Lecture 2 Antimicrobial coatings.pptpttzow.up.poznan.pl/files/prezentacje/20170508... · Microsoft PowerPoint - Lecture 2_Antimicrobial coatings.ppt [Compatibility Mode] Author: mhenriques

2017/05/14

1

LECTURE 2.

WHEY PROTEIN EDIBLE COATINGS WITH ANTIMICROBIAL ACTIVITY IN RIPENED CHEESE

Marta Henriques

2017

ESAC – IPC

College of Agriculture – Polytechnic Institute of Coimbra

Department of Food Science and Technology

Poznan University – PolandFaculty of Food Science and TechnologyErasmus mission

Part D. nonconventional applications

WPC films active coatings

2017/05/14

2

Films & Coatings

• Food Safety• Ensure microbiological safety and food protection from the

influence of external factors

• Edible coatings• Natural

• Biodegradable

• May incorporate active ingredients and additives

• May present similar properties to the synthetic coatings

Whey protein coatings applications

• Proved Characteristics…• Small water retention capacity (hidrophyllic)

• High oil and oxygen barrier capacity (similar to some synthetic polymers)

• Improve food characteristics with the incorporation of antioxidants and antimicrobials.

Applications

Fruits

Fresh/processed meat

Cheese

2017/05/14

3

Motivation

• Replacement of conventional/synthetic coatings (PVA) by naturalcoatings with antimicrobial activity

• Whey protein valorization (WPC) from dairy industry by-products

• Use of natural bioactive compounds as antimicrobials

• Evaluate how whey protein polymerization method influences the performance of cheese coatings

• Assess the effectiveness of antimicrobial whey protein edible coatings on cheese

uncoated

commercial coatingUV

modification (UV)

heat denaturation

(HD)(HD+UV)

WPC, glycerol, guar gum, tween 20, sunflower oil, lactic acid, natamycin

(Ramos, 2011)

physicochemical, microbiological and sensorial properties

ripened cheese

antimicrobial WPC coatings

natamycin

Part D. WPC-based coatings with antimicrobial activity

2017/05/14

4

Commercial HDHeat denaturation

UVUV polymerization

HD+UV

PVAPolyvinyl alcohol

Coating types

WPCwhey protein concentrate: 10% (w prot/w coat)

Glycerol (plasticizer): 50% (w gly/w prot)Guar gum (thickener): 0.7% (w thick/w coat)

Sun flower oil (hydrophobic compound): 10% (w oil/w coat)

Tween 20 (surfactant): 0.2% (w surf/w coat)

AntimicrobialNatamycin

2.5 g/L

AntimicrobialsLactic acid: 6 g/L

Natamycin: 0.125 g/L

PhotoinitiatorIrgacure 2969: 3.5% w phot/w prot

Positive control

Negative control

Uncoated cheese

Coating application

Commercial HDHeat denaturation

UVUV polymerization

HD+UV

Polymerization methods

Dry Dry DryDry

Heat treatment

Coating application

UV treatment

Heat treatment

Coating application

Coating application

UV treatment

2017/05/14

5

Coating performance on cheeseCheese properties

Physicochemical

Weight loss

MoistureFat

Protein

Sodium

aw

pH

Total Acidity

Texture

Hardness

Microbiological

Staphylococcusspp.

Pseudomonasspp.

Enterobactereacea

Yeasts & molds

Sensorial

Visual Appearance

Colour

Exterior:

whole cheese

Interior:

sliced cheese

Cheese - physicochemical properties

Weight loss

time (days)

0 5 10 15 20 25 30 35 40 45

Wei

ght

loss

(%

)

0

20

40

60

80

100

Uncoated HD UV HD+UV Commercial

Uncoated57% weight loss

Coated46-52% weight loss

- small cheese size- large ripening period

The coating type and polymerization method influence the weight loss profile

Part D. WPC-based coatings with antimicrobial activity

2017/05/14

6

Cheese - physicochemical properties

Moisture content

time (days)

0 5 10 15 20 25 30 35 40 45

Moi

stur

e (%

)

10

20

30

40

50

60

70

Uncoated HD UV HD+UV Commercial

Uncoated43% water loss

Coated33-39% water loss

UV and HD+UV coatings are more effective then commercial coating

Part D. WPC-based coatings with antimicrobial activity

time (days)

0 5 10 15 20 25 30 35 40 45

Ha

rdn

ess

(g)

0

2000

4000

6000

8000Uncoated HD UV HD+UV Commercial

nd> 6000 g

HD and Uncoated cheese have the lower hardness profiles

HD+UV and Commercialcoatings have the higher hardness profiles

Higher hardness

Higher effectiveness preventing water loss

Cheese - texture propertiesHardness

Part D. WPC-based coatings with antimicrobial activity

2017/05/14

7

Physicochemical properties

time (days)

0 5 10 15 20 25 30 35 40 45

Fa

t (%

)

10

20

30

40

50

Uncoated HD UV HD+UV Commercial

time (days)

1 15 30 45

Pro

tein

(%

)5

10

15

20

25

30

35

Uncoated HD UV HD+UV Commercial

aa

a

a a

b b bc

cc

Fat content Protein content

Part D. WPC-based coatings with antimicrobial activity

cheese - microbiological profile

Pseudomonas spp.

Enterobacteriaceae

time (days)

0 5 10 15 20 25 30 35 40 45

Log

(cf

u g

-1)

3

4

5

6

7

8

9

10

11

12

Uncoated HD UV HD+UV Commercial

Yeasts & Molds

time (days)

0 5 10 15 20 25 30 35 40 45

Staphylococcus spp.

Log

(cf

u g

-1)

3

4

5

6

7

8

9

10

11

12

Uncoated cheese- microbiological

development

Coated cheeses- microbiological

control or inhibition

Commercial is the most effective against yeasts and molds

HD+UV have the overall best microbiological performance

2017/05/14

8

Uncoated HD UV HD+UV Commercial

t0

t15

t30

t45

visual identification of molds after 30 days

No visual differences were identified between HD+UV and Commercialcoated cheeses

Part D. WPC-based coatings with antimicrobial activity

cheese - sensorial profile

Interior: sliced cheeseExterior: whole cheese

0

1

2

3

4

5shape

rind color

colour homogeneity

hardness

Uncoated

HD

UV

HD+UV

Commercial

1

2

3

4rind color

odor

consistency

general acceptability

flavor

holes

No significant differences (p<0.05) were obtained between treated cheesesThe HD+UV and the commercial are the most accepted cheeses.

2017/05/14

9

Conclusions in more detail…

• It was possible to produce natural whey protein edible films with antimicrobial activity

• The protein polymerization method influences the coating performance on cheese• Using only heat denaturation did not improve significantly the coating

efficiency• UV polymerization improved the coating efficiency

• Antimicrobial Whey Protein HD+UV coating• prevents more efficiently water loss• leads to physicochemical cheese composition similar to the commercial

coating• prevents and inhibits microbial growth• brings a good visual appearance to cheese

• Antimicrobial whey protein-based edible film produced by HD+UV polymerization is an effective alternative to commercial coatings

team

Carlos Pereira David Gomes

2017/05/14

10

Currently...

Mucor

Tempo (dias)

0 1 2 3 4 5

Diâ

metr

o (c

m)

0

2

4

6

8

10

CN EE CP

Penicillium

Tempo (dias)

0 1 2 3 4 5 6 7

Diâ

met

ro (

cm)

0

1

2

3

4

5

CN EE CP

Negative control

Positive control

Thymusmastichina

extract

TANKS FOR YOUR ATTENTION

Marta Henriques [email protected]