Characterization of Psychrotrophic Molds from Indigenous Fermented Dairy Products

Aim: The aim of the study was to establish the number and type of psychrotrophic molds in Indigenous Fermented Dairy Products (IFDP) of Bengaluru market, Karnataka, India.

Methodology: The study was taken up in the Department of Dairy Microbiology, Dairy Science College, KVAFSU, Hebbal, Bengaluru, 560 024, Karnataka, India between June 2014 to June 2015 as part of post graduate research work. The samples used in the study were unbranded (n=6) and branded (n=15) IFDP such as Mishtidoi, Shrikhand, Lassi and Buttermilk collected from Bengaluru markets. The market samples of IFDP were subjected for isolation on poured sterile malt extract agar of pH 3.5. The isolates were obtained by pour-plate technique on malt extract agar (pH 3.5). The mold isolates were identified by colony morphology, microscopic examination for cell morphology and specific biochemical tests.

Results: Out of total of 21 psychrotrophic mold isolates, 6 and 15 isolates were obtained from unbranded and branded samples, respectively. Based on the preliminary identification, the isolates were characterized as Penicillium spp. (n=3), Mucor spp. (n=2) and Cladosporium spp. (n=1) from unbranded samples while branded IFDP samples showed Penicillium spp. (n=9 and Alternaria spp. (n=6) were isolated from branded samples. According to pheno and genotypic characterization, the isolates were identified as P. chrysogenum(57.12%) followed by A. alternata (28.56%), C. cladosporioides (4.76%) and M. mehei (9.52%) at the species level.

Conclusion: Except unbranded mishitdoi, all types of IFDP samples were found to contain psychrotrophic molds. P. chrysogenum was the most abundant species especially in branded butter milk indicating longer refrigeration may lead to selection of psychrotrophic molds due to low temperature storage and pH of the IFDP samples.