1. EDIBLE COATINGS AND FILMS TO
IMPROVE FOOD QUALITY
Ms. Latika Yadav (Research Scholar), Dept. of Foods
and Nutrition, College of H.Sc,Maharana Pratap
University of Agriculture and Technology, MPUAT,
Udaipur, rajasthan-313001, email.id:
a.lata27@gmail.com

2. OUTLINE
1. Introduction
2. History of edible films and coatings
3. Use of edible films and coatings
4. Components of edible coatings
5. Role of edible films and coatings
6. Commercial edible coating and films
7. Application of commercial coating
8. Method of coating application
9. Encapsulation of flavours , nutraceuticals
and antibacterials
10. Comparison of typical food coatings and
pharmaceutical coatings
11. Evaluation of edible films

3. INTRODUCTION
Any type of material used for enrobing (i.e.. coating or
wrapping) various food to extend shelf life of the product
that may be eaten together with food with or without
further removal is considered an edible film or coating.
Edible films provide replacement and/or fortification of
natural layers to prevent moisture losses, while
selectively allowing for controlled exchange of important
gases, such as oxygen, carbon dioxide, and ethylene,
which are involved in respiration processes.
A film or coating can also provide surface sterility and
prevent loss of other important components. Generally,
its thickness is less than 0.3 mm.

4. HISTORY OF EDIBLE FILMS
AND COATINGS
Edible coatings have been used for
centuries to protect foods and prevent
moisture loss.
The first recorded use was in china in the
12th century on citrus, and later in
England using lard or fats, called larding
to prolong shelf life of meat products.
Since the early to mid 20th century,
coatings have been used to prevent water
loss and add shine to fruits and
vegetables, as casings using collagen or
collagen-like material for sausages, and
as some sort of sugary coatings on
confectionaries, including chocolate.

5. Use of Edible Films and Coatings
1. Reduce water loss
2. Reduce gas diffusion
3. Reduce movement of oils and fats
4. Reduce movement of solutes
5. Reduce loss of volatile flavors & aromas
6. Improve structural properties (hold it
together)
7. Incorporate pigments, flavoring, & food
additives
8. Improve appearance (e.g., gloss)
9. Inhibit transfer of moisture and oxygen
10. Reduced mold growth
11. Reducing frying fat uptake
12. Reduce adhesion to cooking surface.

6. COMPONENTS OF EDIBLE COATINGS
Polymers are the main ingredients of many edible coatings. Many edible polymers
are nontoxic, simple derivatives of cellulose, one of the most abundant natural
polymers in nature, being a component of plant structure.
The coatings made from polymeric edible films are generally designed to be flexible
and tough.
Components
of edible
coating
polysaccharides proteins lipids resins composite

7. 1. POLYSACCHARIDES: coatings are hydrophilic and intermediate among coatings
materials in gas exchange properties but are poor barriers to moisture. These include
cellulose derivatives, starch derivatives, chitosan, pectin, carrageenans, alginates and
gums.
Polysaccharides
films/
coatings
Microbial
Seaweeds extract starch Chitin/chitosan cellulose
polysaccharides
levan carrageenan dextrins CMC
pullulan alginates amylose HPC
MC

8. 2. PROTEINS: are similar in properties, being also hydrophilic, and include corn
zein, wheat gluten, peanut, soy, collagen, gelatin, egg, whey and casein.
Protein films/ coatings
gelatin
zein
Wheat gluten
casein
Whey protein
Albumen + gelatin
Soy protein

9. 3. LIPIDS: lipds and waxes tend to be more permeable to gasses but present a
better barrier to water vapour and includes beeswax ,petroleum based waxes,
vegetable oils etc.
Lipid films
/coatings
surfuctants waxes
tweens lecithin beeswax carnauba paraffin

10. Properties of Hydrocolloids
Properties of Lipid Coatings
•Poor resistance to water vapor
•Barriers to oxygen & carbon dioxide •Barriers to water vapor
•Mechanical strength •Coatings add gloss
•Water soluble (i.e., hydrophilic) •Lack structural strength & durability
•Water insoluble (i.e., hydrophobic) •Require supporting matrix
•Many lipids exist in crystalline form
4. RESINS: resins are the least permeable to gases and intermediate in
resistance to water vapor and include shellac, wood rosin, and coumarone
indene resin.
female lac bug shellac Wood rosin coumarone indene

