Optimised extraction and encapsulation-based stabilisation of chlorophyll from conifer needles for use as a food colourant

Abstract Forestry residues such as conifer needles represent an abundant yet underutilised source of chlorophyll, but efficient recovery and stabilisation are required for their use as natural colourants. This study evaluated chlorophyll extraction from Picea abies and Pinus sylvestris needles using ultrasound-assisted extraction (UAE), maceration, and Soxhlet extraction with different solvent systems. Fresh spruce needles yielded the highest chlorophyll-a concentrations, and UAE with acetone was identified as the most efficient method. Process optimisation using response surface methodology showed that biomass-to-solvent ratio was the dominant factor influencing chlorophyll yield, with high sample loading reducing extraction efficiency. Extracts obtained under optimised conditions were encapsulated in maltodextrin and inulin and incorporated into yoghurt to assess colour stability. Refrigerated storage (4 °C) effectively limited colour changes, whereas storage at 21 °C caused pronounced pigment degradation regardless of the carrier. These results demonstrate the potential of conifer needle biomass as a source of chlorophyll for food applications.