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Pineapple and hericium erinaceus (HE) produce a lot of residues in the process of food processing. These processed residues are good potential derivative precursors. In this investigation, a simple and non-toxic method was developed to prepare one new composite hydrogel by the Schiff base reaction between the aldehyde group of oxidized hydroxyethyl cellulose (OHEC) from processed pineapple peel residue and the amino group of carboxymethyl chitosan (CMCS) from processed HE residue. Subsequently, a series of experiments toward these new hydrogel polymers including structure characterization and performances were applied. The resultant hydrogel polymers were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy and confirmed with thermogravimetry. It was observed that the modification of cellulose and chitin was adequate, and the synthesis of OHEC/CMCS hydrogel polymers was successful. The gelation time experiments indicated that the shortest gel time was 33 s at a mass ratio of 4:6 (OHEC-70:CMCS). The hydrogel showed good swelling properties. The maximum swelling rate reached 11.58 g/g, and the swelling rate decreased with the increase of the oxidation degree of OHEC. The drug delivery applications of the prepared hydrogel were evaluated with bovine serum albumin (BSA) as a model drug releasing in vitro. It was discovered that the BSA release from the hydrogel was pH sensitive under simulated gastrointestinal conditions. All of these attributes indicate that the novel prepared hydrogel polymers have the potential as good carriers for oral delivery of protein-type drugs.

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Use of by-product waste from farm products to prepare clinical dressings is a resource-saving and eco-friendly approach. In this research, a series of pH-sensitive hydrogels composited with oxidized microcrystalline celluloseisolated from pineapple peel, quaternized chitosan isolated from hericium erinaceus residue and gelatin were prepared based on Schiff-base reaction.The structures of the prepared hydrogels were characterized by FT-IR, XRD and SEM, the absorption peak at around 1656 cm− 1 (due to –C = N–) and the disappeared peak at 1726 cm− 1(due to –CHO) in composite hydrogel confirmed Schiff-base reaction occurred. XRD and SEM results showed the composite hydrogels have good compatibility and well-cross linked. A series of experiments were performed to investigate the blood clotting activity and physicochemical property. It was found that the composite hydrogels can make shrink and expansion behaviors in different pH environments, and exhibited adjustable in swelling ability (up to 4383%), water evaporation rate, gel time and mechanical property as change of gelatin content. The oxidized microcrystalline cellulose/quaternized chitosan/gelatin (OMQCS-G) hydrogel showed well coagulation effect and controlled release of the loaded naringin, naringin release of OMQCS-G5 reached more than 70% within initial 6 hours, suggesting the potential of the prepared hydrogel used as wound dressing.