heating temperature (°C)

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UBISI 2004 Symposium / March 2004 / www.alp.admin.ch

New developments in heating technology for food preservation & safety

Peter U.

Peter U. Gallmann Gallmann

Chair of Research Unit Chair of Research Unit

"Food Science

"Food Science „ „ Agroscope

Agroscope Liebefeld Liebefeld - - Posieux Posieux

Swiss Federal Research Station for Swiss Federal Research Station for Animal Production and

Animal Production and Dairy Products

Dairy Products (ALP) (ALP) peter

peter. .gallmann gallmann@ @alp alp . . admin. admin . ch ch http://

http://www www. . alp. alp .admin admin. .ch ch/ /

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Developments in heating technology

! ! Food s Food s afety afety

! ! Heat load, minimal processing Heat load, minimal processing

! ! Fresh Fresh , , natural natural food food products products

! ! Shelf life Shelf life

!!

UHT UHT

!!

ESL ESL

! ! Alternatives to Heat treatment Alternatives to Heat treatment

! ! novel novel non thermal processes non thermal processes

driven by

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It is extremely fortunate that none of the major pathogens in milk form spores.

milk also contains other micro- organisms which may spoil it and shorten the shelf life of various dairy products.

Non path.

MO MO

The most resistant pathogenic organism is the tubercle bacillus (T.B.)

Pathogenic Pathogenic

MO MO

low acid food

Food safety

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Heat treatment definitions according to the Milk Hygiene Directive EU

Type of Milk Requirements

Pasteurized min. 71.7° C/15 sec.

Phosphatase : negative Peroxidase : positive High-temperature pasteurized Peroxidase : negative

UHT min. 135° C /1 sec

In-bottle sterilized no deterioration after 15 days

at 30° C

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Control of Mycobacterium avium subspecies paratuberculosis (MAP) in cow's milk

! Consensus: link between MAP intake and the Crohn’s disease has not been proved

! However control of MAP:

most possible food safety

! Most appropriate strategy at the moment:

! ! 1. Control of MAP in cattle 1. Control of MAP in cattle

! ! 2. Control during milking 2. Control during milking

! ! 3. Control during 3. Control during milk pasteurisation milk pasteurisation

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Reinvent the pasteurisation process ?

! ! The recommendation to increase the The recommendation to increase the time of pasteurisation at 71.7

time of pasteurisation at 71.7 ° ° C from C from 15 seconds to 25 seconds is based on 15 seconds to 25 seconds is based on

reports that increasing the time for reports that increasing the time for

heating at 71.7

heating at 71.7 ° ° C was more effective C was more effective than increasing the temperature of

than increasing the temperature of heating for 15 seconds.

heating for 15 seconds.

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Average pasteurisation temperature in Swiss dairies (holding time 15-25 s)

72 74 76 78 80 82 84 86

1985 1990 1995 2000 2005

h eat in g t e m p er at u re ( °C )

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Heating technology

vat pasteurisation

Guideline for pasteurisation

ALP 1999

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Heating technology

Plate heat exchanger

Plate heat exchanger Tubular heat exchanger Direct steam injection Direct steam infusion Scraped surface HE

• Ohmic heating

• Microwave heating

• Radio frequency heating

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Pasteurisation

Shelf life

14 21

0 1 2

3 4 5 6 7 8

0 1 2

Restrictions for fresh milk

Microbial quality of raw milk

quality at the end of shelf life

days Post pasteurisation

recontamination

consumption

selling

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Shelf of milk Shelf of milk

E E E x xp x p pe e ec c ct t t e ed e d d S S Sh h he e e l l l f f f L L L i i i v v v e e e ( ( ( d d d a a a y y y s s s ) ) )

T T T r r r e e e a a a t t t m m m e e e n n n t t t 4 4 4 ° ° ° C C C 1 1 1 0 0 0 ° ° ° C C C

P P P a as a s s t te t e e u ur u r ri i iz z za a at t ti i io o on n n 1 10 1 0 0 1 1 1 – – – 3 3 3

+ + + C C C e e e n n n t t t r r r i i i f f f u u u g g g a a a t t t i i i o o o n n n 1 1 1 2 2 2 4 4 4 – – – 5 5 5

+ + + M M M i ic i c c r ro r o of f f i il i l lt t tr r r a at a t ti i io o on n n 3 30 3 0 0 6 6 6 – – – 7 7 7

P P P u u u r r r e e e - - - l l l o o o w w w P P P a a a s s s t t t e e e u u u r r r i i i z z z a a a t t t i i i o o o n n n > > > 4 4 4 5 5 5 u up u p p t t to o o 4 4 4 5 5 5

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UHT technology

• Direct UHT:

steam injection / infusion

• Indirect UHT

" Sediment formation

" C. botulinus 12 D concept ?

Temperature curves for direct / indirect

UHT

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Milk consumption in Switzerland

0%

20%

40%

60%

80%

100%

2000 2001 2002

%

others UHT

pasteurized

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ESL Milk - essential characteristic from the consumer's point of view

Taste similar to the taste of pasteurised milk To be stored in the refrigerator

Shelf-life distinctly higher than shelf-life of pasteurised milk

Consequence : Heat load limitation

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ESL (Extendet Shelf Life) technology

process

! ! High Temperature Pasteurisation High Temperature Pasteurisation

! ! Micro filtration Micro filtration

! ! (Ultra (Ultra centrifugation centrifugation ( ( Bactofugation Bactofugation )) ))

•Peroxidase + or -

•shelf live up to 45 d, refrig. storage

Product

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1 10 100 1000 10000 100000 1000000

0 4 8 12 16 20 24

storage (days)

to ta l c o u n t C F U /m l

PAST ESL (BF)

Shelf life Shelf life

Total count pasteurised milk

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Effect of centrifugation (bactofugation)

1 10 100 1000 10000 100000

To ta l C ou nt

H al o t ol er an ts

En te ro co cc i

Sp or e fo rm er

Pr op io ni b ac t.

