THE HEDONIC TONES OF ARTIFICIAL SWEETENERS AND THEIR MIXTURES

0s rated their liking or disliking of aqueous concentrationsof glucose, Na and Ca cyclamate, Na and Ca saccharin, and pairwisemixtures of artificial sweeteners at varying concentrations.Hedonic tones did not add arithmetically - the unpleasantnessof a mixture was often substantially more than the unpleasantnessof the components. Adequate predictions of hedonic tones ofmixtures must be made by referring back to the taste qualitiesof the mixture. This necessity for intermediate steps (i.e.,consideration of the sensory aspect) constrains considerablythe development of models which predict mixture hedonics fromthe hedonics of the mixture components evaluated separately.     

GUSTATORY REACTION TIME AND TIME INTENSITY MEASUREMENTS OF TREHALOSE AND SUCROSE SOLUTIONS AND THEIR MIXTURES

Dynamic sweetness perception of commercial food grade trehalose, sucrose solutions and their mixtures were studied for a wide range of concentrations. For gustatory reaction time (GRT), concentrations ranged from 2.3 to 13.8% for sucrose and up to 23.0% for trehalose. For time intensity (T-I) sucrose or trehalose solutions (concentration range 2.3–36.8%) and their combinations (23.0 and 36.8% total solids) were analyzed. Trehalose had bigger GRT along the studied range. Both sugars presented similar values for persistence and times of plateau and to maximum intensity, while a significant difference was observed in intensity and GRT at equal concentrations. Trehalose had longer persistence than sucrose in equi -sweet solutions. Overall sweetness profile of some sucrose solutions (i.e., 29.9% sucrose solution and 0.6 sucrose/trehalose ratio mixture at 36.8% total solids) were perceived as similar to mixtures of sucrose/trehalose or single trehalose solutions, which suggests the possibility of sugar replacement without completely modifying sweetness perception.

PRACTICAL APPLICATIONS

It has been suggested that trehalose may be a potential substitute for sucrose and other sugars used in food formulation because, although its chemical structure is very similar to that of sucrose, it is more stable at low pH and high temperatures. It is not involved in caramelization and does not participate in Maillard reaction with amino acids/proteins. In order to fully establish the potential of trehalose as a functional replacement of sucrose we have determined the sweetness dynamic profile (gustatory reaction time and time-intensity curves) of trehalose solutions and sucrose/trehalose solutions; this aspect is needed for adequately replacing (partially or totally) sucrose in food systems.     

RESOLUTION OF RACEMIC MIXTURES OF CARBOCYCLIC ANALOGUES OF NUCLEOSIDES AND ASSIGNMENT OF THEIR ABSOLUTE CONFIGURATION

Racemic trans-6-chloro-9-[2-(hydroxymethyl)cyclopentyl]purine was resolved using HPLC with a chiral column. The absolute configurations of the enantiomers were determined by NMR studies of their (R)- and (S)-methoxy-phenylacetates.     

THE EFFECT OF SOME BEVERAGES ON THE PERCEPTION OF SUCCEEDING BASIC TASTES

The objective of this study was to investigate the effect beverages have on subsequently perceived basic tastes. Two types of milk, Cola and water were used to rinse the mouth prior to conducting a Time Intensity study with basic taste solutions. From this some effects of the prior beverage onto the TI parameters was found. Especially Cola showed an effect on the intensity of the subsequently tasted sweet taste, and whole milk showed a stronger effect than skim milk. The effects showed both in size and timing of the basic taste intensities.     

THE SOLUBILITIES OF THE l-DIHALOGENATED TYROSINES IN ETHANOL-WATER MIXTURES AND CERTAIN RELATED DATA

1. The solubilities of l-tyrosine, dichloro-l-tyrosine (hydrated), dibromo-l-tyrosine (anhydrous), and diiodo-l-tyrosine in ethanol-water mixtures at 25° have been determined. 2. It was found that the solubilities of the dihalogenated substitution products of l-tyrosine are increased by addition of ethanol up to a certain concentration. Further addition of ethanol leads to a decrease in solubility. The solubility of l-tyrosine is decreased by addition of ethanol. 3. Dichloro-l-tyrosine (hydrated) was found to change to the anhydrous form when allowed to stand in the presence of ethanol. 4. The apparent heat of solution of diiodo-l-tyrosine in an ethanol-water mixture has been determined. 5. The solubility of dl-thyroxine at 30° has been determined in urea solution, ethanol, dioxan, ethylene glycol, and propylene glycol.     

