Vacuum impregnation on apples with grape juice concentrate: Effects of pressure, processing time, and juice concentration

Apple cubes were subjected to vacuum impregnation using grape juice concentrate. The effect of pressure reduction (VP = 100-500 mmHg), immersion time (t = 10-30 min), and concentration of grape juice (C = 40-60 degrees Brix) on impregnation parameters were evaluated using response surface methodology. Second-order polynomial equations were developed (R-2 >= 0.895) to describe the behavior of water loss, total soluble solids, L*, a*, Hue, total color difference, the color of impregnated/treated areas (A(U)/A(OP)), antioxidant activity, total monomeric anthocyanin, and dimensionless volume (V/Vo) in the impregnated product. VP had a significant (p <= 0.05) effect on mass transfer parameters, color parameters, A(U)/A(OP), and bioactive compounds. However, at 60 degrees Brix and 500 mmHg, the lower V/Vo values were reached due to cell disruption. Therefore, it is recommended to use a VP = 500 mmHg and t less than 20 min to significantly impregnate compounds and obtain a product without considerable morphometric modification.

Automated summary

This study investigated the effects of pressure reduction, immersion time, and grape juice concentration on the impregnation parameters of apple cubes. The results showed that pressure reduction had a significant impact on mass transfer parameters, color parameters, and bioactive compounds. It was recommended to use specific conditions to achieve impregnation without considerable morphometric modification.