Choc Guide

8/11/2019 Choc Guide

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photo location

A Guide for

Teachers

Moulding

and

PackagingChocolates


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A PAC-ITsupport resource: Moulding and packaging chocolate A guide for teachers 1

Moulding and packaging chocolates

A guide for teachers

Introduction

Read this first!

Moulding and packaging chocolate is a popular technology activity in years410 classes. This resource aims to support teachers at these levels.

Moulding and packaging chocolate is authentic in that hand-made choco-lates are still produced today by skilled chocolatiers, and demonstrates theskills and knowledge required to produce a high-quality product. Unless theteacher is a trained chocolatier (in which case these notes are irrelevant!)the chocolates produced in a classroom are acceptable but can not be calledhigh-quality hand-made chocolates as the facilities will be inadequate andthere is insufficient time to acquire the required levels of skill, experienceand knowledge. This is an important teaching point, as pupils need to

appreciate the depth of knowledge, skills and experience required to pro-duce a high-quality technological product. This applies to most technologyeducation activities, as the goal is to generally educate and give pupilstechnological literacy, not to produce specifically skilled technologists. Thistopic and its activities allow important concepts to be introduced or reinforced.

Although these notes are primarily intended to support further use of thePAC-IT Teacher Guide, they introduce the whole process of mouldingchocolate. Basic information about chocolate and moulding it has beenincluded because a product is needed for packaging and because it illus-trates elements of technological practice. No learning outcomes have beensuggested as it is the professional task of teachers to define those best suitedto their class over a range of learning areas. Learning outcomes for technol-

ogy education are generally defined in these domains: conceptual,procedural, societal and technical.

While not introduced until Sections 6 and 7 of these notes,packagingis oneof the core topics for this activity as, unless immediately consumed, themoulded chocolates must be packaged for food safety and to maintain theflavour and appearance. Packaging also offers opportunities for considerableextension work. As one key function of packaging is to maintain the bestqualities of a product, these notes may assist in obtaining the best productachievable in a typical classroom situation.

Using the PAC-IT Teacher Guide

It would be helpful to first read these sections of the PAC-IT Teacher Guide(which can be ordered from this website):

Introduction to packaging, pages. 24

Packaging and society, pages 1113

Packaging functions, pages 1424

Nets of paperboard containers, pages 5661

Labelling, pages 115118 (also see the Australia New Zealand FoodAuthority website: www.anzfa.govt.nz)

If you want your pupils to develop their own packaging, this section wouldalso be useful: Developing packaging for a product, pages 2840

This column allows space

for your own notes.


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2 A PAC-ITsupport resource: Moulding and packaging chocolate A guide for teachers

Core concepts

Packaging must meet requirements for labelling.

Packaging must be attractive to the consumer.

Pathways and concepts in moulding and packaging chocolates

1 Making ownmoulds

2 Ready-madechocolate moulds

Processstarting points

Meltingchocolate

ProductsProcess stages

3 Ready-madechocolates

Finding and preparinga suitable former,

or making own former

vacuum-forminga mould

plastic mould/s

setting up a simplechocolate melter,maintaining chocolatein desired condition

best qualitychocolate formoulding

mouldingchocolates

mouldedchocolates

packagedchocolates

selecting packaging materials,designing and making packaging

packages

Core concepts

Packaging contains and protects the productfrom mechanical and chemical damage.

Packaging preserves the product, retaining suchqualities as flavours, appearance and texture.

Core concepts Foods require careful handling to ensure safety.

Standard food safety protocol (such as HACCP)are important tools in maintaining food safety.

Core concepts

A material has specific properties;some properties may be modifiedby various treatments.

Achieving required propertiesrequires appropriate techniques.

Core concepts

A technologist must be able to identifyproblems and match solutions.

Knowledge and experience are bothrequired to produce the best product.

Core concept

Conditions must be carefullycontrolled to achieve consistency.

Core concepts

Making a vacuum-formed mouldrequires a former.

Formers for vacuum-forming mustmeet certain specifications.

Topicstarting points

1 Technology:Strand C

Place of confections in our food traditions, leading toa need/opportunity to produce chocolate confections

3 Technology:Strand B

An opportunity to make moulds forhand-made chocolates

2 Technology:Strand C

Use of packaged chocolates as personal gifts;chocolate as an energy food


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Production and Process technology:

Work flow efficiency:arranging the equipment, etc., for the most efficientand safe work flow; use of flow charts in designing work flow

Quality control consistency:controlling conditions to ensure consistencyof moulding of both the plastic sheet and of the chocolate so thatunacceptable under- or oversize chocolates are not produced

Economy:reducing wastage of materials used (plastics, chocolate,

packaging), including investigating whether two or more formers canbe used with one sheet of plastic (yes, provided there is about 10 mmbetween formers)

Food safety:identifying the steps which are likely to affect food safetyand to identify and apply suitable procedures.

