Laboratory mixer: differences between paddle blender and blender

Making an analysis and quality control requires a flexible and user-friendly equipment in order to prepare samples efficiently. In this way, different methods have come up, such as laboratory mixers.

These are suitable for intense mixing, dispersing, homogenizing, emulsifying or mincing operations for cuttable materials. Simple handling, high user safety and efficiency are just some of the many advantages that these mixers can offer.

Laboratory mixers depending on homogenizors methods

Here we have compared different laboratory mixers based on homogenizors methods.

Paddle blender, a high quality homogenizer

The pounding of the sample by the steel paddles removes bacteria from the food particles, partly by violent shearing forces as the liquid moves from side to side, and partly by the actual compression of the sample itself as it becomes trapped under the paddles.

Microbiological examination of various foods

indicates that the paddle blender releases a significantly large number of viable microorganisms that are calculated on the basis of colony count than other methods of homogenization, except samples of cheese and powdered egg and milk.

Advantages and disadvantages of a paddle blender

On the one hand, some of the main advantages of paddle blender are:

• The Masticator produces low heat.
• The paddle blender uses disposable polythene bags for homogenization, so the laboratory mixer doesn’t need washing up or sterilization, except for the spoons used to distribute the sample into a count and enrichment jars.
• It doesn’t require a lot of maintenance.
• It’s suitable for large volumes.

On the other hand, the disadvantages that you can find using a paddle blender are:

• Special bags, already sterilized, need to be used.
• On some occasions, bags break in the machine. Sometimes, this is due to sharp contours, however, the user can utilize more than one bag to reduce the risk.
• Several types of plastic bags have been designed to improve the dispensing of the contents of the plastic bags after homogenization.

For some, this is the best method to homogenize samples although it needs a specific material and more maintenance than other methods.

Laboratory blender without consumables

With the use of a laboratory blender, we don’t need consumables, however, the bacteria count can be reduced by the heat that is generated by the blender. Furthermore, higher levels of heat are achieved when high speeds are maintained for a long time and the sample is not diluted.

Besides this, the blender must be washed and sterilized each time it is used and the blender washers need to be changed after each use to avoid leakages. This, together with labor costs, involves an expense, particularly where many blenders are used non-stop.

Speedmill for on-site processing samples

SpeedMill is a small portable milling machine, suitable for on-site sample processing and easily adaptable to different sample types.

Some of the advantages of using this method are: it is portable and can be adapted to different matrices. However, it has some disadvantages such as sonication treatment leding to a decrease in pathogen recovery compared to CFU counts obtained after an initial rinse and vortexing step. Besides, it is not suitable for high volumes and the low-volume SpeedMill enabled intermediate extraction success. 

Sonication, one of the oldest methods

Sonication is a rather old but simple method that exerts a distinct kind of mechanical force compared to stomaching or milling. The instrument doesn’t need to be washed and sterilized each time it is used. Being this it’s the biggest advantage, it has some disadvantages that we must take into account.

First of all, the bacteria count can be reduced by the heat generated by the blender. Besides, sonication treatment led to a decrease in pathogen recovery compared to the CFU cunts obtained after an initial rinse and vortexing step. 

Another weaknesswould be that the sonication doesn’t break up the matrix so it’s not efficient for the detection of inn-matrix contamination. In addition, it is not portable.