Vol.:(0123456789) 1 3 Biomass Conversion and Biorefinery https://doi.org/10.1007/s13399-023-04547-5 REVIEW ARTICLE Valorization of animal by‑products for gelatin extraction using conventional and green technologies: a comprehensive review Muhammad Usman 1  · Anum Ishaq 2  · Joe Mac Regenstein 3  · Amna Sahar 1,4  · Rana Muhammad Aadil 1  · Aysha Sameen 5  · Muhammad Issa Khan 1  · Amna Alam 1 Received: 25 April 2023 / Revised: 20 June 2023 / Accepted: 25 June 2023 © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023 Abstract A large number of animal by-products including the bones, skins, tendons, scales, and feet are being generated around the world. These by-products are produced by meat processing facilities, slaughterhouses, and fsh processing units. These are often put into landflls without any treatment, thus causing environmental pollution. However, these by-products can be used for the production of valuable compounds such as collagen and gelatin that can be used in diferent food products. Gelatin is the most widely used hydrocolloid in the world. By the year 2025, the market size of gelatin will exceed ~ $5 billion and is predicted to reach $6.7 billion in 2027. Therefore, gelatin recovery is benefcial both economically and environmentally. Commercially available gelatin is derived from porcine and bovine bones and skins. There are several other by-products from which gelatin can be extracted including by-products from chickens, ducks, fsh, and camels. The increase in sustainable and green technologies that eliminate the usage of toxic solvents and less time for extraction has increased the demand for novel extraction processes in the food industries. The application of more recently developed techniques can be used for the extraction of gelatin to overcome several limitations of the traditional process. The present review discusses the application of conventional (hot water bath) and advanced technologies (ultrasound, microwave, or enzyme-assisted extraction) to extract the gelatin from diferent animal by-products. The physicochemical properties of gelatin depend on the source, extraction conditions, and pretreatment methods. These advanced techniques improve the functional properties, quality, and process efciency of gelatin. Keywords Food waste · Gelatin · Waste utilization · Extraction · Ultrasound · Microwave 1 Introduction Food waste is a global issue which accounts for the wastage of around 1.3 billion tons/year of food produced for con- sumption. In developing countries, this waste account for $310 billion, while developed countries account for almost $680 billion [1]. The food industry generates a large amount of biodegradable by-products in diferent forms, both solid and liquid. These waste by-products are composed of organic resides. Globally, 1.3–1.4 billion tons volume of food waste was observed and by 2025, it is expected to increase up to 2.6 billion tons. According to United Nations Environment Programme (UNEP) reports, about $400 billion in economic loss was generated by food waste [2]. During the production and processing of meat/fsh/poultry, fruit, and vegetables, 35.9 MMT of food loss is estimated in the USA alone [3]. Of the total by-products produced, 8% is generated by the meat industry, 26% by the beverage industry, 14.8% by the pro- cessing/production of fruit and vegetable, 0.4% by the fsh industry, 21% by the dairy sector, and 3.9% by oil sector [4]. Meat processing industries generate waste exceeding 100 million tons per year [5]. On average, waste generated by * Amna Sahar amnasahar@uaf.edu.pk 1 National Institute of Food Science and Technology, University of Agriculture, Faisalabad 38000, Pakistan 2 School of Food and Agricultural Sciences, University of Management and Technology, Lahore, Pakistan 3 Department of Food Science, Cornell University, Ithaca, NY 14853-7201, USA 4 Department of Food Engineering, University of Agriculture, Faisalabad 38000, Pakistan 5 Department of Food Science and Technology, Government College Women University, Faisalabad, Pakistan