View
8
Download
0
Embed Size (px)
Meat Processing 1 Common preservation techniques
A webinar presented by:
Dr Andy Bowles
Attendee Notes
Page0
1
Meat Processing 1 Common preservation techniques
Dr Andy Bowles
Introduction
In this webinar I will discuss: General principles of preservation Common techniques used in the meat industry Heat treatment Lowering of water activity (aw) Reduction of pH Use of chemical preservatives Use of modified atmospheres
Types of meat product
Meat Preparations
Burgers
Sausages
Kebab
Cured Meat pieces
Cured raw meat
Cured cooked meat
Raw-cooked meat
Frankfurters
Meat loaf
Pre-cooked cooked
products
Black pudding
Liver sausage
Fermented sausages
Salami
Dried products
Biltong
Jerky
Page1
2
General principles
Chemical Composition of meat
PRODUCT WATER PROTEIN FAT MINERALS BEEF (LEAN) 75.0 22.3 1.8 1.2 BEEF (CARCASS) 54.7 16.5 28.0 0.8 PORK (LEAN) 75.1 22.8 1.2 1.0 PORK (CARCASS) 41.1 11.2 47.0 0.6 CHICKEN 75.0 22.5 0.9 1.2 FRANKFURTER 63.0 14.0 19.8 0.3 LIVER SAUSAGE 45.8 12.1 38.1 LIVER PATE 53.9 16.2 25.6 1.8 SALAMI 33.9 24.8 37.5
Common processes used by meat industry
Heat treatment Lowering of water activity (aw) Reduction of pH Use of chemical preservatives Use of modified atmospheres
Hurdle technology
Page2
3
Heat Treatment
Heat treatment
Heat treatment of processed meat products serves two main purposes: Enhancement of desirable texture,
flavour and colour Reduction of microbial content Ready to eat Appropriate shelf life
Heat treatment
Can be two-stage heat treatment: As part of processing Prior to consumption
Frankfurters raw-cooked sausage Initial process used to achieve desired: Texture Flavour Colour
Page3
4
Heat treatment
Some products subject to two initial heat treatments Raw materials pre-cooked Further processed For example black pudding.
Important to be clear about the nature of heat treatment on inspection.
(
Thermal processing
Different degrees of preservation: Sterilisation Complete destruction of micro-organisms 121°C for 15 mins
Commercial sterility All pathogens, toxins and spoilage bacteria destroyed. Some thermoduric survivors
Pasteurisation Kills pathogens Extends shelf life
Blanching Inactivates key enzymes Reduce bacterial load
Effect of Heat on Micro-Organisms
Application of heat sufficient to kill micro organisms: Results in % kill / unit time
Characterised by “D”, “Z” and “F” values.
Page4
5
D Values
Decimal reduction time Varies for different
organisms Quoted at a particular
temperature ie “D121” Cells die more rapidly
at higher temperature
1
10
100
1000
0 5 10 15
Su rv
iv in
g Sp
or es
Heating Time (Min)
D Value 5 Mins
D Values
This is the time taken to reduce micro population by 90% Higher “D” Value indicates higher heat resistance
NOTE: More Micro orgs in raw material, longer it will take to get to desired level
D Values
Can be expressed as 5D, 8D or 12 D etc 8D process will reduce numbers by 100,000,000 5D and 8D commonly used, 12D used for low acid canning
Page5
6
Heat Resistance of Food Poisoning Bacteria
Organism D Value (seconds) Campylobacter sp D55 = 60 Salmonella sp D60 = 34.8 Listeria sp D 71.7 = 3.3 Staph. Aureus D60 = 120 – 2000
D71.7 = 4.1 Clostridium botulinum
Escherichia coli
D121 = 12.6 D62.8 = 7.8
Z Value Change in ºC required to
bring about a 10 fold change in D
aka Temperature coefficient of destruction
D and Z values characterise the heat resistance of an organism 1
10
100
1000
90 110 120 130
D v
al ue
s
Temperature
Z Values
Destruction of E.coli o157 in burgers ACMSF 2007
Temperature °C ACMSF Recommendation
6 D reduction Z 6°C
60 45 mins 93 mins
65 10 mins 13.6 mins
70 2 mins 2 mins
75 30 secs 18 secs
80 6 secs 3 secs
Page6
7
F Value
Total time/temp received by a food.
