A Multipurpose Fruit and Vegetable Processing System for Advanced Life Support

During the one-year no-cost extension, we completed the fabrication of the multipurpose fruit and vegetable food processor (MFVP) and the remaining trials with its components. In addition, we conducted a comprehensive study to obtain data on using electrolyzed water for cleaning-in-place (CIP) of the MFVP. CIP with electrolyzed water is an attractive option for cleaning as it does not require detergents (caustic solution) or disinfectants (chlorine). Therefore it could be more suitable for application in a controlled environment system. Electrolyzed water is generated from salt mixed in water. We conducted trials with a stainless steel test-bed containing various components used in the MFVP. The cleaning and disinfection of the components after inoculation was validated with microbial testing. Specifically, the effectiveness of electrolyzed oxidizing water (EOW) and electrolyzed reducing water (ERW) used in clean-in-place (CIP) applications for MFVP were studied using 38 mm (1.5 in) diameter stainless steel (SS316L) pipes fouled with apple juice. Data were compared with industrial CIP cleaner (chlorinated NaOH) and antimicrobial solution (mixture of peroxyacetic acid and hydrogen peroxide). Cleanliness of stainless steel (SS) pipe surfaces was quantified by a hygiene monitoring test and aerobic plate count. Data were obtained to determine the removal of organic debris and microorganisms at 5, 10, 15, and 20 min washing using electrolyzed water and industrial cleaning chemicals. Electrolyzed water showed potential use in CIP applications--it is easy to use and less hazardous compared to the industrial cleaning chemicals. Microbiological evaluation showed 5 min cleaning with EOW followed by 5 min cleaning with ERW was sufficient to drop cell levels from 5.2±0.3 log CFU (colony forming units)/stainless steel chip to below the limit of detection (<0.69 log CFU/cm2). In contrast, in case of bioluminescence tests, there were detectable adenosine triphosphate (ATP) even after 15 min of cleaning, even though the system was microbiologically at below detection. Furthermore, bioluminescence tests revealed that industrial cleaning chemicals were faster in cleaning compared to electrolyzed water. Electrolyzed water needs to be circulated more than 20 min at 0.6 m/s (2 ft/s) flow velocity to achieve acceptable cleaning, whereas industrial cleaning takes only 5 min of circulation for acceptable cleaning based on the bioluminescence readings.