Use of Thermotherapy and Natural Antifungal Compounds against Post Harvest Diseases on Apples

Summary

In France, short hot water treatment (2/3min.) can now be applied in food industry. As far as Ph/yctaena vagabunda is concerned (Ienticel spot disease or
-G/oeosporiuma) hot water treatments are very effective. We know now more about the hot water risk injuries : only a few varieties can be treatAn .aL52. aC. By contrast, at 50°C a lot of varieties are not susceptible tO hot water risk injury. Unfortunately Golden delicious apples can not b_e_trèai.acLlt-5G-2Cf3 min., a slight change of skin coloration is unacceptable commercially. In fact, Golden delicious apples are the most susceptible to thermotherapy. In this case it is possible however to lower the temperature up to 48 aC. Such a treatment is completely safe for ali varieties assayed, but the efficacy is less than the 50 aC treatment.
In that case we can use some natural antifungal compounds extracted from edible plants.
Eugenol and natural clove oil, have been selected in our laboratory as the best antifungal compounds in fight lenticel spot disease. Considerable experiments have been performed on Golden delicious apples, finally a combination of hot water treatment (48 aCf3 min.) and eugenol (1,5g a.i.ll) gives a hight efficacy without any skin injury. A prolonged antifungal effect was obtained as expected.
Hot water treatment can be applied immediatly in food industry. In the case of eugenol,
we have to wait 2003 to get it commercially available for organic farmers (XEDA INTERNATIONAL).
If we are able in food industry to combine hot water treatment, the use of natural compounds and for biofungicides (such as yeasts), it could be reasonably envisaged to obtain a very high efficacy close to that of chemical treatments.