Gelatin from Tannery Wastes

Waste byproducts that interest renewable materials researchers usually come from plant-product processing, but animal processing produces its own potentially useful waste materials. Tannery wastes from hide processing in particular are being targeted by European government regulators: “Member States are required not only to take measures in order to minimise waste production by developing clean technologies, but also to encourage their recovery and valorization,” note researchers from footwear research center INESCOP, in Spain.

Looking to turn tannery wastes into useful co-products, the INESCOP researchers report work on the creating gelatin (alternate spelling: gelatine) from them for microencapsulation applications, “a coating technology by which active substances are coated in a polymeric shell, leading to core-shell particles called microcapsules.” Their work was published in February’s “Special Issue from the 6th Workshop on Green Chemistry and Nanotechnologies” of the Journal of Renewable Materials.

M.A. Pérez-Limiñana et al. Influence of the Extraction Temperature (c)2016 J Renew Mater

“Microcapsules obtained by complex coacervation” from M.A. Pérez-Limiñana et al., ©2016 Journal of Renewable Materials.

Gelatin, “a soluble protein obtained by partial hydrolysis of collagen,” can be extracted from untanned solid waste in several steps, using the right conditions, producing a material with the properties for microencapsulation. Typical steps include an alkaline collagen pre-treatment, which produces a lot of wastewater and can take a lot of time. However, “enzymatic pre-treatment opens up a new alternative to the alkaline pre-treatment to reduce processing time and wastewater,” the authors explain.

They analyzed gelatins produced from bovine pelt wastes at different extraction temperatures and determined their chemical compositions and molecular weights. One key property for analysis was the gel strength (or “Bloom value”), which determines the quality of the gelatin.

Optimized enzymatic pre-treatment and extraction temperatures “allow medium-grade gelatines to be obtained with suitable properties for microencapsulation applications,” they found. “The extraction temperature determines gelatine yield, gelatine properties and, therefore, its microencapsulating ability.” More work is being carried out to produce high-grade gelatins from tannery wastes, they add.


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