Cat. no. C7510 CRITERION™ Orange Serum Agar 87gm
Cat. no. C7511 CRITERION™ Orange Serum Agar 500gm
Cat. no. C7512 CRITERION™ Orange Serum Agar 2kg
Cat. no. C7513 CRITERION™ Orange Serum Agar 10kg
Cat. no. C7514 CRITERION™ Orange Serum Agar 50kg


Hardy Diagnostics CRITERION™ Orange Serum Agar is used for the cultivation and enumeration of aciduric, putrefactive microorganisms which include Lactobacillus spp., Bacillus spp., Leuconostoc spp., Clostridium spp., and yeast and molds in fruit juices and fruit juice concentrates, especially citrus fruits.(5)

This dehydrated culture medium is a raw material intended to be used in the making of prepared media products, which will require further processing, additional ingredients, or supplements.


The microbial population of citrus foods and juices varies greatly depending on how foods are processed and preserved. A small percentage of contaminated fruit can "seed" the operating equipment with spoilage organisms. Equipment that is used for fruit juice preparations is often found to be a significant source of contamination. There are many specific operations, or areas, where microbial buildup can occur such as presses, extractors, finishers, mills, pipelines and conveyors. Geotrichum candidum has been labeled the "machinery mold" because of its tendency to accumulate on fruit processing equipment. Aerobic plate counts can provide an index for assessing the sanitation of citrus fruit and juice processing equipment.(8)

In the production of citrus concentrates, juice may be held in stainless steel tanks for 30 to 120 minutes before high-temperature evaporation. It is during this holding period that the product is most susceptible to microbial spoilage. The spoilage of unpasteurized fruit juices is most often due to aciduric organisms such as lactic acid bacteria and yeast such as Saccharomyces, and Candida spp. being the most commonly isolated spoilage organisms.(8)

Commercially prepared and packaged citrus fruit juices and products have a pH range of 2.9 to 4.0. For example, the pH of orange juice is usually 3.0 to 4.0 and other acidic foods like tomato juice have pH that ranges from of 3.9 to 4.4.(7) Because of the low pH of fruits and fruit juices, aciduric molds and yeast are the microbes that are most often encountered in contaminated citrus products. Of the aciduric bacteria, the lactic acid group, primarily Lactobacillus and Leuconostoc spp., is most often observed.(8) On occasion, C. pasteurianum is responsible for the spoilage of products with low pH such as tomatoes, pears, figs and pineapples.(7) While potential contaminants of food products, pathogenic bacteria are not usually encountered in citrus fruit products due to the low pH and the pasteurization process during manufacturing. However, non-pasteurized apple cider has been reported to be responsible to over 200 cases of salmonellosis. Studies have shown that Salmonella enterica is able to survive up to 30 days in apple juice with a pH of 3.6.(8)

Foodborne yeasts and molds include several hundred species. These organisms, due to their wide range of pH and temperature tolerances, as well as their assortment of hydrolytic enzymes, have the ability to grow in most low pH food. Contamination of foods by yeast and molds result in substantial losses to the producer, processor and the consumer. Several of the foodborne molds, and possibly yeast, may be hazardous to human and animal health due to their ability to produce mycotoxins. Yeast and molds may also elicit allergic reactions or infections in those individuals who are aged or those receiving chemotherapy or antibiotics.(7)

Orange Serum Agar is specially formulated for the isolation, cultivation and enumeration of the aciduric bacteria, mold and yeasts seen in citrus foods, juices and other foods with low pH values. Orange Serum Agar contains: casein peptone as a nitrogen source, yeast extract to provide B-complex vitamins to stimulate growth, and dextrose as a carbohydrate source. In order to create an acidic media that favors the recovery of aciduric organisms, orange powder is added to the media, while potassium phosphate serves as a buffer.


Gram weight per liter: 43.7gm/L
Casein Peptone 15.5gm
Dextrose 4.0gm
Orange Powder 3.5gm
Yeast Extract 3.0gm
Dipotassium Phosphate 2.5gm
Agar 15.2gm

Final pH 5.5 +/- 0.2 at 25ºC.

* Adjusted and/or supplemented as required to meet performance criteria.


Store the sealed bottle(s) containing dehydrated culture medium at 2-8ºC. Dehydrated culture medium is very hygroscopic. Keep lid tightly sealed. Protect dehydrated culture media from moisture and light. The dehydrated culture media should be discarded if it is not free-flowing or if the color has changed from its original light tan.

Store the prepared culture media at 2-8ºC.



1. Suspend 43.7gm of the dehydrated culture media in 1 liter of distilled or deionized water. Stir to mix thoroughly.

2. Heat to boiling to dissolve completely.

3. Sterilize in the autoclave at 121ºC. for 15 minutes.

4. Cool to 45-50ºC.

5. Aseptically dispense as into sterile petri dishes.


For information on procedures and interpretation of results, consult listed references or refer to the prepared media Instructions for Use (IFU) for Cat. No. G91.



Standard microbiological supplies and equipment such as autoclaves, incinerators, and incubators, etc., are not provided.


Test Organisms Inoculation Method* Incubation Results
Time Temperature Atmosphere
Lactobacillus acidophilus
ATCC® 4356
J 1-5 days 35°C Aerobic Growth; 10-100 colonies
Leuconostoc paramesenteroides
ATCC® 33313
J 1-5 days 35°C Aerobic Growth; 10-100 colonies
Aspergillus brasiliensis
ATCC® 16404
J 1-5 days 35°C Aerobic Growth; 10-100 colonies

User Quality Control


CRITERION™ Orange Serum Agar powder should appear homogeneous, free-flowing, and light tan in color. The prepared media should appear slightly opalescent and light to medium amber in color.


1. Anderson, N.L., et al. Cumitech 3B; Quality Systems in the Clinical Microbiology Laboratory, Coordinating ed., A.S. Weissfeld. American Society for Microbiology, Washington, D.C.

2. Jorgensen., et al. Manual of Clinical Microbiology, American Society for Microbiology, Washington, D.C.

3. Tille, P., et al. Bailey and Scott's Diagnostic Microbiology, C.V. Mosby Company, St. Louis, MO.

4. Isenberg, H.D. Clinical Microbiology Procedures Handbook, Vol. I, II & III. American Society for Microbiology, Washington, D.C.

5. MacFaddin, J.F. 1985. Media for Isolation, Cultivation, Identification, Maintenance of Bacteria, Vol. I. Williams & Wilkins, Baltimore, MD.

6. Quality Assurance for Commercially Prepared Microbiological Culture Media, M22. Clinical and Laboratory Standards Institute (CLSI - formerly NCCLS), Wayne, PA.

7. Landry, W.L., Schwab, M.J., Lancette, G.A. 1995. Bacteriology Analytical Manual, 8th ed. AOAC International, Gaithersburg, MD.

8. Vanderzant, C. and Splittstoesser, D.F. 1992. Compendium of Methods for the Microbiological Examination of Foods. American Public Health Association, Washington, D.C.

ATCC is a registered trademark of the American Type Culture Collection.