Learning outcomes of the course unit
Knowledge and understanding
During the course the studente will acquire a deep knowledge of the chemical composition of foods, of the characteristics of the different components, of their influence on the food properties, of their reactivity and of the transformations they undergo during the technological processes as well as of the analytical issues linked to their determinations.
The student should acquire the ability to correlate and integrate general aspects with specific characteristics of the different food products, understanding the correlation existing between chemical composition and quality and acquiring the ability to elaborate label informations.
These knowledges are the base to effectively operate in the production, control and analytical sector as well as to design new products and processes.
Applying knowledge and understanding
The student must be able to utilize the acquired knowledges to understand and foreseen the molecular transformations in foods as a consequence of technological processes and storage.
The student must be able to define which transformations may occur or may be induced in a food and which are the effects of the different formulations on the general properties and the quality of a food product as well as to identify the processing or storage conditions that may influence the overall quality of a product.
The student should be able to appropriately utilize the scientific language and the specific lexicon of food chemistry, showing the ability to describe and transfer in oral and written form the acquired concepts.
The student will be able to increase his/her knowledge of Food Chemistry, by self consultation of specialized texts, scientific and divulgative journals, also beyond the topics discussed during the lessons.
Students should have already passed the examinations of General Chemistry, Organic Chemistry and Analytical Chemistry.
Course contents summary
The Food Chemistry course is composed of a first general part focussed on the description of food macrocomponents (water, carbohydrates, proteins, lipids) and of their chemical, physical and technological properties, the study of their general reactivity as well as of the analytical methods to assess the proximate composition of food products.
The second part takes into account several food products of animal and vegetal origin, describing their composition, the main production and storage technologies and the chemical and physical transformations occurring during processing and storage, as well as the analytical aspects linked to their characterization.
The last part of the course is focussed on more general topics, in particular: hints to food additives and their use as well as the description of the most important classes of undesirables substances linked to food safety issues.
Introduction. What is Food Chemistry?
Water. Water structure. Interactions of water with food components and matrices. Bound water, water activity (aw): definition and correlation with % equilibrium relative humidity. Sorption isotherms: meaning and use. Methods for the determination of % humidity of foods (dehydration, distillation, Karl-Fischer titration, IR, NIR, thermobalance), of ash (in oven or with acids) and water activity (hygrometers, lithium chloride sensors, dew point sensors). Mineral waters (potability characteristics and compositions).
Carbohydrates. Monosaccharides and oligosaccharides in foods: structure, properties and occurrence. Cane and beet sugar. Inverted sugar, glucose syrups: preparation and applications. Alditols: preparation and application. Decomposition of sugars in foods with acids, alkali and heat treatment. Hydroxymethylfurfural, maltol and isomaltol, lactulose. Caramellization and caramels. Maillard reaction. Methods for analysis of carbohydrates. Polysaccharides. Starch. Gelification and retrogradation. Modified starch and starch syrups. Amylases. Pectins. Pectinesterases and pectinlyases. Algal polysaccharides (alginates and carragenans). Cellulose, hemycellulose and fibers. Methods of analysis of food fiber. Gums (arabic gum, xanthan gum). Physico-chemical properties of polysaccharides and their applications in food products. Fermented products: alcoholic beverages, wine, aceto and beer. Lipids. Fatty acids: structure and their occurrence in foods. Melting points and physical properties of oils and fats. Reactions of unsaturated fatty acids. Hydrogenations, margarin and trans fatty acids. Degradation oxidative reaction and rancidity (autooxydation, fotooxydation and enzymatic oxydation, lipooxygenases). Natural and synthetic antioxydants: classification, properties and mechanism of action. Control parameters for oxydation phenomena in oils. Triglycerides. Crystalline forms of triglycerides: fat melting and crystallization. Chemical composition and properties: cocoa butter and chocolate. Interesterification. Vegetal oil, milk fat, cream and butter: classification, composition, production and refinement. Emulsions. Natural and synthetic emulsifiers: characteristics and applications. HLB parameter. Sterols. Polar lipids. Cholesterol and phytosterols: chemical characteristics, occurrence and stability. Analytical methods of fats.
Proteins. Amino acids and proteins in foods. Degradation reactions of amino acids and proteins in foods: heat and pH effects. Denaturation, racemization, isopeptides, lysinoalanine, furosine. Analytical methods. Technological properties of proteins (humectants, emulsifying, foaming, gelling, etc.). Proteinaceous foods. Milk: classification, structural components of milk, caseins and serum proteins, casein micelle structure, lipids and fat globules, lactose, thermal treatments and homogenization of milk and effects on milk components, analytical methods of milk. Cheese: classification and composition, coagulation and chemical modification during ageing, proteolysis, proteolysis index, nitrose fractions, principal analyses. Meat and fish: classification and composition, characteristics of meat proteins, post-mortem changes, anomalies (DFD, PSE), myoglobin and meat colour, additives, cured meat products (sausages), principal analyses. Eggs: composition, characteristics of egg proteins, technological properties, egg products. Cereals and derivatives: chemical composition of cereals, cereal proteins, classification and properties, gluten: formation and properties, flour and semola, rheological properties of flours, bread and pasta, bread additives, effect of heat treatment and drying.
Food color. Molecular bases of color. Color measurement: colorimeters and spectrophotometers. Natural colors: chlorophyll, carotenoids, antocyanins, betalains, melanins, curcuma and cochineal red. Synthetic dyes.
Flavour: aromas and tastes of foods. Taste: sweet, bitter, salty, ac
T. P. Coultate, “La Chimica degli Alimenti”, Ed. Zanichelli (Bologna, 2004); P. Cabras, A. Martelli, "Chimica degli alimenti“, Ed. Piccin (Padova, 2004); H.D. Belitz - W. Grosch – P- Schieberle, “Food Chemistry”, Springer-Verlag Ed. (Berlin, Germany, 2005); O. R. Fennema, “Food Chemistry”, CRC Press Ed. (New York, USA); P. Cappelli, V. Vannucchi "Chimica degli alimenti-Conservazione e trasformazioni" Ed. Zanichelli (Bologna, 2004).
Power point presentations of the different topics.
During the lessons, which will be done using power point projections, overheads and blackboard, the different aspects of foods and of their production will be presented and , with a particular emphasis on the chemical and physical transformations and their control.
Assessment methods and criteria
Final examination will be written and oral. The written examination will contain open questions on the main course topics, both on the aspects of the most important chemical reactions and on the descriptive aspects of food composition and properties and of food components.
Oral examination will be focussed on the discussion of the written text, integrated by another topic discussed during the course.
Attendance to the lessons is not mandatory, although strongly encouraged.