Novel approach in edible coating to increase the efficiency of barrier properties of coating.

1. 1
Presenting by
CHEDDE INDU
2017604108 M Tech (PFE)
APE 691 Credit seminar (0+1)
Layer by Layer edible coating on fruits and vegetables

2. Chairman Dr.K.THANGAVEL
Professor and Head,
Centre for Post-Harvest Technology,
TNAU, Coimbatore-3.
Member - I Dr.D. AMIRTHAM
Assistant Professor (Biochemistry),
Department of Food Process Engineering
Member - II Dr.T. PANDIARAJAN
Professor (FPE),
Department of Food Process Engineering
*Member - III Dr.Z. JOHN KENNEDY
Professor (Microbiology),
Centre for Post-Harvest Technology
2
Advisory committee

3. Introduction on edible coating
Raw materials used in edible coating
Layer by Layer technique
Types of interactions in LbL coating
Advantages and Disadvantages
Case study
References
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CONTENT

4. “Edible coatings are thin layers of edible material applied to the product
surface in addition to or as a replacement for natural protective waxy coatings
and to provide a barrier to moisture, oxygen, and solute movement for the
food”
(McHugh and Senesi, 2000)
Coating: A layer of substance spread over a
surface for protection or decoration
Edible: fit to be eaten (food)
especially by human
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INTRODUCTION

5. Edible coating
• Edible coatings are an environmentally friendly technology
that is applied on many products to control moisture transfer,
gas exchange or oxidation processes.
• It can provide an additional protective coating to produce and
can also give the same effect as MAP in modifying internal
gas composition.
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6. • Major advantage - several active ingredients can be
incorporated into the polymer matrix and consumed with the
food, thus enhancing safety or even nutritional and sensory
attributes.
• In contrast to conventional synthetic packaging material (i.e.,
plastic), the application of edible coatings reduces packaging
waste, is environmentally friendly and low-priced (Han and
Gennadios 2005).
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7. • Edible coatings must meet a number of special functional
requirements -- moisture barrier
solute or gas barrier,
water/lipid solubility,
color and appearance,
mechanical characteristics,
nontoxicity, etc.
• Coating on fruits and vegetables greatly depends upon the
temperature, alkalinity, thickness and type of coating, and the
variety and condition of fruit and vegetable (Park et al., 1994).
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Edible coatings on Fruits and
Vegetables

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Product
Adhesion
to surface
Barrier
property
Uniformity
Sensory
quality
Success of edible coating strongly
depends on :

9. Adhesion Property:
• In order to provide an effective protection, edible coatings
need to have good adhesion to the food surface (Falguera et
al., 2011).
• To receive good adhesion, the viscosity, density and surface
tension of the coating formulation should be adjusted to a
surface tension and roughness of a specific food product
(Lin & Zhao, 2007).
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10. 10
Source: Novel Food Preservation and Microbial Assessment Techniques by G.
Manios and N. Skandamis
Raw materials

11. Raw material Advantages Disadvantages Reference
Chitosan  Antimicrobial and
Antifungal activity
 Good mechanical
properties
 Low oxygen and
Co₂ permeability
 High water
sensitivity
 Peelman et al.,
2013
Gluten  Good oxygen barrier
 Good film foaming
properties
 Low cost
 High sensitivity to
moisture
 Brittle
 Peelman et al.,
2013
Whey protein  Good oxygen barrier
 Desirable film
foaming properties
 High water
vapour
permeability
 Kadham et al.,
2013
Soy protein  Barrier properties
against oxygen
permeability
 High water
sensitivity
 Pol et al., 2002
 Cao et al.,2007
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12. • LbL approach is based on the alternate deposition of different
biopolymers and allows for a more effective control over the
physicochemical properties and activity of edible coatings.
• LBL self-assembly, also known as electrostatic self-assembly
• The ionic self assembly technique, introduced by Decher in
1991 (G. Decher et al.1991) provides an elegant way of
controlling the composition of the resulting assemblies.
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Layer by layer (LBL) technique

13. • Controlling the thickness of coating (1-100 nm)is the major
advantage of employing LbL deposition method (Weiss et al.,
2006)
• Carrier of antimicrobial and antioxidant agent in addition to
providing barrier properties against moisture and gases.
• This method can easily be adapted for automated fabrication,
and is applicable to any substrate shape.
• Polycation material – Chitosan
• Polyanion material – Cellulose, pectin,
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14. • Alternating deposition of oppositely charged polyelectrolytes
such that the charge oscillates between positive and negative
with each layer deposition.
• While electrostatic attraction between the oppositely charged
polyelectrolytes is generally thought to drive the depositions.
• The amount of adsorbed chains dependent on
ionic strength
pH
charge densities
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Basic mechanism of LbL assembly