11. 5. Composite films: Blend of polysaccharides, proteins, lipids or resins.
Structure of Composites

12. Properties of Composites
•Combine advantages of components
•Lessen disadvantages of components
•Example
–Lipids provide a barrier to water vapor movement
–Hydrocolloids provide the supporting matrix
•Example
–Films of casein and acetylated monoglycerides are effective barriers to water loss in
fruits and vegetables
Film Additives
•Modify mechanical properties of the film
•Cause significant changes in barrier properties

13. Types of Film Additives
•Emulsifiers keep the components in solution.
Components of Film Additives
•Surfactants reduce the surface tension of the
•Antimicrobial compounds film formulation to achieve uniform coverage.
•Antioxidants Surfactants may be used to stabilize the
•Flavor and aroma compounds dispersed phase in a polymeric solution prior to
•Pigments applying it to food surface.
•Preservatives
•Vitamins •Plasticizers:
Plasticizers are used to modify mechanical
properties of films and coatings
Plasticizers, which are small molecules such as
glycerol, propylene glycol, or polyethylene
glycol are used to control viscosity of the liquid
formulation, add flexibility and tensile strength
and control surface tension.

14. ROLE OF EDIBLE FILMS AND COATINGS
1. Antimicrobial agents: incorporating antimicrobial compounds into edible films or
coatings provides a novel way to improve the food safety and shelf life of ready-to-eat
foods.
Common antimicrobial agents used in food systems, such as benzoic acid, sodium
benzoate, sorbic acid , pottassium sorbate, and propionic acid, may be incorporated into
edible films and coatings. Example:
•Starch based coating containing potassium sorbate were
applied on the surface of fresh strawberries for reducing
mcrobial growth and extending storage life.
•Chitosan coatings containing potassium sorbate were
shown to increase antifungal activity against the growth of
Cladosporium and Rhizopus on fresh strawberries.

15. 2. Antioxidants and antibrowning agents:
Antioxidants can be added into coating matrix to protect against oxidative rancidity,
degradation and discoloration of certain foods. E.g. nuts were coated with
pectinate, pectate, and zein coatings containing BHA, BHT, and citric acid to
prevent rancidity and maintain their texture.
Ascorbic acid was incorporated into edible coatings to reduce enzymatic browning
in sliced apples and potatoes.
3.Nutrients, flavours and colorants:
Edible films and coatings are excellent vehicles to enhance the nutritional value
of fruits and vegetables by delivering basic nutrients and nutraceuticals that are
lacking or are present on only low quantity.
Xanthan gum coating was utilized to carry a high concentration of calcium and
vitamin E, for not only preventing moisture loss and surface whitening, but also to
significantly increase the calcium and vitamin E contents of the carrots.

16. Classification of some antimicrobial, antioxidant agents and additives
allowed for used in food coatings
Food additive classification Allowed use
Benzoic acid Preservative GRAS
Clove bud oil Essential oil GRAS
Potassium sorbate Preservative GRAS/FS
Propionic acid Preservative GRAS/FS
Calcium chloride Antimicrobial agent GRAS/FS
Ascorbic acid Antioxidant, preservative, GRAS
colour stabilizer, nutrient
Butylated hydroxyanisole Antioxidant GRAS/FS
(BHA)
Butylated hydroxytoluene Antioxidant GRAS/ FS
(BHT)

17. Edible coatings have been successfully applied in processed foods such as meat,
cereals, confectionaries, dried fruits, nuts and fresh and fresh-cut fruits and
vegetables.
These coating improves the quality and shelf life of foods.
These films acts as a novel packaging systems and control the release of active
compounds such as antioxidants, flavours, and antimicrobial agents.
1. Meat films and coatings
2. Cereal coatings
3. Raisin and Nut coatings
4. Confectionary coatings
5. Strips and pouches

18. Some commercial edible coating and films
Commercial composition uses Web site
name
natureseal® Ascorbic acid, Browning www.natureseal.com
calcium chloride, inhibition,
hydroxypropyl maintain taste,
methylcellulose texture and colour
of fresh-cut fruits
and vegetables
Semperfresh TM Sucrose esters of Coating of whole www.paceint.com
short-chain pears and cherries
unsaturated fatty to control weight
acid and sodium loss and excess
salts of respiration, retain
carboxymethyl moisture, and
cellulose preserve natural
colour of fruit
Pro-long TM Sucrose Coating for fresh www.matrose.com
polyesters of fruits and
fatty acids and vegetables
sodium salts of
carboxy-methyl
cellulose

