Research – Biofilm‐forming ability of Alicyclobacillus spp. isolates from orange juice concentrate processing plant

The objective of this study was to evaluate the biofilm‐forming ability of Alicyclobacillus spp. isolates. Biofilm formation was evaluated under a stainless steel surface using orange juice as a culture medium at different temperatures (28 and 45  °C, 30 and 45  °C, and 45 and 60  °C) and contact times (24, 72, and 120 hr). The degree of hydrophobicity and the survival time of the different isolates on the abiotic surface were also investigated. Five Alicyclobacillus spp. isolates from the orange juice industry and a reference strain of Alicyclobacillus acidoterrestris 0244^T were used. The biofilm formation of Alicyclobacillus was observed from 24 hr of contact in at least one temperature tested, as a function of the different incubation times and temperatures. Alicyclobacillus spp. presented variations in the degree of hydrophobicity. Surprisingly, two biofilm‐forming isolates (CCT 7230 and CCT 7346) were hydrophilic, with hydrophobicity index <20%, therefore, they are not necessarily related to cell hydrophobicity and adherence of Alicyclobacillus to the stainless steel surface. This study demonstrated that Alicycclobacillus spp. isolates from the industry can survive the processing conditions and form biofilms on contact surfaces.

Practical applications

Alicyclobacillus spp. may be present in the orange juice industry and form biofilms. In addition, it is known that the equipment is exposed to a wide temperature range for different periods of time and that poorly sanitized stainless steel equipment and surface can provide substrates for the formation of biofilms by Alicyclobacillus spp. Therefore, it is of the most importance to understand how these factors influence the adhesion and formation of Alicyclobacillus spp. in the processing of orange juice.