Biomedical Engineering Reference
In-Depth Information
compared to those picked on cool mornings, when stored for long periods at below
optimum humidity.
U SE OF F UNGICIDES
To control the spread of pathogens from infected to non-infected crops during storage
and transport, fungicides are used. Fungicides prevent fruit rots and decay in vege-
tables and fruits by controlling or killing Rhizopus spp. responsible for decay in
stone fruits and berries, Penicillium spp. on citrus and pome fruits, and Erwinia
carotovora (bacterial soft rots) on leafy vegetables and potatoes. Benomyl, thia-
bendazole (benzimidazole), and O-phenylphenate are the most common fungicides
used in citrus. Potassium sorbate added to the standard fungicide treatments of citrus
can reduce decay by as much as 35% beyond the level of protection provided by
fungicides. 190 Thiabendazole-treated sawdust was reportedly used to pack fresh
chestnuts to prolong storage life for at least 2 months. 191 By dipping commodities
in hot water with fungicides, diseases can be effectively controlled. Rotting, brown-
ing, and weight loss in lychees stored at 20 to 30°C can be controlled by benomyl
treatment (0.5% at 52°C for 2 min). 192 Kader 122 recommended a 5-min hot water
(51.5°C) dip with 500 ppm of benomyl for mangos, papayas, pineapples, and bananas
to prevent anthracnose, the most serious postharvest disease of tropical fruits. Methyl
bromide (MB) treatment of nectarines for export to Japan was investigated by Harvey
and co-workers 193 for control of codling moth. Treatment with 48 g MB/m 3 for 2 h
at 21°C controlled codling moth ( Cydia pomonella L.) and caused no significant
phytotoxic response in the cultivars studied (“Summer Grand”, “May Grand”, “Fan-
tasia”, “Fibre Brite”, “Red Diamond,” and “Spring Red”). All fumigated nectarines
were significantly firmer than those untreated after storage at 2.5°C for 7 days and
they ripened satisfactorily. Likewise, soluble solids content was not affected by
fumigation. Organic bromide residues were reportedly lower than the U.S. tolerance
of 20 ppm. Fumigation with sulfur dioxide (SO 2 ) has been a standard practice for
grapes to control decay caused by Botrytis spp. This is effectively controlled by
fumigating grapes immediately after harvest at a concentration of 0.2 to 0.5%, and
once every week during storage using a concentration of about 0.1%. 45
H OT W ATER T REATMENT
Dipping the produce in hot water is carried out to control surface and skin infections. 2
Hot water treatment (HWT) has been successfully used to control pest and insect
infestations in papayas, 194 mangos, 195 and ”Brazilian” bananas. 196 Fresh cucumbers
sometimes incur extensive heat damage when subjected to HWT causing surface
pitting, rapid chlorophyll breakdown, and increased susceptibility to disease. This
problem can be overcome if the fruits are first conditioned to 32.5 ± 0.5°C for 24 h 197
before hot water treatment at 45°C from 30 to 60 min., or at 46°C from 30 to 45 min,
which is also the range required to kill fruit flies. Two stages of hot water treatment
have been developed for papayas. 194 The first stage is the immersion of the fruit in
water at 42°C for 30 min, the second stage follows immediately uses water at 49°C
for 20 min. After HWT, the fruits are cooled with water spray at 20°C for 20 min
 
Search WWH ::




Custom Search