Structures and mechanisms:

Vacuum former design:how it is made for strength (to resist the crushingforce of the atmosphere); for even air flow (holes, gauze); necessity fora clamping frame (plastic needs to be held firmly by its edges so theatmospheric pressure can push it around the former); use of butterflynuts to enable it to be finger tightened only; etc.

Simple chocolate melter design:insulation beneath the containers toreduce heat loss to the bench by conduction (could consider adding afoam wrap to reduce heat loss by conduction to the air); lid to reduceheat loss through evaporation of water (phase change from liquid to

vapour requires heat energy); lid reduces risk of chocolate being spoiltby water drops or by water vapour; modifying a long-handled teaspooninto a ladle; etc.

How things work:an extension could be to consider how the heat-gunand vacuum cleaner work.

Economy of containers for chocolate:nets; gaining largest number of netsfrom a sheet of paperboard or heavy paper.

Graphics and drawing:

Concept drawings:sketches, rendered drawings of packaging designs (byhand, or with CAD or computer graphics programs)

Construction drawings:accurate drawings of packaging nets

Final graphics production:preparing the graphics and labelling for thepackaging and printing it on the packages.

Science

Living world:why some plants grow only in certain places; how plants

grow and manufacture materials; the nature of biological materials(carbohydrates, fats, proteins) the biology of the cacao plant and therelationship between flowers and fruits; the process of fermentation;the nature of decomposition by bacteria and fungi; finding out/measuring the energy content of the chocolate.

Material world:investigating the permeability of selected packagingmaterials (aluminium foil, various papers, polyethylene food wrap,etc.); physical effects of heating and cooling of substances (e.g. soften-ing to become plastic and hardening, melting and solidification,dissolving and crystallisation, evaporation and condensation); investi-gating the effects of adding water to chocolate; determining the effectson chocolate of various storage conditions; investigating ways of

separating some constituents of chocolate (e.g. centrifuging, chroma-tography).

Physical world:the nature of heat; how heat is transferred; differencebetween mass and weight; weighing devices to measure mass of choco-


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late; measuring the thickness of the plastic at different places of themould; measuring the hardness of different types of chocolate; detect-ing metal particles in commercial chocolate production (metalparticles from processing machinery is a constant but low-level risk infood-processing).

Mathematics

Processes:recognising the role of mathematics in this topic (e.g. needto relate the number of chocolates to be produced to the amount ofchocolate to be purchased and keeping it within budget, monitoringconsistency of production (e.g. mass) if many of one shape were to beproduced, matching chocolate sizes to its packaging, design of primarypackaging, calculating shape of secondary packaging, etc.); recordinginformation; presenting mathematical ideas (e.g. graphs of preferencesurveys).

Number:counting total production of chocolates; chocolate shapes;fraction of total of each shape; preference of people for each shape;calculating average weight of each chocolate and the average cost of

the chocolate used in each moulded chocolate; weighing chocolates ofthe same shape to find the range of masses, average mass, % variationfrom average; using density to calculate mass of a secondary package of(e.g. 100) packaged chocolates; calculating % magnification of the netsincluded if they were to be re-sized on a copier to match the sizes ofthe chocolates being made; estimating/calculating amounts of choco-late required if production extended to whole school; identifying andquantifying all costs: chocolate, capital costs of equipment, energy,time taken (with various hourly rates) link to rate and efficiency ofproduction; calculation of various returns on investment if were to sellchocolates; survey of preferences of chocolates and expressing aspercentages.

Measurement:measuring chocolates to find net size; logging the timetaken for each stage (making former, making mould, moulding,cooling, etc.); weighing each chocolate shape (e.g. for pricing); meas-ure packages to calculate volumes; make and weigh a cube ofchocolates to find the density and use density calculation to find the

volumes of the moulded chocolate shapes; devise systems of recordingthe chocolate used for each moulded shape; measure (and calculate)the area of a net in relation to the area of the sheet it is cut from (and% wastage).

Geometry:designing and making 2D nets for 3D packages; arrange netson paperboard sheet for maximum economy (maximum number fromthe sheet with least wastage) extension: investigate arrangements of

nets for efficient printing; methods of enlarging/reducing the net sizesfor different chocolate shapes; designing space-efficient secondarypackages for a number (e.g. 50) of the individual chocolate packages extension: design the secondary package to also become a displaypackage.

Algebra:drawing a graph showing the time for each stage of the mould-ing process; devise a graph which shows the relative costs of each shapeof chocolate and their packaging.

Statistics:weigh chocolates of the same shape, arrange into massgroups, make stem and leaf table of the number in each mass group,decide with the highest and lowest group are outside an acceptablerange, calculate probability of a chocolate being unacceptable (relate

to quality control of moulding process); analyse results of a preferencesurvey and express in various forms.


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English

Oral language:oral presentations sharing information gained aboutchocolate; sharing experiences with packaging designs; presentingideas on promoting chocolates in their packages, perhaps as a radioadvertisement; debating the merits or otherwise of chocolate as a food.

