Peranan kalsium dalam pemanjangan tempoh hayat payaya eksotika
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Date
1997-01
Authors
Ahmad, Ruzita
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Abstract
During the preliminary study, much work was carried out in collecting basic
data on the Eksotika papaya during ripening at ambient condition. Sensory
evaluations were also carried out to c~rr~late between panels' colour pe~~eption and
instrument (Hunterlab Colour Differencemeter) readings:- The data gathered will
enable a more objective grading system to be adopted for the Eksotika papaya. A
high correlation (r = 0.93) existed between colour index ( panel judgement) and the
Hunter-b value.
Eksotika papaya were later treated with hot water, infiltrated with calcium
chloride solution, and stored under modified atmosphere at l2°C. The hot water
treatment reduced rotting and delayed the loss of green colour but it did not improve
the texture of ripe papayas. Making a fresh cut on the stem helped in the absorption
of calcium solution. Most of the calcium was concentrated in the skin.
The addition of surfactant and starch on the papaya skin proved unsuccessful.
Infiltration of cold calcium chloride solution posed problems of chill-injured fruits.
The combination of calcium treatment and modified atmosphere storage extended the
shelf-life ofEksotika papaya up to 1 month.
During the preliminary study, brown and dry spots were observed on ripening
papaya peel. Examination under the light microscope of wax embedded samples
showed that the brown spots demonstrated disorganized epidermis cells and the dry
spots showed lignified tissues. Microscopic examinations also showed that both the
brown and the dry spots were not due to microbial attacks. Chilling injury symptoms
were also examined under the light microscope using the wax embedding method.
The following study was directed towards the effect of calcium on the ultra
structure of papaya tissue. Calcium treated and control tissues were observed with a
transmission electron microscope (TEM). Examination under the TEM showed that
calcium treatment did not affect the wax .layer. After I week·of storage, the cell walls
of treated tissues were more homogenous compared to control. The mitochondria of
calcium treated cells had distinct crista structures compared to control cells.
U1trastructural measurements were also done to observe the changes of the papaya
organelles during ripening.
Samples were also viewed under a scanning electron microscope (SEM) to
observe the ultrastructure of the papaya skin and flesh and also to locate calcium in
the papaya tissues. The elements present in the papaya skin were studied using SEM
coupled to EDX ( electron diffraction X-ray microanalysis). The elements present
were P, N, Ca, Mg, K, S, Cl and 0. SEMIEDX studies also showed the presence of
calcium at various depths of the papaya tissues. Calcium treatment increased the
calcium content of papaya tissues at the 0 -2 mm depth, but for greater depths,
calcium treatment did not significantly increase the papaya tissue calcium content.
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Keywords
Hayat payaya eksotika