Assiut university researches
Control of Bacterial Biofilm in Feta heese
PLANT IN Upper Egypt
‫ال تح كم ف ى ال ف ي لم ال ح يوى ال ب ك ت يرى ف ى م ص نع‬
.‫إلن تاج ال ج بن ال ف ي تا ب ص ع يد م صر‬
Usama Ghareeb AWAAD Abd-Allah
‫أ سامة غري ب عوض ع بد هللا‬
Mohammed saad Sabreen, Enas El-Prince Mohammed
‫ إي ناس ال برن س محمد‬،‫محمد س عد ص بري ن‬
Abstract:
A total of 576 samples were collected from Feta cheese plant
before and after application of optimized CIP. Raw milk
during all processing step (288), uf Feta cheese samples at
zero time of storage (48) and milk contact surfaces of units of
plant (240). The microbiological examination include B.cereus
, pseudomonas, enterococci and total anaerobic counts. (I)
Microbiological examination of raw milk during manufacture
process before application of optimized CIP: Microbiological
examination of raw milk showed that, the average counts/ml
of B.cereus, pseudomonas, enterococci and total anaerobic
were 3.7x104, 5x105, 1.9x106 and 1.7x103/ml, respectively.
In milk samples after separation these values were 1.9x104,
1.2x105, 6.5x105 and1.1x103 /ml, while in milk after heat
treatment at 74oC for 15 sec these averages were 6.1x104,
2.5x102, 1.2x103 and 4.8x103 cells/ml, respectively. In
ultrafiltered milk these counts, were 7.4x104, 2.9x102,
2.5x103 and 6.3x103 /ml, however, in retentate after heat
treatment were 8.5x102, 2.1x102, 3.1x102 and
2.5x102/ml,respectively, In precheese samples, were
2.4x103, 9.5x102, 5.3x102 and 2.7x103/ml, but in Feta
cheese samples at zero time of storage, the average
numbers were 4x102, 2.9x102, 3.3x102 and 6.6x102 cfu/g,
respectively. (II) Investigation of selected biofilm forming
bacteria at different milk contact sites of plant units after
standard CIP: Average counts of B.cereus /100/10/cm2 in
segments of raw milk line include prechiller, postchiller, tank,
pipelines and gaskets were 2.1x103, 1.9x103, 1.1x103,
2.5x102 and 1.2x102, respectively. The average
pseudomonas counts were 7x102, 6.6x102, 1.4x103, 8.7x102
and 1.3x103,respectively, however, enterococci were
detected only at gaskets surfaces with an average count of
4.4x103. Regarding anaerobes, they were detected in
average counts of 5.2x102, 4.8x102, 1.6x102, 8.6x10 and
1.2x102, respectively. Average counts of B.cereus,
enterococci and anaerobes were at tank of reconstitution unit
were 9.4x102, 1.3x102 and 2.7x102, respectively.
pseudomonas could not be detected in all of examined
samples. However in pipelines the average counts of
B.cereus and anaerobes were 8.1x102 and 2.8x10,
respectively, while pseudomonas and enterococci failed to be
detected. The averages of B.cereus, pseudomonas and
anaerobes in Triblender valve were 6.4x102, 1.8x102 and
9.5x102, respectively, and enterococci could not be detected
in all examined samples. Concerning gaskets, the average
counts of B.cereus, pseudomonas, enterococci and total
anaerobes were 1.3x102, 9.7x102, 1.5x102 and 7.3x102,
respectively. In pasteurizer unit surfaces, B.cereus averages
in pasteurizer inlet, pasteurizer outlet and plate heat
exchanger were 7x102, 2.3x103 and 1.5x104, respectively,
and gaskets not contained these microorganisms. While,
pseudomonas average counts were 2.3x102, 2.2x102 and
7.6x102, respectively, and could not be detected in plate heat
exchanger. However, enterococci, detected only at gaskets
with an average count of 2.7x102 in the examined samples.
Regarding anaerobes, they were detected in average values
of 8x102, 1.1x103, 5.7x103 and 8.6x102 in pasteurizer inlet,
outlet, plate heat exchanger and gaskets, respectively. In
ultrafiltration unit surfaces, the average counts of B.cereus
were 1.5x103, 1.1x103 and 5.9x102 in retentate side,
permeate side and tank of unit, respectively, but not detected
in gaskets.While, pseudomonas and enterococci failed to be
detected in all examined samples at all segments of
ultrafiltration unit except at gaskets, pseudomonas average
count was 3.2x102 of examined samples. Concerning
anaerobes, they were present in all segments of unit at
average numbers of 1.7x103, 1.2x102, 1.2x102 and 1.7x102,
respectively. B.cereus, pseudomonas and anaerobes
average values in vats cheese surfaces of filling unit were
8.2x102, 8.5x102 and 2.9x102, respectively. While in by-pass
valves were 9.1x102, 2.4x102 and 3x10, respectively, and
average count of enterococci was 1.3x102 and failed to be
detected in vats cheese surfaces. Regarding, gaskets the
average counts of pseudomonas, enterococci and anaerobes
were 1.7x103, 1.5x103 and 4.1x10, respectively, however
B.cereus could not be isolated from all examined samples.
