity, sweetness, mouth feel, flavor, aroma, color and general acceptability by a
panel of 33 untrained panelists. For all the parameters evaluated, there was significant
interaction (Pd”0.05) between maturity stage, variety and AEZ. Levels of TTA decreased
gradually with the stage of maturity irrespective of variety and AEZ. Overall, Embu fruits
had higher initial TTA levels for all maturity stages. Although Apple fruits (all stages) had
higher initial TTA, at the end of ripening TTA levels were relatively lower compared to
Ngowe. Initial beta carotene levels increased while vitamin C levels decreased with maturity
stage. Significantly higher beta carotene and vitamin C levels (initial and end stage) were
observed in Makueni fruits. Initial and end stage Ca, Mg and K levels decreased with
maturity stage, irrespective of variety or AEZ. Stage 1 and 2 fruits retained the highest Ca
and Mg levels at the end stage. The highest sugar levels and end stage 0brix levels were
observed in stage 4 fruits (regardless of AEZ and variety). Overall, Makueni fruits had
relatively higher end stage 0brix levels compared to Embu fruits. In ‘apple’, Makueni fruits
scored higher than Embu fruits for all the sensory attributes. On the contrary in ‘Ngowe’,
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