Activity of the enzymes pectinmetylesterase and polygalacturonase during the ripening of tomatoes of the multilocular group

• Autor(es):

  Resende, Josane Maria (Universidade Federal de Lavras. Departamento de Ciência dos Alimentos);

  Chitarra, Maria Isabel F. (Universidade Federal de Lavras. Departamento de Ciência dos Alimentos);

  Maluf, Wilson Roberto (Universidade Federal de Lavras. Departamento de Agricultura);

  Chitarra, Adimilson Bosco (Universidade Federal de Lavras. Departamento de Ciência dos Alimentos);

  Saggin Júnior, Orivaldo José (Universidade Federal de Lavras. Departamento de Ciência dos Alimentos).

• Fonte:

  Horticultura Brasileira; volume 22, número 2, páginas 206-212. Junho 2004.

• Assuntos:

  Lycopersicon esculentum;

  F1 hybrids;

  alcobaça;

  Crimson;

  high pigment;

  plant breeding;

  softness;

  post harvest conservation.

• Resumo:

  The activity of the enzymes pectinametylesterase (PME) and polygalacturonase (PG) was measured in tomato fruits of the multilocular group at various maturation stages, to obtain the correlation to changes in texture, pectin and lycopene. Fruits were harvested at the mature-green stage and ripened in a room with 85-90% relative humidity and 20ºC±2 room temperature. Throughout storage, samples were taken to assess enzymes activity of PME and PG at the maturation stages: mature green, breaker, ripe and red-ripe. The other variables were surveyed only after the red-ripe stage of fruits. Among the evaluated genotypes, three hybrids H3: F1 (BPX 308B hv x Stevens), H8: F1 (BPX 308B hv x Piedmont) and H1: F1 (BPX 308B hv x BPX-127H) stood out with best characteristics for natural consumption when compared to control, showing the least enzymes activities of PME and PG which led to a decrease in depolymerization and solubilization of pectin, causing an increased texture. In addition, larger pulp thickness and smaller numbers of locules of these hybrids also contributed to the texture increase, improving shelf life and fruit quality. The low activity of the enzyme PG did not affect the development of color, an important trait for acceptance of the fruit by consumers. The hybrid H1: F1 (BPX 308B hv x BPX-127H), containing the alc gene in heterozigosis, which improves post-harvest conservation, was the third best hybrid for consumption. Presenting the alc gene in heterozigosis and, without detrimental effect in coloration, this hybrid may be a viable option for tomato plant breeders to improve post-harvest preservation.

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