| |||||||||||||||||||||||||||||||||||||||||||
FNSC4180 |
 Food Factory Field Trip Old Picture |
Monday, April 30, 2018
USDA Food Safety and Inspection Service Daily Digest Bulletin
Saturday, April 28, 2018
USDA Food Safety and Inspection Service Daily Digest Bulletin
| |||||||||||||||||||||||||||||||||||||||||||
Friday, April 27, 2018
USDA Food Safety and Inspection Service Daily Digest Bulletin
| |||||||||||||||||||||||||||||||||||||||||||
Tuesday, April 24, 2018
Questions from a student
-----Original Message-----
From: LLLLLLLL
Sent: Sunday, 22 April 2018 7:12 PM
To: HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>
Subject: FNSC3180 questions
Dear Mr Kwan,
I would
like to ask some questions.
1. From Past paper 2014-15, are these answers correct? If
not, what are the answers?
B1(b)(vii)
Microaerophilic pathogenic bacteria commonly found to be related to poultry:
Campylobacter jejuni
(x) Endospors germinate in
overnight rice before frying: Bacillus
cereus 2. 'There is no universal STERILIZATION process.The time/temperature
specified for a given food depends on which microbe you are trying to kill and
the details of its heat resistence in that food.'' Is this statement correct?
3. From Past paper 2016-17, are these answers correct? If
not, what are the answers?
A2(C)Why is
the growth inhibitor used during the recovery period at 37 °C?
Growth inhibitor inhibits growth so as to ensure that cells counted are
not due to cell growth. We want to count cells that are not killed and those
recover from injury. Without growth inhibitor, more cells will be counted and
the answer will be overestimated.
4. A3(iii) Add salt to 10% AND store food at 40 °C: Clostridium perfringens: K because salt concentration is too high for
it.
(iv)Dry
food to water activity of 0.85 AND store food at 25 °C:Clostridium perfringens: NG and S. Because
it grows when food is held very warm (45-50 °C)for several hours,it does not
grow at 25°C.
5. A4 Soy sauce chicken: Samonella enterica(common in
chickens)
Ground
beef salted:Listeria monocytogenes(salt tolerant and psychrophile)
Stuffing
of roasted chicken:Clostridium perfringens(common in turkey)
Bagel:
Saccharomyces cerevisiae(yeast in fermentation of bread)
Pickled
Pork Knuckle:None(high salt con., very low pH) 6. B2 Is the microorganism
involved Norovirus??? Pizza has the highest attack rate difference and
incubation period of Norovirus(12-24 hrs)is more consistent with that of
disease(lunch:25-52hrs and dinner:18-45 hrs). Incubation period of
Staphylococcus aureus and Clostridium
perfringens are too short for the disease in this case. Am I correct?
Please answer
these questions as they are very important. Sorry for bothering you. I look
forward to receiving your reply. Thank you.
Answers
1. Correct
2. Usually we just refer to pasteurization: . 'There is no universal PASTEURIZATION process. The time/temperature specified for a given food depends on which microbe you are trying to kill and the details of its heat resistance in that food.'' STERILIZATION should be the same.
3. Correct
4. A3(iii) Add salt to 10% AND store food at 40 °C: Clostridium perfringens: K because salt concentration is too high for it.---K is incorrect, should be S
(iv)Dry food to water activity of 0.85 AND store food at 25 °C: Clostridium perfringens: NG and S. Because it grows when food is held very warm (45-50 °C)for several hours, it does not grow at 25°C.
Incorrect, should be G and S. C. perfringens is a thermophile.
5. A4 Soy sauce chicken: Samonella enterica(common in chickens)--Should be None
Ground beef salted:Listeria monocytogenes(salt tolerant and psychrophile)---correct
Stuffing of roasted chicken:Clostridium perfringens(common in turkey)---correct
Bagel: Saccharomyces cerevisiae(yeast in fermentation of bread)--incorrect, should be Aspergillus
Pickled Pork Knuckle:None(high salt con., very low pH)--correct
6. B2 Is the microorganism involved Norovirus??? Yes
Question from a student
email Q:
also i would like to ask past paper in 2016-2017. Question A3, as some of the criteria in the treatment is suitable for the bacteria growth, but the original redox potential is not in the range. Actually do some factors have a relatively importance in deducing whether the bacteria can survive or not ?
