Effect of acmella pod extracts on controlling microbes present on dairy processing surfaces

Abstract

Identification of microorganisms in dairy processing surfaces (DPS) is important in controlling safety of the finished products. Hence, this study was conducted to identify and control bacteria on stainless-steel (SS) DPS using Acmella (Acmella oleracea L.) flower pod water extract. Three SS (ALSI 304) food processing surfaces were contacted with fresh pasteurized milk for 2 hours, and then the surfaces were rinsed with fresh water. Two of the surfaces were sanitized with Acmella extract and a commercial sanitizer (positive control) separately while keeping the remaining one untreated as the negative control. Swab samples were collected using 100cm² template after 2, 4, 8, 12, 24 and 48-hour time periods, and the total plate counts were obtained using the plate count agar media. All the test surfaces were kept undisturbed at ambient condition (28- 30⁰C RT, 75-80% RH) for 48 hrs. Further, the samples taken from the inoculated surfaces after two hours were subjected to Gram staining and VITEK 2 analyzer for microbial identification. The results revealed that there were 2.31, 1.39 and 5.59 Log CFU/100cm² of bacterial counts in the Acmella treated, positive control and negative control surfaces, respectively after 12 hours, where the initial population was 3.35 Log CFU/100cm² . The reduction of microbial growth in Acmella treated surface was not significantly different (p>0.05) to the reduction observed in positive control, but differed significantly from the negative control (p<0.05). Moreover, there was a significant difference (p<0.05) of 5.52 LogCFU/100cm² microbial density between Acmella sprayed and the negative control surfaces at 48-hour. Further, there were six gram- positive and one gram-negative isolates identified on SS of DPS namely Pseudomonas fluorescens, Staphylococcus warneri, Staphylococcus pasteuri, Staphylococcus haemolyticus, Bacillus circulans, Microbacterium lacticum and Paenibacillus odorifer. Hence, Acmella pod extract can be used as an effective alternative for commercial sanitizers in suppressing the growth of microorganisms on DPSs.