ATP-Bioluminescence as a method to evaluated microbiological quality of UHT milk

Abstract

New approaches are needed to quickly indicate possible contamination of UHT milk, among them the technique of ATP-Bioluminescence. Therefore, the aim of this study was to compare the results of culture methods with the results of ATP-Bioluminescence technique of 102 UHT whole milk samples incubated at 48, 72, and 168 hours. UHT milk samples were analyzed for the presence of mesophilic and psychrotrophic aerobic microorganisms using Plate Count Agar (PCA), Brain-Heart Infusion (BHI) media and Petrifilm TM Aerobic Count (AC) plates. The ATP-Bioluminescence technique was applied through the Microbial Luminescent Screening (MLS) system. Significant correlations were found between counts of aerobic mesophilic microorganisms on PCA, Petrifilm TM AC, BHI and results of ATP bioluminescence technique (P≤0.05). The ATP-Bioluminescence technique had higher correlation with counting method in PCA than BHI media. At lower pass/fail limits of Relative Light Units (60, 50, 45 and 40 RLU), the number of samples identified as positive increased and statistically agreed with aerobic mesophilic microorganism counts (P>0.05). For the dairy industry, the ATP-Bioluminescence technique may become an important tool that assists the official methods to quickly monitor the microbiological quality of UHT milk though this will likely require a threshold below 150 RLU.Keywords: ATP-Bioluminescence, microbiology, milk, quality, UHT RESUMO Novos métodos são necessários para detectar de forma rápida a contaminação do leite UAT, entre eles, a técnica de ATP-Bioluminescência. Portanto, objetivou-se comparar os resultados de métodos de cultura tradicionais com os resultados de ATP-Bioluminescência de 102 amostras de leite UAT integral incubadas por 48, 72 e 168 horas. Os leites UAT foram analisados quanto à presença de microorganismos aeróbicos mesófilos e psicrotróficos usando os ágares PCA, BHI e placas Petrifilm TM AC. A técnica de ATP-Bioluminescência foi aplicada por meio do sistema Microbial Luminescent Screening (MLS). Significantes correlações foram obtidas entre as contagens de micro-organismos mesófilos

Rapid detection of microbial contamination in UHT milk: practical application in dairy industry

“…The pre-incubation step had to be included also in ATP bioluminescence methods. The Cunha et al (2014) found a strong correlation between TBC and an ATP bioluminescence method after 48 h of preincubation of UHT milk samples. But in our study, we found that 48 h of UHT milk pre-incubation (at 30°C) containing a low concentration of spore-forming bacteria (< 10 CFU/l) is insufficient (Table 3).…”