Researchers improve storing technique for tomato

Batac CITY—Tomato farmers can now prolong the shelf life of their produce if they harvest them at mature green stage, mix them with rice straws, and store them in plastic sacks or paper boxes. This technique was proven to be very profitable if they want to sell the fruits in off-season months when there is a limited supply of tomato.

In a test conducted by researchers Maura Luisa S. Gabriel, Marissa I. Atis, Aleta E. Dumaoal and Zenaida H. Esteban of the Mariano Marcos State University (MMSU) in this town, tomatoes stored using the improved technique will last for more than two months with extremely low percentage of rotten fruits. The containers, however, should be placed on an elevated floor with good ventilation, and with ambient temperature which ranges from 26 to 34 degrees Celsius.

Places with ambient temperatures are those inside an ordinary store house with nipa or cogon grass roofings which are built under shady areas.

The researchers said this improved storing technique for tomato could give farmers a substantial return of investment (ROI) of 129 percent per 10 kilos of tomato, higher by almost 50 percent than the traditional methods being practiced by tomato growers and traders who store their fruits in bamboo crates, plastic sacks, and paper boxes without rice straws.

This is so, because the price of tomato in Ilocos Norte falls to a farmgate price of P15 per kilo during March to April when harvest floods the local markets. Some farmers who are not practicing the storage technique would not even want to harvest their ripe tomato because they would spend more in the wages of the harvesters than the price of their produce.

But with this improved technique, farmers could prolong the shelf life of their tomatoes and could sell them during off-season months when the farmgate price is pegged at a farmgate price of 60 to P80 per kilo.

The experiment

The researchers tested the other conventional materials and method of storing tomato by farmers at Brgy. Quiling Sur, Batac, Ilocos Norte who were either tomato growers or fruits traders. The results were compared with the new technique that they are recommending.

The farmers were using ordinary bamboo crates and baskets, paper boxes, plastic sando bags, and plastic sacks as packaging materials for tomato. But the difference with the improved packaging materials is that they used old newspapers as linings and coverings of the packaging containers.

This traditional method, according to the researchers, have contributed the increased rotting percentage of the harvest, thus, giving them heavy losses especially if the fruits are not sold immediately—at least less than one month after harvest.

Farmers who stored their tomatoes in the traditional way found out that most of the fruits rot after two months, which disastrously lowered the volume of marketable fruits.  Fruits that rot earlier than expected affected those that were ripening, while many also shriveled because of moisture loss. However, the shriveled fruits were still sold in much lower price.

The highest percentage of rotten fruits, which was about 61.33 percent, was observed among the fruits that were stored in ordinary crates alone, while the lowest, which was 3.75 percent, was observed in paper boxes with rice straws. 

“That’s why we advise farmers to mix the tomatoes with rice straws before putting them in the recommended packaging containers and provide the fruits with proper aeration and minimum physical contact,” the researchers said.

The researchers also found that hanging the fruits, whether they are packed in plastic sacks or net bags with newspapers inside, will cause 10.67 percent and 16.26 percent damages, respectively.

Results further showed that the percentage of shriveled fruits was high in fruits packed in plastic sacks and hanged, which was about 17.33 percent. This was comparable with those in hanged net bags with newspapers (11.33 percent).

The least percentage of shriveled fruits was observed among those mixed with sawdust and stored in ordinary crates and paper boxes, which was about 1.33 percent and 2.29 percent, respectively. Most of the fruits there were already rotten; hence, the moisture in the sawdust from the rotten fruits prevented high transpiration from the other fruits.

Results also showed that weight loss in fruits mixed with rice straws and packed in cartons was lowest (about 30.04 percent) after two months. This was comparable with those in hanged plastic sacks which were about 32.49 percent, followed by those lined with newspapers and hanged in net bags (42.36 percent) and those in plastic sacks (44.61 percent).

The researchers said that the volume of marketable fruits was highest in fruits mixed with rice straws and stored in paper boxes, which was 69.46 percent, and those mixed with the same material and stored in plastic sacks (67.41 percent).

The highest percentage of weight loss was also observed in fruits mixed with sawdust and stored in paper boxes (78.37 percent) and those mixed with the same material and stored in ordinary crates (77.49 percent) followed by those lined with newspapers in bamboo baskets (60.50 percent). This was comparable with those stored in paper boxes, which was about 57.49 percent. 

Meanwhile, the lowest volume of marketable fruits was obtained from those stored in ordinary crates alone (22.51 percent) and in paper boxes with sawdust (21.63 percent).

Storing tomatoes

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In Ilocos Norte and some parts of the Ilocos region, storing mature green tomatoes has become a perennial practice by farmers and traders who believe that they could derive substantial profits, especially if the fruits are still fresh after several months of keeping them. However, with their own traditional techniques, farmers usually get low profits.  

Most farmers even store their tomatoes in plastic sacks and bamboo crates that were used to carry grass for their confined or tethered livestock, thus, increasing the risk that the harvest might be contaminated with pests, fungi, and other harmful organisms that were left inside the crates. Then, the packed fruits are either hanged, laid horizontal or in vertical position, and are placed in open space inside their makeshift warehouses with roofs made of galvanized iron.

To avoid this, farmers should clean the plastic sacks and paper boxes before using them, and check whether the fruits are free from damages caused by pests and diseases.

Prior to storing, rice straws must be collected from threshed panicles in rice paddies. These should be mixed with the harvested mature green fruits at a thickness of about 2 – 3 centimeters (cm).