Food Engineering
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Food Engineering - Marcador
Food Engineering - Detalles
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| Triacylglcerols (TAGs) | Ester derived from glycerol and three fatty acids making of 90% of dietary fats |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Differential Scanning Calorimetry | Used to show melting profiles of fats |
| NA | NA |
| CBE | Cocoa butter equivalent. Plant-based fat, not dairy |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| SFC | Solid fat content |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Hydrogenation | Addition of hydrogen, forms desired product by eliminating double bonds in TAGs. Also, forms undesirable products forming a trans molecule which has some health issues. This process is easy to control |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| LDL | Low-density lipoprotien |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| HDL | High-density lipoprotien |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Interestification | Does not change fatty acid composition of an oil. Instead, rearranges fatty acids on glycerol to create new TAGs |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Polysaccharides (PS) | Natural polymer formed of repeating sub units. Degree of polymerisation depends on molecular weight of chain |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Water structuring polysaccharides | Hydrogen bonding between water molecules and polymer backbone allows small amounts of polymer to structure large amounts of water |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Hydrodynamic volume | Volume a polymer occupies in a solution, dontated as radius r_h |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Amino Acid | Alpha (central) carbon atom linked to an amino group or carboxy group |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Formula of amino group and carboxyl group | -NH2 and -COOH |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Gelatine | Protein derived through hydrolysis from collagen taken from animal body parts. It is brittle when dry and rubbery when moist |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| Gelatine Solution | Behave as non-Newtonian fluids. Gels upon cooling roughly 25 degree Celsius, where the temperature range depends on source and cooling rate |
| Gelatine Gels | Melt around body temperature into a Newtonian fluid, providing unique food textures mouthfeel and flavour release properties |
| Primary homogenous nucleation | Small cluster of water molecules from the basis of crystal-initiating nuclei. Rate of nucleation increases with degree of supercooling, though precautions need to be taken |
| Secondary heterogenous nucleation | Induced by presence of a surface acting as nucleus. Reduced supercooling/supersaturation on conditions are requried |
| Secondary nucleation | Starting nuclei are seeds, greater than critical ones, thus stable and thermodynamically favoured to grow. Seeds come from the breakage of bigger crystals or are added to the system intentionally. Seeds can be added to promote crystallisation |
| Diffusion Theory | Matter is deposited continuously on a crystal face at a rate proportional to the difference in concentration between point of deposition and the bulk of solution |
| Amorphous power | Obtained by rapid supercooling or rapid removal of solvent |
| Particle morphology | Shape, size, surface morphology (e.g. surface roughness) |
| Water activity | Ratio between vapour pressure of water at food surface (P) and vapour pressure of pure water at same temperature (P*). Quantity of water available for chemical and biological reactions, thus an indication of food stability |
| Freeze drying | Based on dehydration by sublimation of a frozen product |
| Freezing | Can take place using an outside freezer or directly in freeze dryer chamber by decreasing the shelf temperatures. Slow freezing = formulation of large ice crystals, though rapid freezing promotes intensive nucleation and formation of small ice crystals |
| Primary drying | After ice crystals form, rapid sublimation is accomplished by controlling the vacuum level in the freeze dryer and through careful heat input. Heat is supplied by conduction and radiation. Ice starts sublimating in the frozen product from the surfaces in contact with the heating source, leaving a porous dry cake. Water vapour is removed by mass transfer through the dried product. Primary drying only decreases moisture content to a certain value |
| Secondary drying | Carried out at warmer temperatures to remove bound water. The drying rate is slower since moisture loss only occurs by diffusion |
| Spray drying | Used for preparation of dry stable additives, instant food powders, functional ingredients and flavours. Uses a spray drying chamber and a cyclone. Can be operated co-current, counter-current or a mixture. Heat and mass transfer induced by the movement of air in the chamber. High pressure nozzles centrifugal atomizers are used. Rapid drying due to small size of liquid droplets. Residence time is 5-100 seconds |
| Cyclone | Centrifugal force causes particles to segregate from the air. Air flows out the top while particles are removed from the bottom |
| Textile or bag filter | Powdered air passes through a fabric filter before being exhausted into the atmosphere. Fine particles are trapped by the filter |
| Stages of spray drying | Initial heating, constant-rate period, falling-rate period |
| Roller/ drum drying | Liquid is applied in a thin layer and maintained as a thin film of rotating steam heated drum. Dried film is scrapped off after 3/4 complete rotations of the drum surface. Used for small volumes. Number of drums may vary, along with operating pressure, type of feed and construction material |
| Spray freeze drying | Three step process combining spray drying and freeze drying. Methods; spray freeze into vapour or into vapour over liquid or into liquid |
| Convective freeze drying | Collected frozen droplets are transferred to pre-chilled shelves for subsequent drying |
| Atmospheric freeze drying | Cold gas is used as water removal and heat transfer medium to cause sublimation at or near atmospheric pressure |
| Thermal Processing | Pasteurizing and sterilising foods to increase shelf life |
| D-value | Decimal reduction time. Heating time resulting in reducing microorganisms by a factor of 10, or one log factor |
| Z-value | The increase in temperature necessary to cause a 90% reduction in the D-value. Describes the influence of temperature on the D-value |
| Thermal death time | Minimum time to accomplish a total destruction |
