Classification of Spanish unifloral honeys by discriminant analysis of electrical conductivity, color, water content, sugars, and pH

To ascertain the most discriminant variables for seven types of Spanish commercial unifloral honeys, stepwise discriminant analysis was performed. Fifteen parameters [pH; water content; electrical conductivity; x, y, and L, chromatic coordinates from the CIE-1931 (xyL) color space; fructose; glucose; sucrose; maltose; isomaltose; maltulose; kojibiose; and the fructose/glucose and glucose/water ratios] were considered. The studied honey types were rosemary, citrus, lavender, sunflower, eucalyptus, heather, and forest. The most discriminant variables, as selected by the multivariate program, were electrical conductivity, color (x, y, L), water content, fructose, and sucrose. All sunflower, eucalyptus, and honeydew honey samples and >90% of the samples from the remaining honey types were correctly classified by using the classification functions devised by the program. The overall proportion of accurately arranged samples was 95.7%. Results were validated by the "jackknifed" procedure and showed that electrical conductivity, color, water content, fructose, and sucrose are highly useful parameters to classify unifloral honeys, although microscopical analysis of honey sediment remains the fundamental tool.