p‐Hydroxyacetophenone and Picein contents of healthy and damaged spruce needles from different locations in Bavaria

Picein can quickly be converted into p‐hydroxacetophenone by endogenous glucosidases activated by freezing and thawing of spruce needles. Picein was the main component of all investigated spruce needles. Its contents varied between 4 and 30 mg/g fw whereas p‐hydroxyacetophenone (pHAP) concentrations between 0.2 and 0.6 mg/g fw were found. No significant difference for picein and pHAP contents were observed comparing green and bleached needles or needle segments. In each case the ratio of pHAP to picein was smaller than one for both green and bleached needles. The importance of pHAP for pigment bleaching is discussed.