CINNAMIC ACID AS THE BASIS OF A MEDIUM FOR THE DETECTION OF WILD YEASTS

Cinnamic acid (100 μg ml^?1) incorporated in a solid medium was found to inhibit the growth of brewing strains (Pof^?) of yeast while permitting the growth of Pof+ wild yeast contaminants. Typically, colonies of Saccharomyces cerevisiae var. diastaticus (Pof+) mixed with brewing yeast (S. cerevisiae NCYC 240) were visible after 5d incubation at 25°C. The incubation time required to detect a selection of brewery wild yeast isolates was found to vary from 3–12 d.     

DETECTION OF WILD YEASTS IN THE BREWERY

The potential of an established culture medium, Wallerstein Laboratories' nutrient agar, for the detection of wild yeasts has been evaluated and recommended for microbiological quality control in brewery laboratories. Wild yeast strains, including Saccharomyces species, can be differentiated from strains of Saccharomyces cerevisiae by the colour, form and rate of growth of their colonies on this medium within 2–3 days. The sensitivity of the method is such that one wild yeast can be detected in a Saccharomyces cerevisiae population of the order of 10° cells.     

GROWTH OF AEROBIC WILD YEASTS

Wild yeasts of the genera Debaryomyces, Hansenula and Pichia are commonly considered to be associated with spoilage only under aerobic conditions. However, in pure cultures in either wort or a synthetic medium of yeast nitrogen base + 10% glucose, yeasts of these genera grew as well as a brewing strain of Saccharomyces cerevisiae under anaerobic conditions. Growth of S. cerevisiae was increased by the addition of unsaturated fatty acid (Tween 80) or ergosterol to the medium for anaerobic culture. No equivalent requirement was observed for the wild yeasts examined. Indeed, growth of the wild yeasts was often reduced by the addition of Tween 80, which as a surfactant prevented formation of the surface film of growth. Even under anaerobic conditions, these yeasts grew best with a surface pellicle. Although capable of good anaerobic growth in pure culture, growth of the wild yeasts was suppressed under anaerobic conditions in mixed culture with S. cerevisiae, simulating a contaminated brewery fermentation. However, the contaminants competed successfully with S. cerevisiae under aerobic conditions. There was no evidence of a “killer” effect, but prevention of pellicle formation, or production of inhibitory levels of pH or ethanol under anaerobic conditions could explain the suppression of wild yeasts under anaerobic fermentation conditions.     

DETECTION OF WILD YEASTS IN THE BREWERY EFFICIENCY OF DIFFERENTIAL MEDIA

The efficiency of five differential media in the detection of wild yeasts was compared. On the basis of the types of wild yeast they are able to detect, these differential media were classified into two groups. Group I consists of actidione medium and lysine medium, and is suitable for the detection of non-Saccharomyces wild yeasts. In this group, the lysine medium detected more species and a higher percentage of wild yeasts than the actidione medium. Group II consists of crystal violet medium, SDM, and Lin's medium, and is suitable for the detection of Saccharomyces wild yeasts. In this group, Lin's medium is superior to crystal violet medium and SDM for wild yeast detection. It is suggested that lysine medium and Lin's medium be employed together for the detection of wild yeasts in the brewery.     

PRACTICAL EXPERIENCE WITH RAPID METHODS OF DETECTING YEASTS IN BREWERIES

The routine use of rapid methods of detecting yeasts in brewing control laboratories is discussed. A modified microcolony procedure exploiting epifluorescence is used to monitor packaging of sterile beer. Saccharomyces diastaticus, which is a potentially serious contaminant during aseptic bottling of lager can be recovered selectively by incubation at 37°C. Neither method is specific for a single species and further rapid identification can be carried out using the API carbohydrate diagnostic system.     

FORMULATION AND TESTING OF CUPRIC SULPHATE MEDIUM FOR WILD YEAST DETECTION

A new differential medium, cupric sulphate medium, used for the detection of wild yeasts has been formulated and tested. This medium suppressed the growth of culture yeasts and supported that of most non-Saccharomyces wild yeasts. It is not suitable for the detection of Saccharomyces wild yeasts. The contaminating wild yeasts in yeast samples and swab samples were easily detected by this medium. Since Lin's medium or modified Lin's medium is suitable for the detection of Saccharomyces wild yeasts, it is suggested that they be used in conjunction with cupric sulphate medium for detecting a more complete spectrum of wild yeasts.     

山杏仁蕨菜罐头的工艺技术研究

山杏仁和蕨菜具有较高的营养价值和保健功能，由于二者均为野生植物，无污染，是天然绿色食品，利用野生资源生产罐装山杏仁和蕨菜，食用安全、方便、卫生，市场前景广阔。本文对山杏仁蕨菜罐头加工工艺和技术要点进行了研究和探讨。     

THE SPORULATION AND MATING OF BREWING YEASTS

A study has been made of the sporulating behaviour of twenty selected brewing strains of yeast, and the mating activity of the products of sporulation. ‘Lager’ yeasts (strains of Saccharomyces carlsbergensis) in general sporulated to a lesser degree and more slowly than ‘ale’ yeasts (strains of Saccharomyces cerevisiae) and produced 1-or 2- spored asci compared with 2-or 3- spored asci for the latter yeasts. Most of the parent strains of S. cerevisiae were shown to be heterozygous for mating type, and they were all probably either triploid or aneuploid. Two of the strains of S. carlsbergensis were apparently homozygous for mating type and also triploid or aneuploid. The compatibility system favours outbreeding of yeasts, ‘ale’ yeasts being more compatible with ‘lager’ yeasts than with other ‘ale’ yeasts.     

