Valorization of wheat straw in food packaging: A source of cellulose.

Wheat straw (WS) is one of the abundant categories of agricultural waste, which is usually abandoned and burned yearly, thus creating environmental issues. Traditionally, it is used for low-value purposes, mainly in cattle feeding or agricultural mulch, and the rest is burnt or thrown away. WS is a valuable candidate as raw material for being used as reinforcing fibers to fabricate biocomposites. Among existing strategies, one of the potential strategies to utilize such lignocellulosic biomasses includes the extraction of cellulose as a potential candidate in the fabrication of sustainable packaging. Exploring WS as a valuable source of cellulose could be a key strategy for enabling biopolymers in packaging, which relies on developing tailor-made materials from non-food and low-cost resources. In this regard, the valorization of WSs for packaging can add value to these underutilized residues and successfully contribute to the circular economy concept. The review addresses the valorization of WS as a source of cellulose and its nanostructured forms for food packaging applications. The review also discusses cellulose derivatives extraction using conventional or innovative techniques (microwave-assisted extraction, fractionation, mechanical fibrillation, steam-explosion, microfludization, enzymatic hydrolysis, etc.). The different applications of these extracted biopolymers in the packaging are also summarized.

Nanochitosan functionalized hydrophobic starch/guar gum biocomposite for edible coating application with improved optical, thermal, mechanical, and surface property.

The current work demonstrates a unique approach of utilizing nanochitosan (NCS) based edible nanomodifier for functionalizing starch (ST)/guar gum (GG) biocomposite with superior packaging properties targeting stringent edible food packaging on fresh cuts. The effectiveness of NCS in terms of structure-property-performance analysis of ST/GG biocomposites was done. The inclusion of NCS to the biocomposites of ST/GG converts its hydrophilic surface nature to hydrophobic (contact angle of ~114°) by modifying the surface features. The addition of NCS improved the thermal stability, where the observed 10% weight degradation of ST biocomposites were ~79.36, ~80.49, and ~186.89 °C for neat ST, ST/GG biocomposites, and ST/GG/NCS (3% w/v) (ST-GG-NCS3), respectively. The observed transparency of ST, ST-GG, and ST-GG-NCS3 were 21, 8, and 48%, respectively in the visible region suggesting consumer preference for transparent packaging materials. The wt% of O, C and N elements in ST-GG-NCS3 as observed by EDX spectra were ~ 50.2, ~47.6, and ~ 2.2%, respectively, which confirm the safety of the materials. Additionally, it is noteworthy to mention that the storage quality in terms of microbial growth, pH change, color attributes, and weight loss are better preserved when used as an edible coating on cut apple fruits.

Development of antioxidant-rich edible active films and coatings incorporated with de-oiled ethanolic green algae extract: a candidate for prolonging the shelf life of fresh produce.

The concept of sustainability and the substitution of non-biodegradable packaging using biodegradable packaging has attracted gigantic interest. The objective of the present study was to revalorize the biowaste "de-oiled green algae biomass (DAB)" of Dunaliella tertiolecta using a green approach and the development of biodegradable chitosan (CS)-based edible active biocomposite films and coatings for prolonging the shelf life of fresh produce. Ultrasound-assisted green extraction was conducted using food-grade solvent ethanol for obtaining the bio-actives, namely "crude algae ethanolic extract (CAEE)" from DAB. The edible films (CS/CAEE) and coating solutions were developed by incorporating CAEE with varying concentrations (0 to 28%). The CAEE was subjected to MALDI-TOF-MS, NMR, and other biochemical analyses, and was found to be rich in DPPH antioxidant activity (∼40%). The CS/CAEE films were fabricated using a solvent casting method and characterized by several biochemical and physicochemical (FESEM, TGA, FTIR, XRD, WVP, UTM, and rheological) characterization techniques. The addition of CAEE into the CS matrix reduced the maximum film transparency (∼20%), water vapor permeability (∼60%); improved the crystallinity (∼24%), tensile strength (∼25%), and antioxidant activity (∼27%); and exhibited UV-Vis blocking properties as compared to the control film. Besides, the developed coating solutions and CAEE showed biocompatibility with BHK-21 fibroblast cells and antimicrobial activity against common food pathogens. The developed coating solution was applied on green chilli using a dipping method and stored at ambient temperature (25 ± 2 °C, 50-70 % RH) for 10 days. The shelf life of chillies was extended without altering the quality as compared to uncoated green chillies. Therefore, the formulated coating could be applicable for prolonging the shelf life of fresh produce.

Curcumin doped functionalized cellulose nanofibers based edible chitosan coating on kiwifruits.

