acid decontamination

1. Microbial Decontamination by
acids
Presented by
Princess Monica PS
2019671804
PhD –FPE
FPE 606 ADVANCES IN FOOD PROCESS ENGINEERING
Course Teacher
Dr. V. R. Sinija
Professor and Head
IIFPT
Thanjavur
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2. Outline
 Effects of acid treatment on sensory properties
 Mode of application
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3. Introduction
 Decontamination with organic acids has been frequently associated
with colour and odour/flavour changes of treated foods.
 Colour deterioration has been observed in acid-treated.
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4. Effects of acid treatment on
sensory properties
1. Effects on colour
a) Ruminants
 When many blood spots are present acid treatment, particularly at high
concentrations, may result in blood coagulation and consequently in the
appearance of rusty brown-black spots, as was confirmed in experiments with
beef, veal and buffalo carcasses .
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5. 5
Acid treatment Results references
1 % lactic acid spray slight but reversible discoloration of beef
carcasses.
Snijders et al.
immersion of diced
beef in various acetic
and acetic/formic
acid solutions
immersion in an acetic acid solution at higher
concentrations than 0.6% resulted in discoloration.
Bell et al
1 % lactic acid at
20°C
no colour effects on beef cuts from
vacuumpackaged
Greer and Dilts
formic, acetic and
propionic acid as
sanitisers for beef,
and found that the
microbiologically most effective solutions, 2%
formic acid or 1 % formic plus 1 % acetic acid,
produced brown off-colours within seconds after
spraying, a phenomenon seen at formic acid
concentrations of 0.5% and higher.
QuarteyPapafio
et al.

6. (b) Pork.
1 % lactic acid, not result
in discoloration of the
carcass, Prasai et al. even
for hot (55°C) sprays.
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Acid treatment Results References
sprayed pork
carcasses with
various
concentrations of an
acetic-propionic acid
solution mixed in
60:40ratio (w/w
excessive darkening
and discoloration on
all lean cut surfaces
when applying the
3.0 M solution, which
was attributed to the
propionic acid.
Reynolds and
Carpenter
2.40% lactic acid an irreversible
discoloration of pig
carcasses especially
in the thorax,
cavities and locations
in which lactic acid
was collected
Labots et al.
1.5% lactic acid minimal effect on
colour.
Snijders et al
pork loins, spray-
washed and sanitised
with 2% acetic acid
less pinkish-red and
had a less desirable
colour
Cacciarelli et al.

7. 1. PSE(pale, soft, and exudative)
2. Normal
3. DFD(dark, firm, and dry)
pork.
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1 2
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8. (c) Poultry.
 Mountney and O'Malley - broilers treated with acetic-, adipic- and succinic- (but not with lactic) acid
of various concentrations caused the carcasses to whiten slightly.This effect was more pronounced
with acetic- than with succinic acid.
 Dresel and Leistner reported a slight discoloration after treating chicken carcasses with 2.8% acetic,
1.8% lactic, 0.25% citric and 0.1 % ascorbic acid solutions.
 Stern et al reported carcass discoloration when broilers were treated with 1 % lactic acid at 5°C,
also observed by Van der Marel et al. at 2% lactic acid and higher.
 Mulder et al. (using 1 % lactic acid) and Cudjoe and Kapperud -(using 2% lactic acid) did notice
bleaching (suggested by Mulder et al. to possibly be the result of the natural catalase activity of skin
and blood, releasing oxygen after treatment) or 'graying‘ of broiler carcasses, this discoloration
reverted to normal after 24 h.
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9. (d) Variety meats.
 When decontaminating variety meats by immersion in acid solutions the surface may discolour,
depending on the nature of the tissue.
 High concentrations are possible, for instance, with tongues, where surfaces will be peeled off in the
course of preparation .
 However, livers discolour after immersion in lactic acid concentrations higher than 0.20% . Calf brain
exhibits off-colours at 1.25%, whereas lower concentrations do not provide adequate decontamination
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10. 2. Effects on flavour and odour
a) Ruminants.
 Woolthuis and Smulders assessed the effects of 2 and 4% lactic acid sprays (followed by 2 h of
incubation) of fresh veal chops on the flavour after 3 min of frying in butter. Only the 4% lactic acid
spray resulted in panel flavour scores different from the untreated controls.
 Gill and Penney found even 5% lactic acid had no significant effect on flavour and odour and vacuum-
packaged lamb after storage periods of 3, 6, 9 and 12 weeks.
 In a study by Bell et al. panelists identified flavour differences between baked ground beef prepared
from diced beef, that had been immersed either in 1.2% acetic acid or distilled water. Treatment with
0.6% acetic acid did not lead to flavour differences.
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11. (b) Pork.
 Reynolds and Carpenter observed slight residual off odours of pork carcasses treated with
2.32 M acetic acid or 1.67 M acetic/ 1.36 M propionic acid solutions.
 Sirami et al. found impaired flavour in meat products prepared from diced pork and raw
ham treated with an acid mixture of acetic-, lactic-, citric- and tartaric acid.
 Gauthier and Jacquet reported vinegar-like off-flavours in garlic sausage prepared from
diced pork that had taken up 1.5 klkg acetic acid; when pork was processed into pate such
differences were not noticed.
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12. (c) Poultry.
 Mountney and O'Malley noticed that the strong odour of broiler carcasses treated with
acetic acid was offensive, whilst the odours associated with adipic- and succinic acid,
although detectable, were not unpleasant. No adverse effects of lactic acid on flavour
and odour were reported.
 Mulder et al. found no off-odour of broiler carcasses after 1 % lactic acid treatment.
 Van der Marel et al. established that lactic acid accumulated in the skin of broilers with
no increase in acid in the underlying muscle tissue. Concentrations up to 5% lactic acid
produced no flavour differences in grilled legs.
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13. (d) Variety meats.
Visser et al. did not observe off-odours of veal tongues after immersion in
3% lactic acid.
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14. Effects on drip loss
 Offer and Trinick stated that lowered intracellular pH may cause myofibrillar shrinkage
and may thus result in drip loss.
 Mendonca et al. measured the percent exudate from pork chops in the course of 4
weeks of refrigerated vacuum storage and observed increases in drip loss in all chops
immersed in acid solutions, particularly those solutions (3% acetic acid/3% sodium
ascorbate, 3% acetic acidl1.5% sodium chloride and 1 % acetic acid/1 % lactic acid)
that caused lower pH values.
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15. Mode of application of acids
1. Spraying and spray cabinets
 Spraying is the most common way of applying acids to
carcasses. For experimental purposes, hand-held spray
devices have been used .
 Of the physical parameters, spray pressure and flow rate,
nozzle type and configuration and angle of the spray
seem to be particularly relevant.
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16.  In the Netherlands a prototype carcass spray unit was designed for a veal slaughter
plant (Smulders et al., ) Sanitising relies on the combination of mechanical removal by
water sprays of blood and dirt and decontamination by hot water or acid.
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17. 17
Features of prototype spray unit
1.8 fan type nozzles spraying at 202.5
kPa, is moved around the carcass.
2.lower ring sprays water at a 30°
downward angle

