Liquid and Pressure-Sensitive Adhesives Based on Cassava Starch and Gelatin Capsule Residue: Green Alternatives for the Packaging Industry.

Natural polymer-based adhesives are green alternatives, necessary to reduce the problems impacted by synthetic adhesives. Starch and gelatin have extraordinary potential for the synthesis of biobased adhesives. Citric acid (CA), a natural acid, induces the crosslinking and hydrolyzing of both gelatin and starch. In this sense, this work deals with the use of gelatin capsule residues as a promising material to produce biobased adhesives in combination with cassava starch in the presence of different CA concentrations characterizing their mechanical, physicochemical and microstructural properties. Depending on CA concentration, formulations adjusted to different applications can be obtained such as liquid and pressure-sensitive adhesive films. The inclusion of CA allows us not only to improve the applicability of the system since it modifies the flowability of the adhesives as evidenced by the observed changes in the viscosity (from 158.3 to 90.3 for formulations with 20 and 80% CA, respectively). In addition, mechanical profiles showed that the inclusion of CA increased the adhesive bond strength (from 2230.7 to 2638.7 for formulations with 20 and 80% CA, respectively). Structural modifications induced by CA in adhesive formulations were highlighted by ATR-FTIR analysis.

Sustainable and Bio-Based Food Packaging: A Review on Past and Current Design Innovations.

Food loss and waste occur for many reasons, from crop processing to household leftovers. Even though some waste generation is unavoidable, a considerable amount is due to supply chain inefficiencies and damage during transport and handling. Packaging design and materials innovations represent real opportunities to reduce food waste within the supply chain. Besides, changes in people's lifestyles have increased the demand for high-quality, fresh, minimally processed, and ready-to-eat food products with extended shelf-life, that need to meet strict and constantly renewed food safety regulations. In this regard, accurate monitoring of food quality and spoilage is necessary to diminish both health hazards and food waste. Thus, this work provides an overview of the most recent advances in the investigation and development of food packaging materials and design with the aim to improve food chain sustainability. Enhanced barrier and surface properties as well as active materials for food conservation are reviewed. Likewise, the function, importance, current availability, and future trends of intelligent and smart packaging systems are presented, especially considering biobased sensor development by 3D printing technology. In addition, driving factors affecting fully biobased packaging design and materials development and production are discussed, considering byproducts and waste minimization and revalorization, recyclability, biodegradability, and other possible ends-of-life and their impact on product/package system sustainability.

Sustainable panels based on starch bioadhesives: An insight into structural and tribological performance.

This work was focused on evaluating the effects of polycarboxylic acid addition and retrogradation phenomenon on tribological performance, thermal, and mechanical properties of both, bioadhesives and sustainable panels. The rheological behavior of adhesives was affected by retrogradation, exhibiting formulations containing CA higher elastic modulus than those with BTCA, regardless of the acid concentration. With regard to tribomechanical properties, panels formulated with CA20 and BTCA80 adhesives presented the lower friction coefficient and wear degree. Thermocompression process induced a crosslinking reaction between wood fibers and starch-based adhesives, leading to more hydrophobic and thermally stable matrices in the presence of BTCA. The selection of the adhesive formulation depends on the moment of its use, since retrogradation limits its performance and that of the derived sustainable panels, being the adhesive CA20 more appropriate in freshly prepared formulations. Meanwhile, when the storage of the adhesive prepared in batch is required, the BTCA80 formulation would be more suitable. Thus, bioinspired materials can provide a valuable insight towards incorporating starch-based adhesives for wood applications.

Microstructural and techno-functional properties of cassava starch modified by ultrasound.

This work was focused on the correlation between the structural and techno-functional properties of ultrasound treated cassava starch for the preparation of tailor-made starch-based ingredients and derivatives. Furthermore, the effect of treatment time, sample conditioning and ultrasound amplitude was studied. Ultrasonic treatment of cassava starch induced structural disorganization and microstructural changes evidenced mainly in the morphological characteristics of the granules and in their degrees of crystallinity. These structural modifications were supported by ATR-FTIR and SEM and CSLM studies as well as DRX and thermal analysis. The selection of the processing conditions is critical due to the complete gelatinization of the starch was produced with the maximum amplitude tested and without temperature control. Rheological dynamical analysis indicated changes at the molecular level in starch granules due to the ultrasound treated, revealing the paste stability under refrigeration condition. PCA allow to establish the interrelationships between microstructural and techno-functional properties. In summary, different starch derivatives could be obtained by adjusting the ultrasound treatment conditions depending on their potential applications.