Confirmatory method for the determination of volatile congeners and methanol in Turkish raki according to European Union Regulation (EEC) No. 2000R2870: Single-laboratory validation

PubMedID: 21563697A method described by European Union Regulation (EEC) No. 2000R2870 was validated and supported by GC/MS analysis for the determination of volatile congeners and methanol in Turkish raki. The method was validated in terms of specificity, accuracy, precision, LOD, LOQ, linearity, and robustness. The specificity of the method was demonstrated, and the method showed excellent accuracy (97.5-100.1%). Linearity was checked in the ranges of 0.200-26.390 mg/100 mL for more volatile compounds and 1.155-48.00 mg/100 mL for less volatile compounds, after concentrations found in Turkish raki were taken into account. The calibration curves of all analytes showed good linearity (R 2 > 0.998). The within-and between-day precision (RSD) values of 11 analytes were in the range of 0.18-4.50%. The LOD and LOQ values were in the range of 0.014-0.362 and 0.045-1.085 mg/100 mL, respectively. The method can be used as an absolute quantification method for the determination of volatile congeners and methanol in Turkish raki and for QC

Methanol and major volatile compounds of Turkish raki and effect of distillate source

Turkish Raki is the traditional anise flavoured distillate beverage produced mainly from a grape distillate called suma. Two types of Raki are produced in Turkey according to the distillate source. They are Type I - a fresh grape Raki produced only from suma and Type II - a Raki produced from a blended distillate of suma and alcohol of agricultural origin (mainly molasses). In this study the content of ethanol, methanol, distillate based major volatile compounds (aldehydes, esters, higher alcohols), aniseed based anethole and estragole, volatile acid and sugar values in two types of commercial Raki samples (40 samples) was deter- mined and the effect of distillate source on the composition was examined. The distillate and the aniseed based major compounds of the Raki samples were analysed by direct injection with a GC-MS-FID according to the European Commission Reference Method. The results of variance analysis and PCA showed that there was a significant difference between the two types of Raki samples. Total volatiles (esters and higher alcohols), methanol, trans-anethole, estragole and sugar values were higher in the samples made from suma alone. All of the analysed component levels of the Turkish Raki samples were in compliance with Turkish Distilled Beverage Regulations. The methanol levels ranged between 28.00-50.87 g/hL absolute alcohol (AA) in Type I samples and 22.03-41.06 g/hL AA in Type II samples. Distillate based total volatiles levels ranged between 136.12- 147.88 g/hL AA, with a mean value of 142.88 g/hL AA, in Type I samples and 102.44-113.45 g/hL, with a mean value of 107.9 g/hL, in the Type II samples. The anise based compound trans- anethole levels were significantly higher in the Type I samples (1,298-1,570 mg/L) than in the Type II samples (1,014-1,199 mg/L). According to distillate based volatiles, the Turkish Raki has a valuable content of volatile substances compared to other anise flavoured spirits. © 2011 The Institute of Brewing & Distilling

Enhanced production of isoamyl acetate from beet molasses with addition of fusel oil by Williopsis saturnus var. saturnus

Fusel oil which contains high level of amyl alcohols (approximately 45-55%) is a by-product obtained from the distillation of alcohol made by fermentation of molasses. Williopsis saturnus is a yeast which is able to convert isoamyl alcohol into isoamyl acetate. The aim of this study was to increase the formation of isoamyl acetate by the addition of fusel oil at the ratios of 1%, 2% and 3% (v/v) to molasses based fermentation medium using W. saturnus. It was found out that bioconversion of added fusel oil into isoamyl acetate was possible and an addition of 1% fusel oil led to an increase in isoamyl acetate concentration from 118 to 354 mg/L. © 2008 Elsevier Ltd. All rights reserved.This research has been funded by grants under the Academic Research Projects Unit of Cukurova University of Turkey (Project Nos. ZF2004BAP20 and ZF2004D34). The authors would like to thank HUT Culture Collection for providing yeast strain, Ozmaya Co. for molasses and Malatya Sugar Factory for fusel oil

Differentiation of Turkish rakies through headspace solid-phase microextraction and gas chromatography-mass spectrometry analysis

Composition of flavour compounds from several commercial raki samples was determined through headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry (GC-MS). The extraction of volatile compounds was performed using a 75 µm CAR/PDMS fibre. Forty three volatile compounds were identified. The major compounds were trans-anethole (86.47-94.19%), valencene (1.15-6.77%), estragole (2.66-5.46%), and cis-anethole (0.72-2.33%). Principal component analysis (PCA) enabled the differentiation of the raki samples thanks to compounds arising mainly from aniseed. © 2011 The Institute of Brewing & Distilling

Production of isoamyl acetate from sugar beet molasses by Williopsis saturnus var. saturnus

Three strains of Williopsis saturnus var. saturnus were employed for the production of natural isoamyl acetate (the character impact compound of banana flavour) using sugar beet molasses as the carbon source and batch cultivation at 25°C under anaerobic conditions. Of the three strains, strain HUT 7087 was the best producer of isoamyl acetate, producing 20.7 mg/L. Sugar beet molasses was deemed to be an acceptable carbon source for the production of this flavour compound. © 2008 The Institute of Brewing & Distilling

Effects of fermentation temperature and aeration on production of natural isoamyl acetate by williopsis saturnus var. saturnus

