sugar technology for Diploma in Food Science and Technology.

1. SUGAR TECHNOLOGY
1.0 LECTURE ONE: INTRODUCTION
1.1. SOURCES OF SUGAR IN THE WORLD
Sugar refers to the monosaccharides and disaccharide form of carbohydrates. However
commercially sugar almost always refers to sucrose. There are three Main sources of sugar
a. SUGAR CANE
b. SUGAR BEET
c. HONEY.
Other sources include
d. The corn syrup
e. The marple syrup.
1.1.1 SUGAR CANE
This is a tall perennial grass with tillers at the base and a branched stem.There three main
varieties of sugar cane:
The botanical name for sugarcane is Saccharium officinarium
This has been known for over 12000 years. Its origin is New Guinea where it landed in
the hands of Christopher Columbus.
VARIETIES OF SUGAR CANES
a. Wild/original variety which has thin stems, a lot of trash/ leaves and not
self -cleaning. It has low sugar content.
b. Noble variety which is self -cleaning and has high sugar content, thick
stem and low fibre content.
c. Hybrid variety which has intermediate properties.
1.1.2. The sugar beet
Production of sugar from the sugar beet started in the 19th
century. It
originally contained about 4-5% sucrose but this has been improved
through breeding to about 20%.

2. growing sugar cane
billets
Comparisons between sugar cane and sugar beet.

3. 1. Sugarcane is grown in tropics where temperatures are high while sugar
beet is grown in low temperature regions.
2. Sugar cane requires more water than the sugar beet.
3. Cane is more labor intensive than sugar beet.
4. Sugar beet with only some few selective breeding has produced a variety
with high sugar content compared with sugar cane.
5. The sucrose content of sugarcane can change if it is left in the field for more
than two days. This is not the case with sugar beet.
6. The equipment used in processing of sugar from sugarcane is heavy and
expensive
1.2. Manufacture of sugar from sugar beet
Sugar beet is a root crop that grows in the temperate regions. It has a sugar
content of about 20%.
The following steps are followed in production of sugar from the sugar beet.
1. Reception, grading and cleaning once the beets are received in the plant
they are cleaned to remove the physical dirt.
2. Size reduction: the beets are cut into stripes or slices known as cossets.
3. Diffusion/extraction ; the cossets are fed into a diffuser, and sprayed with
hot water at 700
C. the movement of the cossets and the water is counter
current.
Note; the temperature of the extracting water should not exceed 700
C as
higher temperatures which lead to extraction of colored pigments from the
cossets. The residue of the cossets is used as animal feed.
4. Concentration

4. 5. Evaporation
6. Crystallization
7. Centrifugation
8. Drying and
9. Packaging.
THE CANE SUGAR
The millable cane should have the following composition.
i. Water 70- 76%
ii. Solids 24- 27%
iii. Fiber 11- 16%
iv. Soluble solid 16%
During extraction water and soluble solids are extracted and this mixed juice
should have the following composition on dry weight basis.
i. Sugar 70 -93 % of which
ii. Sucrose 70- 88%
iii. Starch 0.001%
iv. Waxes 0.05-0.1%

5. PRODUCTION OF SUGAR FROM SUGAR CANE
LECTURE TWO; CANE HARVESTING, TRANSPORTATION AND PREPARATION
2.1 TERMINOLOGY USED IN SUGAR TECHNOLONGY
A. BAGASSE: this is the fibrous residue after crushing the cane in a mill to
release out the juice
B. IMBIBITION; this Is a process by which water or dilute juice is added to the
bagasse to enhance extraction of the juice at the next mill.
C. First expressed juice: it is the juice extracted by the first set of rollers in a
mill tandem.
D. Last expressed juice: it is the juice extracted by the last set of rollers in a
mill tandem.
E. Residue juice: this is the juice left in the bagasse.
F. Mixed juice: this is a mixture of primary and secondary juice.
G. Primary juice: this is the undiluted juice, usually the first expressed juice.
H. Secondary juice : this is the diluted juice from the second and consequtive
mills.
I. Clarified juice : it is the product of clarification process
J. Massecuite: it is the concentrated syrup in which the sugar has been
crystallized or which the material has been concentrated to a point where
crystallization will start to take place.
K. Molasses: this is liquor left after crystallization has taken place and the
crystals separated by centrifugal filtration.
L. Seed: it is the fine grain used to foot in the massecuite to initiate the
crystallization process.
M. Brix: it is the percentage weight of solids in a pure solution. It is expressed
in degrees brix or o
Brix.
2.2. MANUFACTURE OF RAW SUGAR
The following steps are followed in production of cane sugar.

6. 1. Harvesting and transportation
2. Weighing and sampling
3. Cane preparation
4. Milling
5. Clarification
6. Evaporation
7. Crystallization
8. Centrifugal filtration
9. Drying
10.bagging
1.Harvesting/ handling and transportation
It is a requirement that sugar factories are located near sugarcane growing areas.
This is because cane spoils very fast hence the need to be transported to the
factory within 24hrs after harvesting.

7. Cane is also a bulk raw material (7 tonnes of cane produces 1 tonne of sugar)
hence high transportation costs can be involved.
The harvesting of cane involves the following;
a. Cane burning ; which involves setting the cane field on fire just prior to
harvesting. This has some advantages which include:
i. Scaring of the insects, birds, snakes and rodents
ii. Removing the trash
iii. Concentrating the sugar
iv. It reduces the labour cost requirement.
v. Reduces cane losses during harvesting
vi. Reduces the bulk weight of the cane hence wear and tear of the road.
vii. Shortens the harvest season by about 10%
viii. Reduces wear and tear on field and factory equipment.
Disadvantages of cane burning
i. Loss of soil moisture
ii. Destruction of organic matter
iii. Soil productivity is reduced
iv. Shorter rationing
v. Higher soil erosion
vi. Severe staling after harvesting
vii. Air pollution due to smoke
viii. Negatively affects juice clarification
ix. More dextrans in the processing.
Where the cane burning is not practiced the process is known as green cane harvesting. Green
cane harvesting has the following advantages and disadvantages
Advantages
i. Soil moisture conservation
ii. Improved soil organic matter content
iii. Reduced soil erosion
iv. Improved soil productivity
v. Longer rationing
vi. Lower weed control cost since the trash is used as mulch.

