HSI2007 Food Information PDF

Introduction Week 1  Where do you get your information on Food from? There is nothing wrong with having an opinion. But the opinion has to be formed with considerations of facts. Facts help form an informed opinion and this leads to an informed decision....

Introduction Week 1  Where do you get your information on Food from? There is nothing wrong with having an opinion. But the opinion has to be formed with considerations of facts. Facts help form an informed opinion and this leads to an informed decision. Informed Informed Facts Opinion decision  Information about food Print and Media Site of purchase Online articles Research papers (eg. Supermarket) Overall display Online conversations and posts Conversations in-person Product information Advertisements and shows Newspapers and books What do you pay attention to on a food package?  Information Facts What do you think are the main types of misinformation about food? Informed Informed Facts Opinion decision Information about food could sometimes be mis-information. How do we tell? Health Safety Taste Cost & Sustainability Convenience Knowing about Food 1. Understand why misinformation on food exists Reasons Methods 2. Learn to interpret nutrition and health information systematically and critically Based on reliable sources of information Based on types of experimental study designs Based on and understanding of existing knowledge Why? Motivation for Food Misinformation #1: Profit eg. sale of products by lobbyists, internet traffic Why? Motivation for Nutrition Misinformation #2: Personal beliefs Health gurus, faith healers, some nurses or doctors Promotion of health supplements without economic interest. May hold on to theories and beliefs even after they have been disapproved or not scientifically substantiated. Why? Motivation for Nutrition Misinformation #3: Lack of understanding News reporters Lack understanding of subject to interpret and report research correctly. How? Method #1: Endorsements from “medical experts”, stars, famous sports man. How? Method #2: Exploiting misconceptions on sources of reliable information. Some people tend to believe certain avenues of information. Exploiting misconceptions on understanding of information. Vitamins, minerals, herbs etc are harmless. How? Method #3: Saying what they want to hear May offer solutions to problems with few or no solutions in orthodox health care. Individuals seeking alternative solutions to health care. How? Method #4: Science as a marketing tool Highly questionable claims that may sound scientific and true. Examples: Miraculously, The only product to use, No side effects, World’s best, Natural, FDA approved Individuals may lack the knowledge and skills to evaluate product claims. https://www.hsa.gov.sg/consumer-safety/articles/false-and-misleading-stem-cell-claims-made-on-supplements Baloney detection toolkit revisit Online article from Online article from Research article other websites Newsweek How reliable is the source of the claim? Source Does the source make similar claims? Have the claims been verified by somebody else? Science Does this fit with the way the world works? Has anyone tried to disprove the claim? Where does the preponderance of evidence point? Is the claimant playing by the rules of science? Is the claimant providing positive evidence? Does the new theory account for as many phenomena as the old theory? Are personal beliefs driving the claim? Statement Source Where did I read/hear this? National Kidney Foundation Consensus Singapore Nutrition and Dietetics Association Consensus Singapore Food Agency Health Promotion Board Consensus Health Sciences Agency National Environment Agency Factually Single opinion Consensus Increasingly, government website related to health has taken a pro-active stance to educate consumers about the safety and generally efficacy of health supplements. https://www.hsa.gov.sg/consumer-safety Source Peer-reviewed Scientific Journals Indexed research journals on journal search engines such as PubMed www.ncbi.nlm.nih.gov/pubmed or ScienceDirect https://www.sciencedirect.com/ Googling a research topic does bring you to some Pub-med a research topic brings you to 35,422 peer- articles. But it also brings you up to 91,800,000 other reviewed research articles and reviews. things! Sentence Cultivate an awareness of what you are reading. Identify and scrutinize the claim(s).  eg. may prevent, will prevent, may cure, will cure Is it a Fact or an Opinion?  eg. study results show, an expert predicts Survey results show that 75% of consumers believe that their fat intake should be as low as possible. 90% of consumers believe that fat is not needed for a healthy diet. Experts indicate that most consumers believe that their fat intake should be as low as possible and that fat is not needed for a healthy diet. Science “Everything they try to sell me is based on research” “It’s been proven” “Everything I read about is based on research and supported by experts” Methods of Science Established Science Ongoing Science No Science Pseudo-Science Pseudo-Science Because everyone claims they have ‘science’, one must be able to tell what is real science versus fake science. Or no science. A guide on: Common types of research papers Case report or case series A detailed and descriptive report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient. Opinion Points of view and appraisals of events, published work, and controversial topics. Original Research Articles Scientific studies