The commercial cellulose fibers and cellulose fibers extracted from rice and oat husks were analyzed by chemical composition, morphology, functional groups, crystallinity and thermal properties. The cellulose fibers from rice and oat husks were used to produce hydrogels with poly (vinyl alcohol). The fibers presented different structural, crystallinity, and thermal properties, depending on the cellulose source. The hydrogel from rice cellulose fibers had a network structure with a similar agglomeration sponge, with more homogeneous pores compared to the hydrogel from oat cellulose fibers. The hydrogels prepared from the cellulose extracted from rice and oat husks showed water absorption capacity of 141.6-392.1% and high opacity. The highest water absorption capacity and maximum stress the compression were presented by rice cellulose hydrogel at 25°C. These results show that the use of agro-industrial residues is promising for the biomaterial field, especially in the preparation of hydrogels.

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There is a worldwide demand for environment‐friendly, biodegradable materials. The objective of this study is to develop biocomposite films using native or phosphorylated wheat starch reinforced with cellulose nanocrystals (CNCs) from three different sources, rice, oat, and eucalyptus husks. The films are evaluated by their morphology, thermal properties, relative crystallinity (RC), water vapor permeability (WVP), and mechanical properties. The high RC of the CNCs increases the RC of biocomposite films. The films produced using native and phosphorylated starches present higher WVP than those incorporated within CNCs. The films without CNCs also present low solubility, remain intact after 24 h of immersion in water under agitation, and resist water absorption. The CNCs incorporation increases the tensile strength of the films. Biocomposite films produced using native starch and oat CNCs yield the highest tensile strength (5.07 ± 0.33 MPa), showing a remarkable increase of 91.3% when compared to the film obtained using native starch (2.65 ± 0.09 MPa). The biocomposite films produced in this study show satisfactory mechanical properties, such as high resistance and flexibility, thereby presenting great potential for application in food industry.

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This study presents the valorization of the Gelidium sesquipedale seaweed for the development of bioactive aerogels with interest in food packaging applications. The raw seaweed was used to extract cellulose, highly crystalline (Xc∼70%) and high aspect ratio (∼40) nanocellulose and an agarbased extract, rich in polyphenols and with antioxidant capacity. Subsequently, pure PVA and hybrid aerogels containing cellulose and nanocellulose were produced by a physical cross-linking method. The presence of hydroxyl groups provided by the high aspect ratio of nanocellulose promoted the interactions with water and facilitated the accessibility of moisture towards the interior of the aerogels, hence generating high water sorption capacity materials. The agar-based extract was then incorporated into selected formulations and the release in hydrophobic and hydrophilic food simulant media was investigated. Pure PVA aerogels dissolved in aqueous media, resulting in an immediate release of the bioactive. Interestingly, the hybrid aerogels containing cellulose and nanocellulose preserved their integrity and provided a more gradual release. Although the hybrid aerogels presented similar release profiles during the first 48 h, the presence of nanocellulose led to greater release values after more prolonged times. This shows the promising properties of hybrid PVA/cellulose/nanocellulose aerogels as matrices for the controlled release of bioactive compounds in food systems, which could be of interest for the development of bioactive packaging structures.