我国传统食醋常采用开放式发酵工艺生产,参与的微生物复杂多样,生产过程控制不当易导致产品微生物污染。本论文比较分析了正常食醋(NV)和胀气食醋(ANV)样品的理化指标与活菌数等差异,并分析了ANV中主要气体成分,分离鉴定了食醋中潜在的...我国传统食醋常采用开放式发酵工艺生产,参与的微生物复杂多样,生产过程控制不当易导致产品微生物污染。本论文比较分析了正常食醋(NV)和胀气食醋(ANV)样品的理化指标与活菌数等差异,并分析了ANV中主要气体成分,分离鉴定了食醋中潜在的污染微生物。结果表明,ANV中活菌数超标,还原糖和总糖含量降低,乳酸含量升高。ANV样品顶空部分二氧化碳浓度超过0.005,导致胀气的主要成分是二氧化碳。从ANV食醋样品中分离到30株细菌,其中16株具有耐热、产气及耐防腐剂等特性,是导致食醋污染的潜在微生物。16S r DNA测序分析表明16株菌分别属于Bacillus,Pseudomonas,Stenotrophomonas,Serratia,Clostridium,Aneurinibacillus,Brevibacillus,Sphinqobacterium,Delftia等8个属。其中菌株PMB-9和PMB-16发酵液中产生白色絮状物,发酵液变粘稠,是导致食醋粘稠的潜在污染微生物,菌株PMB-3、PMB-4、PMB-7、PMB-8和PMB-14能够在食醋中生长并产生气体,是导致食醋胀气的潜在污染微生物。展开更多
This research reported the effect of peeling naked oats with a peeling machine equipped with the flexible alloy blade.Results showed that the flexible alloy blade could achieve the same effect as traditional abrasive ...This research reported the effect of peeling naked oats with a peeling machine equipped with the flexible alloy blade.Results showed that the flexible alloy blade could achieve the same effect as traditional abrasive rolls. Furthermore, the new peeling method had hardly damage to the oat kernels. The result of scanning electron microscopy indicated the surface of peeled naked oats by the flexible alloy blade is homogeneous. The gap between the flexible alloy blade and the slotted screen could change the particle sizes of the flours obtained, which differed from traditional peeling machines. In addition, peeling for 15 seconds significantly reduced the microbial contaminants. The removal of outer layer decreased the lipase activity. The technological parameters were optimized by orthogonal L_9(3~4) test, the results showed a 30 s peeling time and 2% second-addition of water contributed to the peeling rate. The texture analysis demonstrate that the hardness of cooked groats decreases obviously after peeling treatments.展开更多
Inspired by iron fertilization experiments in HNLC（high-nitrate, low-chlorophyll） sea areas,we proposed the use of iron-rich engineered microalgae for microbial contaminant control in iron-free culture media. Based ...Inspired by iron fertilization experiments in HNLC（high-nitrate, low-chlorophyll） sea areas,we proposed the use of iron-rich engineered microalgae for microbial contaminant control in iron-free culture media. Based on the genome sequence and natural transformation system of Synechocystis sp. PCC6803, ftn A（encoding ferritin） was selected as our target gene and was cloned into wild-type Synechocystis sp. PCC6803. Tests at the molecular level confirmed the successful construction of the engineered Synechocystis sp. PCC6803-ftn A. After Fe3＋-EDTA pulsing, the intracellular iron content of Synechocystis sp. PCC6803-ftn A was significantly enhanced, and the algae was used in the microbial contamination control system. In the coupled Synechocystis sp. PCC6803-ftn A production and municipal wastewater（MW, including Scenedesmus obliquus and Bacillus） treatment, Synechocystis sp. PCC6803-ftn A accounted for all of the microbial activity and significantly increased from 70% of the microbial community to 95%.These results revealed that while the stored iron in the Synechocystis sp. PCC6803-ftn A cells was used for growth and reproduction of this microalga in the MW, the growth of other microbes was inhibited because of the iron limitation, and these results provide a new method for microbial contamination control during a coupling process.展开更多
文摘我国传统食醋常采用开放式发酵工艺生产,参与的微生物复杂多样,生产过程控制不当易导致产品微生物污染。本论文比较分析了正常食醋(NV)和胀气食醋(ANV)样品的理化指标与活菌数等差异,并分析了ANV中主要气体成分,分离鉴定了食醋中潜在的污染微生物。结果表明,ANV中活菌数超标,还原糖和总糖含量降低,乳酸含量升高。ANV样品顶空部分二氧化碳浓度超过0.005,导致胀气的主要成分是二氧化碳。从ANV食醋样品中分离到30株细菌,其中16株具有耐热、产气及耐防腐剂等特性,是导致食醋污染的潜在微生物。16S r DNA测序分析表明16株菌分别属于Bacillus,Pseudomonas,Stenotrophomonas,Serratia,Clostridium,Aneurinibacillus,Brevibacillus,Sphinqobacterium,Delftia等8个属。其中菌株PMB-9和PMB-16发酵液中产生白色絮状物,发酵液变粘稠,是导致食醋粘稠的潜在污染微生物,菌株PMB-3、PMB-4、PMB-7、PMB-8和PMB-14能够在食醋中生长并产生气体,是导致食醋胀气的潜在污染微生物。
基金Supported by National Natural Science Foundation of China(No.31571873)National College Students Innovation and Entrepreneurship Training Program Project(201710463002)
文摘This research reported the effect of peeling naked oats with a peeling machine equipped with the flexible alloy blade.Results showed that the flexible alloy blade could achieve the same effect as traditional abrasive rolls. Furthermore, the new peeling method had hardly damage to the oat kernels. The result of scanning electron microscopy indicated the surface of peeled naked oats by the flexible alloy blade is homogeneous. The gap between the flexible alloy blade and the slotted screen could change the particle sizes of the flours obtained, which differed from traditional peeling machines. In addition, peeling for 15 seconds significantly reduced the microbial contaminants. The removal of outer layer decreased the lipase activity. The technological parameters were optimized by orthogonal L_9(3~4) test, the results showed a 30 s peeling time and 2% second-addition of water contributed to the peeling rate. The texture analysis demonstrate that the hardness of cooked groats decreases obviously after peeling treatments.
基金supported by the National Key Technologies R&D Program of China(No.2012BAJ25B02)
文摘Inspired by iron fertilization experiments in HNLC（high-nitrate, low-chlorophyll） sea areas,we proposed the use of iron-rich engineered microalgae for microbial contaminant control in iron-free culture media. Based on the genome sequence and natural transformation system of Synechocystis sp. PCC6803, ftn A（encoding ferritin） was selected as our target gene and was cloned into wild-type Synechocystis sp. PCC6803. Tests at the molecular level confirmed the successful construction of the engineered Synechocystis sp. PCC6803-ftn A. After Fe3＋-EDTA pulsing, the intracellular iron content of Synechocystis sp. PCC6803-ftn A was significantly enhanced, and the algae was used in the microbial contamination control system. In the coupled Synechocystis sp. PCC6803-ftn A production and municipal wastewater（MW, including Scenedesmus obliquus and Bacillus） treatment, Synechocystis sp. PCC6803-ftn A accounted for all of the microbial activity and significantly increased from 70% of the microbial community to 95%.These results revealed that while the stored iron in the Synechocystis sp. PCC6803-ftn A cells was used for growth and reproduction of this microalga in the MW, the growth of other microbes was inhibited because of the iron limitation, and these results provide a new method for microbial contamination control during a coupling process.
