Study of the Diffusion Phenomenon of Natural Dyes in Preserved Polyol Cherries

Abstract

The ongoing thesis pertains to the potential substitution of artificial colourants in candied cherries with plant-based dyes derived from radish, beet, and gardenia. This endeavour aligns with the escalating consumer demand for healthier and more natural food products. The research encompasses a comprehensive analysis of the stability and diffusion kinetics of these natural colorants within the cherry matrix during a candying process. The initial phase is dedicated to characterising the stability of the selected natural colourants under diverse processing conditions, including their resilience to temperature variations, light exposure, and pH fluctuations. Subsequently, the investigation delves deeper into the intricate diffusion process of the colorant within the cherry tissues. Employing experimental techniques and mathematical models, the diffusion kinetics of each colourant in both skin and cherry flesh during sweetening with a 50% sucrose/50% xylitol formulation of 35 Bx was quantified. This entailed the analysis of crucial processing variables such as temperature (40, 50, and 60°C), dye concentration (119, 238, and 357 ppm) during impregnation time on the transport rate and extent of pigment diffusion. A predictive mathematical model (1D) was devised to comprehend the mechanisms dictating the transport of dye within the fruit matrix. This marks an initial step, affording the opportunity to progress into higher dimensions (2D and 3D), with the aim of refining the optimisation of the candied process. Part of the methodology and findings outlined have been previously published in Nature's Scientific Reports.