The developed edible coating with curcumin facilitated iron functionalized cellulose nanofiber (f-CNF) reinforced chitosan (CS) were applied on kiwifruits for maintaining the quality during storage life. The f-CNF was fabricated via anchoring iron particles onto the surface of CNF as evident by FESEM, FETEM, and XRD analysis. The inclusion of f-CNF and curcumin as a component of edible coating can provide a synergistic effect in maintaining the quality of kiwifruits. The f-CNF (1.5 wt%) dispersed CS edible coating assisted by curcumin provided a lamellar and heterogonous surface morphology with a hazy appearance. The used edible coating materials were effective in reducing mass loss, firmness loss, respiration rate, and microbial count of the kiwifruits during storage life (10 days at 10 °C). Additionally, color, and physiological properties of kiwifruits can be modified by using the addressed edible coating materials.

Silk nanodisc based edible chitosan nanocomposite coating for fresh produces: A candidate with superior thermal, hydrophobic, optical, mechanical and food properties.

This paper demonstrates the fabrication of silk nanodisc (SND) dispersed chitosan (CS) based new edible coating as a candidate for superior thermal, hydrophobic, optical, mechanical, and physicochemical properties, which further provide remarkable storage quality for banana fruits. Fabrication of SND is attained following acid hydrolysis of silk fibroin (SF), where the successful nanostructures formulations are analyzed by FESEM, FETEM and XRD analysis delivering disc shaped morphology with amplified crystallinity (~95.0%). The SF has been fabricated from waste muga cocoons using the degumming process. The superior thermal stability of SND compared to SF portray a new era in required heat resistant packaging. The effectiveness of SND is investigated on packaging properties of CS biocomposites including thermal, wettability, mechanical, color, surface morphology, and others. Wettability of SND incorporated CS biocomposite enhanced by ~ 10° suggesting improved hydrophobicity. The edible coatings are a new candidate to improve the shelf life of bananas over 7 days at 25 °C for prevailing original weight, optical property, firmness, and others.

Influence of Nontoxic Magnetic Cellulose Nanofibers on Chitosan Based Edible Nanocoating: A Candidate for Improved Mechanical, Thermal, Optical, and Texture Properties.

The present work demonstrates the formulation of cellulose nanofiber (CNF) or magnetic cellulose nanofiber (mgCNF) dispersed chitosan-based edible nanocoating with superior mechanical, thermal, optical, and texture properties. The fabrication of mgCNF is successfully achieved through a single-step coprecipitation route, where iron particles get adsorbed onto CNF. The thermal stability of mgCNF is improved considerably, where ∼17% reduction in weight is observed, whereas CNF degrades completely under identical conditions. TGA analysis shows that there is an improvement in thermal stability for both CNF- and mgCNF-reinforced CS nanocoatings, where mgCNF provides more heat dimensional stability than CNF-dispersed CS nanocoatings. Further, the edible nanocoatings are stable even at the temperature of heat treatment such as food sterilization. The mechanical property of the mgCNF-dispersed chitosan (CS) shows a remarkable improvement in tensile strength (57.86 ± 14 MPa) and Young's modulus (2348.52 ± 276 MPa) in comparison to neat CS (6.27 ± 0.7 and 462.36 ± 64 MPa, respectively). To determine the developed materials to be safe for food, the quantification of iron is made by using ICP-MS technique. It is worth mentioning that mgCNF-coated CS helps in improving the texture of cut pineapples in comparison with uncoated pineapple slices under ambient conditions.

Poly (lactic acid)/modified gum arabic (MG)based microcellular composite foam: Effect of MG on foam properties, thermal and crystallization behavior.

The article demonstrates a simple and innocuous method for fabrication of poly (lactic acid) (PLA)/modified gum arabic (MG)based hydrophobic, microcellular, highly porous and interconnected composite foam. The observed density of the composite foams was remarkably reduced by ~86% in comparison to PLA granules. Further, there was noticed an increase in cell density and a decrease in cell size due to the addition of MG nanofiller. The thermogravimetric analysis (TGA) of developed foam showed no significant effect of MG in maximum degradation temperature (Tmax). Dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) investigations suggested the plasticizing effect of MG nanofiller in the PLA matrix. The hydrophobicity of fabricated foam was found to increase with an increase in loading of MG and an increment of ~20° in contact angle was observed for highest loading of MG (3%) in comparison to neat PLA foam. Further, an increase in the surface area up to ~60% and a decrease in pore diameter up to ~53% were observed for PLA/MG based foam by porosimetric investigations. Based on this investigation, the fabricated PLA/MG based foams have the potential for specialized applications as an alternative to non-degradable petro-based foams in various fields of life.