The manufacture of leather covers a wide productive chain and beyond contributes to the economic flow. The various stages of leather processing result in high volumes of solid waste. In Brazil, a daily generation of 375 tons of solid waste is estimated, and landfills are still the most used route to its destination. In this review, emphasis will be given to researches that have sought alternatives for the use of solid waste from the tannery industry. Among the main applications of solid tannery wastes, the following stand out production of adsorbent materials, biodiesel, biogas, biopolymers, applications in agriculture and other applications involving extraction/recovery of compounds of industrial/commercial interest, isolation of microorganisms and production of enzymes and applications in the animal diet. In each alternative of waste application, the technologies used, the opportunities, and the challenges faced are mentioned. We hope that this review can provide valuable information to promote the broad understanding of the possibilities that tannery solid wastes has for the development of biodegradable and agricultural products, wastewater treatment, extraction of compounds of industrial and commercial interest, among others.

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Purpose Acrylamide is a compound found in several food products. Due to the toxicity of this compound, research also seeks strategies to modify industrial and homemade processes, impacting on the reduction of the compound. This paper aims to discuss the aspects surrounding the presence of acrylamide in foods. Design/methodology/approach Published literature on the presence of acrylamide in foods and on its effects has been reviewed. This paper explores the importance of this compound, summarizes the knowledge of its formation and gathers data on its incidence in food and the possibilities of mitigation. Special attention is given to an evaluation of the toxicological tests applied, to analyze whether acrylamide can be considered as a food safety problem. Findings Human exposure to food with high levels of acrylamide varies in their levels regarding the consumption of food in the diet and not only by the level of the compound present in them. Although the compound is well defined as toxic to humans, the association between its intake and most common cancers may not be directly related. Originality/value Depending on the approach of the researchers, contradictory results are obtained, showing the importance of this topic to the development of healthy food products. Further research is still needed to validate the potential effects of acrylamide on human health.

This study aimed to enhance the properties of films produced from corn starch and gelatin recovered from chrome (III) tanned leather waste (CTLW) through the addition of transglutaminase enzyme (TGase) and phenolic extracts from Spirulina platensis (PESP). Mechanical, chemical, physical, and biological properties were analyzed and compared with control films elaborated in the same conditions but with commercial gelatin (COM). The possibility of applying the film as soil cover was analyzed through its degradation when exposed to the surface of a garden soil for a period of 60 days. The TGase caused a reduction of 50% in solubility in water, and 2% in the water vapor permeability (PWV), and PESP caused a reduction of 17% in solubility and 15% in PWV. The combined effect of TGase and PESP was a 60% reduction in solubility, 75% reduction in PWV, inhibition of contamination by Aspergillus niger, and reduction of film degradation on soil covering, evidenced by stability analysis using Fourier transform infrared (FTIR) spectrometry. The combined effect of TGase with PESP led to an improvement in the characteristics of the film produced with CTLW gelatin, rendering its application possible due to a higher lifespan, contributing to environmental sustainability and diminishing leather waste disposal at landfills. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

The production of biodegradable polymers has proved to be a promising alternative, since these materials have accelerated degradation, contributing to the reduction of residues and the reduction of environmental pollution. The tannery wastes contain considerable collagen and can be used for gelatin extraction and film production for use in agriculture. Gelatin-based films, however, present some challenges for practical application, such as permeability and solubility in water, parameters that can be improved through the crosslinking process by employing enzymes, promoting the union of polymeric gelatin chains. In this context, the action of the enzyme transglutaminase was investigated to improve the properties of gelatin films recovered from leather and chitosan residues, which were evaluated according to thickness, solubility, permeability, mechanical properties, and soil degradation. The results indicated that the enzyme concentration in the films had a significant effect on the properties of water permeability and solubility and strain to rupture. The evaluation of soil degradation showed that films with higher enzyme addition took longer to be degraded.