PubMedID: 23862159Isoamyl acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Williopsis saturnus var. saturnus is a yeast which can produce isoamyl acetate by esterification of amyl alcohols with acetyl coenzyme A via fermentation. The evaluation of this kind of production as an alternative way to obtain natural banana flavour could be possible, if the levels produced were high enough to make a commercial product. In this study, the effects of temperature (15°C and 25°C) and aeration (aerobic, semiaerobic, and anaerobic) on the production of isoamyl acetate by Williopsis saturnus var. saturnus from sugar beet molasses were examined. According to the results obtained, isoamyl acetate production rate and specific productivity were higher at 25°C than at 15°C and at semiaerobic condition than aerobic and anaerobic conditions. Williopsis saturnus var. saturnus showed a production rate of 0.703 mg L-1 h-1 and a specific productivity of 0.0297 mg L-1 cell-1 h-1 isoamyl acetate with semiaerobic condition at 25°C. The maximum amount of isoamyl acetate reached with these conditions was 118 mg/L. © 2013 Murat Yilmaztekin et al

Physico-chemical characteristic and fatty acids compositions of cottonseed oils [Pamuk Yağlarının Fiziko-Kimyasal Özellikleri ve Yağ Asitleri Kompozisyonu]

In this study, three cotton genotypes of species Gossypium hirsutum L., Cukurova 1518, PAUM 15 and BA 119 were investigated for their some physicochemical properties of oils such as free fatty acids, peroxide value, iodine value, unsaponifiable matter, total carotenoid and tocopherol contents and fatty acids composition in Cukurova region in Turkey. Seed oil content ranged 17.2-19.6% and PAUM 15 was found to be genotype with the highest oil content. The range of other physicochemical properties and their values are as follows; free fatty acids 1.7-2.8%, peroxide value 5.3-6.0 meq O2 kg-1, unsaponifiable matters 2.1-2.3%, iodine value 102-110, total carotenoid content 119-140 mg kg-1, total tocopherol content 887-920 mg kg-1, linoleic acid 52.00-55.82%, palmitic acid 24.85-25.63%, oleic acid 14.06-17.00%, stearic acid 3.01-3.13% in the cottonseed oils. PAUM 15 was determined to be more suitable for food consumption as edible oil due to its highest oil content and quality characteristics than the others genotypes. © Ankara Üniversitesi Ziraat Fakültesi

Fruit Weight, Total Phenolics, Acidity and Sugar Content of Edible Wild Pear (Pyrus elaeagnifolia Pall.) Fruits [Fruchtgewicht, Gesamt-Phenolgehalt, Säure- und Zuckergehalt zum Verzehr geeigneter Früchte der Wildbirne (Pyrus elaeagnifolia Pall. = Ölweidenblättrige Birne)]

Wild pear (Pyrus eleagnifolia) is a naturally grown species mainly in inner Anatolia and its edible small fruits are traditionally consumed by local peoples and are called “Ahlat” in Turkey. Its seedlings are also used as rootstock for commercial pear cultivars. In this study, we reported first time pomological characteristics and biochemical compositions in fruits of a wide number selected wild pears genotypes (Pyrus eleagnifolia Pall.) from inner Anatolia. The obtained results revealed that there were significant differences among wild pear genotypes for all analyzed parameters. Fruit weight, total phenolics, total acidity and total sugar contents of the fruits varied from 4.71 to 27.09 g, 42.79 to 119.14 mg GAE/100 g, 0.20 to 1.40 g/100 g and 8.36 to 19.31 g/100 g, respectively. Considering these values, it was concluded that naturally grown wild pears of Anatolia with their rich salubrious biochemical compounds could reliably be used as a food source for humans. © 2015, Springer-Verlag Berlin Heidelberg

Interlaboratory study of ethanol usage as an internal standard in direct determination of volatile compounds in alcoholic products

A collaborative interlaboratory study on the method of direct quantitation of volatile compounds in spirit drinks and alcoholic products was conducted. The discussed method applies ethanol, the major volatile component of an alcoholic product, as an internal standard. In this study 9 laboratories from 4 different countries were supplied with standard solutions for gas chromatographic measurements. Five aqueous ethanol 40% (v/v) standard solutions containing target compounds in concentrations ranging from 10 mg/L to 400 mg/L of absolute alcohol were prepared and sent to the participants for quantification of acetaldehyde, methyl acetate, ethyl acetate, methanol, 2-propanol, 1-propanol, 2-methyl-1-propanol, 1-butanol and 3-methyl-1-butanol. The interlaboratory study was evaluated according to the ISO 5725 standards and the Eurachem guide. The within-laboratory precision varied between 0.4% and 7.5% for all samples and compounds, showing a sufficiently high repeatability of the method. The between-laboratory precision was found to vary within a satisfactory range of 0.5% ÷ 10.0%. Precision of the method was well within the range predicted by the Horwitz equation for all analytes. The analysis of trueness showed that the bias of the method is insignificant at the significance level α = 5%. The determined concentrations of the analytes compared well to the gravimetrical values thus showing very satisfactory accuracy of the method. The results of the interlaboratory study confirmed that “Ethanol as Internal Standard” method is robust and reliable and can be used as a standard reference method for analysing volatile compounds in water-ethanol samples. The possibilities of method validation according to the previously obtained experimental data were shown