Nitrosamines in Malt and Malt Beverages

National and local surveys of barley malt and barley malt-containing beverages for volatile N-nitrosamines were conducted by the Food & Drug Administration. Sixty-four samples of locally purchased beers had an average N-nitrosodimethylamine (NDMA) content of 3 ppb. Eleven of 44 Scotch whiskeys had nondetectable NDMA levels. A national sampling of domestic and imported malts revealed that 84% had NDMA concentrations of less than 10 ppb. Domestic and imported beers were also surveyed in a compliance program; 260 beer samples (180 domestic, 80 import) were analyzed. The domestic beers averaged less than 1 ppb and the imported beers averaged 1 ppb. These data indicate that the levels of NDMA in beer have been reduced significantly.     

Occurrence of N-nitrosodimethylamine in South Korean and imported alcoholic beverages.

Volatile N-nitrosamine (VNA) levels in South Korean and imported alcoholic beverages were determined between 1995 and 2002. A total of 147 alcoholic beverages, including lager beer, whiskey, liqueurs and traditional Korean alcoholic beverages (Chungju, Takju and Soju), were analysed for their VNA content by GC-TEA. Of eight VNAs (N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopyrrolidine (NPYR), N-nitrosomorphorine (NMOR), N-nitrosodibuthylamine (NDBA), N-nitrosopiperidine (NPIP), N-nitrosodiprophylamine (NDPA) and N-nitrosodiphenylamine (NDPhA)) only NDMA was detected. In 1995, NDMA was detected in 79.3% of domestic beers; the average was 0.8 microg kg-1. Seven years later, the average NDMA level for 18 domestic beers was 0.3 microg kg-1 and it was positive in 55.6% samples. In whisky and liqueurs, NDMA levels averaged <0.1 microg kg-1 in both 1995 and 2002. Average NDMA levels of Chungju in 1995 were <0.1 microg kg-1, but NDMA was not detected in 2002. Takju had undetectable levels of NDMA both times. In 1995, NDMA was found in four of six Soju samples, but in 2002, NDMA could not be detected.     

The occurrence of volatile N-nitrosamines in Estonian meat products

N-Nitrosamines (NAs) are a group of carcinogens, which have been detected in various meat products. The level of five NAs, namely N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine, N-nitrosopiperidine, and N-nitrosopyrrolidine was determined in 386 various samples of meat during 2001–2005. Raw, fried, grilled, smoked, pickled, and canned meat products were analyzed. For a sample cleaning the two-step solid-phase extraction with Extrelut and Florisil sorbents was used. NAs were separated by gas chromatography and detected by positive-ion chemical ionization using ammonia as reagent gas. The HP 6890 Plus GC/HP 5973 MSD was used in the selected ion-monitoring mode with pulsed splitless injection. In this work, the limit of detection and the limit of quantitation of NA were approximately 0.09 and 0.29 μg/kg, respectively, with about 85% recovery. NDMA was noted in above 88% of samples, NDEA in 27%, NPYR in 90%, NPIP in 65%, and NDBA in 33% at the mean levels of 0.85, 0.36, 4.14, 0.98, and 0.37 μg/kg, respectively. The level of total volatile NAs with the mean of 3.97 μg/kg was calculated.     

Volatile N-Nitrosamines in various fish products

N-Nitrosamines (NAs) are a group of carcinogens which have been detected in various fish products. In this study the level of five NAs (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosodibutylamine, N-nitrosopiperidine, and N-nitrosopyrrolidine) was determined in 294 various samples of fish, and in 77 samples of oil during 2001–2005. For the sample cleaning the two-step solid-phase extraction with Extrelut and Florisil sorbents was used. NAs were separated by gas chromatography and detected by positive-ion chemical ionization using ammonia as reagent gas. The HP 6890 Plus GC/HP 5973 MSD was used in the selected ion monitoring mode with pulsed splitless injection. In this work, the limit of detection and the limit of quantitation of NA were approximately 0.10 and 0.35 μg/kg, respectively with about 85%. The sum of the average of five NAs content in cold-smoked fish was found to be 1.92 μg/kg, in hot-smoked fish – 4.36 μg/kg, in fried fish – 8.29 μg/kg, in pickled fish – 5.37 μg/kg, in salted fish – 3.16 μg/kg, in salted/dried fish – 3.81 μg/kg, and in the fresh fish it was not detected.     

Solid-phase microextraction of N-nitrosodimethylamine in beer

N-nitrosodimethylamine (NDMA) is a highly active carcinogen that has been detected in trace levels in beers. Solid-phase microextraction (SPME) was used to develop a method for the extraction of NDMA from beer using headspace sampling and gas chromatography with mass spectrometry detection. Polydimethylsiloxane/divinylbenzene (PDMS–DVB) fibres were used to evaluate the influence of equilibrium time, ionic strength, extraction time and temperature by means of a factorial design. The method was validated calculating the linearity, reproducibility, limit of detection and limit of quantification. The method was applied to the quantitative analysis of NDMA combining the standard addition method with an internal standard method.     

