Bio-plastics and Edible Films for Food Packaging

Mohammed Sabbah 1*, Asmaa Al-Asmar2, Nesreen Mansor, Dana Yaseen

1 Department of Nutrition and Food Technology, An-Najah National University, Nablus, Palestine 2 Analysis, Poison Control and Calibration Center (APCC), An-Najah National University, Nablus, Palestine

* Corresponding author: m.sabbah@najah.edu

Challenges of Environment in the Arab Region Conference

Plastic revolution

Plastic bottles were first used commercially in 1947 but remained relatively expensive until the early 1950s when high-density

polyethylene was introduced.

Plastics production (tonnes x 10⁶)

Global plastics production

60,000 plastic bags, used every five seconds

2,000,000 plastic bottles, used every 5 minutes

Disadvantages of plastic

Anti-pollution strategy

Bioplastics

- bio-based, biodegradable… or both

- similar properties of conventional plastics

- additional advantages (reduced carbon footprint,

additional waste management options, composting).

1- Bio-based monomers obtained by fermentation or conventionalchemistry (e.g. lactic acid) and polymerized in a second step topolylactic acid (PLA).

2- Biopolymers synthesized directly in microorganisms or ingenetically modified crops (e.g. polyhydroxyalkanoate, PHA)

3- Natural biopolymers (e.g. polysaccharides and/or proteins)recovered from organic wastes.

Bioplastics of different origin

Bioplastics production (tonnes x 10⁶)

Global production capacities of bioplastics

Bioplastics application

Mulchingsheets

Edible films: coating and wrapping

Bio-plastics from Starch-based polymers Mater-Bi®

• Maize and/or potatoe starch in blend withpolycaprolactones and other biodegradable esters

• Europeas most common bioplastic

Source: www.novamont.com

Advantages Disadvantages

Polysaccharide-based

❑ Structural stability and goodmechanical properties.

❑ Poor water vapor and gasbarrier properties.

Protein-based ❑ Good mechanical, optical, andgas barrier properties.

❑ High sensitivity tomoisture and poor watervapor barrier properties.

Hydrocolloid materials

Nigella sativa defatted seed cake (NsDSC)

❑ Seed high nutritional value❑ Seed high yield

❑ UP to 50% proteins in the DSC❑ High protein solubility

Nigella sativa (Ns) seeds

Ns oil

Defatted

cake of Ns

Acid/base protein

extraction

❖Chitosan is a linear cationic polysaccharidederived from chitin,

❖is water-soluble, non-toxic, biocompatible, andexhibits antibacterial, antifungal and antitumoractivities,

❖adheres to negatively charged surfaces,

❖is widely used in food, agriculture, medicine,pharmaceutics and cosmetics.

More than 100 billion tons of chitin are annually produced

(Muxika et al., 2017)

Chitosan

Ref: Ciriminna et al., 2015, Biofuels, Bioprod. Bioref.

Pectin preparation

Film preparation

Film preparation procedure

NsDSCFilm

Zetasizer nano ZSP

TotalPerm apparatus

permeability meter

Instron universal testing

instrument model no. 5543A

FFS and film characterization

Scanning electron

microscope (SEM)

Bruker model ALPHA

FTIR-ATR spectrometer

Sealing machine with vacuum

Micrometer

2. Nanoparticles 1. Plasticizing

Improvements of bioplastics and edible films features

Improvement

3. Cross-linker

1. Plasticizers

SorbitolGlycerol (GLY)

Generally small and non-volatile organic additives used to:✓ increase film flexibility✓ reduce material cristallinity and brittleness✓ reduce intermolecular forces✓ increase free volume and polymer chain movements

Most used plasticizers

Polyamines

Spermine (SPM)

Spermidine (SPD)Putrescine

Development of chitosan (CH)-based films plasticized with SPD ± GLY

Ref: Sabbah et al., (2019) Food Hydrocolloids 96 (2019) 29–35

Film Thickness(µm)

TS (MPa)

EB(%)

YM(MPa)

Viscofan NDX 30.0 ± 3.0 36.6 ± 8.1b 13.1 ± 2.9 356.2 ± 29.1b

CH 0.6% 31.5 ± 4.2 52.2 ± 4.2a 10.1 ± 2.5 3438.1 ± 506.3a

+ 5 mM SPD 49.8 ± 4.2a,b 30.3 ± 4.5b 30.4 ± 3.5a,b 965.4 ± 36.6a

+25 mM GLY 80.7 ± 3.1a,b 12.5 ± 2.3a,b 82.5 ± 2.0a,b 130.5 ± 5.2a,b

+ 5 mM SPD + 25 mM GLY 82.0 ± 2.5a,b 8.5 ± 2.5a,b 118.7 ± 5.2a,b 24.4 ± 2.2a,b

Effect of SPD ± GLY on CH film mechanical properties

*Significantly different values compared to those observed analyzing Viscofan NDX (a) and to

those observed analyzing CH film obtained in the absence of plasticizers (b).

