三七渣固态发酵生产蛋白饲料的动力学

对白腐菌(Phanerochaete Chrysosporium 5.776)/产朊假丝酵母(Candida utilis 2.281)固态发酵三七渣生产蛋白饲料的过程进行了研究,并建立了菌体生长和淀粉降解动力学模型。结果表明,以发酵培养物干基减重率作为表达菌体浓度的间接参数,菌体生长动力学适合采用对数模型进行描述,发酵培养物最大干基减重率Xm=49.68%,比生长速率常数μ=0.042 90 h-1。菌体生长速率在发酵84.8 h后达到最大值。淀粉的降解动力学适合采用指数模型进行描述,发酵过程中淀粉含量降低了26%,降解速率常数为0.015 9 h-1,淀粉的降解速率随着发酵时间的延长而逐渐变小。     

三七渣固态发酵生产蛋白饲料

以三七渣为原料,利用康宁木霉固态发酵生产蛋白饲料,考察了培养条件对康宁木霉固态发酵三七渣的影响,采用正交试验优化了发酵条件.研究结果表明,最佳发酵条件为氮源添加量为40mg硫酸铵/g干药渣、固液比1.0:1.5、发酵时间5d、原料粒径80目,在上述发酵条件下,三七渣中真蛋白含量由9.97%提高至19.40%,粗纤维含量从27.45%降低至11.91%.     

三七渣混菌发酵生产蛋白饲料的初步研究

本次研究考察了培养基制备条件对黑曲霉/产朊假丝酵母固态发酵三七渣生产蛋白饲料的影响,并采用正交试验对培养基制备条件进行了优化.研究结果表明,在培养基制备过程中,氮源添加量、水含量和粒径3个因素对发酵培养物中真蛋白含量影响较大;磷源添加量、pH值和Tween-80添加量3个因素对其影响不显著.三七渣需要进行粉碎过筛、适量的补充氮源和调整含水量等预处理后才适合作为固态发酵培养基使用,优化的三七渣培养基制备条件为采用经粉碎后过60目筛的三七渣,添加5％的硫酸铵,基质含水量70％,pH值自然.     

混菌发酵三七渣生产蛋白饲料的菌种组合优化研究

分别采用5种多糖分解菌和3种酵母菌搭配组合进行了混菌发酵三七渣生产蛋白饲料的菌种组合优化研究,研究结果表明,以发酵培养物中的粗蛋白含量为评价指标,多糖分解菌对试验结果的影响强于酵母菌,多糖分解菌和酵母菌之间的交互作用显著(p<0.05)。黑曲霉与酵母菌混菌发酵的试验结果显著优于其他多糖分解菌与酵母菌混菌发酵的试验结果。黑曲霉与3种酵母菌混菌发酵的试验结果没有显著差异(p>0.05)。     

不同菌种以三七渣为基质的发酵过程

为了选择合适的菌种用于三七渣固态发酵生产蛋白饲料,分别进行了黑曲霉、康宁木霉、米曲霉、绿色木霉、白腐菌共5种多糖分解菌和产朊假丝酵母、热带假丝酵母、酿酒酵母共3种酵母菌以三七渣为基质的发酵过程研究。研究结果表明,多糖分解菌对三七渣的代谢能力明显强于酵母菌,在发酵过程中多糖分解菌发酵培养物的还原糖质量浓度、pH值、干重变化幅度均大于酵母菌。在所有受试菌种中黑曲霉对三七渣的代谢能力最强,其发酵培养物中还原糖质量浓度峰值可达250 mg/g,经过5 d发酵后黑曲霉发酵培养物的干基减重率达42.6%,真蛋白质量分数达到23.92%。     

紫色红曲霉固态发酵三七渣生产红色素的动力学研究

该实验在紫色红曲霉固态发酵三七渣生产红色素过程中考察了生物量、淀粉含量、总糖含量、还原糖含量、红色素色价和pH等参数随时间的变化情况,并建立了菌体生长、基质降解和产物生成的动力学模型。结果表明,菌体生长、基质降解和产物生成动力学分别适合采用对数模型、四参数对数模型、Boltzmann模型进行描述。最大菌体生物量Xm为0.241 6 g/g发酵培养物（干基）,比生长速率常数μ为0.457 4 d-1。最大红色素色价B2为14.63 U/g发酵培养物（干基）,红色素色价达到最大值一半时需要的发酵时间t0=4.21 d。发酵末期发酵培养物（干基）中总糖含量D2为28.84%,总糖降解的半衰期t50%为3.536 d。     

发酵苹果渣生产菌体蛋白饲料工艺的研究

以热带假丝酵母菌和啤酒酵母菌为发酵剂,研究了发酵果渣生产菌体蛋白饲料的影响条件,混合菌种发酵生产的蛋白质含量优于单菌发酵,加入氮源处理较无氮源处理的蛋白质含量高.发酵初步确定了果渣固态发酵的适宜条件,即发酵温度为32℃,物料质量比(果渣:麸皮)为85:15(水分含量在660g/kg),发酵料投放量为100g,采用自然pH值,发酵周期为60h左右.发酵产品的粗蛋白含量由20.10%提高到29.30%,粗脂肪和灰分含量也大幅提高,营养价值得到了全面改善.     

