分段发酵模式对郫县豆瓣甜瓣子发酵过程中微生物及产品品质的影响

分别建立2 种“先低盐后高盐、先低温后高温”的分段发酵模式，其中模式1发酵条件为前期食盐质量分数为6%，12 ℃发酵12 d；中期食盐质量分数为6%，37 ℃发酵4 d；后期食盐质量分数为15%，37 ℃发酵14 d。模式2发酵前期和中期食盐质量分数为9%，其余条件与模式1相同。以传统高温发酵为对照，监测发酵过程中霉菌总数、细菌总数及理化指标的变化规律，并对发酵结束的甜瓣子样品进行生物胺和挥发性成分分析。结果表明，分段发酵（模式1、模式2）中霉菌和细菌总数都呈先保持相对稳定后快速下降的变化趋势，而对照组中霉菌总数随着发酵的进行其数量不断下降，细菌总数则先下降后缓慢增加至稳定。发酵结束时，模式1、模式2和对照组甜瓣子中总酸质量分数分别为0.96%、0.92%、0.87%，氨基酸态氮质量分数分别为0.76%、0.83%、0.66%，生物胺含量分别为122.93、126.50、176.12 mg/kg。此外，模式1和模式2发酵甜瓣子中挥发性成分种类和含量均高于对照组，其中模式1中挥发性成分含量最高，特别是酯类化合物。感官评价显示，模式1发酵甜瓣子的感官品质最佳，模式2次之，对照组最差。综合分析可知，分段发酵（模式1、模式2）甜瓣子品质优于传统高温发酵甜瓣子，尤其是模式1。     

不同五粮配方的成分解析及其酿造特性对比研究

该研究对3种五粮配方（陈氏秘方、经典五粮配方、新五粮配方）和8种粮食的理化指标进行解析，分析各理化指标与酿酒性能的相关性。同时，以3种五粮配方酿造白酒，采用顶空-固相微萃取（HS-SPME）结合气质联用（GC-MS）法分析酒样中的挥发性风味成分，研究其酿造特性。结果表明，8种粮食的淀粉微粒结构各有差别，是造成其淀粉性质差异的重要原因。大米的总淀粉含量最高（74.04%）；小米、糯米和糯高粱的支链淀粉含量较高，对产酒生香有益；大米、糯米和玉米的蛋白质含量均＜8%，其他均＞10%；玉米的粗脂肪含量最高（4.61%），作为单粮发酵可能会影响酒质。3种配方的淀粉含量都＞66%，蛋白质和粗脂肪的含量适中，其中陈氏秘方的支链淀粉含量最高，更适合发酵生香；且酒样中挥发性成分种类最多，共39种，更适合用于白酒发酵生产。     

The Delta 5,7-Sterols and Astaxanthin in the Marine Microheterotroph Schizochytrium sp. S31

The thraustochytrids, the heterotrophic marine microorganisms, have received increasing attention because of their capacity for the production of high-value products such as docosahexaenoic acid (DHA), carotenoids, and sterols. In this study, three potential Δ^5,7-sterols, showing similar UV absorption spectra to that of ergosterol, in the thraustochytrid Schizochytrium sp. S31, were estimated by the ultraperformance liquid chromatography (UPLC) − APCI−MS/MS method. The proposed structures of three Δ^5,7-sterols were ergosta-5,7,24(28)-trien-3β-ol, ergosta-5,7-dien-3β-ol, and 24-ethylcholesta-5,7,22-trien-3β-ol. The contents of astaxanthin, ergosterol, and the other three Δ^5,7-sterols in Schizochytrium sp. S31 during the cultivation performed in three separate batches were analyzed by a fast UPLC–PDA method. The results demonstrated that astaxanthin, ergosterol, and ergosta-5,7-dien-3β-ol were the predominant carotenoid and Δ^5,7-sterols, respectively, and their contents kept increasing during the growth and reached a maximum after 23 days of cultivation. The estimated maximum contents of astaxanthin and four Δ^5,7-sterols, including ergosterol, ergosta-5,7-dien-3β-ol, ergosta-5,7,24(28)-trien-3β-ol, and 24-ethylcholesta-5,7,22-trien-3β-ol were 2.31, 4.02, 3.43, 0.30, and 0.97 mg g⁻¹ dry biomass, respectively. These findings are different to other strains reported in the composition and accumulation of Δ^5,7-sterols and carotenoids. The present study suggests that Schizochytrium sp. S31 might be a promising marine microorganism for the productions of high-value natural pigment astaxanthin, the provitamin D₂ ergosterol, and the provitamin D₄ ergosta-5,7-dien-3β-ol, and taken as a model organism to study the sterologenesis of the microorganisms because of its complexity of sterol compositions.     

