sugar boiling and sugar cristalization

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Sugar boiling and sugar crystallization B.K.K.K. Jinadasa

(GS/M.Sc./FOOD/3608/08)

[05th Dec. 2009]

2009/10

Sugar boiling and sugar crystallization

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Introduction Sugar confectionery refers to a large range of food items, commonly known as sweets. Boiled sweets, toffees, marshmallows, and fondant are all examples.

Sweets are a non-essential commodity, but are consumed by people from most income groups. The variety of products is enormous, ranging from cheap, individually-wrapped sweets, to those presented in boxes with sophisticated packaging. In manufacturing candies and sweets sugar plays a major role. For this the behavior of sugars when heating and cooling is an important factor. Sugar crystallization depends on the degree of super saturation of sugar and formation of sugar crystal lattice.

When sugar containing mixtures are heated, it undergoes physical change due to evaporation of water phase. Boiled sweet types are produced by boiling sucrose; water flavoring etc. boiling is done at about 150c in an open pan and concentrated to 97-98% soluble solids. The boiling is done to remove most of the water from the syrup.

Pulling of candy gives a gloss and a white appearance to the confection. This is due to repeated drawing and folding of the plastic candy to incorporate air bubbles.


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2.1. Relation between boiling temperature and the characteristics of crystalline product

2.1.1. Materials

Saucepans

Heating system

Thermometers

Spoons

Porcelain plates

Sucrose-white

2.1.2. Method

300 g of sucrose was dissolved in 280 mL of water and heated gently with stirring in a saucepan. Solution was brought to boiling while noting the temperature at equal intervals. Portions of the solution were removed at the under mentioned temperatures and transferred on to the plates carefully using spoons. When removing and transferring the sample heat was discontinued since the heating may avoid sampling at the required temperature.

Temperatures: 111 ºC, 113 ºC, 118 ºC, 122 ºC, 132 ºC, 145 ºC, 170 ºC.

After the transferred samples were cooled they were examined for consistency, mouldability, thread forming ability, firmness/ brittleness of cool sample, taste of samples and their solubility on the tongue.

2.1.3. Results

At 111 ºC

Consistency -thin, very transparent liquid

Mouldability -cannot mould, still a liquid

Thread formation -No

Brittleness -No

Taste -sweet

Color -off white


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At 113 ºC

Consistency -thicker less transparent liquid

Mouldability -cannot mould, still a liquid

Thread formation -no

Brittleness -no

Taste -sugary

Color -light golden color

At 118 ºC

Consistency -thicker, transparent liquid

Mouldability - (very thick liquid) cannot mould

Thread formation -thin thread can be formed

Brittleness -no

Taste -sugary

Color -golden color

At122 ºC

Consistency -crystallization could be seen

Mouldability -slightly

Thread formation -can be seen

Brittleness -slightly

Taste -sweet

Color -golden color

At 132 ºC



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Mouldability -possible

Thread formation -can be seen

Brittleness -slightly

Taste -sweet

Color -golden color

At 145 ºC



Thread formation -possible

Brittleness -slightly brittle

Taste - slightly bitter with sweet taste

Color - light brown

At 170 ºC

Consistency -very hard


Thread formation -not possible

Brittleness -brittle

Taste - bitter taste

Color -brown color

2.1.4. Discussion

According to the above results, it shows that hardness of the sugar sample increases with the temperature. Consistency is also improved with the increase of temperature. But when increasing the temperature beyond 145 ºC taste was bitter.


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Mouldability increases gradually from 113 ºC but further heating leads to cracking of the structure. Thread forming ability increases with the temperature rise up to 145 ºC due to inversion (fructose). Beyond 145 ºC thread forming ability decrease due to decomposition of fructose. Color was changed from golden color to black color due to caramalization of sugar.

The temperature of boiling is very important, as it directly affects the final sugar concentration and moisture content of the sweet. For a fixed concentration of sugar, a mixture will boil at the same temperature at the same altitude above sea-level, and therefore each type of sweet has a different heating temperature. Variations in boiling temperature can make a difference between a sticky, cloudy sweet or a dry, clear sweet. An accurate way of measuring the temperature is to use a sugar thermometer. Other tests can be used to assess the temperature (for example, toffee temperatures can be estimated by removing a sample, cooling it in water, and examining it when cold). The temperatures are known by distinctive names such as 'soft ball', 'hard ball' etc., all of which refer to the consistency of the cold toffee.

Type of sweet Temperature range for boiling (0C)

Fondants 116-121

Fudge 116

Caramels and regular toffee 118-132

Hard toffee 146-154

Hard boiled sweets 149-166


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2.2. Effect of sugar mixtures.

