Harvesting, Handling and Transportation
Harvesting of fruits in India is mostly done manually by means of curved knife,
scissor or blade attached to a hanging basket to the distal end of bamboo sticks. Harvesting is
done on the basis of maturity level. Depending upon the end use of the harvested fruits, i.e.
market, export, processing etc., the degree of maturity is selected. Degree of maturity is
indicated by total soluble solid, acid/sugar ratio, firmness, starch content, fresh coloour, pulp-
peel ratio, days after fruit set, skin colour, etc. Based on these parameters and end use,
optimum-harvesting time can be determined.
After harvest, grading is required to fetch better prices for the produce. Usually,
grading is not a common practice in our country but with increasing quality consciousness
among consumers, grading is becoming an important unit operation. It includes removal of
infected, deformed and rotten fruits and separation of fruits in different categories based on
physical and maturity parameters, and market demand.
Certain pre and post harvest treatments enhance the shelf life of the perishable
commodity. Pre-harvest treatments are mainly meant to control infection/disease before and
after harvest. Post-harvest treatments are performed to increase maturity period of harvested
fruits. Chemical, thermal and radiation treatments are commonly performed to lengthen the
ripening processes. Another protective measure is wax coating.
Transportation contributes the most (15%) to the total postharvest losses. It varies
from 6 to 31% depending upon the fruit and variety. In order to reduce the losses, packaging
of fruits is essential. Type and material of packing differs for fruits and cultivars. Commonly
used materials are bamboo baskets, wooden crate, mud pots, jute bags, corrugated fibre-board
(CFB) boxes, card-board boxes, corrugated paper boxes, polyethylene bags, etc. Some
cushioning materials used are grass, stems, leaves, paper spacing, saw dust, pulp tray, tissue
paper, newspaper and straw. CFB boxes are suitable for packaging citrus fruits. Wrapping
with paper and poly bags retards the respiration rat thus increases the shelf life. Replacement
of wooden boxes is also being considered due to excessive deforestation and for maintaining
the ecological balance.
Transportation in India is mainly done by rail or road, occasionally by air and water
ways. Mode of transport are rail cars and trucks. As these means are not exclusively meant
for fruits/perishables, losses are increased. Still today, rail coaches used are close
compartments, without low temperature facilities, and proper ventilation. Similarly, there is a
scarcity of refrigerated vans for road transport. Advance packaging methods have
considerably reduced transportation losses but it is still a major cause of losses. Refrigerated
rail or road vans can be a better mode of transportation than the present rail or road cars
which are jerk prone, causing damage to the commodities. Hand loads and bullock carts also
reduce the losses but can only be exploited to a limited extent.
Storage
Storage of fruits is required to avoid glut in market during production peak and to
make the fruits available throughout the year. Fruits are perishable and difficult to store, thus
leading to considerable losses. The most successful methods of fruit storage are as follows:
i) Storage at low temperature
The Indian climate is characterized by high temperature and humidity which
provides conductive environment for fungal growth and disease or insect infestations
resulting into higher storage losses specially for fresh products. Respiration rate is at
its highest at time of harvest and it is reduced when the material is kept in refrigerated
storage. Refrigeration reduces the build up of respiration heat, thermal decomposition,
microbial spoilage which are main causes of quality degradation. The rate of cooling,
storage temperature, relative humidity, rate of CO2 accumulation, pre-packing, air
distribution system and utilization of storage space are other factors which influence
the storage life. Optimum refrigerated storage requirements for different fruits are
worked out at research centres such as CFTRI, Mysore. Some treatments for
refrigerated fruits enhance the storage life.
ii) Evaporative cooling chamber
The main purpose of the structure for evaporative cooling is to keep the
commodity fresh during the summer season. The structure is composed of a single
layer bricked floor. Double side wall is provided with 7.5cm spacing. Sand is filled in
between the two walls and the outer side is covered with bamboo and gunny cloth.
The chamber is kept cool by sprinkling water over the surface of the structure.
iii) Controlled /modified atmosphere storage
The most common and popular method for storage of perishables in India is
low temperature storage, but due to scarcity of electricity and the high cost of
operation and maintenance, this system can only be explotted to a limited extent. To
overcome the situation, several attempts have been made to develop controlled
atmosphere (CA) storage.
It was observed that low concentration of oxygen and high concentration of
carbon dioxide retard effectively the ripening processes. Reduction in oxygen level
below 8% and /or elevation of carbon dioxide level above 1% retards fruit ripening.
Two percent O2 is usually the lower limit tolerated by most fruits. Below this O2
level, anaerobic respiration may result in off-flavours and odours. Fruit exposed to
such low levels of O2 may loose their ability to ripen uniformly and normally after
removal from CA. Most fruits tolerate upto 5% CO2 but some show CO2 injury at
this level. Some fruits like sweet cherries and strawberries may tolerate 10 to 20%
CO2. Reduction of O2 and elevation of CO2 delays fruit ripening, reduces respiration
and ethylene production rates, retards softening and also slows down all
compositional and biochemical changes associated with ripening.
iv) Irradiation of fruits
Irradiation was tested as a quarantine treatment method. X-rays and gamma
rays are commonly used for the purpose. These are electromagnetic radiations of short
wavelength. Gamma rays are produced by cobalt-60. The source is kept under deep
concrete water pool. The fruits, to be irradiated, are passed through concreted tunnel,
on conveyor, exposed to gamma radiation. The dose is determined by cobalt strength
and exposure time. It was found as an effective means to lengthen the ripening time
by reduction in respiration rate, enzyme activities and freedom from infestation or
diseases to meet quarantine regulations.