8. vii. Less severe staling after cutting
viii.Cleaner air during harvesting
ix. Improved juice clarification IN PROCESSING
x. Potentially less dextrans processing
Disadvantages
i. It is slower
ii. High labour costs
iii. Extraneous matter increase in loads
iv. More trips to the factory hence high cost of road maintenance due to wear and tear.
v. Increased field loss
vi. Slower factory through put
vii. Increase fire risk due to large area covered with dry trash.
viii. Increased overall cost.
b. Cutting of the cane: this can done either manually or mechanically using combine
harvesters.
c. The cane is then piled in stacks and arranged in rows to facilitate the loader operation.
d. Loading is carried out by hydraulically operated grabs into tractors. Weighing of the
cane is done in the field and also in the factory.
After weighing the cane it is offloaded either for immediate processing of for temporary storage
in the cane yard. In the cane yard the cane undergoes some preparations e.g. trash removal.
The cleared cane is placed on to the feed tables where it is delivered for milling. The tables
consists of conveyors to move the cane forward. They also have leveling
2. CANE PREPARATION
The objective of cane preparation is a). to cut the cane in short pieces for feeding the mills b).
Rupture the cells without extracting the juice. The preparatory devices installed before the
milling tandem are classified into three categories:
i. Knives which cut the cane into pieces
ii. Shredders which shred cut the cane into long fine pieces
iii. Fibrizer system which combine both features
a. Cane kickers; prevents excess cane being fed into the leveler which might cause
jamming of the leveler set. It consist of a shaft onto which knives rotating in
reverse direction to the cane flow.

9. b. Cane knives: cane preparation by knives consists in disintergrating the hard rind ,
nodes and breaking the cane into short pieces which in effect increase the mill
capacity and efficiency of extraction. The cane knives section consist of a forged
steel hub in which several knives are mounted in different planes. The shaft
rotate at 600rpm.
c. The shredder; this is a hammer mill adapted to function of sugarcane pulverizing.
The hammers rotate on pivots and are housed on a thick still plate. As the shaft
rotates the attached shredders cut the cane into thin pieces.

12. The efficiency of the cane preparation is determined by the % of the opened cane cells.
LECTURE THREE: MILLING OF THE CANE
There are two methods of extracting the juice from the cane.
A. Pressure milling
B. Diffusion method.
3.1. Pressure milling
The prepared cane is conveyed to the milling rollers for crushing.

14. F= FEED ROLLER
T= TOP ROLLER

15. D= DISCHARGE OR DELIVERY ROLLER.
The rollers are made of heavy cast iron and they are basically drums moulded on a heavy steel
shaft. They are parallel to each other with the Top roller sitting almost equally between the two
lower rollers. Between the two lower ones there is a trash plate that prevent any cane being
crushed from rolling down and also guides the cane to the delivery for further processing. The
pressure is exerted so that the juice is squeezed out at points where rollers get into contact
with each other i.e. T-F and TD.
There is a provision for a channel of juice to escape without allowing the passage of the
bagasse.
The rollers have grooves which run through the circumference as the rollers rotate. They
facilitate the separation of the juice from the bagasse. This separation improves the efficiency
of extraction and prevent the contact between the bagasse and the juice.
3.2. EXCTACTION OF THE JUICE FROM THE BAGASSE
This starts from mill 2 to the final mill. As the extraction proceeds, the bagasse becomes dry
and juice extraction becomes difficult. It is therefore not possible to extract all the juice from
the bagasse. The bagasse retain some juice equivalent to the weight of the fibre. To achieve
maximum extraction of sugar it is necessary to dilute the juice inn the bagasse.
This procedure is known as imbibition and is carried out by addition of water. Cold or hot water
can be used for this procedure but hot imbibition is rarely used as it can cause corrosion of the
mill. Moreover it would require some energy to heat.
There are two systems of imbibition;
a. Simple imbibition; In this system water is added to bagasse after each mill.
b. Compound imbibition: water is added in the last mill and the juice from the last mill
become the imbibition water for the previous mill. The juice from the fifth mill is used as
imbibition water for the fourth mill and the juice from the 4th
mill is used asd imbibition
water for the 3rd
etc.
The process is counter current. The imbibition water is provided by perforated pipes
which release water in form of jets at high velocity. This high velocity allows water to
penetrate the bagasse.

