Selective lignin depolymerization (SLD) has emerged as a value-added method of pretreatment for lignocellulosic biorefining, in which lignin is depolymerized into valuable phenolic monomers prior to utilization of the hemicellulose and cellulose. Herein, we report a biomimetic Fenton catalyzed SLD process, converting sweet sorghum bagasse into an organic oil that is rich in phenolic monomers and a solid carbohydrate that is favorable for enzymatic hydrolysis into sugars. Initially, the feedstock's molecular structure was modified through iron chelation and free radical oxidation via Fenton's reagent (Fe 3+ , H 2 O 2 ). The lignin component of the modified feedstock was then selectively depolymerized in supercritical ethanol (250 °C, 6.5 MPa) under nitrogen to produce a phenolic oil, with a maximum yield of 75.8 wt %. Six valuable phenolic monomers were detected in this oil, with a maximum cumulative yield of 19.1 wt %. The solid carbohydrate obtained after the SLD process was enzymatically hydrolyzed to liberate 62.7 and 79.9 wt % of the initial 5-and 6-carbon polysaccharides within 24 h, respectively, indicating the majority of the hemicellulose and cellulose were preserved during the SLD process. Fenton modification not only increased the yields of phenolic monomers, particularly ethyl-p-coumarate and ethyl-ferulate, but also enhanced enzymatic hydrolysis.
Large amounts of food are wasted during the food supply chain.
This loss is in part due to consumer confusion over dates on food
packages that can indicate a variety of quality indicators in the
product (e.g., expiration date, “best by” date, “sell
by” dates, etc.). To reduce this food loss, much research has
been focused on the films that offer simple and easily manipulated
indication systems to detect food spoilage. However, these materials
are usually hydrophilic biopolymers that can detect the food spoilage
in a wide pH range but do not provide highly sensitive real-time measurements.
In this work, a glycerol-based nanocomposite core–shell latex
film was synthesized to create a responsive packaging material that
can provide real-time pH detection of food with high sensitivity.
First, the pH-responsive dendrimer comonomer was synthesized from
glycerol and diamine. Then, the nanoencapsulation polymerization process
via miniemulsion was conducted to form a core–shell structure
with tunable nanoshell thickness for a sensible pH-responsive release
(<0.5 pH change). Next, the flexible film encapsulated a color-indicative
dye that provided highly sensitive and visible color changes as both
the pH dropped and the time elapsed in the food. This film also provided
a barrier to water and heat and resisted deformation. Ultimately,
this nanocomposite flexible film pending a pH sensor has the potential
as an intelligent food packaging material for a universal, accurate,
easy-to-use, and real-time food spoilage monitoring system to reduce
food waste.
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