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

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.

This research was funded by transnational funding bodies, partners of the H2020 ERA-NETs SUSFOOD2 and CORE Organic Cofunds, under the Joint SUSFOOD2/CORE Organic Call 2019 (MILDSUSFRUIT) as well as National Centre for Research and Development (POLAND, decision DWM/SF-CO/31/2021).
The research for this publication was carried out with the use of research equipment purchased as part of the “Food and Nutrition Centre – modernisation of the WULS campus to create a Food and Nutrition Research and Development Centre (CZ˙ iZ˙ )” co-financed by the European Union from the European Regional Development Fund under the Regional Operational Programme of the Mazowieckie Voivodeship for 2014-2020 (Project No. RPMA.01.01.00-14-8276/17).