[en] Six varieties of isano (Tropaeolum tuberosum), an Andean edible tuber, were analysed. The aim was to characterise qualitatively and quantitatively their content of glucosinolates and to determine concentration changes of these compounds upon delayed harvest. Additionally, exploratory assays were carried out on the effect of postharvest cold storage of the tubers as well as of a drying process imposed on blanched tuber slices. Only one glucosinolate (p-methoxybenzyl glucosinolate) was found in the six domestic varieties analysed. Its concentration varied between 36.5 and 90.0 mumolg(-1) dry matter. This range is relatively high when compared with other edible glucosinolate-containing vegetables. 'Dark' coloured tuber varieties showed higher levels than 'light' coloured tuber varieties at normal harvest time. Of the two varieties on which the effect of delayed harvest was studied, one showed increasing and then decreasing changes until 44 days after maturity, while the other did not show any significant change with time. Postharvest cold stored samples showed similar changes to tubers kept in soil, and glucosinolate levels in dried blanched tubers did not differ significantly from those in fresh samples. Taken together, the data indicate that the glucosinolate content of isano is highly dependent on both the variety and the time of harvest. These parameters should be taken into account when considering isano as a promising food source with medicinal properties for humans and animals, but also with possible adverse biological effects, all related to the presence of glucosinolates. (C) 2004 Society of Chemical Industry.
Johns T, Kitts WD, Newsome F and Towers GHN, Anti-reproductive and other medicinal effects of Tropaeolum tuberosum. J Ethnopharmacol 5:149-161 (1982).
Mithen RF, Dekker M, Verkerk R, Rabot S and Johnson IT, The nutritional significance, biosynthesis and bioavailability of glucosinolates in human foods. J Sci Food Agric 80:967-984 (2000).
Fahey JW, Zalcmann AT and Talalay P, The chemical diversity and distribution of glucosinolates and isothiocyanates among plants. Phytochemistry 56:5-51 (2001).
Wattenberg LW, Inhibition of carcinogenic effects of polycyclic hydrocarbons by benzyl isothiocyanate and related compounds. J Natl Cancer Inst 58:395-398 (1977).
Wattenberg LW, Inhibition of carcinogenic-induced neoplasia by sodium cyanate, tert-butylisocyanate and benzyl isothiocyanate administered subsequent to carcinogen exposure. Cancer Res 41:2991-2994 (1981).
Kjær A, Øgaard-Madsen J and Maeda Y, Seed volatiles within the family Tropaeolaceae. Phytochemistry 17:1285-1287 (1978).
Johns T and Towers GHN, Isothiocyanates and thioureas in enzyme hydrolysates of Tropaeolum tuberosum. Phytochemistry 20:2687-2689 (1981).
Bennett RN, Kiddle G and Wallsgrove RM, Biosynthesis of benzylglucosinolate, cyanogenic glucosides and phenylpropanoids in Carica papaya. Phytochemistry 45:59-66 (1997).
Porter AJR, Morton AM, Kiddle G, Doughty KJ and Wallsgrove RM, Variation in the glucosinolate content of oilseed rape (Brassica napus L.) leaves. I. Effect of leaf age and position. Ann Appl Biol 118:461-467 (1991).
AOAC, Official Methods of Analysis, 16th edn. Association of Official Analytical Chemists, Arlington, VA (1995).
ISO Rapeseed - Determination of Glucosinolates Content. ISO/NP 9167-1 (1999).
Benn M, Glucosinolates. Pure Appl Chem 49:197-210 (1977).
Goodrich RM, Anderson JL and Stoewsand GS, Glucosinolate changes in blanched broccoli and Brussels sprouts. J Food Process Preserv 13:275-280 (1989).
Wathelet J-P, Mabon N, Foucart M and Marlier M, Influence du blanchiment sur la qualité du chou de Bruxelles (Brassica oleracea L cv Gemmifera). Sci Alim 16:393-402 (1996).
Quinsac A, Charrier A and Ribaillier D, Glucosinolates in etiolated sprouts of sea-kale (Crambe maritima L). J Sci Food Agric 65:201-207 (1994).
Tawfiq N, Heaney RK, Plumb JA, Fenwick GR, Musk SR and Williamson G, Dietary glucosinolates as blocking agents against carcinogenesis: glucosinolate breakdown products assessed by induction of quinone reductase activity in murine hepa 1c1c7 cells. Carcinogenesis 16:1191-1194 (1995).
Fahey JW, Zhang Y and Talalay P, Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proc Natl Acad Sci USA 94:10367-10372 (1997).
Bateman JV, Una prueba exploratoria de la alimentación usando 'Tropaeolum tuberosum'. Turrialba 11:98-100 (1961).
Ramos GV, Ruiz C and Hilfiker J, Ensayo preliminar del estudio de la Mashua (Tropaeolum tuberosum) como suplemento comparado a un concentrado en la alimentación de becerros. V Reunion de Especialistas e Investigadores Forrajeros del Perú, Ayacucho, pp 121-133 (1976).
Guidi A, Informe Final del Proyecto: Uso del Isaño en la Alimentación de Cerdos en el Departamento de Cochabamba. Fundación PROINPA, Cochabamba (2001).
