Development of starch based barrier coating concepts against

Development of starch-based barrier coatings against
mineral oil for recycled paper
Dr. Doris Rengstl
EFPRO – CEPI 3rd Early Stage Researchers Workshop
25th November 2014
2
Problem of mineral oil components in recycled paper used
as food packaging
Announcement from European Food Safety Authority (EFSA), Federal Institute for Risk
Assessment (BfR) and Cantonal Laboratory of Zurich
 mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH)
from recycled paper are present in the food chain and are a potential human health hazard:
MOSH/MOAH migrate through gaseous phase or direct food contact into food
 no specific harmonised measures presently exist at EU level
 German draft law
limits by the BMEL Mineral Oil Regulation, third draft dated 24th July 2014
mineral oil content in board (used for all foods)
max. 24 mg/kg
MOSH C16-35
max. 6 mg/kg
MOAH C16-35
alternative
migration into food max. 2 mg/kg
max. 0.5 mg/kg
C20-C35 MOSH
C16-C35 MOAH
one possible solution to hinder MOSH/MOAH migration: BARRIER COATING
3
Permeation of volatile substances
board
barrier
coating food side
3
Transfer rate P according to
Dissolution-Diffusion Model
P=S•D
C1
p
1
C2
solubility
coefficient S
diffusion
coefficient D
2
•high polarity
(e.g. starch)
•high density
•high connectivity
•high crystallinity
p
Requirements for aqueous barrier coating:
• can be applied using standard coating equipment
• least possible change in barrier properties after creasing and folding processes
• no blocking, no invisible set-off
• no negative effects on the recyclability of paper and board
• suitable for food contact (recommendation XXXVI, FDA)
4
Starch – the most important reserve material in plant cells
Polysaccharide: chemical formula (C6H10O5)n; composed of α-D-glucose units
Amylose (helix): α (14) linked D-glucose
SUNLIGHT
CO2
STARCH
Amylopectin (branched): α (14) and
α (16) linked D-glucose
O2
WATER
5
Native starches and modified starches as barrier coating
Native starch: Variation in crop,
degree of degradation (α-amylase),
amylose/amylopectin ratio (%/%)
maize (27/73)
waxy maize (1/99)
wheat (28/72)
pea (68/32)
potato (21/79)
amylopectin starch (5/95)
Source: www.asv.nienborg.de
www.klopfermuehle.de
www.tomatengruen.at
www.menshealth.de
Modified starch: Variation in
degree of degradation and
modification
Modified starch
high degree of
degradation (hD)
low degree of
degradation (lD)
carboxylated potato starch, anionic
(cK)
hD
amylopectin-rich, carboxylated potato
starch, anionic (acK)
hD
hydroxypropylated, hot water soluble
potato starch ether (hhK)
hD
thermochemically degraded maize
starch (taM)
hD
cold water soluble, chemically
degraded potato starch ester (kcaK)
lD
lD
lD
lD
6
Determination of mineral oil migration with Tenax ®
Tenax ® (food simulant), 4g/dm2 (DIN 14388)
barrier coating
board
Tenax ® :
stainless steel
porous polymer material
chemical: poly(2,6-diphenylenoxide)
- very strong adsorber
- low affinity to water
- simulant for dry food
5 days/ 60°C
Stainless steel migration cell
Release of
adsorbed
components
Analysis
7
Native starch - determination of mineral oil migration with
Tenax®
Coating condition: 12 g/m2 on smooth board front side using a handsheet rod coater
high degree
of degradation
high degree
of degradation
low degree
of degradation
low degree
of degradation
Potato and pea starch show potential as a good barrier to the migration of mineral oil components.
8
Modified starch - determination of mineral oil migration
with Tenax®
Coating condition: 12 g/m2 on smooth carton board front side using a handsheet rod coater
Modified starch
carboxylated potato starch,
anionic, high degree of
degradation
cK (hD)
hydroxypropylated, hot water
soluble potato starch ether,
low degree of degradation
hhK (lD)
cold water soluble, chemically
degraded potato starch ester
kcaK
cK (hD), hhK (lD), kcaK show potential as a good barrier to the migration of mineral
oil components.
