Question 9 from 2012-13 examination paper

Question 9              2012-13 

a. F value?

At pH=4.0
Spoilage bacteria : D=0.001min----10/0.001=10000D
Bacterial spores:    D=0.1 min----10/0.1=100D
Fungal spores:        D=0.002 min ----10/0.002=5000D

Actual set F value= D values above

Sterilization:         10 min at 105C

Alternative answer: F=required D.

Bacteria: 10D
Bacterial spores: 8D
Fungal spores: 8D

b. Actual D?

Because actual pH is 4.5
At pH4.5 10 min at 105C

Spoilage bacteria : D=0.01min----10/0.01=1000D
Bacterial spores:    D=2 min----10/2=5D  (----failed)
Fungal spores:        D=0.02 min ----10/0.02=500D

c. Cell densities?

Per ml
Spoilage bacteria : 1000/ml*10^-1000=10^-997
Bacterial spores:    100/ml*10^-5=10^-3
Fungal spores:        100/ml*10^-500=10^-498

d. One more time, 10 min at 105C?

Per ml
Spoilage bacteria : 10^-997/ml*10^-1000=10^-1997
Bacterial spores:    10^-3/ml*10^-5=10^-8
Fungal spores:        10^-498/ml*10^-500=10^-998

OK.  Bacterial spores:    10^-8/ml < 10^-6/ml requirement

e.  The technician was correct.

f.  New process?

1. First calculate time required for 105C sterilization to achieve target reduction of bacterial spores density to 10^-6/ml.

Number of D required for bacterial spores = 8

Bacterial spores D value at 105C = 2 min

Therefore, time required at 105C = 16 min

2. Calculate the cost:   (16min/10min)*$20=$32

3. Calculate time required for 120C sterilization to achieve target reduction of all microbes to acceptable densities.  Use Z values to get to new D values, then calculate as above. 

Time required at 120C = 1.6min

4. Calculate the cost when changed to 120C: (1.6min/1min)*$5=$8

5. Compare the two costs $8<$32

Better to use 120C for 1.6min

B5 calculation

FNSC 4180 2013-2014 2^ndterm

B3.

a.         Roasted Turkey is the most suspected food. Pizza is kept at 65-70^oC. Therefore,    both Staphylococcus aureus and its toxin won't appear in food. The toxin is          decomposed at 60 ^oC. Sushi is stored with ice, it is unlikely that Salmonella can    grow. Also, the attack rate for roast turkey is quite high, which is 0.35.

Answer: Sorry. You are wrong. Need to use the difference of attack-rates between ate and did not eat to deduce the answer. 

b.   The microorganism inviolved is C. perfringens, which incubation period is usually at typically 8-12 hours. The calculated incubated period is 8 hours as dinner starts at 7:00pm on sat and the last patient went to hospital at 4:00am on Sunday. The food involved is roasted turkey. The bacteria is found on vegetable and used as turkey stuffing. The surface of the turkey is cooked. However, the things inside the turkey may not be cooked sufficiently with temperature higher than 60 degree. The bacteria can form spore, which is activated by heating 40-50 degree. Therefore, the bacteria present inside the chicken after it is cooked. It usually presents in small number. However, the turkey transported to picnic site at room temperature, which allow them to proliferate to infective dose, which is 10⁶ -10⁷ cell per gram.

Answer: Make the story according to the answer in a. above. Use microbe properties and food process information to make the story.

B5.

a. bacteria: 100logD                  Not logD, just D; need to show calculation: 25min/0.25min=100 (D)

  Bacterial spore: 10logD                                        25min/2.5min=10   (D)

  Fungal spore: 50logD                                           25min/0.5min=50   (D)

b. bacteria: 10³ /ml                 10^5/ml/10^100=10^-95/ml  OR power 5-100= -95--     10^-95/ml

  Bacterial spore: 10³/ ml                      10^4/ml/10^10=10^-6/ml

  Fungal spore: 10^-50 / ml                       10/ml/10^50=10^-49/ml

c. bacteria: No, higher than the acceptable cell density   Incorrect

  Bacterial spore: No, higher than the acceptable cell density  Correct!!!

