Passive versus Active Packaging

Fronteras en el envasado de alimentos:
envases activos e inteligentes
• Passive, Active, Sensing, and Smart Packaging
• Sensing Films
• Absorbing Films
• Flavor Improving Films
• Gas and Vapor Management Films
• Antimicrobial Films
• In situ Processing Films
• Bio-Active, Non-migrating Films
Tercer Simposio Internacional de Innovación y Desarrollo de Alimentos
J.H. Hotchkiss, Cornell University, USA
Passive versus
Active Packaging
• Passive Packaging: Acts as a passive barrier to
separate a product from its environment.
– Enabling technology: meet product barrier
requirements an acceptable cost.
• Active Packaging: Interacts directly with the
product and/or its environment to improve one or
more nutritional, quality or safety factors.
• Smart or Intelligent Packaging: Packaging which
“senses” a situation and provides information
such as quality, environment, location, safety,
history, etc.
1

Microbial Sensing “Smart” Films
LASER
DIFFRACTION
PATTERN
ANTIBODY GRID
Removal of Unwanted Food
Components
• Removal of aldehydes and amines from
headspace
• Immobilized Chelating Agents
2

Example: Active Control of
Lipid Oxidation in Foods
Conventional control of lipid oxidation in foods:
Additives
Antioxidant
Chelating agents
Barrier packaging/Nitrogen flushing
Active control
Absorb products of oxidation
Irreversible Removal of Amines
and/or Aldehydes
• Incorporation of activated sites onto films
• Formation of Schiff’s bases (imines)
• R-NH 2 + R’-C=O R-N=CH-R’
3

Removal of Metals
from Beverages
Fe 2+
Chelating agent
Example: In situ Processing for
Improved Flavor
• Nature makes foods such as citrus bitter to
as a df defense mechanism
• Enzymes exist which degrade the bitter
compounds
4

Immobilization of Flavorenhancing
Enzymes into
Cellulose Ester Films
• Debittering of citrus with naringinase
5

Loss of naringin from grapefruit juice after exposure to CA
film containing naringinase at 7°C
Gas & Vapor Management
• CO 2 ,O 2 , water vapor
• Ethylene
• 1-MCP as an inhibitor of ethylene
receptors
6

Equations for optimal
permeability & atmosphere
Al-Ati & Hotchkiss, 2004
7

Permeabilities and Permselectivity for Selected
Produce to Give Opt Atmosphere
(1 mil, 4°C, mL·mil/cm 2 .hr.atm)
P O2 P CO2 CO 2 /O 2
Strberry 0.245 0.26 1.1
Lettuce 0.049 0.47 9.5
Broccoli 0.032 0.07 2.2
Carrot 0.017 0.06 3.7
Apple 0.017 0.10 6.3
Celery 0.014 0.04 3.2
Cabbage 0.008 0.03 3.0
Grn Peppr 0.007 0.04 6.0
Release of MCP from Packaging
Materials
CH 2
HC = C – CH 3
8

Release of MCP from LDPE film
containing sliced apples
Antimicrobial Polymers:
Potential Uses
• Packaging (food contact films)
• Non-packaging food contact tsurfaces
– tables, filler nozzles, conveyer belts
• Personal hygiene equipment
– gloves, aprons, utensils
• Machinery surfaces
• Non-contact surfaces
– refrigeration systems, walls, floors, drains
9

Antimicrobial Polymers
Migrating: Incorporation and generation
of volatile & nonvolatile antimicrobials in
films
Non-migrating: Immobilization of
antimicrobial agents to food packaging
materials.
Example: Antimicrobial
Enzymes in Films
• Immobilization of lysozyme in cellulosic
ester films.
10

Films Containing Antibiotics
or Antimycotics: Hydrolysis of
benzoic anhydride to benzoic acid
11

Inhibition of Penicillium spp. on cheese by
LDPE containing benzoic anhydride
Nisin Impregnated Antimicrobial
Film/Paper
Hu et al 2000
Scanell et al 2000
12

