Chapter 12 Edible films coatings

Puncture Strength & Deformation
Properties of Some Edible Films
Materials
Carbohydrate
Water barrier Moderate Poor Moderate Poor Good Moderate
Oxygen barrier Moderate Moderate Good Good Poor Good
Encapsulation or carriage
Edible Films Added Different Pigments
Edible Films with Nutraceuticles
12.3 Requirements for Materials
Good sensory qualities High barrier and mechanical efficiencies Enough biochemical, physico-chemical and microbial stability Free of toxics and safe for health (GRAS) Simple technology Nonpolluting Low cost of raw materials and process
Chapter 12 Edible Films/Coatings
Films vs. Coatings
Film
– Films are normally regarded as stand-alone, standbeing formed separated of any eventual intended use – used as testing structures for determination of barrier, mechanical, solubility, and other properties of a film material
Casein Film
Whey Protein Isolate (WPI) film
Lipid
Paraffin
Waxes
Carnauba Beeswax
Lipid films/ coatings
Lecithin
Surfactants
Tweens
Acetoglycerides
Resin
Group of acidic substances Produced and secreted by plant cells
12.2 Mechanisms of edible coatings to preserve foods
Selective permeability properties Structural integrity & sensory properties Encapsulation or carriage
Tensile strength (TS)
– ASTM D882
Elongation (EL)
– ASTM D882
Puncture & deformation
– ASTM D 6241
Texture analyzer is used
Texture analyzer
Tensile Strength (TS) & Elongation (EL)
Coating
– Coatings involve formation of films directly on the surface of the object they are intended to protect
Outline
12.1 Development of edible coatings 12.2 Mechanisms of edible coatings to preserve foods 12.3 Materials for edible films/coatings 12.4 Applications 12.5 Evaluation of edible film 12.6 Legal aspects
Mechanical properties Moderate Moderate Moderate Moderate Poor NA
MC High amylose starch Gluten WPI Beeswax
Composite
Protein
Lipid
WPI+beeswax
Poor = 10-100, Moderate = 0.1-10 ,Good=0.01-0.1 g mm/m2dkPa

WVP
Definition
– The rate of water vapor transmission per unit area of flat material of unit thickness induced and per unit vapor pressure difference between two specific surfaces, under specified temperature and humidity conditions
Composite
– Often with lipids – Properties improved
Water barrier contrary to oxygen barrier
12.6 Legal Aspects
United States
– Allow coating with restrictions
Structural Integrity & Sensory Properties
Surface injury
Reduce Structural integrity & sensory properties Improve
Scarring Chafing Color Shininess Transparency
12.1 Development
12th and 13th centuries: WaxWaxcitrus (China) 15th century: Yuba--Asia Yuba--Asia 16th century: Fats—meat Fats— (England) 19th century :Sucrose -- nuts 1950s: Edible coating on meat Last 50 years
Purposes
Not meant to replace non-edible, nonsynthetic packaging materials Act as an adjunct
– Improve overall food quality – Extend shelf life – Possibly improve economic efficiency of packaging materials
Mechanisms
Selective Permeability Functions
Surrounding medium Coating or film Organic vapors
aromas
Water vapor Food
Gases
oxygen carbon dioxide nitrogen
Solute
Barrier properties
– Water vapor permeability – Gas permeability
Mechanical properties (ASTM) methods often used:
– American Society for Testing and Materials
12.4 Applications
Poultry, meat, fish and seafood Fruits, nuts, grains, and vegetables Confectioneries
Application Examples
Uncoated
Coated with chitosan
ASTM standard method E 96 – cup method
Gas Permeability
Oxygen permeability (OP)
– ASTM D 1434
Carbon dioxide permeability
– ASTM D 1434
Mechanical Properties
Types of Materials
Polysaccharide

Protein Types Lipid Resin Composite
Polysaccharide
Cellulose Chitin /chitosan Starch Seeweed extracts
Microbial polysaccharides Amylose Dextrins Alginates
– Trees and shrubs
Shellac is commonly used
Composite Films
Blend of polysaccharides, proteins, and/or lipids Utilize the distinct functional characteristics of each class of film-former film-
Strawberries after storage for 2 weeks
Application Examples (cont.)
Coated with chitosan Raspberries after storage for 3 weeks
Uncoated
12.5 Evaluations of Edible Films
Improvement of Sensory Properties
Encapsulation or Carriage
Flavors & spices Antimicrobial & antioxidant agents Pigments & light absorbers Other food additives
Definition of Edible Films
A thin layer of edible material formed on a food by casting, dipping, spraying, or brushing, as a coating or food component. They offer foods a selective barrier against the transmission of gases, water vapor, and solutes while also provide mechanical protection. Packaging/component
lipids salts additives pigments
Selective Permeability
Retards moisture migration Selective permeability Retards gas transport Retards solute transport Retains volatile vapors
Properties VS. Materials
Carbohydrate
– Water barrier: poor- moderate poor-
Protein
– Oxygen barrier: good
Lipid
– Water barrier: good – Mechanical properties: poor
Carrageenan
MC MC + HPMC HPC CMC
Polysaccharide Films/coatings
Pullulan Levan
Chitosan Film
Chitosan Coating
Protein
Gelatin Zein Wheat gluten Protein films/coatings Casein Whey protein Albumen+ gelatin Soy protein