  Fungal spore: Yes, lower than the acceptable cell density   Correct!!!

d.

	D value at 120oC	Z value
Spoilage bacteria	0.025 mins incorrect--0.0025min	7.5 oC
Bacterial spores	0.25 mins Correct	15 oC
Fungal spore	0.05 mins Correct	15 oC

Acceptable cell density: Incorrect

  bacteria: 8logD                     10^-8/ml

  Bacterial spore: 8logD          10^-8/ml

  Fungal spore: 6logD             10^-6/ml

Treatment time required at 120 to achieve accepted cell density foe contaminated lot:

  bacteria: 8 x 0.025 = 0.2 mins      Incorrect  13*0.0025= 0.02 mins

  Bacterial spore: 8 x 0.25 = 2 mins   Incorrect  12*0.25=3 min

  Fungal spore: 6 x 0.05 = 0.3 mins    Incorrect  7*0.05=0.35 min

Only half of the answer provided here. Need to reduce the density of the most heat resistant microbe to the acceptable density. The densities of the other microbes would meet the requirement simultaneously.

Answer: 3 min at 120C

density of the microorganism of the regular lot of ham after canning with new process:

bacteria: 0.001 /ml                   

bacterial spore: 0.1 /ml

fungal spore: 1X10^-500 /ml

Answer: 

1. Calculate new D values at 120C for 3 min as a. above
2. Use new D values to calculate cell densities as b. above

B5--Questions from student 20150426

FNSC 4180 2013-2014 2^ndterm

B3.

a.         Roasted Turkey is the most suspected food. Pizza is kept at 65-70^oC. Therefore,    both Staphylococcus aureus and its toxin won't appear in food. The toxin is          decomposed at 60 ^oC. Sushi is stored with ice, it is unlikely that Salmonella can    grow. Also, the attack rate for roast turkey is quite high, which is 0.35.

b.   The microorganism inviolved is C. perfringens, which incubation period is usually at typically 8-12 hours. The calculated incubated period is 8 hours as dinner starts at 7:00pm on sat and the last patient went to hospital at 4:00am on Sunday. The food involved is roasted turkey. The bacteria is found on vegetable and used as turkey stuffing. The surface of the turkey is cooked. However, the things inside the turkey may not be cooked sufficiently with temperature higher than 60 degree. The bacteria can form spore, which is activated by heating 40-50 degree. Therefore, the bacteria present inside the chicken after it is cooked. It usually presents in small number. However, the turkey transported to picnic site at room temperature, which allow them to proliferate to infective dose, which is 10⁶ -10⁷ cell per gram.

B5.

a. bacteria: 100logD

  Bacterial spore: 10logD

  Fungal spore: 50logD

b. bacteria: 10³ /ml

  Bacterial spore: 10³/ ml

  Fungal spore: 10^-50 / ml

c. bacteria: No, higher than the acceptable cell density

  Bacterial spore: No, higher than the acceptable cell density

  Fungal spore: Yes, lower than the acceptable cell density

d.

	D value at 120oC	Z value
Spoilage bacteria	0.025 mins	7.5 oC
Bacterial spores	0.25 mins	15 oC
Fungal spore	0.05 mins	15 oC

Acceptable cell density:

  bacteria: 8logD

  Bacterial spore: 8logD

  Fungal spore: 6logD

Treatment time required at 120 to achieve accepted cell density foe contaminated lot:

  bacteria: 8 x 0.025 = 0.2 mins

  Bacterial spore: 8 x 0.25 = 2 mins

  Fungal spore: 6 x 0.05 = 0.3 mins

density of the microorganism of the regular lot of ham after canning with new process:

bacteria: 0.001 /ml

bacterial spore: 0.1 /ml

fungal spore: 1X10^-500 /ml

Coverage of topics in final examination of FNSC3180

Question from some students:

I would like to ask that will the Food Fermentations and Microbial Spoilage be covered in the final examination? Because in the revised schedule, these topics are on lecture 38-40, while the lectures that listed for final examination is 12-37. 