16. The efficiency of imbibition depends on:
i. The % of juice extracted by the 1st
mill.
ii. The amount of water added
iii. The number of imbibition steps
iv. The proportion of open cells.
CANE DIFFUSION / REPLACEMENT WASHING
It is a requirement that the cane be ruptured up to 94% of the cells in order to from permit
such displacement washing. In order to obtain satisfactory washing from the stroma of the
cells, they should be broken and released from the fibre bundles. This requires thorough cane
preparation to open up the cane cells as quickly as possible. Some of the diffusion systems have
one roll before the juice is introduced into the diffusor. The diffusion of sucrose from the
diffusor acts on the principle of osmotic pressure.
3.2. The diffusion process

17. Prepared cane is passed through the diffuser with aim of extracting sucrose. Hot water is
added into the cane for displacement washing. The flow of the cane and the cane is
countercurrent.
During the process the exposed cane cells are broken open and sucrose molecules with other
substances diffuse out of the cell in to the water forming raw juice.
Sucrose is more concentrated in the cells than in the water. Hence it moves from the cells to
the water by osmotic pressure.
Hot water is used in this process because.
i. It destroys microorganisms e.g. Leuconostoc.
ii. High temperatures kill non open cells of the cane to permit diffusion through the cell
wall.
There are two diffusers used percolates through the bed to wash out the pores.
a. The cane diffuser
b. The bagasse diffuser
The diffuser is an enclosed chamber through which a bed of prepared cane is slowly dragged
while quantities of water. It is divided into several stages
Lime is added into the diffuser to lower the acidity so that the pH is about 6.5. this reduces the
corrosion and inversion of sucrose. High temperatures between 85 and 90o
C prevent bacterial
degradation of sucrose.

19. LECTURE FOUR; JUICE TREATMENT
4.0. Introduction
1. Heating;
The juice is heated using heat exchangers to a temperature of 105o
C. This is done
rapidly to minimize inversion of sucrose.
The purpose of heating.
a. To sterilize the juice
b. To speed up liming of the juice
c. To coagulate the freely suspended matter e.g proteins.
2. Clarification process.
Juice received from the mills or the diffusers commonly termed as raw-juice or the
mixed juice is turbid in appearance and contain impurities such as bagacillo and other
impurities of organic and inorganic origin either as suspension or dissolved state.
These impurities are removed by a process known as clarification.
Aims of clarification
i. Elimination of suspended impurities and colloids
ii. Removal of maximum non sugar components in the solution.
iii. Imparting clarity and transparency in the juice.
4.1. CLARIFICATION METHODS
4.1.1. DEFECATION
This is the oldest method of clarification. It employs mainly lime (liming) phosphoric
acid(phosphoration) and heat as the liming agents. For optimum results in this method, the
juice must contain 300 mg of P2O5 per litre.. incase the juice are deficient in natural phosphate,
inorganic aphosphate or phosphoric acid are added to bring the P2O5 to the required level.
The added lime performs the following functions / reactions.
a. Neutralizes the free organic acids
b. Forms insoluble tricalcium phosphate CA3(PO4)2 precipitate which occludes colloids and
suspended impurities.
Liming methods

20. a. Cold liming- The cold juice is limed to pH 7.8- 8.3 and heated to 103 to 105o
C. The
pressure is released, vapours vented out and the juice sent to the subsider for
settling.
b. Hot liming- juice is heated to 70O
C then treated with lime to raise the pH to 7.8, the
treated juice being reheated to 103O
C before being sent to subsider.
The following procedure is followed.
(a) Phosphoric acid is added to weighed juice to raise the phosphate to the desired level
(b) The juice is heated to 70- 75 O
C in the juice heater.
(c) Liming to pH 7.4 -7.6
(d) Heating to 100-102 O
C and sent to clarifier.
(e) Clear juice drawn continuously by overflow and sent to evaporator.
(f) The underflow or mud is sent for filtration in the vacuum filter.
(g) The turbid filtrates from the filter are sent to weighed juice receiving tank.
Advantages of hot liming
Coagulating the colloids at low pH
c. Fractional liming and double liming
The following procedure is followed
(a) Add lime to cold low juice to pH 6.2 – 6.4
(b) Heat the limed juice to boiling
(c) Add the remaining dose of lime to pH 7.6
(d) Heat again to boiling
(e) Send to the clarifier
Advantage; it results to better settling and clarity of the juice.
REACTIONS OF DEFECATION
Ca+2
+ HPO4
_2
CaHPO4
Ca+2
+ 2PO4
_3
Ca3PO4

21. 4.1.2. SULPHITATION PROCESS
This is purification of juice of juice by employing sulphur dioxide and lime. In the
sulphitation lime reacts with sulphurous acid as follows.
SO2+H2O H2SO3
Ca(OH)2+ H2SO3 Ca SO3+H2O
The calcium sulphite formed is insoluble and therefore occludes other suspended
matters. These impurities are removed as underflows as in the case of defecation.
Effects of sulphitation
a. Removal of suspended impurities in the juice.
b. Brings down the colour contents
c. Removes turbidity
d. Increase in purity through the removal of non-sugar components
4.1.3. CARBONATION
This implies the formation of calcium carbonate for the purification of juice. It involves the
addition of calcium hydroxide followed by addition of carbon dioxide gas in to the juice
Calcium hydroxide reacts with carbon dioxide to form calcium carbonate. It is this Calcium
carbonate that occludes the suspended particles.
Effects of carbonation
a. Removal of ash content of the juice
b. Removal of organic non sugars e.g. gums, pectin and nitrogen.
c. Reduction in reducing sugars
After clarification the coagulated impurities are separated from the juice by decantation where
the clear juice is removed as the overflow. The clarification process can be optimized by:
a. Washing the cane prior to milling and processing.
b. Treating the juice with phosphoric acid
c. Use the correct amount of lime and proper contact time (3hrs) and temperature
(1040
C).

