Characterization of the full-scale of browning degrees in liquid food models

DOS SANTOS FERREIRA, CRISTINA; PEPA, LORENA S.; BUERA, MARÍA DEL PILAR; RODRÍGUEZ, SILVIO DAVID

Smolensk

Conferencia; International Conference of the Color Society of Russia; 2020

Color Society of Russia

As a consequence of the universal role that color has in human perceptions, a significant portion of consumer buying decisions is influenced by food color. It is not a specific color that attracts consumers, but that certain colors are considered appropriate for particular products. In the case of foods, when submitted to thermal treatments (cooking, frying, roasting, baking) and even under storage some chemical reactions occur, known collectively as non-enzymatic browning. In the later stages of those reactions, the formation of pigments called melanoidins, provide typical brown coloration. Either if it is desirable feature (such as in bakery products or meat roasting) or a sign of quality loss (indicating decrease of nutritional value or off-flavors production), it is important to fully characterize the color of what is perceived as "brown". Surprisingly, even though brown color is psychologically associated to everyday events, such as meals preparation, gastronomic satiety and gratification, and also serves as a factor for food identification and acceptance, it remains poorly defined. It has been recognized that brown is a special dark color which does not have a single lighter counterpart, and was defined as ?an orange of low brightness and saturation?, or as ?dark color, of various shades between black and red or yellow, a dark color inclining to red or yellow, resulting from the mixture of red and black, or of red, black, and yellow?. Due to the meaningfulness of brown colour in food systems, many approaches are employed to follow its development. Frequently absorbance at a single wavelength, 2D diagrams, a browning index (BI) depending on one chromatic coordinate or just L*, are employed to describe color in the browning processes in many types of food systems. The defined BI was employed in many research papers quite successfully. However, it is to be taken into account that it is defined up to the point in which the samples have light/medium brown colors. Furthermore, the representation of browning development in a CIE 1931 (x, y) plane of the chromaticity diagram leads to the misconception of an approach to the white achromatic point in the later stages, corresponding to dark-brown colorations. In this work, the full range of the browning development was analyzed, through liquid model food systems submitted to thermal treatment, and in commercial liquid samples, including especially the low luminosity range. Three stages could be distinguished in the reaction, ranging from yellow, reddish-brown to dark brown. The results indicated that the evaluation of brown color by using either lightness (1D) or the chromatic aspects (2D) are adequate enough to define the evolution of the processes, but they fail to properly characterize the brown color quality. Also, the commonly employed indexes are not suitable to describe the later stages of browning, corresponding to the darker colors, which are important for many kind of products (such as dark beers, fernet, dark balsamic vinegars, soy sauces, cola beverages). We present a full characterization of browning in 3D spaces. The limits for the appropriate use of the different indexes were also defined, according to the browning stage, and the effects of dilution by water.