Comparative quality assessment of the spring and autumn – harvest spruce sprouts

Spruce sprouts of Norway spruce (Picea Abies (L.) H. Karst) develop in early spring and late autumn. However, information on quality in these stages remains limited. This study aimed to evaluate the physical and biochemical properties of spruce sprouts harvested in May (FS-S) and in September (FS-A). To assess their quality, moisture, pH, titratable acidity, colour, vitamin C, total chlorophyll, total carotenoids, total phenolic compounds, flavonoids, tannin content, antiradical activity and antioxidant capacity, as well as microbiological parameters and volatile compounds, were evaluated. The FS-A sample exhibited a significantly higher pH (4.25 ± 0.01) compared with the FS-S sample (3.10 ± 0.05). In contrast, most bioactive compounds were present at higher levels in the FS-S than in FS-A. Vitamin C content was almost two times higher in FS-S (915.56 ± 0.05 mg 100 g⁻¹ FW) compared to FS-A (505.55 ± 0.05 mg 100 g⁻¹ FW). Total chlorophyll content was 15 times higher in FS-S (95.14 ± 12.12 mg 100 g⁻¹ DW) compared to FS-A (6.19 ± 0.78 mg 100 g⁻¹ FW); however, chlorophyll was greater in FS-A, likely due to the higher pH value. FS-S showed slightly higher total microbial, yeast, and mould counts, while Escherichia coli and Salmonella spp. were not detected in any samples. Volatile compound analysis revealed a higher proportion of D-limonene in FS-S (35.56%), contributing to the citrusy aroma, whereas FS-A was characterised by fenchene (14.81%) and D-limonene (14.57%). Overall, spring-harvest spruce sprouts exhibited a higher bioactive compound content, supporting their potential as a functional and sustainable food ingredient.