Food Safety Magazine

FOOD SAFETY INSIDER | August/September 2010

An Effective Alternative to Bulk Liquid Media Preparation

An Effective Alternative to Bulk Liquid Media Preparation

Food pathogen testing is necessary to guard against releasing a contaminated product that could jeopardize the health of the consumer. Product recalls cost food and ingredient manufacturers millions of dollars each year. Recalls because of contamination will damage a brand’s reputation because of lost consumer confidence. This impact usually extends to products not involved in the recall, but sold by the same manufacturer. The need to test for pathogens is the same for all food, regardless of whether the food is for humans or animals.

ALcontrol Laboratories is one of the largest laboratory service businesses in Europe, with laboratories in the United Kingdom (UK), Benelux and Sweden, offering services covering food, environmental, potable water, land, oil, asbestos and air testing. ALcontrol Food is a UK market leader in food analysis, with six laboratories throughout the UK.

ALcontrol Food laboratories are UK Accreditation Service (UKAS) group accredited to ISO 17025, which gives them substantial capacity and contingency capability should unforeseen circumstances arise. The UK laboratories hold independent supplier audits (ISAs) to facilitate analysis of modeling and simulation (M&S) requirements and UK Department for Environment, Food and Rural Affairs (DEFRA) approval for the animal feed industry. With a fleet of refrigerated vehicles across the network of laboratories, they provide customer sample collection throughout the entire UK. Their industry-leading electronic reporting system (AMIS) provides results as rapidly as methods allow, enabling customers to easily store, manage, report and perform trend analysis of large amounts of data. ALcontrol analyzes a vast range of sample types, from raw meat, raw fish, mechanically recovered meat and mycoprotein to milk, snacks, confectionery, ready meals, sandwiches, herbs and spices. Such a wide range of sample types necessitates a wide range of microbiological tests and methods. Enumeration tests, such as aerobic colony count, E. coli, coliforms and S. aureus, are routinely performed. Some pathogen analyses, such as Salmonella, Listeria monocytogenes, Campylobacter and E. coli O157, aim to determine the presence or absence of the organism. These tests require an enrichment process to ensure detection of even small levels in the product. With approximately 2.2 million samples analyzed each year, it is imperative that processes are as efficient as possible.

Bulk Liquid Handling
Buffered peptone water (BPW) is the main diluent used by ALcontrol in the preparation of samples. Each batch takes time to prepare in terms of weighing out media powder, measuring liquid and autoclaving and cooling bottles, which can take 4 to 5 hours. Staff availability, the number of runs per day and the number of autoclaves available all restrict the production of BPW. As the number of samples increased at the Shrewsbury laboratory (now handling 170,000 tests per month), it was evident that the autoclave capacity for the manufacture of liquid media was becoming a limiting factor. The autoclaves were not coping well with running 24 hours per day, but the installation of further machines was not possible within the timescale required. After considering other ideas, such as prepared media options, Oxoid Dry-Bags™ provided an ideal solution. Following a short trial period, it was clear that they would fit well into current procedures, enabling an increase in media production and efficiency without heavy capital investment.

Easy to Use and Cost Effective
“We are impressed by the Dry-Bags’ ease of use,” says Paul Anderson, site manager at ALcontrol, Shrewsbury. “They fit directly onto automatic diluters for dispensing, thereby reducing the risk of contamination.” As a disposable option, they eliminate the time and expense of recycling glassware associated with in-house media production. They offer cost savings in terms of running the autoclaves (300 L saves 3–4 autoclave runs) and by reducing the number of quality control checks necessary. (The batch numbers of the Dry-Bags change far less than those of in-house BPW, Paul notes.) All these factors lead to more efficient media production. “The performance pressures and wear and tear on the autoclaves is reduced,” continues Paul. “The Dry-Bags stack neatly and tidily into existing laboratory crates and take up far less space than glass bottles. Media staff time is freed up to concentrate on other tasks, and the Dry-Bags have been incorporated into our production without having to make any changes to sample processes.”

Enhanced Flexibility
“Perhaps more importantly, the media can be reconstituted in around 10 minutes, significantly reducing the lead-time of BPW production. This allows us to cope seamlessly with large fluctuations in workload, which are often typical of our business. They enable the laboratories to be highly flexible and respond efficiently to the media demands of variable sample through-put.”

Availability
The Oxoid Dry-Bags are available through the Microbiology Division of Thermo Fisher Scientific. More information can be found at www.remel.com or www.oxoid.com.

www.remel.com