Green biorefining uses fresh lignocellulosic biomass to produce green juice and pressed fibre fractions by wet fractionation. The latter is a byproduct, accounting for 25–32% of the starting material. In this study, the composition (glucan, xylan, arabinan, lignin, total phenol, flavonoid and protein) of pressed fibres obtained from four alfalfa, four soy and one broccoli varieties were determined at different harvest times. Statistical analyses were performed to determine the effects of harvest time and variety on the measured parameters. In most of the cases, there were interactions between the effects of harvest time and variety. Among alfalfa varieties, OLI1 had the highest carbohydrate (52.09 w/w%) and DIM3 had the lowest lignin (13.02 w/w%) content. In the case of soy, the ADV2 variety had the highest carbohydrate (53.47 w/w%) and PK1 had the lowest lignin (11.14 w/w%) content. Broccoli contained low amounts of carbohydrates (44.94 w/w%) and lignin (10.16 w/w%). The phenolic and flavonoid contents were similar for each species, but the protein content was the highest in alfalfa fibre. Based on these data, the most promising species, varieties and harvesting time can be selected in terms of a certain component that could be essential to produce functional foods with enhanced nutritional value.

The present study aimed to characterize soybean pressed fiber obtained through wet fractionation of green biomass and evaluate the effects of variety and vegetation window on its composition and valorization potential. Four soybean varieties (Advisor, Bólyi 612, Isidor, and Pannónia kincse) were investigated across two distinct vegetation windows using anatomical, cell wall, biochemical, and pigment analyses. Significant variety-dependent differences were observed in several anatomical traits related to biomass quality. Isidor exhibited the greatest leaf blade thickness, while Advisor showed favorable stem structural characteristics and enhanced cuticle development. Cell wall analysis revealed significant differences in xylan, arabinan, and Klason lignin between vegetation windows, while glucan content was affected by both variety and vegetation window, with the highest value observed in Advisor during the first vegetation window. Photosynthetic pigment composition remained relatively stable among varieties and vegetation windows. Because the two vegetation windows occurred during different calendar periods, the observed differences may reflect both plant developmental status and seasonal environmental conditions and cannot be exclusively attributed to harvest timing. This one-year exploratory study provides baseline information on soybean pressed fiber as a potential secondary biomass resource. Further multi-year and multi-environment studies are required to assess the stability and environmental consistency of these findings.