Guelph Research and Development Center, Agriculture and Agri-Food Canada, Guelph, Ontario N1G 5C9, Canada.
Guelph Research and Development Center, Agriculture and Agri-Food Canada, Guelph, Ontario N1G 5C9, Canada.
Food Res Int. 2021 Feb;140:110085. doi: 10.1016/j.foodres.2020.110085. Epub 2020 Dec 29.
Ultraviolet-C (UV-C) light is a non-thermal method for improving the safety and shelf-life of cold-pressed juices with minimal impact on quality and nutrition. Most previous studies have investigated fruit juices as opposed to particulate dense leafy green juices with very low UV transmittance (UVT). Pure kale juice is a common juice ingredient and represents the worst-case scenario in terms of low UVT green juices. This study validated the use of continuous benchtop UV-C treatment at 253.7 nm for 5-log reduction of non-pathogenic Escherichia coli P36 in kale juice. An average absorbed fluence of 108.3 mJ cm resulted in a 5.8 log reduction of E. coli P36. At a fluence comparable to that reported for commercial juice processing (74.0 mJ cm), kale juice exhibited a decrease in absorption coefficient, while sedimentation, supernatant browning and pectin methylesterase activity increased with no effect on the chlorophyll content, colour, viscosity or antioxidant content.
紫外线-C（UV-C）光是非热方法，可用于提高冷压果汁的安全性和保质期，对质量和营养的影响最小。大多数先前的研究都针对果汁，而不是颗粒状的浓稠绿叶蔬菜汁，其紫外线透射率（UVT）非常低。纯羽衣甘蓝汁是一种常见的果汁成分，是低 UVT 绿色果汁中最差的情况。本研究验证了在 253.7nm 下使用连续台式 UV-C 处理，可将非致病性大肠杆菌 P36 在羽衣甘蓝汁中的数量减少 5 个对数级。平均吸收剂量为 108.3mJ/cm，可使大肠杆菌 P36 减少 5.8 个对数级。在与商业果汁加工（74.0mJ/cm）报告的剂量相当的情况下，羽衣甘蓝汁的吸收系数下降，而沉淀、上清液褐变和果胶甲酯酶活性增加，对叶绿素含量、颜色、粘度或抗氧化剂含量没有影响。
