The Effects of Applying Oscillating Magnetic Fields During the Freezing of Apple and Potato

Abstract

The use of Oscillating Magnetic Fields (OMF) during freezing has been advocated by some for preserving the intrinsic ‘fresh’ qualities of the subsequently thawed food. This paper describes studies to investigate the effects of a range of different OMF freezing settings using an ABI Cells Alive System (CAS) freezer on characteristics of the freezing process and food-quality parameters. The effects of short-term frozen storage on sample properties were also evaluated. Apple and potato samples were frozen at − 30 or − 45 °C with a range of OMF settings whilst measuring sample temperatures. Samples were then either immediately thawed or stored frozen for 1 month. Effects of OMF on freezing temperature curve texture parameters, sample dimensions, sample weights and sample texture parameters of thawed samples were determined. Overall, results showed no statistically significant continuum of effect in these trials that prevails across all CAS settings and/or temperatures for apple and potato for any parameter measured. However, significant effects were seen at some settings for some parameters for each product, and this may suggest that OMF may possibly be tuneable for specific situations. Where significant changes did occur, these only appeared at isolated settings, temperatures or storage periods. This suggests that OMF may not affect all foods in an equal manner and that any effect depends on an interrelationship of food type, freezing rate, magnetic field frequency and storage conditions. We conclude that there is no major effect of OMF on freezing parameters and there is no overall pattern of OMF on freezing processes.