Today there is an ever-increasing interest in recovering flooded archival materials. Freeze-drying stands out as a valuable method as the water is frozen and the ice is then removed through sublimation. The present work is focused on the effect of freeze-drying on flooded paper contaminated with biodeteriogenic microorganisms (i.e. a bacterium Staphylococcus epidermidis, a yeast Rhodotorula mucilaginosa and a filamentous fungus Alternaria alternata). The effect of freezing and drying on microorganism survival and growth has been separately evaluated. In particular, different operative conditions for freezing (in a domestic freezer at about -20°C, at -40°C with a freezing rate of -1°C/min) and drying (200 μbar at 0°C and 20°C) have been tested. All the tested strains were able to survive after freezing and drying phases, nevertheless a different behaviour was observed: the growth of S. epidermidis was the same as that of the control, R. mucilaginosa showed a slight growth and carotenoid production increase, while A. alternata was inhibited, in particular after the freezing at -40°C, followed by a low temperature drying rate step.
On the effect of freeze-drying on paper-borne microorganisms / Fissore, D.; Lucchese, M.; Mollea, C.; Barresi, A. A.; Bosco, F.. - ELETTRONICO. - (2019), pp. 303-309. (Intervento presentato al convegno 7th European Drying Conference tenutosi a Torino, Italy nel 10-12 July 2019).
On the effect of freeze-drying on paper-borne microorganisms
Fissore D.;Mollea C.;Barresi A. A.;Bosco F.
2019
Abstract
Today there is an ever-increasing interest in recovering flooded archival materials. Freeze-drying stands out as a valuable method as the water is frozen and the ice is then removed through sublimation. The present work is focused on the effect of freeze-drying on flooded paper contaminated with biodeteriogenic microorganisms (i.e. a bacterium Staphylococcus epidermidis, a yeast Rhodotorula mucilaginosa and a filamentous fungus Alternaria alternata). The effect of freezing and drying on microorganism survival and growth has been separately evaluated. In particular, different operative conditions for freezing (in a domestic freezer at about -20°C, at -40°C with a freezing rate of -1°C/min) and drying (200 μbar at 0°C and 20°C) have been tested. All the tested strains were able to survive after freezing and drying phases, nevertheless a different behaviour was observed: the growth of S. epidermidis was the same as that of the control, R. mucilaginosa showed a slight growth and carotenoid production increase, while A. alternata was inhibited, in particular after the freezing at -40°C, followed by a low temperature drying rate step.File | Dimensione | Formato | |
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https://hdl.handle.net/11583/2739536