F0 = F121 Number of minutes at 121°C to heat food
Minimum Safe Process “Botulinum Cook” Applied to low acid canned foods Necessary to achieve 12D reduction of
Clostridium botulinum spores At 121ºC D value for Cl.botulinum is 0.21
minutes 12 x 0.21 = 2.52 minutes (ie F0 of 3.0) F0 values will vary according to food type etc Sufficient margin of safety built in.
Food safety controls: Thermal Process
Thermal process must be adequate to control identified microbial hazards: Salmonella spp E.coli o157 Listeria spp Staph.aureus etc.
Where necessary: C.botulinum
Page7
8
Food safety controls: Thermal Process
Where risk from C.botulinum considered high 90°C for 10 minutes or equivalent
Where risk from C.botulinum not considered high: 70°C for 2 minutes or equivalent
Page8
9
Lowering water activity
aw - Water Activity
Measure of amount of liquid water available for microbial growth
Pure water = 1.0 Presence of solutes =
10
aw values for limiting microbial growth MICROORGANISM aw
Pseudomonas 0.93 E.coli 0.93 Salmonella spp 0.91 – 0.95 Listeria 0.93 Clostridium botulinum (proteolytic) 0.94 Clostridium botulinum (non-proteolytic) 0.97 Clostridium perfringens 0.93 – 0.95 Bacillus species 0.90 – 0.95 Staph aureus 0.86 – 0.90 Most yeasts 0.87 – 0.90 Most moulds 0.80 – 0.85
Reduction of pH
Effects of pH on microbial growth Acidophile Lactobacillus acidophilus
Neutrophile Salmonella spp
Alkaliphile Nitrobacter spp
Page10
11
Reduction of pH
PRODUCT pH Raw fermented sausage 4.5 – 5.2 Beef 5.4 – 6.0 Pork 5.5 – 6.2 Canned meats 5.8 – 6.2 Biltong 5.8 Ham 5.9 – 6.1 Black pudding 6.5 – 6.8
(
Typical pH values for some foods pH Range Food pH Low acid (pH 7.0 –5.5)
Medium acid (pH 5.5 – 4.5)
Acid (pH 4.5 – 3.7)
High acid (pH
12
Effects of osmotic pressure on microbial growth
Typical NaCl levels in some Foods
Food NaCl (%) Bacon Ham (canned) Ham (raw) Smoked Fish Cheddar Cheese Raw Fish Raw Meat – Beef Lamb Chicken Turkey
3.0 – 4.8 3.2 2.6 – 3.6 1.9 – 4.8 1.6 – 1.8 0.3
0.2 0.2 0.2 0.2
Use of modified atmospheres
Page12
13
Vacuum and modified atmosphere packaging
MAP - a definition “packaging of a food product in something other than air” Includes:
vacuum packaged (VP) modified atmosphere packaged (MAP) controlled atmosphere packaged (CAP) gas packed/gas flushed sous-vide Also any other condition which will result in a similar reduction of
oxygen e.g. deep-filled or hermetically sealed products
Vacuum Packing (VP)
Food Preservation technique where: atmospheric air is removed vacuum maintained by integrity of pack
Vacuum Packing (VP) Advantages
Increased shelf life Equipment relatively
inexpensive Freshness and flavour
maintained Moisture retained Rancidity reduced Infestation eliminated Wastage reduced Portion control and
presentation
Disadvantages Temperature control
required Inherent food safety risks Not suitable for soft
products Undesirable colour
changes in red meat
Page13
14
Modified Atmosphere Packaging (MAP)
Food preservation technique whereby: the composition of the atmosphere surrounding
the food different from the normal composition of the air.
Process involves Removal of air Replacement with mixture of Carbon dioxide Nitrogen Oxygen
Gas mixture varies for type of food
Gases for MAP
CO2 has biostatic properties against many
psychrotrophic bacteria O2 inhibits anaerobes, develops bright red colour in
meat N2 inert, used as a filler to prevent collapse of
packaging.
Effects of MAP on Micro-organisms
CO2 Increases lag phase
Gram -ve more sensitive to CO2
CO2 can inhibit growth of spoilage moulds
Page14
15
Advantages / Disadvantages of MAP
Advantages Increased shelf life Reduced distribution
costs High quality product Reduced need for
additives Minimisation of waste
Disadvantages Expensive Temperature control
required Different gases required
per product Spec
