Effects of high voltage electric pulses on protein-based food constituents and structures

High voltage exponential decay pulsed electric fields were applied to beta -lactoglobulin and ovalbumin solutions, dialysed egg white, lactate dehydrogenase and protein-stabilized model or food (o/w) emulsions. Electric processing did not induce significant unfolding or aggregation of beta -lactoglobulin or ovalbumin, as studied at different protein concentrations. The tetrameric enzyme lactate dehydrogenase was not inactivated after pulse processing. Thermal gels prepared from fresh or dialysed egg white had different mechanical properties, but pulse processing of dialyzed egg white only slightly affected the thermal gelling properties. Electric pulses tended to disperse large (10-15 mum) oil droplets in model emulsions (30% peanut oil, pH 6.0) stabilized with beta -lactoglobulin (5% w/w), or to dissociate large aggregates (60-70 mum) of fat globules in liquid dairy cream (35% fat, pH 6.7). However, the size distribution of oil droplets or fat globules in the studied emulsions was not markedly altered. (C) 2001 Elsevier Science Ltd. All rights reserved.