15. • LBL deposition methods do not only work with oppositely
charged polyelectrolytes but also with all kind of multi topic
molecules presenting mutually interacting binding sites.
LbL coating interaction types:
1) Electrostatic interaction
2) Hydrophobic interaction – Hydrogen bonding
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Chemical principle

16. • Electrostatic interactions are the most common chemical forces used
to prepare LbL structures.
• The original LbL method involved alternating sequential deposition
of polyelectrolytes, polycations and polyanions on a charged surface
(Decher et al., 1992).
• The LbL structures overall electroneutrality is gained by a charge
overcompensation mechanism, which is based on intrinsic and
extrinsic charge compensations and competitive ion pairing.
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1) Electrostatic Interaction

17. • Intrinsic charge compensation involves the pairing of certain
polyelectrolyte with oppositely charged polyelectrolytes.
• Eventually no counter-ions are present within the bulk of the
multilayer and all exchangeable charges are located at the surface.
• Extrinsic charge compensation is based on ion pairing with
charged counter-ions.
• Upon LbL assembly, this extrinsic charge compensation is converted
into intrinsic charge compensation, leading to the release of counter-
ions and solvating water molecules, additionally providing an
entropic driving force for the LbL assembly process.
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18.  Coating thickness polyelectrolytes concentration
 When an attraction between two polyelectrolytes is relatively
weak, the process is driven by both intrinsic and extrinsic
charge compensations.
 In this case, the LbL method will follow an exponential growth
mode - the amount of the adsorbed polyelectrolytes will
exponentially increase with the number of bilayers resulting in
materials with a micro scale thickness and a limited number of
bilayers (Joseph et al., 2014).
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19.  The hydrophobic effect represents the tendency of water to
exclude non-polar molecules. The effect originates from the
disruption of highly dynamic hydrogen bonds between
molecules of liquid water.
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2) Hydrophobic Interaction

20. • Hydrophobic interactions describe the relations between
water and hydrophobes (low water-soluble molecules).
• Hydrophobes are nonpolar molecules and usually have a long
chain of carbons that do not interact with water molecules.
• The mixing of fat and water is a good example of this particular
interaction.
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21. • Example: LbL coating by hydrophilic interaction
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22. 1. Dipping
2. Spraying
3. Brushing
4. Spin coating
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LbL assembly methods
Fruits and vegetables

23. 1) Dipping
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1. Dipping in 1st solution
having negative charges
2. Rinsing with water-to avoid
the loose interactions
3. Dipping in 2nd solution
having positive charges
4. Rinsing with water
• Slow deposition
• Layer thickness is more

24. • Fast deposition
• The substrate is never in contact with the stock liquid –
preventing cross contamination
• Suitable to atomization
• Applicable to large scale with large number of layers
• Improves the uniformity with thin layers
(M A Ford et al. 1999; Krogman et al. 2007)
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2) Spraying

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Fig: Application of LbL coating by spraying

26.  Most economic
 It has ability to deliver the coating either directly to the
commodity 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.
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3) Brushing

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Application of LbL coating on various F & V
Source: Arnon and Poverenov,. (2018) Review: Improving food products' quality and
storability by using Layer by Layer edible coatings.

28. Prolongs the
shelf life
Inhibits the
microbial
growth
Delivery of
active agent
Improves the
appearance
Enhances the
physiological
quality
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Advantages

29. LbL
coating
Lack of
Knowledge
and
machinery
Costly
Allergic
reactions
Food
safety
Issues
Sensory
implications
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Disadvantages

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Case study : 01
Objective:
The aim of finding polysaccharide-based edible coatings that convey: enhanced
quality, improved storage times, and an attractive appearance onto citrus fruits

32. • Sample : Mandarins
• Coating material: Cellulose and chitosan
• Coating method: Brushing
• Each treatment – 25 to 30 fruits
• 4 Experiments :
Ex: 01 – i. Chitosan(CH) 1.5%
ii. Methyl cellulose(MC) 1%
iii. Hydroxypropyl methylcellulose(HPMC) 1%
iv. Carboxymethyl cellulose(CMC) 1.5%
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Materials and methods

33. • Ex: 02 – four different CMC edible coating with glycerol at
0%, 2%,4% and 6%
• Ex:03 – 5 different coatings
i. CMC 1.5%
ii. CMC 1.5% with 0.3% steric acid
iii. CMC 1.5% with 0.6% steric acid
iv. CMC 1.5% with 0.3% oleic acid
v. CMC 1.5% with 0.6% oleic acid
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34. 34
• Ex: 04 - Treatments:
T1 – Carboxymethyl cellulose (CMC) 1.5%
T2 – Chitosan (CH) 1.5%
T3 – Polyethylene based commercial wax (PE-CW)
T4 – CMC 1.5% +CH1.5%
T5 – CMC 1.5% + CH 1.0%
T6 – CMC 1.5% + CH 0.5%
T7 – Control
• Storage period : 10days (20º C & Rh- 85%)
LbL coating