CF U/ m l

raw

BF 42 ° C

BF 52 ° C

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Micro filtrated milk

1 10 100 1000 10000 100000 1000000

0 10 20 30 40

storage (d)

p lat e co u n t ( c fu /m l)

past MF

Shelf life

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PAST BF MF HHT UHT

dir UHT ind

La ctu lo se

(m g/k g) fu ro

sin e ( m g/k g p

ro te in ) B -la

cto glo b. (m

g/l )

0 500 1000 1500 2000 2500 3000 3500

Process Peroxidase _Peroxidase neg neg . .

Peroxidase

Peroxidase pos pos . .

Heat load for different milk

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Alternatives to heat treatment

Cold techniques Electro heating technologies

•Ohmic heating

•Microwave heating

•Radio frequency heating

• Micro Filtration

• Ultrasonication

• Irradiation (ionizing radiation)

• Hydrostatic High Pressure (HHP or HPLT) technology

Pulsed electric fields

!

CAVITATION

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High pressure plant (HHP)

Containment Containment

100 100 - - 900 MPa 900 MPa

Pressure Pressure solution solution

Pressure Pressure

p p ump ump Product

Product

Cover

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Lethal effect of hydrostatic high pressure

0 1 2 3 4 5 6

0 1 5 10 15

time (min)

lo g CF U/ m l 100 MPa

300 MPa

500 MPa

700 MPa

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HHP: whey protein denaturation

0 1000 2000 3000 4000

1 5 10 15

time (min)

s o l. bet a- lac to globulin (m g/ L)

100 MPa

300 MPa

500 MPa

700 MPa

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HHP

! ! Fresh Fresh - - like quality like quality

! ! Retention of nutrients Retention of nutrients

! ! Application for acid food Application for acid food

! ! Low acid food Low acid food : combined with : combined with heat or antibacterial agents heat or antibacterial agents (spores inactivation)

(spores inactivation)

! ! Discontinuous or semi Discontinuous or semi continuous process

continuous process

! ! Expensive equipments Expensive equipments

! ! Impact on texture, structure, Impact on texture, structure, appearance, functionality

appearance, functionality

! ! Spores are not sensitive Spores are not sensitive

! ! Resistant bacteria ? Resistant bacteria ? Drawbacks

Drawbacks Opportunities

Opportunities

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PEF high-intensity pulsed electric fields

• Pulsing power delivered to the product (very fast pulses 1-100 µs duration)

• High voltage electric field(10-80 kV/cm) between a set of electrodes

PEF

Technology

• Microbial inactivation is caused by disruption of the cell membrane (irreversible

electroporation, destruction of the semi

permeable barrier and eventually lysis of the cell)

• Limited effects on spores Lethal

effects

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PEF

! ! Continuous process Continuous process

! ! Fresh Fresh - - like quality like quality

! ! Retention of nutrients Retention of nutrients

! ! Application for acid food Application for acid food

! ! Low acid food: Low acid food: combined combined process for spore

process for spore inactivation = under inactivation = under

investigation investigation

! ! Up scaling of process ? Up scaling of process ?

! ! Liquid products only Liquid products only

! ! Dependence of el. Dependence of el.

conductivity of food conductivity of food

! ! Spores are not sensitive Spores are not sensitive

! ! Potential health risk Potential health risk (electrolytic reaction) ? (electrolytic reaction) ? Opportunities

Opportunities Drawbacks Drawbacks

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Combining novel non thermal technologies (NNT) to control food quality and safety

! ! NNT and acidification: NNT and acidification:

! ! commercial application for fruit derived products HHP commercial application for fruit derived products HHP and PEF

and PEF

! ! NNT and NNT and antimicrobial antimicrobial agents agents

! ! NNT NNT – – NNT combined NNT combined (i.e. (i.e. ultrasonication ultrasonication X HPP) X HPP)

! ! NNT NNT + + creating conditions with quality preserving creating conditions with quality preserving effects (temp., pressure, atmosphere, pH

effects (temp., pressure, atmosphere, pH ) )

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Conclusion

! ! Most possible food Most possible food safety safety

!

Combining treatments = great potential for improving food Combining treatments = great potential for improving food safety and quality safety and quality

! ! Extended shelf life ( Extended shelf life ( past past + + , , MF MF , , HHT HHT , , UHT) UHT) : :

!!

local needs, consumer‘s preferences local needs, consumer‘s preferences

! ! Minimal processing: Minimal processing:

!!

heat load / h heat load / high igh treatment intensities in nonthermal treatment intensities in nonthermal processes processes

! ! Alternatives to heat = novel Alternatives to heat = novel nonthermal nonthermal processes processes

!!

No NNT = No NNT = safe enough for it‘s use alone (low acid food) safe enough for it‘s use alone (low acid food)

!!

combination with heat combination with heat treatment treatment

!!

combining nonthermal combining nonthermal technologies technologies to control food safety to control food safety