19. Mantrocel ® hydroxypropyl Film coating for tablets www.matrose.com
methylcellulose and capsules, binder,
filler, matrix, stablizer
crystalac ® Shellac Confectionary glaze www.matrose.com
Crystalac ® Zein Confectionary glaze www.matrose.com
Z2
Flavoured film Films made Breath freshners, oral www.watson-
strips from hygiene, sugar free inc.com
hydrocolloids, candy, caffeine/energy,
plasticizers, and vitamin/nutrient
active strips
compounds,
flavours and
colorants
Origami ® Fruit and Wrapping, pouches, www.origamifoods.c
wraps vegetable- based sachets om
films with
bilayer protein
films

20. APPLICATION OF COMMERCIAL COATING
EDIBLE COATINGS can be utilized for most foods to meet challenges associated
with stable quality, market safety, nutritional value, and economic production
cost. The potential benefits of using edible coatings on fresh and processed food
products are:
1. Coating can serve as a moisture barrier on the surface of fresh and minimally
processed produce for helping to alleviate the problem of moisture loss during
post harvest storage, which leads to weight loss and changes in texture, flavour
and appearance.
2. Coating also function as a gas barrier for controlling gas exchange between the
fresh produce and its surrounding atmosphere, and thereby decrease
respiration and delay deterioration, retard enzymatic oxidation, and protect
against from browning discoloration and loss of texture during storage.

21. 3. Coating protect produce from physical damage caused by mechanical impact,
pressure, vibrations and other factors.
4.Coating functions as a carriers of active ingredients, such as antimicrobials,
antioxidants, nutraceuticals, colors, flavours and other additives used to improve
quality.
Successful application of edible coatings on food is dominated by several factors:
• type of coating material
• Its specific formulation
• The method of application
• The surface characteristics of the food

22. METHOD OF COATING APPLICATION
Several coating application methods including:
1. Dipping
2. Dripping
3. Foaming
4. Fluidized-bed coating
5. Panning
6. Spraying
7. Electrostatic coating
The selection of an appropriate method depends on the characteristics of the food, the
coating materials, the intended effect of the coating, and the cost.

23. 1. Dipping: edible coatings can be applied by dipping products
in coating solutions and then allowing excess coating to drain as
it dries and solidifies.
Dipping has been commonly used for coating fruits, vegetables,
and meat products.
The first reported dipping application was by the Florida citrus
industry, where the fruits were submerged into a tank of emulsion
coating. Fruit was then generally conveyed to a drier under
ambient condition
2. Dripping: This coating application method is
the most economic. In addition, it has the ability to
deliver the coating either directly to the
commodity surface or to the brushes. However,
due to relatively large droplet sizes, good uniform
coverage can only be achieved when the
commodity has adequate tumbling action over
several brushes that are saturated with the
coatings.
Dripping has been commonly used for coating
fruits and vegetables

24. 3. FOAMING: foam application is used for some emulsion coatings. A foaming agent is
added to the coating or compressed air is blown into the applicator tank. Extensive
tumbling action is necessary to break the foam for uniform distribution. The aggitated foam
is applied to commodities moving by on rollers and cloth flaps or brushes the distribute the
emulsion over the surface of the commodity.
This type of emulsion contains little water and therefore dries quickly, but inadequate
coverage is often a problem.

25. 4. FLUIDIZED-BED COATING: is a technique that can be used to apply a very thin
layer onto dry particles of very low density or small size. It was originally developed as a
pharmaceutical coating techniques but is now increasingly being applied in the food
industry
It may be applied to enhance the effect of functional ingredients and additives such as
processing aids, preservatives, fortifiers,flavours and other additives for ease of handling,
improved asthetics, taste and colour.
Bakery products are commonly coated using fluidized-bed techniques.

26. 5. PANNING: panning is usually employed for coating candies ,nuts, and some
processed fruits that are characterized by a smooth, regular surface obtained by polishing
action in the pan. The technology involves a stainless steel pan that is enclosed and
perforated along the side panels. The coating is delivered by a pump to spray guns
mounted in various parts of the pan.
Panning is a slow process, in which the pan speeds vary based on the size of the centre.
For ex- large size nuts require speeds of 15rpm.