Written language:preparing the text for the package, including layoutand formatting; write a poem on chocolate; writing a summary of the

production of chocolate; examining how various ethnic groups mayinterpret the written description; product labelling requirements;writing an instruction manual on making formers and/or operatingthe simple vacuum former and/or setting up the chocolate melterand/or using the moulds, etc.; writing the test for print advertisementsfor various groups of consumers of their chocolates; writing a jingle fora chocolate advertisement.

Visual language:collecting advertisements for chocolates and identify-ing what each visual element, use of colour, etc., contributes to theeffectiveness of each advertisement; designing a visual advertisementfor chocolate for print or for television media; act out and video a briefadvertisement and examine the messages given by the body language,

gestures, etc.Note: Languageshave not been included here, but there is opportunity totranslate the text on the packaging to other languages and to evaluate therelevance of the graphic elements to those cultures.

Social Studies

Social organisation:investigate the situation of people who grow andharvest cacao, what they gain from it and whether they have adequatecompensation for their efforts

Culture and heritage:investigate whether chocolate has a place as asignificant food in various cultures and whether there are shapes which

must be avoided when moulding chocolates for particular cultures

The Arts

Visual arts:designing and producing the art work for packages ofchocolate; use of computer graphic programs.

Physical education and Health

Food and nutrition:the place of chocolate as a treat or variety food inthe diet could be investigated; the nutrients in chocolate; using choco-late in other recipes.


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2 About chocolate

History and production

History:By the seventh century AD the Mayas had established cacaoplantations in the Amazon and were making chocolate. The seeds(cocoa beans) made a revered beverage, xocoatl (pronouncedchocolatl, and meaning bitter water). The unsweetened drink the

Aztecs made of pounded cocoa beans and spices was probably ex-

tremely bitter. Growing chocolate:Chocolate comes from the tropical cacao bean,

Theobroma cacao(Theobroma means food of the gods). It is a delicateevergreen plant, requiring constant warmth, steady rain and screeningfrom direct light and wind. It is restricted to about 20north and southof the equator. There are three main types of varieties of cacao plants.Cacao growing countries include Brazil, Colombia, Venezuela, Ecua-dor, the nations of Central America, Ghana, Nigeria, the Ivory Coast,Cameroon, Madagascar, Sri Lanka, Java and Samoa. After 34 years thecacao begins to bear fruit. Tiny flowers grow directly out of the trunk andlarge branches. Some develop seed pods, which grow up to 25 cm long. Acacao tree fruits for about 40 years, but may yield no more than 100 kg.

Harvesting:The cacao beans are removed from their pods, fermentedin the open air to develop the flavour, dried so they can be transported

without spoilage, blended from a selection of types to give the desiredtypes of chocolate, roasted slowly at about 120 C to develop the aromaand flavour, and cracked to remove the kernels, called nibs (whichcontain 5058% cocoa butter), from the shells.

Terminology:Cacao refers to the tree, pods and unfermented beans.Cocoa refers to the manufactured products from the fermented bean.

Extraction and initial processing:The nibs are ground into a thick, darkbrown paste called chocolate liquor, which is just particles of nibssuspended in fluid cocoa butter, which receives an initial refining.

Some of the cocoa butter may be removed. If additional cocoa butter isextracted from the chocolate liquor, the solid result is ground toproduce unsweetened cocoa powder. If other ingredients are added(such as milk powder, sugar, etc.), the chocolate is refined again.

Final processing:The final step for most chocolate is conching: hugemachines with rotating blades slowly blend the heated chocolateliquor, removing residual moisture and volatile acids and breaking upthe particles. The conching continues for 1272 hours (depending onthe type and quality of chocolate), reducing particles of chocolate to2550 m in size and coating them in cocoa butter, giving a melt inthe mouth feel.

Kinds of chocolate

There are many kinds of chocolate available. Food regulations determinewhether a product can be called chocolate, generally requiring a minimumof 20% cocoa solids and no more than 5% other fats. The ingredientspanel on the packaging will allow you to judge what type it is. Chocolateshould be kept in a cool, dry place, avoiding abrupt changes of temperature.In suitable storage conditions and wrapped in foil it will keep for severalmonths. For maximum freshness purchase only when required.

There are four main types of chocolate for eating and cooking: Dark chocolatecontains sugar, cocoa liquor or mass, cocoa butter and

flavourings. Couverture chocolate is a form of dark chocolate, gener-

ally with more cocoa butter to give a good gloss and a snap whenbroken into pieces.

Milk chocolatecontains the same ingredients as dark chocolate, with atleast 20% chocolate liquor, and has milk solids added.

Caution: Some children may have

allergiesto milk solids present in

some kinds of chocolate.


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White chocolateis a mixture of sugar,full-cream milk, cocoa butter and flavour-ings.

