Joseph H. Hotchkiss is a Professor in the Institute of Food Science and the Institute for Comparative and Environmental Toxicology at Cornell UniversityHe teaches and directs an active research program in food packaging, food safety and quality and toxicology. He joined the faculty after serving as a Public Health Fellow atthe US Food and Drug Administration. He is a former member of the Food Chemicals Codex at the National Academy of Sciences and of the WHO/FAO Joint Expert Committee on Food Additives. He also is a former member of FDA's Food Advisory Committee.He teaches Introductory Food Science, Concepts in Product Development, and Food Packaging. He is a co-author of the 5th edition of the widely used text Food Science He has also served on the editorial board of such journals as the Journal of Food Protection, Journal of the Science of Food and Agriculture, and Reviews in Food Critical Science and Nutrition.
Antimicrobial Nano-Biotechnologies for Flexible
Bioactive Packaging
• Rationale• General Approach• Examples
J.H. Hotchkiss Cornell University
“Nano” as applied to polymeric materials
• Particle size and barrier: 1 to 100 nm• Unique physical/chemical properties:
As particles are reduced in size their physical properties change.
• Nano methodology: Use of nano-technologies to affect macro properties
Immobilized Functional Biologically Active Molecules
Bulk Polymer
Antimicrobial
Enzyme
Antioxidant
Spacer Anchor
Active Agent
Bulk Solution or Product Surface
Rationale• Provide functionality to polymer
surfaces– Antimicrobial compounds – Enzymes (in situ processing)– Antioxidants– Odor control– Barrier control– Controlled release– Indicating films
Odor Removal: Irreversible Removal of Aldehydes
• Incorporation of activated amines into films
• Formation of Schiff’s bases (imines) • R-NH2 + R’-C=O R-N=CH-R’
Flavor Enhancement: Immobilization of Naringinase
in Cellulose Ester Films
• Debittering of naringin in citrus
Antimicrobial Films
Migrating: Incorporation and generation of volatile & nonvolatile antimicrobials in films
Non-migrating: Immobilization of antimicrobial agents to food packaging materials.
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.
Effect of 0, 6, 10, 20, 40 mg/ml of SMPS on E. coli 0157:H7 growth in TBS at 25°C. ( ) PS control
0
2
4
6
8
10
12
0 5 10 15 20
Time (h)
Log 1
0 CFU
/ml
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
Polyamine
Cleaning Cycle
Use Cycle
Cl2Cl2
Cl2Cl2
Cl2 Cl2Cl2Cl2
Re-charging films for antimicrobial activity
Antimicrobial activity of control and modified films against E. coli K12, P. fluorescens, L. monocytogenes, and B. cereus.
Rechargeability of PE-polyCOOH-Cl: Antimicrobial activity of PE-polyCOOH-Cl against E. coli K12 after successive uses,
washes, and re-chlorination.
Indicating Films:Polymer surface-bound immunochemistry
to isolate and detect and photographic process to amplify signal
• Cheap• Simple• Rapid• Sensitive • Specific (immunochemistry)• Large amplification (10*9) • False negatives low
Conclusions• Bioactive materials can be covalently
attached to polymers making the surface bio-active.
• Nano technology can modify surface properties in ways which could be useful.
• Cost will be a major impediment to commercialization.
• Processing in situ may replace some selected conventional processes.
• Investment in research is needed.