Vanillin analysis

Vanillin, being an aldehyde, is able to form acetals and hemiacetals. Therefore, in flavor formulations using high concentrations of vanillin in conjunction with carriers such as propylene glycol, a glc analysis often shows a reduced vanillin peak after storage of the compounded flavor, and the presence of new peaks indicating acetal formation. Addition of about 0.5% of water to the formula reverses the reaction, ie, there is a reduction of acetal, and the reappearance of vanillin peaks. 

Determination. Various classical techniques are used for the analysis of vanillin, including colorimetric, gravimetric, spectrophotometric, and chromatographic (tic, gc, and hplc) methods. The Food Chemical s Codex (FCC) prescribes infrared spectrophotometry for identifying and testing vanillin. However, more vanillin analyses are made by either gc or hplc. 

Hplc techniques are used to routinely separate and quantify less volatile compounds. The hplc columns used to affect this separation are selected based on the constituents of interest. They are typically reverse phase or anion exchange in nature. The constituents routinely assayed in this type of analysis are those high in molecular weight or low in volatility. Specific compounds of interest include wood sugars, vanillin, and tannin complexes. The most common types of hplc detectors employed in the analysis of distilled spirits are the refractive index detector and the ultraviolet detector. Additionally, the recent introduction of the photodiode array detector is making a significant impact in the analysis of distilled spirits. 

Benzoic aldehydes mainly cover syringaldehyde and vanillin. Natural vanilla is prepared from the seeds (beans) of Vanilla planifolia, which may contain about 21 mg/ 100 g FW total phenols, including the major components vanillin (19.4 mg/100 g FW), 4-hydroxybenzaldehyde (1 mg/100 g FW), and vanillic acid (0.4 mg/100 g FW) (Clifford 2000b). In mango, vanillin has been found as free as well as vanillyl glu-coside (Sakho and others 1997). It has also been found in lychees (Ong and Acree 1998) and wines (Moreno and others 2007). For analysis of both brandy and wine aged in oak barrels, the limits of detection were found to be 27.5, 14.25, 14.75, and... 

Papaveraceae, alkaloids in, 2 75 Papaverine, 2 87-88 from vanillin, 25 554 Paper, 18 89-132. See also Papermaking analysis of moisture and fluid resistance for, 18 101... 

The price of synthetic vanillin has dropped to about 10 kg-1 due to increased production in China, which is now the number one supplier. In view of the very large price difference, analytical methods (isotope analysis) have been developed to distinguish between natural and synthetic vanillin. 

The precipitate was then analyzed using high performance liqnid chromatography (HPLC) to reaffirm the results as characterized by the IR analysis. The precipitate was collected and dissolved in an acetone solntion with water (1 2 v/v) acting as the solvent before the analysis was done. Finally, the 1.0 ppm concentrated sample was injected into a HPLC machine. The chromatogram shows a peak at the retention time (Rj) which is almost the same as the retention time of standard vanillin with the same concentration. Figure 9.4 presents the HPLC chromatograms of the vanillin sample and the standard vanillin. 

The H-FT-NMR spectra were obtained from a Bruker Avance 300 operating in the FT mode at 400 MHz under total proton decoupled conditions. The spectra were recorded at 40°C from 200 mg sample vanillin dissolved in 1 mL CDClj after 3,000 scans. A 90° pulse flipping angle, a 26.6 ps pulse width and a 1.74 s acqnisi-tion time were employed. There was no significant difference in the stractnre of vanillin precipitated from crystallization process and standard vanillin based on H-NMR analysis (Fig. 9.5). Incomplete dissolntion of the sample may becanse of the rmexpected high signaPnoise ratio. The peaks show that the chemical shifts for both of vanillins are very similar. 

TLC analysis of samples was conducted on silica-gel plates carefully spotted with 10-20 pg of standard compounds, and 30 pL of bioconversion reaction samples. Plates developed with 75 25 1 (v/v/v) CH2CI2/CH3CN/HCOOH solvent may be visualized with a 254 nm UV lamp and/or by spraying with a 30 % w/v phosphomolybdic acid/ 95% ethanol spray reagent followed by gentle heating. Rf values of standards are vanillyl alcohol, 0.8 vanillic acid, 0.5 and vanillin 0.4. 

Broadhurst RB, Jones WT (1978) Analysis of condensed tannins using acidified vanillin. J Sci... 

NT450 Demian, B. A. Trace analysis of vanillin in tobacco. J Liq Chromatogr... 

Labuda IM, Goers KA, Keon KA (1993) Microbial bioconversion process for the production of vanillin. In Schreier P, Winterthaler P (eds) Progress in flavour precursor studies analysis, generation, biotechnology. Proceedings of the international conference, Wuerzburg. Allured, Carol Stream, pp 477-482... 

Methods of analysis are needed to determine total phenolic content and the relative content of phenolic fractions by means of their different characteristics. Many analytical methods used for phenols have been empirical and not easily reproduced or rationalized (I). Procedures that are based on sound chemical principles and that are sufficiently verified deserve wider application. We are concerned here with recent work on such analyses for phenols in wines. Application cf these results may help solve a major problem in phenol research—the many different, too empirical, unrelatable values (ml KMn04, vanillin-to-leucoantho-cyanin ratio, etc.) obtained in different ways by different researchers. Uniform use of verified methods and uniform standards and methods of expressing results will aid in developing an understanding in this field. 

Oxidation with Barium Dioxide and Alkali. The alkali lignin was boiled in alkaline solution with an excess of barium dioxide and a little cupric hydroxide under conditions reported to give high yields of vanillic acid (5, 6). Analysis indicated only 13.8% ether extractives and the following yields on the basis of the original alkali lignin 2.8% vanillic acid, 0.4% p-hydroxybenzoic acid, 0.1% vanillin, 0.2% acetovanillone, and a trace of />-hydroxybenzaldehyde. 

The installation of the amine functionality at C5 is accomplished by mesylation of 41 followed by azide displacement to give 44 (71% yield over four steps). The P-aminopropanamide 13 is then introduced directly to the lactone under 2-hydroxypyridine catalysis to give the penultimate intermediate 45. Reduction of the azide and isolation as the hemifumarate salt provides aliskiren hemifiimarate (l).37 Based on the information disclosed to date, the synthesis of aliskiren is accomplished with an overall yield of 14% from iso vanillin 14 with a longest linear sequence of 15 steps. Given the complexity of aliskiren, this is a remarkably efficient process, and it should be noted that this analysis likely only establishes a lower limit of efficiency, as further optimization of the route on a manufacturing scale is expected. 

The biosynthetic origins of vanillin can be determined by the analysis of naturally occurring isotope ratios (in practice, chiefly 2H/1H and 13C/12C), using isotope ratio-mass spectrometry (IR-MS) and nuclear magnetic resonance (site-specific natural isotope fractionation SNIF-NMR ). Isotopic ratio... 

Waliszewski et al. (2007b) described a simple and rapid HPLC technique for vanillin determination in alcohol vanilla extract, and the method has been applied successfully for the determination of vanillin in some commercial extracts for routine analysis. de Jager et al. (2007) developed a LC-MS method for the determination of vanillin, coumarin and ethyl vanillin in vanilla products using LC-electrospray ionization in the positive ionization mode. The limits of detection for the method ranged from 0.051 to 0.073 pg/ml. 

---