Der Einfluß von Acetaldehyd und Wasser auf die 14C-Bestimmung bei WeinalkoholDie Bestimmung von 14C im Äthanol von Wein wird nicht signifikant beeinflußt, wenn die Destillation sorgfältig durchgeführt wird und der Wasser- und Aldehydgehalt 10 % (v/v) bzw. 0,5 % (v/v) nicht übersteigt

de Villiers, Johanna F.

Hanekom, A. N.

Houtman, A. C.

English

JKI Open Journal Systems (Julius Kühn-Institut)

Vitis 17, 168-169 (1978) Fruit and Fruit Technology Research Institute and Oenologlcal and Vltlcultural Research Institute Stellenbosch, South Africa The influence of acetaldehyde and water on the determina-tion of 14C in wine alcohol by A. N. HANEKOM, JoHANNA F . DE VILLIERS and A. C. HouTMAN Der Einfluß von Acetaldehyd und Wasser auf die 14C-Bestimmung bei Weinalkohol Z u s a m m e n f a s s u n g . - Die Bestimmung von "C im Äthanol von We.in wird nicht signifikant beeinflußt, wenn die Destillation sorgfältig durchgeführt wird \md der Wasser- und Aldehydgehalt 10°/o (v/v) bzw. 0,50/o (v/v) nicht übersteigt. The determination of 14C in wine alcohol has lately been used to examine wines for the probable presence of synthetic ethanol (cf. SIMON et al. 1968). For this purpose the ethanol is distilled from the wines and relatively involved chemical procedures applied to remove i.a. water and aldehydes to prepare the ethanol for 14C determina-tion (L'ORANGE and Z1MEN 1969). The influence of these latter components on counting efficiency was investigated in an attempt to circumvent the cleaning procedure which was time-consuming_especially when many samples have tobe analysed. 1. Influence of water content of ethanol on counting ef-ficiency In Table 1 it is shown from external standard ratio values that no marked quenching occurred at water contents up to 13,3 % (v/v). However, counting ef-ficiency decreased when water contents exceeded 5 % (v/v). This decrease is re-latively small and can be ignored for all practical purposes up to water contents of 10 % (v/v) i.e., at a lcoholic strengths higher than 90 % (v/v). Table 1 Effect of water content of ethanol on counting efficiency and quenching Einfluß des Wassergehaltes von Äthanol auf Zählausbeute und Quench Water content in ethanol Counting efficiency External standard vol. •/o .,, ratio') 0 79,6 0,652 2,0 79,6 0,651 5,3 80,0 0,655 7,1 78,9 0,642 10,3 77,9 0,647 13,3 76,6 0,647 1) External standard ratio value of 0,650 ± 0,008 corresponded to a counting efficiency of 80 •/o ; all sarnples having this value and higher were regarded as unquenched. Determination of 14C in wine alcohol 169 2. 1 n f 1 u e n c e o f a c e t a 1 d e h y d e c o n t e n t o f e t h a n o 1 o n c o u n t -ing efficiency Acetaldehyde, added to ethanol in volumes from 0 to 2,0 % (v/v), showed ap-preciable quenching and counting efficiency decreases at concentrations in excess Table 2 Effect of acetaldehyde content of ethanol on counting efficiency and quenching Einfluß des Acetaldehydgehaltes von Äthanol auf Zählausbeute und Quench Aldehyde content in ethanol Counting efficiency External standard vol. •/o .,, ratio') 0 78,8 0,649 0,1 78,7 0,650 0,3 78,0 0,641 0,5 77,7 0,626 1,0 76,8 0,599 2,0 74,6 0,567 1) External standard ratio value o! 0,650 ± 0,008 corresponded to a counting efficiency of 80 'lo; all samples havlng thls value and hlgher were regarded as unquenched. of 0,5 % (v/v) (Table 2). However, acetaldehyde values of this magnitude are not obtained in ethanol from wines if a careful distillation procedure is used (L'ORANGE et ai. 1968). Consequently acetaldehydes do not affect counting efficiency under these conditions. Samples of wines were distilled by means of a 2 m long fractionating column filled with Berl saddles and a reflux ratio of approximately 1 : 8. Approximately 60 cm3 ethanol of between 92-96 % (v/v) was obtained from 750 cm3 wine. Under these conditions neither the water nor the a ldehyde content influenced the counting efficiency significantly and it was therefore not necessary to remove these com-ponents prior to 14C analysis. Literature L'ORANGB, R. und ZmeN, K. E„ 1969: Zeitliche Verteilung (1952-1967) des bei Kernwaffenversu-chen entstandenen C-14. Radiochimica Acta 11, 14(;--149. SmoN, H„ RAuscttENBAcH, P. und FRBY, A„ 1968: Unterscheidung von Gärungsalkohol und Essig von synthetischem Material durch den 14C-Gehalt. z . Lebensm.-Untersuch. u. -Forsch. 136, 279-284. Eingegangen am 2. 11. 1977 Dr. A. C. HouTMAN Oenological and Viticultural Research Institute Private Bag X5026 Stellenbosch 7600 Republic of South Africa 

The influence of acetaldehyde and water on the determination of 14C in wine alcohol

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The influence of acetaldehyde and water on the determination of 14C in wine alcohol

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