If cheesemaking is an art, then starter cultures can be likened to the temperamen tal artist, says Dan Pelgrin of Madison, Wis.-based Rhodia, Inc., a manufacturer of microbiological starter cultures for the food, dairy and agriculture industries. As production manager for dairy-related products at Rhodia, Pelgrin knows that special attention must be paid to factors such as time, temperature and blending to ensure that highly sensitive cheese starter cultures are exactly as required.

In cheesemaking, these strains of bacteria are used to turn milk into solid or added to solidified curds to alter the product's final taste and texture.

At Rhodia, the manufacture of cultures begins with the blending of raw materials. The mixture is then sterilized and sent on to a fermenter vessel, where it is inoculated with a select strain of bacteria to begin fermentation.

The goal of fermentation is to grow out cells to a certain point, after which cooling is applied to slow cell metabolism and prevent the build-up of toxins. To that end, Rhodia employs a heavy-duty positive rotary displacement pump -- the Tri-Clover TSR 7 -- to achieve rapid, but uniform and gentle cooling. Once the target temperature is reached, the mixture is ready for harvest.

According to Pelgrin, the displacement pump has helped to dramatically reduce cooling time.

Rhodia employees believe that the old, slower process inhibited production. The reason is that cell destruction occurs if the cooling process is prolonged and part of the batch continues to metabolize.

Tri-Clover Inc., 9201 Wilmot Rd., Kenosha, WI 53141-1413. Tel: 414-694-5511.