A: No. All factors are equally important
also i would like to ask past paper in 2016-2017. Question A3, as some of the criteria in the treatment is suitable for the bacteria growth, but the original redox potential is not in the range. Actually do some factors have a relatively importance in deducing whether the bacteria can survive or not ?
A: No. All factors are equally important
Question from a student
From: LLLLLLLLLLLLLLL
Sent: Monday, 23 April 2018 9:43 PM
To: HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>; HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>
Subject: Questions about FNSC3180
Sent: Monday, 23 April 2018 9:43 PM
To: HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>; HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>
Subject: Questions about FNSC3180
Dear Mr Kwan,
I would like to ask a few questions considering the content of the exam.
1. Clostridium perfringens can
survive upon addition of nitrate. Can it grow with
addition of nitrate?
2. In past
paper2016-2017 (A4), why is the answer not Salmonella Enterica?The redox -50 is
suitable for its growth. For Clostridium perfringens, it should only survive
but not grow in a salt con(9%too high). Actually, the Aw=0.9 is not suitable
for growth of both Salmonella Enterica and Clostridium perfringens.
Why is the answer Clostridium perfringens?Can you explain this question?
3. Is disease caused by Vibrio
Cholerae an infection or an intoxication?
4. Why are germinating spores
more sensitive than vegetative cells?It is the example provided when saying the
precise limit for any given species depends on the physiological state of the
cell.
5. ''The most
temperature-sensitive enzyme or process in a given cell will set the
temperature limit for growth or survival under the given conditions.'' Does it
mean that an enzyme which is with narrow temperature limit will set the
temperature limit for microbial growth?
6. In the investigation exercise, does the
question'' Can you hypothesize a scenario of what happened?'' mean that
I have to state events that caused the outbreak in the answer?
I look forward to receiving your reply on the blog. Thank you very much.
Dear LLLLLL,
Answers to your questions:
1. No
2. You are correct. Should be none. My mistake.
3. Infection
4. Germinating spores are more active physiologically. More active cells are more susceptible to environmental stress
5. No, it means the enzyme with the lowest maximum temperature limit will set the temperature limit for growth and survival. One resumption is that the enzyme is an important enzyme.
6. Yes
2. You are correct. Should be none. My mistake.
3. Infection
4. Germinating spores are more active physiologically. More active cells are more susceptible to environmental stress
5. No, it means the enzyme with the lowest maximum temperature limit will set the temperature limit for growth and survival. One resumption is that the enzyme is an important enzyme.
6. Yes
Best,
HS Kwan
Question from a student
Q:
From: WWWWWWWWWWW
Sent: Saturday, April 21, 2018 6:52:22 PM
To: HS Kwan, Prof. (SLS)
Subject: Final examination of FNSC 3180
Sent: Saturday, April 21, 2018 6:52:22 PM
To: HS Kwan, Prof. (SLS)
Subject: Final examination of FNSC 3180
Dear Professor Kwan,
I am
Tam Wan Yuk from class FNSC3180. For the scope of final examination, do we need
to study Protozoa and Parasitic Worms (P.34-40), Fungal Toxin (P.41-45), Food
Spoilage (P.93-100), Controversial Preservation (P.101-106) and Legal
Considerations and Food Safety Programs (P.107-111)?
Thank you for your attention.
Best regards,
A: Dear WWWWWWWWWWWWWThe topics have not been covered and will not be included, except Food Spoilage which I explained briefly in the last lecture.
Question from a student
Q:
From: HHHHHHHHH
Sent: Tuesday, 24 April 2018 4:48 PM
To: HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>
Subject: Questions from a FNSC3180 student
Sent: Tuesday, 24 April 2018 4:48 PM
To: HS Kwan, Prof. (SLS) <hskwan@eservices.cuhk.edu.hk>
Subject: Questions from a FNSC3180 student
I am a student from FNSC3180, I have some questions concerning the past exam questions.
