一种灭菌新装置的设计及初步试验

阐述了欧姆加热杀菌控制系统设计方案,并利用该系统对物料使用欧姆加热技术灭菌进行了试验研究。结果表明,该控制系统满足试验要求,可以实现恒压、恒温、定时控制等功能,电压波形较理想;欧姆加热方法对大肠杆菌具有明显的杀死作用。并得出了处理电压、保温时间、处理频率对大肠杆菌残菌率的影响规律。     

微波技术对鲜榨西瓜汁杀菌效果的影响分析

为探明微波技术对鲜榨西瓜汁的杀菌效果和影响因素,首先以旱砂西瓜汁为研究对象进行不同微波功率、微波处理时间和样品初始温度3个因素下的杀菌试验验证分析.其次通过响应曲面分析法研究以上3个因素对西瓜汁理化指标和感官评定的影响程度,得出微波功率、微波处理时间和样品初始温度的最优解.单因素试验结果显示:初始温度为30℃和微波处理...     

Reproductive performance and mature gonad morphology of triploid and diploid Black Tiger shrimp (Penaeus monodon) siblings

Sibling harvest age Black Tiger shrimp triploids and diploids of both sexes were reared to reproductive maturity, crossed with wild caught females and males, conditioned for spawning and a comprehensive reproductive performance trial was undertaken. Ovarian development, spawning frequency, fecundity, hatch rate, gonad morphology, male reproductive tracts and thelycum impregnation rates of the wild female × triploid male cross were assessed. After ablation, ovarian development and cycling between wild G₀ diploid and G₁ diploids was not significantly different, whereas G₁ triploids failed to show any signs of ovarian development and cycling, thus resulting in no G₁ triploid female spawnings. There were 10 G₀ diploid female × G₀ diploid male first‐spawnings and 9 G₀ diploid female × G₁ diploid male first‐spawnings, all of which produced viable nauplii. In comparison, there were 7 G₀ diploid female × G₁ triploid male first‐spawnings, none of which produced viable nauplii. The 26 wild G₀ diploid female spawnings had more eggs than the 1 G₁ diploid female spawning. Gonad morphology and male reproductive tract assessments showed impaired reproductive development in triploid gonadal tissues of both sexes (compared with sibling diploids and wild shrimp) to a point where complete maturation had not occurred. The thelycum of 16 wild G₀ diploid females crossed with G₁ triploid males had no visible spermatophore present, suggesting that G₁ triploid males are incapable of developing viable spermatophores and mating with females. This study demonstrates that the triploid females and males are incapable of producing viable gametes and are thus reproductively sterile.     

直接式杀菌在降膜式蒸发器中的设计及应用

在奶粉生产中,直接式杀菌与间接式杀菌相比具有杀菌温度稳定且比较均匀、灭菌效果佳、不易产生结垢或结焦、清洗间隔时间较长的优点,不足之处为在杀菌过程中蒸汽直接混入料液中会使料液增湿、杀菌完毕需要将增加部分水分经过闪蒸去除从而对蒸汽质量要求较高。因此,蒸汽必须经过严格过滤或采用单独的蒸汽发生装置方可进入料液中。本文仅以华禹乳品机械制造有限公司生产的RNJM03-8000型三效降膜式蒸发器在奶粉生产中的应用为例,对该设备在奶粉生产中的直接式杀菌设计过程及注意事项进行阐述。     

A new sterilization and inoculation method in silage research

The study aimed at evaluating an effective sterilization–inoculation technique to facilitate silage research on the effect of forage microflora on fermentation variables. The sterilization effect of heating at 60°C for 3 h + 103°C for 15 h was tested on samples of grass, grass–clover, white clover and maize, pre‐dried at 60°C to a dry‐matter (DM) content >900 g kg^?1. The ensilability of treated samples, reconstituted to original DM concentration (250–390 g kg^?1), was assessed by inoculation with microfloras extracted from the original samples. Microfloral inoculants were obtained by a combination of centrifugation (15 500  g for 40 min) and filtration (0·45 and 0·22 μm pore sizes) of the supernatant. The sterilization treatment effectively sterilized the forage samples but decreased water soluble carbohydrates by 49% and N buffer solubility by 22% and increased the acid detergent insoluble N proportion of total N by 53% (P < 0·05). The reconstituted silages had 18% less lactic acid, 20% less ethanol and 37% less ammonia‐N (P < 0·05), but volatile fatty acids and 2,3‐butanediol did not differ from the untreated silages (P > 0·05). Counts of lactic acid bacteria, enterobacteria, clostridia, yeasts and moulds in the two silage treatments were also similar (P > 0·05). It is concluded that, despite causing chemical and physical alterations, the sterilization–inoculation technique evaluated could be a useful tool for future studies on the effects of microflora on ensiling results.     