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19. Entry doors to enclosed spray wash cabinet.
The two doors open to permit the entry of a carcase.
Exit doors
The spray wash cabinet is designed for a single carcase
at a time to minimise cross contamination.
The chain speed is 7.5 carcasses/minute.
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20. Sprays at the surface of the carcass for three
seconds at 16 bar pressure.
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21.  The spray carcass washer is made of stainless, acid-resistant materials.
 Carcasses are washed by spraying from nozzles placed on both sides of the
washer.
 Water nozzles produce mist which reaches deep into the carcasses. The
suspended spray carcass washer is designed for washing hens and chickens in
poultry processing lines.
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22. Carcass during spray treatment
Spray system configuration
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23. Sub primal Spray Cabinet
 It was designed to use a conveyor belt
delivery system consisting of flexible bands
that could support a large subprimal
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24. 2.Immersion
 Variety meats and (sub)primals may be decontaminated by immersion for a certain
period.
 In this procedure organic acids very effectively reaches all locations, possibly even
including the interior of organs such as the liver via the bile ducts .
 Immersion may not prove to be very cost-efficient. For instance, Dorn et al. found
that immersion of large numbers of Salmonella contaminated broiler carcasses in
solutions containing various acid decontaminants was not very successful.
 the immersion of pork loins in acid solutions has been reported to be effective for
pork loins , procedure will prove cost-efficient under commercial circumstances.
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25. Screw type
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26. Other methods
 Lactobacilli produce antibacterial agents (bacteriocins) as by-products of their
metabolism. Consequently, starter cultures of lactic acid bacteria have been applied as in
situ lactic acid producers, particularly in comminuted meats.
 Gill and Penney [106] reported that vacuum-packaged lamb treated with a Lactobacillus
culture and stored for 9 weeks at -O.5°C had lower odour and flavour scores. Extended
storage (12 weeks) resulted in the development of off-colours and unacceptable 'dairy'
flavours. Recently, attempts have been made to apply isolated bacteriocins to
contaminated beef carcass surface tissue using a pilot scale spray washer.The results of
this work look very promising (Dr Gregory R. Siragusa, 1994, personal communication).
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27. References
 Australian Meat Processor Corporation. 2015. Assessing the effectiveness of a
carcasse hot water decontamination cabinet in small stock processing
 G.W. Gould .1995. New Methods of Food Preservation
 Kelly A . 2016.Comparison Of Electrostatic Spray, Spray, Or Dip Using Lactic Acid,
Peroxyacetic Acid, Or Beefxide™ On The Effects Of Color And Aerobic Plate Counts
 D. V. Bourassa .2016.Carcass orientation and drip time affect potential surface water
carryover for broiler carcasses subjected to a post-chill water dip or spray1
 M.K. Youssef.2011. Effects of spray volume, type of surface tissue and inoculum
level on the survival of Escherichia coli on beef sprayed with 5% lactic acid
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28. Thank you
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