POSTHARVEST QUALITY OF TWELVE ONION CULTIVARS GROWN IN THE SOUTHEAST OF BRAZIL
Onions (Allium cepa L.) are grown in different parts of the Brazilian territory and are considered the third most important vegetable crop cultivated in the country, only behind potatoes and tomatoes. The present work was carried out aiming to evaluate the postharvest quality of twelve different onion cultivars grown in the Southeast of Brazil. Onions of the cultivars Adocicada, Branca, Picante and Roxa were harvested in commercial fields and the cultivars Princesa, Serrana, Bulbo duplo, Granex 33, XP 6803, XP 8418, RP 6010 and Superex were obtained in experimental fields. After harvest, bulbs were taken to the postharvest laboratory and evaluated for total soluble solids, titratable acidity, and pungency (aliinase activity). For total soluble solids Superex had the lowest sugar content (5.4°Brix) whereas the cultivar named Picante showed the highest Brix (11.0°Brix) among the studied materials. For titratable acidity, it was verified that Serrana had the lowest acid content (0.094 g piruvic acid.100 g-1 FW) whereas Branca showed the highest content of organic acids. When pungency was evaluated it was verified that aliinase activity varied from 1.37 µg piruvic acid.100 g-1 FW for Adocicada to 12.18 µg piruvic acid.100 g-1 FW for Roxa, which was considered to have hot pungency (high alliinase activity and low TSS/TA), whereas Bulbo duplo was evaluated as pungent (high alliinase activity and TSS/TA). The combination of the studied characteristics indicated that an onion with high pungency must have high aliinase activity and titratable acidity, whereas sweet onions shall have high soluble solids contents and low aliinase activity. Based on this information, Branca bulbs were considered acids (weak pungency and high acidity), whereas Adocicada, Princesa, and Serrana bulbs are sweet, due to low alliinase activity and titratable acidity. Superex, XP 6803, Granex 33 and Picante had a moderately pungent flavor (alliinase activity intermediate and low TSS/TA), but XP 8418 and RP 6010 flavor was evaluated as lightly pungent (low alliinase activity TSS/TA).
Miguel, A.C.A., Durigan, M.F.B., Durigan, J.F. and Moretti, C.L. (2005). POSTHARVEST QUALITY OF TWELVE ONION CULTIVARS GROWN IN THE SOUTHEAST OF BRAZIL. Acta Hortic. 688, 265-268
Allium cepa, aliinase, pungency, titratable acidity, total soluble solids