Studies on the Effect of Mass Transfer in Vacuum Impregnation on the Bioactive Potential of Apples

Abstract

The purpose of the study was to evaluate the efficiency of mass transfer during vacuum impregnation (VI) of apple tissue by different process conditions. VI was carried out in two stages: Vacuum (4, 6, or 8 kPa maintained at time 10, 20, 30, 40, 60, and 80 s) and atmospheric (4 min under atmospheric pressure). As infiltration liquids, fresh squeezed apple-pear juice (J), 3% citric acid solution (C), and distilled water (DW) were used. Mass transfer was analyzed based on three factors: Mass variation (MV), dry mass variation (DMV), and solid gain (SG). The outflow of native components and inflow of infiltration liquid has been described by mathematical models. The polyphenol content and antioxidant capacity (ABTS+, FRAP) were evaluated as the bioactive potential factors confirming native component outflow and incorporation of liquid molecules into an apple tissue. It was found that during VI of an apple tissue, intensive mass transfer occurred: Native components of fruit tissue outflowed and external ingredients of impregnation liquid inflowed into the material with the intensity proportional to the vacuum level and process time. The most beneficial conditions of apple cube VI were noticed at a vacuum level of 4 kPa for a minimum of 40 s, which is when the highest polyphenol content and antioxidant capacity occurred.

Physicochemical and Quality Properties of Dried Courgette Slices: Impact of Vacuum Impregnation and Drying Methods

“…This resulted from the introduction of valuable compounds from the vegetables from which the juice was squeezed. Impregnation in a salt solution is a typical osmotic dehydration process that causes an intensive outflow of internal tissue water together with native bio components [ 38 ], whereas vacuum impregnation in vegetable juices let to incorporate valuable ingredients from the juice into the material processed [ 12 ].…”

“…Vacuum impregnation was performed in a prototype plant located at the Institute of Agricultural Engineering, Wroclaw University of Life Sciences (Wroclaw, Poland) [ 12 ]. Samples weighing 120 g were placed in a perforated stainless steel vessel.…”

“…In order to select the appropriate model that best described the process flow, an RMSE analysis was performed, along with aiming to reduce the X 2 test values and coefficient of variation of the residual V e , using the relationship: where MR i,p is the calculated (predicted) relative water content, MR i,e is the experimental relative water content, N is the number of observations, n is the number of parameters in the model equation, and Y is the mean experimental relative water content, MR [ 12 ].…”

“…Diverse and innovative food preservation methods used in the food industry provide opportunities to improve the functional properties of food products and help to meet market demands [ 11 ]. Vacuum impregnation (VI) is a type of osmotic dehydration carried out under vacuum conditions [ 12 ]. While the kinetics of osmotic dehydration and the effect of process conditions on product quality are well understood, the vacuum impregnation of biobased materials involves many aspects that remain to be investigated [ 13 ].…”

“…While the kinetics of osmotic dehydration and the effect of process conditions on product quality are well understood, the vacuum impregnation of biobased materials involves many aspects that remain to be investigated [13]. Vacuum impregnation (VI) is a novel method that uses pressure change to remove intercellular air (with some native fluids) from plant tissue without destroying the initial cellular structure [12,[14][15][16][17]. When atmospheric pressure is restored, the pores and intercellular spaces fill with the impregnating liquid, which allows for the direct production of foods with altered quality characteristics [12,14].…”