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Liquid formulation of the biocontrol agent Candida sake by modifying water activity or adding protectants
Author(s) -
Torres R.,
Usall J.,
Teixidó N.,
Abadias M.,
Viñas I.
Publication year - 2003
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2003.01843.x
Subject(s) - trehalose , glycerol , penicillium expansum , polyethylene glycol , water activity , food science , peg ratio , lactose , chemistry , yeast , biology , biochemistry , botany , postharvest , water content , geotechnical engineering , finance , engineering , economics
Aims: To evaluate the effect of modification of water activity ( a w ) and the addition of protective substances in the preservation medium of liquid formulations of the biocontrol agent Candida sake stored at 4 and 20°C. Methods and Results: The a w of the preservation medium of C. sake was modified from 0.72 to 0.95 by adding glycerol or polyethylene glycol (PEG). Moreover, several protectant substances at different concentrations were evaluated. Modification of lower a w ‐levels (0.721–0.901) with glycerol did not maintain the viability of the yeast cells. Higher a w ‐levels (0.93–0.95) with either glycerol or PEG improved the viability but not at acceptable viability levels. C. sake cells maintained viabilities >60% when sugars, such as trehalose, and polyols, such as glycerol and PEG were used as protectants in liquid formulations. Moreover, liquid formulations of C. sake stored at 4°C showed higher number of viable counts than at 20°C. When different sugars were tested, all of them, except 10% fructose, resulted in a viability higher than 50% of the C. sake formulations. Biocontrol of liquid formulation treatments was similar to fresh cells in controlling Penicillium expansum on wounded apples. Conclusions: Sugars such as lactose and trehalose could be considered as good protectants in order to obtain liquid formulations of C. sake cells as they maintain the viability >70% for 4 months at 4°C. Significance and Impact of Study: This study shows that a suitable liquid formulation for commercial application can be produced with high viability and conservation of biocontrol efficacy. Moreover, if 10% lactose is the protectant used in the formulation, the economic costs would not be limiting for industrial production.