Determination of Three Alcohols in Chinese Dukang Base Liquor by FT-NIR Spectroscopy

Carbonyl flavor compound-targeted colorimetric sensor array based on silver nitrate and o-phenylenediamine derivatives for the discrimination of Chinese Baijiu

Baijiu is a distilled liquor of great importance in the food industry. Various aroma types, brands, and grades of Baijiu have filled the market; thus, discrimination for quality control is required. Herein, we constructed a novel colorimetric sensor array based on the redox reaction between silver nitrate and o-phenylenediamine or its derivatives for the discrimination of carbonyl flavor compounds (CFCs) and Baijius. The specific colored products were changed by CFCs depending on the influence of silver nanoparticle aggregation and chemical reactions. The array was used to qualitatively and quantitatively identify 21 CFCs with fast response (<14 min), wide linear range (0.025-25 mmol/L), and low detection limits (<60 μmol/L, 29 nmol/L for carboxylic acids). Finally, the array was successfully applied to the discrimination of 56 Baijius. The method proposed in this study is simple, fast, reliable, and has good application potential for the visual determination of Chinese Baijiu.

Furfural and organic acid targeted carbon dot sensor array for the accurate identification of Chinese baijiu

Baijiu quality control has always been a major challenge for researchers. In this paper, taking furfural which is closely related to baijiu brewing process and organic acids related to baijiu fermentation process and microorganism types as the main discriminating factors, a carbon dot (CDs) sensor array targeting furfural and organic acids was constructed to identify 41 kinds of baijiu. Through the fluorescence response investigation of CDs synthesized by isomers of benzenediol, aminophenol, and phenylenediamine to different baijiu, two CDs synthesized by meta-benzene substitutions containing -NH₂ were selected to build a fluorescence sensor array. Due to the aggregation-induced enhancement effect between furfural and the CDs, and the protonation of organic acid and the CDs, different fluorescence changes were observed, the sensor array combined with partial least squares regression could quantitatively analyze furfural and organic acids. What is more, semi-quantitative analysis of furfural and lactic acid in baijiu was performed. Owing to the interaction of the two CDs with furfural and organic acids in baijiu, the sensor array could accurately identify different baijiu through linear discriminant analysis. This sensor array has potential applications in the quantitative analysis of flavor substances in other alcoholic beverages, moreover, this method could provide a quick response and practical tool for real-time quality control monitoring in the baijiu industry.

Four-channel fluorescent sensor array based on various functionalized CdTe quantum dots for the discrimination of Chinese baijiu

As a special carrier of traditional Chinese culture, baijiu is rich in terms of types and ingredients. Its quality analysis and control are always important and complex issues that urgently need reliable evaluation methods. In this study, four different modified CdTe quantum dots (QDs) were used to characterize their sensing performance to various baijiu. A sensor array was then constructed through the complementary properties of differential fluorescence signals. To achieve an accurate and rapid evaluation of different baijiu types, a linear discriminant analysis (LDA) was introduced to extract and process spectral information. And the array was able to distinguish commercial baijiu samples with different aroma-types, brands, qualities and storage years with a recognition rate of 100%. In addition, according to the heat map, the organic acids in baijiu were shown to be the main components causing the fluorescence change through electron transfer (hydrogen bond) and resonance energy transfer among QDs and acids. Furthermore, using the partial least squares regression (PLSR) model, five representative organic acids were accurately quantified with a quantitative range of 10 μmol/L-80 μmol/L with a high selectivity. This QDs fluorescence sensing strategy provides an accurate, simple, and fast baijiu sensing method, which provides a potential use for on-line baijiu monitoring.

Quality assessment of Chinese liquor with different ages and prediction analysis based on gas chromatography and electronic nose

The economic value of Chinese liquor is closely related with its age. Results from gas chromatograph (GC) analysis indicated that 8 dominant compounds were decreased with the increase of liquor age (0 to 5 years) while ethyl lactate was found to be the most stable dominant compound as no significant change was observed in it during the aging process. Liquor groups with different ages were well-discriminated by principal component analysis (PCA) based on electronic nose signals. High-accurate identification of liquor ages was realized using linear discriminant analysis (LDA) with the accuracy of 98.3% of the total 120 samples from six age groups. Partial least squares regression (PLSR) exhibited satisfying ability for liquor age prediction (R²: 0.9732 in calibration set and 0.9101 in validation set). The feasibility of volatile compounds prediction using PLSR combined with electronic nose was also verified by this research. However, the accuracies of PLSR models can be further promoted in future researches, perhaps by using more suitable sensors or modeling approaches.