ANTIMICROBIAL ACTIVITY OF SOME FOOD FLAVORING COMPOUNDS

Of 21 food flavoring compounds tested against 39–40 organisms, 10 were ineffective at 1,000 ppm or 10 mM either at pH 6 or 8 and by either surface plating or in broth. The 11 effective compounds were d- and l-carvone, diacetyl, ethyl vanillin, eugenol, maltol, menthol, phenylacetic acid, phenylacetal-dehyde, 2,3-pentanedione and vanillin; with diacetyl and eugenol being the most effective. All were more effective at pH 6 than at pH 8. With the exception of maltol and phenylacetic acid, each was generally more effective against fungi than bacteria with the lactic acid bacteria being the most resistant. At pH 5.5 and 5°C, diacetyl was inhibitory to Pseudomonas fluorescens and P. geniculata at < 10 ppm. The findings suggest that compounds used in acid foods, ostensibly as flavoring agents, may exert antimicrobial effects when considered in context with all parameters of growth.     

HEXOSAMINE PRODUCTION BY PSYCHROTROPHIC FOOD-SPOILAGE BACTERIA UNDER VARYING GROWTH CONDITIONS

Four psychrotrophic, gram negative meat isolates were grown at 6 and 22°C with and without aeration, in AOAC synthetic broth with 0.1% glucose and in a basal medium containing 0.1% glucose and 0.5% glycine (BMGG-1). In AOAC broth, three strains produced more hexosamine at 6°C, while the fourth produced more at 22°C. Three of the four strains also produced more slime at 6°C. All four strains grew faster with aeration at both temperatures, but produced less hexosamine. Under all conditions, the growth rate of each strain was inversely proportional to its hexosamine production. During the growth cycle in BMGG-1, medium pH dropped until the log phase was under way and then rose again through the stationary phase. This rise coincided with the depletion of glucose. Hexosamine production first became detectable at the end of the log phase, rose during the stationary phase, and then leveled off. Adjusting pH to prevent the initial drop increased both growth and hexosamine production. Raising the concentration of glucose to 0.5% accelerated growth but decreased hexosamine production. Approximately 95.1% of the hexosamine produced was cell-associated. It consisted primarily of glucosamine polymers with a lesser amount of galactosamine. Only 3.0% of the nitrogen from the BMGG-1 was utilized by the cells. Of this 3.0%, 58% was used for ammonia, 27.2% for hexosamine, and 14.8% for other substances. Of the 40.7% used for total cell production, 63.8% went into hexosamine.     

KINETIC ANALYLSIS OF THE FORMATION OF NITROSYLMYOGLOBIN

The formation of nitric oxide myoglobin (nitrosylmyoglobin) was followed in buffered solutions in which the concentrations of ascorbate, nitrite, chloride, myoglobin and hydrogen ion were varied systematically to determine their effect on the rate constants. The rate of formation of nitrosylmyoglobin was zero order with respect to the pigment. The orders for the other reactants were determined by plotting the zero order rate constants as functions of varying orders of each reagent to determine which order gave a linear plot. The results were used to develop a mechanism and a mathematical expression for the reaction. Two reaction sequences involving different nitrosating species were involved; 1, direct action of nitrous acid and 2, the formation of nitrosyl chloride. Both species then nitrosated ascorbate and ascorbic acid, by different mechanisms. The nitric oxide for nitrosylmyoglobin formation came from the nitrosated ascorbate.     

The Internet: a Paradigmatic Rupture in Cumulative Telecom Evolution

The paper investigates the impact the Internet may have in theevolution of telecommunications networks. First, we show whythe Internet, emerging from a different cognitive perceptionof the data communication problem, has led to a new networkarchitecture based on: (i) the distribution of the ‘networkintelligence’ to the user equipment; (ii) the very cost-effective‘statistical sharing’ of the network resources (i.e. getting the whole bandwidth of the network for short periodsof time); (iii) the establishment of an Internet Protocol (IP)‘gateway’ facilitating interoperability betweenheterogeneous infrastructure facilities—instead of theoperator—controlled homogeneity of the telecom networks;and (iv) an ‘adaptative’ way for open standards—setting.Second, we suggest that two technological trajectories (telecom—‘creative accumulation’ and Internet—‘creativedestruction’) should dynamically co-exist henceforth andcompete for market shares—possibly during later evolutionarystages generating relatively different national or even localized(e. g. local providers) trajectories of evolution (with differinginterfaces and standards). Furthermore, we explore the questionof whether the Internet’s interoperability model may bea useful policy paradigm for future information infrastructures,and we start to discuss the implications of requisite interoperabilityon the comunications industry‘s structure itself. Overall,our preliminary observations raise questions about the possibilitiesof two ‘technological trajectories’ co-existing,and the relationship between the interoperability and learningconditions in the network industries.     

