By Allah Dad Khan

Present Situation of Post Harvest

Losses in Fruit and Vegetables

Agro climatic condition of Pakistan

Agro-climatic conditions of Pakistan ranging

from tropical to temperate allow growing 40

different kinds of vegetables and 21 types of

fruits. Major vegetables grown in Pakistan include

potato, onion, chilli, melons, cucurbits, tomato,

turnip, okra and pea, whereas citrus, dates,

mango, guava, apple, banana, apricot, grapes,

almonds, peach, plum and pomegranate are the

main fruit crops. At present area under fruits and

vegetables is 0.995 million ha (4.3% of the total

cropped area) with the total production of 10.992

million tonnes

Magnitude of Post Harvest

In Pakistan the magnitude of post harvest losses

of vegetables and fruits is about 35%. Efforts are

being made both at federal and provincial level to

minimize these losses to safe guard the interest

of growers, processors, traders, retailers and

consumers

Postharvest losses

These losses may be caused by complete

wastage of the product or by lower prices due to

a reduction in quality. The cost of these losses is

also important as the value of the product

increases several fold from the farm gate to the

final consumer, so in dollar terms postharvest

losses are even more significant.

There are generally three main

causes of postharvest losses.

1. Disease caused by fungi and/or bacteria

2. Physical injuries due to insects, mechanical

force, chemicals, heat or freezing

3. Non-disease disorders resulting from storage

conditions that upset normal metabolism when

the product is rejected further down the marketing

chain .

Other factors of postharvest losses

In addition to genetic traits, environmental factors

such as soil type, temperature, wind during fruit

set, frost, and rainy weather at harvest can have

adverse effects on storage life, suitability for

shipping, and quality. Cultural practices may have

dramatic impacts on postharvest quality. Good

Agricultural Practices during harvest operations

and any subsequent postharvest handling,

minimal or fresh-cut processing, and distribution

to consumers must be developed.

QUARANTINE SERVICES

The primary role of the Quarantine Division is to

reduce postharvest losses in an effort to ensure

that all practices from production to export are

strictly adhered to. Any farmer or exporter found

violating the system is automatically suspended

for non compliance. Farms are therefore closely

monitored by the Quarantine and the Extension

Departments.

Losses in Storage

The improper handling, packaging, storage and

ransportation may result in decay and production

of microorganisms, which become activated

because of the changing physiological state of

the fruits and vegetables. Fruit, due to their low

pH, higher moisture content and nutrient

omposition are very susceptible to attack by

pathogenic fungi, which in addition to causing rots

may also make them unfit for consumption by

producing mycotoxins

Primary factors responsible for post-harvest produce

losses are: poor pre-harvest measures-- adoption of

poor production techniques (varieties with low shelf

life, imbalance use of nutrients, insect pest and

disease infestation and abiotic stresses; low tech

harvesting procedures-- non-application of

pre-harvest recommended treatments/practices,

harvesting at improper stage and improper care at

harvest; and post-harvest problems-- non-removal of

field heat, dumping produce, moisture condensation

causing pathogen infestation, packaging in bulck with

out sorting and grading of produce, improper

transportation and storage, and distant and time

consuming market distribution

. In order to preserve the produce quality different post-harvest

techniques are recommended for variety of produce. These techniques include; hydrocooling, refrigeration & freezing, modified atmosphere (MA) packaging, MA storage, control atmosphere storage, skin coating, hypobaric or low pressure storage, irradiation, dehydration, canning, high pressure processing and pulsed electric fields and pulsed light applications. In order to promote horticultural industry in Pakistan, standardization of pre-harvest and post-harvest management technologies minimizing postharvest losses and to enhance foreign exchange earning to the maximum extent are therefore essentially required for necessary adoption. At present various R&D institutions are working on different aspects of postharvest management of vegetables and fruits.

ADVANCES IN POSTHARVEST

TECHNOLOGY AND RESEARCH Selection of varieties for better shelf life

Vegetable varieties: Riogrande, Roma AVRDC Cv. (tomato), NARC - 91 (onion), Medium Long Green (chillies), Local Selections (cucumber) and VIP (pea) have shown better transportation quality and longer shelf life. In fruits; varieties: Begum Jangi (date palm), Cardinal, Flame Seedless (grapes), Local Selections (fig), Sultan (pomegranate) and ARS (N) Mingora No. 7, No. 8 & No. 9 (peach) were found high yielding with longer post-harvest life.

Influence of rootstocks on postharvest quality of some apples

Studies carried out at Deciduous Fruit Development Centre, Sariab, Quetta revealed that on rootstock MM 106, apple cultivars (Red Delicious, Golden Delicious, Star King Delicious and Spartan) showed better performance than on M-9 rootstock for fruit texture and soluble solids. On the basis of organolepticevaluation or consumers' acceptability' MM-106 showed partially better performance than M-9. For skin colour of fruit, rootstock M-9 showed better results over MM-106. However, rootstock MM-106 should better performance in terms of fruits texture, total soluble solid contents and consumers' acceptability over M-9 rootstock.

