Browning of the apple fruit skin during storage
Barbara Stürz, Oswald Rossi, Angelo Zanella, Versuchszentrum Laimburg
The skin of apples can show superficial browning, which usually does not spread on to the below tissue. Reason for this browning is physiological, metabolic disturbances. While there are different types of browning, their damage pattern is hardly distinguishable from one another:
Superficial Scald: develops during storage, especially during Shelf-Life. Superficial, mostly blurry/diffuse browning of the skin. Doesn’t spread on the below pulp. Fruit skin can cave in/sink. Symptoms can spread fast at room temperature. Appears especially on early harvested fruits on specific varieties like Granny Smith or Red Delicious, mainly on their shady side, and is stimulated by high temperatures before harvest. Cause: Chilling at begin of storage, mainly on early harvested fruits.
Susceptible Varieties: Granny Smith, Red Delicious.
Prevention: on schedule-harvest, adapted to storage-duration and –technology, efficient storage with low oxygen levels. ULO-storage, treatment with 1-MCP. Alternative for very susceptible varieties: storage of fruits with dynamic controlled atmosphere (DCA) with low oxygen levels.
Senescent scald: superficial browning of the fruits, after longer storage sinking of tissue on affected spots; below pulp can brown too. Mainly on sunny side. On many varieties (like Golden Delicious), often due to late harvest, which results in too long storage. Cause: Late harvest or too long storage.
Susceptible Varieties: Golden Delicious, Jonagold and Idared.
Prevention: on schedule-harvest, adapted to storage-duration and –technology, efficient storage with low oxygen.
Diffuse Skin-Browning: Easily confused with Ordinary Browning, but no sinking of pulp on affected spots. The application of the 1-MCP can boost the Diffuse Browning. Especially problematic in regions with hot summer and little rainfall.
Cause: on fruits in warm growing area, which are treated with 1-MCP.
Susceptible Varieties: Golden Delicious, Granny Smith.
Prevention: ideal, gradual cooling and delayed 1-MCP application.
Sunscald: develops during storage on fruits that have been exposed to sudden, intensive sunshine in the field (i.e. through heavy summer pruning or thinning). Very dark, brown spots on the sunburned side of the fruit.
Cause: extent of sun intensity in the field.
Susceptible Varieties: Golden Delicious, Granny Smith.
Prevention: accurate choice of variety, hail nets-
Kontakt-Schalenbräune (Contact skin browning): thus far observed on the variety Stayman Winesap. Superficial, round browning on contact-points of the fruits.
Cause: Not known for sure. On variety Staman Winesap related to ripeness of fruits; mainly late harvested fruits are prone to this browning, especially if combined with unfavourable storage conditions.
Prevention: on schedule-harvest. DCA can hinder the development of contact browning on the variety Stayman Winesap.
Publications
Obstbau Weinbau (5); JG54; 13-15. |
Wenn die Apfelschale im Lager verbräunt Published: 01-05-2017 |
Documents