Orange Serum Agar (OSA)
CAT No.: AS-1312 | Pack sizes: 500 g, 6 * 500 g
 
Description
Orange Serum Agar (OSA) is a selective medium developed for the isolation, cultivation, and enumeration of aciduric microorganisms, particularly those associated with the spoilage of fruit juices, soft drinks, and acidic food products. It supports the growth of yeasts, molds, and acid-tolerant bacteria such as Lactobacillus, Leuconostoc, and Acetobacter species.
This medium is commonly used in the food and beverage industry, including wineries, breweries, and juice processing facilities, to detect spoilage organisms that thrive in low-pH environments.
Principle
OSA combines peptones, yeast extract, and dextrose to provide essential nutrients for microbial growth. Orange serum solids supply natural acids and carbon sources, adjusting the medium’s pH to ~5.5 and enhancing selectivity for aciduric organisms. The low pH and composition suppress many non-aciduric bacteria while allowing robust recovery of targeted spoilage microbes.
 
Typical Composition (per litre)
Casein enzymic hydrolysate (Peptone): 10.0 g
Yeast Extract: 3.0 g
Dextrose: 4.0 g
Dipotassium hydrogen phosphate: 3.0 g
Orange Extract: 5.0 
Agar: 17.0 g
Final pH (25 °C): 5.5 ± 0.2
 
Applications
Detection of aciduric spoilage organisms in fruit juices, ciders, wines, and soft drinks
Quality control of acidic beverages and concentrates
Enumeration of lactic acid bacteria and acetic acid bacteria in fermentation processes
Routine QC testing in beverage production facilities
 
Storage & Shelf Life
Store tightly sealed in a cool, dry place (4-8 °C), protected from moisture and light.
 
Shelf life: 36 months from the date of manufacture, unopened.
 
Pack sizes available: 500 g | 6 * 500 g
 
Brand: Ausamics Life Science Pty Ltd – Melbourne, Australia
📧 sales@ausamics.com | ☎ +61 412 520 598