that are in-vitro, cell lines, animal studies or human trials. Review A survey of previously published scientific studies on a topic. Provide a critical evaluation or overview of the data available from existing studies. No new experimental results presented. Systematic reviews A review of the evidence on a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant scientific studies. Meta-analysis A meta-analysis is a statistical analysis that combines the results of multiple scientific studies from a systematic review. Data is extract and analyze data from the studies that are included in the systematic review. Vitamin D & Inflammation A guide on: How to use a research paper to inform yourself about food and health? Components Description Use Title The essence of the paper, summarized in one line. Quick view on whether the research is potentially relevant to your question. Abstract A short summary to find out the important points of the paper, Summary of all you need to know about the research. This is usually without having to actually read the paper. the section we read most often. Introduction Provides the background information to understand why the Tells you why the research is important. described experiment was conducted. Methods Describe all experimental procedures, including controls. Allow you to critically evaluate the research design eg. type of human study, statistical analysis done etc Results Summarize general trends in the data, usually without too much Allow you to examine the data described in the abstract. Ensure interpretation. consistency of results and no over-reporting. Complete scientific understanding of the data is not always necessary for a layman. Discussion or Analyze the data and relate them to other studies. Suggest Tell you whether the results agree or disagree with what is already Conclusion future work. known or reported. Declaration of Most journals require that authors to disclose any conflicts of Always good to know whether the authors may potentially benefit conflict of interest related to the research. from the outcomes of the study eg. employees of a company selling interest (COI) the product. A COI does not mean that the results are invalid. Read more on the description of parts of a research paper at : https://researchguides.library.vanderbilt.edu/c.php?g=69346&p=831743 Deconstructing Food Methods of Science (Human Studies) Dr. LIU Mei Hui Department of Food Science and Technology Learning Objectives 1. Evaluate health and nutritional information systematically and critically 2. Describe the limitations of various study designs used in food and nutrition​  Pyramid of Scientific Evidence of Food and Health ​ Human studies provide direct evidence of benefits or harm Results from human studies always carry more weight Opinions and reviews do not generate new data The Methods of Science Important in examining effect of foods or nutrients on humans Correlation Cause-and- effect  Epidemiological Studies Observational studies Subjects under free living conditions with no alterations Reveals correlation  Types of Epidemiological Studies Cross-Sectional Case-Control Cohort All healthy Control (Healthy) Case (Disease) Follow healthy subjects into the future and collect lifestyle data Checking of subjects’ Present snapshot of population past medical history Data used to establish correlations  Experimental Studies Involves external intervention in a controlled manner Comparison between experimental and control groups Demonstrates cause-effect relationship Placebo Intervention  Experimental Study Design Randomization Single-Blinded Placebo Control Control Intervention Vitamin X Placebo Participants randomized using baseline measurements  Experimental Study Design Randomization Double-Blinded Placebo Control Control Intervention Vitamin X Placebo Participants randomized using baseline Some scientists still aware, but are not involved in measurements data collection  The Placebo Effect Change in health or perceived health due Which is a good to the expectation of a treatment placebo? producing an effect Even taking a pill with nothing in it can result in a measurable effect Good placebos are identical to actual treatment in every characteristic  Placebos in Nutrition Research No good placebo for whole foods or entire diet plans What would be a good placebo for these? Perfect nutritional intervention study not always possible Pyramid of Scientific Evidence of Human Studies Systematic Re-analysis of related groups of intervention review & meta-analysis studies or observational studies. Reveal cause-effect relationships. Gold standard is a Intervention study randomized, placebo controlled, double-blinded intervention. Observational studies reveal correlation Cohort study Gold standard is a cohort study Case control study Cross sectional study Case report or case series Summary Types of study designs (Observational vs Intervention) The Placebo Effect Limitations of nutritional research Deconstructing Food Food Components (Macronutrients) Dr. LIU Mei Hui Department of Food Science and Technology Learning Objectives Describe the general nutritive compositions of foods Relate the nutritive composition of foods to effects on health Nutrients  Carbohydrates Major source of energy for people throughout the world Simple Sugars Complex carbohydrates Complex carbohydrates Eg. Mono- and Di- (digestible) (non-digestible) saccharides Eg. Polysaccharide: Starch Eg. Polysaccharide: Fiber ~ 0-2 Calories per 4 Calories per gram 4 Calories