9
Plasticizer – increasing the flexibility of starch films
Starch forms optical defect-free coatings on board (SEM), but coatings are brittle and
mechanical processing needs to be improved!
 plasticizer: glycerin and polyvinyl alcohol (98% degree of hydrolysis; PVOH98)
Effective formulation (% related to dry starch):
•pkcaK: cold water soluble, chemically degraded potato starch ester (kcaK) with 10% PVOH
98 and 10% glycerin
•pcK (hD): carboxylated potato starch, (anionic; cK (hD)) with 10% PVOH 98 and 10% glycerin
•phhK(lD): hydroxypropylated, hot water soluble potato starch ether (hhK (lD)) with 10%
PVOH 98 and 10% glycerin
•pK: potato (0.005% amylase) with 10% PVOH 98 and 30% glycerin
optical, defect-free, flexible coatings (pinhole test, SEM)
10
Pigments - cost reduction of barrier coating
Using the following pigments:
•Standard kaolin (92 % by wgt. < 2 µm; 74 % by wgt. < 1 µm): approx. 275 €/t of dry pigment
•Standard calcium carbonate (GCC; 90 % by wgt. < 2 µm): approx. 120 €/t of dry pigment
Cost balance: Calculated for 1 tonne of barrier coating (costs for materials
only)
kcaK with 10% PVOH 98, 10% glycerin
75 % by wgt. kcaK with 10% PVOH 98,
10% glycerin and 25 % by wgt.
standard calcium carbonate
kcaK
1000 Euro
kcaK
749 Euro
PVOH 98
192 Euro
PVOH 98
144 Euro
glycerin
767 Euro
glycerin
574 Euro
total
1959 Euro
GCC
30 Euro
total
1497 Euro
In comparison: Cost of synthetic polymer coatings approx. 2000-4000 €/t
11
Starch-plasticizer-pigment - determination of mineral oil
migration with Tenax®
Coating condition: 12 g/m2 on smooth carton board front side using a handsheet rod coater
Mineral oil barrier effect is not influenced by introducing pigments into starch coating.
12
Reverse side coating - board and testliner
Coating condition: 20 g/m2 pre-coating + 20 g/m2 barrier formulation with handsheet rod coater
Pre-coating: 100 parts kaolin (aspect ratio 100) with 100 parts barrier formulation (used as binder)
Barrier formulation: pkcaK or 75 % by wgt. pkcaK + 25 % by wgt. GGC
Characterization
Testliner
Board
grammage in g/m²
160
400
mineral oil content MOSH/MOAH in µg/dm2
1812
1874
roughness according to Bendtsen in ml/min
1900 ±320.8 (reverse side)
1281 ± 150.6
surface tension in mN/m
44.87 (reverse side)
51.12
effective coating against mineral oil
component migration for testliner
and board
13
Food regulatory compliance
Acceptance
Limits by the BMEL Mineral Oil Regulation, third draft dated 24th July 2014
•Migration into food max. 2 mg/kg
max. 0.5 mg/kg
C20-C35 MOSH
C16-C35 MOAH
Calculation basis
Testliner: 20 g/m2 pre-coating + 20 g/m2 pkcaK
1 dm
• board / food = 6 dm2/kg (EU cube)
Tenax, MOSH C14-C35 43 µg/dm2, MOAH C14-C35 86 µg/dm2
→0.3 mg/kg MOSH C14-C35 ok ; 0.5 mg/kg MOAH C14-C35 ok
https://static.allyouneed.com/productpictures/05/large/14046/2028/1/Lam
bertz-Coco-Fleur-Kekse-125-g.jpg
1 dm
14
Summary
•
potato starch (0.005% amylase); hydroxypropylated, hot water soluble potato starch ether
(hhK (lD)); carboxylated potato starch, anionic (cK (hD)) and cold water soluble,
chemically degraded potato starch ester (kcaK) form a good barrier coating on board and
testliner to the migration of mineral oil components
•
PVOH 98 in combination with glycerin increase the flexibility of the starch coating
•
pigments such as standard kaolin and standard calcium carbonate reduce coating costs
without lowering the efficiency of the barrier effect of the starch coating
•
a starch-plasticizer formulation is a more effective binder for the pre-coating than a
synthetic binder
•
the coated testliner and board are recyclable
•
all coatings form defect-free films on testliner and board without blocking
15
Contact
Food packaging
Dr. Doris Rengstl
Phone: 089/12146-459
[email protected]
PTS
Hess Str. 134
80797 Munich
http://www.ptspaper.de
This research was conducted within
the framework of IGF project 17676N
16
Thank you for your kind attention!!!

Download Report