To address the detrimental effects of non-biodegradable wastes on the environment and the health of living organisms, there is a growing interest in valorising renewable resources. Lignocellulosic biomass is an abundant and renewable resource from plants. It is non-toxic, biodegradable and has adjustable mechanical characteristics, making it promising for use in the manufacture of hydrogels. Hydrogels are insoluble water absorbents with a three-dimensional network structure that can hold a considerable amount of water. The production of hydrogels from lignocellulosic biomass is a step toward sustainability. The goal of this study is to highlight current methodologies for the synthesis of hydrogels from various lignocellulosic biomass polymers (cellulose, hemicelluloses and lignin) in their different forms. A variety of techniques have been developed to synthesise various types of hydrogels with specified qualities, such as compressive strength, solvent resistance, water holding capacity, tensile strength, and re-swelling ratios, among others, based on application requirements. The study reports on current methods for the synthesis of lignocellulosic biomass-based hydrogels in order to determine the optimum strategy depending on demand.

Summary The present study involved valorisation of rice straw by conversion of its constituent polymer xylan and chemically modified xylans into biofilms. Hemicellulosic xylan (19.94%) extracted with 10% NaOH (85 °C, 2.6 h) was chemically modified to acetylated (AX) and carboxymethylated xylan (CMX). Biofilms were prepared by reaction of xylan/modified xylan (1% and 2%) with polyvinyl alcohol using eco‐friendly and cheap cross‐linker citric acid and glycerol as plasticiser. 2% xylan biofilms showed maximum inhibition (94.25%) of DPPH at 4 mg mL−1 which was due to large number of free ‐OH groups (highest intensity of ‐OH absorption bands in FT‐IR spectra). 2% CMX biofilms exhibited maximum antibacterial effectiveness with diameter of zone of inhibition 33.5 and 30.5 mm against Bacillus subtilis and Pseudomonas sp., respectively. This may be due to large number of undissociated COO− ions (citric acid) in CMX biofilms which was evident from lesser cross‐linking observed in their SEM images. 2% CMX biofilms also showed the highest biodegradation (86.5%) which may be attributed to formation of ether bonds along with ester bonds leading to their fast degradation. Owing to good bioactive properties of prepared biofilms, it was concluded that these can be appropriate material for food packaging by replacing synthetic plastics.

Maize (Zea mays L.) is the queen of cereals and is the third largest produced and consumed grain in the world, after rice and wheat. Scientific studies have concentrated on pigmented maize in recent decades, and breeding procedures have been identified to raise the anthocyanin content in unpigmented types using alternative strategies. Pigmented (pink, red, purple, blue, and black) maize has attracted much attention for its health-beneficial properties, mainly due to bioactive compounds such as anthocyanins, and its carotenoid composition, which are also responsible for its pigmentation. The pigmentation of maize is also attributed to the prevalence of many secondary metabolites such as polyphenolics, carotenoids, and flavonoids. Maize cells have a wide variety of pigments, ranging from yellow-orange to dark purple-blue, as well as white and creamy pigments, caused by the different expressions of these pigments. Pigments are located in the dense pericarp or aleurone regions of the kernels. Processing of pigmented maize such as nixtamalization, cooking, baking, germination, extrusion, etc. to prepare various foods significantly modulated its bioactive compounds, anthocyanin content, and antioxidant activities. The utilization of pigmented maize in different products not only enhances their nutritional and bioactive potential, but also helps to regulate starch digestibility by increasing the contents of slowly digestible starch and resistant starch, thus lowering the glycemic index of the products.

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The present study involved valorization of rice straw via production of biopolymeric films loaded with lignin and evaluation of their physical, mechanical, structural, antioxidant, antibacterial and biodegradable properties. Lignin (0.1%, 0.2% and 0.3%) loaded films were prepared by solvent casting method involving successful crosslinking between PVA, citric acid and lignin which was confirmed by ester bond formation at 1710 cm −1 in Fourier transform infrared spectrum. Scanning electron micrographs showed smooth surface in control and wavy surface in lignin film with no cracks. Lignin films possessed thickness, tensile strength and elongation at break in the range 0.127-0.142 mm, 22-31.38 MPa and 11.83-17.63%, respectively. Lightness value of films decreased while yellowness index increased as the level of lignin increased in films. Lignin loaded films showed potential antioxidant activity (51.4-74.6%) and antibacterial efficacy against Pseudomonas (diameter of inhibition zone 4.1 cm), thus suggesting their role in prevention of bacterial food contamination and organoleptic changes in food. The biodegradability tests showed that weight loss experienced by films after burial in soil was above 78.7% which offers a great advantage of these biopolymeric films over non-biodegradable synthetic plastics, hence, these may be explored further as bioplastics to replace plastic wraps in food packaging.