With stone fruit season nearing, a defect you must keep an eye out for is internal discoloration or internal breakdown occuring in nectarines.
Most nectarines can be stored for a week to 10 days at 40° F with little or no deterioration. They can be stored for up to 3 weeks at 31 to 32° F without serious loss of quality. If stored for longer periods, they are subject to internal breakdown, loss of flavor, discoloration of the flesh, surface pitting and decay. Following longer storage periods, the fruit may appear normal, but often develops serious internal breakdown when transferred to ripening temperatures. The first evidence of breakdown is a reddish brown discoloration and a granular texture of the flesh. The discoloration is usually darker near the pit. Later the flesh becomes a darker brown, often with gray-brown water soaked areas extending from around the pit into the flesh. The graininess increases and the affected flesh has a woody or mealy texture, is off-flavored and lacks juiciness. Even in such advanced stages of breakdown, the fruits usually have a normal external appearance.
The nectarine pictured above was imported for Chile. There were no external symptoms at all, the nectarine was still considered as being firm, and the nectarine was cut randomly. Always cut crosswise, as pictured to look for evidence of internal defects. This nectarine had an off flavor, but was not mealy in texture. At this stage I would describe the defect as “Internal discoloration” and like internal breakdown, when scored it is always scored against the 6% tolerance for serious damage, a condition defect.
The USDA does have a sampling plan if you encounter internal defects in nectarines. It reads as follows:
During examination for external defects it may be difficult for inspectors to detect the presence of internal defects. Some fruit must be cut from every sample. The number of specimens cut is discretionary and based on such factors as varietal characteristics (some varieties are more susceptible to internal discoloration than others), growing conditions, time of year, ripeness of fruit and any external characteristics of possible internal defects.
When there are external indications of possible internal defects, such as riper fruit may have internal discoloration; the percentage of internal defects is based upon the entire sample examined. It is not based upon the number of fruit cut. For example, if an inspector examines a 50-count sample of nectarines, and after cutting 10 suspicious specimens finds 1 with an internal defect, the percentage of internal defects is 2%. (1 defective fruit out of the entire sample, 50 fruit in this case.) When it is known or suspected that internal defects are present, but there are no external indications of possible internal defects a random sample shall be used to determine percentages. Select and cut 10 fruit free from external defects from each sample. When any cut sample exceeds the container tolerance the sample should be doubled to 20 fruit. At least one entire container or 100 count should be cut to determine if the application of tolerances have been exceeded. If the lot fails to meet container tolerances after an entire container (or 100 count) has been cut, revert back to the above-mentioned plan of cutting 10 fruit free from external defects.
Simply put, you do not have to cut all of the nectarines in your sample. The USDA allows a smaller number to be cut (either 10 if 1 one less internal defects are found, or cut 20 nectarines if more than 1 nectarine is found with a scorable internal defect in your first 10 cut sample).