A RAPID SMALL SCALE METHOD FOR THE DETERMINATION OF MALT EXTRACT

A rapid, small-scale method was developed using 1 g of ground malt mashed in 10 ml of water at 65°C. The extract was centrifuged and the specific gravity determined using a density meter. The method was compared with an earlier small-scale method and the Institute of Brewing method and was found to have good precision (CV 1.2%). Absolute malt extract values were not significantly different (P = 0.05) from those obtained by the IOB method.     

A SIMPLE,RAPID METHOD FOR THE DETECTION OF SUBSPECIES OF ZYMOMONAS MOBILIS

Zymomonas strains are simply and rapidly detected after growth in a selective liquid medium by the addition of a Schiff's reagent. This dye reacts with acetaldehyde produced by Zymomonas to give a deep purple colour. The optimal conditions for the test are evaluated and it is shown to be specific for Zymomonas strains. The use of the dye reaction in routine microbiological quality control is described. A comparison is presented of the dye test and the use of an agar medium containing sulphite and lead acetate on which Zymomonas strains which produce H₂S form characteristic colonies.     

RECENT ADVANCES IN THE RAPID DETECTION OF BREWERY MICRO-ORGANISMS AND DEVELOPMENT OF A MICROCOLONY METHOD

Recent developments in the rapid detection of low concentrations of micro-organisms are reviewed. A modification of the microcolony method, involving uptake of optical brighteners by developing yeast colonies, is described. The method includes the use of incident light microscopy and appears to offer advantages over other detection methods.     

THE RAPID DETECTION OF BREWERY CONTAMINANTS BELONGING TO THE GENUS SACCHAROMYCES BY A SEROLOGICAL TECHNIQUE

The cells of contaminant Saccharomyces spp. are rendered fluorescent by means of fluorescein chemically bound to antibody protein. The fluorescent contaminants are observed microscopically, and an estimate of levels of contamination likely to be encountered in the brewery can be obtained within 3 hr. A serum of suitable specificity is obtained by careful cross-absorption with a brewing yeast, and by combining two sera, all brewery contaminants of the genus Saccharomyces so far encountered are detected. Careful selection of the brewing strain used for cross-absorption, and control of the cross-absorption procedure itself, allows the recognition of certain wild-type Sacch. cerevisiae strains.     

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.     

SENSITIVE AND RAPID DETECTION OF ENTEROBACTER SAKAZAKII IN INFANT FORMULA BY LOOP-MEDIATED ISOTHERMAL AMPLIFICATION METHOD

Enterobacter sakazakii is an emergent pathogen associated with ingestion of infant formula milk and was defined in category "A" of the hazard identification by FAO and WHO on microorganisms, which is based on the strength of evidence of a causal association between their presence in powdered infant formula and illness in infants. In this study, a loop-mediated isothermal amplification (LAMP) method has been developed for the detection of E. sakazakii in infant formula. The assay detected the species-specific DNA sequence of the 16S-23S rRNA internal transcribed spacer. The sensitivity of the detection is 1.2 cfu per 100 g infant formula with the selective enrichment. As the amplification is made under isothermal conditions, only a water bath or heating block is needed to maintain the required temperature. Thus, the method will be easily generalized and popularized in the future.

PRACTICAL APPLICATIONS

Enterobacter sakazakii is an emerging opportunistic pathogen associated with meningitis, bacteria and necrotizing enterocolitis in neonates. Powdered infant formulae have been implicated as the source of infection in neonatal meningitis. Thus, in order to minimize the hazard caused by E. sakazakii , it is of utmost importance to develop a rapid, sensitive and simple method for the early detection of this bacterium in infant formula.
In our study, the E. sakazakii was detected sensitively and rapidly in the infant formula by the loop-mediated isothermal amplification (LAMP) assay. LAMP is easy to perform once the appropriate primers are prepared. The LAMP method will be a simple and rapid method for the scene detection of E. sakazakii as only four primers, a Bst polymerase and a regular laboratory bath are needed.     

