Food Chemistry and Laboratory of Chemistry Applied to Food
Learning outcomes of the course unit
Knowledge and understanding
During the course the student 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 information.
These knowledges are the base to effectively operate in the production, control and analytical sector as well as to design new products and processes. Understanding of the analytical parameters to be determined and of the methods to be applied for the analysis of a food matrix, both qualitative and quantitative. Ability to use the specific language of food chemistry.
Applying knowledge and understanding
The student must be able to utilize the acquired knowledge to understand and foreseen the molecular transformations in foods as a consequence of technological processes and storage.
During the course, the student will perform laboratory experiments linked to the theoretical part and aimed at understanding the chemical transformations of principal and secondary food components as well as their determination and characterization, showing the most important analytical methods of food and transferring operative abilities. Ability to manage the principles underlying the methods for the chemical analysis of food matrices in order to decide independently which tests to apply on food and why to apply them.
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 must be able to independently assess which methods to choose and apply to fully characterize a food matrix.
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 lab book should be written correctly, with a synthetic but proper language and with a clear exposition and comment of the experimental data.
The student will be able to increase his/her knowledge of Food Chemistry, by consultation of specialized texts, scientific and educational journals, also beyond the topics discussed during the lessons. Students must be able to summarize and correlate the various topics covered in the other courses of the degree program.
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 and the chemical and physical transformations occurring during processing and storage, as well as the analytical aspects linked to their characterization.
The third part of the course is focused on more general topics, in particular: hints to food additives and their use as well as the description of organoleptic characteristics of food (color and flavor).
The topics discussed during lessons are also the subject of lab experiments aimed at illustrating characteristics of food and the most used analytical techniques.
In particular, for the chemistry laboratory, the first lessons are about general topics relating to the techniques and basic instruments used in a food chemistry laboratory. The second part of the course is dedicated to the discussion and application of specific methods for the qualitative and quantitative analysis of foods. In fact, in the first part of the course, methods and protocols involve a limited number of steps, whereas in the second part more complex experiments are considered, to finally consider instrumental techniques. The last lab exercises are dedicated to the treatment of the data obtained during the experiments.
Module: Food Chemistry
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, thermobalances), of ash (in oven o with acids) and water activity (hygrometers, lithium chloride sensors, dew point sensors). 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. Lab experiments: determination of reducing sugars and saccharose in fruit juice with Lane and Eynon method. Determination of amylose and amylopectin in food products. Maillard reaction. Gel formation with alginates. Sugar content of must. Acidity and alcoholic grade of wine. Saccharimeters, densitometers and refractometers. Lipids. Fatty acids: structure and their occurrence in foods. Melting points and physical properties of oils and fats. Reactions of unsaturated fatty acids. Hydrogenations, margarine and trans fatty acids. Degradation oxidative reaction and rancidity (autooxidation, fotooxidation and enzymatic oxidation, lipooxigenases). Natural and synthetic antioxidants: classification, properties and mechanism of action. Control parameters for oxidation 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. Lab experiments: determination of fat content of foods by Soxhlet. Determination of peroxide number and acidity in oils. Determination of spectrophotometric parameters in olive and seed oil (K and K). Emulsions and emulsifiers. Determination of cholesterol in pasta samples. Determination of fatty acid composition of fats and oils by gas chromatographic analyses. 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. 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. Lab experiments: determination of protein content of food by Kjehldal. Qualitative tests for proteins. Protein coagulation. Emulsifying properties of proteins. Foam formation. Gelatin. Texturalization of vegetal proteins (soy). Myoglobin: color changes upon heat treatment and use of nitrites. Food color. Molecular bases of color. Color measurement: colorimeters and spectrophotometers. Natural colors: chlorophyll, carotenoids, antocyanins, betalains, melanins, curcuma and cochineal red. Synthetic dyes. Lab experiments: pH and temperature effect on food color: chlorophyill, antocyanins. Flavour: aromas and tastes of foods. Taste: sweet, bitter, salty, acid, astringency, hot, umami. Aroma: meat, fruits, vegetables, aromatic herbs and spices, synthetic flavouring agents, off-flavor and contaminants. Sensorial analyses. Additives. Classification and numbering. Chemical properties of food additives (preservatives, antioxidants, emulsifyers, ecc.).
