The influence of sugar composition on the colour stability of osmodehydrofrozen intermediate moisture apricots

Osmodehydrofreezing is a 'combined' process consisting of osmotic dehydration followed by air dehydration and then freezing. This process has been proposed to obtain intermediate moisture (a(w)=0.86) apricot ingredients without sulphur dioxide, having a natural and agreable colour, which could be suitable for different applications. The influence of the syrup composition [sucrose, maltose and sorbitol syrups with the addition of 1% (w/v) ascorbic acid and 0.1% (w/v) sodium chloride as antioxidant] on the chemical-physical properties of osmodehydrofrozen apricot cubes (10 mm) was studied. The effect of the modification of the glass transition temperature (Tg) through the osmotic pretreatment on the ascorbic acid retention and on the colour stability during storage at -20 degrees C was also analysed. The incorporation of different sugars into the apricot cubes modified the percentage distribution of the sugars and their low-temperature phase transitions. The sugar composition of the syrup affected the ascorbic acid retention during air-drying and the colour stability during the frozen storage, with maltose showing the highest protective effect. (C) 1997 Canadian Institute of Food Science and Technology. Published by Elsevier Science Ltd.