Surface and center temperature of the mushroom, ambient humidity and temperature of vacuum chamber have been measured and recorded by the data logger inside the vacuum chamber (see Fig. 1). On the other hand, the control unit that records the pressure data is located outside the vacuum chamber (see Fig. 1). The measured data saved for each 10 seconds. Before starting the cooling, vacuum pump runs half an hour for stabilizing the system. Experiments carried out for three replicates and the average of these results has been used for this study. An electronic balance (Precisa XT 1220 M, ±0.001 g accuracy) has been used to determine the weights of the products before, after and during the cooling process.
The freshly harvested mushroom was bought from a local …show more content…
The composition of mushroom used for the study [74]
Components Mass Fraction (g/100g)
Water 91,81
Oil 2,09
Protein 0,42
Carbohydrate 4,65
Fiber 1,20
Ash 0,89
Using the Equation 1, 2 and Table 1, the specific heat of mushroom was calculated as 3993.49 J/kg°C.
Mass Balance Equation for the Vacuum Cooling.
Mass conservation for the control volume is given in Figure 2. As shown in the Figure, there is a single exit from the control volume and therefore, the mass rate balance reduces to:
〖dm〗_CV/dt=m ̇_initial 〖- m ̇〗_out 3
Where m ̇_initial is the mass in the vacuum chamber at the beginning, the m ̇_out is total mass flow rates out of the control volume, and 〖dm〗_CV/dt is the time rate of change of mass within the control volume. Since evaporation occurs during the cooling process from the product in the vacuum chamber, water balance in flowing air through the exit of the vacuum chamber leads to:
M_d 〖dM〗_ω/dt=-m ̇_(ω,out)=-m ̇_(a,out) ω_out 4
Where M_ω is the material moisture content, Md is the dry solid mass; ω_out denote exit air absolute humidity and m ̇_ais the dry air mass flow rate. In Equation 4, m ̇_ω is the mass flow rate of water in the air exit from the vacuum
The freshly harvested mushroom was bought from a local …show more content…
The composition of mushroom used for the study [74]
Components Mass Fraction (g/100g)
Water 91,81
Oil 2,09
Protein 0,42
Carbohydrate 4,65
Fiber 1,20
Ash 0,89
Using the Equation 1, 2 and Table 1, the specific heat of mushroom was calculated as 3993.49 J/kg°C.
Mass Balance Equation for the Vacuum Cooling.
Mass conservation for the control volume is given in Figure 2. As shown in the Figure, there is a single exit from the control volume and therefore, the mass rate balance reduces to:
〖dm〗_CV/dt=m ̇_initial 〖- m ̇〗_out 3
Where m ̇_initial is the mass in the vacuum chamber at the beginning, the m ̇_out is total mass flow rates out of the control volume, and 〖dm〗_CV/dt is the time rate of change of mass within the control volume. Since evaporation occurs during the cooling process from the product in the vacuum chamber, water balance in flowing air through the exit of the vacuum chamber leads to:
M_d 〖dM〗_ω/dt=-m ̇_(ω,out)=-m ̇_(a,out) ω_out 4
Where M_ω is the material moisture content, Md is the dry solid mass; ω_out denote exit air absolute humidity and m ̇_ais the dry air mass flow rate. In Equation 4, m ̇_ω is the mass flow rate of water in the air exit from the vacuum