WP 7 – R elease of components from coatings to fruit and nuts

1. 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

2. 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

3. Release of added polysaccharides 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

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

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

6. Cryosectioning

7. Release after 2h

8. Release after 6h

9. Release after 24h

12. 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.

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

15. Inhibitory effect of films on Saccharomyces cerevisiae growth

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

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

18. Effect on microbial growth of preservative in film - on fruit Film GDL: Kafirin (batch 4), 5% Glukono-δ-Lactone 15% Propylene Glycol, 30% 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 Microorganisms: Saccharomyces cerevisiae Botrytis cinerea

19. 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

20. GDL LA ”Sterile” pears

21. Direct after inoculation Yeast chamber Mould chamber

22. Mould - 7 days of storage No film LA GDL

23. Mould growth with LA coating 7 days 10 days 13 days

24. 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