2.2.1. Cleaning procedure
To guarantee the sterilization condition of the UHPH and UHT processes, all processing circuit was submitted to a cleaning procedure.
UHT system was sterilized by means of superheated water in all
process circuit at 136 °C for 45 min prior to treatment. After treatment,
the equipment was cleaned following the CIP procedure (cleaning-in-place). First of all, it was passed through UHT circuit alkaline solution
(3% NaOH) at 95 °C for 30 min and acid solution (2% HNO3) at
45–50 °C for 20 min. Finally, a disinfecting solution (0.3%) prepared
with acetic and peracetic acids and hydrogen peroxide was used.
UHPH system was sterilized by means of vapor at 140 °C for 50 min
in all circuit process prior to treatment. After soymilk processing, the
equipment was cleaned by using silicate alkaline detergent solution at
70 °C for 30 min followed by nitric acid solution at 45–50 °C for
20 min only through the heat exchangers. Finally the same disinfecting
solution of UHT procedure was applied.
Aseptic tank was sterilized at 130 °C (minimum temperature) for 50 min prior to use by UHPH and UHT treatments. After that, the cleaning procedure was that used by UHT system.