Cheese risk will be increased in cheese with

Cheese is a kind of safe and
nutritious food which made from milk The milk is acidified and the enzyme which
is rennet will be added for coagulation The solids are then separated and
pressed into final form of product It is produced in a wide range of textures
and flavours as there are soft, semi-hard and hard cheese

Cheese is
considered as a safe food due to the physicochemical and antagonistic
properties of lactic acid bacteria There are 04 % of foodborne outbreaks
involved contaminated cheese in 2006 in the European Union Most of the
foodborne outbreaks are due to the presence of Staphylococcus aureus as it often causes mastitis in cows which
results in milk contamination

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There are some foodborne illnesses
related to cheese consumption have happened in many countries The
microorganisms that involved in cases of foodborne illness are Listeria Monocytogenes, Staphylococcus Aureus, and Escherichia Coli Most of the cheese-associated foodborne illnesses that
involved pathogenic bacteria are occurred
in soft cheese

Other than
foodborne pathogens in cheese, there are some factors also contribute in this
foodborne issues such as pH, water activity, time, and starter culture The microbial risk assessments are
identified which the risk will be increased in cheese with high moisture
content especially for raw milk cheese, but the risk can be reduced by the
preventions on preharvest and postharvest

The cheese related
foodborne illnesses have been generally linked to soft cheese or cheese made from
raw or unpasteurized milk, but rarely in hard and low moisture cheese

Hispanic-style cheeses are being made from raw milk which
generally characterized as soft, high moisture, mild fresh milk flavour and
ready for consumption immediately after manufacture Soft cheeses are
challenging to produce due to the pathogen Listeria monocytogenes as it has
ability to grow in a wide range of temperatures, under refrigerated storage and
under high salt concentration environment Hence, special care must be taken to
prevent contamination during the production of fresh cheeses

The soft cheese
with high moisture content and low acidity create a favour condition for growth
of pathogenic bacteria such as
Staphylococcus aureus and Listeria
monocytogenes as well as the improper handling and sanitation during the process
of making cheese The foodborne cases happened when there is more than 5 Log
CFU/mL of pathogenic bacteria that lead to the production of heat-resistant
enterotoxin The ingestion of 20 to 1,000 ng of the enterotoxin will cause
typical symptoms of S aureus

The common symptoms
including difficulty breathing, fever, malaise and serious infections will lead
to pneumonia which is infection of the lungs or bacteremia which is bloodstream
infection One of the cases is happened in England which the mold-ripened
semisoft blue cheese are contaminated by the S aureus and resulting in 155
illnesses The improper cheese pasteurization also resulted in 16 cases of S aureus foodborne illness at USA in
1981 Recently, there are 6 S aureus
outbreaks happened in France because of the consumption of enterotoxin type E
in soft cheese that was processed during weeks of 40 and 41

Recent studies have shown that Listeria contamination
occurs predominantly through transportation and storage of finished product,
multiple cheese varieties were tested positive for the outbreak strain It was
suggested that it was due to post-pasteurization contamination of pasteurized
milk Researchers pointed out that preservation methods fail to take into
account of the sensory impact and consumer acceptability They also found out
that the antimicrobial efficacy of a Listeria bacteriophage endolysin may
address limitations of current antilisterial processes for fresh cheeses Thus,
enzyme PlyP100 can be used as an alternative preservation in addressing a food
safety issue

Studies on the effects of endolysin PlyP100 and compared
its lytic activity in vitro under different environments and target organisms
It shows PlyP100 demonstrates optimal activity under pH and salt concentrations
consistent with a low-acid food matrix such as fresh cheese

The cases that related to L monocytogenes outbreaks in cheese have a relatively high fatality
rate which is 15% to 30% The common symptoms are fever, muscle aches, diarrhea
and nausea When the infection spreads to nervous system, the symptoms are stiff
neck, headache, loss of balance, convulsions or confusion There are L monocytogenes
outbreak in 2005 after the consumption of Tomme which is one type of soft
cheese and this cheese was contaminated with L monocytogenes serotype 1/2a There is a study reported that
Quargel (acid curd cheese) contaminated with L monocytogenes serotype 1/2a result in four deaths out of 14 cases
in Austria and Germany in 2009

Salmonella is one of the common foodborne pathogen Salmonella strains are
gastroenteritis-inducing pathogens and some of the Salmonella serotypes are involved in cheese-borne outbreaks The
common symptoms of Salmonella
infection are bloody stools, diarrhea, fever, headache and others In 2013, consumption
of raw Cashew cheese linked to the outbreak of Salmonella Stanley in California
(15 cases), Nevada (one case), and Wyoming (one case) in the US Other than
that, shiga toxin-producing E coli (STEC) strains such as E coli O157:H7 are also one of the important and common foodborne
pathogens E coli strains are able survive
and grow during cheese making process and maturation, especially in soft cheese
The common symptoms in the early stage of infection are nausea, vomiting,
malaise, loss of appetite and diarrhea while the later symptoms of E coli
O157:H7 infections are hemorrhagic diarrhea, anemia, severe dehydration,
shortness of breath, fatigue, jaundice, kidney failure, seizures and others In
2003, E coli O157:H7 are involved in
13 outbreaks cases due to the presence of E
coli that caused contamination in unpasteurized Gouda cheese-in Canada
Recently, there was a multistate outbreak of E coli O157:H7 infections in Gouda
cheese and the outbreak involved 38 people in five states which are Arizona,
California, New Mexico, and Nevada