Since some of it has been discussed during the class, so I am wondering that will these be examined? 

Answer:

Yes. It will be covered in the final examination. Other topics covered in the final lectures will be included in the final examination also.

I am sorry that there is a mistake in the revised schedule on the lecture numbers.

Best,

HS Kwan

Review Sessions

Dear Students,

Review sessions are scheduled on:

27/4        10:30am -- 12:15am Science Centre L3

28/4         10:30am -- 12:15am Science Centre L3

Come to clarify your questions on the course materials and past examinations

Lecture 20150312

Food Allergen Alert: Undeclared allergen found in prepackaged snacks produced in Canada 食物致敏物警報: 加拿大預先包裝小食未有標示致敏物

Dear Sir/Madam,

We have issued a food allergen alert regarding "Undeclared allergen found in prepackaged snacks produced in Canada".

 

Please check the following link for further details.

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_e.pl?record=101

 

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"加拿大預先包裝小食未有標示致敏物"的食物致敏物警報。

詳情請參閱以下連結:

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_c.pl?record=101

 

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 - A batch of raisins detected with excessive preservative 食物警報 - 一批防腐劑含量超標的葡萄乾

Dear Sir/Madam,

We have issued a food alert regarding " A batch of raisins detected with excessive preservative".

 

Please check the following link for further details.

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_e.pl?record=100

 

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"一批防腐劑含量超標的葡萄乾"的食物警報。

詳情請參閱以下連結:

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_c.pl?record=100

 

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 –French raw cow

Dear Sir/Madam,
 
We have issued a food alert regarding " French raw cow's milk cheese suspected to be contaminated with Listeria monocytogenes ".

 

Please check the following link for further details.

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_e.pl?record=99

 

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"食物警報 –法國生牛乳芝士懷疑受李斯特菌污染"的食物警報。

詳情請參閱以下連結:

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_c.pl?record=99

 

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

 

 

Question from a student

Question:

I am a student from class FNSC3180. I have received the revised schedule and have some question about the exam.

As you mentioned that the final exam will cover topics from lecture 12-37, will the exam also cover the topics of lecture 38-40?

I hope yyou can answer my question. Looking forward to your reply.

Answer:

Dear JJJJ,

As I have announced in today's lecture that all materials covered after the mid-term examination will be covered in the final examination.

E-news - 16.04.2015

致食物安全電子資訊訂閱者:
Dear E-news recipients,

以下資訊已上載到食物安全中心(中心)網站:
News on the Centre for Food Safety (CFS) online:

食物安全焦點(2015年4月第105期)
Food Safety Focus (105th Issue, April 2015)

今期熱門焦點包括:
The topics of the current issue are:

‧ 二零一四年有關食肆及食物業的食物中毒個案回顧
‧  Review of Food Poisoning Outbreaks Related to Food Premises and Food Business in 2014
‧ 家禽業使用激素？
‧ Using Hormones in Poultry Production?
‧ 甲型肝炎與食物
‧ Hepatitis A and Food
‧ 愛爾蘭多尼戈爾郡生蠔被禁入口
‧ Import of Raw Oysters from Donegal County, Ireland Banned

歡迎到以下網頁閱覽上述月刊:
You are most welcome to browse through the publication at:

中文:
http://www.cfs.gov.hk/tc_chi/multimedia/multimedia_pub/multimedia_pub_fsf.html
English:
http://www.cfs.gov.hk/english/multimedia/multimedia_pub/multimedia_pub_fsf.html