per gram gram  Carbohydrates High in simple sugars and digestible High in simple sugars, digestible complex complex carbohydrates carbohydrates and fiber (undigestible complex carbohydrates)  Simple Sugars Mono-saccharides Di-saccharides Glucose Sucrose Fructose Lactose Galactose Maltose Should we avoid all sweet foods? Sucrose Glucose & Fructose Naturally present Artificially added Naturally present Artificially added High fructose corn syrup (HFCS) is a liquid mixture of two mono-saccharides, 55% fructose and 45% glucose. Simple Sugars and Health High sugar intake = adverse effects on health? Excess calorie Tooth Decay Associated with chronic diseases intake Foods with added sugars are typically energy dense Complex Carbohydrates Polysaccharides – contains many units of saccharides Body contains enzymes to Starch – long chain of glucose units digest starch and release glucose units for energy Salad Bowl Not all can be digested by the Low carbohydrates, or body (e.g. dietary fiber) and used Low simple carbohydrates? as energy Fried Foods or Seafoods? ​ “You have high bad Which foods to avoid to not cholesterol. Try and have high cholesterol? avoid foods that gives you high cholesterol.” Dietary Fats Fat obtained from foods in our diet Different types – saturated fatty acids & mono/poly- unsaturated fatty acids Provide energy of 9 calories per gram Source: Composition of triglycerides found in various foods. http://www.accountax.us/Secondary%20Education%20Health%20 Education%20I%20Chapter%205%20The%20Lipids%20Triglycerides,%20Phospholipids.pdf Accessed on 30 July 2024 Triglycerides Glycerol + 3 Fatty Acids = Triglyceride Most common form of fatty acids in foods Fatty acids can be a combination of saturated or mono-/polyunsaturated fatty acids Digested into two free fatty acids & a monoglyceride  Fatty Acids Saturated Unsaturated Liquid at room temperature Carbon chains saturated with (e.g. plant oils) hydrogen atoms Solid at room temperature (e.g. animal fats) Points of saturation  Hydrogenation Mono-unsaturated Fatty Acid Unsaturated fatty acids prone to oxidation that produces off-flavours Process that increases degree of saturation of unsaturated fatty acids Trans fatty acids processed like saturated fats, but interrupt Saturated Fatty Acid Trans Fatty Acid biological processes Dietary Cholesterol Type of dietary fat linked to heart health HO Dietary Cholesterol Form of fat with no calories One-third of cholesterol is found in animal products Remainder produced by the liver  Blood Cholesterol Refer to lipoproteins that carry Typical cholesterol in the bloodstream Lipoprotein Source: Whitney and Rolfes, Typical Lipoprotein structure. https://www.docdroid.net/de4NtFu/understanding- nutrition-by-eleanor-noss-whitney-sharon-rady-rolfes-pdf Accessed on 5 August 2024 Low-density Lipoprotein (LPL) aka. bad cholesterol LDL HDL Density Low High High-density lipoprotein (HDL) Function Deliver lipids Scavenge cholesterol aka. good cholesterol around the body to deliver back to the liver Heart Attack ↑ ↓ Distinct from dietary cholesterol Risk High Cholesterol? Liver produces more LDL Which foods to avoid to transport excess fat if you have high bad throughout the body cholesterol (LDL)? Lower saturated fat intake = lower LDL levels No strong correlation between dietary cholesterol and LDL levels  Proteins Animal products and their derivatives (e.g. Plant products and their derivatives (e.g. tofu) milk, cheese) contains complete proteins. are lower in saturated fats. However, some Except seafood, animal products are also plant sources contains incomplete proteins. higher in saturated fats. Proteins and their Functions Provide 4 calories per gram, but not preferred energy source Amino acids instead used to maintain body functions Various proteins have different roles Protein Amino Acids Peptide Chain e.g. Enzymes as they are comprised of different amino acids and lengths Essential & Non-Essential Amino Acids Essential Amino Acids Nonessential Amino Acids Essential Amino Acids: Histidine Alanine Isoleucine Arginine Cannot be made by the human Leucine Asparagine body in sufficient amounts Lysine Aspartic Acid Methionine Cysteine (obtained from diet) Phenylalanine Glutamic Acid Threonine Glutamine Non-essential Amino Acids: Tryptophan Glycine Valine Proline Can be readily produced by the Serine human body Tyrosine Protein Quality Presence of essential amino acids determines quality Animal products contain all essential amino acids Plant proteins sometimes lack certain essential amino acids  Complementary Protein Sources By consuming a combination of plant proteins, a diet can still consist of all essential amino acids Source: Whitney and Rolfes, Typical Lipoprotein structure. https://www.docdroid.net/de4NtFu/understanding- nutrition-by-eleanor-noss-whitney-sharon-rady-rolfes-pdf Accessed on 5 August 2024 Summary Macronutrients in our diet and their roles Effect of macronutrients on human health Deconstructing Food Food Components (Micronutrients) Dr. LIU Mei Hui Department of Food Science and Technology Learning Objectives Describe micronutrients and their general properties Discuss the consequences of selected micronutrient and their effects on health  Vitamins Only consist of vitamins A, Fat-Soluble Vitamins Water-Soluble Vitamins D, E, K, C, and B complexes Vitamin A (retinol) Thiamin (B1) Cyanocobalamin (B12) Natural and required by the Vitamin D (1,25-dihydroxy-cholecalciferol) Riboflavin (B2) Biotin human body Vitamin E (tocopherol) Niacin (B3) Pantothenic