35. Fig: Schematic presentation of the electrostatic deposition method used to
form LbL edible coatings of mandarin fruits.
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36. Fruit firmness
Weight loss
Ethanol concentration
Internal gas composition
Sensory evaluation
Fruit gloss
Fruit ripening progression
Statistical analysis
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Analysis

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Results and discussion
Fig: Effect of LbL edible coatings with different concentrations of chitosan on
(A) firmness and weight loss and (B) ethanol andCO2 concentration

38. Fig: Effect of LbL edible coatings with different concentrations of chitosan
on (B) gloss and (C) progress of ripening of mandarin
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Best quality
Fig: Effect of LbL edible coatings with different concentrations of chitosan
on appearance

40. • The layer-by-layer coatings, based on a combination of two polysaccharides,
CMC and chitosan, showed the best performance and also best method to
alternative polyethylene-based waxes for mandarin fruit.
• CMC serves as an internal layer that provides good adherence to the
mandarins’ peel and chitosan serves as an external layer that improves the
coating’s properties.
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Conclusions

41. Objective:
 To develop and characterize the properties of a nanomultilayer coating.
 To evaluate LbL coating gas flow barrier properties affecting the shelf-life
of mango.
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Case study : 02

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Materials and methods
• Sample : Mangoes (Tommy Atkins)
• Coating material: Pectin 2.0% + Chitosan 1.0%
• Coating method: Dipping
• Immersion time – 15 min.
• Coating on PET – To study gases permeability
• Each treatment – 18 fruits
• Treatments:
T1 – Pec-Ch-Pec-Ch-Pec (5 layers LbL coating)
T2 – Control
• Storage period: 45 days (4º C & 93 % Rh)

43. Nano multilayer
• Uv absorbance
• Contact angle analysis
• SEM analysis
• Water vapor permeability
• Oxygen and Co₂
permeability
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Analysis
Mango quality
• Weight loss
• Total soluble solids
• Titratable acidity
• Statistical analyses

44. 44
Results and discussion
Fig: Effect of absorbance and contact angle on each layer of PET and mango

45. Fig: Scanning electron microscopy cross-section image of the nanolayered
coating (scale bar 500 nm) on PET
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46. Table: Effect of WVP, oxygen and Co₂ permeability on
PET and nanomultylayer PET
Parameter Method PET PET + 5 layers
Water vapor
permeability
(g m/Pa s m²)
Gravimetric
method
1.42 ± 0.39 ×10−11
0.019 ± 0.005 ×10−11
Oxygen
permeability
(g m/Pa s m²)
Gas
chromatograph
2.5 ± 0.03×10−14
0.069 ± 0.06×10−14
Co₂
permeability
(g m/Pa s m²)
Gas
chromatograph
39.7 ± 22.9×10−14 44.8 ± 32×10−14
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47. Fig: Effect of TSS, TA and mass loss on LbL Coated and Uncoated mangoes
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48. Fig: Mangoes on the 45th day of storage. (a) Uncoated mangoes; (b) coated
mangoes; (c) appearance of mangoes flesh exposed by a longitudinal cut of the
uncoated mangoes
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T1 – Control T2 – LbL coating
T1 – Control
T2 – LbL coating

49.  These findings suggest that the combination of the
antimicrobial and gas barrier properties of chitosan, with the
low oxygen permeability of pectin layers were possibly
efficient in the reduction of gas flow and on the extension of
the shelf-life of mangoes.
 Barrier properties were possibly improved by the nano-
structure of the coating.
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Conclusion

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Overall conclusion
Edible coating is alternative to MAP packaging which is
edible, biodegradable, eco friendly and less cost.
Layer by Layer coating is an one the best novel method to
improve the efficiency of barrier properties results in
increasing its shelf life than the single edible coating.
LbL works on the principle of self assembling electrostatic
interactions with in the polyelectrolyte.
Mechanization and lack of knowledge on the barrier
properties of coatings are the major drawbacks on this
method.

51.  Arnon, H., Granit, R., Porat, R., & Poverenov, E. (2015). Development of
polysaccharidesbased edible coatings for citrus fruits: A layer-by-
layer approach. Food Chemistry, 166, 465–472.
 Arnon, H., Zaitsev, Y., Porat, R., & Poverenov, E. (2014). Effects of
carboxymethyl cellulose and chitosan bilayer edible coating on
postharvest quality of citrus fruit. Postharvest Biology and
Technology, 87, 21–26.
 Bourtoom, T. (2008). Edible films and coatings: Characteristics and
properties. International Food Research Journal, 15, 237–248.
 Brasil, I. M., Gomes, C., Puerta-Gomez, A., Castell-Perez, M. E., &
Moreira, R. G. (2012). Polysaccharide-based multilayered
antimicrobial edible coating
 Jiang, B., & Li, B. (2009). Tunable drug loading and release from
polypeptide multilayer nanofilms. International Journal of
Nanomedicine, 4, 37–53.
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References

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