Biomedical Engineering Reference
In-Depth Information
125 min with an airflow of 0.4 m
3
/s. The quality was not adversely affected with
the treatment, although weight loss was higher.
V
APOR
H
EAT
T
REATMENT
Vapor heat treatment (VHT) is the heating the fruit with warm saturated air at
temperatures between 40 and 50°C as a quarantine treatment to kill fruit fly eggs
and larvae before shipment to fresh markets.
206
Heat is applied directly to the surface
of the fruits by condensation of water vapor. This technology had been adopted for
mangos due to the banning of ethylene dibromide (EDB) as a fumigant. Ilangantileke
and Maglente,
207
who studied the applicability of VHT in controlling fruit fly in
mango cv. Nang Klang Wan, reported that it was effective in preventing the hatching
of eggs of
Dacus dorsalis
at time-temperature combinations of 48°C for 30 min or
46°C for 1 h. VHT reduced the firmness of mangos, in all time-temperature combi-
nations and delayed the incidence of fruit decay. There was insignificant weight loss
and better peel yellowing and the fruits had acceptable organoleptic properties. VHT
has been used commercially in the Philippines to control oriental fruit fly on mangos
exported to Japan. Carried out in a VHT chamber, the treatment consists of exposing
the fruits to steam at 45.6°C for 10 min, then cooling the fruits by cold water and
air to 5°C. Internal breakdown in the flesh of ripened mango was a problem in the
initial stages of its use. However, it has been solved by carefully implementing the
time-temperature regimes and is now routinely used for quarantine treatment. VHT
has been used successfully with Florida grapefruit on a laboratory scale.
205
The
treatment conditions were vapor heat for 5 h at 43.5°C and relative humidity of
100%. Reduction of peel pitting after storage at 10°C for 4 weeks and 21°C for
1 week was an obvious benefit of VHT. No peel discoloration or rind breakdown
was observed. Quality parameters of “Arkin” carambolas were not affected after
vapor heat treatment using temperatures of 43.3 to 43.6°C for 90 or 120 min or 46.0
to 46.3°C for 60 or 90 min. Hallman
198
noticed that VHT caused duller color and
weight loss was greater after treatment at 46.0 to 46.3°C.
R
EFRIGERATION
Fruits and vegetables are usually stored above their freezing point and at tempera-
tures above chilling injury to maintain their freshness. Recommended storage con-
ditions for potatoes vary according to the end use. Table potatoes are stored at
temperatures of 4 to 7°C temperature and relative humidity of 95 to 98%. Processing
potatoes, i.e., chip potatoes, are stored at 10 to 12°C and 95 to 98% RH. Seed
potatoes are stored at 0 to 2°C at 95 to 98% RH.
128
The recommended airflow is
24 to 32 m
3
/h/ton, which is sufficient to maintain a good temperature distribution in
the bulk store and flush out CO
2
. Recommended storage condition of guava for an
assured storage time of 2 to 3 weeks is at temperatures between 5 to 10°C and
relative humidity of 90%.
208
Vasquez-Ochoa and Colinas-Leon
138
reported that the
storage condition for guava is at 7°C and 80% relative humidity which can be stored
for 3 weeks at the color-turning stage when harvested. The recommended storage
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