NITROSAMINES IN ALCOHOLIC BEVERAGES

A limited survey was carried out to determine the nitrosamine content of several varieties of alcoholic beverages (beer and ale, whiskey, wine, cider, etc.) sold in Canada. Of 22 samples of different beers and ales analyzed all but one contained traces of dimethylnitrosamine; the overall mean level found was 1.5 ppb. Only one Canadian rye and one Scotch whiskey out of a total of 13 samples contained traces of either dimethylnitrosamine or diethylnitrosamine. All the 8 wines and 7 cider samples were negative.     

An investigation of the levels of N-nitrosodimethylamine, apparent total N-nitroso compounds and nitrate in beer

Over 170 retail samples of beer have been analysed for N-nitrosodimethylamine (NDMA), apparent total N-nitroso compounds (ATNC) and nitrate. Levels of NDMA ranged from below 0.1 up to 1.2 micrograms/kg with a mean of 0.2 micrograms/kg. ATNC was detected in 42% of the samples in concentrations of up to 569 micrograms (N-NO)/kg. The levels of nitrate ranged from less than 0.2 up to 143 mg/kg with a mean of 16.8 mg/kg. There was no correlation between the amounts of NDMA and ATNC found in the retail beers. Samples taken during the course of fermentation showed that NDMA was unaffected by the bacterial reduction of nitrate which causes ATNC formation. HPLC studies using a photolysis/chemiluminescence detector revealed that the ATNC in beer are highly polar species of as yet unknown identity.     

N-Nitrosamine Analysis in Beer Using Thermal Desorption Injection Coupled with GC-TEA

A fast and sensitive method is described for determining a mixture of volatile N-nitrosamines in beer and other malt products. It consists of direct extraction of the sample with dichloromethane, volume reduction, cleanup by trapping volatiles onto Tenax-TA, and thermal desorption injection into a capillary gas chromatograph-thermal energy analyzer. Average recovery of N-nitrosodimethylamine added to beer ranged from 70 to 81%. N-Nitrosodimethylamine and N-nitrosopyrrolidine were detected in 10 samples of various domestic and imported beers analyzed. Total volatile N-nitrosamine concentrations ranged from 0.03 to 1.10 ppb in beer. Minimum detection limit of the method was 0.01 ppb for N-nitrosodimethylamine, a 10-fold increase in sensitivity compared to other similar methods.     

Current incidence of N-nitrosodimethylamine in beers worldwide

A range of beers (n = 138) from 42 countries were analysed for the presence of N-nitrosodimethylamine (NDMA) using a chemiluminescence technique with a limit of quantification of 0.1 µg L^-1. The overwhelming majority of samples (79%) did not contain detectable NDMA, and only three samples exceeded 0.5 µg L^-1. No association was found between NDMA content and beer strength, type or geographical origin. It was noted that water can be a potential source of NDMA in beverages.     

Determination of Prolamins in Beers by ELISA and SDS‐PAGE

Coeliac disease is triggered by exposure to the prolamin protein fraction of wheat, barley, or rye. The prolamin content of five lager beers and one wheat beer were analyzed by sodium dodecyl sulfate—polyacrylamide gel electrophoresis (SDS‐PAGE) and immunoblotting and seven lager beers and three wheat beers were analyzed by enzyme‐linked immunosorbent assay (ELISA). Most of the lager beers were made from barley and some had varying amounts of rice or corn as adjuncts. One of the beers was “gluten‐free”, having been produced from corn and buckwheat without barley. The lager beer samples were gel‐filtered before ELISA or SDS‐PAGE analysis. Prolamin proteins were found in all but one beer which was made of corn, rice and barley and which was not the “gluten‐free” beer. ELISA analysis was done using a commercially available gluten assay kit. For lager beers, a barley prolamin standard for ELISA was propanol‐extracted from barley malt instead of using the prolamin standard of the gluten assay kit. As expected, the wheat beers contained much higher amounts of prolamins than the lager beers. The samples were studied by SDS‐PAGE to identify different prolamin fractions. Proteins having a relative molecular mass in the range of 8000–17,000 and 38,000 and above were detected in immunoblotting by the prolamin sensitive antibody in the lager beers.     