MYGP + COPPER,A MEDIUM THAT DETECTS BOTH SACCHAROMYCES AND NON-SACCHAROMYCES WILD YEAST IN THE PRESENCE OF CULTURE YEAST*

Lin's copper sulphate medium for the detection of non-Saccharomyces wild yeast was modified, mainly by reducing the concentration of copper sulphate, with the aim of producing a medium that could detect a wide range of both non-Saccharomyces and Saccharomyces wild yeast. The performance of the resultant MYGP + Cu medium was compared to that of crystal violet and lysine media using pure cultures of wild yeast, pitching yeast and brewery samples. The growth of the pitching yeasts examined was suppressed more in MYGP + Cu than in crystal violet and the 4 ale yeasts were more susceptible to copper inhibition than the 3 lager yeasts. Neither MYGP + Cu nor crystal violet could detect all the wild Saccharomyces species tested but the proportion detected by each was similar. Twenty-seven out of 28 non-Saccharomyces wild yeasts tested could be detected in MYGP + Cu. When brewery samples were examined, the detection rate by MYGP + Cu compared favourably with that by a combination of crystal violet and lysine. MYGP + Cu is particularly suited to the monitoring of the production of cask-conditioned ales.     

RAPID METHODS FOR THE DETECTION OF YEAST AND LACTOBACILLUS BY ATP BIOLUMINESCENCE

Present plating methods for the detection of potential spoilage organisms in packaged beers require 2–3 days for yeast, and 5–7 days for lactic acid bacteria. Simple and inexpensive sterility tests based on bioluminescence have been developed for the detection in broth media of small numbers of yeasts in 1 day, and lactic acid bacteria, in both normal and heat-stressed conditions, in 3 days.     

反相高效液相色谱法测定酵母RNA降解的5''''-核苷酸

建立了一种利用反相高效液相色谱法同时测定啤酒废酵母提取的核糖核酸（RNA）降解生成的4种核苷酸（5’-AMP、5’-CMP、5’-GMP、5＇-UMP）的方法，应用反相μBondapak C18柱，水：甲醇：冰醋酸：四丁基氢氧化铵（TBAOH，10％）=883．5：100：15：1．5，检测波长254nm，4种核苷酸能一次性分离，回收率均达到96％以上，标准偏差分别为2．74％、0．98％、1．65％和1．23％。     

五种常见野菜Vc含量的测定

The contents of vitamin C of the wild vegetables in the Capsella dursa-pastoris,Portulaca oleracea,Talinm paniculatum,Stellaria aquatica and Sonchus arvensis were determined. The result indicates that the contents of vitamin C of the wild vegetables are very high. Some proposals on the utilization of wild vegetables put forward.     

THE INSTITUTE OF BREWING ANALYSIS COMMITTEE

The serological technique described by Richards & Cowland (Journal of the Institute of Brewing, 1967, 73, 552) has been studied by the Microbiology Sub-Committee of the Analysis Committee. The adoption of this method is recommended and detailed instructions are given for carrying out the recommended procedure.     

野果胡颓子的开发利用

本文报道了粤东地区野生胡颓子植物资源的调查结果,分析了胡颓子的营养价值和保健功能,并提出了开发利用的建议.     

山野菜(鸭儿芹)软包装的护绿工艺研究

以山野菜（鸭儿芹）为原料，经护色、调味、杀菌、包装等工艺制成色泽好、营养丰富、口感好的并具有特殊风味的成品。通过EDTA、Na2CO3、CaCl2的护绿单因子实验与铜锌联合护色的正交实验，测定吸光度值后分析得出联合护色的最佳工艺参数。     

BIOTIN-ACTIVE COMPOUNDS,THEIR EXISTENCE IN NATURE AND THE BIOTIN REQUIREMENTS OF YEASTS

After a short account of the discovery of biotin and the progress of early biotin research, the natural occurrence of biotin with particular consideration to the raw materials used in the fermentation industry and its products is described. Of the many known biotin derivatives, those appearing in nature and those which can be converted to biotin-active (or inactive) compounds by simple procedures are reported. Ways to by-pass the need for biotin in microbes is discussed. The importance of biotin in yeast production, the biotin requirements of yeast, and the effect of culture conditions on these requirements are reported. The close relationship between the participation of biotinylenzymes and the biotin requirements is noted.     

粤东地区野生蔷薇科果树资源研究

报道了粤东地区野生蔷薇科植物资源的调查结果，记录到该地区野生蔷薇科植物资源有9属、38种（含变种），分析了部分野生可食悬钩子的营养价值和保健功能，并提出了开发利用的建议。     

涤纶牵伸网络丝生产技术新探

丝在冷盘上绕第三圈时经过网络喷嘴,最后在冷盘上绕第四圈,使高频气流对丝产生的弦振动不影响卷绕成型,使钢领板换向造成的张力波动不影响网络成型,提高了网络均匀度和满卷率,消除了松圈丝。     

COMPARISON OF METHODS FOR THE DETERMINATION OF CELL VIABILITY IN STORED BAKER'S YEAST

The classical plate method for discriminating between viable and nonviable yeast cells in stored baker's yeast was compared with dead cell staining techniques using methylene blue and three fluorochrome stains. The increase of dead yeast cells during storage of baker's yeast for up to 16 days at 5°C, 20°C and 35°C was determined. During prolonged storage, especially at 35°C, the death rate increased rapidly and the yeast cake began to soften because of autolysis. In these conditions the choice of method for determining the proportion of dead cells proved to be of great importance. Useful results for yeast stored for some time at 35°C could be obtained only by the fluorochrome technique using primuline, acridine orange or acriflavine as fluorochromes.