Va-YSG Medium
Va-YSG Medium is optimized for use with the Guaiacol Detection Kit (KYO-08921). Containing yeast extract (for vitamins and growth factors), glucose (as an energy source), soluble starch (for detoxification of metabolic by products) and vanillic acid, this low pH medium promotes Alicyclobacilli growth from fruit juices and facilitates their production of guaiacol.
Alicyclobacillus acidoterrestris, first isolated from soil, is a gram-positive, spore-forming bacillus that briefly gained notoriety after a publicized 1984 incident of apple juice turbidity. Resistance to high heat and acidic environments allows this thermo-acidophilic bacillus (TAB) to withstand fruit washing and juice thermal processing, to grow and spoil acidic foods with production of the pungent compound 2-methoxyphenol (guaiacol), 2,6-dibromophenol, and 2,6-dichlorophenol. [1, 2, 3].
Due to their production of guaiacol, TAB are a constant and significant threat to quality degradation in the production of juices and other products where flavor and odor are important. Even without the distracting flavor problem, product quality may be degraded by slight deterioration during distribution.
TAB contamination is difficult to avoid. Fortunately, A. acidocaldarius and other species that cause contamination are known to be harmless, and the costly spoilage threat posed by TAB can be minimized by vigilantly monitoring for A. acidoterrestris contamination. Given the frequent occurrence of fruit juice deterioration incidents in Europe and other regions, Japan Fruit Juice Association developed and publicized a unified test method for TAB in March 2003 [4]. To promote easy performance of this test, we developed a kit that detects A. acidoterrestris directly in terms of guaiacol production.
Kit Components
YSG Agar Plate 20 plates (Cat. No. KYO-06810)
YSG agar medium for TAB isolation 10 x 2 plates/1 box
Va-YSG Medium (2mL) 100 tubes (Cat. No. KYO-08901)
Vanillic acid added YSG medium for guaiacol formation 2 mL x 100 tubes
Guaiacol Detection Kit 100 tests (Cat. No. KYO-08921)
Reagent 1: 50mM Potassium Hydrogen Phthalate Buffer 60 mL x 2 bottles
Reagent 2: 1.3 % Hydrogen Peroxide Solution 2.5 mL x 1 tube
Reagent 3: Peroxidase-Phosphoric Acid Buffer 2.5 mL x 1 tube
Positive Control: Guaiacol (1050 ppm) 2.5 mL x 1 tube