Author : de la Torre, Jerry James M.; Gragasin, Ma. Cristina B.; Caparino, Ofero A.

Summary : As a fundamental step in developing a vacuum evaporator for small scale processing of concentrated coconut water in the rural areas of the Philippines, the mechanism of evaporation under vacuum pressure was investigated in terms of volume reduction, sugar concentration and stability over the process time. The water from the young coconut was subjected to vacuum evaporation (50 mbar) for up to 90% moisture removal. Considering the coconut water is composed mostly of water and sugars, distilled water and sugar water solution (5%) samples were similarly subjected to vacuum evaporation alongside the tender coconut water. The water removal from these samples proceeded linearly within 35 minutes from an initial 100 ml volume. The experiments showed further that the evaporation of water from coconut water (y=2.4349x+0.8344,R2= 0.9941) was significantly lower than both distilled water (y=2.6739x+1.9138,R2= 0.9966) and sugar solution (y=2.614x +2.9511,R2=0.9917). As the water is liberated from the samples, the sugar gets concentrated exponentially in the coconut water (y=4.2396e0.0538x,R2=0.977) and sugar solution (y=4.5596e0.0567x,R2=0.9805). In terms of stability, the experimental samples showed the water activity going down over the process time according to second degree polynomial fit: young coconut water, y=-0.003x2+0.0054x+0.9 841,R2=0.8972; sugar solution, y=-0.00009x2+0.0018x+0.9537,R2=0.9236; These findings are useful in sizing and controlling the hardware components of the prototype vacuum evaporator for village level processing of coconut water concentrate.