Classification and differentiation of bottled sweet wines of Canary Islands (Spain) by their metallic content

Abstract

This study determines Na, K, Ca, Mg, Fe, and Cu contents in sweet wines bearing the denominations of origin of Lanzarote and La Palma islands (Canary Islands, Spain) from two consecutive harvests. Analyses were performed by flame atomic absorption spectrophotometry: Na, K, Ca, and Mg were determined in dilute samples and Fe and Cu in samples previously treated with nitric acid in a microwave oven. The denomination of origin of La Palma island has a high content in K, Ca, Mg, and Fe, while the denomination of origin of Lanzarote has a high Na and Cu content. ANOVA shows significant difference in content between these two islands for Na, K, Ca, and Mg, Na and Mg being the highest. Principal component analysis and cluster analysis show differences in the wines according to their geographical origin. Linear discriminant analysis shows a classification of 100% of wines in their categories. The best discriminant metals are Na and Mg, a geographical differentiation also being possible with these two metals only. Likewise, a joint study is made with the sweet wines of the denomination of origin of Malaga, it being possible to differentiate between Canarian and Malaga wines by using the content in Mg only. Again, separation of Lanzarote, La Palma, and Malaga was achieved only with Na and Mg metals.