Simultaneous effects of radiation,magnetic field on peristaltic flow of Carreau nanofluid submerged in gyrotactic microorganisms with heat and mass transfer

Our study intends to examine the combined effects of radiation, magnetic field, and chemical reaction on the peristaltic flow of a non-Newtonian fluid containing gyrotactic microorganisms and nanoparticles. The system of our equations is understood numerically by using the Rung-Kutta-Merson method with Newton iteration in a shooting and matching procedure. The effect of physical implanted parameters is represented and discussed through a lot of charts for velocity, temperature, nanoparticle concentration, the density of motile microorganisms. From this discussion, we notice that the motile microorganisms profile is affected by the arising with the Brownian motion parameter and radiation parameter but the thermophoresis parameter, traditional Lewis number, and bioconvection of Peclet number are decremented the motile microorganisms profile.     

浓香型白酒酒醅微生物与酯类成分关联性定量模型的建立

为研究浓香型白酒出窖酒醅微生物与酯类成分的定量关系，该研究通过高通量测序分析浓香型白酒出窖酒醅优势微生物属的相对丰度，使用气相色谱-质谱联用法（GC-MS）测定酒醅中主要酯类成分的相对含量，并以优势微生物属为自变量，主要酯类物质为因变量，对建模变量进行两轮筛选，建立两者的偏最小二乘（PLS）数学模型。结果表明，经变量筛选后得到的模型包含11种酯类物质和16种优势微生物属；模型主成分个数为3时，所保留的变量均能够用选取的主成分进行解释；所得模型能够解释92.6%的自变量信息和89.4%的因变量信息，预测率为0.679，质量良好，该模型可以定量解释出窖酒醅微生物与酯类之间的关联性。     

XAD Resins for Increased Rebeccamycin Productivity in Cultivations of Lentzea aerocolonigenes

Lentzea aerocolonigenes produces the antitumor antibiotic rebeccamycin. For a medical application maximized titers and appropriate downstream processing are necessary. The addition of the adsorbents XAD 4, XAD 17 HP, and XAD 16 N was investigated for increased productivity and in situ product recovery. An increase in product titer was observed for XAD 7 HP and XAD 16 N. A combination of these particles with glass beads led to a further increase. Moreover, rebeccamycin can be adsorbed to these particles which facilitate the extraction since the liquid phase can be dispensed with.     

MALDI-TOF:是否可作为啤酒厂微生物实验室的日常检测手段

饮料厂和啤酒厂的生产以及灌装的复杂程度在逐渐增加。随之而来的,人们对可靠的、尽量快速的微生物检测方法的需求程度也在加强,啤酒厂实验室对此义不容辞。在此前提下,Warsteiner酿酒集团的中心实验室将一种新的借助MALDI-TOF(基质辅助激光解吸电离飞行时间质谱)的检测方法与长久以来已经存在的PCR检测法进行了一个对比。     

鸡蛋壳暗斑对鸡蛋贮藏性能的影响

文章探讨了鸡蛋壳具有0%,10%,30%,60%的暗斑覆盖率对贮藏中鸡蛋失重率、相对密度、蛋黄指数、蛋清pH值、哈夫单位等新鲜度指标及菌落总数、大肠菌群、霉菌、沙门氏菌等微生物的影响。结果表明,在鸡蛋存放期间,暗斑鸡蛋新鲜度指标的变化速度以及菌落总数、霉菌等微生物的增长速度均较无斑鸡蛋快,且随着鸡蛋壳暗斑覆盖率的增加,鸡蛋新鲜度下降越快,菌落总数、霉菌等微生物的增长也越快。鸡蛋壳暗斑的存在对鸡蛋品质具有不良影响,可使鸡蛋贮藏期缩短。