This paper presents a comprehensive review of recent developments in thermal (radio frequency,
microwave and ohmic), non-thermal (high pressure, ultrasound and infrared)
methods in blanching pretreatment. Recent developments in quick freezing technology (high
pressure, dehydrofreezing and ultrasound-assisted) as applied to freezing of fruits and
vegetables are also reviewed. The thermal and non-thermal blanching methods provide
rapid and uniform heating; reduce the loss of soluble nutrients and minimize thermal
damage compared to conventional hot water blanching. High pressure freezing seems to
promote instantaneous and homogeneous ice nucleation in fruits and vegetables. Dehydrofreezing
is capable of reducing the damage to plant texture by removal partial of water
before freezing. Ultrasound-assisted freezing is found to be effective in the initiationof nuclei
and subsequent growth of crystals. More fundamental researches are needed for better
design and scale up, so that these technologies can be transferred from laboratory to
industry.