Combined effect of ultrasound and vacuum impregnation for the modification of apple tissue enriched with aloe vera juice

Summary in the original language of the document

The aim of the work was to investigate how ultrasonic (US) treatment impacts on the physical and chemical
properties of vacuum-impregnated apples. Apple slices were subjected to vacuum impregnation (VI) in an Aloe
vera juice solution without additional treatments, serving as the reference material. Alternatively, ultrasound
(US) treatments, at frequencies of 25 or 45 kHz, and durations of 10, 20, or 30 min, were employed as a pretreatments before the VI process. The use of US processing enabled a significant increase in the efficiency of
VI, without influencing in a significant way the color of the VI samples. The VI process led to a reduction in the
content of bioactive compounds, in particular vitamin C and TPC decreased by 34 and 32 %, respectively. The
use of US as a pre-treatment, in particular at 45 kHz for 20 or 30 min, led to a better preservation of these
compounds (unchanged values for vitamin C and decrease by 23–26 % for TPC in comparison to the fresh
samples). Through cluster analysis encompassing all assessed properties, it was evident that US treatment was
beneficial for the processing, however the application of appropriate parameters of US treatment (frequency and
time) had an impact on achieving similar quality to VI samples. The ultrasound treatment before vacuum
impregnation may be suitable, however, the specific processing parameters should be defined for the obtained
high quality of the final product.