The classification of color is important in the management and evaluation of red wine color. Nevertheless, current reports have not given a sound solution. A novel scheme for the quantitative classification of red wine color from the perspective of micro and macro levels was proposed in this work. The overall color performance of 119 representative red wine samples was visualized and classified into 125 micro-classifications according to the partition of the chromaticity and lightness of the wine color. Considering the evolution of red wine color, quantitative macro-classification of the color of the wine samples was explored, and six macro-classifications were obtained. These few classifications determine the extent of aging and aging potential of colors between different red wines well. The performance of this approach was further verified by another set of 56 red wine samples. This efficient and easy-to-implement approach is expected to be helpful in the digital and visual color management, control, evaluation, comparison, and prediction of red wines.Keywords:wine color classification;wine color evolution;CIELAB;visual representation
Caiyun Liu,Xibu Wei,Zengshuai Zhang,Qianqian Miao,Mario Prejanò,Tiziana Marino,Yongsheng Tao,Yunkui Li
The effect of pre-fermentation single additions of four cyclodextrins (CDs) as stabilizing factors on the color, aroma, and sensory characteristics of red wines was systematically investigated for the first time and compared with control and single polysaccharide treatments. The results showed that α-cyclodextrin (α-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) increased red-green color channel ( a ⁎ ) by 41.85 % and 28.84 %, respectively, compared to the control group, exhibiting a stronger copigmentation effect than the three polysaccharides. Mantel test and heatmap analyses revealed that α-CD enhanced color stability by promoting copigmentation between phenolics and monomeric anthocyanins, whereas HP-β-CD enhanced color through direct copigmentation with anthocyanins. Furthermore, volatile compound content and principal component analysis demonstrated that α-CD and HP-β-CD effectively protected esters and selectively protected alcohols, compared to the control and polysaccharide treatments. Sensory evaluation confirmed that HP-β-CD and α-CD improved the sensory profile by enhancing color appeal, rich floral and fruity aromas, and harmonious taste.
In order to explore the effects of ultrasound on the formation of acetaldehyde and its mechanism in model wine solutions, ultrasound conditions and free radicals were investigated by response surface methodology and electron paramagnetic resonance spectroscopy (EPR), respectively. The results indicate that ultrasound does induce the production of acetaldehyde with the maximum amount under the conditions of ultrasound power density 0.2 W/cm 2 , 48 min and 32 °C. The hydroxyl radicals and the 1-hydroxyethyl free radicals are the main initiator and precursor for acetaldehyde, respectively. Furthermore, the stronger the 1-hydroxyethyl free radicals captured by EPR, the lower the formation of acetaldehyde. In addition, the content of Fe 2+ and ethanol also exerted a certain influence on the acetaldehyde formation. In conclusion, ultrasound does promote the production of acetaldehyde in the model wine solutions, which is beneficial for well understanding the mechanism of ultrasound in modifying the wine color and accelerating ageing.
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