Rosenkvist H, Hansen A
Royal Veterinary and Agricultural University, Centre for Food Research, Frederiksberg, Denmark.
Int J Food Microbiol. 1995 Aug;26(3):353-63. doi: 10.1016/0168-1605(94)00147-x.
The Bacillus counts in white and wholemeal wheat loaves produced without preservatives or sour dough were consistently 10(6) cfu/g after two days of storage at ambient summer temperatures (25-30 degree C). Identified species were B. subtilis (70%), B. licheniformis (24%), B. pumilus (2%) and B. cereus (2%). The dominance of B. subtilis in bread could be explained by the higher resistance to heat of this species as determined by inoculation studies. Among 14 species isolated from retail bread and wheat grains, B. subtilis was the only species associated with ropiness. Samples of raw materials, particularly bran, seeds and oat products, contained low levels (10(0) - 10(2) cfu/g) of Bacillus spores, surviving a heat treatment (100 degree C, 10 min) corresponding to a baking process. Even low spore levels in raw materials with the frequently isolated species, B. licheniformis (49%) and B. subtilis (10%), resulted in 10(7) Bacillus per g bread crumb in two days as determined by test bakings. The results indicate a need for controlling growth of Bacillus in bread.
在夏季常温（25 - 30摄氏度）下储存两天后，未添加防腐剂或酸面团制作的白面包和全麦面包中的芽孢杆菌数量始终为10⁶ cfu/g。鉴定出的菌种有枯草芽孢杆菌（70%）、地衣芽孢杆菌（24%）、短小芽孢杆菌（2%）和蜡样芽孢杆菌（2%）。接种研究表明，枯草芽孢杆菌在面包中占主导地位的原因可能是该菌种对热的耐受性更强。在从零售面包和小麦谷物中分离出的14个菌种中，枯草芽孢杆菌是唯一与面包发粘有关的菌种。原材料样本，特别是麸皮、种子和燕麦产品，含有低水平（10⁰ - 10² cfu/g）的芽孢杆菌孢子，这些孢子在相当于烘焙过程的热处理（100摄氏度，10分钟）后仍存活。通过试验烘焙测定，即使原材料中经常分离出的地衣芽孢杆菌（49%）和枯草芽孢杆菌（10%）孢子水平较低，两天后每克面包屑中也会有10⁷个芽孢杆菌。结果表明有必要控制面包中芽孢杆菌的生长。
