Glassiness
Glassiness is a metabolic disease of apple caused by an impaired glucose metabolism occurs.
Clinical picture
Even before Apple's picking time has been reached, glassy bodies develop in the flesh . These often arise first around the core housing or around the vascular bundles and can later be located directly under the shell . The affected pulp appears watery and transparent. The spaces between the cells are not filled with air as usual, but with cell sap . However, the disease can regress during storage, which is why the glassiness is often only noticeable in freshly harvested fruits. In the case of a very pronounced clinical picture, however, the glassiness can lead to further storage diseases , such as meat browning.
Cause of illness
The cause of the glassiness is a metabolic disorder of the apple fruit . A disturbed sugar metabolism leads to a strong breakdown of starch within a relatively short time. The resulting increase in the sugar concentration leads to an altered osmotic potential within the pulp, which means that the cell juice gets into the spaces between the cells. Due to the lack of oxygen, fermentation processes continue to occur within the fruit, whereby alcohol and acetaldehyde can form. The exact causes of this metabolic disorder are unknown.
Factors that are conducive to glassiness:
- Wide leaf / fruit ratio (many leaves on too few fruit)
- Long assimilation period (late harvest )
- Good assimilation conditions (good climatic conditions )
- Calcium deficiency
- Variety choice
Interim storage of the apples at 10–15 ° C before the actual storage can accelerate the regression of glassiness.
Variety choice
The following are considered glassy-sensitive: Alkmene , Cox Orange , Fuji and Gloster .
Others
Since it is almost impossible to recognize the glassiness based on the external appearance, research is being carried out on imaging processes , for example using X-rays or magnetic resonance tomography .
Glassiness is not only a problem with apples, it also occurs in many plants in vegetable growing . The reason for this, however, is not due to the sugar metabolism, but mostly arises from excessive water intake.
Individual evidence
- ↑ a b CP HARLEY: Water-core [of Apples], Proceedings . Washington State Horticultural Association. 1934, pp. 105-108.
- ↑ a b c d Fritz Winter: Lucas' instructions for fruit growing . Ulmer, 2002, p. 363.
- ↑ a b Glassiness in vegetable growing . As of November 2, 2014.
- ↑ S. Kim, TF Schatzki: Apple watercore sorting system using X-ray imagery: I. Algorithm development, Transactions of the ASAE . Vol. 43, No. 6, 2000, pp. 1695-1702.
- ^ S. Y Wang, PC Wang, M. Faust: Non-destructive detection of watercore in apple with nuclear magnetic resonance imaging, Scientia Horticultura . Volume 35, Issues 3-4, 1988, pp. 227-234.