Meat Processing 1Common preservation techniques

A webinar presented by:

Dr Andy Bowles

Attendee Notes

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Meat Processing 1Common 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

MeatPreparations

Burgers

Sausages

Kebab

Cured Meatpieces

Cured rawmeat

Curedcooked meat

Raw-cookedmeat

Frankfurters

Meat loaf

Pre-cookedcooked

products

Blackpudding

Liversausage

Fermentedsausages

Salami

Driedproducts

Biltong

Jerky

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General principles

Chemical Composition of meat

PRODUCT WATER PROTEIN FAT MINERALSBEEF (LEAN) 75.0 22.3 1.8 1.2BEEF (CARCASS) 54.7 16.5 28.0 0.8PORK (LEAN) 75.1 22.8 1.2 1.0PORK (CARCASS) 41.1 11.2 47.0 0.6CHICKEN 75.0 22.5 0.9 1.2FRANKFURTER 63.0 14.0 19.8 0.3LIVER SAUSAGE 45.8 12.1 38.1LIVER PATE 53.9 16.2 25.6 1.8SALAMI 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

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Heat Treatment

Heat treatment

Heat treatment of processed meat productsserves 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

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Heat treatment

Some products subject to two initial heattreatments Raw materials pre-cooked Further processed For example black pudding.

Important to be clear about the nature of heattreatment on inspection.

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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 microorganisms: Results in % kill / unit time

Characterised by “D”, “Z” and “F” values.

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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

Surv

ivin

g Sp

ores

Heating Time (Min)

D Value 5 Mins

D Values

This is the time taken to reduce micropopulation 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

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Heat Resistance of Food PoisoningBacteria

Organism D Value (seconds)Campylobacter sp D55 = 60

Salmonella sp D60 = 34.8

Listeria sp D 71.7 = 3.3

Staph. Aureus D60 = 120 – 2000D71.7 = 4.1

Clostridium botulinum

Escherichia coli

D121 = 12.6D62.8 = 7.8

Z Value Change in ºC required to

bring about a 10 foldchange in D

aka Temperaturecoefficient of destruction

D and Z valuescharacterise the heatresistance of an organism 1

10

100

1000

90 110 120 130

D v

alue

s

Temperature

Z Values

Destruction of E.coli o157 in burgersACMSF 2007

Temperature °C ACMSFRecommendation

6 D reductionZ 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

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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 controlidentified microbial hazards: Salmonella spp E.coli o157 Listeria spp Staph.aureus etc.

Where necessary: C.botulinum

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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 consideredhigh: 70°C for 2 minutes or equivalent

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Lowering water activity

aw - Water Activity

Measure of amount of liquid water availablefor microbial growth

Pure water = 1.0 Presence of solutes = <1.0 Enables prediction of possible bacterial

growth in food Bacteria generally require high aw for growth

Typical aw values for meat products

PRODUCT aw RANGEFRESH MEAT 0.99 (0.99 – 0.98)COOKED HAM 0.97 (0.98 – 0.96)RAW – COOKED SAUSAGES 0.97 (0.98 – 0.93)LIVER SAUSAGE 0.96 (0.97 – 0.95)BLOOD SAUSAGE 0.96 (0.97 – 0.86)RAW FERMENTED HAM 0.92 (0.96 – 0.80)RAW FERMENTED SAUSAGES 0.91 (0.96 – 0.70)DRIED MEAT 0.70 (0.90 – 0.60)

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aw values for limiting microbial growthMICROORGANISM aw

Pseudomonas 0.93E.coli 0.93Salmonella spp 0.91 – 0.95Listeria 0.93Clostridium botulinum (proteolytic) 0.94Clostridium botulinum (non-proteolytic) 0.97Clostridium perfringens 0.93 – 0.95Bacillus species 0.90 – 0.95Staph aureus 0.86 – 0.90Most yeasts 0.87 – 0.90Most moulds 0.80 – 0.85

Reduction of pH

Effects of pH on microbial growth Acidophile Lactobacillus acidophilus

Neutrophile Salmonella spp

Alkaliphile Nitrobacter spp

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Reduction of pH

PRODUCT pHRaw fermented sausage 4.5 – 5.2Beef 5.4 – 6.0Pork 5.5 – 6.2Canned meats 5.8 – 6.2Biltong 5.8Ham 5.9 – 6.1Black pudding 6.5 – 6.8

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Typical pH values for some foodspH Range Food pHLow acid (pH 7.0 –5.5)

