Effects of non-thermal plasma treating wheat kernel on the physicochemical properties of wheat flour and the quality of fresh wet noodles

The effects of non-thermal plasma (NTP) on the physicochemical properties of wheat flour and the quality of fresh wet noodles ( FWN) were investigated. The results showed that NTP effectively decreased the total plate count (TPC), yeast and mould count (YMC) and Bacillus spp. in wheat flour. Wet gluten contents and the stability time reached the maximum when treated for 20 s. The viscosity of starch increased significantly after treatment due to the increased of damaged starch. The contents of secondary structure were altered to some extent, which was because that the ordered network structure of gluten protein broken. Furthermore, compared with the control, texture properties of FWN were enhanced significantly at 20 s, and the darkening rate of FWN was greatly inhibited due to the low polyphenol oxidase (PPO) activity. Consequently, the most suitable treatment was 500 W for 20 s, providing a basis for the application of NTP in flour products.     

无黏土相盐水储层钻开液体系构建及其抗污染性能评价

采用NaCl/KCl/HCOONa复配欠饱和盐水作为钻开液的基础液相,自研的聚合物VIS-B作为流型调节剂,可酸溶的改性淀粉STA作为体系的降失水剂,Dua及Jqw作为暂堵材料,构建了一套无黏土相钻开液体系。该体系在密度1.10~1.28 g/cm^3间稳定可调,抗温可达130℃,具有较高的低剪切速率黏度和较好的润滑性能,且能有效抵抗各类储层污染物的污染,满足了Missan油田不同储层段的作业需求。     

生姜猕猴桃自然酒精发酵醪微生物多样性研究

为了探讨和评估生姜猕猴桃自然酒精发酵醪酵母菌系多样性及其产品的安全性，采用微生物可培养方法对生姜猕猴桃自然酒精发酵中的酵母菌进行分离，并利用5.8S rDNA ITS序列信息分析不同时期生姜猕猴桃自然酒精发酵醪的酵母菌株α多样性和β多样性。结果表明，生姜猕猴桃自然酒精发酵中酵母菌有8属11种，包括假丝酵母、孢汉逊酵母、德巴利酵母、毕赤酵母、伊萨酵母、柯达酵母、梅奇酵母、Meyerozyma。毕赤酵母是生姜猕猴桃自然酒精发酵醪初期和后期的优势酵母菌群，Myerozyma是生姜猕猴桃自然酒精发酵醪初期和中期的优势酵母菌群。α多样性、β多样性分析结果显示，生姜猕猴桃自然酒精发酵中期物种多样性最高，发酵后期酵母菌数与独有酵母菌数最多，物种丰富度最高。     

Effective sampling strategy to detect food and feed contamination: Herbs and spices case

Sampling plans for food safety hazards are aimed to be used to determine whether a lot of food is contaminated (with microbiological or chemical hazards) or not. One of the components of sampling plans is the sampling strategy. The aim of this study was to compare the performance of three different sampling strategies, being simple random sampling (SRS), stratified random sampling (STRS), and systematic sampling (SS), with each other for their probability of detecting a heterogeneously distributed contamination in a lot of herbs or spices (i.e., a dry food product). To this end, a simulation model was developed, and applied to different scenarios for contamination level and numbers of samples collected. In addition, as a case study, the sampling plan of a company processing herbs and spices was evaluated using the simulation model. Results showed that the effectiveness of the sampling plan is influenced by the sampling strategy. With expected low contamination levels the SS strategy performs better than the two other strategies. At higher expected contaminated levels, the STRS strategy is preferred.     

常压室温等离子诱变与微生物微滴培养选育几丁质脱乙酰基酶高产菌株

该研究将室温等离子（ARTP）诱变与微生物微滴培养（MMC）技术应用于几丁质脱乙酰基酶（CDA）高产菌株的诱变选育，构建高产CDA菌株的诱变及高通量筛选方法。结果表明，经过4轮的ARTP诱变及MMC筛选，从200个不同的液滴中共筛选出5个发酵产酶明显提升的液滴，并通过进一步的平板筛选、24-深孔板复筛，获得了17株产酶提高300%以上的诱变菌株。通过对比分析17株高产菌株产CDA的能力，确定了1株最佳CDA高产菌株B4，其CDA最大产量比出发菌株提高了3.15倍，发酵产酶总量达到419.11 U/mL，为原始菌种的3.90倍。该研究为CDA高产菌株的诱变选育及高通量筛选提供了借鉴。     

Airborne bacterial assemblage in a zero carbon building: A case study

Currently, there is little information pertaining to the airborne bacterial communities of green buildings. In this case study, the air bacterial community of a zero carbon building (ZCB) in Hong Kong was characterized by targeting the bacterial 16S rRNA gene. Bacteria associated with the outdoor environment dominated the indoor airborne bacterial assemblage, with a modest contribution from bacteria associated with human skin. Differences in overall community diversity, membership, and composition associated with short (day‐to‐day) and long‐term temporal properties were detected, which may have been driven by specific environmental genera and taxa. Furthermore, time‐decay relationships in community membership (based on unweighted UniFrac distances) and composition (based on weighted UniFrac distances) differed depending on the season and sampling location. A Bayesian source‐tracking approach further supported the importance of adjacent outdoor air bacterial assemblage in sourcing the ZCB indoor bioaerosol. Despite the unique building attributes, the ZCB microbial assemblage detected and its temporal characteristics were not dissimilar to that of conventional built environments investigated previously. Future controlled experiments and microbial assemblage investigations of other ZCBs will undoubtedly uncover additional knowledge related to how airborne bacteria in green buildings may be influenced by their distinctive architectural attributes.