Physical Properties and Volatile Profile Changes of Cauliflower Treated with Onion and Beetroot Juices Using Vacuum Impregnation Process.

The use of vacuum impregnation with onion and beetroot juice can help with the challenge of modifying plant tissue and fits in with current trends in the development of plant-based snacks. This study aimed to determine the effect of vacuum impregnation (VI) as a pretreatment before drying on the volatile compounds, texture profile, color, dry matter, water activity, and density of cauliflower. The pretreatment was carried out at a pressure of 0.06 MPa, and the total process time was 21 min. Two types of impregnation solutions were used: onion juice and beetroot juice. The samples were dried by freeze-drying and vacuum. Numerous volatile compounds were identified: twenty-two for raw cauliflower, twenty-nine for cauliflower after VI with beetroot juice, and twenty-four for cauliflower after vacuum impregnation with onion juice. The following volatile compounds were present in the highest amounts: 1-heptene, 2-methyl-(>60%), 2-ethylcyclobutanol (>4%), nona-3,5-dien-2-one (>1.8%), and two unidentified compounds, unknown 1 (probably an isomer of nona-3,5-dien-2-one (>1.8%)) and unknown 2 (probably a fatty acid) (>9.8%). The pretreatment had a significant effect on water activity, density, texture profile and color. The freeze-drying method proved to be effective in obtaining lower values of water activity and density. In addition, dried products obtained by this method were characterized by a higher degree of color recovery after rehydration and textural properties similar to fresh raw material. The use of different impregnation solutions had a significant impact on the properties studied. The greatest color change occurred in cauliflower treated with beetroot juice.