固态发酵马铃薯渣生产菌体蛋白饲料的研究

以马铃薯淀粉生产中产生的废渣为主要原料,以黑曲霉、白地霉和热带假丝酵母为发酵菌种,优化了马铃薯薯渣固态发酵生产菌体蛋白饲料的发酵工艺,初步确定了薯渣固态发酵的适宜条件,即采用自然pH值,物料质量比(薯渣:麸皮)为90:10(w/w),发酵温度32℃,发酵时间66h,在此条件下发酵饲料中粗蛋白含量较高.     

三七渣固态发酵生产灵芝菌质的工艺优化

研究了三七渣固态发酵生产灵芝菌质的工艺条件。在单因素实验的基础上,以接种量、发酵温度、发酵时间为影响因子,生物量为响应值,采用响应面分析法优化发酵工艺条件。结果表明,接种量、发酵时间对发酵结果的影响极显著(P<0.01),发酵温度对发酵结果的影响显著(P<0.05),接种量和发酵时间、发酵温度和发酵时间之间的交互作用极显著(P<0.01);优化的发酵工艺条件为:接种量15.2%,发酵温度28.4℃,发酵时间14 d,在此条件下,每克灵芝菌质中生物量的预测值和验证实验值分别为0.4327和0.4205 g,二者相对误差为2.82%。固态发酵三七渣生产灵芝菌质为三七渣的资源化利用提供了一条新途径,响应面分析法用于发酵工艺条件的优化准确性高、误差小。     

甜橙皮渣发酵蛋白饲料的研制

利用甜橙加工制汁后的废料———甜橙皮渣进行固态发酵制作蛋白质强化饲料。通过对发酵饲料样品的相关营养成分分析测定等方式筛选菌种、优化发酵条件,即经过单菌试验初步筛选出5株优良菌种,进行3种菌的混合固态发酵,找出适宜该皮渣发酵的优势菌种组合,并对发酵条件进行了优化设计,结果为:添加15%左右的麸皮;在温度29℃左右,pH自然下培养4~5d;混菌接种比为黑曲霉(2281)∶康宁木霉(13016)∶产朊假丝酵母(1807)=1∶2∶3。该饲料样品的粗蛋白含量比相应对照高出近80%,是纯皮渣对照样粗蛋白(绝干含量)的3~4倍。此强化蛋白饲料未添加任何无机物或有机氮,全天然,无污染。     

Fenhexamid residues in grapes and wine

The behaviour of the fungicide, fenhexamid, on grapes, and during wine-making, as well as its effect on the microflora of alcoholic and malolactic fermentation has been studied. After treatment, the residue on grapes decreased rapidly to one-third of the initial level after the first week, while it remained constant during the following two weeks. At harvest, in the wine obtained by vinification without skins, the fungicide residue decreased on average by 49% , while in the wine obtained by vinification with skins, the decrease was on average 62% . The presence of this fungicide on grapes and in the wine did not affect alcoholic and malolactic fermentation, nor did fermentation cause any degradation of the fungicide. A simple and rapid gas chromatograhic method (GC-NPD) for the determination of fenhexamid residues in grapes, must and wine is described.     

赖氨酸发酵动力学研究——兼流加方式优化

在40L中试发酵罐上用优选菌株进行了L-赖氨酸分批流加发酵,用实验数据对文献报道的分批发酵动力学模型进行了验证。结果发现所有模型都不能很好的描述赖氨酸分批发酵过程动力学。最后探讨了赖氨酸分批发酵的动力学机理,给出了流加优化方案。     

Modeling the effects of initial nitrogen content and temperature on fermentation kinetics of hard cider

Hard apple cider manufactured as a value-added product will increase consumption of excess American apples and give impetus to local industry. For larger scale productions, a mechanistic model that could predict the fermentation kinetics would be a useful tool for understanding and designing processes. Hence, the objective of this study was to apply a simple mechanistic model to predict fermentation kinetics of hard cider from Michigan apples and study the combined effect of initial nitrogen and temperature on fermentation. Kinetic parameters of the primary mechanistic model based on Monod kinetics were estimated non-linearly via the Runge-Kutta method. Four coupled ordinary differential equations were used for each of the four dependent variables, yeast cell concentration, nitrogen, sugar and ethanol concentration. For the secondary model, it was proposed to model the effect of temperature and initial nitrogen content on the kinetic parameters of the primary model with an Arrhenius relationship. The current study is the first known application of a mathematical model to the hard cider fermentation process.     

