Aldehydes content

Acrylic acid Very low aldehyde content. Undisclosed 99.95% Falling him Undisclosed Undisclosed... 

PET suitable for bottle manufacture is produced by a modified process. Here the high-viscosity polymer melt is subjected to a rapid quenching in water to produce clear amoiphous pellets. These are further polymerised in the solid phase at temperatures just below the T . This is useful to reduce aldehyde content, since aldehyde-forming degradation reactions occur less in the lower temperature solid phase polymerisations. Aldehydes can impart a taste to beverages and it is important to keep the aldehyde content to below 2.5 p.p.m. 

Shimomura, O., Johnson, F. H., and Morise, H. (1974a). The aldehyde content of luminous bacteria and of an aldehydeless dark mutant. Proc. Natl. Acad. Sci. USA 71 4666-4669. 

The simple aldehydes react with neutral sulphites to form salts of aldehydesulphurous acids. In this reaction free alkali is formed, and the aldehyde content of a solution can also be determined in this way if the alkali is titrated. 

The secretion of the red hartebeest is characterized by its high aldehyde content. Of an estimated 100 detectable constituents, 25 are saturated and unsaturated aliphatic aldehydes [138]. Because the aldehydes are highly susceptible to autoxidation, the secretion could therefore only be used for shortterm territorial marking. On the other hand, the conversion of the aldehydes to carboxylic acids could also be transmitting information with a date stamp . In this regard, it is debatable whether fatty acids, which are almost ubiquitous in the animal world, really are such major carriers of semiochemical information in all of the many species in which they are purported to fulfill this role. 

Materials. Cio>Cl2>Cl4,Cl6,Cl80H were Shanghai Chemical Reagent Co. extra pure materials, purity > 98%. Ethylene oxide was purified with monoethanol amine to an aldehyde content < 0.03%. Mixed alco-... 

Aldehyde. The aldehyde content of the propellant shall be determined in accordance wi th ASTM D2191-65 with the following exceptions ... 

The composition of bitter orange oil differs from that of sweet orange oil i.e., its aldehyde content is lower and its ester content is higher [369-370a, 370d, 370e, 394, 423-428]. 

The aldopentoses and aldohexoses, which are completely hydroxyl-ated 4-hydroxypentanals and 5-hydroxyhexanals, respectively, contain only a very small proportion (<0.05%) of the aldehydo form at equilibrium (see Table II). The aldehyde content of the 2-deoxyaldoses is only slightly higher. 

The acetaldehyde-sulfurous acid compound has the properties of a sulfonic acid with C-S linkage rather than an ester structure as once assumed. It is properly 1-hydroxyethane sulfonic acid (23, 24) and is highly acidic (25). Samples of concentrated heads from commercial aldehyde columns having aldehyde contents of 5-13% gave pH values of 0.7-0.9 and contained high levels of copper (25). 

The aldehyde content of Novolac resins is insufficient to render the resin thermosetting, hence, they are true thermoplastics provided that a curing agent is not added. Novolacs may be stored indefinitely in the pulverized state at moderate temperatures even mixed with curing agent. 

This group evaluated the impact of changes in fatty acid composition on headspace aldehyde content of fresh pork and demonstrated the utility of these saturated aldehydes as an indicator of lipid oxidation. 

Basic Protocols 8 and 9 look at specific groups of compounds, aldehydes and esters, which are of more interest to flavor houses and research scientists. For flavorists, the strength of citms flavor is determined from the aldehyde content, while the fruity aroma is attributed to the ester content. Over the years, these procedures have been modified. Basic Protocol 8 is a titration method to determine aldehyde content in citms oils. It was originally developed for lemon oil however, it is also applicable to other citms oils. Alternate Protocols 4 and 5 also produce similar results. Alternate Protocol 4 is based on... 

Aldehyde content is considered an important flavor note included in the standard of identities for citrus oils. The flavor strength of an oil is based on the aldehyde content, where higher is better. The two major aldehydes are acetaldehyde and octanal. The quantification of aldehydes is based on the reaction of citral in the sample with a hydroxylamine solution, followed by titration with KOH in the presence of ethyl orange indicator. It is modified from AOAC Method 955.32 (AOAC, 1990c Redd et al., 1986). This method was originally developed for lemon oils however, it is applicable to other citrus oils. 

