Co-imobilização de β-galactosidase e lipase em filmes de blenda de gelatina-carboximetil celulose utilizados como componente de embalagem ativa para produtos lácteos

Abstract

Dairy consumption faces challenges related to digestion and general absorption, such as lactose intolerance and high levels of saturated fat and sugar, leading the industry to develop processes suitable for the production of foods with specific characteristics. Thus, β-galactosidase (3% w/w) and lipase (2% w/w) were co-immobilized in polymeric blends of Gelatin (GEL) and Carboxymethyl cellulose (CMC) prepared with different GEL:CMC ratios (v/v): A (0:100), B (25:75), C (50:50), D (75:25) and E (100:0). The compatibility of the polymers and the interaction with the added enzymes were evaluated through scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy using the attenuated total reflection technique (FTIR-ATR). Mechanical tests were performed to evaluate the tensile strength and the barrier properties were defined by the water vapor permeability test (WVP). Thermal properties were defined by differential scanning calorimetry (DSC) and thermogravimetry (TG and DTG) tests and the relative crystallinity was obtained by X-ray diffractometry (DRX). Colorimetric enzymatic tests were performed to evaluate the hydrolysis of lactose and triglycerides and the efficiency of the active films was evaluated by FTIR-ATR. As a result, the films presented regular and uniform structure, greater barrier to UV light for films with higher GEL content in their composition, however, they formed less transparent films. The addition of CMC gave the film greater mechanical strength, presenting a tensile strength 82.8% higher than the GEL films, the addition of enzymes had no effect on the mechanical strength, but increased the elongation of the films. TG showed that CMC provides greater thermal stability to the active films and a higher residual mass, in addition to greater interaction of the enzymes with the bulky groups of CMC, confirmed by DSC and a higher crystallinity of up to 5.8% compared to the Gel film. CMC was the most hydrophilic polymer, with a higher moisture content of 57.7% and PVA 100% higher compared to GEL. The active films presented greater enzymatic activity compared to the activity of the enzyme in its free form, favoring the process of immobilization of the enzymes in the GEL:CMC films, increasing process safety and reducing operating costs.