Influence of adsoption drying technologies on broccoli

The influence of the adsorption drying technology on stability and availability of glucosinolates in broccoli (Brassica Oleracea var. italica)

PhD fellow: Teresa Oliviero

 teresa.oliviero@wur.nl

Supervisors:
Prof. dr. ir.M.A.J.S. van Boekel (PDQ, WU);
Dr. ir. M. Dekker (PDQ, WU)
Dr. Ing. R. Verkerk (PDQ, WU)
Dr.ir. AJB van Boxtel (S&C, WU)
Prof. Ellen Kampman (HNE, WU)

Project term:
May 2009 – May  2013

Sponsors:
SenterNovem

Introduction

The consumption of Broccoli is known to be associated with health protective effect. The compounds responsible for this health effect are called isothiocyanates which are released when glucosinolates undergo hydrolysis by myrosinase (E. C. 3.2.3.147), an endogenous enzyme, during the disruption of broccoli tissues (chewing, chopping etc.). Isothiocyanates make Brassica vegetables ones of the most promising vegetables in colorectal cancer prevention (1).
Drying technology is an excellent way to preserve foods, nevertheless, it can result in the depletion of healthy compounds.
Absorption drying is a novel technology which uses low or moderate temperatures and can be regarded as a suitable option to fit the purpose of preserving the health effect of broccoli .

Aim

The aim of this study is to set up the most suitable drying conditions that preserves the health protective effect of broccoli by using the  adsorption drying technology. A kinetical modeling approach is used to study the effect of the process conditions on the chemical and enzymatic degradation of the target compounds. In addition, the effect of drying of broccoli on the bioavailability of glucosinolates and breakdown products will be investigated in a human intervention trial.

Research

Preliminary investigation shows that water content might affects the rate of glucosinolates
degradation during thermal treatment of broccoli. In order to investigate the influence of the water content/activity and temperature on
cell lysis, glucosinolates content, myrosinaseactivity and, in turn, on isothiocyanates potential formation, broccoli batches with different water content (obtained by using freeze drying process) are thermally treated to obtain mathematical kinetic models. These kinetic models will help setting up the parameters to gain the most suitable adsorption drying process.

Future research

The adsorption drying experiments will be designed according to the results coming from the preliminary investigations. Cell lysis, glucosinolates degradation, isothiocyanates formation as well as myrosinase activity will be investigated to gain the best adsorption drying conditions preserving as much as possible the health protective effect of broccoli.
Finally the effects of adsorption drying of broccoli on the bioavailability of glucosinolates in a human intervention trial will be studied, focusing on the role of myrosinase activity of intestinal microflora.

References

1. Voorrips LE, et al. (2000). Vegetable and fruit consumption and risks of colon and rectal cancer in a prospective cohort study: The Netherlands cohort study on diet and cancer. American Journal of Epidemiology, 152, 1081–1092.