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

Abstract

Fallopia japonica (FJ), commonly known as Japanese knotweed, is now recognized as one of the most invasive plants in Europe and globally. Despite its widespread presence in Europe and its significant nectar production, there is currently limited scientific data on the unique unifloral honey derived from it. This study examines the physicochemical composition of Fallopia japonica honey (FJH) samples collected from various regions in Romania. Additionally, the nutritional and antioxidant profiles of FJH were assessed. The sensory analysis revealed a honey with a brown-caramel color and an intense flavor, characterized by fine, consistent crystals during crystallization. The results indicated that FJH has a high carbohydrate content (fructose: 35.12-40.65 g/100 g; glucose: 28.06-37.79 g/100 g); elevated electrical conductivity (387-692 µS/cm), diastase activity (9.11-17.01 DN), and acidity (21.61-42.89 meq/kg); and substantial total phenolic (89.87-120.08 mg/100 g) and flavonoid (18.13-39.38 mg/g) contents. These findings highlight FJH's favorable nutritional properties, aligning with the standard codex for honey. The antioxidant profile of FJH demonstrated strong DPPH and ferric reduction antioxidant power (FRAP) activities, comparable to those of buckwheat honey, underscoring its potential health benefits and commercial value. These results provide new insights into how this invasive plant can be harnessed as a valuable resource for sustainable beekeeping practices.

Keywords: Fallopia japonica honey; antioxidant capacity; nutritional benefits.

Figure 1

FJH samples gathered from the three experimental sites. (Source: Alexandra-Antonia Cucu personal collection).

Figure 2

FJ pollen type identified in the honey samples.

Figure 3

PC (upper) and HCA (lower) of the honey samples according to their geographic origin and melissopalynological analysis, where blue stands for Maramureș area, orange for Arad area and pink for Satu Mare area.

Figure 4

PCA representations of the FJH samples (A), and nutritional values, phenolics and antioxidant activities (B). A total of 77.2% of the overall variance was attributed to the first two dimensions (C). Discriminant analysis (PLS-DA) plot of the physicochemical parameters, and antioxidant activities of the samples according to their areas of collection (D). Ellipses reveal the points of each level of the sets of groups and represent 95% confidence intervals. The first axis explained 35.6% and the second 29.7% of the overall variance of the centroids.

Figure 5

Heatmap and cluster analysis visualization of physicochemical analysis, phenolics and antioxidant activities in FJH samples. Columns indicate the FJH samples according to their collection sites, whereas rows represent the evaluated bioactive compounds, and antioxidant activities. Based on the detected bioactivities, the cells are highlighted accordingly, where blue denotes a significant negative association and red denotes a significant positive association.