Avaliação da estabilidade de produtos lácteos através de análise físico-química, espectroscópica e imagens digitais

Abstract

The oxidative action of some microorganisms and chemicals present in dairy products can change their acidity and pH levels, contributing to the darkening of the product. Consequently, color appearance is one of the first factors to be considered by the consumer, influencing product acceptance or rejection. In the food industry, the color parameter is measured by colorimeters and spectrophotometers; however, the use of digital images for quantitative colorimetric tests has been researched and can be applied in several areas, including food. The processing of digital images is based on the RGB (red, green, blue), HSV (hue, saturation, value) and Gray Scale color systems, in which the measurement is by algorithms developed in a computational environment. Therefore, the present work aims to investigate for 45 days the chemical, physicochemical and colorimetric changes of the creamy dairy dessert white chocolate flavor and strawberry flavored yogurt. These changes were monitored by analyzing the parameters pH, acidity, soluble solids content, humidity, rheological characterization, as well as mid-infrared spectroscopy and digital images. All measurements were performed in triplicate over a period of 0 to 45 days at intervals every 15 days and subsequently processed in a computer environment. Stability tests were also performed exposing the samples to ultraviolet radiation (UV) and temperatures at different times in order to visualize the deterioration conditions of the products. In this way the quality and stability can be verified over the shelf life established by the manufacturer. Based on the data obtained, it was found that there were changes in the parameters evaluated, and the acidity of milk dessert remained constant during the storage time. From the Principal Component Analysis using the color variables, it was observed that the samples were grouped and separated by type and storage time according to the visually observed colorimetric modifications. Stability tests indicated that storage time and exposure time to ultraviolet radiation (UV) were the variables that most influenced acidity, pH and soluble solids results.