Effect of Direct CO2 Addition on the Safety

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Effect of Direct CO2 Addition on the
Safety Quality of Neutral pH
Dairy Products ? Product Examples Post
versus Pre-pasteurization Processing aid J.H.
Hotchkiss, J.H. Chen, B. Andeberhan, C. Loss
N.E. Dairy Foods Research
Center
Cornell University
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Possible Effects of CO2 on Microorganisms
Displace O2 Lower pH Inhibit
function/metabolism - Intra-cellular pH -
Membrane fluidity - Inhibit metabolic
pathways ? Affect thermal resistance
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Adding CO2 to Dairy Foods
Post-pasteurization - Shelf life
extension - Sensory threshold - Process
control - Package barrier -
Regulatory status Pre-pasteurization -
Raw storage - Transportation -
Processing aid - Removal of residual CO2
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Factors Affecting Shelf Life with Directly Added
CO2 CO2 Concentration (dissolved) -
minimum 4.5 mM (200 ppm) - maximum 45 mM
(2000 ppm) Storage Temperature - lower
more effective - 21 small effect
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Factors Affecting Shelf Life with Directly Added
CO2 (cont.) Initial microbial load/type -
lt 10 1 cfu/ml maximum shelf life - gt 10 4
cfu/ml maximum difference Barrier properties
of package - Continuous from glass to no
barrier Product characteristics - Growth
medium - Fat content - Sensitivity
to spoilage - pH
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Products Evaluated with CO2 Whole
pasteurized milk 2 milk in pouches
2 milk in BM PB containers Ice cream
mix Cottage cheese Concentrated raw
milk 2 milk with C. bot. Whole
milk with listeria Yogurt
published
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General Protocol for CO2 Evaluation Product
inoculated (uninoculated) Add
CO2 Control (Process) (Process)
Package Package Store (6.1
C) Store (6.1 C) Evaluate Evalua
te SPC SPC Gm-
Gm- CO2 CO2 pH
pH YM YM Sensory
Sensory
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Post-Pasteurization Addition to Milk
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Single Serve Milk

• Material PET, HDPE, PB, Pouch
• Light induced flavor vitamin loss
• Effects of barrier (including closure)
• Flavor/odor absorption
• Opening size, finish, and closure
• Labeling
• Unit cost
• Marketing

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Factors Affecting Milk Microbiological Shelf Life

• Raw milk quality
• Thermal processing parameters
• Recontamination level
• numbers and types of m.o.
• Filling
• Storage temperature
• Barrier properties of container (?)

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Effect of CO2 on Microbial Growth in Glass, PET
and HDPE

• P. fluorescens inoculated milk
• 16 oz, glass, PET, HDPE, w and w/o foil induction
  sealed membranes
• Evaluate SPC, odor, appearance

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Single-serve milk and CO2 in HDPE and PET bottles

• CO2 increased time to reach 106 cfu/ml by
  approximately 3-5 days at 43?F (inoculated)
• No observable difference between PET and HDPE
  without CO2
• PET somewhat (1 day) better than HDPE with CO2
• No observable effect of induction sealed foil
  under lid

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Shelf Life Estimates for Dairy Products with
Directly Added CO2 and Stored at 6.1C
commercial experience
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Industry Opportunities Transportation and
short-term storage of raw milk Processing
aid in milk to be used in manufacturing
Concentrated milk storage and transport
Institutional packs Single serve milk and
yogurt
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CO2 as a Processing Aid

• Addition-- Process-- Remove by Vacuum
• Temporary pH reduction (removable acid)
• Microbial inhibition
• Examples Effect on concentrated raw milk and
  pasteurization

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CO2 as Processing Aid in Pasteurization
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Conclusions

• Low level CO2 inhibits spoilage organisms
• Shelf life can be extended in both acidic and
  neutral products
• Potential exists for CO2 as process aid

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THE END