A few of my posts have taken issue with the USDA not being specific, as to scoring guidelines, to ensure uniformity, for many defects. Whether the defect is considered damage or not a defect is left up to the judgement of the individual inspector.
The defect sunburn, on tomatoes, may go the other way. When reviewing the U.S. Grade Standards for Tomatoes there is no mention of the scoring guidelines for sunburn. But upon reading the USDA Inspection Instructions for Tomatoes there is a very specific guideline as to when you score sunburn as a defect, and when you don’t.
The following images depict sunburn in varying degrees.
The sunburn shown on the above image (Image 1) is very typical. The yellow discoloration is usually isolated to the shoulders and/or to one side of the tomato, the side of the tomato facing the sun, when growing.
On the Plum or Roma tomatoes (Image 2) the sunburn is found around the stem scar, or along the “sun” side of the tomato.
In extreme cases (Image 3), on many tomatoes found in my garden, the yellow discoloration is very obvious and the underlying flesh may also be affected.
The scoring guideline is not subject to objectivity. The USDA Inspection Instructions state the tomato is scored as a damage by sunburn when the area affected exceeds 20% of the surface area. Although most consumers would pick up all the tomatoes in the above images, they would also most likely put them down and choose a tomato without the sunburn, or yellow discoloration.
To demonstrate what 2o% of the surface would encompass, Image 4 shows you the area that would be allowed for sunburn. The yellow color would be aggregated, meaning you would merge all the yellow together and imagine if the total area affected would exceed the area of 20%. For example, in Image 4, would all the yellow exceed the 20% area? The answer is no, and aside from the growth crack, this tomato would not be a defect of the U.S. No. 1 Grade, due to sunburn. In fact only the two tomatoes, in Image 3 would be considered as being defects of the U.S. No. 1 Grade. All the other tomatoes in the above images would not be defects.