Читать книгу Analytical Food Microbiology - Ahmed E. Yousef - Страница 34

Most test samples require homogenization before analysis. The goal of homogenization is to release microorganisms from food into suspension. Blenders, stomachers, sonicators, shakers, and hand massaging of bagged food are different approaches for homogenizing a food sample. Liquid food samples are manually mixed before analysis, whereas solid foods commonly require mechanical stirring (homogenization) in a suitable diluent to break food clumps and release microorganisms from the food matrix. Methods of homogenization may vary in ability to recover entrapped microorganisms. Blenders and stomachers (Figure 2.2) are commonly used homogenizers to prepare the food sample for analysis. The revolving blades of the blender divide the food into small particles and mix them with the diluent. The same goal may be achieved using a stomacher, depending on the characteristics of the food. The stomacher is a mechanical device that agitates a food sample placed in sterile plastic bag. The back and forth mechanical action of the stomacher paddles mimics the stomach action (hence the name) and helps incorporate the sample particles into the diluent.

Figure 2.2 Food blender (left) and stomacher (right).