世界衞生日2015：食物安全
World Health Day 2015: Food Safety

每年的4月7日是世界衞生日，亦是世界衞生組織(世衞)的成立周年紀念日，世衞把2015年世界衞生日的主題定為「食物安全」。為配合今年的世界衞生日，中心在網站設立了專頁，向市民和業界推廣食物安全的重要性，並呼籲各界攜手提升食物安全。專頁除提供與食物安全有關的豐富資訊外，亦載有中心舉辦的講座和工作坊等活動詳情。
World Health Day, which falls on April 7 every year, is also the birthday of the World Health Organization (WHO). The WHO has chosen "Food Safety" as the theme for the World Health Day in 2015. To tie in with this year's World Health Day, the CFS has set up a dedicated webpage to promote the importance of food safety for the public and the trade, and to call for concerted efforts from all sectors in the community to enhance food safety. Apart from extensive information on food safety, details of activities organised by the CFS, including seminars and talks, can also be found on the webpage.

詳情請參閱以下專頁:
Please click on this dedicated webpage for details:

中文:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fst/whatsnew_fst_World_Health_Day_2015.html
English:
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fst/whatsnew_fst_World_Health_Day_2015.html

已獲小量豁免產品名單
List of Small Volume Exemption Products

根據小量豁免制度，在香港每年銷售量不超過30,000件的相同版本預先包裝食物，可獲授予營養標籤豁免。有關豁免產品名單現已上載中心網頁。
Under the Small Volume Exemption (SVE) Scheme, prepackaged foods of the same version with annual sales volume in Hong Kong not exceeding 30,000 units may be granted with exemption from providing nutrition labelling. List of SVE products has been uploaded onto the CFS website.

詳情請參閱以下網頁:
Please click on this webpage for details:

中文 :
http://www.cfs.gov.hk/tc_chi/programme/programme_nifl/files/SVE_exempted_product_c.pdf
English:
http://www.cfs.gov.hk/english/programme/programme_nifl/files/SVE_exempted_product_e.pdf

食物安全巡迴展覽
Roving Exhibition on Food Safety

4 月下旬的巡迴展覽內容包括營養標籤、預防食物交叉污染、天然毒素、食物安全五要點、孕婦食物安全建議、雪卡毒素及食物安全條例。展覽將設於新灣仔街市、北區政府合署及清水灣半島 (住宅 )。
The coming exhibitions will be held in late April at New Wan Chai Market, North District Government Offices and Oscar By the Sea in Sai Kung (Residential). Panels cover topics on nutrition labelling, prevention of cross contamination, natural toxins, 5 keys to food safety, food safety advice for pregnant women, ciguatoxins and Food Safety Ordinance.

請點擊查看具體時間 :
Please click to see the schedule:

中文 :
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_act/whatsnew_act_Roving_Exhibition_2015.html
English:
http://www.cfs.gov.hk/english/whatsnew/whatsnew_act/whatsnew_act_Roving_Exhibition_2015.html

食物安全中心
Centre for Food Safety

 

Food Alert – Smoked salmon manufactured by Polyfood Food 食物警報 –「保發」生產的煙三文魚產品

Dear Sir/Madam,
 
We have issued a food alert regarding "Smoked salmon manufactured by Polyfood Food ".

 

Please check the following link for further details.

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_e.pl?record=98&year=2015

 

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"食物警報 –「保發」生產的煙三文魚產品"的食物警報。

詳情請參閱以下連結:

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_c.pl?record=98&year=2015

 

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

 

E-news - 02.04.2015

致食物安全電子資訊訂閱者:
Dear E-news recipients,

以下資訊已上載到食物安全中心(中心)網站:
News on the Centre for Food Safety (CFS) online:

2015年2月份食物安全報告
Food Safety Report for February 2015

中心會每月公布「食物安全報告」，分析當月的食品監察結果，令市民可適時地獲得最新的食物安全資訊。
As a way to deliver the latest food safety information timely to the public, the CFS releases the "Food Safety Report" every month, giving an account of the food surveillance sample result analyses.

