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properties of food Flashcards

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1
Q

the effect of preservation methods on food

sensory properties

A
  • dehydration - flavour, aroma, or colour are intensified
  • addition of salt/vinegar/sugar - food becomes more salty / vinegary/ sweeter / tender / sugar has a dehydrating effect
  • canning/bottling - becomes more tender / absorb
  • s the flavour of the solution in which it is placed
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2
Q

the effect of preservation methods on food

physical properties

A
  • dehydration - becomes drier or smaller
  • addition of salt/vinegar/sugar - loss of shape or viscosity
  • canning/bottling - some loss of colour / shape / or structure
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3
Q

the effect of preservation methods on food

chemical properties

A
  • dehydration - water soluble vitamins will be removed
  • addition of salt/vinegar/sugar - salt / sugar concentration is increased: if heat is applied, vitamins may be loss
  • canning/bottling - heat destroys enzymes / vitamins/ nutrients that are added through the solution in which it is placed
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4
Q

the function of natural food components in food processing

protein – albumin

A
  • a protein found in egg white and when egg whites are beaten (mechanical action), the protein ovalbumin denatures, traps air and forms a foam (aerating mixture)
  • coagulation occurs when application of heat or acid causes protein to clot or set, changing it from a liquid to a solid due to moisture loss
  • contributes to colour, texture and functional food properties - used as a binding agent for crumbing or in batter
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5
Q

the function of natural food components in food processing

protein – gluten

A
  • gluten is the protein of many cereals, high amounts are found in wheat.
  • only formed when flour is mixed with water - createing a strong network that can be stretched like an elastic band and will spring back, trapping solid particles, liquids and gases as they expand.
  • provides structure allowing a product to hold its shape (important in the production of yeast dough and pasta which rely on a strong structural framework to enable them to hold their shape once cooked)
  • absorbs moisture which is important for binding.
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6
Q

the function of natural food components in food processing

carbohydrates – starch

A
  • the small gritty granules found in the endosperm of cereal grains
  • starch can thicken mixtures by absorbing liquid when agitated in the presence of heat, this is known as gelatinisation
  • dextrinisation of starch occurs when the starch breaks down into dextrins, causing browning.
  • starch contributes to structure, cooked starch prevents products collapsing once they have been removed from the oven and cooled.
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7
Q

the function of natural food components in food processing

carbohydrates – sugar

A
  • sugar dissolved in liquid may crystallise
  • sugar is widely used as a sweetener
  • when heated, sugar will caramelise, this causes colour and flavour changes
  • activator for yeast during fermentation helps to produce carbon dioxide which causesleavening to occur
  • tenderises by absorbing liquid in cakes. Sugar stops the flour from absorbing liquid,retarding gluten formation
  • sugar helps products to retain moisture, extending the shelf life of baked products
  • sugar raises the temperature of coagulation, this prevents curdling and causes products to set slower, giving them a smoother texture.
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8
Q

the function of natural food components in food processing

lipids – fats

A
  • the plasticity of saturated fats makes them effective at aerating mixtures as in creaming butter and sugar
  • when cream is whipped a film of protein and fat surrounds the air bubbles, the fatpartially solidifies and the protein partially denatures forming a stable solid
  • alters the sensory properties of foods. Adds moisture, tenderness, and a smooth texture to foods.
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9
Q

the function of natural food components in food processing

lipids – oils

A
  • when oil is added to a mixture and beaten rapidly emulsification will occur
  • oils are used to prevent oxidation and therefore extend shelf life
  • fats and oils are both used as cooking mediums to transfer heat.
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10
Q

functional properties and how they determine the performance of food

dextrinisation

A
  • the process that occurs when a starch is exposed to dry heat, the starch is broken down to dextrin, resulting in a change in colour to golden brown.
  • The formation of dextrin changes the colour of starch from white to brown and develops a slightly sweet, nutty flavour.
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11
Q

functional properties and how they determine the performance of food

caramelisation

A
  • he process that sugars undergo when heated to high temperatures to develop a golden-brown colour. When sugar (sucrose) begins to decompose when exposed to high temperatures (190°C) of dry heat.
  • e.g. toffee, caramel sauce
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12
Q

functional properties and how they determine the performance of food

crystallisation

A
  • heating sugar to a syrup and then cooling - sugar’s ability to dissolve and reform crystals.
  • Eg toffee making, fudge, caramel
  • If a solution is cooled quickly, small crystals will form and the product smooth. Movement and slow cooling encourages larger crystals.
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13
Q

functional properties and how they determine the performance of food

emulsification

A
  • mixing two liquids that don’t usually combine; for example, water and oil.
  • Some proteins act as emulsifying agents and hold the immiscible liquids in suspension.
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14
Q

functional properties and how they determine the performance of food

gelatinisation

A

the process that occurs when starch granules absorb liquid in the presence of heat and thicken the liquid, forming a gel.

