Presentation on theme: "BROWNING IN THERMALLY PROCESSED FOODS: THE MAILLARD REACTION"— Presentation transcript:
1BROWNING IN THERMALLY PROCESSED FOODS: THE MAILLARD REACTION
2Food modifications during thermal treatment (1) Protein denaturationPhysical changes (starch gelatinization, structural alterations of cell wall, depolymerization of dietary fibre)Lipid oxidationDegradation of some bioactive components
3Food modifications during thermal treatment (2) Reaction between different components generate new compounds.Proteins-sugar: Maillard reaction formation of Advanced Glycosilation End-products (AGEs)Lipid-protein: Advanced lipoxidation end products (ALEs)
4The same chemistry The same products The reaction is in both cases (sugars or oxidised lipids) between a carbonyl moiety and an amino groupThe same productsThe final product of both reaction patways (AGEs and ALEs) are polymeric brown macromolecules
5The Maillard Reaction in Foods Produces aromas in heated foodsResponsible for colour formation (non-enzymatic browning)Maillard products have antioxidant propertiesCan cause loss of nutrientsSome products may be toxic
6Stadi avanzati Temperatura e tempo di trattamento termico LATTE UHTLATTE STERILIZZATOBIRRA CHIARAPASTAPRODOTTI DA FORNOBIRRA SCURACACAOCARNE ARROSTITACAFFE’Stadi inizialiStadi intermediStadi avanzatiDiminuzione dell’attività dell’acquaTemperatura e tempo di trattamento termico
7Louis-Camille Maillard (1878 - 1936) Photographed in his laboratory ca 19151912 – 1916: He published 8 papers on his observations of colour changes on mixing amino acids and sugars.No one else took much interest in the reaction until 1950s
8Maillard-Hodge Reaction? John Hodge:Chemist at USDA in Illinois (1941 – 1980)His proposed mechanism for the chemistry of non-enzymic browning is largely unchanged after 60 years.Citations since 1970PaperCitationsHodge, J. E. Chemistry of browning reactions in model systems. J. Agric. Food Chem. 1953, 1:890Maillard, L. C. Action des acides amines sur les sucres: formation des melanoidines par voie methodique. Compt. Rend. 1912, 154:634Maillard-Hodge Reaction?
9Hodge SchemeHodge J E. Dehydrated foods: chemistry of browning reactions in model systems. J. Agric. Food Chem. 1:928-43, 1953.
10First step: formation of Amadori product PRODOTTO DI AMADORI
16Food “melanoproteins” Food “melanoproteins”NRCHO3LysineNOR'HProtein AN+H2ORRNO'Protein B
17Pronyl-lysineThis compound is formed on the lateral chain of Lysine residuesPronyl-lysine has a high antioxidant activity
18Development of mitigation strategies to reduce their concentration Possible toxicantsAcrylamideFuranHeterocyclic amines3-MPCD (Mono Chloro Propan Diol)3-Methyl ImidazoloneDevelopment of mitigation strategies to reduce their concentration
19A network of many reactions giving thousands of products Products formed depends on:Chemical nature of the reactantsTime and temperature of heatingTechnological conditionsWater activity, pH
20Practice Effects of reactants: Sodium Carbonate (pH effects) Protein and carbohydratesWater activity (fibre addition)Butter clarificationControlAdded with sodium bicarbonate