Abstract
This work proposes a biorefinery approach for the utilization of agri-food residues, such as tomato pomace (TP), through combining chemical hydrolysis with high-pressure homogenization (HPH), aiming to achieve the isolation of cellulose with tailored morphological properties from underused lignocellulose feedstocks, along with the valorization of the value-added compounds contained in the biomass. Cellulose was isolated from TP using sequential chemical hydrolysis in combination with mechanical pretreatment through HPH. The chemical and structural features of cellulose isolated from TP pretreated by HPH were compared with cellulose isolated from untreated TP through light scattering for particle size distribution, optical and scanning electron microscopy, and Fourier-transform infrared spectroscopy (FT-IR) analysis. HPH pretreatment (80 MPa, 10 passes) not only promoted a slight increase in the yield of cellulose extraction (+9%) but contributed to directly obtaining defibrillated cellulose particles, characterized by smaller irregular domains containing elongated needle-like fibers. Moreover, the selected mild chemical process produced side streams rich in bioactive molecules, evaluated in terms of total phenols and reducing activity. The liquors recovered from acid hydrolysis of TP exhibited a higher biological activity than those obtained through a conventional extraction (80% v/v acetone, 25 °C, 24 h at 180 rpm).
Highlights
In recent years, cellulose has received increasing interest as a renewable raw material for producing biodegradable polymeric products and contributing to replacing fossil resources, considering their depletion, fluctuation in oil prices, and the negative environmental impacts [1]
0.10 mgGAE /gDM for tomato pomace (TP) and high-pressure homogenization (HPH)-TP, respectively, were obtained in the liquor from acid hydrolysis. These findings suggest that the side streams of the lignocellulosic fractionation process can be exploited to efficiently recover phenolic compounds, replacing the conventionally applied solvent extraction step, contributing to enhancing the sustainability and economic viability of the cellulose recovery process from agri-food residues
The present work shows for the first time that tomato pomace residues represent a viable and sustainable lignocellulosic source for cellulose isolation
Summary
Cellulose has received increasing interest as a renewable raw material for producing biodegradable polymeric products and contributing to replacing fossil resources, considering their depletion, fluctuation in oil prices, and the negative environmental impacts [1]. Research has primarily focused on the production of cellulose from lignocellulosic waste, such as coconut husk fibers [3], cassava bagasse [4], hazelnut shells [5], rice husk [6,7,8], wheat straw [9,10,11], oat hull [12], and okara [13,14] All these biomasses mainly consist of three natural organic polymers, cellulose, hemicellulose, and lignin, and contain small amounts of proteins, pectin, and other extractives (e.g., bioactive molecules). Available data show intrinsic limitations in the cellulose extraction that can be obtained: lower acid concentrations are reported to produce particles characterized by highly amorphous regions with low crystallinity, reducing the yield and purity of cellulose [28]
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