Optimisation of vacuum impregnation of blackcurrant-infused apple cubes: application of response surface methodology.

The response surface methodology was used to investigate the effects of blackcurrant concentrate level, vacuum pressure and time on the mass transfer and nutritional properties of vacuum-impregnated apple cubes. There were higher water loss and weight reduction in the samples at the middle-level vacuum pressure, but the other factors had no effect on these properties. The higher the vacuum pressure and time, the higher the solids gain of the samples. There was opposing results of the antioxidant capacity of the samples in the middle and high blackcurrant concentrate level and vacuum pressure when compared with the low blackcurrant concentrate level and high vacuum pressure. The middle blackcurrant concentrate level gave higher ascorbic acid content of the samples, while the middle vacuum pressure gave lower values. The optimised conditions for vacuum impregnation of the apple cubes were 18-20% blackcurrant concentrate level, 77-80 kPa vacuum pressure and 38-45 min vacuum time. [ABSTRACT FROM AUTHOR]