Rate of drying and the survival of microorganisms

Abstract

The survival rate of cells of the genera Arthrobacter, Pseudomonas, Mycobacterium, Escherichia, Micrococcus and Saccharomyces when counted immediately after fast or slow drying (20 minutes and 24 hours, respectively) was rather similar. However, after prolonged periods of dry storage, the number of viable cells after slow drying was much higher as compared with the rapidly dried cells. Investigations with Escherichia coli demonstrated this phenomenon only when more than about 8 mg of water per 10(8) cells was available on a filter paper disc. In order to obtain optimum resistance to water loss the dessication period of 0.025 ml of suspension of E. coli must be longer than 13 hours.

Rates of Drying and Survival of Rhizobium meliloti Strains During Storage at Different Relative Humidities

“…Such a phenomenon could be prevented by a remoistening step, as demonstrated by the similar behavior of cells which were rapidly dried, remoistened, and slowly redried and cells which were only slowly dried. These results are in good agreement with the previous report of Antheunisse and Arkesteijn-Dijksman (2), who suggest that the cells are torn by rapid drying.…”

“…Cells that were dried in less than 3.4 h subsequently died during a 5-day storage period. Moreover, the lowest water content per specimen to which R. meliloti RCR2011 could be rapidly desiccated without causing serious damage was determined by comparison with the work of Antheunisse and Arkesteijn-Dijksman (2). These authors reported that harmful effects of rapid drying on survival during storage at 31% RH occurreci VOL.…”

“…The effect of drying rates on the survival of several genera of microorganisms during storage at 31% RH is well documented (2). However, the effects of the drying rate on the subsequent survival of Rhizobium meliloti strains during storage in different dried states have not been investigated.…”

Survival ofEscherichia coliO157:H7 andSalmonella typhimuriumin cow manure and cow manure slurry

“…The reason is probably that the dehydration rate was much faster in the thin layers of manure. It has been shown that a fast dehydration process results in increased microbial inactivation [12]. On the other hand, long term survival is improved by a low a w and maximum survival of dried cells is expected when the dehydration rate is slow and the ultimate water activity low.…”

A Mortality Model for Penicillium bilaiae Subjected to Convective Air Drying

“…In a state of dry anabiosis, metabolic processes within the living spore are slowed or halted, which extends shelf-life during storage at reduced moisture. A variety of factors (stresses) have been reported to infl uence viability loss of micro-organisms in the drying process including: temperature (Bigelow and Esty, 1920); drying rate (Antheunisse and Arkestelin-Dilksman, 1979); and fi nal cell moisture content (Josić, 1982). While kinetic and probabilistic models have been used for over 40 years in the food industry to predict microbial death during thermal and drying operations (McMeekin and Ross, 2002), those conditions are often severe whereas death rate predictions for drying microbial cells involves more mild processing environments.…”