Filtration
methods for alcoholic fermented beverages often use
filter aids such as diatomaceous earth (DE), which may contain elevated
amounts of the heavy metals arsenic (As), lead (Pb), and cadmium (Cd).
Here, we evaluated factors affecting transfer of these heavy metals
from DE to beer and wine. A laboratory-scale filtration system was
used to process unfiltered ale, lager, red wine, and white wine with
three types of food-grade DE. Filtrate and DE were analyzed for heavy
metals using ICP-MS, in addition to LC-ICP-MS for As-speciation analysis.
Use of 2 g/L DE containing 5.4 mg/kg soluble inorganic As (iAs) for
filtering beer and wine resulted in significant (p < 0.05) increases of 11.2–13.7 μg/L iAs in the filtered
beverage. There was a significant (p < 0.05) effect
from the DE quantity used in filtration on the transfer of iAs in
all beverage types, whereas no alterations were observed for Pb and
Cd levels. Methods to wash DE using water, citric acid, or EDTA all
significantly (p < 0.05) reduced iAs concentrations,
whereas only EDTA significantly reduced Pb levels. Cd concentrations
were not affected by any wash method. These data indicate that specific
steps can be taken to limit heavy-metal transfer from DE filter aids
to beer and wine.
Bureau of Alcohol, Tobacco and Firearms regulations require that a straight whiskey be aged in a freshly charred oak barrel for a minimum of 2 years and that it not be colored with added caramel. The regulations, however, permit addition of caramel in blended whiskeys. Blended whiskeys are usually produced by mixing a straight whiskey with neutral spirits which causes loss of color intensity. Caramel addition is permitted to compensate for this loss. Thus, it is not possible to authenticate the standard of identity of a straight whiskey by measurement of color intensity. Our investigations suggest that furfural (2-furaldehyde) and 5-hydroxymethyl-2-furaldehyde are imparted into a straight whiskey during aging in a freshly charred oak barrel. Caramel, on the other hand, imparts only 5-hydroxymethyl-2-furaldehyde. Thus, the measurement of the concentrations of furfural and 5-hydroxymethyl-2-furaldehyde and their ratio could effectively authenticate the standard of identity of straight whiskeys. This study shows that straight whiskeys aged in freshly charred oak barrels for a period of 2 years or more have a 2:1 or higher ratio of furfural to 5-hydroxymethyl-2-furaldehyde. A high-performance liquid chromatographic method for the determination of furfural and 5-hyroxy- methyl-2-furaldehyde at low parts-per-million levels is described.
This paper describes an analytical method for the quantitation of iron, cobalt, nickel, and copper at trace levels with graphite furnace-atomic absorption spectrometry (GF-AAS) without the use of any matrix modifier or preconcentration techniques. A solution of HfF4 (10%, w/v) in HF (24%) was used for this study. The detection limits for iron, cobalt, nickel, and copper were found to be 3, 1, 3, and 2 ppb, respectively. The average precision of measurements (% RSD) for all the elements was <10%.
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