有關之新聞公報可瀏覽以下網頁 :
Please click on this webpage for the related press release:

中文:
http://www.cfs.gov.hk/tc_chi/press/20150331_0205.html
English:
http://www.cfs.gov.hk/english/press/20150331_0205.html

傳達資源小組的主題展覽 (2015年4月至6月)
Theme Exhibitions in Communication Resource Unit (April to June 2015)

中心轄下的傳達資源小組於4月至6月期間展出以「營養標籤多面睇」及「食物中的天然毒素」為主題的展覽。小組位於九龍旺角花園街市政大廈8樓，展覽活動包括播放教育短片，設置展板讓市民增加對營養標籤及食物中的天然毒素的認識，更備有各種食物安全宣傳單張供公眾取閱，歡迎到場觀賞。
Exhibitions on the theme of "Have a Closer Look at Nutrition Labelling" and "Natural Toxins in Food" are staged by the Communication Resource Unit (CRU) of the CFS, from April through June, at 8/F, Fa Yuen Street Municipal Services Building, Mongkok, Kowloon.  The exhibition includes short food safety and education videos and exhibition boards to enrich the public's knowledge on nutrition labelling and natural toxins in food.  You are welcome to join us at the CRU.

請點擊查看具體時間:
Please click to see the schedule:

中文:
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_fstr/whatsnew_fstr_food_safety_charter_Exhibitions_Talks.html
English:
http://www.cfs.gov.hk/english/whatsnew/whatsnew_fstr/whatsnew_fstr_food_safety_charter_Exhibitions_Talks.html

2015年2月份預先包裝食物之營養素含量及致敏物檢測結果
Results of Compliance Test for Nutrition Labelling and Declaration of Allergens for February 2015

《食物及藥物(成分組合及標籤)規例》之營養素含量及致敏物檢測結果2015年2月份報告已上載到中心網頁。
Monthly Report on Results of Compliance Test for Nutrition Labelling and Declaration of Allergens under the Food and Drugs (Composition and Labelling) Regulations for February 2015 has been uploaded onto the CFS website.

歡迎到以下網頁閱覽上述報告:
You are most welcome to browse through the report at:

中文 :
http://cfs.fehd.hksarg/tc_chi/whatsnew/whatsnew_act/NL_Compliance_Test_Results_FEB_2015.html
English:
http://cfs.fehd.hksarg/english/whatsnew/whatsnew_act/NL_Compliance_Test_Results_FEB_2015.html

食物安全巡迴展覽
Roving Exhibitions on Food Safety

4月的巡迴展覽內容包括食物安全條例、 控制食物温度、天然毒素、營養標籤、預防食物交叉污染、食物安全五要點、孕婦食物安全建議及雪卡毒素。展覽將設於天水圍天慈邨天慈商場、新灣仔街市、北區政府合署及清水灣半島(住宅)。
The coming exhibitions will be held in April. The venues include Tin Tsz Shopping Centre in Tin Shui Wai, New Wan Chai Market, North District Government Offices and Oscar By the Sea in Sai Kung (Residential). Panels cover topics on Food Safety Ordinance, control of food temperature, natural toxins, nutrition labelling, prevention of cross contamination, 5 keys to food safety, food safety advice for pregnant women and ciguatoxins.

請點擊查看具體時間:
Please click to see the schedule:

中文 :
http://www.cfs.gov.hk/tc_chi/whatsnew/whatsnew_act/whatsnew_act_Roving_Exhibition_2015.html
English:
http://www.cfs.gov.hk/english/whatsnew/whatsnew_act/whatsnew_act_Roving_Exhibition_2015.html

食物安全中心
Centre for Food Safety

 

 

Food Alert - A batch of bottled preserved bean curd contaminated with Bacillus cereus 食物警報 -一批樽裝腐乳受致病菌蠟樣芽孢桿菌污染

Dear Sir/Madam,
 
We have issued a food alert regarding "A batch of bottled preserved bean curd contaminated with Bacillus cereus ".

 

Please check the following link for further details.

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_e.pl?record=97

 

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"一批樽裝腐乳受致病菌蠟樣芽孢桿菌污染"的食物警報。

詳情請參閱以下連結:

http://www.cfs.gov.hk/cgi-bin/cfsnew/fa/foodalert_c.pl?record=97

 

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