27. 6. SPRAYING: when a thin and uniform coating is required for certain surfaces,
spraying is useful. This the most popular method for coating whole fruits and
vegetables, especially with the development of high-pressure spray applicators and
air- atomizing systems. Spray applications are also suitable when applying films to a
particular side or when a dual application must be used for cross-linking, as is
practised with alginate coating.

28. 7. ELECTROSTATIC COATING: is a process that employs charged particles to
improve efficiently coat a surface. Powdered particle or atomized liquid is initially
projected towards a conductive surface using formal spraying methods and then
accelerated toward the surface by a powerful electrostatic charge.
The exact performance of liquid electrostatic coating systems for food applications is not
well known. These coating shown great promise in some applications, including the
impregnation of bread with edible vegetable oil and coating of confectionary and
chocolate products.
The success of an edible coating for meeting the specific needs of food
strongly depends on
•Its barrier property to gases, especially oxygen and water vapour
•Its adhesion to the surface
•Uniformity of coverage of coating and also
•Sensory quality of the coated food products

29. Encapsulation of flavours , nutraceuticals and antibacterials
Encapsulation is the technique by which one material or mixture of materials is coated
with or entrapped within another material or system. The coated material is called the
active or core material, and the coating material is called the shell, wall material, carrier,
matrix, or encapsulant.
Encapsulation technology is now well developed and accepted within the
pharmaceutical, chemical, cosmetic, food, and printing industries.
In food products, fats and oils, aroma compounds and oleoresins, vitamins, minerals,
colorants, and enzymes have been encapsulated, while in films of coating oils, aroma
compounds, antimicrobials, and enzymes have been encapsulated.

30. Encapsulation methods are broadly categorized as either
physical or chemical
Physical Methods
1. Extrusion
2. Fluidized bed
3. Pan coating
4. Atomization Chemical Methods
5. Spinning disk
6. Spray drying 1. Solvent loss
7. Spray chilling/congealing 2. Phase separation
3. Coacervation
4. Polymerization
5. Precipitation
6. Nanoencapsulation
7. Liposomes
8. Sol-gel

31. CAPSULES MATRICES: encapsulation of biomolecules can be achieved by
using two main methods:
1. The first consist in making capsules in which the compound included as a core
entrapped in a polymeric matrix.
2. The second method consists of developing films or coatings in which the
biomolecules are directly included and trapped just as a matrix but on a larger
scale.

32. Release Mechanisms
capsule formulations to achieve one or more release mechanisms to meet product
performance requirements.
Common Controlled Release Profiles
1. Triggered release – Release occurs due to a change in environment, such as pH,
temperature, moisture, pressure, electromagnetic. This is used to achieve immediate,
delayed or pulsatile release profiles.
2. Sustained release – Release occurs for an extended period of time. This can be used
to achieve constant active ingredient exposure for a fixed period.
3. Burst release
4. Combination release profiles
Release Mechanisms
1. Diffusion
2. Dissolution
3. Molecular trigger (such as pH)
4. Biodegradation
5. Thermal
Osmotic release is triggered by the absorption of
6. Mechanical
water into the microcapsule core. Subsequent
7. Osmotic swelling ruptures the microcapsule shell.

33. Encapsulation of nutraceuticals
•Several nutraceuticals molecules can be incarporated in
edible coatings such as vitamins, peptides, polyunsatturated
fatty acids, or antioxidants to increase the food nutritional
value.
•The main problem in incorporating nutraceuticals in food is
related to stability during storage . These reactive molecules
rapidly lose their activity due to oxidation or other chemical
reactions.
•Edible films and coatings used to protect these active
biomolecules from contact with foods. While incorporated in
coatings or encapsulated, there bioactive effect is preserved,
and nanoencapsulation increases the molecule’s
bioavailability.
•Milk proteins, maltodextrins and other modified starches are
largely used as encapsulation matrices .

34. Edible materials for nutraceuticals or antimicrobial molecule
encapsulation
The matrix used for nutraceuticals or antimicrobial molecules is of prime importance to
allow good preservation or controlled release of these active compounds
1. HPMC( hydroxypropyl methylcellulose):
• cellulose based materials are being widely used as they offer advantages like
edibility, biocompatability, barrier properties, and asthetic appearance as well as
being nontoxic, nonpolluting and having low cost.
• HPMC edible films are attractive for food applications because HPMC is a readily
available nonionic edible plant derivative shown to form transparent, odorless,
tasteless, oil-resistant, water- soluble films with very efficient oygen, CO2, aroma and
lipid barriers, but with moderate resistance to water vapour transport.
• The tensile strength of HPMC films is high, and flexibility is neither too high nor too
fragile, which make them suitable for edible coating purposes.