Module: Laboratory of Chemistry Applied to Food
Techniques for preparing and analyzing solutions, extraction and chromatographic separation techniques, techniques for the synthesis of molecules of food interest, techniques for the purification of extracts, techniques for food analysis and finally also techniques for treatment of the data obtained from analysis will be considered. The course therefore includes: the study of the preparation and analysis of standard solutions; quantitative analysis by titration; extraction of bioactive compounds from food matrices and evaluation of the purity of the extract through instrumental measurements; study of the recovery and behavior of natural dyes; synthesis, purification and analysis of aromas of food interest; methods for the determination of sugars in a food matrix; methods for the determination of amino acids and proteins in food; evaluation of thermal processes in a food (study of the Maillard reaction); analysis of the fat component of a food; emulsifying properties; use of instrumental techniques such as UV-Visible spectrophotometry to determine the presence and quantity of particular compounds in foods and / or beverages; gas chromatography coupled to mass spectrometry (GC-MS) and liquid chromatography (HPLC); basic instrumentation for a food chemistry laboratory such as Soxhlet extractor and Kjeldhal method; processing of data deriving from analysis using specific software.
Text books: Luisa Mannina, Maria Daglia, Alberto Ritieni (a cura di) “La chimica e gli alimenti. Nutrienti e aspetti nutraceutici” Casa Editrice Ambrosiana (Milano, 2019); T. P. Coultate, “La Chimica degli Alimenti”, Ed. Zanichelli (Bologna, 2004); P. Cabras, A. Martelli (a cura di) "Chimica degli alimenti“, Ed. Piccin (Padova, 2004); Paolo Cabras, Carlo I. Tuberoso, “Analisi dei prodotti alimentari”, Piccin (Padova).
Other useful study books: 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); Leo M. L. Nollet eds., Handbook of Food Analysis, Marcel Dekker (New York, USA).
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.
The course will be integrated by lab experiments, with individual and practical experiments aimed at understanding theoretical and practical aspects of food behaviour, as well as at illustrating the most important analytical methods also the instrumental ones.
Lab experiments will be described by each student in a lab book, that will be a completing part of the final evaluation.
Assessment methods and criteria
As far as the module of Food Chemistry, final examination will be written. The written examination will contain 6 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 (score: max 5 points for each question).
If it is impossible to carry out the written exam in person due to force majeure imposed by the University on account of COVID-19 epidemic, an oral exam will be carried out remotely through Teams.
The evaluation of the Food Chemistry module will contribute 50% to the final evaluation of the overall exam.
In order to evaluate the understanding of the topics illustrated during the course, both in the classroom practice phases and in the laboratory exercises, and the student's ability to independently re-elaborate the concepts, the laboratory exam is divided into 2 parts:
1. Oral exam: consisting of open-ended questions relating to the topics covered in the course, for a maximum of 24 total points. The questions verify the achievement of the minimum knowledge of the fundamental concepts of the course and may include one or two calculation exercises. The exam is considered passed if the minimum threshold of 14.5 points is reached.
2. Compilation of the laboratory notebook: the laboratory notebook requires the student to draw up a report for each of the practical experiences carried out in the laboratory. In each report, the procedures of the experiment must be indicated and well described, the fundamental steps that made it possible to achieve the results obtained, including safety and preventive measures, any calculations carried out, the results obtained and comments / conclusions. The lab book will be evaluated in order to verify the understanding of the experiments carried out and the ability to evaluate the results obtained. The laboratory notebook can be drawn up using normal writing software and must be sent to the teacher by e-mail at least 10 working days before the date on which the oral exam is scheduled. Maximum points: 6.
The final grade of the exam will be given by the sum of the score obtained in the oral exam and that obtained from the evaluation of the laboratory notebook.
The results of the exam are published on the ESSE3 portal (https://unipr.esse3.cineca.it/Home.do) within a reasonable time compatible with the number of students enrolled or in any case within 10-15 days from the date of the exam.
The grade obtained in the laboratory module will account for 50% of the final grade of the integrated course.
Lessons frequency is not mandatory, although strongly encouraged.
Compatibly with the evolution of the epidemiological emergency COVID-19, the lessons will be in attendance with registration of the same through the Microsoft Teams platform and uploading to the Elly page of the course, together with the teaching material.
Lab experiments are mandatory: the student will be admitted to the final examination only if he/she has attended all the lab experiments (for well documented reasons, failure to participate in one of the foreseen lab experiments would be accepted).