Cleaning and sanitization method for a pilot-scale ultra-shear equipment for liquid food processing

Ultra-shear technology (UST) is a hybrid thermal-nonthermal, semi-continuous high-pressure food processing method. This study aims to develop and validate a clean-in-place (CIP) procedure for pilot-scale UST equipment. The CIP procedure for UST equipment involves rinsing with water (≈60 °C, 14 min), applying an alkaline wash (Alconox, 1% w/v, 43 °C, 10 min), followed by another water rinse (≈60 °C, 14 min), an acid wash (peracetic acid, 0.25% w/v, 42 °C, 10 min), a disinfectant wash (hydrogen peroxide, 0.3% w/v, 39 °C, 10 min), and a final water rinse (≈60 °C, 14 min). Processing pressure during CIP was 138 MPa. Listeria innocua ATCC33090 cells (6.3 ± 0.1 log CFU/mL) and Clostridium sporogenes PA3679 spores (4.3 ± 0.2 log CFU/mL) suspended in a pressure-stable buffer solution were processed with two different pressure-thermal UST conditions to evaluate sanitation efficiency. It was further verified using representative liquid foods (raw milk, dairy-plant protein dispersions, and ice cream mix). Three critical microbial testing points were used for sampling after UST treatments, with or without CIP. Surviving cells and spores were enumerated using suitable agar growth media. Results showed that the tested CIP procedure successfully reduced L. innocua (5.0, 3.7, and 3.1 log CFU/cm2) and C. sporogenes spores (2.5, 1.1, and 0.7 log CFU/cm2) populations at different testing locations below the detection limit. The application of the developed sanitation procedures after UST processing of representative food matrices also effectively sanitized the equipment. However, residual food deposits at the bottom of the bladder within the pressure vessel required manual removal, which is a limitation of the current method. These findings will be useful for food processors interested in developing sanitation procedures for industrial-scale UST equipment. •Clean-in-place (CIP) procedure for a pilot ultra-shear equipment was evaluated.•CIP procedure reduced Listeria innocua population by ≥ 3.1 ‒ ≥ 5.0 log CFU/cm2.•CIP procedure reduced Clostridium sporogenes spores by ≥ 0.7 ‒ ≥ 2.5 log CFU/cm2.•Developed CIP procedure can sanitize ultra-shear equipment.