Nutrition and food chemistry

Learning objectives

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  • Created by: isabelle
  • Created on: 16-03-13 17:33

Minerals in food, combustion, ions, ionic bonding

  • Define oxidation
  • name minerals common in food, desirable and undesirable
  • explain combustion, name the reactions and producs
  • explain why minerals do not combust
  • define ionic bonding
  • describe the structure of ionic compounds (salts)
  • recognise the formula of a salf
  • calculate the amount of sodium from salt and vice versa
  • explain how to expermentally determine the mineral content in food
  • identify examples of minerals in food: as solutes, and as adjuncts to molecules (haemoglobin, caesin, chlorophyll
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Acids, weak acids, pH, neutralisation, moles

  • Define an acid
  • list the properties of an acid
  • recognise and sketch the carboxylic acid group
  • name examples of acids common in food and inorganic acids
  • Define and compare weak and strong acids
  • sketch a diagram of the pH scale with food examples accurately placed
  • Explain the relationship between H+ concentration and pH
  • Outline the nature and purpose of buffers and acidity regulators
  • Describe the process of neutralisation of an acid
  • Discuss the effect of pH on food: chemical reactions, enzymic reactions, individual chemicals, and microorganisms
  • define a mole
  • calculate mass of x moles, molarity of a solution 
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Water and food

  • Calculate the moisture content of foods from nutritional label information
  • Describe a method for the determination of moisture content in foods.
  • Describe the composition of water in terms of molecules, ions and hydrogen bondind.
  • Explain the nature of polarity and how it influnces the properties of water
  • Discuss how water interacts with the major  food components (ionic and covalent)
  • Explain the process of rehydration
  • Suggest why fats do not interact with water
  • Define water acitivity
  • Explain the concept of water availability
  • Define: solubility, solvent, solutes, solutions, hydrophillic, polar
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Water and food bond

  • Forecast the moisture content of foods
  • Describe a method for the determination of moisture content in foods
  • Describe the covalent bond in water
  • Explain the nature of polarity and how it influences the properties of water 
  • Discuss how water interacts with the major components 
  • Explain the process of rehydration
  • Suggest why fats do not interact with water 
  • Define water activity
  • Explain the concept of water availabilty 
  • List the minimum levels of water activity needed by a range of microorganisms
  • Concentration of solutions in moles, or g/100ml
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Carbohydrates, sugars: Monosaccharides

  • Name three carbohydrate rich foods
  • List the major properties of a number of carbohydrates
  • Suggest the carbohydrate content of a named food
  • List the chemical elements present in all carbohydrates
  • Classify carbohydrates as mono, di or polysaccharides
  • Name the major functional groups found in monosaccharides
  • Distinguish between pentoses and hexoses
  • Exlain the difference between D and L isomers
  • Explain the difference between reducing and non-reducing saccharides
  • Explain the reaction with Fehlings solution
  • Draw a simple representation of glucose structure 
  • Explain how the ring structure of a monosaccharide can be converted to the fisher proection form* (not on exam)
  • Distinguish between monosaccharides and sugar alcohols 
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Carbohydrates. Polysaccharides: Starch and fibre

  • Classify polysaccharidesaccording to function
  • Describe and draw a starch granule (see practical)
  • Draw simple models of amylase and amylopectin
  • Explain the action of iodine on starch molecules
  • Compare and contrast amylose and amylopectin
  • Compare and contrast amylose and cellulose
  • Describe the composition of fibre
  • Outline the stages in starch gelatinisation
  • Describe the effect of amylase enzymes on starch 
  • Describe the effect of acid on starch
  • Explain the structure and properties of three types of modified starch
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Lipids: Food fats and oils

  • List properties of lipids in foods
  • Name three sources of oils and fats
  • identify foods and food products high in fat
  • Explain the composition of food lipids
  • Sketch a free fatty acid
  • Sketch a triglyceride molecule eg triaglycerol
  • Name the molecules that triglyceride is formed from
  • Identify the functional groups/; carboxylic acid, alcohol, ester in lipid molecules
  • Identify fatty acids using short hand nomenclature eg C18:1^9
  • Name the 18 carbon fatty acids
  • Define saturated, unsaturated, mono-unsaturated and poly unsaturated, omega 3 in terms of fatty acid chemical structure
  • Distinguish between cis and trans fatty acid molecules
  • Explain the effects of cis/trans double bonds on fatty acid molecule shape
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Lipids: composition and melting

  • Explain the effects of cis/trans double bond and carbon chain length on fatty acid melting point 
  • Deduce the melting point of a triglyceride from it's fatty acid content
  • Discuss the triglyceride composition of a fat (lard) and an oil (olive oil)
  • Describe the melting range of a fat (lard,cocoa butter) or oil (olive oil)
  • Explain the plastic behaviour of fats
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Lipids: Rancidity and hydrogenation

