Color determination in dehydrated fruits: image analysis and photocolorimetry

MARCELA AGUDELO; NURIA ACEVEDO; CAROLINA SCHEBOR; PILAR BUERA

Color in Food: Technological and Psychophysical Aspects

CRC Press

Lugar: Boca Raton; Año: 2012; p. 155 - 162

The appearance of food is the first quality aspect evaluated by consumers and is critical in the acceptance of the products. The color of the food surface is the first sensation that the consumer perceives and uses as a tool to accept or reject the product (León et al. 2006). Foods containing reducing sugars and proteins are particularly sensitive to browning reactions. Solubility decrease, color development and the loss of nutritional value are the most important causes of deterioration associated with browning in foods (Buera et al. 1987). Dehydrated fruits are considered to be highly stable; however, they are prone to suffer discoloration during storage. Many natural pigments are unstable in dried media, and also brown pigments can be formed. These color changes cause deleterious changes in food appearance and organoleptic quality, and may be an indication of the decreased nutritional and functional properties of foods. Discoloration can occur homogeneously, but most of the times heterogeneous distribution of color is observed. In the last few years emphasis has been placed on techniques applying computer vision systems and image analysis for assessing the browning degree and other properties related to food quality (Briones and Aguilera 2005). Computer vision systems use devices for image acquisition, hardware and software for processing the images to simulate the role of the eyes and brain. Computer vision offers a spatial resolution as it covers the whole object of interest, which is not possible with tristimulus colorimeters which require measurements point to point of the object and provide, therefore, average values of color from very small areas. Digital cameras capture the colors while the computers store them. The image acquisition by a camera and the processing using appropriate programs represents an interesting alternative for heterogeneous systems, because they provide a large quantity of information in a practical method (Jayas et al. 2000). Recent studies have shown that computer vision systems are reliable to determine different color and appearance aspects (Briones and Aguilera 2005; Mendoza et al. 2006; Venir et al. 2007) and browning development (Acevedo et al. 2008) in food. The objective of this work was to evaluate the kinetics of color changes in different dehydrated fruits as a function of relative humidity at different storage times after heat treatment at 45º C.