YSG Broth

Glucose is the fermentable carbohydrate providing carbon and energy. Yeast extract is a source of vitamins, particularly the B-group. Soluble starch acts as a growth factor, functioning like a colloid protector, and neutralizes toxic products that form during the development of the organisms. The pH value and the high incubation temperature inhibit the contaminating flora.

Spoilage of shelf-stable fruit juice products by Alicyclobacillus bacteria can be very costly. It is therefore important that concentrates and other raw materials are screened for spores of these taint producers to reduce the risk of spoilage of processed products.

Its presence in packaged products can cause flavour alterations. They do not produce gas or cause any change in the appearance of the beverage container, and therefore the spoilage is discovered only when the consumer opens and begins to consume the product. Fortunately, Alicyclobacillus are not pathogenic bacteria.

Preparation

Suspend 6 grams of the medium in one liter of distilled water. Mix well and dissolve by heating with frequent agitation. Boil for one minute until complete dissolution. Dispense into appropriate containers and sterilize in autoclave at 121 °C for 15 minutes.

Instructions for use

1. Take the inoculum with a sterile loop.
2. Submerge the loop into the medium and shake gently.
3. Incubate at 60 °C for 48-72 hours.

• BAUMGART, J. and MENJE, S.: The Impact of Alicyclobacillus acidoterrestris on the Quality of Juices and Soft Drinks. Fruit Processing 7; 251-254 (2000).
• IFU Working Group Microbiology: First Standard IFU-Method on the Detection of Alicyclobacillus in Fruit Juices. (April 2003)
• Jensen Nancy, Evaluation of detection methods for alicyclobacilli in fruit juice concentrates in Australia. Food Science, Australia.
• Akira Yokota, Tateo Fujii, Keiichi Goto, Alicyclobacillus: Thermophilic Acidophilic Bacilli. Springer (2008).
• Chang SS, Kang DH. Alicyclobacillus spp. in the fruit juice industry: history, characteristics, and current isolation/detection procedures. Washington State University, Pullman, Washington, USA.