35. 2. PLA ( Polyacetic acid):
As a GRAS and biodegradable material, and also because of its biosorbability and
biocompatible properties in the human body, PLA and its copolymers
( especially polyglycolic acid) attracted the pharmaceutical and medical researchers.
PLA is a new corn-derived polymer and needs time to be an accepted and effective
active packaging material in the market.
PLA ( Polyacetic acid)

36. COMPARISON OF TYPICAL FOOD COATINGS AND
PHARMACEUTICAL COATINGS
Food coatings Pharmaceuticals coatings
Amount used Thickness of a fruit coating is Tablet film coatings are much thicker, often
2μm, and this makes up 0.02% of about 50 μm. Sugar coatings make up about
fruit weight 40% of pill weight.
complexity Typically one uniform layer Multiple layers are common
What is inside Usually food inside and air Before ingestion: active ingredient inside
and outside outside and air outside
the coating After ingestion: active ingredients inside
stomach and outside intestines.
Main Reduce gas ( oxygen or water Before ingestion: mask and impart color,
functions vapour) movement into or out of reduce gas movement into the active
the food ingredient.
After ingestion: mask and impart flavour,
reduce gas movement, control release rate of
active ingredient.

37. Food coatings Pharmaceuticals coatings
Important modeling Permeance of gas diffusion through Before ingestion: same as for food
parameters coatings, coating thickness, and gas coatings, plus diffusion of active
effusion through holes in the coating ingredients within the tablet.
After ingestion: diffusion of
active ingredient through wetted
coating, including leaking through
holes in the coating, possible
driven by osmotic flow.
Coating technology Processing to apply coatings must be Freedom to use extensive
cheap, gentle, and fast to avoid handling, higher temperatures,
product damage. Slow development more ingredients, and higher-cost
of new technology techniques have led to ever more
sophisticated and highly
engineered coatings.
Permitted GRAS food additives plus relatively Wide range of ingredients,
ingredients few other ingredients including many synthetic polymers

38. EVALUATION OF EDIBLE FILMS
1. BARRIER PROPERTIES
• Water vapour permeability (WVP): the rate of
water vapour transmission per unit area of flat
material of unit thickness induced and per unit
vapour pressure difference between two specific
surfaces, under specified temperature and
humidity conditions.
• Gas permeability :The permeability of oxygen
gas through a material is a critical factor
when it concerns the ability of a package to
prolong the lifetime of packaged food.
Gas permeability of two types:
• Oxygen permeability test
• Carbon-di-oxide permeability test

39. 2 . MECHANICAL PROPERTIES
1. Tensile strength (TS): The tensile strength of
a material quantifies how much stress the material
will endure before suffering permanent
deformation. This is very important in applications
that rely upon a polymer's physical strength or
durability.
2. Elongation (EL): The increase in a
sample's gauge length measured after a
rupture or break divided by the sample's
original gauge length is referred to as
elongation. The greater the elongation, the
higher the ductility or elasticity of the
material.

40. 3. Puncture test: This test method determines the
resistance of a stretch wrap film to the penetration of
a probe at a standard low rate, a single test velocity.
Performed at standard conditions, the test method
imparts a biaxial stress that is representative of the
type of stress encountered in many product end-use
applications. The maximum force, force at break,
penetration distance, and energy to break are
determined .
4. Texture analyzer: Texture analysis is
primarily concerned with measurement of the
mechanical properties of a product such as
hardness, softness, cohesiveness, guminess etc.

41. 3. American Society for Testing and Materials (ASTM) : ASTM International, formerly
known as the American Society for Testing and Materials (ASTM), is a globally
recognized leader in the development and delivery of international voluntary consensus
standards. Today, some 12,000 ASTM standards are used around the world to improve
product quality, enhance safety, facilitate market access and trade, and build consumer
confidence .

42. References
1. Elizabeth A. Baldwin.et.al; 2012,“ edible coatings and films to improve
food quality, second edition, CRC Press.
2. http://wenku.baidu.com
3. http://www.astm.org
4. http://www.foodsafetymagazine.com
5. http://www.inviz.com
6. http://www.wikipedia.com
7. http://www.google.com