Compound chocolatehas all the ingredi-ents of chocolate with added vegetablefats, which help it to set at room tempera-ture. It is the most economicalreadily-available form of chocolate

suitable for moulding at school and doesnot need tempering. An example isNESTLMelts, packaged in 375g

waterproof packets in dark, milk, andwhite chocolate varieties; available fromsupermarkets.

There are also chocolate-like materialsfor coating baked products. Thesecontain a softer vegetable fat so a productcan be cut without shattering the coating,but if it contains more than 5% added fatit can not be called chocolate.

Melting and tempering chocolate

Chocolate requires considerable care tohave the best final product. No water inany form (condensation, steam) must getinto the chocolate or it will cause thechocolate to bind or sieze: becomedry and grainy rather than fluid. Choco-late is best melted in a water bath, but itmust not be overheated or scorched, as it

may become hard and grainy.

cacao pods harvested, beans removed

beans fermented, dried

beans cleaned, roasted, cracked to release nibs

cocoa nibs ground, liquors blended

chocolate liquor / cocoa mass(cocoa butter + cocoa solid)

cocoa butter cocoacake

pressed

milling

conching

production

packaging

cocoa blockor bitter

chocolate

darkchocolate

milkchocolate

whitechocolate unsweetened

cocoapowder

milling

conching

production

packaging

milling

conching

production

packaging

production

packaging

grinding

packaging

+ sugar+ (optional)milk fat

+ sugar+ milkpowder

+ sugar+ milkpowder

compound chocolate (dark, milk, white)

+ vegetable fats

eating chocolate may also contain flavourings (e.g. vanilla)

Chocolate containing cocoa butter should be tempered. Temperingensures that the cocoa butter has the best crystalline form for taste andfeel, and for stability and bloom prevention. Cocoa butter has severalcrystalline forms. To grow the best form requires cooling to make thosecrystal grow, and then warming to dissolve other crystal forms. Theamount of tempering and specific temperatures are dependent on thetype of chocolate used. Note that compound chocolate does not needtempering, but care must still be taken to not overheat it and to main-tain it at a suitable temperature (around 30 C).

The cooling/warming method of temperinghas three steps:

1 Melting the chocolate by heating to (but not above) 50 C; stirwhile melting, but avoid trapping air bubbles in the chocolate.

2 Crystallising the cocoa butter by cooling the chocolate to 2626.5 C.

3 Dissolving crystals other than the desired form by warming to 3031C (dark chocolate) or 2930 C (milk, white chocolate). Place thecontainer in water at about 34 C and stir the chocolate until itreaches 3031 C. It needs to be kept at these temperatures formoulding. If it exceeds these temperatures it will need re-tempering.

Another method is to mix melted and unmelted flakes on a marbleslab to achieve the required temperature and consistency. While usedby professional chocolatiers, it is not readily suitable for classrooms.

Tempering is difficult in the simple equipment shown below as is hasno way of automatically monitoring and controlling the temperature,but if the temperature is kept around 30 C it produces a satisfactoryproduct.


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Common problems when moulding chocolate

The melted chocolate in the container becomes heavy, thick, dry, grainy.It has been affected by water and is no longer suitable for moulding.Thickening can also be caused by being left tempered too long beforeusing, when it needs to be warmed and then tempered again. Over-heating may scorch it and cause it to harden.

The moulded chocolate has streaks on the surfaceafter moulding.

This is probably fat bloom, caused by the working temperature beingtoo high, check the temperature and cool and re-temper it.

The moulded chocolate has white marks on the surface.The mould was damp, probably in the corners.

The moulded chocolate has stripes.Chocolate too cool and not properly mixed, check the temperatureand stir the chocolate.

The chocolate develops a dull grey bloomduring storage.This is either fat bloom or sugar bloom. Sugar bloom is caused bymoisture on the chocolate surface dissolving sugar in the chocolate,

which then crystallises on the surface when the chocolate dries, leavinga grey bloom. The moisture may be from being stored in a damp placeor being subjected to changes in temperature causing condensation.Dont put it the warm moulded chocolate in the freezer compartmentto cool. Erratic changes of temperature during storage may also causebloom, especially fat bloom when there is a temperature range fromnear melting to cold.

Dullwhen removed from the mould.

Probably left too long in the refrigerator. Do not leave mouldedchocolate in the refrigerator longer than necessary to cool it (it mustnot be chilled). The condensation on the cool surface when it is

removed can cause sugar bloom chocolate should be warmed in stepsto avoid condensation and the resultant dull finish and/or bloom.Cold moulds can also cause a dull finish (moulds are best warmed to2124 C before pouring the chocolate into them).

Hard to removefrom the mould.

Not cooled sufficiently; chocolate may not have been tempered beforemoulding; chocolate may have been overheated before moulding;

water may have been in the mould.


