Food Technology 2

What are 4 categories of animal origin products?

meat/meat products

milk/dairy products

fish/fish products

poultry/poultry products

What are 2 examples of meat products?

minced meats

fermented meats

why might you ferment meat

• method of preservation

• stable and highly nutritious

• extended shelf life

• safe product if handled correctly

What is the bulk of fermented meat products?

fermented sausages

what is likely to contaminate raw meat during slaughtering and butchering

• spoilage organisms

• potential pathogens

Where are fermented sausages commonly consumed?

europe - USA

What are the common meats for fermented sausages?

pork - beef

What other meats can be used for fermented sausages?

lamb - chicken - turkey - duck - buffalo

what are characteristic of specific types of fermented sausages

•Type of the meat used.

•The product formulation (amount of salt added, presence of nitrite and/or nitrate, sugar content before fermentation, spices, garlic, wine and other additives).

•Starter or natural flora is used for fermentation.

•Organisms used in the starter.

•Temperature of fermentation.

•Cooking.

•Smoking.

•Drying.

•Mould ripened.

What is the 1st ingredient added to form fermented sausages?

addition of nitrite or nitrate

What does nitrite/nitrate do to in fermentation?

suppress natural gram -ve flora

Promotes the growth of streptococci, micrococci, pediococci and lactobacilli that occur normally in meat in low numbers

What microbes do nitrite/nitrate promote?

streptococci - micrococci - pediococci - lactobacilli

How much natural fermentable carbohydrate is in raw meat?

0.1% glucose

How much fermentable carbohydrate is added to sausages?

0.3-2%

What does adding fermentable carbohydrate achieve?

sufficient lactic acid produced to give a pH of about 4.8

What does lactic acid do to water binding?

decreases water binding capacity of the meat protein

What process does lactic acid assist?

helps to assist the drying process

• bc Presence of lactic acid also decreases the water binding capacity of the meat protein.

What does the speed of fermentation depend on?

level of carbohydrates used (low carbs = slow fermentation)

What do industries use for fermented sausages?

commercial starter proteins

What are 3 benefits of using starter cultures?

• faster/more predictable drop in pH

• safer product

• earlier development of firmness

What are common starter organisms?

• lactobacillus plantarum

• pedicoccus acidlacti

• yeasts

When are micrococcus starters often used?

if nitrate but no nitrite is added

Why is nitrite essential in fermented sausages?

• prevent decolourisation

• prevent oxidative rancidity

What is the ripening process in fermented sausages?

protein is hydrolysed by microbial proteinases to give amino acids

List the 7 steps to make fermented sausages?

raw meat/fat -> mince -> mix ingredients (salt/nitrate/carbs) -> add starter -> pack into casings -> ferment -> dry and ripen

in the production of fermented sausages what happens in the raw meat plus fat stage

Contains complex microflora, including spoilage organisms, pathogens, lactic acid bacteria, micrococci

in the production of fermented sausages what happens in the mincing meat stage

inc SA for microbial activity - texture production

in the production of fermented sausages what happens in the mixing with other ingredients stage

Variable formulations Essentials are: salt, nitrate and/or nitrite and fermentable carbohydrates  

in the production of fermented sausages what happens in the addition of starter stage

Lactobacillus plantarium and Pedicoccuus spp to produce lactic acid, also Micrococcus spp may be used to covert nitrate to nitrite

in the production of fermented sausages what happens in the pack into castings stage

Traditionally animal intestine but now fibrous cellulose or reconstituted collagen from animal hides

in the production of fermented sausages what happens in the fermentation stage

Homolactic lactic acid bacteria convert glucose or other fermentable carbohydrate to lactic acid

in the production of fermented sausages what happens in the dry and ripen stage

Drying in a controlled atmosphere reduces the water content and lowers the water activity. During ripening, breakdown of fat and protein produces flavouring compounds

What happens during fermentation (sausages)?

lactic acid (converts carbs to lactic acid)

Why are fermented sausages a stable food?

low pH - low water activity

What causes low pH in fermented sausages?

lactic acid

What causes reduced water activity in fermented sausages?

salt and drying

What are microbiological problems with fermented sausages?

