Pitting

A record that reads "pitting" has documented that depressions were seen. It has not identified a disorder, established a mechanism, or located a failure in the chain — though the word is confident enough that it is routinely treated as though it had. The underlying event is the same in every case: cells below the skin lose integrity, the tissue beneath collapses, and the surface sinks. What killed those cells is the entire question, and the pit is silent on it.

Chilling injury

In chilling-sensitive commodities, holding below the tolerated temperature but above freezing disorders membranes and metabolism, and localised cell collapse expresses as surface pitting. This is much the most common cause in tropical and subtropical produce, and it usually appears only after return to warm conditions.

Pathogens

Several rots begin as small, firm, sunken lesions before any sporulation or soft breakdown is visible, so early infection presents as pitting and is regularly recorded as a physiological disorder.

Physical and handling damage

Impact, abrasion, compression in a stack, and pressure against packaging all collapse cells locally beneath skin that remains unbroken, giving sunken marks that darken as the damaged tissue browns.

Controlled-atmosphere injury

An atmosphere carrying too much carbon dioxide or too little oxygen for the commodity injures tissue, and surface pitting is among the presentations that follow.

In cucumber, sweet pepper, citrus, avocado, and mango, chilling injury is the reason pitting is usually seen. These are commodities of tropical and subtropical origin that are progressively disordered by temperatures well above their freezing point, and localised cell collapse showing as surface pitting is one of the ways that disorder expresses itself. Anyone finding pitting in these commodities after cold holding is right to look at temperature history first — that is where the answer most often is.

But "most often" is a statement about a population of lots, and it does not resolve an individual one. The commonest cause is not the only cause, and reasoning from prevalence to a particular consignment is how early rots get written off as cold damage and how compression damage in a badly stacked pallet gets blamed on a cold chain that was running correctly. The overlap between this entry and chilling injury reflects a real relationship in the world; it does not convert a symptom into evidence. The chilling-injury entry sets out the mechanism, the delayed expression on warming, and the temperature records needed to establish it — that is where a suspected chilling cause is properly pursued.

Although a single pit is uninformative, the distribution of pitting across a unit and across a lot carries hints worth following. These are hypotheses about where to look next, not tests, and every one of them has a common exception.

The recurring lesson is that the information which separates these causes is not in the fruit surface. It is in the temperature record, the atmosphere record, the handling history, and where necessary a laboratory that can say whether an organism is present. A pitting observation is the start of that enquiry, and treating it as the end is the error the name encourages.

Because pitting has several causes, no single control addresses it, and pursuing the wrong one is a real cost — a chain that responds to chilling-caused pitting by improving packaging, or to compression-caused pitting by raising store temperature, has spent effort and fixed nothing. The measures below act on the different causes, and which of them is relevant depends on what the records show.

• Hold chilling-sensitive commodities within their own temperature tolerance through every link of the chain, since this addresses much the most common cause in tropical and subtropical produce.
• Keep temperature records continuous enough that a symptom seen after warming can be traced to the leg that caused it, since chilling expression is delayed.
• Reduce mechanical damage at transfers and in stacking, and use packaging that limits compression and contact pressure, where handling is implicated.
• Specify and monitor controlled atmospheres against sourced guidance for the commodity, since an unsuitable atmosphere injures tissue and pits it.
• Handle a suspected pathogen cause as a pathology question — early rot lesions present as pitting and require laboratory confirmation, not visual assessment.
• Segregate commodities with incompatible temperature requirements rather than running one store at a compromise setting that pits the sensitive ones.