Ref: Sabbah et al., (2019) Food Hydrocolloids 96 (2019) 29–35

Grape Juice

NsDSCPowder

Grape Juice (GJ)

NsDSCFilm

1 2 4 6 8 10

20

Grape Juice (GJ) concentration (% v/w protein)

NsDSC with different GJ concentrations

Effect of GJ on film of NsDSC mechanical properties

2. Nanoparticles

Nanoparticles(NPs)

NPs

NsDSC

Protein concentratedCarbohydrate residue

Grinding

Dewaxing

Delignification

Bleaching

Hydrolysis

Ns-CNPs

NsDSC protein + Ns-CNPs film

Ns-CNPs

0

20

40

60

80

0 0.5 1 2 3

Ns-CNPs (%)

Thickness (µm)

0

5

10

15

20

25

0 0.5 1 2 3

Ns-CNPs (%)

TS (MPa)

0

5

10

15

20

25

30

0 0.5 1 2 3

Ns-CNPs (%)

EB (%)

0

150

300

450

0 0.5 1 2 3

Ns-CNPs (%)

YM (MPa)

Effect of differen concentration of Ns-CNPs on Ns-DSC films

Incubation at 37ºC for 2 h

mTGaseNsDSC

3. Crosslinking

Microbial transglutaminase

(mTGase) from

Streptoverticillium sp

Intra-molecular crosslink

H2N − CH2CH2CH2CH2

CH2CH2C − NH2

O

CH2CH2C N − CH2CH2CH2CH2

O

H

NH3

TG

+

H2N − CH2CH2CH2CH2

H2N − CH2CH2CH2CH2

CH2CH2C − NH2

O

CH2CH2C − NH2

OO

CH2CH2C N − CH2CH2CH2CH2

O

H

CH2CH2C N − CH2CH2CH2CH2

OO

HH

NH3

TGNH3

TGTG

+

CH2CH2C − NH2

O

NH2

CH2CH2CH2CH2

N

CH2CH2C

O

H

CH2CH2CH2CH2

NH3

TG

CH2CH2C − NH2

O

CH2CH2C − NH2

OO

NH2

CH2CH2CH2CH2 NH2

CH2CH2CH2CH2

N

CH2CH2C

O

H

CH2CH2CH2CH2

N

CH2CH2C

OO

H

CH2CH2CH2CH2

NH3

TGNH3

TGTG

Inter-molecular crosslink

Characteristics of microbial TG (EC, 2.3.2.13): • Active in a wide range of pH (4-9)

• Resistant between 4-60°C

• Commercially available

• Food grade

Characteristics of mTGase

NsDSC films obtained at different concentrations of GLY after incubation with or without TGase (20 U/g protein) at

pH 8.0

* ** *

60

80

100

120

140

160

10 20 30 50

Thic

knes

s (µ

m)

GLY (%)

- TGase + TGase

*

0

1

2

3

4

5

10 20 30 50

TS (

MPa

)

GLY (%)

*

0

10

20

30

10 20 30 50GLY (%)

*

50

100

150YM

(M

Pa)

*

*

0

40

80

120

160

200

240

10 20 30 50

EB (

%)

GLY (%)

Film thickness and mechanical properties of NsDSC films obtained in the presence and absence of TGase (20 U /g

protein) at pH 8

The antimicrobial activity on Staphylococcus aureus of Ns-DSC film with or without mTGase

Food Application

Heat sealability of BVPC and CH films

*Control materials

Film Seal strength (N/m)BVPC + 42 mM, GLY 33.35 ± 4.61

BVPC + 5 mM, SPD 57.44 ± 3.54

BVPC + 42 mM, GLY + 5 mM, SPD 43.61 ± 8.20

CH + 25 mM,GLY 196.42 ± 8.46

CH + 5 mM, SPD 65.06 ± 1.84

CH + 25 mM, GLY + 5 mM, SPD 82.80 ± 6.14

LDPE* 216.80 ± 4.52

HDPE* 205.52 ± 7.12

Mater-Bi* 201.46 ± 6.61

Different food products wrapped under vacuum by BVPC, CH or LDPE films

Sausage

Za’atar

Peanuts

Nabulsi cheese

➢ Fresh semi-hard dairy product with moisture contentranging from 45% to 55%

➢Stored in 15-20% brine solution.

Unwrapped and Film-wrapped Nabulsicheese under vacuum

Titratable acidity

(TA)pH

Unwrapped CH BVPC LDPE

Ref: Sabbah et al., (2019). Food Hydrocolloids 96. 29–35.

Effect of wrapping on cheese pH and TA at different storage times

salted Nabulsi cheese

unsalted Nabulsi cheese

salted Nabulsi cheese

unsalted Nabulsi cheese

Images of unwrapped and wrapped groups of strawberries during storage time (days)

Ref: Al-Asmar et al., (2020). Nanomaterials, 10, 52; doi:10.3390/nano10010052

Innovative bioplastics were produced:a) by using SPD and GJ as second plasticizer

b) by mTGase-crosslinking

- Improvements of the shelf-life of unsalted Nabulsi cheesewas obtained by its wrapping with GLY-plasticized BVPC-and CH-based bioplastics.

- Extended the shelf life ofstrawberry up to 8 day byusing PEC with MSN film

Conclusions

FUTUREPAST

Bioplastics/edible films

Petroleum-basedPlastics