| Thermal resistance of microorganisms | Place an inoculated suspension in a container and subjecting it to heat treatment . Instantaneous heating/cooling. Heat treatment is based off most resistant microorganisms that causes a health hazard or spillage |
| Retort | Heat treatment device. Uses steam to heat product to kill microorganisms |
| Commercial sterilisation | Attain a degree of sterility in product being processed so it does not undergo spoilage and become a health hazard |
| F-value | Number of minutes required to destroy a given number of organisms at a given temperature |
| Blanching | Quickly heat up food in boiling liquid and then cool down |
| Pasteurisation | Sterilising a product to make it safe to consume |
| HTST | High temperature short time method |
| LTLT | Low temperature long time method |
| Sterile product | No viable microorganisms are present. Prime concern is sterilisation processes is inactivation of spores |
| Steam retort | Steam condenses on container wall and latent heat of condensation transfers through container wall into product. This is unsteady-state |
| Amphiphilic | Both hydrophilic and hydrophobic parts |
| Emulsion | Mixture of one liquid with another which it cannot normally combine smoothly. A fine dispersion of minute droplets of one liquid in another in which it is not soluble or miscible |
| Continuous phase | Liquid |
| Dispersed phase | Small droplets |
| Bloom | If chocolate is stored at too high a temperature, surface may appear dull of white |
| HLB | Hydrophilic lipophilic balance. Predicts behaviour of emulsifiers related to their solubility. 1-20 scale. 1 = hydrophobic, 20 = hydrophilic |
| Bancroft rule | Hydrophobic emulsifiers stabilise water-in-oil emulsions. Hydrophilic emulsifiers stabilise oil-in-water emulsions |
| Foam stabilisation | Polymeric emulsifier tends to be better foam stabilisers than small molecular surfactants |
| Two building blocks of starch | Amylose (straight chain polymer) and Amylopectin (branched chain polymer) |
| Scanning electron microscope (SEM) | Can be used to observe starch granules |
| Gelatinisation | Describes the disruption of molecular orderliness within the starch granule. Water into granule-granule swells - loss of some polymer |
| Pasting | Summarises continuing starch transformation at temperatures exceeding gelatinisation temperature |
| Osmotic dehydration | Increase the shelf life of fruit and vegetables. Removal of water from lower concentration or higher concentration through a semi-permeable membrane. Greater temp. increases rate. Not on a molecular level |
| Salting | Draws water out of food, preventing bacteria growing and spoiling food. Reduces water activity. Impacts food properties. Salt plays an important role in cheese texture and stickiness of bread dough |
| Food irradiation | Uses x-rays, gamma irradiation sources and electron beams. Gamma irradiation does not increase temperature. Can be carried out on packaged food, fresh food, frozen foods and in the absence of chemical additives. Uses radiation to kill germs. Shorter the wavelength, higher the penetrating power. Dose is important. Can maintain food properties |
| What is the process for manufacturing expanded extruded snacks | Raw ingredient -> Extrusion -> Die cut -> Drying -> Oil & Flavouring -> Packaging |
| How does the extrusion process work | Raw material -> add water -> heat mixture -> hydrate, shear and cook -> pushed out at high pressure -> steam expands product -> product becomes glass -> extrudate is then cut with rotating blade |
| What outputs can change between different extruded snacks (outputs of the factorial design experiment) | Product size, bulk density, texture hardness or water content |
| What parameters can be controlled for an extruder | Screw (speed, shape and dimensions), temperature, screw fill (more full means a higher shear and higher starch damage) and water & ingredients |
| What are the three input factors in the factorial design experiment for extruded snakcs? | Barrel temperature, %water content and screw speed |
| What are the three different screw configurations | Single, twin (tangential) and twin (intermeshing). Single screw is normally cheaper |
| Define specific mechanical energy (SME) | How much energy we put into the extruder |
| How does specific mechanical energy vary with water content | Decreases linearly with time |
| What are the four types of parameters that can be changed in an extruder | Process, system, structure (reactions of different ingredients i.e. gelatinisation of starch etc) and product |
| What can be used instead of steam in the process and why is it better | Carbon dioxide, and used at lower temperature giving different textures |
| What is the main processing differences between pellet extruded snacks and direct extruded snacks | Usually lower temperatures and pressure forming a sheet to be cut and dried. Shear also tends to be lower |
| What is the process for manufacturing pellet extruded snacks | Raw ingredient -> extrusion -> shear and cut -> drying -> frying -> flavouring -> packing After drying, normally takes place at another location |
| What is the manufacturing process for potato starch | Potatoes from farm -> dry cleaning -> rotary wet cleaning -> mechanical rasping -> centrifuge sieve -> fibre sieve -> hydro cyclones -> vacuum dryer -> flash dryer -> packaging. CONDENSED PROCESS: clean -> break up -> remove cell debris -> remove water |
| What are the two main components of starch | Amylose and amylopectin |
| What is the process for gelatinisation of starch | Raw starch -> heating -> swelling -> rupturing -> gelatinisation/pasting -> imploding |
| Define pasting | Second stage swelling occurs when starch is heated above gelatinisation temperature to obtain max viscosity. More amylose is leached out and eventually gels |
| Define glass | Hard and relatively brittle |
| What are steps 1-6 for direct and pellet extrusion | DIRECT: 1) raw ingredient 2) mix with water and heat 3) glass -> rubber then gelatinisation and melting 4) exit extruder and water nucleation 5) rapid expansion and boil off water 6) dry product PELLET: 1) raw ingredient 2) extrusion heating and gelatinisation 3) drying pellet becoming glassy 4) heating and expansion 5) pellet leaves fryer and cools down 6) solid glass brittle structure |
| What are some imaging techniques for potato starch | Scanning electron microscope (SEM), x-ray tomography and stained microscopy. Smaller cell walls = harder product |
| What are some overall plant considerations | Keep well maintained, flour and improver needs to be matched, optimise recipe, mix size, set the divider/final mould/panner and regular maintenance |
| What is the Chorleywood 'Bread' Process (CBP) | Method in which the majority of wrapped, sliced industrial loaves are made in Britain |