Exploring the effects of vacuum and ultrasound treatments on calcium fortification in osmotically dehydrated apple slices

Abstract

This study aimed to investigate the impact of vacuum (VC) and ultrasound (US) treatments during osmotic hydration (OD) at 25 °C on the impregnation of calcium into apple tissues. The VC and US treatments were applied in two modes: a) VC or US at the first 10 min of the OD process and b) treatment with 10-min intervals during OD. Under the experimental conditions used in this study, the results revealed that the interval ultrasound treatment was the most effective in enhancing mass transfer and calcium uptake among all the treatments. It exhibited the highest efficiency in moisture removal and calcium uptake, resulting in a calcium content of 3,644.19 μg/g dry basis, over 18 times higher than that found in fresh apples. The calcium content in OD-treated apple slices remained well-preserved after hot air finish drying. Additionally, the samples treated with VC and US exhibited high total phenol content and antioxidant capacity, suggesting their ability to retain bioactive compounds in the apple slices. Overall, this study highlights the efficacy of VC and US treatments during OD in promoting calcium impregnation into apple tissues, with the interval ultrasound treatment yielding the most favorable results in terms of calcium uptake, moisture removal, and nutrient preservation.