This medium is recommended for cultivation and enumeration of microorganisms associated with spoilage of citrus products, cultivation of lactobacilli and other aciduric organisms and pathogenic fungi. The lactic acid bacteria include Lactobacillus fermentum, L.plantarum, and Leuconostoc mesenteroides. Orange Serum Agar is recommended by APHA. Orange serum provides an optimal environment for the recovery of acid tolerant microorganisms from citrus fruit products.