Abstract: In order to explore the feasibility of replacing maltitol (MAI) as a sugar additive for yellow peach chips with isomalto-oligosaccharide (IMO), four pretreatments, i.e., ultrasonic (US), ultrasonic combined with isomalto-oligosaccharides (US + IMO), ultrasonic combined with maltitol (US + MAI), and ultrasound combined with combined sugar solution osmosis (IMO-MAI at a mass ratio of 1:1) (US + CSL) were applied to yellow peach slices. The moisture loss, solid increment, microstructure and water state of the pretreated samples were analyzed. Then, the samples were processed into yellow peach chips by either hot air drying (AD) or vacuum freeze drying (FD). The color, texture (hardness and brittleness), taste and major nutrient contents (total polyhenols, total carotenoids and VC) of yellow peach chips were determined. The results showed that the highest water loss rate of 23.36% was observed in the US + IMO treatment group, along with a solid increment of 2.25%, which were in line with the requirements of the national standard for food additives. Ultrasonic-assisted osmosis treatment led to increased porosity, cell wall distortion and consequent altered moisture state in peach slices as evidenced by a decrease in T23 from 357.07 to 310.78 ms, and increased the total carotenoids content of peach chips. The hot air dried peach chips with US + IMO pretreatment had the highest content of 47.87 mg/100 g, but showed a reduction in total polyhenols content, antioxidant capacity and VC content with the highest loss of 40 mg/100 g, while there were no significant differences among the different pretreatment groups (P > 0.05). In addition, the results of electronic tongue showed that the taste of the hot air yellow peach chips was similar to that of the freeze-dried ones irrespective of the ultrasound-assisted osmosis treatment used. Based on the above findings, IMO could be used to replace the traditional osmotic sugars (such as maltitol), which could improve the taste of the yellow peach chips. The yellow chips with US + IMO pretreatment could be served as a functional food to a broader range of consumers.

Key words: yellow peach, hot air drying (AD), vacuum freeze drying (FD), osmotic dehydration, isomalto-oligosaccharide (IMO), maltitol (MAI)