Aplicação da invertase em embalagens ativas para prevenção da cristalização da sacarose em doces em massa de banana-nanica (Dwarf Cavendish)

Abstract

In order to reduce the crystallization of sucrose in banana paste, the invertase enzyme was incorporated into chitosan packaging. Firstly, the enzymatic activity of the free invertase enzyme was verified and greater activity of this enzyme was observed at pH 5 and 55 °C. The films were produced by the casting method with and without pH adjustment (using 10 M NaOH) for comparison purposes, incorporated with invertase (1-10%) and were characterized according to the concentrations: 1.2, 5, 9 and 10% invertase enzyme in chitosan packaging. The chemical structure revealed differences between films with and without pH adjustment, but the invertase did not differ in this regard, but showed a plasticizing effect in relation to SEM images. The thickness increased with pH adjustment and the mechanical properties were influenced by pH and also by the concentration of invertase, which may have acted as a plasticizer, which was also responsible for the increase in solubility and PVA. Optical properties were little affected, with films being transparent in the visible range and blocking UV light. Finally, TGA indicated similar thermal degradation behavior for all films. With the characterization of the packaging, those that were incorporated with 1, 5 and 10% of invertase in addition to the chitosan film without invertase as well as the control treatment (without packaging) and commercial film (cellophane paper) packaged paste in dwarf banana mass and these sweets were evaluated over 120 days, considering physicochemical analyzes as well as crystallization evaluation (XRD and microscopic analysis). The treatments showed loss of pH stability, associated with increased acidity, with pH below 4.5 being beneficial for conservation. Active packaging influenced reducing sugars, with invertase contributing to the maintenance of acidity. The water activity reduced due to the sugar in the formulation. There was instability in soluble solids, influenced by temperature and packaging. The color of the sweets remained generally stable. The increase in hardness over time, observed in most sweets, is possibly related to the increase in soluble solids and the reduction in water activity. Chitosan and cellophane packaging, with high moisture permeability, can promote water loss, contributing to firmness. Cohesiveness decreased over the 120 days in all packaging and in the control without packaging, indicating changes in the structure of the sweets. X-ray diffraction revealed an increase in the crystallinity of sugars, especially in the control and 0% chitosan treatments, indicating a possible influence of the invertase enzyme in reducing the intensity of crystallinity. The crystal size distribution revealed a considerable increase in the size of crystal diameters at 60 days, especially in sweets packaged without invertase enzyme. The invertase enzyme contributed to reducing the size of the crystals, indicating a possible improvement in the quality perceived by consumers, as it reduces the granular sensation of sugar in the products. Therefore, chitosan packaging incorporated with the invertase enzyme has great potential for packaging fruit sweets that suffer from the sucrose crystallization process.