acid Supplements may be Vitamin K (phylloquinone, menaquinone) Pyridoxine (B6) Choline misleading and call their active ingredient “vitamins” Methionine Folate (folacin, folic acid) Vitamin C (ascorbic acid)  Vitamin D HO Can also be synthesized by the body H by exposure of skin to UV HO UV H Toxicity of vitamin D usually not due to Dietary Cholesterol Vitamin D3 synthesis by the body but due to supplementation Encourages absorption of calcium and phosphorus from our diet Deficiency leads to weakening of bones (rickets) Source: Normal bones compared to rickets. https://nigerianscholars.com/tutorials/animal- systems-intro/rickets/ Accessed 30 July 2024  Vitamin C Enhances immunity and keep connective tissues healthy Deficiency can occur quickly and cause scurvy Supplements often provide vitamin C in large excess that is excreted through urine Source:. Vitamin C supplement, LAC Singapore https://www.lac.sg/en/vitamins-and-supplements_letter- vitamins/lac/triaction-c-500---timed-release-01404250.html Source: Philippa Matthews. Vitamin C requirements. Accessed 30 July 2024 https://slideplayer.com/slide/5741428/ Accessed 30 July 2024  Minerals Obtained from diet but do not provide energy 15 essential minerals obtained from diet Source: Structure of haemoglobin https://chemistrytalk.org/hemoglobin-in- biochemistry/ Accessed 30 July 2024 Function as co-factors and each have highly specific functions Iron in Haemoglobin  Heme vs Non-Heme Iron in Foods Heme iron is more easily absorbed Vegans need more vegetables or iron supplements as nonheme iron is not easily absorbed  Minerals in the Body Different minerals are present in different quantities in the body Divided into major and trace minerals Source: aimon, Minerals in a 60 kg person. https://www.slideserve.com/aimon/chapter-8-water-and-minerals/ Accessed 30 July 2024  What makes food healthy? Energy-dense Nutrient-dense Macronutrients usually used in context of energy Micronutrients usually used in context of nutrients High in calories per High in nutrients relative weight of food to calorie content  What makes food healthy? Energy-dense Nutrient-dense Empty Calories High in calories per High in nutrients relative Excess calories relative weight of food to calorie content to nutrient content  Applying the concepts Values Per 100g Full cream milk Milk tea with pearls Energy 65 kcal 79 kcal Protein 3.2 g 0.1 g Healthiness of foods can Total fat 3.4 g 3.2 g be evaluated by Saturated fat 2.1 g 2.94 g describing its calories Carbohydrate 4.6 g 12.4 g and its nutrient density Calcium 93mg 10mg Potassium 114mg 52mg Vitamin A 40mcg 0mcg Thiamin 0.03mg 0mg Empty calories Summary Micronutrients in our diet and their roles Deficiency of micronutrients on human health What makes food healthy Credits Producer Dr. LIU Mei Hui Production Assistants Mr. NEO Teng Whay Blended Learning Team Enabler Mr. Benedict CHIA Mr. Terence LIM Visuals and Graphics used from Freepik and Canva.com The proof is in the pudding What should we choose to eat? Week 3 Lesson outline of Week 3 Topic Lesson Summary of Week 2 Digestion and absorption of nutrients Putting everything together Project Work Instructions Summary of Week 2 Week 3 A meta-analysis is broadly a re-analysis of data consolidated from multiple relevant human studies. Cross-sectional Case- Control Cohort Intervention Healthy Check Population subject’s Healthy Randomized history to 2 groups ‘Case’ ‘Control’ Follow subject’s Treat- Heart No heart Placebo disease disease ment Eg. People with heart disease are associated Eg. 5% of healthy Eg. A daily intake of Eg. 5% of the with consumption of subjects develop heart 250mg PUFA causes a population has less polyunsaturated disease over time. The reduction in blood heart disease. fatty acids (PUFA), intake of PUFA is triglycerides levels of compared to people correlated to heart treatment group by without heart disease. disease. 15%. Associations Cause -Effect How do you describe a good placebo? Digestion and Absorption of nutrients Week 3 Digestion and absorption of macro-nutrients Macronutrients refers to carbohydrates, proteins and fat in the diet Carbohydrates Digestible, complex carbohydrates: Starch found in bread Carbohydrates Non-digestible, complex carbohydrates: Fiber found in vegetables Protein Fats Carbohydrates Chicken Patty Ingredients: Simple carbohydrates: Simple Sugars Chicken Leg (88%), Salt, Sugar, White Pepper, Dry Parsley, used as ingredients for patty Water, Bread Crumb, Egg white, E451 Triphosphate Hydrolysis is the basic chemical process in digestion Specific digestive enzymes in our body helps hydrolysis to occur Carbohydrates digestion by carbohydrase enzyme e.g. sucrase, amylase Hydrolysis + Water + sucrase Sucrose enzyme 1 Glucose 1 Fructose (A Di-saccharide consisting of 1 Glucose and 1 Fructose) Hydrolysis + Water Amylase Many Starch enzyme (A Poly-saccharide consisting Glucose of many Glucose molecules) Hydrolysis is the basic chemical process in digestion Specific digestive enzymes in our body helps hydrolysis to occur Protein digestion by protease enzymes eg. pepsin, trypsin aa aa aa aa Hydrolysis aa aa + Water aa + aa aa Protease aa aa aa Amino Small aa Acids peptides aa Proteins (polypeptides) AA: Amino Acid Hydrolysis is the basic chemical process in digestion Specific digestive enzymes in our body helps hydrolysis to occur Fat digestion by lipase enzymes Glycerol Glycerol FA Hydrolysis + Water Lipases FA + FA FA FA FA 1 monoglyceride Triglyceride 2 Free Fatty acid FA: Fatty Acid Carbohydrates