Pre-harvest application of fungicides

Pre-harvest application of Benlate 50

WP minimized mold growth and increased shelf

life of citrus (Kinnow Mandrin) at ambient storage

temperature.

Pre-harvest application of growth hormone

GA3 when applied @ 20 ppm on grape Cv.

"Kishmish" not only increased the berry size, yield,

protein, reducing & non-reducing sugars, pectin and

ascorbic acid but also, the mineral contents of berries

(sodium, calcium magnesium and iron contents) were

increased hence improved the quality of fruits and

also its postharvest longevity.

Postharvest application of calcium chloride

Freshly harvested tomato fruits of

variety" Nagina" when dipped in 4% CaCl2

solution and kept at 15oC maintained marketable

quality upto 16 days

Studies on degreening of citrus and mango

Studies on degreening of citrus and mango showed that citrus variety "Salustiana" stored at 30oC and 85-90% RH (controlled atmosphere) developed uniform colour after 24 hours, whereas in case of variety "Honey Mandrine" there was a slight colour development even after 36 hours. In case of mango variety "Chaunsa" stored at 17oC and 80-85% RH after chilling resulted uniform colour development and produced natural flesh taste.

Studies on wax coating materials

Wax coating studies are being carried out to make the produce more attractive with better shelf life. Carnauba based surface wax increased shelf life of Kinnow 3-4 weeks by delaying senescence. Edible film coatings with gelatin (4%), corn starch (3%), HPMC (3%) and stearic acid (1.5 to 3%) composition enhanced storage life of carrots variety, "T-29" upto45 days with minimum (10-15%) post-harvest water loss

Studies on potato storage

Autumn potato crop is the main crop grown in the plains of Punjab. The crop is harvested during the month of January. The produce is kept in the field until the end of February because of low temperature. Thereafter, potatoes are mostly stored in the field in ordinary storage structures, where weight loss, rotting and sprouting of tubers deteriorate the quality of produce. In cold storage the produce is held at 4-5oC. At this temperature starch is converted to sugar and therefore potatoes become sweet. Also, because of high charges of electricity this costs much higher as compared to ordinary storage conditions or storage of potatoes at relatively higher temperature. Studies associated with these problems reveal that:

1. Improved low cost on-farm storage structure (where hot air is replaced by cool air during night using electric fan) the inside temperature was observed 3-4oC low and the stored potatoes retained marketable quality upto 90 days.

2. The sprout suppressant, "Camptothecin" when applied (sprayed) @ 0.5 mM inhibited sprouting of tubers upto 45 days at 39oC, whereas in untreated control sprouting started after 30 days at 39oC.

3. The sprout suppressants CIPC @ 1500 ppm and 2000 ppm, IPC @ 1500 IPM and 2000 ppmand DECCO - 276E (combination of CIPC and IPC) @ 4.4 ml/100 ml water spray checked weight loss, sprouting and sweetening when potatoes were held at 5oC and 9oC storage temperatures and 90% RH until 105 days.

4. Quality of potato tubers when held at 5oC or 9oC and 90% RH was retained until 60 days as the weight loss, rotting, sprouting and sweetening were checked.

Studies on tomato fruit storage

In case of tomato, variety "Nagina" when

dipped in 4% CaCl2 solution and kept at 15oC

maintained marketable quality upto 16 days.

Quality preservation of apricots

Apricots when dipped @ 3% solution of

potassium meta bisulphite for 3 hours and then

dried proved to be successful.

Actors Problems (in order of

importance

Desirable

solutions

Producers

1- Lack of irrigation

infrastructures

2- Poor access to markets/high

competition of imported products

3- Lack/insufficient access to

credit

4- Poor access to treatment

chemicals and seeds

5- Insects and nematodes

6- Lack of skilled workers

(training)

7- Transport and storage

1- Implementation

of performed

infrastructures for

irrigation

2- Credit

3- Proximity and

availability of

treatment

chemicals and

seeds

4- Well trained

workers

Traders

1- Poor access to credit

2- Poor access to markets

3- Lack of traders association

4- Transport and storage

5- Insects and fungi

1- Access to credit

2- Training for

producers on use

of inputs (fertilizers

and pesticides)

Focus group

Suggestions

Improved access to high quality seeds (variety shelf life) and other inputs

Training of producers on appropriate use of fertilizers and pesticides, the appropriate marketing and production planning methods

Improved transport practices, packaging technologies (eg: using folding plastic boxes), improved storage infrastructures

Improved access to credit and improved providing policy makers subsidies to producers

Training traders on effective and efficient transport or storage practices

Monitoring of mycotoxins and pesticides residues