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15
Q

functional properties and how they determine the performance of food

oxidation

A
  • chemical changes in food when exposed to oxygen
  • Eg. Oxidation occurs with the browning of meat
  • Eg. Lipids undergo oxidative rancidity if exposed to the air for a long period of time, especially in high temperatures.
  • Products that turn rancid smell and taste bad.
  • Antioxidants are substances that react readily with oxygen, delaying oxidative reactions with the food.
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16
Q

functional properties and how they determine the performance of food

denaturation

A
  • describes the permanent structural change of the protein molecules in food.
  • this can occur by application of heat, mechanical action or the addition of acids.
  • e.g. beaten egg white, poached eggs, marinaded meat.
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17
Q

functional properties and how they determine the performance of food

coagulation

A
  • a form of denaturation that occurs when there is a permanent change in the protein from a liquid into a thick mass as a result of heat or the addition of acids.
  • The denatured proteins from a new structure which retains water – a semi-liquid becomes firm and maintains its shape.
  • e.g. grilled meat, boiled egg
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18
Q

functional properties and how they determine the performance of food

leavening

A
  • the incorporation of air into products using mechanical or chemical methods.
  • Chemical- chemical raising agents used in baked goods all include an acid, the alkali bicarbonate of soda and a filler such a cornflour.
    • Bicarbonate of soda when combined with moisture and heated, produces sodium carbonate, steam and carbon dioxide.. The carbon dioxide gas is released and leavens the mixture by causing it to froth and expand up and out. The remaining residue is soda that give a bitter taste.
    • Baking powder is a commercially produced raising agent which can be added to plain flour to increase the volume of baked products. Some of the acids used in
    • Acidic ingredients used to help products rise – unsweetened cocoa, sour cream, yoghurt, buttermilk, fruit juice, vinegar, golden syrup, brown sugar. The acid ingredients dissolve when they are moistened, then react with the bicarb soda to produce carbon dioxide gas, which in turn leavens the mixture.
19
Q

functional properties and how they determine the performance of food

aeration

A
  • he process of incorporating air into food products to increase the volume and create a light, airy texture.
    • Food can be aerated by:
      • biological ingredients – yeast
        • Yeast converts carbohydrates, starch and sugar in the yeast dough to a gas, carbon dioxide, plus alcohol and water. This process is known as fermentation. Yeast needs food, moisture and warmth to ferment and leaven (rise).
      • chemical ingredients – baking powder, bicarbonate of soda
      • mechanical actions -sifting, creaming, whisking, beating, folding in ingredients, rubbing in ingredients
      • Sifting – passing dry ingredients through a fine sieve to incorporate air
      • Creaming – beating butter and sugar together traps pockets of air between the sugar crystals.
      • Whisking – the process of using a whisk vigorously to incorporate air into a mixture.
      • Beating – stirring rapidly in a circular motion with a tool such as a wooden spoon or electric
20
Q

functional properties and how they determine the performance of food

rancidity

A

the spoilage of fats and oils as a result of exposure to oxygen.

21
Q

aeration vs leavening

A
  • aeration is caused by the incorporation of air into a mixture
  • leavening is caused by the production of carbon dioxide during the fermentation of yeast
  • leavening is caused by the combination of an acid and an alkali added to a mixture and heated in the presence of water to produce carbon dioxide when
    exposed to heat the air or carbon dioxide expand and cause leavening or aeration or raising.
22
Q

factors that impact on the properties of food

processing techniques

A
  • the methods used to transform raw ingredients into finished products.
  • techniques like cooking, freezing, drying, and pasteurisation alter the texture, flavour, and nutritional content of food.
  • these techniques are essential for preserving food, enhancing safety, and creating diverse food products that meet consumer needs.
23
Q

