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Please use this identifier to cite or link to this item: http://hdl.handle.net/10400.5/2881

Title: Myrosinase stability in broccoli (Brassica oleracea var. italica). Influence of temperature and water activity
Authors: Castelo-Branco, João Diogo Cristovão Pinto
Advisor: Martins, Margarida Moldão
Keywords: broccoli
brassica oleracea var. italica
myrosinase
water activity
temperature
kinetics
mirosinase
actividade da água
temperatura
Issue Date: 2010
Publisher: ISA
Citation: 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.
Abstract: 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.
Description: Mestrado em Engenharia Alimentar - Instituto Superior de Agronomia
URI: http://hdl.handle.net/10400.5/2881
Appears in Collections:BISA - Dissertações de Mestrado / Master Thesis

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