22. After the clarification the juice undergoes the screening process to remove the fine
bagacillo. This is done in rotary drum filters.
4.2. Filtration of the mud from the clarifier
In this process the suspended matter and heavy particles coagulated by heat and lime
settle at the surface of the clarifier in form of sludge or mud.
The sludge is removed from the clarifier into the mud thickening compartment.
It is pumped by means of suction to a mud box where it undergoes filtration process.
In the mud box, heavy mud is added to thicken the sludge.
The mixture of the mud and the bagacillo is filtered in a vacuum drum filter. Wash water
is then applied to wash out the mud. The filtrated is piped to the weighed juice tank.
Uses of the mud cake
1. As a fertilizer in sugarcane plantation.
2. Used as land fill
Impurities Removed in the clarification process include:
i. Fine bagasse (bagacillo)
ii. Coloring matter
iii. Wax
iv. Organic salts
v. Acids
vi. Non sucrose soluble solids
4.3. EVAPORATION
4.3.0. Introduction: the clear juice from the clarifier contains about 83 to 85%
moisture content ( or about 15 to 17% total solids. Most of this water has to be
removed to allow the crystallization process to take place. This produces a heavy syrup
usually 65o
Brix. It is done by boiling of the water.
The evaporation of water from the juice takes place in a multiple effect evaporator. In a
multiple effect evaporator, the vapors in the first effect are used as steam in the 2nd
effect while the vapor from the 2nd
effect is used as steam in the 3rd
effect etc. the
multiple effect evaporators have the following advantages.
a. Steam economy i.e. 1kg of steam is used to evaporate 4-5kg of water.
b. Exposure of juice to high temperatures is reduced thereby reducing sucrose
destruction to minimum.

23. c. Vapour from any vessel can be robbed for heating the juice or pans thus reducing
the steam load in the process of sugar manufacture.
Problems associated with evaporation
a. Entrainment; this is where some juice containing some sucrose is trapped in the vapour.
This may lead to wastage of sucrose. To eliminate the problem entrainment arrestors
are incorporated to ensure that sucrose droplets will not escape with the vapour.
b. Scale formation; scale formation occurs due to presence of sulphates and chlorides of
calcium and magnesium in the water (due to water hardness).
Formation of scales reduces the rate of heat transfer since they act as insulators.
Scaling can be severe and can result in shut down of the equipment for cleaning to
improve the performance.
Scale removal;
Methods of scale removal are classified into two;
i. Mechanical methods
ii. Chemical methods
Mechanical methods
This refers to physical methods like scrubbing, or brushing which can be done manually or
mechanically using machines.
These includes: hand operated and powered scrubbers and cutters.
Mechanical methods
These are more popular. An alkaline e.g. caustic soda solution is circulated in the system
followed by weak organic acid which acts on the colloids especially those that are nitrogenous.
In practice a combination of mechanical and chemical methods is used.
CALCULATION OF THE EVAPORATED WATER
The total water to be evaporated can be calculated from the brixes of the juices and
syrups entering and leaving the system, the main basis being that the total solids remain
unchanged.

24. Example 1
Assume you have 100kg of juice with a concentration of 140
Brix. The cane juice is to
evaporated to 650
Brix. Calculate;
a). the amount of water evaporated
b). the syrup yield
Solution
W1=100
W2=?
B1=14
B2=65
E=?
Substituting into the equation
E=100(1-14/65)
E= 100(1-0.215)
E=78.5
W2= 100-78.5=21.5
EXAMPLE 2
A fine mill crushes 150 tonnes of cane per hour to yield 10.6 tonnes of 150
Brix of
clarified juice. In the evaporator, the juice is evaporated to obtain 700
Brix.
a. Calculate the amount of water lost per hour.

25. b. Calculate the syrup produced in one hour
Solution
B1= 15
B2=70
W1=10.6
W2=?
E=?
E=10.6(1-15/70))
E=8.33 tonnes
LECTURE FIVE; CRYSTALLIZATION/ SUGAR BOILING, CENTRIFUGATION,
DRYING AND BAGGING
5.1. CRYSTALLIZATION/ SUGAR BOILING
When the syrup is heated in a vacuum tank, water is evaporated. Under care boiling of the
solution, crystals will result. In sugar processing crystallization is carried out in a single effect
vacuum evaporator. The use of vacuum ensures saving in terms of energy since evaporation
takes place at lower temperatures.
The evaporator
Are designed to handle viscous materials.
The evaporation equipment consists of
i. Space for boiling liquid vapour.
ii. Heating element
iii. Entrainment separator to prevent loss of sugar.
The sugar syrup undergoes 3-4 stages during the crystallization.

26. CRYSTALISATION AND CENTRIFUGATION
FIRST MASSECUITE 600
BRIX
This consist of essentially the syrup from the evaporator. When concentrated crystallization
takes place to produce the sugar crystals and the molasses (mother liquor). During boiling
stage the massecuite after attaining super saturation it is discharged from the vacuum pans it is
sent to the centrifuge for separation. This separation produces A SUGAR and A MOLASSES.
Sugar A is marketed as the mill white sugar
THE A molasses forms the BASIS for B MASSECUITE (SECOND MASSECUITE) which inturn
undergoes evaporation to Superstaturation followed by separation to produce B SUGAR and B
molasses. Some factories package the B SUGAR as the brown sugar.

27. The B molasses forms the basis for C MASSECUITE .
C is the final massecuite and moves from the pans to the crystallizer. It does go straight like A or
B massecuite to a complete crystallization through the cooler. This is because the particles are
to small and can be lost during centrifugation.
The C sugar is used as A grade sugar. In practice it is mixed with syrup and water to form
magma which is used in A or B PANS as seed or footing to induce some crystallization. This use
of C sugar as footing is to produce high quality sugar is known as magma system.
The use of three stages of crystallization helps to preserve the fluidity of the massecuite, after
every stage of crystallization, the sugar crystals are separated making the liquid less viscous.
In order for crystallization to take place, the syrup solution should be supersaturated.
SUPERSATURATION is a state of saturation by expelling sucrose i.e. by forming new
crystals or by depositing itself on the existing crystals. Super saturation depends on
temperature and it is the driving force in crystallization.