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3 Melting chocolate for moulding in a classroom

The simple chocolate melting equipment shown below will, if used care-fully, produce satisfactory chocolate for moulding chocolate shapes. Itillustrates the variables needing to be controlled in order to produce aconsistently high-quality product, and indicates the major cost factors inmaking chocolates (e.g. quality of processing from the raw materials, carefultempering and moulding, good packaging and presentation, appropriate

storage, marketing, care during transport, etc.). The best method of melting chocolate is to use a water-bath. A simple

chocolate-melter made from a 2lplastic ice-cream container is shownbelow.

long-handled teaspoonbent upwards by about 60

hole cut in the ice-cream container lidjust large enough for the body of a 500gplastic pot (with lid), Payless Plastics item126/16 make sure the rim of the potdoes not fit through the hole

2lplastic ice-cream container

insulation (e.g. Corflute, closed-cell foam)

Although chocolate can be melted in a microwave oven, the kinds ofchocolate vary in the their melting rates, and much care is required toavoid overheating or scorching it. Milk chocolate seems especially proneto scorching. The water-bath method takes longer but needs less monitor-ing and can maintain the melted chocolate in moulding condition duringa moulding session.

Note that chocolate pieces may retain their shape even when melted, soalways stir the chocolate and check the temperature before furtherheating. The appearance of the chocolate is not a sufficient guide to itsmelted state.

The steps in meltingusing the modified ice-cream container shown are:

1 Half-fill an ice-cream container with hot but not boiling water and puton the lid (which has a hole cut to take the pot of chocolate).

2 Place about two-thirds of a packet of (e.g.) NESTLMelts into thepot, partially screw on the lid, and place it into the hot water throughthe hole in the ice-cream container lid. (The pot shown is availablefrom PayLess Plastics/Plastic Box, where it is described as: Pot, 500gram + lid, stock item 126/16.)

3 Leave for about 58 minutes, then slowly stir sufficiently only to mixthe melted and unmelted chocolate. Leave for a few more minutes and

repeat the slow stirring until all the chocolate pieces have melted.4 Check the temperature of the chocolate immediately after first stirring.

It must not exceed 50 C. Ensure that by the time all of the pieces havemelted that the temperature of the chocolate is about 30 C. Add morechocolate pieces if necessary to cool the melted chocolate. Add warmor cool water to the water bath to maintain it at the required tempera-ture. Note that NESTLMelts are compound chocolates and do notneed tempering.

Having pupils read thermometers for this process provides an opportunityfor them to develop this skill and to emphasise that some processes needprecise control.

Use three chocolate melting units, one for white chocolate, one for milkchocolate and one for dark chocolate. It helps if you use different col-oured ice-cream containers for each kind of chocolate.


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4 Moulding chocolate

If the moulding of chocolate is concurrent with the plastic mould forming(assuming there are sufficient adult supervisors), the chocolate mouldingarea needs to be well separated from the plastics area. Apart from safety andsupervision issues, there is the need to ensure that the pupils have minimumexposure to the fumes, and to reduce the chance of the chocolate beingtainted.

Moulding hints

The moulds and all utensils in contact with chocolate must always becompletely dry.

A small spoonis needed to ladle chocolate into the mould. The draw-ing of the chocolate-melter above shows a long-handled teaspoon withthe spoon-end bent so it becomes more of a ladle. While miniatureladles and parfait spoons suitable for bending are available they tend tobe expensive.

Tapthe chocolate-filled mould gently on the table a few times to makethe chocolate flow fully into the mould and to bring any air bubbles to

the surface. Melted chocolate can maintain its shape, and vibrating ortapping it makes it flow; professional chocolatiers use vibrating tables.

When moulding, it is best if a refrigeratoris available in which to placethe moulds with their soft, warm chocolate. Cooling makes it easier forthe chocolate to be removed from the mould, but it is important to notleave the chocolate too long in the refrigerator. If too cold, condensa-tion on the surface when it is removed from the mould can causeblooming. As chocolate contracts as it cools it usually separates easilyfrom a clean mould (lack of separation indicates it may have beenoverheated in the melting stage).

Decorationcan also be added after the chocolates have been removedfrom the moulds.

Some of the moulds provide opportunity to use different kindsofchocolate for different parts, such as white chocolate for eyes andbuttons, milk/dark chocolate for parts of clothing, etc. Small blobs ofchocolate can be placed in the mould with toothpicks. When wantingdiscrete colours for different parts, the mould and chocolate must becooled before the next lot of chocolate is added. Marbled effects canbe obtained by pouring white and dark/milk chocolate in separatelyand streaking them together just before they set.

Using ready-made moulds

A variety of chocolate moulds can be bought from craft shops. One

disadvantage is the number of moulds on one sheet (usually 12) andyou may wish to consider cutting them into sections with two mouldsper section.

U-shaped cardboard supports could be made for the cut sections toavoid them falling over when filling and cooling. One advantage ofready-made moulds is that they are generally small.

