Dept of Food Science and Human Nutrition, Univ of Illinois at Urbana-Champaign, 1304 W Pennsylvania Ave, Urbana, IL 61801, USA.
J Food Sci. 2012 Feb;77(2):M121-6. doi: 10.1111/j.1750-3841.2011.02553.x. Epub 2012 Feb 6.
It has been reported that washing seeds with a 20000 ppm Ca(OCl)(2) solution as recommended by the U.S. Food and Drug Administration is unable to eliminate E. coli cells attached to seed surfaces, and the bacterial cells that have survived a sanitation wash can proliferate during sprouting to a high population. The objectives of this research were to examine the efficacy of malic acid (MA) and thiamine dilauryl sulfate (TDS) combined treatments on the inactivation of E. coli O157:H7 on alfalfa seeds, to study the growth of the remaining E. coli cells during sprouting, and to evaluate the sprout quality. When 10 g of inoculated alfalfa seeds were washed in a 10% MA-1% TDS solution, a complete elimination of E. coli was achieved. The same result was observed by washing the seeds in a 20000 ppm Ca(OCl)(2) solution. However, when the seed size was increased to 50 g while maintaining the same seed-to-sanitizer ratio, both the MA + TDS and the 20000 ppm chlorine washes failed to completely inactivate the E. coli cells on the seeds. Nevertheless, the 10% MA-1% TDS solution was significantly more effective in E. coli count reduction compared to the 20000 ppm chlorine wash. The E. coli O157:H7 cells remaining on the seeds after treatments with both sanitizers grew up to 7 to 8 log CFU/g sprout after 96 h of sprouting. Under the treatment conditions used in this study, none of the treatments resulted in significant differences in germination rate, yield, or quality of the sprouts.
The malic acid (MA) and thiamine dilauryl sulfate (TDS) combined treatment may provide a new solution to secure the microbial safety of seeds and sprouts. An important finding of this study is that seed sample size has a significant impact on the inactivation of E. coli O157:H7 on alfalfa seeds. The microbial inactivation results obtained in a laboratory set-up cannot be directly applied to a large scale operation. A validation test on the large scale has to be performed to evaluate the efficacy of the sanitizer.
据报道，按照美国食品和药物管理局的建议，用 20000ppm 的次氯酸钙（Ca（OCl）（2））溶液清洗种子，无法消除附着在种子表面的大肠杆菌细胞，并且在卫生清洗后幸存下来的细菌细胞在发芽期间会大量繁殖。本研究的目的是研究苹果酸（MA）和硫代双月桂酸酯（TDS）联合处理对苜蓿种子上大肠杆菌 O157：H7 的灭活效果，研究发芽过程中剩余大肠杆菌细胞的生长情况，并评价芽的质量。当 10g 接种的苜蓿种子在 10% MA-1% TDS 溶液中洗涤时，完全消除了大肠杆菌。用 20000ppm 的次氯酸钙溶液洗涤也观察到相同的结果。然而，当种子大小增加到 50g 时，同时保持相同的种子与消毒剂的比例，MA+TDS 和 20000ppm 氯洗涤都不能完全灭活种子上的大肠杆菌细胞。然而，10% MA-1% TDS 溶液在减少大肠杆菌计数方面明显比 20000ppm 氯洗涤更有效。在用两种消毒剂处理后留在种子上的大肠杆菌 O157：H7 细胞在发芽 96 小时后可生长至 7 至 8logCFU/g 芽。在本研究中使用的处理条件下，处理对发芽率、产量或芽质量没有显著影响。
苹果酸（MA）和硫代双月桂酸酯（TDS）联合处理可能为确保种子和芽的微生物安全提供新的解决方案。本研究的一个重要发现是，种子样品的大小对苜蓿种子上大肠杆菌 O157：H7 的灭活有显著影响。在实验室设置中获得的微生物失活动力学结果不能直接应用于大规模操作。必须在大规模上进行验证试验，以评估消毒剂的功效。
