137 Cs Analysis by Gamma Spectrometry and Its Potential for Dating Portuguese Old Wines

Analytical methods for dating wines often involve assessments of anthropogenic 14 C, 137 Cs, and cosmogenic 14 C. Having in mind the commercial and historical significance of rare and aged wines, this study focuses on noninvasive and nondestructive 137 Cs detection. The approach relies on measuring gamma-emitting radionuclides within the energy range of 46.5–1836 keV using Hyper Pure Germanium (HPGe) detectors, specifically calibrated for horizontally positioned sealed wine bottles. The 137 Cs dating method was optimized to achieve low detection limits and was validated for accuracy. All the activities were normalized to the same arbitrary date, and each sample was measured twice. For the first time, Portuguese fortified and nonfortified wines were analyzed for 137 Cs content. Wines from the 1960–1965 vintages exhibited 137 Cs levels between 0.51 Bq/L and 1.74 Bq/L, varying by wine region and type. Fortified wines consistently showed lower 137 Cs levels than nonfortified wines, likely due to differences in the production process. The method is particularly effective for distinguishing wines produced around the 1963 bomb peak and a few subsequent years, though further research is needed to expand its applicability to other periods.