During aging, changes

The color of vinegar during aging changes from yellow/brown to brown/ black, due to the accumulation of chromophore-labeled melanoidins (Falcone and Giudici, 2008). At least four classes of melanoidins contribute to this coloration. Falcone and Giudici (2008) propose the ratio between the absorbance at 420 nm of TBV and the absorbance of the cooked must (brown index, BI) as a descriptor of the vinegar color and physical age (PRT) ... 

Fig. 10.7. The yield strength of quenched Al-4 wt% Cu changes dramatically during ageing at 1 50°C...

Adenosine A-l receptor density was examined in rat brain by means of quantitative autoradiography to obtain a detailed anatomical overview of the changes during ageing (Murillo-Rodriguez et al. 2004). A-l receptor binding was assessed in young, old, and senescent animals of 3, 24, and 30 months old, respectively. 

The procedure was proposed for the study of the change in pigment composition during ageing [237],... 

A.-St. Jaaskelainen, T. Liitia, UV/vis reflectance spectroscopy reveals the changes in fibre chemistry during ageing. Spectroscopy Europe, 19(5), 11-13 (2007). 

Bakker, J., Picinelli, A., and Bridle, P., Modell wine solutions colour and composition changes during ageing, Vitis, 32, 111, 1993. 

Ortega-Heras, M., Rivero-Perez, M. D., Perez-Magarino, S., Gonzalez-Huerta, C., and Gon-zalez-Sanjose, M. L. (2008). Changes in the volatile composition of red wines during aging in oak barrels due to microoxygenation treatment applied before malolactic fermentation. 

Typical changes in bone mineral density with time after the onset of menopause, with and without treatment. In the untreated condition, bone is lost during aging in both men and women. Fluoride, strontium (Sr2+), and parathyroid hormone (PTH) promote new bone formation and can increase bone mineral density in subjects who respond to it throughout the period of treatment, although PTH also activates bone resorption. In contrast, estrogen, calcitonin, and bisphosphonates block bone resorption. This leads to a transient increase in bone mineral density because bone formation is not initially decreased. However, with time, both bone formation and bone resorption are decreased with these pure antiresorptive agents, and bone mineral density reaches a new plateau. 

Finally, we try to develop a chemical interpretation for the color of red wine—i.e., the specific role of different substances and the changes they undergo which cause the evolution of wine color, especially during aging. 

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