1. Research Group for Chemometrics, Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden, Department of Surgical and Perioperative Science, Sports Medicine, Umeå University, SE-901 87 Umeå, Sweden, and Umeå Plant Science Center, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, SE-901 87 Umeå, Sweden