For 2016-17 past paper A3, may I ask if we need to consider the "initial characteristics of the food" on top of the treatment/processes mentioned in questions i. to x.? Would it be possible that the treatment/process shows there will be bacteria growth but the "initial characteristics of the food" limits it?
And for A3 iv., may I ask why the answer is G, S? The water activity is of the food 0.85 but in the notes the minimum Aw for C. perfringens is 0.95, so I think the bacteria cannot grow in this case?
Thank you for taking time to read my email.
A: Dear HHHHHH,
1. Yes, you need to consider all characteristics of the food.
2. It was a mistake I made on the blog, A3 iv. Should be NG, S.
Best,
HS KWAN
Explaining the bacterial injury experiment once again
The bacterial injury experiment was explained again. To understand the experiment better, you can read the question A2 of past paper 201617 together with the curve in the notes.
Food Alert: Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7
Dear Sir/Madam,
We have issued a food alert regarding "Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7".
Please check the following link for further details.
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fa/2018_327.html
For further enquiries, you may contact us at <rc@fehd.gov.hk>.
Should you wish to cancel your registration with E-news, please notify us either by email (same address as above) or by fax (no. 2893 3547).
Centre for Food Safety
***********************************************************
各位先生/女士：
我們剛發出關於"美國亞利桑那州生產的蘿蔓生菜疑受O157：H7型大腸桿菌污染"的食物警報。
詳情請參閱以下連結:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fa/2018_327.html
如有任何查詢，請與我們聯絡(電郵地址：rc@fehd.gov.hk)。
如想取消[食物安全電子信息]的用戶登記，請透過上述電郵地址或傳真號碼 2893 3547 通知我們。
食物安全中心
Food Alert: Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7
Dear Sir/Madam,
We have issued a food alert regarding "Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7".
Please check the following link for further details.
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fa/2018_327.html
For further enquiries, you may contact us at <rc@fehd.gov.hk>.
Should you wish to cancel your registration with E-news, please notify us either by email (same address as above) or by fax (no. 2893 3547).
Centre for Food Safety
***********************************************************
各位先生/女士：
我們剛發出關於"美國亞利桑那州生產的蘿蔓生菜疑受O157：H7型大腸桿菌污染"的食物警報。
詳情請參閱以下連結:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fa/2018_327.html
如有任何查詢，請與我們聯絡(電郵地址：rc@fehd.gov.hk)。
如想取消[食物安全電子信息]的用戶登記，請透過上述電郵地址或傳真號碼 2893 3547 通知我們。
食物安全中心
Food Alert: Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7
Dear Sir/Madam,
We have issued a food alert regarding "Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7".
Please check the following link for further details.
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fa/2018_327.html
For further enquiries, you may contact us at <rc@fehd.gov.hk>.
Should you wish to cancel your registration with E-news, please notify us either by email (same address as above) or by fax (no. 2893 3547).
Centre for Food Safety
***********************************************************
各位先生/女士：
我們剛發出關於"美國亞利桑那州生產的蘿蔓生菜疑受O157：H7型大腸桿菌污染"的食物警報。
詳情請參閱以下連結:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fa/2018_327.html
如有任何查詢，請與我們聯絡(電郵地址：rc@fehd.gov.hk)。
如想取消[食物安全電子信息]的用戶登記，請透過上述電郵地址或傳真號碼 2893 3547 通知我們。
食物安全中心
Food Alert: Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7
Dear Sir/Madam,
We have issued a food alert regarding "Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7".
We have issued a food alert regarding "Romaine lettuce produced in Arizona, US suspected to be contaminated with Escherichia coli O157:H7".
Please check the following link for further details.
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fa/2018_327.html
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fa/2018_327.html
For further enquiries, you may contact us at <rc@fehd.gov.hk>.
Should you wish to cancel your registration with E-news, please notify us either by email (same address as above) or by fax (no. 2893 3547).
Centre for Food Safety
***********************************************************
各位先生/女士：
我們剛發出關於"美國亞利桑那州生產的蘿蔓生菜疑受O157：H7型大腸桿菌污染"的食物警報。
詳情請參閱以下連結:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fa/2018_327.html
Should you wish to cancel your registration with E-news, please notify us either by email (same address as above) or by fax (no. 2893 3547).