An Interactive Shell for Batch Programs

Many programs have been and are currently being developed in which the input files or associated data bases must be produced independently of the main program. This article describes two programs which are used to develop an interactive, menu-driven system of input prompts which is then used to create and maintain information files for other programs. The two program system provides an easy method to develop well-structured, interactive input programs without the high development costs required to write original code. Graphics can be developed for any input screen and a command language can be specified for data output. Two examples are provided to present an overview of the system.     

LEONARDO DA VINCI'S TENSILE STRENGTH TESTS: IMPLICATIONS FOR THE DISCOVERY OF ENGINEERING MECHANICS

In one of Leonardo Da Vinci's notebooks, an experiment is described where strengths in tension are measured for various lengths of wire. The notebook indicates that the results of these experiments were that longer wires were weaker than shorter wires. This result defies classical mechanics of materials. This conflict has been explained as a note-taking failure by Leonardo. This short note develops an alternative explanation, based on the likely heterogeneity of the mechanical properties of the wire and elementary probability theory. This latter explanation has implications for the difficulty and delays experienced by early investigators into the mechanics of materials.     

EXPERT SYSTEMS FOR BUSINESS APPLICATIONS

Abstract

Expert systems are becoming more prevalent in financial and business applications. With venture capital pouring into the expert systems area, there is greater interest in expert systems by commercial firms. Companies are either building in-house expert systems capabilities or contracting out to expert system developers to construct expert systems for business applications. This paper presents much of the work being done in developing expert systems in business and discusses fertile areas for constructing more business expert systems.     

阿尔卡特最强机型--OT715

时下的新款手机层出不穷,功能也日趋完善,那么,究竟有没有所谓的终极手机呢?答案是否定的,但笔者却一直在期待能有一款手机可以在目前已技术以及成本允许的基础上,做到接近完美的程度。终于,一款笔者认为目前功能最全的手机——阿尔卡特0T715来了！ 先来看看0T715的配置吧,刚从经销商手中得到这套试用机时,笔者觉得盒子体积小,里面的东西肯定没多少。可是打开包装一看,除了标准配置的旅行充电器外,还有阿尔卡特的数据线、软件光盘,几本说明书、三包卡以及一个专用的键盘,简直是太超值了！     

Effect of Diacetyl on Foodborne Microorganisms

A set of 70 organisms consisting of 9 lactic acid bacteria, 14 non-lactic gram positives, 16 yeasts, 6 molds, 12 pseudomonads, and 13 nonpseudomonad gram negative bacteria was tested on plate count agar (PCA) at pH 5.0 to 8.0 and in the presence of varying concentrations of diacetyl. All organisms were more sensitive to diacetyl at a pH of 7.0 and below than at pH 8.0 with the greatest sensitivity at pH 5.0. The lactic acid bacteria were the most resistant while the pseudomonads were the most sensitive. Excluding the lactic acid bacteria, 300 ppm completely inhibited 95, 90, 85, and 43% respectively at pH 5.0, 6.0, 7.0, and 8.0. Using PCA at pH 6.0, three Gram negative bacteria were inhibited by 86 ppm in pour plates while 6 of 7 nonlactic cultures were inhibited by 172 ppm. The compound was shown to be effective in fresh ground beef.     

Pin Versus Disk Punch Measurements of Frankfurter Texture

Puncture measurements were made of frankfurter texture using either a pin (straight-sided shaft) or a disk (narrow shaft) punch. The forces resisting pin punch puncture were compression, tension, and friction, whereas no frictional forces were involved when the disk punch was used. Within a given set of samples, both pin and disk measurements gave the same value (avg. = 413.6 ± 1.9) for the maximum force at the yield points when extrapolated to zero penetration distance. For heterogeneous samples from a previous study, the values ranged from 34.7 to 574.9g. Negative force increments in puncture measurements are explained on the basis of deformation of the gel.