Making your own moulds

The simple vacuum former shown on pages 90, 91 of the PAC-ITTeachers Guide is ideal for cheaply making plastic moulds for choco-late.

Why make your own moulds, and why use a simple manual home-made vacuum former? The primary goal of this topic is education, notthe high-volume production of moulds and moulded chocolates.Making plastic moulds manually is the best way of learning about the


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process of vacuum forming and the requirements of formers (e.g. noundercut parts). Using a manual vacuum former demonstrates therequirements for heating and forming (as there are sure to be failures and please use these as learning points and not treat them as fail-ures) which are required to be determined before an automaticforming machine could be built.

This simple vacuum former is cheap and the plans are sufficient for anexperienced woodworker to make one or more. The cost of a commer-

cially made machine could not be justified for this topic. A key businessconcept is the return on investment, in this instance the educationalreturn on the capital cost of setting up for this topic should be takeninto account. This vacuum former could be used for other technologyprojects, such as cases for a range of small electronic projects, slot carbodies, etc.

The photograph in the Formers for making your own moulds sectionon page 13 shows some of the formers which could be used.

The steps in making a plastic mould are:

A: Setting up

1 The moulding area should be against a wall and where there iscross-ventilation.

2 Have a bench at least two metres long pushed against a wall. Thework flow should be from one end to the other, right to left ispreferred as the majority of pupils are likely to be right-handed.

3 At the right end have a pile of plastic sheet cut to size to fit thevacuum former clamping frame (see cutting grid, left). A pair of pupilswould clamp a plastic sheet (e.g. Vivak) into a frame at this point(the vacuum former should have at least two clamping frames; whilethey are doing this the other frame is in use on the vacuum box).

4 To the left have the heating station: the heat gun on a piece of

particle board as a desk protector, leather gloves.5 At the far left is the vacuum-forming station: the vacuum box

plugged into a vacuum cleaner (with its switch easily accessible) anda selection of formers (if pupils are using ready-made formers).

Note:when making the vacuum former do not varnish or otherwisefinish the clamping frame, it must be left in its raw state.

B: Forming moulds from plastic (polymer) sheet

1 It is best if pupils work in pairs, one heating the plastic sheet and,when it is ready, the other turning on the vacuum cleaner and quicklyplacing the clamp with the warm plastic over the mould former.

2 Load the clamping frame: remove any protective layers from theplastic. Clamp a sheet of 0.5 mm PVC or PETG (preferred, e.g.Vivak) in the clamping frame and place it on a desk protected atthe minimum by a sheet of thin particle board.

3 Place a mould former on the gauze of the vacuum box.

4 One pupil has a leather glove on their left hand cradling a heat gunand holds the handle with their right hand. (Note: a hair drier hasinsufficient power for heating, a paint-stripping heat gun of 16002000 Wmust be used. Select one with the smallest amount of exposed metal on thenozzle to reduce the risk of burns.)Ensure that the heat gun is held nocloser than 100 mm to the plastic and is continuously moved in apattern which gives even heating of the sheet until it begins to sag,

nearly touching the table protector surface. Turn on the vacuumcleaner during heating. The plastic is heated more than for com-mercial moulding as there is considerable cooling as the warmplastic is transferred to the vacuum box.

Cutting pieces of Vivak to fit the

simple vacuum former shown on

p. 91 of the PAC-IT Teacher Guide

0.5mm Vivak for chocolate moulding.

(Vivak is PETG, glycol modified

polyethylene terephthalate)

Sheet size: 2455 x 1240 mm

Piece size: 155 x 153.4 mm

Number of pieces per sheet: 128

155

310

465

620

775

930

1085

1240

153

306

460

613

767

920

1073

1227

1380

1534

1687

1840

1994

2147

2301

2455

Cutting grid for a sheet of Vivak, asmeasured from the top left corner (),in mm.

The supplier may cut it to size for you, fora fee. Otherwise, mark out the cuttinglines and use a large pair of shears.


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5 The second pupil quickly transfers the warm plastic and clamp overthe former and presses the clamping frame down to ensure a goodair seal. If done correctly the warm plastic will instantly shape overthe former. This pupil would have a leather glove on their righthand to prevent injury from accidentally touching the heat gun.

6 Leave the vacuum cleaner on for about another 30 seconds whilethe plastic hardens. Do not leave the vacuum cleaner on too longor it may overheat.

7 Do not heat the plastic while it on the vacuum former!If mouldingwas not successful, re-heating the sheet while on the vacuum formeris likely to melt holes in the sheet and damage the former. Moreseriously, the plastic is likely to melt and be sucked through thegauze on the vacuum former. Having to stop the moulding sessionto carefully soften the plastic on the gauze and pull it off may be ateaching point, but it is unnecessary!

8 Remove the moulded plastic and use it for moulding chocolate. Ifthe former was clean the mould should be sufficiently sterile frombeing heated.