Centre for Food Safety
***********************************************************
各位先生/女士：
我們剛發出關於"美國亞利桑那州生產的蘿蔓生菜疑受O157：H7型大腸桿菌污染"的食物警報。
詳情請參閱以下連結:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fa/2018_327.html
About salt tolerance
Q: On the web, we can find that salt tolerance limit of Clostridium perfringens is 6%, different from the 10% we used in the notes. How to judge?
A: You can always find different limits for the parameters of a microbe. There are many factors affecting the reporting of the limits. The better way to deal with this is to use the least stringent one to assume the growth or survival of the microbe. For example, if you find 6-10% as the salt content limit for C. perfringens, take it that it can grow at 10% salt. You will have a good margin to be safe.
In the real world, you will need to do the experiment to determine the limits for your own target food and microbe.
The main effect of adding salt is to lower water activities. Low water activities will never kill all the microbes.
A: You can always find different limits for the parameters of a microbe. There are many factors affecting the reporting of the limits. The better way to deal with this is to use the least stringent one to assume the growth or survival of the microbe. For example, if you find 6-10% as the salt content limit for C. perfringens, take it that it can grow at 10% salt. You will have a good margin to be safe.
In the real world, you will need to do the experiment to determine the limits for your own target food and microbe.
The main effect of adding salt is to lower water activities. Low water activities will never kill all the microbes.
Past paper 201617
Q. B3e. How to calculate?
A: Target set: 900/ml to 1/ml. Reduction is ~1000-fold. You have the D value of the temperature 98C and the time of 21 sec. Is the combination giving 1000-fold reduction or more? If yes, then the industrial standard is sufficient.
A: Target set: 900/ml to 1/ml. Reduction is ~1000-fold. You have the D value of the temperature 98C and the time of 21 sec. Is the combination giving 1000-fold reduction or more? If yes, then the industrial standard is sufficient.
Past paper 201415
Q: B4e. How to do it? "The canning temperature can be raised 15°C without any adverse effect on the quality of the canned hams. Hence, the technician would like to use l20°C in the canning process to treat this lot of contaminated ham. Calculate the treatment time required at 120°C to achieve (i) the acceptable cell density for this contaminated lot and (ii) the acceptable cell densities of the microorganisms of the regular lot of ham after canning with this new process. Justify your answer and explain. (10 marks)"
A: Use the Z value to calculate the new D value at 120C. Use this new D value to calculate your treatment timed for the targeted reductions for bacteria and for spores. You need to calculate twice, one for the contaminated lot and one for the regular lot to complete your answer.
A: Use the Z value to calculate the new D value at 120C. Use this new D value to calculate your treatment timed for the targeted reductions for bacteria and for spores. You need to calculate twice, one for the contaminated lot and one for the regular lot to complete your answer.
Past paper 201617
Q: A3, How to judge whether the bacteria would be killed or could not grow under the condition?
A: You have to know the characteristics of the bacteria. The bacteria in this question are those with some distinct characteristics. You have to match their characteristics to the treatment or process to judge whether they can be killed or still be able to grow.
A: You have to know the characteristics of the bacteria. The bacteria in this question are those with some distinct characteristics. You have to match their characteristics to the treatment or process to judge whether they can be killed or still be able to grow.
Past examination paper 201617
Q: A3, which parameter would be the most important? what about the parameters not mentioned in the treatment or process?
A: Importance of parameter depends on the parameter itself and the target microbe, no strict rules. The parameters not mentioned may remain the same, but changing one thing may have multiple effects and change other parameter. for example, adding salt changes also the water activities, or removing oxygen would change also the Redox.
A: Importance of parameter depends on the parameter itself and the target microbe, no strict rules. The parameters not mentioned may remain the same, but changing one thing may have multiple effects and change other parameter. for example, adding salt changes also the water activities, or removing oxygen would change also the Redox.
Salt content limits
Q: salt content higher than the maximum limit, will the bacteria die?
A: salt content primarily affects water activities, bacteria would survive at low water activities.
A: salt content primarily affects water activities, bacteria would survive at low water activities.
Monday, April 23, 2018
why gram positive bacteria survive better than gram negative bacteria?