固态酒精发酵动力学研究

对固态酒精发酵过程所形成产物及总糖的规律进行了探讨，确定了在给定的温度、pH、淀粉浓度等条件下酒精浓度、细胞数及总糖的动力学方程。     

Determination of ivermectin and moxidecin residues in bovine milk and examination of the effects of these residues on acid fermentation of milk

Ivermectin (IVM) and moxidectin (MXD) are broad-spectrum antiparasitic drugs not approved for use in dairy animals, although their use in dairy sheep, goats and cattle nevertheless occurs in many parts of the world. The work reported here describes (1) the application of an HPLC method (including milk samples clean-up and chemical extraction) to quantify IVM and MXD residues in bovine milk, and (2) an assessment of the effect of different IVM and MXD concentrations on bovine milk acid fermentation. The latter was carried out using the 'yoghurt test' to determine the minimum IVM and MXD concentrations affecting milk acid fermentation. The sample clean-up, chemical extraction and the validated HPLC method allowed the quantification of IVM and MXD up to 0.1 ng ml^-1 in milk with acceptable validation coefficients. Drug recoveries from fortified milk samples ranged between 72% (CV = 9.1%) and 75% (CV = 13.3%) for MXD and IVM, respectively. Neither IVM nor MXD affected the acid fermentation of bovine milk. In fact, there was no drug-induced changes on milk acidity even at IVM and MXD concentrations as high as 1000 ng ml^-1. These results indicate that the yoghurt biological test is not suitable to evaluate the presence of milk residues for these antiparasitic compounds. Thus, a highly sensitive HPLC technique is the only reliable method for determining the presence of residual concentrations of IVM and MXD in milk and dairy products to assure consumer safety.     

Residue variability and sampling practical problems and consequences for residues monitoring

Data generated in the UK have indicated that pesticide residue levels can be highly variable between the individual fruit or vegetables from the same crop or lot in trade. Statistical experiments with these data showed that residues in composite samples, taken according to Codex recommendations, are unlikely to differ by more than a factor of 3-4 from the mean level in the lot. This was corroborated by results obtained from real composite samples. Many fruit or vegetables in trade are mixed after harvest to form combined lots. Analysis of composite samples provides a good indication of average residues but, where the lot has been mixed, such average values are potentially misleading. Residues monitoring is the best means available for general control of pesticide use and consumer exposure, but new strategies for sampling and analysis are required to address the combined effects of residues variability and mixing of lots.     

A sensitive enzyme immunoassay (EIA) for the determination of melengestrol acetate (MGA) in adipose and muscle tissues

The development of a sensitive screening method of MGA residues in bovine perirenal fat and muscle based on a competitive microtitration plate enzyme immunoassay is described. The samples were extracted with petroleum ether and purified with octadecyl-silica-cartridges. The detection limit for fat was 0.4ng/g and for muscle tissue 0.05ng/g, much lower than required for reliable detection of positive samples. The mean recovery rates of fortified samples amount to 75%, the mean intraassay variations to 7% and the interassay variation to 13%. Determination limits were validated for fat at 2ng/g and for muscle at 0.1ng/g. The efficiency of the new screening method was successfully demonstrated by the direct comparison to GC-MS and LC-MS methods performed at natural positive samples originating from an animal experiment in which the labelled dose (0.5mg per animal and day) with and without a 48h withdrawal period or 3-fold or 10-fold the amount of MGA, respectively, was fed to Holstein Frisian heifers. In conclusion, this new screening method can be used for sensitive determination of MGA residues in adipose tissues even after low treatment doses or longer withdrawal periods.     

食品中残留农药检测技术的新进展

对食品中残留农药检测技术其新进展进行了综述。样品前处理中,固相萃取、超临界流体萃取、基质固相分散萃取得到了迅速发展和广泛应用。毛细管气相色谱、超临界流体色谱、液相色谱---质谱联用技术、酶免疫分析等已开始应用于食品的残留家药检测中。直接光谱技术和生物传感器的应用潜力很大。对食品中残留农药检测技术的发展进行了展望。     

茶叶中杀螟丹残留的气相色谱分析方法研究

介绍了一种快速、灵敏、可靠的适用于茶叶样品中杀螟丹残留量的气相色谱分析方法。茶叶样品经过稀盐酸溶液提取,在碱性条件下提取液中的杀螟丹水解反应生成沙蚕毒素,经过乙醚萃取,液-液分配净化,用毛细管气相色谱法(FPD-S)测定沙蚕毒素的残留量。结果表明:样品添加回收率在76%～103%之间,检测结果为相对标准偏差均小于10%,方法的检测限为0.01mg/kg,符合农药残留分析的要求。该方法的可行性为茶叶中杀螟丹的残留分析提供了一种简便、可靠、准确的方法。