Department of Food Science, Cornell University, New York State Agricultural Experiment Station, Geneva, New York 14456, USA.
J Food Prot. 2013 Jan;76(1):72-8. doi: 10.4315/0362-028X.JFP-12-144.
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.
本研究旨在评估天然抗菌剂对冷填充静止和碳酸化康科德和尼亚加拉葡萄汁的货架期延长的效果，这些果汁传统上使用化学防腐剂保存。商业果汁用 10(2)和 10(4)CFU/ml 的腐败酵母鸡尾酒（Dekkera、Kluveromyces、Brettanomyces 和 Zygosaccharomyces）接种。向静止果汁中添加以下试剂：无防腐剂（阴性对照）、0.05%山梨酸钾加 0.05%苯甲酸钠（阳性对照）、0.1 或 0.2%培养的右旋糖、250ppm 二甲基二碳酸盐（DMDC）、10 或 20ppm 纳他霉素以及 250ppm DMDC 加 5 或 10ppm 纳他霉素。碳酸化果汁用阴性对照、阳性对照和 250ppm DMDC 加 10ppm 纳他霉素处理。在 21°C 下储存 6 个月期间，每两周通过酵母计数和浊度、pH 值和 °Brix 的测量评估样品的微生物稳定性。当酵母计数超过 10(6)CFU/ml 时，认为果汁变质。在两种类型的果汁中测试的浓度下，培养的右旋糖都没有效果。在静止尼亚加拉果汁以及碳酸化康科德和尼亚加拉果汁中，DMDC 和纳他霉素联合处理效果最显著。在这些处理中，虽然保持了相似的浊度、pH 值和 °Brix，但实现了与阳性对照（153 至 161 天）相似的货架期延长。变质果汁由于微生物活性和微生物水平的增加，具有较低的 pH 值和 °Brix 值以及较高的浊度。