(III) Improvement the efficacy of standard CIP using modified
cleaner and sanitizer in terms of controlling biofilm in uf Feta
cheese plant : The average counts of B.cereus,
pseudomonas and anaerobic in pre and post chiller of raw
milk line were 1.8x102, 1.4x102, 1.3x102, 1.2x102, 4.2x10
and 4.8x10, respectively. In tank, average B.cereus and
anaerobes counts were 1.3x102 and 2.2x10, respectively,
and pseudomonas failed to be detected in all examined
samples. However, pipelines not contained any of examined
microorganisms, while average values of pseudomonas and
anaerobes at gaskets surfaces were 1.5x102 and 2.7x10,
respectively, however, B.cereus could not be detected in all
examined samples. All tested samples were free from
enterococci from all surfaces of raw milk line after optimized
CIP. In reconstitution unit, average counts of B.cereus in
tank, pipelines and tri-blender valve were 1.2x102, 1.2x102
and 1.1x102, respectively. However, gaskets were free from
B.cereus. On the other hand, averages of anaerobes were
4.8x10, 5.5x10 and 4.2x10 in tank, tri-blender valve and
gaskets, respectively, while pipelines were free from
anaerobes. Moreover, all tested samples of surfaces of
reconstitution unit were free from both pseudomonas and
enterococci. In pasteurizer unit, B.cereus was existe only at
plate heat exchanger with an average count of 2.5x102cfu/10
cm2. However, pseudomonas isolated only from gaskets with
an average of 1.2x102cells/cm2. On the contrary, segments
of pasteurizer unit were free from enterococci, and plate heat
exchanger only contained anaerobes. Average counts of
B.cereus and anaerobes in retentate, permeate sides and
tank of ultafiltration unit were 1.3x102& 1.5x102; 1.5x102&
1.8x10 and 1.1x102 & 2x10, respectively. In gaskets B.cereus
not existed and anaerobes average count was 1.4x10
bacteria /cm2, both pseudomonas and enterococci failed to
be detected in all surfaces of ultrafilteration unit. In filling unit,
vats cheese and by-pass valve were contained B.cereus with
average count of 1.5x102 and 1.3x102cfu/cm2/10cm2,
respectively. However, gaskets were free from
microorganism, while pseudomonas isolated from gaskets
with average count of 1.6x102 cfu/cm2, while enterococci
were not detected on the surface of all segments of filling unit
after optimized CIP. With regard to anaerobes, cheese vats
were the only segment contained the microorganisms with an
average count of 3.6x10/10 cm2. (IV) Studying the effect of
optimized CIP on the microbiological criteria of milk during
production stages and uf Feta cheese at time zero of storage:
Microbiological evaluation of raw milk revealed that the
average counts/ml of B.cereus, pseudomonas, enterococci
and total anaerobic were 5.8x103, 2.5x104, 2.1x105 and
1.2x103/ml, respectively. In milk after separation were
1.6x103, 3.4x103, 1.7x104 and 4.1x102/ml, respectively,
while in milk after heat treatment at 74oC for 15 sec were
2.2x102, 1x102 and 6.6x10/ml for B.cereus, pseudomonas
and anaerobes, respectively, however enterococci could not
be isolated. In ultrafiltered milk samples B.cereus and
anaerobes could be isolated with averages of 9.1x102 and
1.8x102/ml, respectively. In retentate samples after heat
treatment their values were 2x102 and 8.5x10/ml,
respectively, but they were free from both pseudomonas and
enterococci. In precheese the average numbers of B.cereus,
pseudomonas and anaerobes were 1.4x102, 2.2x102 and
4.6x102 /ml, but in Feta cheese at zero time were 1.2x102,
1.3x102 and 1.1x102/g, respectively, in contrast enterococci
could not be detected. At the end of this study we can
conclude that the application of optimized CIP at uf Feta
cheese plant enhanced cleaning and sanitization process,
improved the quality of milk from receiving till uf feta cheese
obtained and consider one of the main efficient practical
means for control bacterial biofilm .