Safety notes

It is suggested that the area where heating is being done is against a wallso that no one can walk around the other side and risk being burned bythe heat gun (the metal nozzle of which is veryhot). The work flow shouldbe in one direction (e.g. right to left), the order being: plastic sheet andformers, the clamping frame loading area, heating area, vacuum former. (Iftwo clamps are in operation one is being refilled while another is heated.)

The person using the heat gun should wear a leather glove on their lefthand cradling the body of the gun, with their right hand on the gunhandle and switch.

The person picking up the clamp with the warm plastic should wear a gloveon their right hand (as they on the left of the person with the heat gun).

The heat gun should be placed facing towards the wall when finished; itscord should go under the desk so there is no risk of the hot nozzle touch-ing the cord and melting through to a live wire beneath.

Moulding problems

The plastic does not conform fully to the shapes of the mould.

The plastic sheet was either insufficiently heated or cooled too muchduring transfer. Heat the sheet more next time (it should sag to the baseof the clamp, i.e. about 12 mm in the centre); practise transferring theclamp; ensure that the room is warm; ensure that the ventilation is notdirecting a cold stream of air across the heating and moulding area. Donotre-heat the plastic while it is on the vacuum former. Warming (but notheating!) the former also reduces the cooling of the plastic.

The plastic moulds well at some places but not at others.

The sheet was unevenly heated. Check that is sags evenly and that heatingis extended to near the edges.

The plastic moulds well but has wrinkles in it.

The plastic was overheated. Generally the wrinkles are outside the mouldarea and so are only of cosmetic significance.

Hollows in the former do not mould well.

Drill holes into the hollows so the plastic can be sucked into them.Sharp-edged and small hollows or grooves may be too small for the plasticto bend into them and may need the edges rounded or widened. Heatingthe plastic closer to its melting point will enable sharper moulding but atthe risk of wasting the sheet if it melts rather than softens.


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Making chocolate shells for filling

Nuts are the easiest filling as they need only be pressed into themelted chocolate in a mould and then tapping the mould (we are notconsidering solid centres dipped in chocolate as it does not involvemoulding). Caution: some children may have allergiesto particularnuts.

If you wish to add soft fillings to the chocolate you need a chocolate

shell. This can be made in two ways. One method is to pour out the chocolate from the mould immedi-

ately after filling to leave a thin coating inside the mould, scrapingchocolate off the rim of the mould. The mould is put briefly intothe refrigerator and then the process is repeated until a sufficientlythick shell has built up.

The second method is to use a brush to paint chocolate over theinside of the mould, repeated as it sets to build it up to the re-quired thickness. Holding the mould with the shell up to the light

will show any places with a thin coating.

Fillings

A simple filling can be an ordinary gelatine-based jelly, but only usingabout one-third the water (note that vegetarians may not find thegelatine acceptable, but an agar-based jelly could be used instead). Achocolate with a filling such as this must be consumed within a few daysof being made (this could be used to introduce the Use by date foodsafety concept, and perhaps contrast with the Best by date where theperiod of best food quality, rather than food safety, is being indicated).

The filling is made and poured in but note that the temperaturemust be below about 20 C so that the chocolate shell does not soften.Do not overfill the shell, and tap the mould to spread the filling. Coolbriefly in the refrigerator to set the filling, then pour a thin layer of

chocolate over the filling to seal it. Ideally, fillings should have a low water content to avoid the possibility

of decomposition occurring, as sterility cant be guaranteed. A fillinghaving a low water content with a high sugar content does not readilysupport the growth of fungi or bacteria. Commercially, some softfillings are usually made by using enzymes. Liquid fillings generallycontain alcohol which acts as a preservative.

Making hollow chocolates

Hollow one-piece chocolates can be made by having a mould in twohalves (which could be two identical moulds symmetrical about the

joining plane). Fill one mould with chocolate, clamp the other mouldover it (bulldog stationery clips around the edges work well), andthen rotate the mould in all planes to evenly spread the chocolatearound the inner mould surface. Keep turning slowly until you thinkthe chocolate has set and then place in the refrigerator. If the moulddoes not come off easily, carefully flex the plastic.

Hollow two-piece chocolates can by made by joining two chocolateshells. You need a flat surface warm enough to melt chocolate (e.g. 50C); place both pieces briefly on the warm surface until the edges havemelted and then quickly push them together. The advantage of thismethod over painting the edges with melted chocolate is that the flatsurfaces also straightens the edges, giving a neat join. There is time to

quickly place small items (e.g. jelly beans, smarties, etc.) inside one ofthe pieces before joining them.


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7 Establish effective record-keeping to document the HACCP system.This would include records of hazards and their control methods,the monitoring of safety requirements and action taken to correctpotential problems.

Each of these principles must be backed by sound scientific knowledge;for example, published microbiological studies on time and tempera-ture factors for controlling food-borne pathogens.

