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Final meeting, Cape Town, November 23-25, 2004
WP 7 Release of components from coatings to
fruit and nuts Katarina Nilsson, Mats
Stading, Susanna Edrud, Maria Petersson
Structure and Material Design The Swedish
Institute for Food and Biotechnology
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Final results

• Effect of different Aw in model gel food on
  release from film
• Effect of different Mw on substances in film on
  release from film

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Release of added polysaccharides

• Film Kafirin with plasticizer
• Polysaccharides fructose, maltose,
• raffinose, stachyose
• (quantified by HPLC)
• Model food Gels of gelatine,
• Aw0.95 and Aw0.85
• Exposure time 2, 6 and 24h

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Cryosectioning
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Release after 2h
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Release after 6h
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Release after 24h
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Conclusions

• Aw 0.95 induce faster release of polysaccharides,
  independently of Mw, than Aw 0.85
• The polysaccharides are accumulated in the
  surface of the Aw 0.85 model food while the
  polysaccharides are distributed through out the
  Aw 0.95 model food
• No clear relation between Mw and the release and
  migration of the polysaccharides, independently
  of Aw in model food, could be seen.

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Effect on microbial growth of preservative in
film model food
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Inhibitory effect of films on Saccharomyces
cerevisiae growth
Inhibition expressed as difference in log CFU/ml Kafirin Kafirin NPS NPS Acetem Acetem
4 days 1 month 4 days 1 month 4 days 1 month
Only film 0.07 0.14 0.58 0.44 0.1 0.09
Film with LA 1.06 0.97 6.62 6.62 6.736 6.743
Film with Ca-prop 1.436 0.153 6.736 0.783 3.68 0.16
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Botrytis cinerea after 18 days
Kafirin film
Kafirin film LA
Kafirin film LA Ca-prop
No film
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Penicillium expansum after 18 days
KafirinLA
Kafirin
KafirinLACa-prop
No film
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Effect on microbial growth of preservative in
film - on fruit
Film LA Kafirin (batch 4), 11 Glycerol,
13.3 Lactic Acid, 13.3 Poly Ethylene Glycol
400, 13.3
Film GDL Kafirin (batch 4), 5 Glukono-d-Lactone
15 Propylene Glycol, 30

Fruit Pear (Packham) Reference without
coating
Microorganisms Saccharomyces cerevisiae
Botrytis cinerea
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• Pears kept at 4C until 4h before inoculation
• Sterilized with spray of ethanol 70
• Inoculation both by needle under peel and swab on
  top of peel.
• Both film solutions were coated by spraying
• Stored in climate boxes, 85 RH and 20C for 16
  days

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GDL
LA
Sterile pears
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Direct after inoculation
Yeast chamber
Mould chamber
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Mould - 7 days of storage
No film LA GDL
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Mould growth with LA coating
7 days 10 days 13 days
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Summary and main conclusions of WP7

• There is a release of plasticizers and added
  preservatives from the film coating to model food
  and fruit
• The release and migration is dependent on Aw
  higher Aw result in faster kinetics
• An inhibitory effect on the growth of
  microorganisms can be achieved, both in a model
  system and on fruit, with preservatives added to
  the coating

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