Non-migrating “food additives”
When is a food additive
not a “food additive?”
Potential Non-migrating
Functional “Additives”
• Anti-microbial
• Enzymes
• Chelating agents
• Anti-oxidants
• Selective aroma sorbents/reactants
• Colors
• Surface energy modifiers
• Sanitizers
• Indicators (chemical & biological)
• Film physical and chemical modifiers
13

Immobilized Functional Food
Ingredients (Bio-active Packaging)
Enzyme
Antioxidant
Antimicrobial
Bulk
Solution or
Food
Surface
Bulk Polymer
w modified
surface
Spacer
Anchor
Active
Agent
Covalent attachment of Bioactive
Molecules to Polymers
Polymer surface
Functionalized
Polymer surface
Functionalized
Polymer surface
Biofunctionalized
Polymer surface
Goddard et al 2006
14

Surface Protein Content of PE Film Before
and After Lactase Attachment
8.00
Avera age μg protein/ /cm 2
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
a
a
a
PE PE-COOH PE-NH2 PE-GL PE-LAC PE-LAC
(SDS)
a
Film Sample
b
c
Relative Activity of Free and Film-Attached Lactase
Re elative Activ vity (%)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
4 5 6 7 8 9 10
pH Value
Free Lactase
Film-Attached Lactase
15

AFM view of modified
surface of LDPE
Antimicrobial Peptides
• Occur widely in nature.
• Typically 23 to 34 aa to 35-70 kDa proteins.
• Amphipathic and highly basic (+ charge).
• Helical structure.
• Act at cell surface.
• Permeabilize cell membrane.
16

Synthetic antimicrobial peptide
• 6K8L, leucine and lysine
• low hemolytic activity, strong antimicrobial
activity
17

Changes in OD 600nm of E. coli 0157:H7 in TSB with ()
or without () 50 μg/ml peptide 6K8L at 25°C
(b)
1.2
1
0.8
OD 600nm
0.6
0.4
0.2
0
0 20 40 60 80 100 120 140 160
Time (min)
18

Effect of peptide 6K8L on P. fluor., S. liquefac., S. typhy., E.
coli survival in buffer at 25°C for 10 min.
A.
lo og 10
CFU/ml
8
7
6
5
4
3
2
1
P.f luorescens
S. liquef sciens
S. t yphymurium
E. coli O157:H7
0 20 40 60
Peptide (ug/ml)
Effect of peptide 6K8L on S. aureus, L. mono., and B.
subtilis, K. marxianus in buffer at 25°C for 10 min.
B.
log
10
CFU/ml
7
6
5
4
3
2
1
S. aureus
L. monocytogenes
B. subtilis
K. marxianus
0 20 40 60
Peptide (ug/ml)
19

Peptide Immobilization
• PS resin bead---spacer molecule---peptide
• 345 mg (0.2 mmol) peptide/g resin
• Surface modified polystyrene (SMPS)
Immobilization on PS Beads
Peptide
Spacer
Molecule
Polymer
Bead
20

Effect of 0, 6, 10, 20, 40 mg/ml of SMPS on E. coli 0157:H7
growth in TBS at 25°C. () PS control
12
10
Log10 CFU/ml
L
8
6
4
2
0
0 5 10 15 20
Time (h)
21

Concentration (mg/ml) of SMPS required to give a 3 log
reduction in counts in buffer in 10, 30, or 60 min at 25°C
• ORGANISM 10 MIN 30 MIN 60 MIN.
• E. coli 0157:H7 8 5 4
• S. typhimurium 18 17 8
• S. liquefasciens 8 5 ND
• P. fluorescens 7 5 3
• B. subtltis 3 3 2
• L.monocytogenes 12 5 3
• S. aureus >60 57 50
• K. marxiamus 16 9 8
Conclusions
• Surfaces can be reasonably made bioactive
with commercial chemistry.
• Bioactive materials can be covalently
attached to surfaces with acceptable loss of
activity.
• Active/smart packaging materials may be
useful in foods and biomedicine.
22

"Discovery is seeing what
everyone has seen and
thinking what
nobody has thought"
-- Albert Szent-Gyogyi
23