Heat-induced changes in dairy products containing sucrose

Characterization of Melanoidins and Color Development in Dulce de Leche, a Confectionary Dairy Product With High Sucrose Content: Evaluation of pH Effect, an Essential Manufacturing Process Parameter

The effect on color of the initial pH employed in dulce de leche (DL) production was evaluated through physicochemical and spectroscopical characterization of the melanoidins formed in the process. Melanoidins originated at pH values of 6.5, 7.0, and 7.5, and they were released by the enzymatic hydrolysis of the protein backbone and purified by gel filtration. They showed a significant degree of polydispersity, in general, with molecular weights (MWs) below 1,800 Da. DL produced at a higher pH released melanoidins with higher average MW after the enzymatic hydrolysis. They also presented darker colors (dE^*ab, C^*), more closely resembling those typical of the commercial product. Analysis of the fractions isolated by gel filtration using HPLC-DAD and multinuclear NMR showed an heterogeneous and complex composition. Even though structurally related, the 1H NMR spectra of melanoidins showed a higher degree of aromaticity at higher pH values. In conclusion, the pH employed in DL production affects the amount and structure of the colored products originated by MR reactions, and thus the color of the final product.

Facile synthesis of highly porous "carbon sponge" with adsorption and co-adsorption behavior of lead ions and atrazine

The rapid industrialization and modern agriculture, increasing emission of heavy metals, and abusing application of pesticide have changed biochemical features of the soil system and water system. Additionally, heavy metals and pesticide compounds may occur together in environments, giving rise to more serious damage to the environment because of their combined toxicity and carcinogenic properties. Therefore, there is a growing need for the development of low-cost adsorbents for their removal. Porous carbon materials have been considered as highly effective materials for pollutant ion control. In this thesis, a novel porous "carbon sponge" is produced using sucrose (S-PCS) with gas-producing molten salt KHCO₃ as the activator at different pyrolysis temperatures under a limited-oxygen condition. Results from these characterizations have indicated that the as-prepared carbon sponges share high surface area (up to 457.6434 m² g^-1) and abundant oxygen-containing functional groups existed on the surface. The essential factors of contact time, initial concentrations, and cyclic availability on adsorption of lead ions and atrazine onto the as-prepared porous samples are also discussed. The typical kinetic and thermodynamic models are carried out to interpret the adsorption behaviors of lead ions and atrazine. The interactive effects and mechanism of lead ions and atrazine adsorption onto S-PCS samples are examined by simultaneous adsorption and preloading adsorption procedures. Combined with the economic and environmental merits of the raw materials, the porous carbon sponges of sucrose by KHCO₃ activated are promising materials for potential practical applications. Graphical abstract The schematic diagram on the preparation of porous carbon sponse from sucrose.

The role of the Maillard reaction in the formation of flavour compounds in dairy products--not only a deleterious reaction but also a rich source of flavour compounds

Dairy products are heated both during processing and by consumers during food preparation; consumers place a high level of importance on flavour when assessing product acceptability. Of particular importance to the flavour of heated dairy products is the highly complex network of Maillard reactions. Much focus has been placed on the undesirable flavours generated through the Maillard reaction and how to minimise the formation of these flavours. However, beneficial flavours can also be formed by the Maillard reaction; dairy products, such as ghee, are formed by heating and are characterised by the unique flavour generated by this chemistry. This review looks at the Maillard reaction as a source of beneficial flavours for cooked dairy products and the application of models to the study of flavour formation in food systems. Models are typically used to study complex reactions in a simplified way; however, they are not always applicable to food systems.