The use of vacuum impregnation technique on the enrichment of fresh cut apple with natural colorant and some additives

In this thesis study, fresh apple slices were enriched with calcium and black carrot juice as a natural colorant using vacuum impregnation technique and thus a new functional food was developed. A novel equipment was designed by combining ultrasound to vacuum system to facilitate the vacuum impregnation efficiency. The study consisted of four steps. In the first step, the concentrations of substances dissolved in vacuum impregnation solution were determined. In the second step, the optimum vacuum impregnation process parameters were determined by response surface methodology. In the third step, the effect of combined utilization of ultrasound at various powers was tested. In the fourth and last step, the physical and microbial qualities of apple discs produced at optimum conditions were investigated during the storage period. The most preferred impregnation solution formulation was determined as 3% Ca-lactate, 3% lactic acid and 0,8% black carrot concentrate within 0,2 M mannitol by considering the results of calcium, lactic acid, bioactive compound contents, texture, color and sensory analyses of products. Optimum process parameters according to highest colorant transfer while the minimum cellular disruption occurs were determined as 211 mmHg vacuum pressure, 3 min vacuum time and 20 min restoration time. The combined ultrasound with vacuum impregnation at 35 kHz frequency and 130 W/L led to 25% increase in the anthocyanin transfer into apple tissue. The highest compound transfer was achieved at continuous running of ultrasound compared to single run at vacuum or restoration period and thus it was concluded that the ultrasound is also effective during vacuum step.