Volatile compounds isolated from rice beers brewed with three medicinal plants

The volatile compounds and physicochemical properties of rice beers brewed with three medicinal plants, namely Acanthopanax senticosus (Siberian ginseng), Scutellaria baicalensis (baikal skullcap) and Cornus officinalis (Japanese cornel) were analysed. The rice beers were produced and fermented from unhulled ground rice, malt, and medicinal plant extracts. The medicinal plant extracts, used at 5 and 10 % (v/v) were blended with wort before fermentation. Compared with a draft beer fermented without rice, the rice beers had lower levels of pH, acidity, amino acid content and reducing sugars. Of the rice beers, the beer with the addition of 10% Japanese cornel had the highest colour value and foam stability. The volatile compounds of the rice beers were extracted using a solvent‐assisted flavour evaporation apparatus and analysed by gas chromatography–mass spectrometry. The rice beer with 10% Siberian ginseng showed the most diverse volatile profile, in that 54 kinds of volatile compounds were detected. The rice beer with 10% Japanese cornel had the highest relative amount of volatile chemicals of all of the rice beers. Lactones such as γ‐hexalactone, γ‐nonalactone and γ‐decalactone were detected in all of the rice beers. Copyright © 2013 The Institute of Brewing & Distilling     

Investigations of Edible Oils for Volatile Nitrosamines

Twenty-one commercial edible oils and five margarine samples were purchased locally and analyzed for nitrosamines (NAs) by a gas-liquid chromatograph interfaced with a Thermal Energy Analyzer. N-nitrosodimethylamine (NDMA), at levels of 0.22–1.01 ppb, was the only volatile apparent NA detected. These levels were found in 7/7 corn, 6/6 olive, 2/2 sunflower, 1/3 soybean, 2/3 undesignated oils, and 4/5 margarine samples. The other three oils and one margarine sample showed no NDMA at the lower limit of 0.1 ppb. These levels of nitrosamine detected in the edible oils tested were much lower than the levels previously reported.     

Use of High Hydrostatic Pressure to Increase the Content of Xanthohumol in Beer Wort

During beer production, xanthohumol (XN) extracted from hop through wort boiling is largely converted into its isomeric flavanone, isoxanthohumol (IXN), due to the thermal treatment. XN has a great biological interest as a functional compound (being anti-carciogenic, antioxidant, anti-inflammatory, and anti-infective) and its loss leads to beers with very small amounts of XN and reduced functional properties. In this work, we studied the use of high-pressure treatments (HP; 100, 200, 250, 300, 400 and 500 MPa for 5 min and 250 and 400 MPa for 15 min), applied to previously boiled worts with a second hop dosage, as an extractive procedure, to produce XN-enriched beer worts. The results indicated that beer worts processed by HP showed higher levels of XN. The best results were obtained for 250 MPa, 5 min, resulting in an increase of 4-fold in XN, compared with beer worts produced only by boiling, and 2-fold compared with a method mimicking a recently proposed methodology also intended to improve XN in wort (called XAN method). Combinations of lower pressures with short pressurisation periods proved to be more efficient to increase the amount of XN in the wort. Moreover, HP-processed worts showed lower levels of IXN compared with samples produced by the mimicked XAN method. Physical–chemical characteristics of worts (pH, colour, bitterness and original extract) produced by HP, were similar to those produced only by boiling. These results clearly indicate the potential of using HP treatments to increase the XN content in beer wort, together with less isomerisation to IXN, and open promising possibilities to produce beers with higher amounts of XN, with potentially enhanced functional properties and health promoting properties.     

Influence of the range of molecular weight distribution of beer components on the intensity of palate fullness

The effect of the molecular weight distribution (MWD) of the beer components on the intensity of palate fullness was studied. The range of MWD for different types of maltodextrin and for nine commercial pilsner beers was determined using AF4/MALLS/RI. Sensory analysis (DIN 10952, DIN ISO 4120 and DIN 10963/ISO 8587) was carried out by a trained Deutsche Landwirtschafts-Gesellschaft, German Agriculture Society (DLG) tasting panel. The intensity of the palate fullness of a spiking trial (beer + maltodextrin) and the threshold concentration of the maltodextrins in beer was determined. The association between the ranges of MWD and the intensity of the palate fullness of the commercial pilsner beers was studied. AF4/MALLS/RI and sensory analysis were used to study the effect of variations of the brewing process on the range of MWD and the palate fullness of beer. The intensity of the palate fullness differed significantly (p < 0.0001) within commercial pilsner beers. Strong associations were found between the range of MWD of the commercial beers and intensity of the palate fullness (p < 0.05). The range of MWD of the commercial pilsner beers (3–13 kDa) corresponded to those found for maltodextrins with intermediated range of MWD (3.4–22.3 kDa). The threshold concentration was higher (p < 0.0001) for those maltodextrins with lower range of MWD (2.7–8.9 kDa). Beers produced with malted barley with Kolbach Index of 36 % exhibited a higher range of MWD (2.9–13 kDa) compared to those with Kolbach Index of 41 % (1.7–11.6 kDa). Slight differences in the palate fullness were perceived according to variations on the initial temperature of the mashing process among those beers produced using Kolbach Index of 36 %, whereas a great difference (p < 0.0001) was perceived using Kolbach Index of 41 %. The intensity of the palate fullness of the pilsner beer was influenced by the range of MWD of the beer components which would vary according to differences in the mashing process and of the quality of the malted barley.     