Raw milk originated from the udder of milking animals which
micrococci constitute the predominant microflora of raw milk produced under
sanitary conditions Some micrococci are thermoduric and capable of surviving
heat treatments which includes modern pasteurization hence it can be present in
heat-treated milks and cheeses According to Bhowmik and Marth’s review, the
role of micrococci in cheese-ripening process is unclear and likely depend on
the individual strain used It is most likely that natural occurring micrococci
helps in giving positive flavour development in aged cheeses Studies shown that
the enhancement of flavour in cheese could be due to not only the micrococcal
enzymatic activity but also the symbiotic activation of lactobacilli and

Streptococci are commonly isolated from raw milk while
Streptococcus thermophiles can be found in pasteurized milk Thermoduric
bacteria may accumulate in the regeneration section of the heat exchanger if
pasteurization equipment is not cleaned after using for a long period of time
This species of bacteria can produce enough carbon dioxide over time in Gouda
cheese and render the yeasty and unclean flavour

Most of the time, if milk is hygienically collected from
healthy flock, using clean milking and storage equipment, the concentration of
contaminating organisms can be less than 5000 CFY/mL and populations less than
20000 CFU/mL is already considered as good sanitary practices However,
outgrowth of microorganisms may increase due to the milk being exposed to
elevated temperatures (>7°C) during storage or transportation

Back in the days where modern refrigeration was not
invented, milk was either not cooled or only cooled to ambient temperature
which encourages the growth of lactic acid bacteria (LAB), which is
gram-positive bacteria, non-motile and non-spore forming bacteria with
fermentative metabolism Even though most production of cheeses uses lactic acid
bacteria as starter culture, there are many wild-type LAB that do not produce
significant amounts of acid, they are referred as non-starter LAB (NSLAB) They
can be presence in raw milk as well as in pasteurized milk as the result of
both heat resistant and post-processing contamination

According to Lawrence and colleagues, the type of NSLAB in
Cheddar cheese are different between countries and facilities due to the
numerous species and strains in a dynamic state during ripening of the cheese
NSLAB growth can impart both positive sensorial attributes and defects which
includes high acidity, off-flavours and excessive gas production that will
leads to collapse of the cheese structure The formation of carbon dioxide is
believed to be result from the metabolism of carbohydrates, citrate or amino
acids However, amino acids metabolites are also related to the flavour defects
in cheese such as sulphurous, phenolic, putrid and mealy The presence and
growth of NSLAB in Cheddar cheese associates with the formation of white spots
of calcium lactate pentahydrate crystals on the cheese surface So, if the
growth of substrates in cheese can be limited, addition of selected strains to
cheese milk as adjunct starter cultures might be able to outcompete the wild
NSLAB in order to have better control of the ripening process

Proper cooling and storage of milk are one of the most
critical process line in preventing the outgrowth of contaminating
microorganisms which includes pathogens in milk prior to cheese manufacture The
rapid cooling and refrigerated storage of milk that is usually done in order to
prevent growth of microorganism, however, this favours the growth of
psychrotrophic organisms They grow at the temperature below 7?C Even if the
equipment is cleaned with sanitizers, milk residues may form and accumulate in
the cracked part which may be the source of the contamination The growth and
presence of psychrotrophs and heat-stable enzymes causes various defects in
cheese which include surface discolouration and off-flavours

Besides that, Pseudomonas species are one of the dominant
microorganism presence in raw milk Low temperatures of the environment may
actually encourage the production of proteinases by Pseudomonas species, the
enzymatic activity is the cause of changing in cheese texture It causes the
should-be solid cheese into running paste and produces off-flavours including
bitterness and soapy rancidity Proper cleaning and sanitation can help in
minimizing the contamination of milk by Pseudomonas species but manufacturers
have to keep in mind to check on the water source as it is the main
contamination source for Pseudomonas species

The increase in plasmin and non-plasmin proteolytic
degradation of casein which can occur in the udder prior to milking when
temperatures are more conducive to enzymatic activity The degradation can lead
to the decrease in casein which is for curd formation, therefore it reduces the
curd tension and curd firmness The decreased in curd tension increases the loss
of fat, protein and total solids in the whey The clotting enzymes are affected
by elevated pH which also increase the clotting time and rate of curd firming

The secretion of macrophage-derived lipolytic enzymes
during prolonged mammary gland infections can damage the milk fat globule
membrane, making it more susceotible to lipoprotein lipase activity elevating
the production of free fatty acids that causes rancid in cheese

The microbial risk assessment is carried out in
most of the country including hazard identification, exposure assessment,
hazard characterization, and risk characterization to prevent and avoid the
occurrence of foodborne illnesses, lower the risk of foodborne illness
outbreaks, and also establish the criteria of microbe The additional risk
management measures are carried out especially for high moisture cheese and
also soft cheese to prevent the growth of pathogenic bacteria There are studies
stated the contamination that associated with L monocytogenes may occur in soft-ripened cheese after postharvest,
especially during handling in ripening rooms, wrapping packing stage, and
cutting stage There are reports showed that the risk of having outbreaks from
raw milk cheese was higher than pasteurized milk cheese by using a quantitative
models to predict the risk of L
monocytogenes in cheese and also calculate the probability of invasive
listeriosis in soft cheese Even though the milk undergo pasteurization process,
soft cheese might be contaminated by L
monocytogenes due to postharvest contamination Hence, microbial risk
assessment studies are indicated that raw milk soft cheese has higher risk than
pasteurized milk cheese and also low moisture cheese for L monocytogenes infection Besides, Brie and Camembert cheeses are undergo
fermentation processing and the probability of severe listeriosis was higher in
Brie cheese compared to Camembert cheese This might due to higher prevalence of
L monocytogenes in Brie cheese and
therefore, it can be concluded that prevalence of foodborne pathogen in cheese
significantly affect the microbial risk


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