title: Factors affecting the content of the ursolic and oleanolic acid in apple peel: influence of cultivars, sun exposure, storage conditions, bruising and Penicillium expansum infection.
abstract: BACKGROUND
  For health promotion and as part of natural plant protection, it might be of interest to increase the content of oleanolic acid (OA) and ursolic acid (UA) by biofortification in breeding programs, although the extent of the influence of genetic and environmental factors needs to be clarified. The objective of this study was to determine the effect of cultivar, sun exposure, storage, bruising and fungal infection on the OA and UA content in apple peel.
  
  
  RESULTS
  Three apple cultivars with different ripening times--'Discovery' (early), 'Aroma' (middle) and 'Gloster' (late)--were investigated. The content of OA and UA was mainly influenced by cultivar and side subjected to sun exposure, and to a minor extent by storage and seasonal year. 'Gloster' had the highest OA and UA content of the investigated cultivars. OA and UA content on the shaded side was higher than that on the sun-exposed side in all three cultivars. Inoculation with Penicillium expansum did not have any consistent effect on OA or UA, except in a few cases where the levels decreased.
  
  
  CONCLUSIONS
  OA and UA content can be increased by choice of cultivar in the breeding process and to some extent by cultural practice.
authors.affiliation: Department of Plant Breeding, Swedish University of Agricultural Sciences, SE-23053, Alnarp, Sweden.
authors.forename: Yanrong
authors.initials: Y
authors.lastname: Lv
authors.affiliation: Department of Plant Breeding, Swedish University of Agricultural Sciences, SE-23053, Alnarp, Sweden.
authors.forename: Ibrahim I
authors.initials: II
authors.lastname: Tahir
authors.affiliation: Department of Plant Breeding, Swedish University of Agricultural Sciences, SE-23053, Alnarp, Sweden.
authors.forename: Marie E
authors.initials: ME
authors.lastname: Olsson
mesh_terms: D061353:Food Storage; D005638:Fruit / Q000737:chemistry* / Q000378:metabolism / Q000382:microbiology; D006863:Hydrogen-Ion Concentration; D027845:Malus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009828:Oleanolic Acid / Q000737:chemistry* / Q000378:metabolism; D010407:Penicillium / Q000502:physiology*; D013472:Sunlight; D013997:Time Factors; D014315:Triterpenes / Q000737:chemistry* / Q000378:metabolism; D000097245:Ursolic Acid
chemical_list: D009828:Oleanolic Acid; D014315:Triterpenes; D000097245:Ursolic Acid
keywords: apple; bruising; cultivars; fruit exposure side; health; oleanolic acid; triterpene; ursolic acid