COMPARATIVE COMPOSITION OF AERIAL AND SUBTERRANEAN POTATO-TUBERS (SOLANUM-TUBEROSUM L)

The composition of aerial and subterranean tubers of two potato genoty pes cvs Desiree (red skin) and Epicure (white skin) was compared immed iately after harvest using a range of analytical methods. Irrespective of genotype, aspartic acid, arginine, glycine, glutamic acid, histidi ne, leucine, serine, threonine and total amino acid concentrations wer e significantly higher (P < 0.05) in aerial compared with subterranean tuber tissue. Significant increases (P < 0.05) in valine in aerial tu bers, but no significant differences in alanine, tyrosine and iso-leuc ine, when compared with subterranean tubers of cv Desiree, were found. In cv Epicure, alanine, tyrosine and iso-leucine were significantly h igher in aerial tubers (P < 0.05); however, no significant differences in valine were recorded. There was no significant increases in lysine and phenylalanine between tuber types. Regardless of genotype alpha-s olanine, alpha-chaconine, chlorogenic acid, chlorophyll and crude prot ein concentrations were significantly higher in aerial tubers compared with subterranean ones (P < 0.01). No significant increases in total lipids between tuber types were found. In cv Desiree, ascorbic acid co ntent was not significantly different between aerial and subterranean tuber tissue, but in cv Epicure concentrations were significantly high er (P < 0.01) in aerial tubers. Starch concentrations were significant ly higher in subterranean tubers of both cultivars (P < 0.05). Sugar c ontent was significantly higher in aerial tubers of cv Epicure (P < 0. 01), but not significantly different between aerial and subterranean t ubers of cv Desiree. Regardless of genotype, phosphorus, magnesium, po tassium, zinc, manganese and sodium concentrations were significantly higher (P < 0.05) in aerial tubers. Iron and copper concentrations wer e significantly higher in aerial tubers of cv Desiree (P < 0.01), but significantly less in cv Epicure compared with subterranean tubers (P < 0.01, P < 0.05). Calcium concentrations were not significantly diffe rent between aerial and subterranean tubers of cv Desiree, but signifi cantly higher in aerial tuber tissue of cv Epicure (P < 0.01). Total g ross energy (mJ kg(-1) FW) was higher in aerial tubers of cv Desiree c ompared with subterranean tubers (P > 0.05), but not significantly dif ferent between aerial and subterranean tubers of cv Epicure. The poten tial applications of aerial tubers for industrial purposes are discuss ed.