Optical activity (refractive index (T ) specific gravity (SG), and aldehyde content from NRC (1981). Ester content from Kimball (1999). 

Procedure. 10 c.c. of the spirits, brought to 50% strength, are placed in one test-tube and 10 c.c. of the standard solution in another, 4 c.c. of Schiff s reagent being added in each case and the tubes then dosed, shaken and left for 20 minutes. If the two liquids then have about equally intense colorations, they are compared in the colorimeter. Otherwise the test is repeated, a less quantity being taken of the alcohol giving the deeper coloration and this made up to 10 c.c. with pure 50% alcohol this is necessary because the intensities of the coloration are not proportional to the aldehyde-content, except when the differences are small. When sensibly similar colorations are obtained, the liquids are compared in the Duboscq colorimeter. 

A mixture of mandarin fruits with oranges may be detected by ultraviolet spectra and results in inconsistent flavor quality and lower aldehyde contents. 

The quantity of water used to make the oil-water emulsion also affects quality. Aldehyde concentrations decrease with increasing proportions of aqueous phase in an emulsion. This decrease may be due to insoluble solids which absorb aldehydes in the emulsion. However, using large quantities of water will increase oil yields. Therefore, a balance should be sought between aldehyde content, water usage, and oil yield. Current industry water usage for oil recovery varies widely above and below 28 / 100 kg fruit depending on the type of recovery equipment (24, 25). 

Of cultural effects, fruit variety probably has the most influence on oil quality, particularly aldehyde content (12). 

The Pharmacopea and the Essential Oil Association of the United States require the following analyses as an index of oil purity refractive index, optical rotation, refractive index and optical rotation of a 10% distillate, specific gravity, aldehyde content, evaporation residue and ultraviolet absorption spectrum (Kesterson et al. 157 and Sale 29). 

Cellulose can be oxidized to different degrees of C6-aldehyde content by photolysis of the 6-azido-6-deoxy derivatives [51]. The / -elimination reaction of the 6-aldehyde (Scheme 2) may lead to terminal double bonds exhibiting a UV absorption Umax = 250 nm) [52,53]. With model C6-aldehyde celluloses, /3-elimination started at 30 °C at pH 9 at elevated temperatures (80 °C) -elimination was detected already at very low pH levels (pH 3.5). Similar results were obtained with HOCl-oxidized pulps, with -elimination starting at room temperature at pH 8.5 (unpublished results). 

Raw stock phosphorus thiotrichloride (the boiling point is 124-125 °C, PCI3 content is not more than 3%) absoluted ethyl alcohol (the alcohol content is at least 99.7%, aldehyde content is not more than 20 mg/1) sodium hydroxide is flaky solid NaOH, type A (NaOH content is at least 95%) liquid caustic (the density is 1.44 g/cm3, NaOH concentration is at least 42%) benzene (the boiling point is 80.1 °C, the density is 0.875-0.88 g/cm3) /7-nitrophenol (the melting point is 114 °C, the density is 1.479 g/cm3 it dissolves badly in water but well in organic solvents in the diy form explodes by shock) hydrochloric acid (the density is 1.19 g/cm3, HCI content is 27.5%) soda Na2C03 (the density is 2.53 g/cm3, it dissolves well in water). 

Since the rate constants for both oxidation steps are of the same order of magnitude (3) different types of aldehydes will be present in partial oxidized dextran. Due to the occurrence of these consecutive reactions the aldehyde content in a partial oxidized dextran can not be predicted from the amount of periodate added. 

Reduced dextran dialdehydes. The reaction of dextran (D-OH) with sodium metaperiodate is a two step reaction leading to different kinds of aldehyde functions. Although the aldehyde content can not be precisely predicted from the amount of periodate added, by approximation 1.5 equivalents of periodate are required per dialdehyde structure. By varying the amount of periodate added to the polysaccharide dextran dialdehydes with variable degree of oxidation were obtained. In order to avoid interaction of the polyaldehyde (D-CH=0) with the dextranases the aldehyde groups were subsequently reduced by reaction with sodium borohydride ... 

---