28. There are three levels of super saturation
A. Lower phase/ metastable zone; the sucrose solution is slightly super
saturated and left at this condition no change will occur. Sucrose crystals are just about
to form. Addition of small sugar crystals will result in growth of these crystals as sucrose
is deposited from the solution hence reducing the state of super saturation.
B. INTERMEDIATE ZONE: new crystals form readily as existing crystals continue to
grow.
C. Labile zone: the solution at this state is very unstable and spontaneous nucleation
occurs. There is no control over crystallization.
GRAINING
This is establishment of grain footing for any boiling, containing the sugar grains of the
right size and sufficient number, employing one of the following three methods:

29. I. Waiting method; the syrup is concentrated up to the labile zone of super
saturation when fresh crystals are formed. When the operator perceives that
sufficient grain has been formed, he arrests further gain formation by giving
charge of water or by lowering the vacuum( increasing the temperature) of the
strike. This lowers the super saturation to metastable state. The syrup is
maintained at this metastable state to allow grain formation. Water drinks are
added to harden the grains therefore given them a definite size.
II. Shock seeding: the solution is concentrated up to metastable zone. Finely
ground sugar is charged into the pan, raising the super saturation to
intermediated zone. In this system the particles of sugar do not act as nuclei but
act as shock for inducing new grain formation at a lower supper saturation than
in waiting method. After sufficient grains are formed the super saturation is
lowered to metastable zone by charging with water or lowering the vacuum.
III. True seeding method: there is no grain formation but instead the development
of fine grains is initiated by addition of slurry containing sugar and non-aqueous
solvent. The weight of sugar in slurry to be fed to pan is determined by ratio of
the weight of the given number of sugar grains of unit volume of strike to that
equivalent number of grains in slurry. It is given by:
(d/a(b/c)
Where;
(a). weight of sugar per cubic meter of massecuite in Kg.
(b). weight of 500 sugar grains from the massecuite in grams
(c). weight of 500 sugar grains the slurry in grams
(d). Final volume of strike to be boiled in m3
.
Superstaturation is maintained at metastable zone. Water is charged intermittently to harden
the grain.
Methods of preparing the slurry
The medium for seed slurry is some organic solvent which has lower boiling
[point than water so that the solvent explodes on entry in the pan so that sugar
particles get distributed into the supersaturated syrup. Either of the following
solvent can be used.
i. Denatured ethyl alcohol
ii. Isopropyl alcohol

30. iii. Mixture of ethyl alcohol and glycerin
iv. Gasoline
Factors affecting massecuite formation
a. Pressure: Lowering the pressure lowers the boiling point hence saving on energy.
b. Temperature: Higher temperatures causes chemical reactions e.g. caramerisation
which is undesirable
c. Conductivity; heat exchangers should be made from good conductors, and their
outer surfaces lagged with poor conductors to prevent heat loss.
d. Stirring and agitation; stirring allows the sugar crystals to grow continually.
e. Size of crystallizers: large crystallizers make centrifugal operation to take longer
f. Size of the crystals: there is legal requirement for the size of the crystals. This
should be taken into consideration during boiling.
5.2. CENTRIFUGATION/ CRYSTAL SEPARATION
This is a unit operation in which the massecuite is separated into crystals and the molasses
through the application of centrifugal force. The centrifuges can be batch or continuous. The
batch centrifugal is used to separate A continuous centrifugal is used separation of B and C
sugars from their respective molasses
A centrifugal machine basically consists of:
a. A revolving basket with drive arrangement.
b. A monitor casing
In a batch centrifugal machine the basket is a cylindrical drum with perforations,
supported on a heavy vertical shaft with drive arrangement at the top. The basket is
open at the top and at the bottom. The bottom is kept closed during charging and
running but opened during discharging. On the other hand the top is kept open while
charging. The perforated basket is lined with wire gauze and a perforated brass liner for
allowing the separated molasses to flow out, while retaining the sugar crystals.
The basket is surrounded by a fixed casing known as the monitor casing which is open at
the top and is provided with sliding covers for closing the machine during the operation.
Water pipes are provided for washing the sugar.
A mechanical sugar discharging plough is mounted at the top of the casing.

31. PRINCIPLE OF CENTRIFUGAL FILTRATION- In a centrifugal machine revolving at
high speed, the centrifugal force exerted on the mass consisting of sugar crystals surrounded by
viscous liquor brings about separation of mother liquor from the crystals. The mother liquors
through the perforations while the crystals are retained on the wall of the basket lining.
Operation of a centrifugal system.
The entire operation of a centrifugal separation involves the following steps.
i. Taking charge: The centrifuge is opened, the massecuite fed in, closed and ran at low
speed (200-300rpm)

32. ii. Running at intermediate speed; speed increased to 700- 750 rpm before it is
accelerated to highest speed to prevent packing of the sugar in the basket.
iii. Running at full speed 1450 -1500rpm; maximum separation of molasses from sugar is
ensured. At this stage water wash is given to wash of the molasses from the sugar.
Wash water follows the same path as the molasses. The machine speed is brought
down to 50rpm ready for ploughing.
iv. Ploughing: At 50rpm, the sugar is scrapped off when the bottom cove of the centrifuge
is lifted and sugar discharged to either conveyor or mixer.
5.3. DRYING AND STORAGE OF RAW SUGAR
The A sugar leaving the centrifuge has 0.5 to 2% moisture content. This can cause
growth of bacteria or caking of the sugar crystals.
The drying process of sugar takes place in two stages
1. Removal of unbound water; it involves the removal of free water surrounding
the crystals. Its usually carried out in driers leaving a moisture content of 0.02-
0.03. it inhibits the growth of spoilage microorganisms.
2. Removal of bound water. This involves removal of water of crystallization. If not
removed this water oozes out casing caking of the sugar crystals hence the
handling of the crystals becomes difficult.
Sugar is dried by hot air in a drying cyclone. After drying , a stream of cool air is supplied to
regulate the temperature to minimize caking. The crystals are conveyed to vibrating screens to
separate them into different sizes.
Aims of controlling the moisture content.
a. Inhibit microbial growth that may lead to fermentation.
b. Reduce sucrose loss through caking
c. Reduce impurities in sugar.
SUGAR BAGGING
Raw sugar is bagged after weighing. The packaging material should ensure that sugar does not
pick up moisture from the environment. It is packaged in jute bags lined inside with polythene
bags that are moisture proof. The bags are sealed labeled and stacked in ware houses for
distribution.

