July 31, 2006	Monday	Rajab 4, 1427

CHILLI, an important crop of Pakistan, is cultivated on 64.53 thousand hectares with 122.89 thousand tons of production.

It is a rich source of vitamin A, C and E with medicinal value in assisting digestion, preventing heart disease and dilating blood vessels.

It is a major Kharif crop of Sindh grown on 0.5535 million hectares. Its production fulfils 88 per cent of the country’s requirement. Chilli not only meets domestic consumption but also helps in earning foreign exchange.

Aflatoxin is a chemical produced in chillies due to fungal causal organisms i.e., aspergillus flavus and apergillus parasiticus. It comes in chillies during picking, drying, handling, packing, and transportation because of the metabolic activity of fungus, physical rupturing and insect damage.

Aflatoxin is one of the sources of primary liver cancer (PLC) in human and animals.

According to the World Trade Organization (WTO), the international aflatoxin permissible level is less than five parts per billion (ppb).

The domestic produce could not meet the international aflatoxin permissible level due to poor quality resulting from poor drying, unhygienic practices, improper storage, overuse of pesticides, lack of government support and competition with other exporters like India, Mexico, Thailand.

Less acreage, last year, could not earn reasonable rates for growers. Being a major cash crop of Sindh and foreign exchange earning, it is important to prevent the produce from aflatoxin by adopting latest post harvest techniques.

The potential for chillies can be optimized through increasing per acre yield, improving the quality, minimizing post harvest losses, introducing new drying technology and finding new markets.

The post harvest management of chillies comprises picking, handling, drying and grading, packing, storage and transportation. An aflatxin free chilli is only possible by proper picking, good handling practices, necessary improvement of traditional sun drying practices, introduction of commercial scale mechanical dryers, isolation of old and new chillies, proper grading and storage.

Quality of fruits is a combination of flavour, texture, appearance and food value which gives pleasure or satisfaction to consumers. Maturity is the state of ripeness and determined by firmness, coloration and tasting. The picking should be done at the time of maturity that is the point of highest quality commensurate with high yields.

Delayed picking at that point may reduce the gross and net returns by virtue of non-transferring of dry matter toward commencing matured fruits and deterioration of the quality by wrinkles and colour fading.

Chili crop does not mature at one time and ripe crops should be harvested at frequent intervals. The most important factors affecting aflatoxin formation are moisture, temperature and insect and physical damage.

During picking, the chillies must avoid the direct contact with dew and rain. Ill handling is also one of the major causes of aflatoxin contamination to chillies which can be ameliorated by orientation and creating the awareness among growers to produce the internationally acclaimed product. Careful handling from picking to transportation results in minimum injured, broken or ruptured produce.

Quality regarding aflatoxin also depends on drying. Fresh picked chillies have unsafe moisture content which results in heating of the fruit and rapid deterioration. To avoid microbial activity and aflatoxin production, the moisture content in dried pods should not exceed 10 per cent by weight. There are two methods of drying i.e., sun drying (natural drying) and artificial drying (mechanical drying).

During the dry season, sun drying is usually simplest and cheapest method to dry chillies. In this method the produce is spread on an open floor or roof of the building and exposed to sun for 10–15 days. However, some problems are associated with this method. Dust or dirt is blown onto the crop which contaminates and unexpected rainstorms can re-wet the produce, which activates microbial activity and ultimately aflatoxin contamination.

Sun drying also results in poor colour of the pods due to the bleaching effect of sunrays. These problems can be avoided by modifying the method of drying. In simple sun drying, leveled and compact yards are made and these yards are plastered with clay soil to avoid the dust or dirt contamination.

Mats and sheets of different materials can also be used to avoid the contamination of dust or dirt. From the fifth day onwards, the produce is inverted on alternate days so that pods in the lower layers are brought up to ensure quick and uniform drying.

While drying, the produce is covered with polythene sheets during night to avoid dew deposition and colour fading. Solar dryer and tray dryer can also be used, which not only saves the time of drying operation but also impart deep red colour and glossy texture to the produce. These dryers also avoid the re-wetting of produce due to unexpected rainstorms.

During the wet season or times of humidity, which often coincides, with the harvest of the spices, a solar dryer or sun drying can not be used effectively. An artificial dryer/mechanical dryer that uses a cheap energy source is necessary. In this type of dryers, chilli pods are placed on perforated trays and hot air is forced through chillies with an approximate rate of 75-85 m3 of air per minute per m3 of chillies. This may be wood or husk burning dryer or a combined wood burning and solar dryer.

Grading is a process in which undesirable small sized, damaged, aflatoxin contaminated and discoloured chillies are separated from healthy, high quality and brighter red coloured chillies. Grading is necessary to get the maximum value of the produce. Old and new chilli crop should be separated during grading process.

Graded produce is packed in gunny bags. Properly packed chillies are stored in damp free well-aerated storerooms at room temperature (25–28 oC).

Moisture content and relative humidity should not be more than 14 and 60 per cent, respectively in the stored area. Chilli produce should be protected from pests like insects, moulds, rodents and birds. No insecticides should, under any circumstances, be used directly on chilli produce. Stored material should be subjected to periodic fumigation.