Response of spinach in controlled pressure conditions during vacuum pre-cooling

The decrease in pressure inside the enclosed chamber was controlled between 2.4 kPa and pre-set minimum pressure of 0.61 kPa to follow a linear and exponential decay functions during vacuum pre-cooling. The change in the pressure profiles, which reduces cooling rates, increased moisture loss and decreased temperature reduction per percent mass loss regardless of the functions used. At vacuum chamber's final pressure of 0.61 kPa, the L-ascorbic acid (Vitamin C) in spinach declined by 24% as compared to the samples cooled using 0.8 and 1.0 kPa. The results implied that a critical pressure exist by which the quality is affected. Copyright (C) 2001 IFAC.