Nonthermal sterilization of green coconut water for packaging

A laboratory scale technique for nonthermal sterilization of green coconut water was developed. The process consisted of two-stage filtrations under constant pressure using different filter media; namely, low ash filter paper (Whatman 42) in the first stage and cellulose nitrate membrane (0.2-mu m pore opening) in the second stage. The quality of the filtered water was evaluated with respect to microbial population, organoleptic characteristics, nutrient contents and physical properties. The water after the second stage of filtration was sterile with no visible growth of microbes on culture plates. The taste of the processed water did not change significantly; however, the flavor and overall acceptability decreased about 9 and 11%, respectively. The water also remained sterile after 1 month in aseptically packed condition, but overall acceptability further decreased by 6%. The filtration reduced different nutrients of the fresh water like fat, ash, total sugar, reducing sugar and protein by 40.0, 43.9, 23.4, 29.2 and 13.3%, respectively; the removal of K, Mg, Ca, Fe and Cu was 10.15, 16.14, 19.04, 20.85 and 22.21%, respectively. The removal of these nutrients increased surface tension and decreased viscosity of the coconut water.