Evaluation of the Main Macro-, Micro- and Trace Elements Found in Fallopia japonica Plants and Their Traceability in Its Honey: A Case Study from the Northwestern and Western Part of Romania

Abstract

Fallopia japonica (Japanese knotweed, Reynoutria japonica or Polygonum cuspidatum) is considered an extremely invasive plant worldwide and a bioindicator of heavy metals. Yet, its potential as a crop for honeybees is still underevaluated. This study employs atomic absorption spectrometry to quantitatively analyze the concentration of macro-elements, namely, calcium (Ca), potassium (K) and magnesium (Mg); micro-elements, such as copper (Cu), iron (Fe), manganese (Mn) and selenium (Se); and trace elements, i.e., cadmium (Cd), chromium (Cr), nickel (Ni) and lead (Pb) in different anatomic parts of Fallopia japonica (FJ) plants (roots, rhizomes, stems, leaves) and their traceability into honey. This research encompasses a thorough examination of samples collected from the northwestern and western part of Romania, providing insights into their elemental composition. The results showed that the level of trace elements decreases in terms of traceability in honey samples (Pb was not detected in any of the analyzed samples, while Cd had a minimum content 0.001 mg/kg), ensuring its quality and health safety for consumption. Moreover, the data generated can function as a valuable resource to explore the plant’s positive eco-friendly impacts, particularly in relation to its honey.

Unraveling the Physicochemical, Nutritional and Antioxidant Properties of the Honey Produced from the Fallopia japonica Plant

“…The experimental sites for this study and the gathering and preparing of the samples are the same as in our previous article [26], as the study is a continuation of the research conducted by our team, focused on the FJ plant and honey and the therapeutic effects. Briefly, the study was conducted in the northwestern and western part of Romania, namely three different areas from the (1) Merișor area, Maramureș County (47°39′25.2″ N 23°24′06.7″ E), in the hydrographic confluence area of the Lapus and Somes rivers and Baia Mare depression; (2) the Valea Vinului area, Satu Mare County (47°43′46.9″ N 23°10′26.3″ E), on the Someș river meadow; and (3) the Bocsig area, Arad County (46°25′50.4″ N 21°57′47.3″ E), on the Crișul Alb river meadow [26].…”

“…The areas from which the honey was collected are highly dominated by the FJ plant, Merișor being the most affected by its invasiveness, while Bocsig area was the less-impacted experimental site from the point of view of the FJ habitat [26].…”

“…From the sites mentioned above, we were able to find a limited number of certified beekeepers who were engaged in the production and commercialization of FJH. The gathering and processing the samples were conducted in line with our previous study [26]: nine samples of FJH (three samples from each location and different apiaries) were obtained directly from local beekeepers in November 2022, two months after the honey was produced (September 2022). These samples were meticulously preserved in hermetic glass containers and maintained at a temperature of 5 °C until the analyses were conducted (Figure 1).…”

“…Given the lack of scientific literature detailing the pollen spectrum of FJH [30], it is necessary to corroborate the pollen analysis with the physicochemical parameters and sensory parameters of FJH [26,32], in order to obtain a full description of the characteristics of this honey type [51].…”

“…Although FaJ is recognized as one of the most invasive plants worldwide-particularly in riparian habitats near rivers and waterways, as in the case of Romania [26], with a large contribution to pollination services through its nectar-rich inflorescences [11,27,28] and production of over 200 kg/ha of honey [29]-there is a limited amount of research on Fallopia japonica honey (FJH). Only four studies [26,[30][31][32] have been conducted, all in Romania, but none of them fully characterize this unique type of honey.…”