Enhanced mass transfer of osmotic dehydration and changes in microstructure of pickled salted egg under pulsed pressure

Abstract

Pulsed pressure osmotic dehydration (PPOD) technology is much more effective than the traditional pickling for salted egg. This study was designed to compare the changes of water and salt in salted egg under five pressures and five pulsation frequencies in saturated brine solution (⩾25% NaCl (w/w)). Results showed that moisture content of both egg white and yolk significantly decreased with concomitant increase in salt content compared to traditional pickling. PPOD caused increases in water loss and salt gain of eggs and the optimal pressure and pulsation frequency were 160kPa and 7.5min/15min. Moreover, hardening ratio of egg yolk increased as pickling time and storage time increasing. About 2.92–15.63 fold diffusivity was found for the egg under PPOD compared to traditional pickling over the same time period. Environmental Scanning electron microscopic study revealed that yolk granule was aligned closely and became increasingly smaller after pickling.