Efficacy of Sanitizers to Bacillus cereus Biofilm on Food Contact Surfaces

Introduction: Biofilms in which the spore-forming Bacillus cereus readily forms on various types of food contact surfaces are resistant to sanitizers. The effectiveness of sanitizers for B. cereus biofilms depends on the surface material and the condition with regards to whether a scratch exists or not.

Purpose: This study was conducted to compare the 4 sanitizers’ effectiveness against B. cereus biofilms on 5 different surface materials and surface conditions such as being scratched or non-scratched.

Methods: Five coupons (glass, GL; stainless steel, SUS; polyethylene, PE; wood) were made to 10 (2 by 5) cm² and were prepared as either scratched or non-scratched. All coupons were immersed in spore suspensions (27°C for 4h) and were incubated in the RH 100% tube to form biofilms (27°C for 4 days). Each coupon on the biofilms was treated with chlorine (Cl), chlorine dioxide (ClO₂), quaternary ammonium compound (QAC), and alcohol of 70% solution (Cl, ClO₂, QAC, 200ppm).

Results: The SUS indicated the lowest rate of adherence (6.81 ± 0.05 log CFU/10 cm²). The wood showed lowest effects of sterilization for all conditions. Cl was proven to be the most effective for controlling B. cereus biofilms on most of the coupons. Sterilization efficacy on the scratched SUS was lower than the non-scratched SUS by 5.95 ± 1.13 and 5.57 ± 0.21 log CFU/10 cm², respectively (P < 0.05).

Significance: The types of surface materials should be considered when making purchases by food service operations. In addition, a guideline for the prevention of scratches on the surface food materials and the concentration levels of sanitizers based on the condition of scratched materials is necessary.