Fresh Tomatoes

Tomatoes are not all picked at the same stage, and the stage chosen defines the commercial lot. Fruit destined for distant markets is commonly harvested mature-green — physiologically mature but not yet coloured — because firm green fruit tolerates handling and transport far better than soft coloured fruit. Fruit for nearer markets may be picked at breaker stage, when colour first appears, or held on the plant to colour more fully.

The distinction that matters is between maturity and ripeness. A mature-green tomato has completed enough development to ripen properly once detached; an immature-green tomato has not, and will never develop acceptable colour, flavour, or texture no matter how it is handled afterwards. Picking immature fruit is therefore an irreversible quality loss, and judging maturity is a core skill in the harvest of this commodity.

The tomato is a climacteric fruit: after harvest it passes through a rise in respiration and produces ethylene, which drives the colour, softening, and flavour changes of ripening. This is why mature-green tomatoes can be shipped firm and ripened on arrival, and why ethylene is managed deliberately in the trade — applied in ripening rooms to bring a lot to a uniform stage, and excluded where fruit must be held back.

Ethylene control cuts both ways. The same gas that ripens tomatoes on purpose will over-ripen them by accident if a lot is stored near an ethylene source, and tomatoes themselves emit ethylene that can damage sensitive commodities stored alongside them. Mixed-load compatibility is therefore a real commercial constraint, not a theoretical one.

Most vegetables keep best as close to freezing as they can safely be held. Tomatoes do not. As a warm-season fruit the tomato is chilling-sensitive: held below the temperature it tolerates, it suffers chilling injury — a physiological disorder that shows as failure to ripen or colour evenly, pitting, water-soaked patches, loss of flavour, and increased decay once the fruit is returned to warmer conditions.

The damage is often invisible at the point where it happens and only appears further down the chain, which makes it a recurring source of commercial dispute: a lot can leave storage looking sound and arrive unsaleable. Chilling injury is also cumulative, so repeated brief exposures matter. The practical consequence is that tomatoes need their own temperature regime rather than the default vegetable setting, and that regime differs with the maturity stage of the fruit.

Fresh tomatoes are graded on attributes that a buyer can verify on arrival: maturity and colour stage, firmness, size and uniformity, shape, and freedom from defects. Colour is often assessed against published stage charts so that a lot can be described consistently between seller and buyer. Grading is done by hand, by machine, or by both, and lots are commonly sized as well as graded.

• Mechanical damage — bruising, compression, and abrasion from harvest and packing
• Cracking and splitting — radial or concentric, often set before harvest
• Chilling injury — uneven ripening, pitting, and flavour loss from over-cold holding
• Decay — soft rots and moulds, typically entering through wounds
• Sunscald and blotchy or uneven colour
• Overripe and soft fruit arriving past its useful stage

Because the fruit is soft-skinned and continues to change after picking, tomato quality is a moving target rather than a fixed measurement: a lot is described at a moment in its life, and the grade recorded at packing is not necessarily the grade on arrival. Grade standards are jurisdictional and are revised, so the edition in force governs.

Most fresh-market tomatoes are eaten as fresh fruit. A separate and much larger stream of tomatoes is grown, harvested, and delivered specifically for processing into concentrates — paste above all — and those fruit are handled as a bulk raw material rather than as fresh-market produce. Paste is the main intended output of that processing; the skins and seeds left after extraction leave the plant as pomace, a residual stream with feed value.

• Food — sold and consumed as fresh fruit, the dominant use of this commodity
• Processing — concentration into paste and other tomato products
• Feed — pomace and out-grade fruit used in animal rations