Total and Free Sulfite Assay Kit (Liquid Ready)

The presence of potentially hazardous substances in fruit wines poses a threat for human health. However, the management standards and specifications of hazardous substances contained within various types of fruit wines are currently insufficient. The aim of this study was to analyze hazardous substances (cyanide, acetaldehyde, and ethyl carbamate) and quality control characteristics (pH, titratable acidity, sulfur dioxide, and diacetyl) in seven different types of fruit wines. The pH levels and titratable acidity varied between fruit wine types. In all fruit wines, sulfur dioxide (SO₂) was within acceptable ranges as per the Korean standard. Acetaldehyde content also varied between fruit wine types as well as based on the analytical method (titration or enzymatic analysis) employed. Cyanide was in the range of 0.02-0.35 mg/L. Diacetyl contents were in the range of 0.66–2.95 mg/L (p > 0.05). The contents of ethyl carbamate varied considerably, within the range of 5.22–259.69 μg/kg (p < 0.05). The analytical methods of diacetyl and ethyl carbamate were validated for specificity, linearity, sensitivity, accuracy, and precision. Therefore, the content of hazardous substances and quality control characteristics should be closely monitored and controlled to improve safety and quality of the traditional fruit wines.

Microoxygenation (MOX) is used to improve wine colour and sensory quality; however, limited information is available for Pinot noir wines and wines with different initial phenolic content. In this study, MOX was applied to two Pinot noir wines, with either a low or a high phenolic content, at two doses (0.50 and 2.11 mg/L/day) for 14 days. With the sterile filtration applied, acetaldehyde formation during MOX was very low, supporting the influence of yeast on acetaldehyde production during MOX. The MOX dosage rate did not significantly affect colour development, while the Pinot noir wine with higher phenolics benefited more from MOX, significantly increasing colour intensity and SO₂ resistant (polymeric) pigments. However, these changes did not guarantee colour stability, as a final SO₂ addition (100 mg/L) largely erased the improvement to colour in all wines. This could be due to the lower acetaldehyde formation, thus less ethyl-bridged stable pigments resistant to SO₂ bleaching. MOX also decreased the flavan-3-ols and anthocyanin monomers, which differed between the two Pinot noir wines, reflecting the initial phenolic content. Lastly, MOX generally increased the measured tannin concentration and affected the proportion of tannin subunits, with a decrease in tannin mass conversion and proportion of (-)-epigallocatechin extension units. Some of these changes in phenolic compounds could potentially increase astringency, suggesting that MOX should be applied to Pinot noir and other low phenolic wines with caution.