THE RAPID DETECTION OF BREWERY SPOILAGE MICRO-ORGANISMS

Recent developments in the rapid detection of low concentrations of micro-organisms are discussed and their relevance to improved brewery quality control methods is assessed. A method based on the change in pH of a general purpose growth medium appears to offer the advantages of both time and sensitivity over methods currently in use.     

EVALUATION OF FLUORESCENT IN SITU HYBRIDIZATION (FISH) AS A RAPID SCREENING METHOD FOR DETECTION OF SALMONELLA IN TONSILS OF SLAUGHTERED PIGS FOR CONSUMPTION: A COMPARISON WITH CONVENTIONAL CULTURE METHOD

The pork tonsils are an important carrier of Salmonella, which could be involved in the contamination of pork products during the slaughter process. This paper reports a 23S rRNA fluorescent in situ hybridization (FISH) method used as a rapid screening tool for Salmonella detection in tonsils of slaughtered pigs and its comparison with the conventional culture method. As a rapid screening method, the FISH technique would reduce the high volume of negative samples that are routinely analyzed, indicating presumptive positive samples in a real and practical time. The use of a Sal3 probe allowed the rapid (7 h) Salmonella detection in 16 (34%) of 47 naturally contaminated tonsils, without pre‐enrichment. Salmonella was isolated by the culture method in six samples that were also FISH‐positive samples, and FISH failed to identify only one of the culture‐positive samples. The results indicate the potential of this technique as a rapid screening method for detecting Salmonella in tonsils from pork slaughtered for consumption.     

A RAPID METHOD FOR THE DETERMINATION OF DIASTATIC POWER

A rapid method for the determination of diastatic power is described. The enzyme extraction and starch hydrolysis steps have been shortened to 10 min each and a colorimetric method involving the use of p-hydroxybenzoic acid hydrazide has been used for the determination of reducing sugars. The method avoids some sources of error associated with previous methods. The sensitivity of the method allows the use of small samples making it suitable for the measurement of diastatic power in barley breeding.     

酶法制取葡萄糖的工艺技术

采用酶法水解与目前先进的过滤、离子交换及蒸发浓缩等下游工程技术结合，研究葡萄糖加工的工艺条件与提高产品纯度和得率的实用技术。通过实验确定最佳工艺条件为：液化时，pH6.0-6.5，温度85℃，时间40min，α-淀粉酶用量0.3％，淀粉浆浓度30％；糖化时，pH4.2～4．5，温度60℃，时间48h，糖化酶用量0.6％。     

RAPID METHOD FOR DETECTION OF SALMONELLAE ATTACHED TO CHICKEN SKIN1

A rapid, sensitive nitrocellulose membrane lifting technique was developed to identify Salmonella typhimurium attached to chicken skin. Basically, this method used a nitrocellulose membrane to remove salmonellae attached to chicken skin. The membrane with attached salmonellae was then incubated on xylose lysine deoxycholate (XLD) agar for 18 h at 37°C. Appearance of black colonies on the white membrane was considered a positive presumptive test for salmonellae. Immunostaining of colonies on the nitrocellulose membrane was then used to confirm presence or absence of salmonellae. This technique can be used to identify salmonellae contamination of chicken skin in less than 24 h and was shown to be more sensitive than presently used swabbing or washing techniques.     

A RAPID METHOD FOR ESTIMATING THE VISCOSITY OF BARLEY EXTRACTS

A simple technique for determining the viscosity of extracts of small samples of barley grains is required for use in screening large numbers of selections in a breeding programme. Extraction of 2-g samples of ground grain at pH 1.5 has proved satisfactory and the results of viscosity measurements of such extracts are compared with published information on β-glucan contents and with maltsters' assessments of a number of barley varieties.     

食品微生物快速检测技术研究进展

随着食品工业的迅速发展,建立食品微生物快速检测方法,对食品生产、运输、销售过程中质量的监控具有十分重要的意义.综述了目前较为先进的微生物快速检测技术的原理和应用,主要有免疫学技术、代谢学技术和分子生物学技术.