COMPARISON OF TWO SIMPLE METHODS FOR THE MEASUREMENT OF DETECTION THRESHOLDS FOR BASIC, UMAMI AND METALLIC TASTES

Two simple methods were followed to determine detection thresholds for the taste of substances in aqueous solution. The methods applied were: a modification of the ascending method of limits and a method based on the use of scales. Detection thresholds were calculated for the four basic tastes (sweet, salty, acid, and bitterness), umami and metallic. Reference substances for each taste were sucrose, sodium chloride, citric acid, caffeine, monosodium glutamate and iron (II) sulfate heptahydrate and the results of the two methods were compared. We found that the threshold values calculated by method ASTM-679 was within the range of concentrations identified with the scales method.     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇(Musca domestica vicina Macquart)为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对澳氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化。     

医院感染病原菌及耐药性监测报告

从３９０４ 例住院病人标本中分离出医院内感染病原菌７８１ 株,结合临床常用的１４ 种抗菌药物药敏试验结果进行整理分析。结果,革兰阳性球菌所占比例呈上升趋势,革兰阴性杆菌呈下降趋势。引起医院感染的主要病原菌为真菌、大肠埃希菌、克雷伯菌、肠球菌、金黄色葡萄球菌。２ 年间金黄色葡萄球菌对青霉素的耐药率已＞ ９３ ％ ,对第三代喹诺酮类的耐药率下降了１６．６６ ％ ～４０．８３ ％ 。肠球菌对万古霉素的耐药率上升了２７．５９ ％ 。克雷伯菌、沙雷菌、大肠埃希菌对头孢菌素类、第三代喹诺酮类的耐药率呈上升趋势。金黄色葡萄球菌、表皮葡萄球菌、肠杆菌属、铜绿假单胞菌对阿米卡星的耐药率呈下降趋势。     

A REAPPRAISAL OF THE USE OF MULTIDIMENSIONAL SCALING TO INVESTIGATE THE SENSORY CHARACTERISTICS OF SWEETENERS

Previous investigations of the sensory characteristics of sweeteners using a multidimensional scaling (MDS) approach, have involved sweeteners which were not matched for sweetness. Under such circumstances, part of the estimated distance between sweeteners is attributable to sweetness differences. This detracts from the value of the consequent MDS space, when the main objective is usually to investigate sensory characteristics other than sweetness. In this study, the MDS approach was applied to sweetener solutions which were matched for sweetness with 5% sucrose. The direction of any residual sweetness differences was identified by including 1,3,5 and 7% sucrose solutions, all matched to equal viscosity, in the study. From the resulting three dimensional MDS sweetener space, it was evident that Dimension 1 was almost exclusively due to sweetness differences whereas Dimensions 2 and 3 were devoid of influence from sweetness and hence represent the sweeteners with respect to their other sensory characteristics.     

SELECTION OF ASSESSORS BASED ON THEIR SKILL IN IDENTIFYING BASIC TASTES IN LOW CONCENTRATION SOLUTIONS

A method for the first step in the selection of trained sensory assessors, based on their skill in identifying basic tastes in low concentration solutions, was defined and evaluated. The solutions used were: 0.4 and 0.8% sucrose; 0.03, 0.04 and 0.06% citric acid; 0.08 and 0.15% sodium chloride; 0.02 and 0.03% caffeine. Concentration ranges were found adequate. The criterion for selection was to have over 65% correct answers. Out of 226 candidates who received the test, 141 (62%) were selected. The probability of a candidate having more than a certain percentage of correct answers was calculated. The influence of the dilution water quality on the perception of basic tastes was significant; distilled water was the most adequate.     

辛硫磷和溴氰菊酯混剂对家蝇抗性发展的影响

以家蝇（ＭｕｓｃａｄｏｍｅｓｔｉｃａｖｉｃｉｎａＭａｃｑｕａｒｔ）为试虫,用辛硫磷溴氰菊酯单剂及不同配比的混剂进行汰选试验。所有混剂选育的家蝇抗性发展都很缓慢,而单剂抗性发展都很快。增效试验表明,辛硫磷与溴氰菊酯混配有明显增效作用,特别是对抗性品系。生化分析结果表明,对溴氰菊酯的抗性发展与酯酶的酶活升高有关。对辛硫磷抗性发展与多功能氧化酶的酶活升高和乙酰胆碱酯酶敏感性降低有关。混剂选育的家蝇其对单剂的敏感性的变化及酶系的变化,随着混剂的配比而变化