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-Biotechnology

• Molecular scale properties and applications of biological nanostructures.

“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

Effect of tether molecule on bioactivity

(f)(f)(d)(d)

(a)(a) (c)(b)

(e)

P P

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

Loss of naringin from grapefruit juice after exposure to CA film containing naringinase at 7°C

Controlled Release of MCP from Packaging Materials

CH2

HC = C – CH3

In situ Processing

• Removal of lactose in milk while stored by binding lactase to surface

Free Molecule Derivatized Molecule

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.

Immobilization on PS Beads

Spacer Molecule

Peptide

Polymer Bead

Antimicrobial peptide

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

Removal of Metals from Beverages

Chelating agent

Fe2+

Polyamine

Cleaning Cycle

Use Cycle

Cl2Cl2

Cl2Cl2

Cl2 Cl2Cl2Cl2

Re-charging films for antimicrobial activity

Structure and chlorination of PE-polyCOOH films.

Rechargeability of control and modified polyethylene films.

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.

Thank YouPRESENTED BY

Joseph H HotchkissProfessorCornell University

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