ABSTRACT
In the last years, consumers interest on getting healthier foods has promoted the 
functional foods market, defining a functional food as any foodstuff that provides a 
health benefit beyond that supplied by its essential nutrients.
Among different techniques employed in the manufacture of functional foods, vacuum 
impregnation allows to incorporate physiologically active compounds to certain foods 
without disrupting their cellular structure, but probably affecting their behaviour during 
their further processing.
In this work an attempt is made to analyse how the amount of calcium incorporated to 
the porous structure of apple slices (var. Granny Smith) by means of vacuum 
impregnation affects mass transfer kinetics taking place during osmotic dehydration 
and hot air drying under different conditions. Besides this, with the aim of checking this 
mineral capability to prevent cell structures degradation, changes in mechanical 
properties of apple slices during their processing together with the behaviour of hot air 
dried samples during their rehydration by immersion in water have been also analysed.
During the manufacture process of apple slices fortified with calcium by combining 
vacuum impregnation and osmotic dehydration, the highest yield was reported after the 
experiments carried out with the samples impregnated with the highest concentration of 
calcium tested (IV sac+40% CDR Ca), at moderated temperature (30-40 °C) and with 
the 55 Brix sucrose solution that included 1% of calcium lactate on its composition. 
Despite these samples resulted firmer, their calcium content was lower than that 
obtained at 50 °C and their external aspect was not as good as that obtained when 
working with samples impregnated with a solution containing a lower concentration of 
calcium (Iv sac+20% CDR Ca).
With respect to the manufacture process of apple slices fortified with calcium by 
combining vacuum impregnation and drying with air at a certain temperature, the 
increase in the kinetics of the process with the increase in the calcium content of the 
impregnating solution has been explained in terms of the higher firmness of the tissue 
and the lower energy required in these cases to deform the structure. Results obtained 
after low moisture samples rehydration also corroborated the lower damage caused to 
the cellular matrix during hot air drying of samples with high calcium content.