From Food Waste to Functional Biopolymers: Characterization of Chitin and Chitosan Produced from Prepupae of Black Soldier Fly Reared with Different Food Waste-Based Diets

The use of food waste as a rearing substrate to grow insects is an ecofriendly and sustainable alternative to food waste disposal. In the present research, Hermetia illucens prepupae were reared with a standard diet, different food waste-based diets based on vegetables, fruits, and meat, and a mixed one, where the previous three components were present equally. The demineralization and deproteination of the prepupae allowed for the obtainment of chitin that was then deacetylated to produce chitosan. Also, the bleaching of chitosan was attempted for further purification. The yield of the different reactions was investigated, and the infrared spectra of the obtained materials were analyzed to obtain information on the quantity and acetylation degree trend of the chitin and chitosan as a function of the diet. The possibility to slightly modulate the yield and acetylation degree of both biopolymers thanks to the specific diet was enlightened. Interestingly, the standard diet resulted in the highest fraction of chitin having the highest acetylation degree, and in the highest fraction of chitosan having the lowest acetylation degree.

Macrophage polarization in vitro and in vivo modified by contact with fragmented chitosan hydrogel

We have previously shown that implantation of a fragmented chitosan hydrogel suspension (chitosan-FPHS) into a traumatic spinal cord lesion in adult rats led to significant axon regrowth and functional recovery, which was associated to a modulation of inflammation. Using an in vitro culture system, we show here that polarization of bone marrow-derived macrophages is indeed modified by direct contact with chitosan-FPHS. Reducing the degree of acetylation (DA) and raising the concentration of chitosan (Cp, from 1.5% to 3%), favors macrophage polarization toward anti-inflammatory subtypes. These latter also migrate and adhere efficiently on low, but not high DA chitosan-FPHS, both in vitro and in vivo, while inflammatory macrophages rarely invade a chitosan-FPHS implant in vivo, no matter the DA. Our in vitro model setup should prove a valuable tool for screening diverse biomaterial formulations and combinations thereof for their inflammatory potential prior to implantation in vivo.

Simple and validated quantitative ¹H NMR method for the determination of methylation, acetylation, and feruloylation degree of pectin

The knowledge of pectin esterification degree is of primary importance to predict gelling and other properties of pectin from different sources. This paper reports the development of a simple and rapid (1)H NMR-based method for the simultaneous quantitative determination of methylation, acetylation, and feruloylation degree of pectin isolated from various food sources. Pectin esters are hydrolyzed in NaOH/D2O, and the obtained methanol, acetic acid, and ferulic acid are directly measured by (1)H NMR. High accuracy, repeatability, and reproducibility of the method were obtained, and the analysis time is reduced as compared to conventional chromatography- or titration-based methods.