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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]

A study was conducted to investigate the effects of apple juice concentrate and blackcurrant concentrate (BCC) syrup mixture level, osmotic soaking time and drying temperature on the drying characteristics and ascorbic acid content of the dried product using the response surface methodology, as well as to determine the optimized conditions for hot air drying of the blackcurrant-infused apple cubes. The drying of blackcurrant-infused apple cubes consist of only one falling rate period (FRP) with no constant rate period. The critical moisture content of infused apple cubes increased with decreasing soaking time, the FRP drying coefficient increased with temperature, the equilibrium moisture content decreased with increasing temperature and decreasing soaking time and the ascorbic acid content increased with BCC level and soaking time. The optimized conditions for hot air drying of the blackcurrant-infused apple cubes were derived. [ABSTRACT FROM AUTHOR]