Monosaccharides eg. Glucose, Fructose, Galactose Disaccharides eg. Sucrose, Lactose, Maltose 2 Monosaccharides Polysaccharides (digestible) eg. Starch Many Monosaccharides Polysaccharides (not digestible) e.g. Fiber Remains Polysaccharides Proteins Amino acids + Small peptides Proteins eg. Enzymes Fats Mono-glyceride + 2 Fatty Triglycerides acid Glycerol + 3 Fatty acid Imagine a food or drink in your mind. What is the main compositions? Enzymes in the digestion of macro-nutrients Mouth: Amylase Stomach: Pepsin Large Intestine: Small Intestine & Pancreas: No digestive enzymes Pancreatic amylase produced by us Intestinal enzymes e.g. sucrase Lipase Proteases e.g. trypsin Digestion and absorption of macro-nutrients Mouth Mechanical crushing o Chews and mix food with saliva Digestion o Carbohydrates- Amylase breaks down starch o Fats- Negligible amount of lipase breaks down some fats o Protein- Does not get broken down o Absorption o None Digestion and absorption of macro-nutrients Change in pH (~pH 2) by gastric juice Activate protein digestive enzyme- pepsin Denaturing food proteins Destroy many bacteria in food Digestion Carbohydrates- Negligible amounts Stomach digested Fat- Negligible amounts digested Protein- Gets broken down by pepsin Digestion and absorption of macro-nutrients Carbohydrates Digestion by pancreatic amylase on starch and intestinal enzymes (eg. sucrase, lactase, maltase) break down disaccharides into monosaccharides Simple sugars gets absorbed Fat Emulsification by bile for lipase digestion Digestion by pancreatic and Small intestine + intestinal lipase into fatty acids and Pancreas, Liver, Gall bladder glycerol Absorption occurs Protein Break down by trypsin into amino acids or small peptides Amino acids are absorbed Digestion and absorption of macro-nutrients Carbohydrates Undigested carbohydrates partly broken down by intestinal bacteria Fat Large intestine Some fatty material carried out as waste Protein Carries undigested protein out as waste Digestion and absorption of micro-nutrients and other components found in food Micro-nutrients are vitamins and minerals in our diet Most do not require hydrolysis by digestive enzymes and are directly absorbed eg. Vitamin C Optimal absorption is dependent on the chemical form it is found in food eg. Iron from meat is better absorbed than iron from vegetables Some are absorbed in an inactive form and converted to an active form in the body eg. Vitamin D Some small molecules found in food are also directly absorbed eg. Alcohol Digestion and absorption Digestion 1. Mouth 2. Stomach 3.Small 4. Large intestine intestine Carbohydrates Yes* No Yes No (Fiber, yes) Proteins No Yes* Yes No Fats No No Yes* No Water NA NA NA NA Alcohol NA NA NA NA * Denotes location where macronutrient is first digested Major site of absorption Absorption Mouth Stomach Small intestine Large intestine Carbohydrates No Yes ie. glucose Yes No Proteins No Yes ie. amino acids Yes No Fats No No Yes No Water No Yes Yes Yes Alcohol No Yes Yes No Putting everything together Week 3 A guide: Proteins are large macromolecules which have a vast array of functions in the organisms. Structural proteins that makes our hair and nails, digestives enzymes which break down food, hemoglobin which carry oxygen in blood are some examples of proteins in our body. Proteins have specific function at its quaternary structure. However, a change in temperature or pH will disrupt this quaternary structure. Once this structure is lost, function is also lost. Thus, digestive enzymes, like all proteins, digest specific compounds and works only at specific conditions in the digestive tract eg. acidic pH of stomach for pepsin. Photo: https://theory.labster.com/protein-structure/ Should you buy that supplement? Meta-analysis What is the conclusion? Observation No Meta-analysis Is there a number of studies done? Human studies Super Supplement Meta-analysis What is the conclusion? No human studies Intervention No Meta-analysis Is there a number of studies done? Function dependent on full structure Human Studies What type? Macronutrient Absorption Function not dependent No human studies on full structure No absorption Human Studies What type? Digestion of Super Absorption Supplement Micronutrient No human studies No absorption Human studies What type? Absorption Phytochemical No human studies No absorption Deconstructing Food Physics and Chemistry in Food Dr. LIU Mei Hui Department of Food Science and Technology  Food Technologies Source: Siegrist & Hartmann, Consumer acceptance of novel food technologies (2020). Nature Food, 1, 343. Used with permission. © Nature Food Learning Objectives 1. Identify key forms of heat transfer used in different cooking methods 2. Describe Maillard reaction process 3. Evaluate importance of the Maillard reaction in different food context  Bread Digestible, complex Sensorial aspects carbohydrates such as starch Chicken Patty Ingredients: Chicken Leg (88%), Salt, Sugar, White Pepper, Dry Parsley, Water, Bread Crumb, Egg white, E451 Triphosphate Chicken Patty Vegetables Protein, fats and simple Non-digestible, carbohydrates like complex carbohydrates simple sugars found such as fiber found Catching Fire Written by Prof. Richard Wrangham Anthropologist & primatologist Cooking caused the extraordinary transformation of our ancestors from apelike beings to Homo erectus Source: Catching Fire: How Cooking Made Us Human. https://www.amazon.co.uk/Catching-Fire-Cooking-Made- Human/dp/184668286X. Accessed on 11 Aug 2024 Effects