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Myrosinase stability in broccoli (Brassica oleracea var. italica). Influence of temperature and water activity
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Orientador(es)
Resumo(s)
Epidemiological studies have shown that a diet rich in Brassica vegetables is associated with
a decreasing risk of incidence of some types of cancer. These health promoting effects are
most likely due to the breakdown products of glucosinolates formed by the action of
myrosinase which catalyzes the hydrolysis of glucosinolates, found in Brassica plants.
Industrial processing of food can affect the content, composition, activity and bioavailability
of glucosinolates breakdown products, due to cell lysis or glucosinolates and myrosinase
degradation. The aim of this thesis is to investigate the combined effect of moisture content
(water activity) and temperature on myrosinase stability.
The study was conducted in batches of freeze dried broccoli with different moisture contents.
These batches of broccoli were then heated at different time/temperature combinations and
myrosinase activity was analysed, the obtained results from these measurements were
kinetically modeled.
Myrosinase was shown to be much less thermo stable in higher moisture content samples than
in the driest samples.
Thermal stability (30-80 ºC) of myrosinase was described by a first order kinetic model.
Besides showing higher myrosinase thermal stability, driest samples show lower activation
energies, i.e, lower increase of degradation rate when temperature increases.
Descrição
Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
Palavras-chave
broccoli Brassica oleracea var. italica myrosinase water activity temperature kinetics mirosinase actividade da água temperatura
Contexto Educativo
Citação
Castelo-Branco, João Diogo Cristovão Pinto - Myrosinase stability in broccoli (Brassica oleracea var. italica). Influence of temperature and water activity. Lisboa, Instituto Superior de Agronomia, 2010, 90 p.