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 Final meeting, Cape Town, November 23-25, 2004

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

Film: Kafirin with plasticizer Polysaccharides: fructose, maltose, raffinose, stachyose (quantified by HPLC) Model food:Gels of gelatine, Aw=0.95 and Aw=0.85 Exposure time:2, 6 and 24h Release of added polysaccharides

Fructose (Mw 180) Maltose (Mw 342) Raffinose (Mw 504) Stachyose (Mw 666).

Microtome Gel cylinder 15 mm Ø 4 thin sections á 0,25  m gives 0.1 mm Dissolved and analysed by HPLC

Cryosectioning

Release after 2h

Release after 6h

Release after 24h

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.

Preservative: Lactic acid (13.3 % of protein cont.) Ca-propionate (5% of protein cont.) Microorganisms: Saccharomyces cerevisiae Penicillium expansum Botrytis cinerea Films: Kafirin Monoglyceride NPS Model Food: Agarose gel Aw 0.95, with glycerol and nutrients Effect on microbial growth of preservative in film – model food

Inhibitory effect of films on Saccharomyces cerevisiae growth Inhibition expressed as difference in log CFU/ml KafirinNPSAcetem 4 days1 month4 days1 month4 days1 month Only film: Film with LA: Film with Ca- prop:

Botrytis cinerea after 18 days No film Kafirin film Kafirin film + LA Kafirin film + LA+ Ca-prop

Penicillium expansum after 18 days No film Kafirin Kafirin+LA Kafirin+LA+Ca-prop

Effect on microbial growth of preservative in film - on fruit Microorganisms: Saccharomyces cerevisiae Botrytis cinerea Film LA: Kafirin(batch 4), 11% Glycerol, 13.3% Lactic Acid, 13.3% Poly Ethylene Glycol 400, 13.3% Fruit: Pear (Packham) Reference without coating Film GDL: Kafirin (batch 4), 5% Glukono-δ-Lactone 15% Propylene Glycol, 30%

Pears kept at +4°C 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 20°C for 16 days

”Sterile” pears GDL LA

Direct after inoculation Yeast chamberMould chamber

Mould - 7 days of storage No film LAGDL

Mould growth with LA coating 7 days 10 days 13 days

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