An A4 booklet, An introduction to HACCP: Food safety informationfor New Zealand businesses is available free from your nearest re-gional Crown Public Health office. It is also available as a PDF file fromthe Ministry of Health website: www.moh.govt.nz (look under publica-tions for June 2000), or click on the link on the PAC-IT website.

There is also an accompanying document, available as a PDF: WhatDoes A Food Safety Programme Look Like?


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6 Packaging individual gift chocolates

Packaging is a core topic within this activity. Wrapping the chocolates is onlythe first step in packaging. Several nets of individual presentation packageshave been included in the next section. The range of secondary packagingof chocolates for transport and for display has not been included, but wouldbe a good extension activity.

Packaging ready-made chocolates

This option has not been described, but where only packaging is thefocus (e.g. re-packaging ready-made chocolates as a fund-raisingactivity for a school fair) the following notes are relevant.

Wrapping

The chocolates should be wrapped tightly in new aluminium foil sothey do not absorb dyes, flavours or odours from the paperboard orfrom the environment. Although new paperboard is very unlikely to behazardous to health should the chocolates not be wrapped in alu-minium foil, their taste may suffer. Chocolate is able to readily absorbodours, so an impermeable layer such as foil is important. The foil alsoretains the volatile flavours in the chocolate.

Note that recycled paperin any form is notallowed in direct contactwith food as it can not be guaranteed that the paper is free of allcontamination from previous use. Foil-wrapped chocolates could bepackaged in recycled paper or paperboard.

A simple experiment using chocolate melts to compare the perme-ability of various packaging materials is described in the PAC-IT ActivityIdeas booklet, page 11.

Decoration and labelling

The nets are best decorated before being cut out and folded. Thosewith suitable computer skills may wish to scan a net, resize it as re-quired, and to add decoration and labelling. After printing on to apage of heavy paper or light paperboard (depending on the capabili-ties of the printer) the net is cut out and assembled. Note that whileinks from computer printers are generally harmless they are notnecessarily approved for food packaging, so wrapping the chocolates infoil is essential. See PAC-IT pages 115118.

Language skills can be applied to descriptions of the package contents.A brief description of the chocolate inside (shape, size, type of choco-late, etc.) is a useful language exercise. It also raises the issue of thenecessity for accuracy of the product description. There is opportunity

here for foreign language labels. Labels could include ingredient lists, copied from the relevant choco-

late melt packages. Pupils may also like to include suggestions onstorage (e.g. To maintain the quality of this product store at roomtemperature, but not above 20C, etc.)

Labels and decoration can be prepared on separate paper to be cut outand glued to the packaging after assembly. Use an odourless adhesivesuch as starch paste. Attaching labels later provides opportunities forimaginative labelling.


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7 Nets for individual paper and paperboard packages

Package nets

The six nets for individual chocolate presentation packages on thefollowing pages may need enlarging or reducing to fit the chocolatesmade. Some designs have a glue tab, requiring an odourless adhesive(e.g. starch paste). Only two of these nets are in the PAC-IT Teachers

Guide. Make smaller containers from heavy paper (100120 gm2) and larger

containers from light paperboard (about 160250 gm2).

Common elements of the construction of this and the other chocolatecontainers shown:

copy and enlarge the net on to paperboard (if too heavy to putthrough a photocopier, copy on to paper, place the paper photo-copy face-down on the paperboard, and use a hot iron to melt thetoner on to it)

note that fold lines are shown dotted, cut lines (including slots) areshown as solid lines

decorate as required, cut out

score fold lines on the outside of the fold (i.e. fold away from thescored line, not towards it)

bend on all fold lines, using a ruler if required to ensure the foldsare straight

First:fold up &clip to theopposite tab

Second:decorate this andopposite side, fold upwards andclip to opposite tab

Note: this net has

been rotated 45to

fit it on the page


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tuckflap

glueta

bConstruction of this and the otherclip-top chocolate containers shown:

- copy and enlarge net on to thinpaperboard (if too heavy to putthrough a photocopier, copy on to

paper, place paper copy face-downon the card, and use a hot iron to meltthe toner on to the thin paperboard)

- decorate as required, cut out- score fold lines on the outside (fold

lines are shown dotted, cut lines aresolid lines)

- bend on all fold lines, using a rulerif required to ensure the folds arestraight

- locate and glue the glue tab on theinside (use an odourless adhesivesuch as starch, as it is to package afood)

- fold in the bottom flaps

- place the chocolate inside (wrappedin aluminium foil)

- clip the ears together to close thetop

It can now be presented to therecipient!

cut

fold


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these tabs fit intoslits on opposite

bottom flap


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cutfold

gluetab

gluetab

glueta

b

glueta

b

See PAC-IT pages 56, 57where nets, including

this net, are described


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foldthisinwardslast

1

2

3

4

5

fold

thisinwardsfirst

cut

fold

See PAC-IT pages 56, 57

where nets, including

this net, are described

Choc Guide

Documents

Transcript of Choc Guide