2.2.1. Materials

Saucepans

Heating system

Thermometers

Spoons

Porcelain plates

Sucrose –white

Glucose syrup

2.2.2. Method

Above experiment were repeated using 100 g of sucrose and 183 g of commercial glucose syrup dissolved with 80 mL of water. Samples were removed at following temperatures and examined for above characters.

Temperatures: 111 ºC, 118 ºC, 132 ºC, 170 ºC.

2.2.3. Results

At 111 ºC

Consistency -liquid transparent

Mouldability -no

Thread formation -no

Brittleness -cannot be seen (soft)

Taste - sweet


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At 118 ºC

Consistency -yellow in color, slightly thick


Thread formation -possible

Brittleness -semi hard

Taste - sweet

At 132 ºC

Consistency -yellow in color, thick liquid


Thread formation -best at this temperature

Brittleness -brittle (slightly)

Taste - slightly bitter taste

170 ºC

Consistency -dark brown in color, clump can be seen

Mouldability -not possible

Thread formation -not possible

Brittleness -brittle

Taste -bitter taste

2.2.4. Discussion

With sucrose and glucose syrup in solution a higher concentration of the mixed sugars can be obtained. At 118 ºC heated sugar and glucose syrup had a good consistency, yellow brown color, good mouldability and good thread forming ability with sweet taste. The addition of certain ingredients can affect the temperature of boiling. For example, if liquid milk is used in the production of toffees, the moisture content of the mixture immediately increases, and will therefore require a longer boiling time in order to reach the desired moisture content.


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Added ingredients also have an effect on the shelf-life of the sweet. Toffees, caramels, and fudges, which contain milk-solids and fat, have a higher viscosity, which controls crystallization. On the other hand, the use of fats may make the sweet prone to rancidity, and consequently the shelf-life will be shortened.

2.3. Pulled candy

2.3.1. Materials

Sauce pan

Heating system

Thermometer

Spoon

Porcelain plates

Sugar (sucrose)

Butter

Water

Glucose syrup

Tarterate

2.3.2. Method

100 g sugar was dissolved in 60 mL of water in two sets. One set was heated up to 120 ºC and other to 128 ºC. Heated samples were poured onto buttered plates and allowed them to cool. After the plates were cooled plastic mass on each plate were pulled repeatedly drawing out and folding repeatedly until it obtained a white glossy appearance. Samples were examined for taste, colour, consistency, mouldability and thread formation.

Four types of candies were prepared using following formulations.

1. 100 g of sucrose, 60 mL of water and 2.5 g of tarterate, heated to 128 ºC. 2. Above formulation without tarterate. 3. 100 g of sucrose, 70 g of glucose syrup and 60 mL of water, heated to 120 ºC. 4. Experiment no 3 repeated using 80 g of glucose syrup. All the candies which


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Prepared were allowed to cool and observed under the microscope.

2.3.3. Results

mixture consistency Mouldability Thread formation

Brittle

ness

taste

100 g sugar + 60 mL water at 120 0C

Thick liquid turn off white color when pulled

Slightly possible

Less thread forming

soft Sweet taste

100 g sugar + 60 mL water at 128 0C

Yellow color thick solid turn to pale color when pulled

possible Good thread forming ability

Less hard Caramel flavor

100 g sugar + 60 mL water + 2.5 g tarterate 1280C

Pale in color with good spreadablilty

Possible semi solid

Good thread forming ability

Less hard Caramel flavor

100 g sugar + 60 mL water + glucose syrup 70 g at 120 0C

Pale in color Possible Good Gummy less hard

Sweet

100 g sugar + 60 mL water + glucose syrup 80 g at 1200C

Brown in color, thick liquid

possible good Gummy less hard

sweet

2.3.4. Discussion

Definition for Pulled candy is a general term referring to candies that are formed by boiling a sugar syrup and then manipulating the resulting candy by hand. The "pulling" process consists of


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stretching the still-hot mixture between two hands, bringing the ends together and twisting them around each other, then repeating the process until the candy becomes too stiff to pull. In general, pulling takes 5-15 minutes and the resulting candy should become pearlescent and more opaque. Commonly pulled candies include taffy and ribbon candy.

When tarterate is added to the confections the texture becomes soft. According to the above results 4 and 5 mixtures are suitable for confection due to good appearance, pale color, good mauldabilty, thread forming ability and sweet taste. When glucose syrup is added, mauldability and thread forming ability increases and the firmness also increase due to the increase of glucose and fructose concentration. When drawn, white glossy appearance could be observed due to incorporation of air

2.4. Reference:

sugar boiling and sugar cristalization

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