factors that impact on the properties of food

equipment and storage

A
  • the tools and conditions used in food preparation and preservation.
  • equipment like ovens, blenders, and refrigeration units control temperature, humidity, and other factors that affect food quality.
  • proper equipment and storage ensure food remains safe, retains its intended texture and flavour, and has an extended shelf life.
24
Q

factors that impact on the properties of food

environment

A
  • external factors, such as climate, humidity, and exposure to light or air.
  • environmental conditions can influence the growth, ripening, and spoilage of food, as well as its taste and texture.
  • managing environmental conditions is crucial to maintaining the quality and safety of food, especially during storage and transport.
25
Q

factors that impact on the properties of food

ingredients

A
  • the raw materials used in food production.
  • the quality, freshness, and combination of ingredients determine the flavour, texture, and nutritional value of the final product.
  • selecting the right ingredients is key to achieving desired food properties, meeting consumer preferences, and ensuring a nutritious product.
26
Q

factors that impact on the properties of food

additives - thickeners

A

thickeners:increase the viscosity of a food, e.g. a sauce might contain a thickener to give it the desired consistency.

27
Q

factors that impact on the properties of food

additives - anti-caking agents

A

anti-caking-agents: reduce the tendency of individual food particles to adhere and improve flow characteristics. For example, seasoning with an added anti-caking agent flows freely and doesn’t clump together

28
Q

factors that impact on the properties of food

additives - humectants

A

humectants: reduce moisture loss in foods, e.g. glycerine may be added to icing to prevent it from drying out.

29
Q

factors that impact on the properties of food

additives - colourings

A

colourings: add or restore colour to foods, e.g. icing mixture is coloured to make it more attractive on cakes.

30
Q

factors that impact on the properties of food

additives - flavourings

A

flavourings: enhance the existing taste and/or odour of a food.

31
Q

factors that impact on the properties of food

additives - preservatives

A

preservatives: retard or prevent the deterioration of food by micro-organisms, and thus prevent spoilage of foods.

32
Q

factors that impact on the properties of food

additives - artificial sweeteners

A

artificial sweeteners: replace the sweetness normal provided by sugars in foods without contributing significantly to their available energy.

33
Q

technologies used to develop new food products

ultrafiltration

A
  • a technique that uses a physical barrier, a porous membrane or filter, to seperate particles in a fluid
  • for clarification, concentration, fractionation (separation of components), desalting and purification of a variety of beverages
  • applied to improve the food safety of products while avoiding heat treatment
  • examples:
    • cheese:
      • during cheese making processes some of the nutrients found in milk are lost (carbohydrates, soluble vitamins and minerals)
      • ultrafiltration is an effective means of recovering the by-products → higher nutritional value at a better price
      • ultrafiltration also removes undesirable micro-organisms from milk
    • milk (micro-filtered):
      • micro-filtration constitutes an alternative to heat treatment to reduce the presence of bacteria and improve the microbiological safety of dairy products whilst preserving taste
      • longer-shelf life than traditionally pasteurised fresh milk
      • the fluid milk is pumped over membranes which have minute pores that hold back large molecules such as protein or allow smaller molecules such as water and
        lactose to pass through
      • the natural components of milk can be separated without chemical change
      • can enhance the nutrient content of milk such as reduced fat or increased calcium or increased protein
    • benefits:
      • efficient way to gain superior quality and safety, without destroying the fundamental sensory qualities
      • removes unwanted ingredients like micro-organisms, dregs, or sediments that have a texture and increasing its shelf life that have a negative impact on product quality → makes final product more attractive in texture and longer-shelf life
      • reduce some production steps and increase yield → improves control over the production process and has low energy costs
34
Q

micro-encapsulation

A
  • the process of micro-encapsulation involves an active ingredient, surrounded by a thin biodegradable shield to form a minute capsule. Once consumed the capsule releases its contents.
  • food examples:
    • will mask the flavour of fatty acids, such as Omega-3 for people who do not eat
      fish, it is a method of including Omega-3 in the diet
    • adding Omega-3 to bread, orange juice or yoghurt used in the production of
      probiotics
    • milk or fruit juice fortified with iron
    • confectionery in which colours or flavours are encapsulated
    • chewing gum with encapsulated flavour molecules to ensure a long-lasting taste
    • antioxidants added to meat processing to increase shelf life
    • enzymes used in dough conditioners for increased stability.
  • benefis:
    • mask the flavour of the core ingredients
    • enables the release of the core material in a controlled manner (chewing gum)
    • enhance the sensory properties of a food product (e.g. colour components)
    • raising agents can be released at the right time in manufacturing
    • reduces volatility of food substances by providing greater stability from adverse
      conditions, such as oxygen, light, pH levels
    • protects probiotic bacteria from degradation in the digestive system and stays
      viable through to the colon to benefit health as intended
    • disease prevention and health promotion benefits by encapsulating additional or
      essential nutrients in commonly consumed foods.
35
Q

