HLP comes as a powder and you mix 7 grams for every 100 mL of distilled water. You’ll want to check the Safety Data Sheet before working with it as it contains Cycloheximide, which is toxic, to inhibit yeast growth. I work in a chemical fume hood while using it. You will need a constant temperature of 28-30☌ to incubate your samples but since it’s a semisolid media it forms an anaerobic environment in the test tube when mixed.įor safety you’ll want a respirator, face shield and gloves. Many breweries start out using HLP since you don’t need an autoclave or anaerobic incubator or chamber to use it.

Lactobacillus will form rods and Pediococcus cocci or spheres. You will need a microscope with a 100X objective to see the stain and cell morphology. It is used to split bacteria into two broad classifications (positive or negative) based on the cell wall. Gram positive bacteria will stain purple when exposed to a series of dyes and a de-colorant during a Gram stain. Lactobacillus and Pediococcus are both Gram positive lactic acid bacteria and if present can sour your beer, produce diacetyl, and affect the mouth feel. Unfortunately some types of bacteria can make for a very unpleasant drinking experience. Luckily, no pathogens are known to exist in beer. You’ll know the difference when you’ve had a well made beer intentionally soured and one that is infected. Eventually you will want a variety of general culture and wild yeast media since the only thing you can count on is the unpredictability of unwanted microbes.Įnjoy drinking sour, ropy, buttery beer? Maybe the sour, but I’ll pass on the other two. Lactobacillus and Pediococcus are the two most common beer spoilers, so if you’re just getting into micro testing in your brewery, it’s a good one to start with. Hsu Lactobacillus Pediococcus is a selective media that supports the growth of Lactobacillus and Pediococcus. Let’s back up a bit before I get too far ahead of myself. What I mean by “read micro” is that I look at the HLP ( Hsu Lactobacillus Pediococcus) tubes I have incubating and see if anything has grown. After I go through the schedule, plan out my day, and determine what samples I need to collect, I read micro. Last month we talked about deciding what samples need to be collected for the day.

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