香蕉枯萎病田间发病株的高效灭菌方法筛选

为筛选有效防控香蕉枯萎病菌扩散蔓延的灭菌方法,采用含毒介质培养法测定咪鲜胺和多菌灵不同配比对枯萎病菌的毒力作用以筛选最佳混配液,比较最佳混配液与生石灰、草甘膦、咪鲜胺的平板抑菌和大田灭菌效果,并研究了大田不同施用方式对最佳混配液灭菌效果的影响。结果表明,咪鲜胺与多菌灵体积比为10∶1时得最佳混配液,可显著提高对香蕉枯萎病菌的抑制效果,增效系数为1.53,EC50值最小,为0.025 mg/L;4种药剂的EC50值由大到小为草甘膦生石灰咪鲜胺最佳混配液。1 000 mg/L最佳混配液喷施于大田病株5 d后根际土壤病菌含量下降了95.93%,10 d后球茎病菌含量减少了71.88%,综合灭菌效果显著优于其它处理。此外,应用打孔灌药法可显著提高最佳混配液对大田病株的灭菌效果,施用5 d后球茎病菌含量减少了95.95%。表明以打孔灌药法施用1 000 mg/L最佳混配液灭菌效果显著且操作便捷,易于推广应用。     

亚硫酸氢钠对高温灭菌再制干酪色泽的影响

解决再制干酪高温灭菌过程中的褐变.以亮度L*值、红度a*值、黄度b*值及色差△E为评定指标,考察了不同添加量的亚硫酸氢钠(NaHSO3)对高温灭菌再制干酪色泽变化的影响.结果表明:添加0.2～0.8 g/kg NaHSO3对再制干酪高温灭菌过程中防褐变效果良好.     

桃叶卫矛组织培养的研究

以桃叶卫矛的成熟胚为外植体,研究了不同消毒方法对桃叶卫矛离体胚萌发的影响,并筛选出最佳消毒液及消毒时间。同时,选取不同培养基和激素浓度进行卫矛的离体胚培养最佳激素组合筛选。结果表明:不同的灭菌剂和不同的灭菌时间对无菌苗的萌发与生长有显著的影响;筛选出MS1/2+BA0.5mg/L+NAA0.2mg/L+蔗糖30g/L+琼脂7g/L的培养基为成熟胚萌发的最适培养基配比。     

Effects of temperature and hydrogen peroxide on mycelial growth of eight Pleurotus strains

Effective use of hydrogen peroxide as a chemical sterilant in mushroom production and selection of cultivable mushroom strains for tropical conditions require knowledge of the genetic diversity in the tolerance of the strains to hydrogen peroxide and to high temperatures. Therefore, three experiments were conducted to examine the sensitivity of Pleurotus mycelium to temperature and hydrogen peroxide. In Experiment 1, eight Pleurotus strains, which included two Pleurotus sajor-caju strains, three Pleurotus ostreatus strains, Pleurotus salmoneo stramineus, Pleurotus cornicopae and Pleurotus eryngii were cultured aseptically on agar at 25, 30 and or 35 °C. In Experiment 2, the eight strains were cultured aseptically on agar at six hydrogen peroxide concentrations (0–0.1%, v/v) at 27 °C. In Experiment 3, P. sajor-caju strain 1, a fast growing strain, was cultured non-asceptically at six hydrogen peroxide concentrations (0–0.1%, v/v) at 27 °C. In Experiment 1, mycelial growth was maximal at 25–30 °C, whereas a temperature of 35 °C was detrimental to mycelial growth except in one strain. At the highest temperature tested (35 °C), the relative mycelial growth rate (% of maximum) ranged from 6 to 91%, indicating marked differences in tolerance of the strains to high temperature. In Experiment 2, the mycelial growth rate in all strains increased when hydrogen peroxide was increased from 0 to 0.001% (v/v), and then decreased with further increments in hydrogen peroxide concentration. The strains differed markedly in sensitivity to hydrogen peroxide. The hydrogen peroxide concentration associated with 50% reduction in maximum mycelial growth rate due to toxicity (EC₅₀) ranged from 0.009 to 0.045% (v/v). It was noted that P. sajor-caju strain 1 which was the most tolerant strain to high temperature was also the most tolerant to high hydrogen peroxide concentration. In Experiment 3, involving non-aseptic culture of P. sajor-caju strain 1, bacterial growth was observed at concentrations ≤0.016%, whilst the upper hydrogen peroxide concentration limit for fungal growth was 0.025% (v/v). The highest hydrogen peroxide concentrations 0.016% (v/v) and 0.025% (v/v) in which bacteria and fungi, respectively, were observed to grow were within the concentration range 0.009–0.028% (v/v) that was found in Experiment 2 to cause a 50% reduction in mycelia growth in six of the eight Pleurotus strains tested. Use of hydrogen peroxide as a chemical sterilant in conjunction with strains highly tolerant of its toxicity offers a very cheap method of producing spawn as well as the mushrooms, and opens up opportunities for poor rural people.     

几种消毒药剂对蚕蛹羽化的影响试验

为了筛选蚕种生产上实用有效的蚕蛹消毒剂,用有效氯质量分数为0.3%、0.5%的漂白粉液对蛹体消毒,结果使蚕蛹的羽化率降低1.2%～7.8%,且消毒液中的有效氯含量越高,对蛹体的刺激越大,对蚕蛹羽化的影响也越大;用402防僵液对蛹体消毒后蚕蛹羽化率明显降低,因该药剂只对家蚕真菌病具有防治效果,而对细菌类败血病的防治效果差,所以不宜用于蛹体消毒;用有效氯质量分数为0.3%的蚕用消毒剂消特灵主剂溶液进行蛹体消毒,不仅能有效杀灭病原菌,而且对蛹体的刺激小,有利于蚕蛹羽化,适宜用于蛹体消毒。