FLAVOUR AND HAZE STABILITY DIFFERENCES IN UNHOPPED AND HOPPED ALL-MALT PILSNER BEERS BREWED WITH PROANTHOCYANIDIN-FREE AND WITH REGULAR MALT

Unhopped and hopped all-malt Pilsner beers were brewed with proanthocyanidin-free malt (ant 13–13×Rupal) and with regular malt (Gatinais). A tannin-free hop extract was used. The beers were analysed chemically and presented both to an expert and an untrained taste panel to detect possible preferences and differences in bitterness and astringency. The colloidal stability of the proanthocyanidin-free beers is superior to that of the regular ones. Paired comparison tests show that at the 3% significance level there is a difference in the appreciation of bitterness of the unhopped beers, the proanthocyanidin-free beer being the more bitter. The panelists do not detect differences in astringency and they have no preference for either beer. In the case of the hopped beers no bitterness, astringency or preference differences are found in paired comparison tests. Finally, no differences between hopped and unhopped proanthocyanidin-free and regular beers were found at the 5% significance level when using both an expert and an untrained panel in triangular experiments.     

啤酒酿造中二甲基硫、甲基蛋氨酸、二甲基亚砜含量的变化与控制

为控制啤酒风味物质二甲基硫（dimethyl sulfide,DMS）的含量,实验运用气相色谱-氢火焰离子化检测器测定了15 种国内市售啤酒样品DMS的含量,并研究了啤酒酿造中DMS、甲基蛋氨酸（S-methylmethionine,SMM）、二甲基亚砜（dimethyl sulfoxide,DMSO）的含量变化。结果表明,抽取的国内市售啤酒样品中有47%的样品DMS含量超出60 μg/kg,特别是爱尔啤酒（Ale）中71%的样品DMS含量超出60 μg/kg,最高值达到105 μg/kg;实验抽检10 种国内市售麦芽DMS、SMM、DMSO含量,不同麦芽间DMS与二甲基硫前驱体（dimethyl sulfide precursor,DMSP）差异较大,差异最高达160%,且多数小麦芽的DMS与DMSP含量低于澳麦芽。实验研究了麦汁煮沸、发酵过程中的DMS及DMSP含量的变化,在100 ℃、pH 5.6时,麦汁煮沸40 min后DMS含量比初始含量降低92%,SMM的半衰期为31 min。发酵过程中DMS含量在发酵旺盛期时有明显的下降,最高下降41%。     

Investigation into Benzene,Trihalomethanes and Formaldehyde in Chinese Lager Beers

Beers brewed commercially in China have been surveyed for the presence of a number of potential contaminants, including benzene, trihalomethanes and formaldehyde. Of 84 beers only 6 contained detectable benzene, at concentrations ranging from 1.9 to 7.1 μg/L (mean of 4.0 μg/L). Further investigations suggested that the source of the benzene could be the carbon dioxide used for carbonation. Trihalomethanes were measured in 107 beers (consisting of 27 Chinese brands) by headspace gas chromatograph with average and maximum concentrations of 1.2 μg/L and 5.2 μg/L respectively. Total trihalomethanes were also measured in water samples from different brewing sites. Concentrations varied from 2.7–46.9 μg/L, except for one sample which contained 79.3 μg/L. Formaldehyde was measured in 29 beers (including 7 imported brands) using solid‐phase microextraction with on‐fiber derivatization. Formaldehyde levels were between 0.082‐0.356 mg/L. None of the beer samples exceeded WHO drinking water criteria for benzene, trihalomethanes or formaldehyde.     

Development of a quantitative method for organic acid in wine and beer using high performance liquid chromatography

This study was conducted to compare the organic acid content in liquors (red wine, white wine, and beer) using three different high-performance liquid chromatography analysis methods. Post-column reaction methods (method 2 and 3) were found to be more promising than UV-detection method (method 1). Using method 2 (two columns), the analyzed red wine was found to contain 2,652.4 mg/L tartaric acid and 1,392.9 mg/L lactic acid but relatively lower amounts of malic acid (271.0 mg/L). Furthermore, tartaric acid (1,160.8–2,749.1 mg/L) and malic acid (470.2–3,107.9 mg/L) were the major components in white wine. Beers were analyzed using method 3 (one column). In the analyzed foreign beers, lactic acid (95.9–226.4 mg/L), malic acid (62.2–110.5 mg/L), acetic acid (93.5–183.8 mg/L), and succinic acid (37.0–56.2 mg/L) were detected. Similar to the foreign beers, the contents of succinic acid in the domestic beers were the lowest. The proposed methods could be useful for quantitative analysis of organic acids in wine and beer.