A fruit juice containing 30% solids of molecular weight 100 g was placed in a tray (length =100 cm, height = 90 cm, width = 8 cm) in the freezer that uses propylene glycol that is at -30 C(celsius). The convective heat transfer coefficient between the product and the glycol is 200 W/m^2 K. If the specific heat,density, and thermal conductivity of the unfrozen product are 4000 J/kj K, 950 kg/m^3 and 0.5 W/m K respectively and that of the frozen product are 3900 J/kg K, 900 kg/m^3 and 1.6 W/m K respectively, Determine the time taken for the product to freeze if it is at its initial freezing point when it was placed in the blast freezer.