of Food Processing Sensory quality Microbial quality Nutritive value Main Impact of cooking on Food Microbial quality Nutritive value Sensory quality Is Cooking an experiment or an art? Food Recipe Experimental Protocol Cookware Lab Apparatus Ingredients Reagents Instructions to follow Instructions to follow Outcome changes when variables change Outcome changes when variables change Need to control variables to ensure Need to control variables to ensure consistent results consistent results  Protein Fats + Acids Oxygen Carbohydrate Vitamins Minerals Water Food Flavor Color Texture Food Compositions and Cooking Source: J. Potter (2010). Cooking for Geeks: Real Science, Great Hacks, and Good Food (2nd ed, O Reilly Publishing). Used with permission. © O Reilly Publishing Food Compositions and Cooking Source: J. Potter (2010). Cooking for Geeks: Real Science, Great Hacks, and Good Food (2nd ed, O Reilly Publishing). Used with permission. © O Reilly Publishing Denaturation Accessibility Digestibility Nutritional value Source: J. Potter (2010). Cooking Source: J. Potter (2010). Cooking for Geeks: Real Science, Great for Geeks: Real Science, Great Hacks, and Good Food (2nd ed, O Hacks, and Good Food (2nd ed, O Reilly Publishing). Used with Reilly Publishing). Used with permission. © O Reilly Publishing permission. © O Reilly Publishing Food Compositions and Cooking Source: J. Potter (2010). Cooking for Geeks: Real Science, Great Hacks, and Good Food (2nd ed, O Reilly Publishing). Used with permission. © O Reilly Publishing Cooking Microbial Safety Food Compositions and Cooking Sensorial Cooking quality Source: J. Potter (2010). Cooking for Geeks: Real Science, Great Hacks, and Good Food (2nd ed, O Reilly Publishing). Used with permission. © O Reilly Publishing Conduction Heat is transferred by direct contact Energy passed from one molecule to another in the solid space from a hotter region to a colder region Convection Heat is transferred via movement of a heated material against a colder material Natural Forced No mechanical means to Mechanical means such as aid convection a stirrer to aid convection Wet Heat Dry Heat Boiling Baking Steaming Radiation Heat is transferred by electromagnetic radiation without any physical medium Grilling uses infra-red radiation while microwave uses dielectric radiation Summary Conduction Convection Radiation Description Heat passes by direct Heat passes via movement Heat is transferred via contact between two of a heated material electromagnetic radiation materials against a colder material Example Steak on pan, pan on stove Hot water, hot air Infrared radiation from charcoal Dielectic heating from microwave oven Uses Searing Dry heat: Grilling Pan-frying Baking Microwaving Roasting Deep-fat frying Wet heat: Boiling Braising Steaming Simmering Key Reactions during Heat Transfer Protein Denaturation Maillard Reaction Protein Denaturation Denaturation Cooling Native Denatured Conjugated Different proteins denatures at very specific and different temperatures Maillard Reaction Responsible for the development of flavor, aroma and color The Maillard is, by far, the most widely practiced chemical reaction in the world,” Chemistry Nobel Prize winner Jean-Marie Lehn Maillard Reaction A form of non-enzymatic browning that is initiated by a chemical reaction between a reducing sugar (carbohydrate) and an amino acid (protein), upon the addition of heat Enzyme Specific temperature and pH Maillard Reaction Step 1 Initiated by a condensation reaction between a reducing sugar (carbohydrate) and an amino acid (protein) Examples of reducing sugars Examples of amino acids Reactive carbonyl group Cysteine Nucleophilic amino group Glucose Fructose Lysine Maillard Reaction Step 2 Followed by a series of simultaneous and consecutive chemical reactions with intermediate products Aldehydes Aldols Amadori or Heyns Strecker degradation Aldol and aldehyde-amine Melanoidins rearrangement Sugar dehydration condensation Sugar fragmentation Formation of heterocyclic nitrogen compounds Source: Food Chemistry – The Maillard Reaction, Compound Interest. https://www.compoundchem.com/2015/01/27/maillardreaction/. Accessed on 31 July 2024 Impact of Maillard Reaction Maillard reaction products are often associated with distinct flavor/ aroma characters Melanoidins Aldehydes Flavor (brown nitrogen- Aldols Aroma containing high molecular weight pigments) Colored compounds Impact of Maillard Reaction More flavor compounds arise from further interactions between Maillard reaction and thermal degradation of lipids + Intermediate molecules Distinct flavors Lipids Impact of Maillard Reaction Amount and rate of browning are dependent on food matrix composition and reaction conditions Examples of compounds formed from Maillard Reaction Source: Robert J. McGorrin. The Significance of Volatile Sulfur Compounds in Food Flavors (2011). American Chemical Society. Used with permission. © American Chemical Society Source: Samar M. Bassam, Clarice Noleto-Dias, Mohamed A. Farag. Dissecting grilled red and white meat flavor: Its characteristics, production mechanisms, influencing factors and chemical hazards (2022) Food Chemistry, 371, 11319. Used with permission. © Food Chemistry Impact of Maillard Reaction Type of amino acid significantly affects the resultant flavor/ aroma Amino acid Odour compounds Odour description Leucine 3-methyl butanal Burnt, caramel Phenylalanine Phenylacetaldehyde Green, flowery, almond, bitter Proline Pyrrolidine, 1-pyrroline Fruity, bitter, bread-like