HARVESTING

Time of harvest

Picking of fruits from the plants depends mainly on the purpose for which they are grown and the distances through which they are to be transported. The different stages at which the tomato is harvested are immature green, mature green, turning pink, half ripe, red ripe and over ripe. Mature green fruits are those which have not begun to turn pink. Turning pink means shows some pink colour at the blossom end. Half ripe fruits show pink colour over most or the entire surface. Ripe or red ripe fruits are those which have developed full colour and are firm. Generally, firm mature green fruits are best suited for shipping or distant marketing. For fresh consumption, tomatoes are harvested at the turning pink or half ripe stage. For seed production, red ripe tomatoes are ideal. Fruits for canning or juice extraction are harvested when they reach the red ripe stage and processed soon thereafter.

Tomatoes are harvested twice a week when the plants are about three months old. Fruiting may continue for a period of 1–2 months based on the cultivar, soil and climatic conditions. Tomatoes ripen on the plant itself; however, ripening may take place after harvesting as well. For artificial ripening, the fruits are harvested at the mature green stage or at the turning pink stage and kept under room temperature (15–25 oC). Harvested fruits produce adequate quantities of ethylene, the release of which aids in the ripening process. Fruits which ripen on the plant are superior in vitamin C content when compared with artificially ripened ones.

Post harvest Techniques

Grading

Damaged, rotten and cracked fruit are removed. Healthy, attractive, clean and bright fruits are preferred. The grades are based on the appearance and quality of the fruits and not specifically on their size. Grading based on size is done mostly by retailers for the local market: the fruits are graded as small (<100 gm), medium (100–255 gm) and large (> 255 gm). Urban markets have differential pricing based on size grades. The Bureau of Indian Standards (BIS) has specified four tomato grades, viz., 'super A,' 'super,' 'fancy' and 'commercial.'

Packing

Wooden boxes, crates, polythene bags or baskets can be used for packing tomatoes. For local markets, the fruits are packed in bamboo baskets or plastic crates. Plastic crates are more convenient for handling since they can be stacked one above the other. The contoured rim keeps the product safe and allows sufficient air circulation. The packing should be rigid enough to protect the fruits from being crushed. For export, the fruits are packed in cardboard boxes of 15 kg capacity. Size graded tomatoes are packed in layers in such boxes in order to make the best use of the box.

Storage

Tomato producers in India lose about 20–30 percent of their crop in post harvest spoilage. The main objective of storage is to extend the shelf life of the produce by controlling the rate of ripening. High temperature, humidity and oxygen reduce the shelf life of the fruit and bring about spoilage. Temperature between 12–15 oC is ideal for storage. The ideal storage temperatures differ depending on the maturity of the fruit. A temperature of 13 °C and 90–95% relative humidity is recommended to slow down ripening. At this temperature, most varieties keep in good condition for about 2–3 weeks and the colour change is very gradual. Unripe tomatoes can be stored for 4 weeks at a temperature of 8–10 °C and 85–90% relative humidity. Fully ripe fruits can be stored for about a week at 7 °C and 90% relative humidity. Below this temperature, the fruits show symptoms of cold injury. Atmospheric storage conditions with 5% carbon dioxide and 2.5% oxygen are best. The recommended relative humidity is 85–90%.

Traditional storage techniques

Tomatoes can be stored in baskets in which the fruits are piled with alternate layers of charcoal and left undisturbed for six months. They will be fully ripe but still fit to eat. Plants with unripe tomatoes can be hung in a shady place upside down and they will keep fresh thus for up to three months. The compound responsible for ripening is supposed to move more slowly when tomatoes are inverted. Some farmers preserve tomatoes by keeping them in a cool sand bed. They can thus delay selling the tomatoes by 30–45 days and get a better price for them.

Usage

Fresh fruits are consumed raw as salads or after cooking whereas unripe fruits are cooked before consumption. Fully ripe fruits are also used for canning in large quantities. The fruits are also consumed in the form of juice. The other products of commercial value made out of tomato are puree, paste, ketchup, sauce and soup.

Other uses

Tomatoes can also be used to boost the growth of paddy seedlings. The tomatoes are first dried in sunlight; the seeds are then extracted and powdered. Fifty-five grams of the seed powder are mixed with a sticker solution and sprayed over the paddy seedlings in the nursery 14 and 21 days after sowing to boost seedling growth. For spraying one hectare of paddy, 500 gm of tomato powder mixed with 100 ml of sticker solution is sprayed 14 and 28 days after transplantation.

Transport

The fruits are highly perishable in nature and hence need to be transported at the earliest. Tomatoes are transported by road through tractors, trucks and also by rail and air to distant markets. Village produce is transported to the nearby towns and city markets only by road. Maintenance of a cold chain is essential during transport of export produce.

Updated on : Dec 2014