Valorization of Pine Nut Industry Residues on a Biorefinery Concept

Pine nut industry residues, scales and core from pinecones and shells from the nuts from Pinus pinea were fully characterized. The anatomical sections showed differences between the residues. The scales presented vascular bundles with thick tracheids and narrow lumens in the xylem. The core structure presents xylem, phloem, and sclerenchyma tissues, mainly sclereids with polylamellated walls with different wall thicknesses, shapes and sizes. Nutshells presented a thickened epidermis followed by a large portion of sclereids. The chemical composition of scales and core were similar. Scales presented 0.8% ash content, 5.7% total extractives, 35.8% total lignin, and 56.8% in polysaccharides. Core showed slightly lower cell lignification (31.6% of total lignin) and higher monosaccharides content (60.1%), with 5.5% and 1.7% extractives and ashes. Nutshells had a higher lignin content (49.5%), lower content of monosaccharides (41.8%) and similar values of extractives (6.0%) and ash (1.6%). Lignin monomeric composition was similar, with a H/G ratio of 0.066 (scales), 0.039 (core) and 0.070 (nutshells). The ethanolic extracts presented low to moderate antioxidant activities in FRAP and DPPH methods. Thermal properties of the three residues were very similar; on average, the residues presented 77.1% of total volatiles, 21.9% of fixed carbon and 0.9% of ashes. [GRAPHICS]