aromas Methionine Methional, methanethiol, 2-propenal Vegetable-like aromas, potatoes Cysteine Mercaptoacetaldehyde, ammonia Sulfur, meaty Adapted from Newton et al. (2012) and Nursten (2005). Impact of Maillard Reaction Generation of contribute to browning of foods Reaction conditions Influence Amount of Melanoidin produced pH Type of Food Impact of Maillard Reaction Desirable Undesirable Desirable roasted, nutty and Flavours generated from Maillard burnt flavours/ aromas reaction perceived as off-flavours Browning increases product Susceptible to Maillard Reaction appeal during thermal processing (e.g. Ultra high temperature processing) Impact of Maillard Reaction Loss of nutrients Destruction of essential amino Decreased bioavailability of amino acids, decrease in protein quality acids and minerals Affects dietary protein utilization Affects absorption of iron, phosphorus, magnesium and calcium Impact of Maillard Reaction Generation of potentially harmful substances Protein rich foods Starch rich foods Heterocyclic aromatic Acrylamide amines (HCA) Impact of Maillard Reaction Generation of potentially harmful substances Heterocyclic aromatic amines (HCA) Impact of Maillard Reaction Generation of potentially harmful substances Associated with cancer, diabetes, Acrylamide Alzheimer’s disease, etc. Heterocyclic aromatic amines (HCA)  Wok Hei Convection Conduction Source: Lan Lam, Two-Zone Cooking (2010) https://www.cooksillustrated.com/articles/2189-the-science-of-stir-frying-in-a-wok. Accessed on 31/7/2024 Further Thinking How does food change when we cook them? ​ When is the Maillard reaction a good thing and when is it not a good thing? Deconstructing Food Microbiology in Foods Dr. LIU Mei Hui Department of Food Science and Technology Learning Objectives 1. Explain role of microorganisms in food 2. List properties of probiotics 3. Differentiate between Food Infection vs Food Intoxication and their implications on Food Safety Microorganisms in Foods Carbon sources Nitrogen sources Microorganisms in Foods Microorganisms in Foods + Salt Sauerkraut For consumption Microbial Spoilage Food discarded + Food wastage  01 02 03 04 Fermentation Spoilage Probiotics Pathogens microbes microbes Involves the Mostly beneficial Bacteria, molds Mostly pathogenic use of molds, and health- and yeasts that bacteria and viruses yeasts and promoting causes food that causes food- bacteria bacteria spoilage borne illnesses/ diseases Fermentation microbes Food Fermentation Beneficial microorganisms are Taste intentionally introduced to change the Aroma Nutritional Quality taste, aroma or nutritional quality of foods Some foods use multiple microorganisms (can be added sequentially/together) Encompasses a series of metabolic processes which break down large e.g. Kombucha SCOBY uses a Symbiotic molecules into simpler compounds Culture of Bacteria and Yeasts​ Probiotics They are live microorganisms which when administered in adequate amounts confer a health benefit on the host (humans, animals) in terms of gut or immunity. Yakult is a premium probiotic cultured milk drink that contains the specially cultivated beneficial bacteria known as Lactobacillus casei strain Shirota. Each little bottle of Yakult is packed with more than 10 billion L. casei strain Shirota, enough to replenish the friendly bacteria in your digestive tract. Source: Yakult, Wikimedia commons. CC BY-SA 4.0 Fermented foods as a Source of Probiotics Not all the microbes used in fermentation have known health benefits Microbes in food products might not be considered as probiotics if they are killed Beneficial under high heat processing steps Microorganisms Harmful Microorganisms Prebiotics and Synbiotics Prebiotics Synbiotics Non-digestible substances that provide a Involves the preparations of probiotics and beneficial effect on the host by selectively prebiotics to create a synergistic effect stimulating growth of probiotic bacteria Potentially have the best health effect Most are carbohydrates – e.g. inulin, an oligosaccharide Rotten Foods vs Fermented Foods Food Rot Fermentation Occurs when there is uncontrolled proliferation Choice of microorganisms and fermentation of undesired microorganisms due to various conditions are carefully designed and controlled reasons such as improper storage conditions Change in fermentation or post-fermentation Some microorganisms are harmful and cause conditions can cause fermented products to rot foodborne illnesses Food Spoilage Food spoilage may be due to non-microbial means It is a relative term Buttery aroma Gas (CO2) Holes Lager beer Dairy products Cheddar cheese Emmentaler Food Spoilage Due to the changes in original nutritional value, texture and flavor Microbial spoilage Chemical spoilage - Presence of gas, off odor, - Presence of oxidation off-taste and mold and off-odor - Possess a potential safety risk - No safety risk Biochemical spoilage Physical spoilage - Involve enzymatic reactions, - Examples include creaming off discolorations and off-odor in whole milk & wheying off in from lipid breakdown yogurt (Phase separation) - No safety risk - No safety risk Food Poisoning A foodborne illness that includes both food infection and food intoxication Food infection - Due to ingestion of foods containing pathogens - Pathogens can grow in humans and produce toxins to cause illness - Largely prevented by cooking as most microbes are destroyed by heat Food intoxication Prevention - Due to ingestion of foods - Personal hygiene containing microbial toxins - Food