nanotechnology

A
  • when nanoparticles, nanotechnology techniques or tools are used during food processing system → used to manipulate materials that are generally less than 100 nano-metres (one billionth of a metre)
  • examples:
    • processed nanostructure or textured food → less use of fat and emulsifiers, better taste
    • food packaging applications → plastic polymers containing or coated with nano materials for improved mechanical or functional properties
    • nano-coatings on food contact surfaces for barrier or antimicrobial properties
    • nano-sensors for food labelling
36
Q

high pressure processing

A
  • a method of preserving food that involves subjecting food to intense pressures to kill microbes, such as yeasts, moulds and bacteria while maintaining the fresh qualities of the food
  • products with a flexible container such as a plastic bottle or pouch is placed in a pressure chamber that is then filled with water to surround the products
  • why:
    • retains flavour – flavour molecules are not affected so retains its ‘just picked’ taste, with cold pasteurisation colour is not affected, with cold pasteurisation heat sensitive nutrients are not destroyed
    • extended shelf life, shelf stable for longer, deactivates microbes
    • no distortion to the shape of the food, therefore retains sensory properties of
      appearance, no additives required to preserve the product, ‘clean’ labelling, which is of benefit to consumers
37
Q

membrane technology

A
  • nvolves using a porous membrane or filter to seperate the particles in a fluid → determined by the size of the pores in the membrane that acts as a barrier to particles that are larger than the pores while, the rest of the liquid can pass through freely
  • ultrafiltration
  • reverse osmosis:
    • filter skim milk, producing a milk concentrate that has an increased calcium and protein content (pores smaller than ultra filtration, only allowing water to pass through)
  • benefits:
    • used to enhance the nutrient content of milk
    • used a lower temperatures and suitable for heat-sensible foods
    • energy efficient
    • economical
    • used to produce protein powders and milk concentrates for export
38
Q

packaging – modified atmosphere - vacuum

A
  • where air from the interior of a package is removed entirety immediately prior to sealing the package
  • involves placing food products in a plastic film package (flexible to form around the food product), then removing with a vacuum pump, thus creating a vacuum seal
  • remove air which can spoil food product, improve shelf-life of food
39
Q

packaging – modified atmosphere - gas

A
  • used to extend the shelf life of food, using a gas flush
  • before a packaged is sealed of, inert gases (such as carbon, dioxide or nitrogen) is injected into the pack since they are heavier than oxygen, only these inert gases are trapped inside and oxygen is removed
  • gas mixtures are tailored
  • extend product shelf life, increased product integrity, protection against discolouration
40
Q

packaging - modified atmosphere - barreir

A
  • coatings that are placed onto various substances to help preserve and protect the items that are inside (harmful elements such as oxygen, water, water vapour, aromas, light, grease, oils)
  • include: barrier bags, barrier films barrier labels
  • excellent job of maintaining the positives of food, including taste, aroma, and more
41
Q

packaging - aseptic

A
  • a process whereby the food product and the package are sterilised separately and brought together in a sterile environment
  • filling and machinery must also be sterile before and during the packaging process
  • long shelf life, no preservatives are needed, no refrigeration required until opened
42
Q

packaging - active

A
  • active packaging is able to modify the environment inside the packaging as changes occur to the food
  • plastic film incorporating a chemical agent that allows for the movement of gases and water in and out of the package
  • pouches containing reactive materials or chemical scavengers are used to absorb gases that form as the product ages
43
Q

packaging - intelligent

A
  • packaging that contains an external or internal indicator to provide information about aspects of the history of the package and/or the quality of the food (sense external environment)
  • high costs associated with these packaging technology they are not widely used
  • example:
    • a sticker that changes colour if the product is kept above or below critical temperatures → indicates unsafe for consumption

food atar (6 decks)

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