title: Shelf-life evaluation of natural antimicrobials for Concord and Niagara grape juices.
abstract: This study was conducted to evaluate the effectiveness of natural antimicrobials for shelf-life extension of cold-filled still and carbonated Concord and Niagara grape juices, which have traditionally been preserved with chemical preservatives. Commercial juices were inoculated with  a spoilage yeast cocktail of Dekkera, Kluveromyces, Brettanomyces, and Zygosaccharomyces at 10(2) and 10(4) CFU/ml. The following agents were added to still juices: no preservative (negative control), 0.05% potassium sorbate plus 0.05% sodium benzoate (positive  control), 0.1 or 0.2% cultured dextrose, 250 ppm of dimethyldicarbonate (DMDC), 10 or 20 ppm of natamycin, and 250 ppm of DMDC plus 5 or 10 ppm of natamycin. Carbonated juice was treated with the negative control, positive control, and 250 ppm of DMDC plus 10 ppm of natamycin. Microbial stability  of samples was assessed every 2 weeks during 6 months of storage at 21°C by yeast enumeration and measurement of turbidity, pH, and °Brix. Juices were deemed spoiled when yeast counts exceeded 10(6) CFU/ml. Cultured dextrose was not effective at levels tested in both types  of juice. The most promising results were obtained with DMDC and natamycin combination treatments in still Niagara juice and in carbonated Concord and Niagara juices. In these treatments, shelf-life extension similar to that of the positive control (153 to 161 days) was achieved while maintaining  similar turbidity, pH, and °Brix. Spoiled juices had lower pH and °Brix values and higher turbidity due to microbial activity and increased in microbial levels.
authors: Department of Food Science, Cornell University, New York State Agricultural Experiment Station, Geneva, New York 14456, USA.
authors: P
authors: P
authors: Siricururatana
authors: M M
authors: MM
authors: Iyer
authors: D C
authors: DC
authors: Manns
authors: J J
authors: JJ
authors: Churey
authors: R W
authors: RW
authors: Worobo
authors: O I
authors: OI
authors: Padilla-Zakour
mesh_terms: D001628:Beverages / Q000382:microbiology*; D002253:Carbonated Beverages / Q000382:microbiology; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004305:Dose-Response Relationship, Drug; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D005519:Food Preservation / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D013997:Time Factors; D027843:Vitis / Q000382:microbiology; D015003:Yeasts / Q000187:drug effects* / Q000254:growth & development*
chemical_list: D005520:Food Preservatives