33. LECTURE SIX: SUGAR REFINING
SO far we have covered the major steps involved in production of table sugar. At
this point we have two main products.
a. A sugar aka Mill white sugar
b. B commonly marketed as brown sugar.
As previously noted C sugar is normally recycled as magma used footing for
other types of sugars.
The refining process produces the third major type of sugar known as the refined sugar which is
more purer that the mill white sugar.
The main purpose of refining is to produce white sugar that is free from impurities. The general
aim is to remove the adhering molasses. The major steps involved in production of white sugar
are as follows
a. Affinition
b. Clarification
c. Decolourisation
d. Crystallization
e. Drying and finishing
AFFINATION
It is the mechanical removal of the adhering molasses from the crystals of raw sugar.
This is because the adhering molasses has low purity i.e. 60%. The raw sugar is mixed
with a heavy syrup 700
Brix. This softens the adhering molasses and removes the
molasses from the crystals. There is also application of mechanical rubbing of the sugar
crystals which produces the affinition greens i.e. the crystals and the syrup mixtures.
The mixture go through centrifugation process to separate the crystals from the syrup.
The crystals are then washed with hot water to remove the remaining traces of
molasses as much as possible. The affinition syrup is treated separately for purpose of
extracting the sugar.
MELTING
They affined crystals are the washed in hot water (this is known as melting) to produce a
syrup of about 600
brix . which is ready to undergo clarification process.

34. Flow diagram of sugar refining
f.
CLARIFICATION
Affinition process does not remove all the impurities in sugar so further
processing is necessary. There are two types of clarification
a. Chemical
b. Mechanical clarification or filtration .
CRYSTALLISATION
CENTRIFUGATION
AFFINATION
MELTING
CLARIFICATION
FILTRATION
DECOLORISATION
RAW SUGAR

35. Chemical methods where are used to form precipitate in the syrup. The common chemical
methods used include:
A. CARBONATION; in which calcium hydroxide and carbon dioxide are pumped in the
syrup. The two reacts to form calcium carbonate precipitate which removes the
impurities since it has high affinity for impurities.
B. Phospholation; which is addition of lime and small amounts of phosphoric acid.
Precipitates of calcium phosphate is form. The precipitate traps the impurities
Mechanical method filtration
This follows the chemical method to remove the clarified solids from the syrup. Vacuum drum
filter is used.
DECOLOURISATION;
The syrup is passed through decolorizing agents e.g. activated animal charcoal. The purpose
being to remove traces of colour pigments remaining in the syrup.
The animal charcoal is prepared by heating the animal bones in absence of air followed by
grinding them to suitable granular condition which is a very active form. This form can absorb
pigments especially when used in a porous calcium base. The bone charcoal system is very
effective and is regenerated by passing it in a vacuum and heating.
Crystallization is carried out followed by centrifugation, drying packaging and distribution as
earlier discussed.
Quality of raw sugar
The quality of the product is controlled by weighing and analyzing it at intermediate steps. The
by products are also analyzed at each step.
The loss of sucrose can result due to:
a. Chemical losses e.g. inversion and fermentation.
b. Mechanized process spoilage.
The yield of sugar is given by:
( )

36. Test for quality specifications
1. Sugar content; it measured by brix purity of the crystals.
2. Pol; it is the apparent sucrose content expressed by mass
percent measured by optical rotation of polarized light through
sugar solution.
The apparent purity of the solution is given by
( )
3. Invert sugar sucrose ratio: it is given by
4. Fibre content
5. Ash: it is an indication of mineral composition of the sugar. It done by use of
concentrated sulphuric acid.
Physical tests on raw sugar.
Color; Measured by transmittance or absorbance of light.
Taste: should be odourless and only sweet taste.
Crystal size: crystals should be easy to dissolve; hence the size should be controlled to
ensure solubility.
Microbiological tests. Yeast and mold tests should be carried out to ensure
microbiological quality of sugar.
LECTURE SEVEN; HONEY PROCESING
7.0. INTRODUCTION
Bee keeping in Kenya has been practiced since time immemorial. Currently there are two
million hives in the country. Most bee keepers in Kenya base their practice on indigenous
knowledge which has been passed from one generation to the next. Areas covered with bees in

