Learning objectives
To describe and illustrate the chemical composition of foods, the characteristics of the different components, how they influence food properties, their reactivity and transformation during technological processes as well as the analytical methods for their determination. <br />
Prerequisites
The final examination should be preceded by Organic Chemistry and Analytical Chemistry.
Course unit content
Introduction. What is Food Chemistry? <br />
Water. Water structure. Water interactions with food components and matrices. Bound water, water activity (aw): definitions and correlation with % equilibrium relative humidity. Adsorption isotherms: meaning and usefulness. Methods of measurement of water content in food (dehydration, distillation, Karl-Fischer titration, IR, NIR, thermobalances), of ash and of water activity (hygrometers, lithium chloride sensors, dew point sensors. Mineral waters: a brief overview on composition and analyses. Carbohydrates. Monosaccharides and oligosaccharides in foods: structures, properties and occurence. Cane sugar and beet sugar. Inverted sugar, glucose syrups: preparation and applications. Alditols: preparation and applications. Sugar decomposition in food by acid, alkali or thermal treatment. Hydroxymethylfurfural, maltol, isomaltol, lactulose. Caramelization and caramels. Maillard reaction. Analytical methods for carbohydrates. Polysaccharides. Starch. Gelification and retrogradation. Modified starches and starch syrups. Amylases. Pectins. Pectinestherasese and pectinlyases. Polysaccharides from marine algae (alginates and carragenans). Cellulose, hemycellulose and fiber. Analyses of fiber. Gums (arabic, xanthan). Chemical-physical properties of polysaccharides and applications in food. Chemistry of fermented products: alcholic beverages, wine, vinegar and beer. Lipids. Fatty acids: structure and occurrence in food. Melting point and physical properties of oils and fats. Recativity of unsaturated fatty acids. Hydrogenation, margarine and trans fatty acids. Oxidative degradation and rancidity (autooxidation, photooxidation and enzymatic oxidation, lipooxygenases). Natural and synthetic antioxidants: classification, properties and mechanism of action. Control parameters for oxidative phenomena in oils. Triglycerides. Crystalline forms of triglycerides: melting and cristallization of fats. Chemical composition and properties: cocoa butter and chocolate. Interesterification. Vegetable oils, milk fat, cream and butter: classification, composition, production and refining. Emulsions. Natural and synthetic emulsifiers: characteristics and applications. The HLB parameter. Sterols. Polar lipids. Cholesterol and phytosterols: chemical characteristics, occurrence and stability. Analysis of lipids. Proteins. Amino acids and proteins in food. Degradative ractions of amino acids and proteins in food: temperature and pH effects. Denaturation, racemization, isopeptides, lysinoalanine, furosine. Analitycal methods. Technological properties (hydration, emulsifying ability, foaming ability, gelling, ecc.). Milk: classification, structural components, caseins and serum proteins, casein micelle structure, lipids and fat globules, lactose, thermal treatment and homogeneizationof milk and effect upon components, analyses of milk. Cheese: classification and composition, coagulation and chemical modification during ageing, proteolysis, proteolysis index, nitrogen fractions, analyses. Meat and fish: classification and composition, characteristics of meat proteins, post-mortem modification, defects (DFD, PSE), myoglobin and meat color, additives, sausages, analyses. Eggs: composition, characteristics of egg proteins, technological properties, egg products. Cereals and cereal products: chemical compositions of cereals, cereal proteins, classification and properties, gluten: formation and properties, flour and semolina, reological properites of flours, bread and pasta, bread additives, cooking and dehydration effects. Color of foods. Molecular basis of food color. Color measurement: colorimeter and spectrophotometer. Natural colorants: chlorophylls, carotenoids, anthocyanins, betalains, melanins, curcumin and cochineal. Synthetic colorants. Food flavor: aroma and taste of foods. Taste: sweet, bitter, salty, sour, astringency, pungency, umami. Aroma: meat, fruits, vegetables, herbs and spices, synthetic flavourings, off-flavours and contaminants. Basics of sensorial analysis. Food additives. Classification and numbering. Chemical properties of the main classes of additives (preservatives, antioxidants, emulsifiers, ecc.). Vitamins. Classification. Properties, analyses and degradation in foods. Undesirables. Basics of toxicology. Classes of undesirable substances in food. Plant toxins. Marine toxins. Mycotoxins. Bacterial toxins. Allergens. Toxic residues from agriculture. Heavy metals. Xenobiotics. Contaminants from packaging and environment. <br />
Bibliography
T. P. Coultate, “La Chimica degli Alimenti”, Ed. Zanichelli (Bologna, 2004). <br />
P. Cabras, A. Martelli, "Chimica degli alimenti“, Ed. Piccin (Padova, 2004) <br />
H.D. Belitz - W. Grosch, Food Chemistry, Springer-Verlag Ed. (Berlin, Germany, 2005) <br />
O. R. Fennema, Food Chemistry, Marcel Dekker Ed. (New York, USA) <br />
P. Cappelli, V. Vannucchi "Chimica degli alimenti-Conservazione e trasformazioni" Ed. Zanichelli (Bologna, 2004) <br />
Pearson's Chemical Analysis of Food – Churchill Livingstone Ed. (London, UK). <br />
Tateo: Analisi dei composti alimentari vol 1,2 Chiriotti Ed. <br />
Teaching methods
The course is based on oral lessons and laboratory exercises. The evaluation is based on written examinations during the course and a final written and oral examination on the theoretical contents and on the laboratory exercises described in a lab book by the student.
