a b s t r a c tAnnona cherimola Mill. seeds are a residue of the industrial processing of this fruit, for which, presently, there is no industrial application. They have a considerable amount of oil, which can be converted into biodiesel, but the remaining lignocellulosic fraction still needs relevant added-value valorization routes.In this work, the selective hemicelluloses removal by autohydrolysis was optimized aiming to maximize the yield of oligosaccharides with potential applications in food, pharmaceutical and cosmetic industries. A maximum of 10.4 g L −1 of oligosaccharides was obtained, for a severity factor of 3.6, where 74.5% of the original hemicellulose was solubilized.The process kinetics is presented, modeled (based on the Arrhenius equation) and its scale-up is discussed. The hydrolyzate shelf-life was evaluated and the produced oligosaccharides are stable at room temperature for, at least, 3 weeks. Furthermore, all oligosaccharides are also stable at 100• C for 1 h, in pH values between 1 and 11, enabling their industrial processing, and at 37• C for 3 h, in pH values between 1 and 3, thus indicating its potential classification as non-digestible oligosaccharides. The remaining cellulose enriched solids presented an increased enzymatic digestibility (as a function of the autohydrolysis severity) that assures its efficient use in subsequent processes (e.g., bioethanol production).The upgrade route developed in this work in combination to the previously reported use of A. cherimola seed oil for biodiesel production can lead to an integrated zero-waste valorization strategy within the biorefinery framework.

Pinus pinea nuts are commercial relevant Mediterranean edible forest nuts, with an increasing production and market value, whose industrial processing yields a lignocellulosic by-product, the pine nut shells, currently only used for combustion. Little research has been done on pine nut shells that could support a value-added application for this residue. This work studies for the first time the production of oligosaccharides by autohydrosis, and aims at an integrated upgrade within the biorefinery framework. Autohydrolysis was explored in the temperature range between 150 and 230 °C (corresponding to severity factors 2.13–4.63). Oligosaccharides, mainly xylo-oligosaccharides (95% of the total), were the key soluble products, reaching 28.7 g/100 g of xylan of the feedstock at the optimal conditions (log R0 4.01). Other products were monosaccharides and phenolic compounds that reached 7.8 and 4.7 g/L, respectively, under the most severe conditions. The stability of the oligosaccharides at different temperatures (room, 37 °C and 100 °C) and pH (between 1 and 11) grant them significant market potential in the food and pharma sectors. The pre-treated pine nut shells by autohydrolysis presented an improved, although low, enzymatic digestibility (14%), and an improved high-heating value, therefore advising their further valorization by thermochemical pathways.

Pinus pinea nuts are commercial relevant Mediterranean edible forest nuts, whose industrial processing yields a lignocellulosic by-product, the shells (PNS), currently only used for combustion. This work aims at its integrated upgrade within the biorefinery framework. Autohydrolysis was explored in the temperature range between 150 and 230 ºC (corresponding to severity factors 2.13–4.63). Oligosaccharides, mainly xylo-oligosaccharides (95% of the total), were the key soluble products, reaching 28.74 g/100 g of xylan of the feedstock at the optimal conditions (log R0 4.01). Other products were monosaccharides and phenolic compounds, that reached 7.8 and 4.7 g/L, respectively, under the most severe conditions. The stability of the oligosaccharides at room temperature, 37º and 100°C and in the pH range between 1 and 11, grant them significant market potential in the food and pharma sectors. Pre-treated PNS presented an improved, but yet low, enzymatic digestibility (14%), and an improved high-heating value.