• 1.Growth of green or black moulds on the surface.

  2.Surface bacterial slime.

  3.Souring due to excess lactic acid production.

  4.Gassiness due to heterofermentative lactic acid bacteria.

  5.Greening of the meat pigment caused by the production of hydrogen peroxide by Lactobacillus viridans.

What causes greening in fermented sausages?

hydrogen peroxide production from lactobacillus viridans

What is the minimum heat process for low acid canned foods?

give 12 decimal reductions of C. botulinum

What is the D value for C. botulinum at 121ºC?

0.21 minutes

What is the 12D processing time for C. botulinum at 121ºC?

•(12 x 0.21 = 2.52 minutes).

What 4 issues can cause spoilage in canned foods?

• underfilling

• quality of can seal

• improper hygiene handling

• hygiene of can transport system

How does smoking food work?

wood smoke contains substances with antimicrobial activity

What antimicrobial substances are in wood smoke?

formaldhyde - higher aldehydes - phenols - methanol

give some examples of diary products (fermented milks, yoghurt, cheese)

Fermented milks

• Kefir

Yoghurt

• Set, Stirred and Drinks

Cheese

• Fermented and non-fermented

• Brined cheeses

• Soft, semi-hard, hard

What are 3 types of yoghurt?

set - stirred - drinks

What are 3 types of cheese?

fermented/non-fermented - brined cheeses - soft/semi-hard/hard

What is yoghurt?

product of bacterial fermentation of milk

What happens in yoghurt fermentation?

lactose is converted by the bacteria into lactic acid

What are the 6 steps to make set yoghurt?

raw milk -> add solids -> homogenisation -> heat treatment -> cooling/starter addition -> packaging/incubation/cooling/storage

what happens in each step to making yoghurts

What is homogenisation?

reduces size of fat globules

Why is milk heat-treated for yoghurt?

destroys pathogens - stimulates culture activity

What is a common yoghurt starter?

lactobacillus bulgaricus

What are the 6 steps for stirred yoghurt?

raw milk -> add solids -> homogenisation -> heat treatment -> cooling/starter addition -> incubation/packaging/cooling/storage

What must milk for yoghurt production be free from?

antibiotic residues

What happens if antibiotics are in yoghurt milk?

culture will not develop - pH will not drop - yoghurt will not set

What else stops yoghurt from setting?

bacteria destroyed by bacteriophages

what happens in the yoghurt when the pH decreases

• So the ph decreases

• so the yoghurt sets

• Lactobacillus and streptococcus grow and convert it to lactic acid

What are the 11 steps for cheese production?

raw milk -> pasteurisation -> starter addition -> incubation -> rennet/coagulation -> scalding -> cheddaring -> milling/salting -> moulding/pressing -> ripening -> packaging/storage

describe what happens at each step in the production of cheese

What is the pasteurisation standard for cheese milk?

72 degrees for 15 secs

What happens during cheese incubation?

fermentation - lactic acid development

What are 'early blowing' problems in cheese due to?

coliforms

What are 'late blowing' problems in cheese due to?

gas producing clostridia

what are microbial problems in cheese

• blowing

• mould growth

• bacteriophages attacking starter

What is the general food safety risk of cheese?

generally a low risk food

What causes food issues in cheese?

poor hygiene - poor pastuerisation of milk

What are uses for microbiology in the food industry?

