Extração e caracterização de gelatina a partir do resíduo de CMS de rã-touro (Lithobates catesbeianus)

Abstract

The search for healthy foods has provided an increase in the consumption of american bullfrog (Lithobates catesbeianus) in Brazil. However, its processing generates a large amount of waste made up of bones and cartilage. These residues constitute high quality raw material for obtaining gelatine with wide application in the pharmaceutical, food, cosmetic and photographic industries. Gelatin is a natural polymer formed by a mixture of biopolymeric peptides and proteins, obtained by the partial hydrolysis of collagen. In this context, the present work aimed to extract gelatine from the use of a mechanically separated meat residue (RCMS) from bullfrogs and its proper characterization. For the extraction of gelatins were used two different methods: 1. Use of a pre-treatment, based on demineralization, treatment with NaOH and acidification with hydrochloric acid, followed by extraction of gelatin in distilled water under heating at 60 ºC for two hours, called gelatin with pre-treatment (GCPT); and 2. use of only the extraction of gelatine in distilled water under heating at 60 ºC for two hours, called gelatin without pretreatment (GSPT). The extracted gelatins were characterized for total protein, ash, hydroxyproline, gel strength, pH, color, amino acid composition, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The pre-treatment method was the one that presented the best gelatin extraction condition in relation to physicochemical and technological properties, being then chosen to be characterized in relation to the quality parameters required by national and international legislation, applied to commercial gelatins. The results indicated that GCPT from bullfrog RCMS was isolated with greater success, that is, with higher levels of purity, due to lower ash content, higher protein and hydroxyproline contents. The extraction method influenced the physical, chemical, structural and technological properties of the bullfrog RCMS gelatins, these properties being better for the gelatin obtained with pre-treatment (GCPT), with potential for industrial application, highlighting mainly the significant value of gel strength, low gray content, close to white color and good thermal properties for applications below 200°C. GCPT meets the physical-chemical quality parameters established by current legislation. However, in terms of microbiological quality, a greater hygienicsanitary control in the production and storage process is suggested in order to avoid contamination and ensure greater quality to the extracted product.