Abstract
We examined sterile filtration of apple juice by ceramic microfiltration (MF) membrane to develop apple juice production technique in which long term storage was possible without heat sterilization. Under the operating condition at 3.5 m/s crossflow velocity and at a mean transmembrane pressure of 0.20 MPa, it was possible to get 95% permeated juice, and the average flux was about 35 l⋅m-1⋅h-1. The MF membrane after the juice treatment was cleanable by using a mixed solution of sodium hydroxide and sodium hypochlorite at 70°C for 30 min; 100% recovery of pure water flux was attained. It was confirmed that the high value on the logarithmic reduction value (LRV) ≥13.0 in challenge test using Brevundimonas diminuta and Streptococcus faecalis. The color and sensory tests after long storage periods showed that the quality of MF permeated juice was better than that of juice sterilized at 65°C for 10 min. It was concluded that the sterile filtration by ceramic MF membrane was useful to produce the high quality unheated sterilized apple juice which retained the fresh flavor and color, and it was demonstrated that this method could be used in the commercial production.
