Abstracts now available online - Euro Fed Lipid

Application of pulsed electric fields at oil yield and phytosterols
content at the production of edible oils
Manuela Guderjan, Dietrich Knorr; University of Technology Berlin, Department of Food
Biotechnology and Food Process Engineering
Berlin, Germany
Vegetable oils and fats containing phytosterols are essential nutrients in the human diet.
They are beneficial especially due to their cholesterol lowering effect. The aim of the
current work was to study the impact of pulsed electric fields on the oil content, oil
quality and phytosterols content of wet milled corn germs in comparison to the different
separation methods solvent extraction, pressing as well as supercritical CO2 extraction.
The basic principle of the effect of pulsed electric fields is the permeabilisation of
biological membranes. In dependency of the impulse characteristic and the treatment
intensity, the permeabilisation can be reversible or irreversible. At a reversible treatment
of plant membranes at electric field strengths below 1.0 kV/cm stress is induced and the
production of secondary metabolites is initiated, whereas at field strengths higher than
1.0 kV/cm the cells are irreversibly stressed and pores are built. This leads to enhanced
mass transfer processes which is beneficial for oil extraction or pressing. Main
parameters for the pulsed electric field treatment are process parameters as electric
field strength, number of pulses, treatment time, pulse characteristics as well as a
homogeneity, sufficient moisture content and conductance of the probe, respectively.
In this work wet milled corn, steeped for 48 hr at 30°C, 40°C and 50°C in steeping
water, was irreversibly permeabilised at a field strength of 3.0 kV/cm and 120 pulses.
Subsequently, oil was separated by hexane extraction, pressing and supercritical CO2
extraction, respectively. At an electrical field strength of 3.0 kV/cm and a steeping water
temperature of 50°C the oil yield could be increased by 27.8 % at hexane extraction, by
25.2 % at pressing and by 14.9 % at supercritical CO2 extraction. Further increase of oil
yields could be reached by the combination of pressing and hexane extraction as well
as CO2 - and hexane extraction. Most phytosterols could be gained by the supercritical
CO2 extraction. By the application of pulsed electric fields no quantitative variances of
the content of stigmasterol, sitosterol and campesterol were obtained, whereas, at the
CO2 extraction more sitosterol was determined.
From the established results a concept for the wet milling process of corn to enhance
the oil yield and to produce an oil with an additional nutritional benefit by the application
of pulsed electric fields was developed.
In current investigations the impact of pulsed electric fields on the oil yield and content
of different functional food ingredients at the production of rapeseed is studied.
P2