Breakthrough: Tomatoes that can last for six months without refrigeration

BATAC, Ilocos Norte – April is a month when the price of tomato is very cheap. Harvests flood the local market and the fruit is sold at a low P5 per kilo.

Farmers can earn a lot more from their tomatoes if they can store them for up to six months and sell the fruits at a time wen the supply is scarce.

The problem is, tomato easily rots. How can farmers store their harvest up to six months?

"They can," said researchers Maura Luisa S. Gabriel, Zenaida R. Pambid, and Tessie U. Tagala of the Mariano Marcos State University (MMSU) in Batac, Ilocos Norte.

Gabriel, who led the team of researchers who conducted the study, said if farmers harvest the mature green fruits and hang them, the harvest would last up to six months. The method does not need chemicals, preservatives, equipment and electricity, they said.

Tomatoes stored by hanging are profitable after 16 to 20 weeks, but Gabriel said higher net income can be realized if the fruits are sold one to two months after harvest.

To accomplish this the researchers said farmers should plant the Apollo variety, because this is the only tomato which can be stored for six months by hanging.

The optimum storage period of other varieties such as the native using the hanging method is 11 weeks with 50 percent rotting. Using the modified atmosphere packaging (MAP) method, tomatoes last up to four-and-a-half months. MAP is a storage method commonly used by farmers and fruit traders.

In MAP, fruits and vegetables are sealed with plastic film so that their respiration is reduced due to decreased oxygen and increased carbon dioxide concentrations inside the pouches.

In hanging, the Apollo variety can last for six months with only 52 percent rotting. When hanged, mature green fruits of Apollo were observed to have lower moisture loss and rotting than those stored in MAP.

The plastic film allows the entrance of the minimum amount of oxygen required by the products to continue normal aerobic respiration.

The best concentration of oxygen and carbon dioxide in keeping freshness of fruits in MAP varies according to the kind of products stored, their temperature, and some other factors.

Lanzones stored in MAP using polyethylene bags with 16 diffusion holes (DH) each had lesser weight loss than those stored in other methods. However, the fruits will become brownish after a few days.

A 22-kilogram crate of tomatoes stored in MAP with 24 DH was also found effective, but the fruits will not last longer than two months, because of the high degree of rotting.

MAP is suitable for lanzones, tomato, okra, leafy vegetables, and banana for just a few weeks only. Banana can be packed in fingers, hands, and clusters in 1.5 mm thick polyethylene bag in cartons. Aside from being very laborious, MAP entails a lot of money since farmers need plastic bags for storage.

"In hanging, the firmness of tomatoes is maintained and they remain fresh-looking even beyond the full ripe stage," the researchers said.

In storing their harvest, farmers should pick the green mature fruits and leave the short stem stub. The fruits should be free from insect and disease damages.

Tie the fruits individually with a 50-cm long strip of plastic twines. Hang the fruits like bunches of grape berries, or lanzones fruits about 1.5 to 2 meters above the ground. Or farmers can just uproot the whole plant and hang it upside down.

Store the fruits at room temperature where there is enough ventilation. Inspect the tomatoes periodically and remove the decayed ones.

Stored fruits with stems remain firm and fresh looking for 104 days, while those without stems turn very soft after 36 to 49 days.