Biopolymer Films and Potential Applications to Meat and Poultry Products Paul Dawson, James Acton, & Amod Ogale Clemson University Potential Advantages • Reduced dependence on petroleum sources • Use of U.S. agricultural raw materials • As a food contact layer to carry adjuncts • Biodegradability •Cost?? Definition of Biopolymer Packaging • Packaging produced from renewable, biological material Biopolymers for Packaging from biomass Polysaccharides Proteins Cellulose Casein Starch Whey Gums Gluten Chitosan/Chitin Soy Egg/meat synthesized Polylactate (PLA) Other polyesters microbial Polyhydroxy-alcanoates (PHA) – butyrate (PHB) Ref: Vibeke K Haugaard and Grete Bertelsen, Centre for Advanced Food Studies (LMC) The Royal Veterinary and Agricultural University, Copenhagen, Denmark Biopolymer films-commercial materials Material Supplier Trade name PLA Cargill Dow NatureWorks PLA Hycail Mitsui LACEA Starch Novamont Mater Bi Biotec Bioplast Earth Shell Earth Shell PHB Biomer Biomer Ref: Vibeke K Haugaard and Grete Bertelsen, Centre for Advanced Food Studies (LMC) The Royal Veterinary and Agricultural University, Copenhagen, Denmark Biodegradation •Microbial – Aerobic! compost or sludge – Anaerobic! methane + hydrogen • Animal feed • Chemical Optimal Packaging Requirements Product Shelf Barrier Needs life O2 CO2 H2O light MAP raw 1-2 " " " meat wk Raw meat 1-2 " wk Cooked 1-4 " " " meat wk Cured Meat 1-6 " " " " mo Biopolymer films-meat research • 1949 – Pearce & Lavers – carrageenan • 1952 – Klose et al – gelatin • 1963 – Allen et al – alginates • 1967 – Bauer et al – cellulose • 1971 – Mullen – wheat gluten • 1972 – Turbak – corn zein • 1972 – Turbak – soy protein • 1972 – Baker at al – albumen/soy/wheat protein • 1980’s and 1990’s – numerous (mostly cast films) Biopolymer films- applications • Moisture/oxygen barrier • Physical protection • Oil barrier • Breading adhesion • Texture modifier • Antimicrobial/Antioxidant carrier Coating vs. Film • Coating applied as a fluid • Coating adheres to the food surface • Coating is often consumed with the food Meat coating applications • Coatings reduce moisture loss in raw and cooked meat • Antioxidants added to coatings to preserve cooked meat flavor • Coatings used to reduce moisture loss/oxidation in frozen meat and fish Nisin-coated cellulosic films applied to frankfurters Research by Dr. Kay Cooksey, Clemson University Control 156 IU/mL 10,000 IU/mL 10 8 6 4 2 log CFU / Package / CFU log 0 0 102030405060 Day Biopolymer films- flexible films • Crosslinking required to form flexible film • Proteins and carbohydrates have the ability to crosslink and form a film matrix • Two principal methods of forming – Casting – Thermal compression • Extrusion methods Crosslinking Agents • Formaldeyde • Glutaraldehyde • Cysteine • Transglutaminase • UV radiation • Glyoxal Batch Processing - Compression BEFORE AFTER Biopolymer films- flexible films CAST COMPRESSED zein soy press laminated Continuous Processing Physical properties of films Film type Thickness Tensile Strength Elongation (mil) (MPa) (%) Heat-press soy protein 11.8 5.0 123 Cast wheat gluten 3.98 2.6 276 Cast whey protein/glycerol 4.33 13.9 31 Cast soy protein/glycerol NA 37 4.0 Cast corn zein 3.5 0.4 <1.9 cellophane 14.17 114 20 High density PE 0.98 17.3-34.6 300 Low density PE 0.98 8.6-17.3 500 0.75%chitosan/LDPE 4.48 9.2 60 CAST CORN ZEIN FILM 10 9 8 CONTROL 7 LAURIC ACID 6 5 NISIN 4 3 2 NISIN + LAURIC 1 ListeriaListeria monocytogenes monocytogenes (CFU/ml) (CFU/ml) 0 0 2 4 8 12 24 48 Time of Culture Exposure to Film (Hours) THERMALLY COMPACTED SOY PROTEIN FILM 10 9 CONTROL 8 NISIN 7 6 5 4 LAURIC ACID 3 2 NISIN + LAURIC 1 ListeriaListeria monocytogenes monocytogenes (CFU/ml)(CFU/ml) 0 0 2 4 8 12 24 48 Time of Exposure to Film (Hours) Protein Films Comparison of nisin diffusivity 3.0E-10 2.5E-10 a 2.3E-10 a /s) 2 2.1E-10 a 2.0E-10 1.8E-10 1.5E-10 1.0E-10 b Nisin Diffusivity (cm 5.5E-11 5.0E-11 0.0E+00 C-CZ C-WG HP-CZ HP-WG Film Type Application on bologna L. monocytogenes-inoculated turkey bologna exposed to biocide-impregnated soy films control nisin lauric acid N + L 7 control 6 lauric lauric + nisin cfu/ml 5 nisin 4 0171421 Days Turkey bologna inoculated with L. monocytogenes and packaged with nisin in wheat gluten film Non-nisin Nisin 4 a 3.5 a a,b a 3 a,b,c a,b,c a,b,c a,b,c a,b 2.5 a,b,c a,b,c a,b,c a,b,c 2 b,c 1.5 c,d Log Cfu/g 1 d 0.5 d d 0 0246810 -0.5 Time (weeks) CIE a-value Results for Steaks Allowed to Bloom Prior to Packaging with Antioxidant Films Film Control BHA BHT Rosemary Extract d-tocopherol 18 16 14 12 10 a-value 8 6 4 012345678910 Days Color Differences - Antioxidant Discs within Packaged Steaks BHT Control - no disk BHA Chitosan tested as a coating and film CH OH 2 CH2OH O O O OH OH R Cellulose: R= OH R Chitin : R=NHCOCH3 Chitosan : R=NH2 Chitosan coated onto drumsticks 12 11 a a,b a,b 10 b b 9 weight loss(%) 8 control 91% DE 91% DE + 93% DE 93%DE + P < 0.05 nisin nisin SEM = 0.7 n = 6 Chitosan coated onto drumsticks 4 a 3 b b c c 2 Log CFU/ml 1 control 91% DE 91% DE + 93% DE 93%DE + P < 0.05 nisin nisin SEM = 0.4 n = 6 8% chitosan within LDPE films - steak surface 10 9 8 7 6 0% chitosan 5 4% chitosan 4 8% chitosan delta a* value delta 3 2 1 0 0 1 2 3 4 5 6 7 8 days 8% chitosan within LDPE films - steak surface 7 6 5 4 0% chitosan 3 4% chitosan 2 total plate count plate total 8% chitosan 1 0 0246810 days Future • Coatings will still be developed for specific applications • Biopolymer films will eventually enter the market as cost and functionality get near that of synthetic polymers • Requirements for meat packaging make this one of the most difficult areas for biopolymers to meet.