Ripeness at harvest. The ripening stages in the tomato fruit are described as immature, mature green, breaker, pink, and red. Mature greens have a white to yellow 'star' on the blossom end, but the only definitive test of maturity is to cut the to mato in half. If the seeds are cut by the knife, the fruit is still immature. Needless to say, this test is not very useful to pickers. In practice fruit are picked by size and location on the plant as described below. The breaker stage occurs within 24 hours of the mature green stage and is easily distinguished because the blossom end is pink. 'Breakers' ripen naturally without gassing and are labelled in supermarkets as 'vine-ripe'.

Fresh market. Tomatoes harvested at the mature green stage make up the bulk of the commercial fresh market tomato crop because they tolerate rough handling better than the riper stages and hold the longest in storage, shipping, and on the supermarket shelf. In the industry, this is referred to as having a low shrinkage rate. North Carolina recommendations are to harvest green matures when about 10 percent of the fruit on the first hand is at the breaker stage of maturity. All fruit on the first two fruit hands are generally removed at this harvest. The second harvest normally takes place from 10 to 14 days after the first. Fruit 2¸ inches in diameter or larger are removed from the middle of the plant. At the third harvest, 10 to 14 days later , fruit are removed from the upper portion of the plant. Vines and fruit should be completely dry when mature green fruit are harvested. Otherwise, fruit shoulders may develop sunken, blackened areas during ripening. Vine-ripes must be hand harvested t horoughly and as frequently as every other day. Fruit which turn pink or red-ripe on the vine are unmarketable through commercial channels.

The flavor of supermarket tomatoes is frequently criticized by consumers. Under controlled experimental conditions, properly handled mature green tomatoes develop flavor to the same extent as fruit left on the vine another 24 hours, until color appears, the 'breaker' stage. To the extent immature greens are picked, however, eating quality is reduced even though these tomatoes can be gassed to redness with ethylene. The problem is determining when the tomato reaches the mature green stage in the field.

Recently more vine-ripes have been appearing in stores because of consumer demand for better-tasting tomatoes. A number of companies have also introduced 'long-shelf life' tomatoes that reportedly stay firm for several weeks, even when picked at the brea ker stage. Current long shelf-life tomatoes were bred by conventional means but a genetically engineered slow-ripening tomato, FlavrSavr¨, is scheduled for 1995 release by Calgene. It is not clear what the market impact of these long-shelf life tomatoes will be. They can be left on the plant longer to develop better flavor, but they are being adopted by the industry because they can also sit longer on grocers' shelves without breaking down. Will the consumer be eating a tastier tomato when more of the se long shelf-life tomatoes start to appear at the supermarket? There may well be some improvement, but the excellent flavor and texture which consumers associate with the home-grown 'beefsteak' type tomatoes is a varietal characteristic as well as the result of turning red-ripe on the vine. Few of the cultivars bred to withstand the rigors of long-distance shipping and bulk handling have these characteristics whether picked mature green or red-ripe.

Processing. Tomatoes to be canned or used in processing are harvested red-ripe. They retain quality on the vine for several days after ripening and harvest is timed to maximize red-ripes. The fruit are sturdy enough to withstand mechanical harve st even when red-ripe and 80 to 90 percent of all processing tomatoes are mechanically harvested. One mechanical harvester can cover 5 to 8 acres in 8 hours.

Handling. After harvest, fresh market tomatoes are usually dropped into a water tank to clean the fruit. Improper dump tank procedures can also spread disease, however, increasing storage losses. Disease spread can be minimized by:

1. Not allowing fruit to submerge deeply or to float more than one layer deep in the tank. Pressure from deeper submersion forces pathogen-containing water through the stem scar into the fruit.
2. Removing fruit after two minutes.
3. Chlorinating the water and maintaining the free chlorine level at 300 ppm.
4. Warming tank temperature to 10 degrees F above fruit temperature. Cool water constricts the fruit, pulling in pathogens.

   Postharvest

   Commercial crops of fresh market tomatoes picked at the mature green stage are ripened artificially with ethylene gas in special rooms. Relative humidity in the gassing rooms is 90 to 95 percent but the ripening temperatures used depend on how soon the f ruit is needed. Mature green tomatoes should start to develop red color in 5 to 7 days at 65 to 68 degrees F. The speed of the process can be changed by raising or lowering the temperature or slowed down by lowering temperatures. Tomatoes will not ripen at temperatures above 85 degrees F or below 50 degrees F. Extended exposure of green tomatoes to temperatures of 40 degrees F or lower causes rotting of fruit before they ripen. In a 42 degrees F refrigerator, enzymes necessary for ripening are deactiva ted and the tomato won't ripen even after you take it out. Thus, tomatoes should not be kept in the refrigerator unless they are already fully ripe. Unripe fruit should be taken off the vine in the fall before temperatures get too low. Fruit can be kept up to 57 days in controlled environment storage at 54 degrees F, 5 percent CO2 and 5 percent O2 but this is rarely done in practice because fresh tomatoes are always available somewhere.