37. the country include the mountainous areas, the savannah area, the coastal region and the drier
parts of northern Kenya.
Honey is a natural product produced by honeybees and consists of a very concentrated solution
of a complex mixture of sugars, in which fructose and glucose are the main ingredients. It is the
natural sweet substance produced by honey bees from the nectar of flowers.
It is also produced from blossoms or secretions of living parts of plants or excretions of plant
sucking insects, however, honeybees collect transform and combine nectar with specific
substances of their own, store and leave in the honey comb to ripen and mature. Bees produce
blossom honeys from nectar and honeydew honey from honeydew. Honeydew is the product
of small plant sucking insects.
Honey is used as a flavoring agent in honey cakes and gateaux. Its flavor which is distinctive
varies with the type of vector. The different flavors are the result of characteristic aroma of
flowers from which the nectars are gathered. It is the comb-honey that is stored by the bees in
the cells of the wax honeycomb.
Harvesting of Honey
Honey is harvested early in the morning or late in the evening when bees are less active.
Following steps are followed:
holes using a smoker. The smoke makes the bees to start eating honey thus becoming heavy
tool, gently knock upper surface of the top bars to find out where the building of the combs
ends. Lift off the last build comb and inspect for ripe honey.
put them in a clean
Aggregation and Processsing
Aggregation Aggregation is the collection, gathering and transportation of harvested honey to
the refineries for processing. Most beekeepers in Kenya are rural based while processing
plants are located in urban areas. Harvested honey is put in plastic containers (jerricans) and
loaded onto lorries and trucks for transportation to processing centres. Honey produced is
gathered by individual beekeepers and collected through self-help groups and cooperatives for

38. deliverance to the processing plants. Quality assurance is expected to be adhered to in the
factories.
Processing There are three common methods of extracting honey from the combs which
include:
Using heat to melt.
i. Heat some water in a sufuria.
ii. Put honey combs in an enamel basin or any other container which is not made of iron.
iii.
honey melts.
iv. Separate the melted honey from the combs by straining through a muslin cloth.
v. Keep honey in a container to cool down.
vi. Remove the wax layer that may form on the surface of the honey.
Crushing and Straining
This method produces the highest quality honey. The following should be done:
Honey combs are crushed and strained using a muslin cloth into the enamel
basin. The scum formed is removed with a wooden spoon. The pure honey is put
in a suitable container (plastic or glass jars) that is tightly closed.
Using a Centrifugal Extractor
A centrifugal extractor is used in large scale production. The combs are decapped and placed in
the extractor. The rotary motion forces out honey and combs are left clean. Honey removed
from the honeycomb is by centrifugal force and thus honey called extracted honey.
Benefits of honey
Honey is a functional food and has different biological properties such as antibacterial
(bacteriostatic properties), anti-inflammatory, wound and sunburn healing, antioxidant, radical
scavenging, ant diabetic and antimicrobial activities. Honey industry in the country can well
become a major foreign exchange earner if international standards are met.
Honey in the market is presented in several forms:

39. 1. Unprocessed Honey This is honey in its raw form, with combs that have been broken
to release the honey from the cells. Demand for this honey is high. The main market outlet is
traditional brewers and herbalist. Price depends on supply and demand. Currently farm gate
prices range from Ksh70-150 per kg.
2. Semi-Refined Honey
This is mainly honey where most of the combs have been manually removed leaving the liquid
honey with few impurities. Demand is very high mainly from processors and packers. Price
ranges from Ksh80-170 per kg depending on the season.
3. Refined/Liquid Honey
This is honey that has been strained to remove all the foreign particles. It is normally packed in
plastic or glass jars of 350gm, 500gm or in any other convenient pack. Retail price range
between Ksh150-300 for the 500gm jar.
4.Chunk Honey
This is honey that has a piece of comb honey immersed in refined liquid honey. Packages used
are normally glass jars. This form of honey is not very common in the market however;
consumers who like both comb and refined honey will usually pay a higher price for this special
chunk honey pack.
5.Creamed Honey
This is honey that has been made to solidify under specific conditions. The crystals are very fine
and not visible, therefore can be spread easily like butter. The marketability has not been fully
exploited due to inadequate skills for its preparation and low consumer awareness.
6. Comb Honey
This is honey contained in the cells of the comb in which it is produced. Good comb honey is to
the beekeeper and consumer a product of beauty. The comb honey should be kept intact until
it ready for market. Preparation for market involves cutting sections of the comb into various
shapes and sizes depending on the package.

40. Flow chart for refined honey processing

41. LECTURE EIGHT; NON SUCROSE SWEETENERS
INTRODUCTION
 Sugar (sucrose) being the most acceptable sweetener in use by mankind is considered
an arch criminal in dental carries
 Dental carries occurs when acid producing bacteria, especially Mutans
Streptococci,Lactobacilli, and Actomyces species, populate the sticky coating on the
surface of the tooth.
 Frequent consumption of fermentable carbohydrates, including sucrose, has a role in
aetiology of dental carries.
Sugar substitutes
 Artificial sweeteners are known as sugar substitutes.
 Have the advantage of adding sweetness to food without adding the extra calories to
food
Classification of sweetener
Based on nutrition composition
 Nutritive
 Non nutritive
 Types of nutritive sweeteners
 High fructose corn syrup
 Glucose
 Dextrose
 Lactose
 Maltose
 Honey
 Concentrated fruit juices
 Reduced energy polyols or sugar alcohols
 Sorbital
 Xylitol
 Mannitol
 Hydrogenated starch hydrolysates (HSH)
 Non caloric sweeteners
 Saccharin

42.  Aspartame
 Sucralose
 Neotame
 cyclamate
Based On Their Origin
a. natural sweeteners
 monellin
 licorice
 dihydrochalcone
 miraculin
b. artificial
 aspartame
 saccharin
 cyclamate
 sucralose
selection of sucrose substitutes
An ideal sweetener should have the following characteristics
a. should provide sweetness with no unpleasant taste.
b. Should have little or no calories
c. Should be non carcinogenic and non mutagenic
d. Should be economical to produce
e. Should not be degraded by heat when cooked ( heat stable)
Non caloric sweeteners have the following advantages
 Weight loss
 Dental care
 Good for people suffering from diabetes mellitus.
Some approved artificial sweeteners
a. Neotame.
b. Saccharin
c. Aspartame
d. Sucralose
e. Acesulfame K.
Saccarin
 Oldest artificial sweetener
 200-700 times sweeter than sucrose

