Aims: Indigenous fermented milk products like mishtidoi,
shrikhand, lassi and buttermilk that are famous products of West Bengal,
Maharashtra, Punjab, and Karnataka, respectively. Nowadays, they are available
all over India and are liked by the majority of the human population. These are
fermented products acidic in nature, contain sugar that favours the growth of
molds and thus require refrigeration to increase the shelf life. Prolonged
storage of these products may provide good growth conditions for psychrotrophic
molds which grow at lower temperatures. This may lead to the deterioration of
products by the proteinases and lipases produced by molds and few of the
psychrotrophic molds excrete mycotoxins making the product unsafe for
consumption. With this background, the present study was taken up to find the
types of psychrotrophic molds in Indigenous fermented milk products available
in the Bengaluru market as well as to characterize their nature.
Study Design: In order to study the types of psychrotrophic
molds present in indigenous fermented milk products, unbranded (n=6) and
branded (n=15) samples such as mishtidoi, shrikhand, lassi and buttermilk were
collected from Bangalore markets and subjected to isolation of molds at low
temperature (0-70C) using selective medium and further the isolates obtained
were identified based on their characteristics.
Place and Duration of Study: The research work was conducted
in the Department of Dairy Microbiology, Dairy Science College, Karnataka
Veterinary, Animal and Fisheries Sciences University (KVAFSU), Hebbal,
Bengaluru, 560 024, Karnataka, India between June 2014 to June 2015 as part of
postgraduate research work, Hebbal, Bangalore-24 and literature was updated
recently.
Methodology: The market samples of indigenous fermented
dairy product samples were subjected to pour plating using sterile malt extract
agar adjusted to pH 3.5 and incubated plates at 5oC for 25 days. The mold
isolates obtained were identified by colony morphology, microscopic examination
for cell morphology and specific biochemical tests.
Results: A total of 21 psychrotrophic mold isolates were
obtained from branded and unbranded indigenous fermented milk products. Among
21 psychrotrophic molds, 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 indigenous
fermented dairy product 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 Penicillium
chrysogenum (57.12%), Alternaria alternata (28.56%), Mucor mehei (9.52%) and
Cladosporium cladosporioides (4.76%) at the species level. Except for unbranded
mishitdoi, all types of indigenous fermented dairy product samples were found
to contain psychrotrophic molds.
Conclusion: Penicillium chrysogenum was the most abundant
species found especially in branded butter milk indicating longer refrigeration
may lead to the selection of psychrotrophic molds due to low-temperature
storage and favourable pH (3-5) of the indigenous fermented dairy product
samples. This psychrotrophic mold produced citrinin, a mycotoxin that affects
the liver. Hence care must be taken to avoid consumption of long-stored
refrigerated indigenous fermented products like lassi and buttermilk.
Author(s) Details
Basavabharati
Department of Dairy Microbiology, Dairy Science College, Mahagaon Cross,
KVAFSU, Kalaburagi, 585 316, Karnataka, India.
N. Suchithra
Department of Dairy Microbiology, Dairy Science College, KVAFSU, Hebbal,
Bengaluru, 560 024, Karnataka, India.
R. Prabha
Department of Dairy Microbiology, Dairy Science College, KVAFSU, Hebbal,
Bengaluru, 560 024, Karnataka, India.
Please see the link:- https://doi.org/10.9734/bpi/rpmab/v5/1726
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