BAM! Seward unveils lab blender for large volume food testing

The Stomacher 4500 provides laboratories with a blender capable of homogenising sample volumes from 1000 to 4500mL.

In the FDA’s BAM​, 375g composite samples are required for microbiological analyses of food.

Reduce analysis costs ​

Dan Crothers, managing director at Seward, said the machine was launched in response to increased market demand for sample preparation methods suitable for larger volume composite samples.

“While not suitable for all types of testing protocols, multiple composite samples can provide improved sampling precision and reduce the total number of analyses required compared to non-composite sampling,” ​he told FoodQualityNews.

“This strategy can be used as a method to reduce analysis costs when such costs are large relative to sampling costs.”​

The Stomacher 4500 has programmable settings for preparation protocol for microbial extraction, depending on the food sample under analysis. 

The blender is controlled through blending time and speed settings.

Most food testing protocols require blending time for 30-60 seconds at 230 RPM but it will depend on guidelines and testing protocols by the laboratory, said Seward.

Food sample category types​

The Stomacher 4500 is for extraction from 375g composite samples for the preparation of Category III food samples for Salmonella detection. 

The composite sample should be combined with its pre-enrichment medium at a 1:9 sample-to-broth ratio (375g sample/3375mL pre-enrichment) with no risk of spillage.

The large volume Stomacher enables food manufacturers to combine 15 x 25g (375g) analytical units, rather than testing each individually, so saving time when analysing lower risk food products.

Crothers said some laboratory testing protocols provide the option for individual sub-samples to be analysed separately or representative composite samples to be taken.

“While most food testing labs are familiar with the Stomacher 400 for 25g samples, the Stomacher 4500 provides the option for larger composite sampling to be processed thereby increasing the productivity of the lab,” ​he said.

“Many laboratories already use the Stomacher 3500 for large volume testing up to 3500ml. Our market research also suggests many labs used manual blending processes such has mixing in jars or kneading by hand in a Stomacher bag. ​

“While these methods are readily accessible, it is difficult to retain blending reproducibility across samples.”​

A 25g sample/225mL pre-enrichment BAM protocol remains for higher risk Category I and Category II foods, which would not normally go through a process lethal to Salmonellabetween sampling and consumption.

For this, food testing labs could use the Stomacher 400 Circulator, said Seward.

USDA MLG 5.04 Detection, Isolation and Identification of E.coliO157:H7 from meat products requires random collection of five sub-samples to make a 325g composite sample which is then blended in a Stomacher.