A: Depends on the type of challenges, if it is high temperature, spore formers of Gram positive bacteria can survive a lot better.
Review session: Nitrate inhibiting anaerobic bacteria growth?
A: Yes, nitrate is an oxidizing agent, raises Redox and inhibit anaerobic bacteria growth.
Thermal death time curve and F value?
A: F value is your target thermal death value, can be 2D, 3D, ................12D, any value depend on your target thermal reduction. You can draw the curve in many ways to get the temperature-time combination to reach your target. One example is given in the notes.
Past paper 201617 C
Q: A2. Recovery not back to log colonies number of 9.4/ml ? but only 8.5?
A: There was actual killing of the bacteria at 52C. Recovery can never go back to 9.4.
Q; a2 vi. c. botulinum killed by low level of oxygen?
A: yes.
A: There was actual killing of the bacteria at 52C. Recovery can never go back to 9.4.
Q; a2 vi. c. botulinum killed by low level of oxygen?
A: yes.
Past paper 201617 B
Q: B3 a., d ?
A: B3 a. No need. High acid food--low pH
B3 d. 3D reduction--900/1000 /ml = 0.9/ml. Temperature does not matter.
A: B3 a. No need. High acid food--low pH
B3 d. 3D reduction--900/1000 /ml = 0.9/ml. Temperature does not matter.
Past paper 201617 A--Please note the change in answers
Q: A3 iii, iv, ix
A: iii, G, S iv. NG.S. G, S. was a mistake ix. G. S.
Q: A4 Soy sauce chicken--bacteria? Bagel?
A.C. perfringens. should be none Bagel: Aspergillus
A: iii, G, S iv. NG.S. G, S. was a mistake ix. G. S.
Q: A4 Soy sauce chicken--bacteria? Bagel?
A.
Review question 1 201617 paper B4
Q: B4 f.
A: Find the odd one. It was No. 24 patient. Incubation period much longer than the other patients in the two outbreaks.
A: Find the odd one. It was No. 24 patient. Incubation period much longer than the other patients in the two outbreaks.
Friday, April 20, 2018
Question from a student
From CCCC,
Dear
Professor Kwan,
I am
xxxxxxxxxx from class FNSC3180. For the open book examination, may I ask
what types of materials can we bring for the final?
Thank
you for your attention.
Q: Any book, notes, or charts can be used in the OPEN BOOK examination. Of course, only paper materials.
Thursday, April 19, 2018
Notes of Open Book Examination
Please note the following about Open Book Examination
1. You need to familiarize with the materials, you may not have enough time to search for everything. If you can answer without reading through your notes and books, answer right away, confirm later on. The time will always be tight.
2. Know the basic principles of outbreak analysis, thermo-treatment calculations, microbial growth, etc. You should know how to apply them.
3. Questions may not be always similar to previous years examinations.
4. Even if the questions looks similar to previous years, they may differ greatly in details. Don't answer yester-years' questions.
5. Pay attention to details.
I wish you acquire and use these skills and capabilities:
1. You need to familiarize with the materials, you may not have enough time to search for everything. If you can answer without reading through your notes and books, answer right away, confirm later on. The time will always be tight.
2. Know the basic principles of outbreak analysis, thermo-treatment calculations, microbial growth, etc. You should know how to apply them.
3. Questions may not be always similar to previous years examinations.
4. Even if the questions looks similar to previous years, they may differ greatly in details. Don't answer yester-years' questions.
5. Pay attention to details.
I wish you acquire and use these skills and capabilities:
- logical
- attention to details
- organized
- thorough
- careful in calculation
- familiarize--internalize knowledge
- read questions carefully
- good time management
- writing clearly and concisely
Open Book Examination
Dear Students,
The final examination of FNSC3180 Food Microbiology will be Open Book examination. Please check the final examination time table to make sure you know the date and time: 26 April 2018, 9:30am to 11:30am at Thomas H C Cheung Gymnasium, UC. Let me know if you have any questions.
Best,
HS Kwan
USDA Food Safety and Inspection Service Daily Digest Bulletin
| |||||||||||||||||||||||||||||||||||||||||||
Subscribe to:
Posts (Atom)