43.  Available in liquid or tablet form as table sweetener
 Has slight after taste
Benefits
 Calorie free
 Pharmacologically inert and stable under moist conditions encountered in food
processing
 Heat stable
 Excreted almost without metabolic alteration , 75-95% in urine.
 It reduces the growth of S. mutans hence good in controlling dental carries
Draw backs
 Oral dose of 5-25gm daily may cause anorexia, nausea and vomiting
 Risk of bladde cancer. The risk of bladder cancer is 60% higher in men who use saccharin
tablets
Aspartame
 It is a combination of amino acids aspartic acid and phenylalanine
 180-200 times sweeter than sucrose
 Caloric value of 4 cal/gm
 Effective in enhancing acid fruit flavors and extending sweet taste as in chewing gums
 Brand names- Nutrasweet, Equal
Toxic Effects
 Acute
 Headache
 Dry mouth
 Dizziness
 Mood change
 Nausea
 Vomiting
 Thrombocytopenia
 Chronic
 Lymphomas
 Liver dysfunction
Disadvantages

44.  Risk of fetal abnormalities & mental retardation if blood levels of phenylalanine are not
carefully maintained below 12mg/100ml during pregnancy for persons with
Phenoketonuria (PKU )
Acesulfame
 200 times sweeter than sucrose
 Approved in 1988 by FDA for dry food products
 Used in yoghurt, refrigerated desserts and syrups
 ADI 15mg/kg/d
 Brand names- sunett & sweet one
Advantages
 Calorie free
 No evidence of carcinogenicity, cytotoxicity, and teratogenicity effects
 Excellent shelf life hence used in candies, canned foods and alcoholic beverages
Disadvatages
 Headache
Sucralose
 Discovered in 1976
 Non nutritive, non caloric derivative of sucrose
 600 times sweeter than sucrose
 Trade name SPLENDA
 Widely used in tea, carbonated beverages, coffee, chewing gum etc.
 ADI- 5mg/kg/d
 Advantages
 Non carcinogenic
 Zero calories
Disadvantages
 Diarrhea
 Dizziness
 Stomach pain
Neotame

45.  Newest of low calorie sweeteners
 8000 times sweeter than sucrose
 ADI- 2mg/kg/d
 Found in baked foods, soft drinks, chewing gums frozen desserts, jams jellies, gelatins,
puddings, processed fruits, toppings, and syrups,
Toxic effects
Headache
Hepatotoxicity at high doses
POLY ALCOHOLS
Sorbitol
 Occurs naturally in cherries, plums, pears, and apples
 Prepared from glucose by high pressure hydrogenation or electrolytic reduction
 Caloric value 4 cal/ g
 Recommendation by FAO 150mg/kg/d
Advantages
 Can be used by only 5-10 % of bacteria hence low acid production
Disadvantages
 Consumption exceeding >20gm can cause diarrhea. It acts as a laxative because of
osmotic transfer of water into the bowel.
Xylitol
 Obtained commercially from birch trees
 Naturally found in fruits and vegetables( strawberries, rasberries, plums), oats and
certain mushrooms,
 Commonly used by diabetic patients
 High doses causes diarrhea
 Good for plaque reduction
Advantages
 Decreases incidences of dental carries by killing the bacteria
Lactilol
 Sugar alcohol used as replacement bulk sweetener for low calorie foods
 40% as sweet as sucrose
 Provides 2.4 cal/g

46.  Used in sugar free in sugar free candies, cookies, chocolate and ice cream.
Advantages
 Highly stable, can be used in baking
 Promotes colon health as probiotic
 Laxative- prevents constipation
Disadvantages
 Cramping, flatulence and diarrhea
High Fructose Corn Syrup
 Mixture of fructose and glucose
 Produced from corn syrup
 2 common types
 HFCS 42= 42% fructose, 58% glucose
 HFCS 55= 55% fructose, 45% glucoe
Role of HFCS
 Baked goods- give brown crust, enhances flavor in fruit fillings
 Yoghurt- enhances flavor, controls moisture
 Canned and frozen fruit_ protects the firm texture of the fruit, reduces freezer burn
on frozen fruits
 Beverages- provides greater stability than sucrose in acidic carbonated sodas
Toxic effects
 Fat deposits in liver
 Narrowing of blood vessel
 Triggers asthma, food allergies, and damages immune system
 Accelerates the aging process
 Mercury poisoning as HFCS contains mercury
NATURAL SWEETENERS
Stevioside
 Found in leaves of Stevia rebaudiana
 Calorie free , non carcinogenic
 300 times sweeter than sucrose

47.  Brand names- pure via, truvia
Miraculin
 Shrub grown in west Africa produces berries that have property of causing sour
substances to taste sweet
 Active ingredient (miraculin) is a glycoprotein with molecular weight of about 44,000
 Effective in sweeting citrus fruits, berries, yoghurt etc.
 Trade name miralin miracle fruit drops
Licorice (ammoniated glycyrrhizin)
 Derived from licorice root(grycyrrhiza)
 50 times as sweet as sucrose
 Used as expectorant and pharmaceutical vehicles
 Reduce the solubility of enamel and prevent drop in pH during incubation of
saliva glucose mixtures
Monellin
 Red berries growing in grape like cluster
 Serendipity berries
 3000 times sweeter than sucrose
 Loses its sweetness within a day if left at room temperature
Tooth friendly sweet concept
 Started in Switzerland in 1989
 To provide consumers with easy guidance to tooth friendly ,” Happy tooth” label was
created.
 Tooth friendly bubble gum concept was presented by Beneo with palatinose.
 These chewing gums are derived from sugar beet
 Low glycemic index approved by EHA
 Reduced stickness