Filtration resistances in non-thermal sterilization of green coconut water

Sterile green coconut water was produced in a developed two stage laboratory scale constant pressure filtration system with a pre-filtration unit by ordinary filter paper (Whatman No. 4) for removal of suspended particles, and a micro-filtration unit by cellulose nitrate membrane (0.2 μm pore opening) for removal of microorganisms. The filtration performances of the systems were tested at three pressure differentials; 5.33, 10.67 and 16.00 kPa. Resistances in both the filtration processes and the cake compressibility factors were investigated. The filter medium resistance (Rm) and the cake resistance (α) increased with the increase in applied pressure differentials for both the filtration systems. The values of Rm varied between 3.497 × 109 and 5.042 × 109 m−1, and 1.979 × 1010 and 3.076 × 1010 m−1 for paper and membrane filter, respectively for the entire range of pressure differentials. The corresponding variations in α were 2.162 × 1012–4.280 × 1012 m/kg for paper filter and 2.144 × 1012–3.942 × 1012 m/kg for membrane filter. Although the Rm values for corresponding pressure differentials were high for membrane filter, the values of α were comparable for both the systems. The deposited cakes were compressible with a compressibility factor of 0.4.