International Produce Training


I am sure you have heard of the defects; sunburn and sunscald, but can you properly identify them?  Do you understand the difference?  As their name implies, these defects are caused by overexposure to the sun.  When a fruit or vegetable is overly exposed to the sun they take on different characteristics.  Most specimens will become yellow in color, some will take on a brownish color.

Let’s take a look at tomatoes, to discuss the differences between sunburn and sunscald.

Take a look at the image above.  This image illustrates the classic look of sunburn.  Although this is depicting sunburn on tomatoes, you could expect cucumbers, peppers, and watermelon to show the typical yellow discoloration of sunburn.  Sunburn results from heat stress leading to injury of the affected cells on the surface of the specimen.  Transpiration or evaporation of moisture helps cool the surface of the exposed surface area.  If the sun and or heat is gradual, the fruit or vegetable can adjust to the condition.  But the greatest problem occurs when they are suddenly exposed to high temperatures and intense sunlight.

Sunburn will always be found on one side of the specimen, the side exposed to the sun.  The discoloration will vary in intensity, from a light yellow to dark yellow color.  The surface may or may not be soft.

The image shown above depicts a tomato with suncald.  This is very typical of suncald affecting tomatoes, cucumbers, and peppers.  They all exhibit the dry, white bleached area.  Sunscald is also caused by sudden exposure to intense sunlight.  The affected cells are injured badly.  The killed tissue is bleached, gradually collapses forming a slightly sunken area, that may wrinkle.   The killed tissues encourage the development of secondary decay.  Sunscald  sometimes occurs during a period of light rain followed by intense sunlight.  The water, on the fruit or vegetable, acts as a magnifying glass, directing the sun’s rays onto its surface, killing off the cells.

So the difference between sunburn and sunscald is obvious, sunburn shows a slight yellow discoloration affecting the exposed area of a specimen, while sunscald is more serious, as the cells are killed by the sun and you will always see the sunken, dry, bleached area.  The USDA realizes the difference between the two defects, categorizing sunscald as a free from defect…meaning any amount of suncald would be a defect.  Sunburn is less serious, and depending on the product a specific area of sunburn is allowed, maybe a 1/2 inch area up to 5% of the surface.

No Comments on “Sunburn/Sunscald”

Leave a Comment