• HACCP based systems

• risk assessment -

• raw materials/ ingredients

• hygiene monitoring

• process monitoring

• finished products

• crisis management

how is microbial info essential for building a HACCP plan

•Raw materials and associated sources of supply

•Production flow chart

•Process points that influence the growth, death, survival or contamination with micro-organisms

•Consequences of failure of any process stage

•CCPs determination and establishment of monitoring and reviewing systems

what is taken into account for risk assessments

Hazard identification

Hazard characterization

Exposure assessment

Risk characterization

whats the difference between a hazard and a risk

A hazard is something that can cause harm

A risk is the chance, high or low, that any hazard will actually cause somebody harm

list some pathogens found in rice

bacillus cereus

list some pathogens found in poultry and milk

campylobacter jejuni

list some pathogens found in veg, fish, peanuts, hazelnuts and honey

Clostridium botulinum

list some pathogens found in veg, red meat

Clostridium perfringens

list some pathogens found in red meat, fruit, milk and milk products, salad veg

E. Coli

list some pathogens found in milk (cheese) and meat products

Listeria monocytogenes

list some pathogens found in coconut, pepper, poultry, meat, chicken, eggs, fruit and fruit juice

Salmonella spp.

list some pathogens found in shellfish

Vibrio parahaemolyticus

What things can be monitored for hygiene?

Swabs

• Surfaces, pipes, equipment

Solid or liquid samples

• Soil (agriculture)-

• •Rinse water

Personnel

• Hand-swabbing

• Hand-rinsing

Air

• Exposure plates

• Air sampling machines

give some examples for assessing these processing stages

• handling

• packaging

• product

• transfer systems

• chill/ freezer stores

how can finished products be tested

Conformance to microbial criteria

Product shelf life evaluations

Microbiological challenge testing

how are microbial criteria drawn up

Microbial criteria are drawn up in relation to specified foods and consist of:

1.A statement of the microorganisms and/or their toxins of concern to the food.

2.The methods to be used for their detection and/or enumeration.

3.A sampling plan.

4.The microbiological limits to be used in assessing the results

5.Guidance for interpreting the results.

• Number of sample units that should conform to the limits.

What are components of microbial criteria for foods?

• limits for

  • pathogens

  • microbial toxins

  • indicator micro-organisms

  • spoilage micro-organisms

• frequency of sampling

• A clear description of the food/sample type to be examined.

• A clear description of the relevant microorganisms or toxins in concern.

• An unambiguous sampling plan

what is a sampling plan

A sampling plan is a statement of the criteria of acceptance applied to a lot based on appropriate examinations of a required number of sample units by specified methods

what do sampling plans consist of

It consists of a sampling procedure and decision criteria

what can a sampling plan be

A sampling plan may be a two-class or a three-class plan

What 3 descriptive components are needed for microbial criteria?

clear description of food - clear example of relevant micro-organisms/toxins - unambiguous sampling plan

what does a 2 class plan consist of

A two-class plan consists of the following specifications: n, c and m

What do 'n' 'c', and 'm' mean in two-class sampling?

,n=number of samples - c=max acceptable units exceeding m - m=max bacteria/gram

What is the difference in three-class sampling?

A three-class plan requires n, c, m, and M (adds 'M')

What does 'M' represent in three-class sampling?

seperate marginally acceptability from unacceptability

What happens if a sample value is at or above M?

whole batch will be rejected

in this 2 class sample would the batch be accepted or rejected

One of the samples above m for E. coli

Two above for S. aureus

Listeria and Salmonella ok

so batch accepted

in this 3 class sample would the batch be accepted or rejected

For three class sampling M is introduced

M = 1000 cfu/g for E. coli and S. aureus

• batch rejected

when would you use 2 and 3 class sampling

•For presence or absence tests we use a two-class plan.

•For count or concentration tests we use a three-class plan.

What regulation covers microbiological criteria for foods?

EC regulation 2073/2005

What factors are involved in shelf life evaluation?

•Deterioration in specific organoleptic qualities (flavour, aroma, appearance, texture).

•Microbial growth (bacterial pathogens, bacterial indicator organisms and spoilage organisms.

what does shelf life evaluation of perishable chilled products involve

storage of finished products at ‘specified’ and at abuse temperatures.