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Vacuum impregnation (VI) allows soluble solids to be introduced into the porous matrix of a food material, modifying the composition of the tissue to facilitate further processing. The purpose of this research was to analyze the influence of pressure on the effectiveness of VI on a low porous material that is difficult to impregnate. Two cultivars of carrot (Baltimore F1 and Komarno) were subjected to VI at 5 and 30 kPa in a ternary solution of ascorbic acid (0.5%), citric acid (0.5%), and sucrose (8%) under isotonic conditions. The products were analyzed in terms of ascorbic acid content, degree of impregnation, and changes in structure, texture, color, antioxidant activity, phenolic content, carotenoids, and structure-forming compounds. Increases in vitamin C content (after VI) depended on the process conditions and ranged from 900% to 1300% in relation to the raw material. It was also observed that the extended impregnation time at a pressure of 5 kPa produced slices that were also impregnated in parenchyma area. The increased levels of polyphenolic compounds found in the saturated product may suggest that de novo synthesis under the influence of physiological stress had occurred. [ABSTRACT FROM AUTHOR]

Featured Application: Depending on the way of industrial processing, specific properties of apple fruit are required. The fruit of some cultivars has characteristics that predispose them to the production of juices or purees. Other properties are important for the vacuum impregnation process. The results obtained will be useful in the case of industrial application of the vacuum process of apple tissue. The article evaluated the suitability of 14 apple cultivars for the vacuum impregnation (VI) process based on the comparison of the physicochemical properties of fresh and impregnated tissue. The cube-cut apple was impregnated in a solution close to isotonic composed of 0.5% ascorbic acid, 0.5% citric acid, and 10% sucrose. The VI process was conducted with vacuum time and absolute pressure at 10 min and 15 kPa, restoring atmospheric pressure at 5 min and relaxation time at atmospheric pressure at 10 min. The content of ascorbic acid after VI increased by 3 to 25 times and was in the range of 73.5–130 mg/100 g, while the mass gain for the samples ranged from 15% to 34%. On the basis of the Pearson correlation, it was found that the mass gain was negatively correlated with the firmness of the fresh apple cubes (r = −0.85). The cultivars with favorable features after the VI process in terms of vitamin C content; hardness; and browning index (BI) are Cortland; Shampion; and Ligol. [ABSTRACT FROM AUTHOR]