Medium acid (pH 5.5 – 4.5)

Acid (pH 4.5 – 3.7)

High acid (pH <3.7)

MilkCheddar CheeseBaconRed MeatHamPoultryFishButterBreadCottage cheeseGreen beansBananasMayonnaiseTomatoesCanned pickles, fruitjuiceSauerkrautCitrus fruitApples

6.3 – 6.55.95.6 – 6.65.4 – 6.25.9 – 6.15.6 – 6.46.6 – 6.86.1 – 6.45.3 – 5.84.54.6 – 5.54.5 – 5.23.0 – 4.14.03.5 – 3.93.1 – 3.33.0 – 3.52.9 – 3.3

Use of chemical preservatives

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Effects of osmotic pressure on microbial growth

Typical NaCl levels in some Foods

Food NaCl (%)BaconHam (canned)Ham (raw)Smoked FishCheddar CheeseRaw FishRaw Meat –BeefLambChickenTurkey

3.0 – 4.83.22.6 – 3.61.9 – 4.81.6 – 1.80.3

0.20.20.20.2

Use of modified atmospheres

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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

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Modified Atmosphere Packaging (MAP)

Food preservation technique whereby: the composition of the atmosphere surrounding

the food different from the normal composition ofthe 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 manypsychrotrophic bacteria

O2

inhibits anaerobes, develops bright red colour inmeat

N2

inert, used as a filler to prevent collapse ofpackaging.

Effects of MAP on Micro-organisms

CO2 Increases lagphase

Gram -ve moresensitive to CO2

CO2 can inhibitgrowth of spoilagemoulds

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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 Special equipment

required Inherent food safety

risks

Food Safety Concerns

Food Safety Concerns

Absence of oxygen Growth of Clostridium botulinum favoured Listeria monocytogenes, Staph aureus

Primary Food Safety Concern: Increased probability of C.botulinum toxin

formation before spoilage bacteria make productunacceptable to the consumer

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Clostridium botulinum

Psychrotrophic C.botulinum Important in VP/MAP chilled foods

Types B,E,F can grow at 3.3°C As shelf life increases - more time to grow Toxin formation increases with temperature

Characteristics of Group I and IIC. botulinum.Characteristic* Group I

(proteolytic)(A & B)

Group II(non-proteolytic)(B, E & F)

Minimum temperature forgrowth (oC)

10 3.3

Maximum Temperature forgrowth (oC)

48 45

Inhibitory pH 4.6 5.0

Inhibitory NaCl concentration(%)

10 5

Inhibitory aw 0.94 0.97

*Value when other conditions are optimal for growth

Assessment of Risk from C.botulinum

Basic principles: C.botulinum must be present Inadequate processing or unprocessed product Product must support growth and toxin formation Intrinsic Extrinsic

Product must be ingested.

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Vacuum Packaging of Red Meat

Commonly used for distribution and storage ofprimal cuts of meat.

Cut will appear dark purple. Upon opening pack myoglobin will be oxygenated to

oxymyoglobin (Bright red). Vacuum packed primal cuts of beef with normal

pH can be stored for several weeks at 0oC Not suitable for comminuted meats

MAP- Gas Flushing of red meat

Air is removed from the pack and replacedwith a control atmosphere. Inhibits the growth of aerobic spoilage bacteria

such as Pseudomonas spp. Lactic acid bacteriapredominate.

Raw red meat attractive red colour due to theformation of oxymyoglobin

Effectiveness is dependant on goodtemperature control and good quality meat

Equipment required is expensive

Typical controlling factors

Temperature No growth of C.botulinum at 3°C Heat treatment 90°C for 10 minutes

pH 5 or less throughout food

Salt level 3.5% throughout food

Water availability (aw) 0.97 or less throughout food

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Listeria control strategies

Meat products vulnerable to the outgrowth ofListeria monocytogenes which may be present inthe environment.

FBOs should be encouraged to: Undertake environmental investigation, based on HACCP

principles, to determine the likely occurrence of listeriaand

introduce effective controls to prevent the contaminationof finished products.

This investigation should include, but not be limited to, aconsideration of the use of environmental swabs.

Listeria control

Guidance issued byFSAI

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References

http://www.fao.org/docrep/010/ai407e/AI407E00.htm

Questions?

Dr Andy Bowles FIFSTSpecialist food law solicitor

andy.bowles@abcfoodlaw.co.ukwww.abcfoodlaw.co.uk

01603 274486

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