Membrane filtration method for enumeration and isolation of Alicyclobacillus spp. from apple juice

Abstract

Aim: To evaluate the applicability of filtration membranes for detecting Alicyclobacillus spp. spores in apple juice. Methods and Results: Ten types of nitrocellulose membrane filters from five manufacturers were used to collect and enumerate five Alicyclobacillus spore isolates and results were compared to conventional K agar plating. Spore recovery differed among filters with an average recovery rate of 126·2%. Recovery levels also differed among spore isolates. Although significant difference (P < 0·05) in spore sizes existed, no correlation could be determined between spore size and membrane filter recovery rate. Conclusions: Recovery of spores using membrane filtration is dependent on the manufacturer and filter pore size. Correlations between spore recovery rate and spore size could not be determined. Significance and Impact of the Study: Low numbers of Alicyclobacillus spores in juice can be effectively detected using membrane filtration although recovery rate differences exist among different manufacturers. Use of membrane filtration is a simple, fast alternative to the week‐long enrichment procedures currently employed in most quality assurance tests.

Electronic nose and Alicyclobacillus spp. spoilage of fruit juices: An emerging diagnostic tool

“…counting from juices was troublesome at the tested concentrations. In literature bacterial enumeration at low concentrations is reported as imprecise and difficult (Duvenage, 2006;Lee, Chang, Shin, & Kang, 2007). Consequently, in peach and orange juices, it can only be stated that EOS 835 was able to detect contamination in samples inoculated 24 h earlier with as little as 10 and <10 2 c.f.u./ml respectively.…”

Recovery of Alicyclobacillus from Inhibitory Fruit Juice Concentrates

“…Some loss of spores through filtration is not unusual. Lee et al (11) found that recovery of Alicyclobacillus varied greatly among filter brands and pore sizes.…”

Optimisation of a direct plating method for the detection and enumeration of Alicyclobacillus acidoterrestris spores

“…The composition and structure of the membrane specific to the manufacturer may also affect the efficiency of spore recovery of spores. Lee et al (2007) reported that membranes with the same pore size but from different manufacturers produced significantly different results. Membrane filtration is also not suitable for all products, e.g., dense fruit juice concentrates and liquids that are not clear (Jensen, 1999).…”

“…Nevertheless, the membrane filtration method has some disadvantages. Lee et al (2007) investigated the use of different filtration membranes for the recovery of Alicyclobacillus spores in apple juice. The application of filtration membranes with two different pore sizes (0.22 and 0.45 μm) obtained from five manufacturers was evaluated and compared with conventional spread plating on K agar.…”

“…The use of SK agar for the recovery of Alicyclobacillus has been reported only by Chang and Kang (2005) to date. Additionally, there are few published studies investigating the application of membrane filtration techniques for the enumeration of Alicyclobacillus spores (Lee et al, 2007;Pettipher and Osmundson, 2000;.…”