handling practices - May not be preventable by - Sufficient cooking cooking as some toxins are heat resistant Source: Chang, Spize food poisoning: 6 types of pathogens found, CNA https://www.channelnewsasia.com/singapore/spize-salmonella-food-poisoning-6-pathogens-river-valley-912126. Accessed on 13 Aug 2024 Case Study Food Poisoning​ Microbes​ Common Food​ Actual source of contamination in Spize case​ Food infection Salmonella​ (2 types)​ Raw and unrefrigerated food​ Fried rice, door handle​ by bacteria Faecal Coliforms​ Generally in faecal matter​ Fried rice, chopping board, knife​ CamplylobacterJejuni Raw food and faecal matter​ Food handler​ Food infection Bacillus cereus Cooked food​ Fried rice​ by bacteria Food intoxication *Its toxins are heat resistant​ by its toxins Food infection Norovirus Contaminated surfaces and food​ Food handler​ by virus  A total of 315 people fell ill after attending five separate events at the Grand Ballroom held across 3 days “Norovirus was found on multiple surfaces, including carpet, tables, chairs, unused tablecloths, cutlery and drinking glasses.​ I​ nterviews that were conducted with the staff at Mandarin Orchard also revealed "improper cleaning of vomitus in the Grand Ballroom, and banquet servers had continued to work while ill.” Source: Chang & Choo, 175 food poisoning cases linked to 4 events held at Mandarin Orchard’s grand ballroom, Straits Time https://www.straitstimes.com/singapore/42-fall-ill-after-meal-at-mandarin-orchard-4-hospitalised. Accessed on 13 Aug 2024 Rules of Food Handling Good Personal Hygiene Good Food Adequate Cooking Handling Practices Summary Microbes can be introduced at any point as the food moves from farm to fork​ Intentionally (fermentation) vs unintentionally (contamination) Good (probiotics) vs bad (foodborne illnesses) Deconstructing Food Food Processing at Home and at Scale Dr. LIU Mei Hui Department of Food Science and Technology Learning Objectives 1. List down key effects of food processing 2. Explain concept of shelf-life 3. Based on the conditions used in food processing steps, explain general impact on food products The Food Industry The Food Industry Agriculture Production Food Production Provides fresh produce, minimally processed food or raw ingredients to produce other food products in Food Production Use of physical, chemical or biological means to convert raw food materials into consumable food products (ingredients or consumer products, pre-cooked or cooked forms) The Food Industry Source: Jacqueline H. Beckley, M. Michele Foley, Elizabeth J. Topp, J. C. Huang, Witoon Prinyawiwatkul (2007). Accelerating New Food Product Design and Development (1st ed, Blackwell Publishing). Used with permission © 2007 Blackwell Publishing and the Institute of Food Technologists Effects of Food Processing Microbial activity Sensory quality Nutritive value Shelf-Life extension of foods Raw or unprocessed foods are perishables. However, simple methods to process food, either at home or in the industry, have allowed foods to be safe to eat for longer and with less wastage. For example, tomatoes have a shelf-life of ~10 days. Bottled tomatoes have a shelf-life of 1-2 years. Nicholas Appert showed that cooking food in sealed bottles or cans can preserve the safety of food for a longer time. His method was easy and quickly adopted by many to extend the shelf-life of food products. However, Appert was never able to explain why it worked. It was only later on when Louis Pasteur showed that heat kills Nicholas Appert, bacteria. 1800s  Shelf-life includes microbial activity and sensory qualities Shelf-life extends to sensory qualities. Take for example Sensory quality also involves the sense of sound and rice. White rice can be stored indefinitely while brown texture. Potato chips that are not crispy is deemed rice only has a shelf-life of 6 months. This is because ‘stale’ or ‘lao hong’. There is no microbial issues or the bran layer is rich in lipids that can be oxidized and change in taste. Yet, it is also one of the quality which gives off an off-flavor. Consumers would not want to reduces the shelf-life of foods. consume it and thus brown rice has a lowered shelf life because of the loss in sensory quality. Improvement of digestibility Undesirable effects on Nutritive value of Foods Loss of certain nutrients – e.g. Vitamin C during processing Vitamin Fruits Legumes boiled 2-2.5 hours, drained Canned (%) Frozen (%) Dried (%) Vulnerable to most Vitamin C 50 70 20 65 processing methods Folate 50 95 50 30 Stable Choline 100 100 100 100 in many processing Vitamin B12 100 100 100 100 methods Source: USDA Table of Nutrient Retention Factors (2007), USDA. https://www.ars.usda.gov/ARSUserFiles/80400535/Data/retn/retn06.pdf Accessed on 14 Aug 2024 Apa  Food Processing Methods Physical Methods Thermal treatments Size reduction e.g. Milling (grain) Mild heat High heat Reduce temperature Blanching Sterilisation Chilling Pasteurisation (e.g.canning, UHT) Freezing Dehydration (e.g. spray drying) Baking & roasting Smoking Glossary of Physical Food Processes Physical Processes Description Blanching 70-100oC, 2-7 min Pasteurization 72oC, 15 sec, High-temperature short-time (HTST) Sterilization In-container sterilisation (canning) – 121oC/1 h Ultra-high temperature (UHT) process (liquid foods) – 135-142oC/2-5 sec Dehydration Heat to remove majority of water Baking, roasting Heated air Smoking Heated smoke Chilling Reduce food temperature to 0oC-7oC Freezing Reduce food temperature to below freezing point (