Polyphosphates as inhibitors of surface mould growth on hard cheese during ripening

A novel treatment using polyphosphates to protect cheeses against superficial mould growth was assayed. The treatments were: control commercial paint with natamycin (I), commercial paint based on polyvinyl–water (II), immersion in a saturated solution of polyphosphate (III), immersion and commercial paint (IV), commercial paint of polyphosphate solutions (V) and immersion and commercial paint of a saturated solution of polyphosphates (VI). The cheeses were ripened for 6 months. Superficial mould growth was inhibited in groups IV and VI when compared to cheeses from the control group (I). Statistical sensory analysis made between cheeses from groups IV and I (control) showed no significant differences.     

Determination of the Relative Ploidy in Different Saccharomyces cerevisiae Strains used for Fermentation and ‘Flor’ Film Ageing of Dry Sherry-type Wines

The full chromosomal karyotype of six enological Saccharomyces cerevisiae strains used for fermentation and biological ageing of sherry-type wines was studied. A genetic method based on the analysis of segregation frequencies of auxotrophic markers, among random spore progeny of hybrids, constructed between laboratory and industrial wine strains (Bakalinsky and Snow, 1990) was used. This method was combined with the analysis of strains by pulsed-field gel electrophoresis. The results obtained clearly indicate the presence of two, three or four copies of a chromosome in the industrial strains examined, and thus confirm that aneuploidy/polyploidy is not uncommon in these strains. In all strains examined, chromosome XIII polysomy is observed. This chromosome contains the ADH2 and ADH3 loci, that code for the ADHII and ADHIII isoenzymes of alcohol dehydrogenase, which are involved in ethanol oxidative utilization during biological ageing of wines. Tetrad analysis for the ‘flor formation’ character suggests two possibilities: this character is either regulated by at least a digenic system, or by only one gene present on a chromosome which is, at least, disomic.© 1997 John Wiley & Sons, Ltd.     

不断发展的数据中心——专题报告：新趋势影响数据中心网络架构

企业制订业务目标来控制运营成本并提高业务灵活性,而数据中心使用的高新技术为满足这些业务目标提供了新方式。部署高新技术将帮助企业数据中心实现快速发展。     

BASIC CONCEPTS IN RISK ANALYSIS AND THE DECISION-MAKING PROCESS

This paper presents a discussion on the basic concepts behind engineering safety and proposes a general framework, which considers risk analysis as a fundamental tool for the decision-making process in engineering. A discussion on the nature of damage and a characterisation of failures, accidents and disasters is presented. Then, a brief discussion on the existing failure modelling alternatives and requirements is given followed by a critical review on existing definitions of concepts such as hazard, vulnerability and risk. New strategies for understanding, modelling and carrying out hazard, vulnerability and risk assessments are proposed. Finally a general framework for the decision making process based on risk analysis is presented.     

Use of reconstituted concentrated nonfat milk for the production of UHT milk: physical and chemical effects and stability

The objective of this work was to evaluate the use of reconstituted concentrated nonfat milk for the production of UHT milk and to evaluate its physical and chemical effects and stability. The study considered three treatments related to the raw material and processing parameters. Increasing the intensity of thermal treatments resulted in increased hydroxymethylfurfural (HMF) content as well as the denaturation of whey protein. During storage, the milk that was produced from reconstituted concentrate displayed a lesser degree of proteolysis and higher pH value, sedimentation index and HMF, compared to natural milk. Under higher storage temperatures, the degree of proteolysis, HMF and pH decreased and the sedimentation index increased.     

EFFECTIVE PURIFICATION PROCEDURE OF ASPERGILLUS ORYZAEα-AMYLASE FROM SOLID STATE FERMENTATION CULTURES INCLUDING CONCANAVALIN A-SEPHAROSE

Solid state fermentation cultures of Aspergillus oryzae NRRL 3485 on moistened wheat bran produced high levels of α-amylase as judged by the specific activity of water extracts (500–700 units/mg protein) and by the enzyme concentration (around 0.15 g/L) in those extracts. The purification of α-amylase by affinity chromatography on Concanavalin A-Sepharose is described. A first DEAE-Sepharose chromatography step (binding of the enzyme contained in the water extract and further elution with 0.2 M NaCl, pH 5) was necessary in order to remove contaminants that hinder the binding of the glycoprotein α-amylase to the lectin. Elution was performed with 7.5 mM α-D-methylmannoside. The enzyme was obtained highly concentrated and purified with a specific activity of 2000 units/mg protein and a recovery of around 60%, free of α-glucosidase, amyloglucosidase and color contaminants. The purity of the enzyme preparation was assessed through nondenaturing gel electrophoresis and sucrose gradient centrifugation. An improvement of the performance of the purification procedure is presented in which the maximum capacities of both the anion exchanger and the lectin matrices were exploited.     

Extrusion Cooking Reduces Recoverability of Fumonisin B1 from Extruded Corn Grits

A split-split plot design was used to determine the effects of extrusion cooking on the recoverability of the mycotoxin Fumonisin B₁ (FB₁). Unextruded and extruded samples of spiked corn grits were analyzed for FB₁ by two methods, commercial enzyme linked immunosorbant assay (ELISA) and HPLC. Extrusion cooking resulted in more apparent loss of FB₁ with mixing screws than nonmixing screws. Losses of recoverable FB1 (p≤0.05) were observed at 120°C and 160°C with the mixing screws. A linear increase in loss of recoverable FB₁ was observed (with the nonmixing screws) as the moisture content increased.