  • Distinguish between hydrolitic rancidity and oxidtive rancidity in fats and oils
  • Name two agents of hydrolysis the reactants and the products
  • Define oxidation and reduction, and redox
  • List the reactants, products and conditions of oxidative rancidity
  • Describe the three stages of oxidative rancidity
  • Explain how peroxide value is used to monitor oxidative rancidity
  • Give examples of food processes that cause or delay oxidative rancidity
  • Explain why Oxidative rancidity is inevitable
  • Compare hydrolytic and oxidative rancidity
  • List the types of spread available eg butter, margerine
  • identify the reasons for processing (hardening) of oils to fats
  • Describe the process of hydrogenation, identifying reactions, conditions and products
  • Explain how hydrogenation raises the melting range of a food lipid
  • Discuss the undesirable effects of hydrogenisaton
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Proteins: structure

Identify main sources of protein in food.
Name the 5 elements found in all proteins
Sketch an amino acid.
Categorise the types of amino acid R group
Give a chemical property of each category
Describe the formation of a peptide bond
Name two agents of peptide bond hydrolysis
Sketch or describe a generic protein molecule
Define ”% amino acid composition” of a protein
Describe a method to determine protein content of food
Describe the four stages of protein structure, and the chemical bonding holding the structure together at each stage

Recognise the more complex structure and properties of proteins over carbohydrates and lipids; yet be aware of the common reactions of condensation and hydrolysis.

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Proteins: structure and properties

Describe the four stages of protein structure, and the chemical bonding holding the structure together at each stage. List the properties of protein in food. Contrast fibrous and globular proteins in terms of structure, solubility and role in food. (18) Explain the effect of pH on the solubility of proteins e.g. casein. Comprehend the effects of heat on the native shape and solubility of proteins e.g. on egg albumin, collagen, actin and myosin, casein. Identify the effect of protein mega structures on the texture of food: e.g. gluten in dough, actin and myosin in muscle, gelatine gel, casein curd, soya protein in tofu. Discuss the role of R groups in the binding properties of protein, with examples.

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Enzymes

Define a catalyst Describe the role and nature of an enzyme Give 3 examples of the contribution of enzyme activity to food. Explain how enzymes catalyse by lowering activation energy of reactions. Account for the specificity of enzymes using the active site and  lock and key theory Explain the effects of: temperature, pH, substrate concentration, and inhibitors on enzyme activity.

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Browning reactions

Describe the process of enzymic browning in raw fruit and vegetables. Explain the effects of: temperature, pH, substrate concentration, and inhibitors on enzymic browning of fruit and vegetables. Give examples of foods which undergo non-enzymic (Maillard) browning. Summarise the conditions required for Maillard browning to occur. Outline the major reactants and  products in non-enzymic (Maillard) browning. Describe the initial reaction of reducing sugar and amino group Discuss the pros and cons of non-enzymic browning. Compare enzymic and non-enzymic browning with respect to food, reaction type, conditions, desirability.

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Food colloids

Define a colloid
List the major types of colloid in food and describe an example of each.
Describe the formation of an emulsion
Explain the function of an emulsifier, and give examples
Sketch an emulsifier molecule
Discuss the factors affecting emulsion stability
Explain, with two named food molecules, the molecular properties needed for gelling.
Draw a diagram of gel structure including junction zones.
Explain the role of surface active molecules in foams.
Discuss the factors that destabilise foams.

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Food Additives and Preservatives

Explain the difference between a food additive and an ingredient 

Describe 2 roles of emulsifier additives in addition to that of emulsion formation

Explain the function of an emulsifier, and give examples

Sketch an emulsifier molecule

Discuss the factors affecting emulsion stability

Describe the nature and properties of thickener/stabiliser molecules

List 3 roles of thickener/stabilisers in food and describe examples in food products.

Discuss the health benefits of thickener/stabilisers.

Compare and contrast thickener/stabilisers with emulsifiers.

Define the role of a preservative

Describe the chemical reactions of nitrate and nitrite in cured meat.

Discuss the risk: benefit ratio of nitrate and nitrite as preservatives Define an antioxidant.

Give examples of antioxidant uses in food products

Name two antioxidant additives

Discuss the role of antioxidant additives in delaying oxidative rancidity of fats

Explain the role of antioxidant additives in preventing enzymic browning Name vitamins listed as additives

Describe the roles played by ascorbic acid as a food additive

Outline the conditions under which ascorbic acid is unstable

Suggest food products that could be supplemented with B vitamins

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