Basics of sugar technology

E material: Power Point Presentation in
Basics of Sugar Technology
Dr. RAMESH DURAISAMY
Associate Professor, Industrial Chemistry
College of Natural Sciences,
Arba Minch University,
Arba Minch (Ethiopia)

Introduction: Sugar & Sugarcane
Topics:
 Common Name, English Name and Botany of Sugarcane
 Classification of Sugarcane
 Centers of sugarcane origin
 Morphology of sugarcane
 Distribution of Sugar Industry on global screen.

Introduction of Sugar & Sugarcane (Shunkora)
Sugar
 Sugar, Chemist known as sucrose.
 One of the family of sugars also known as Saccharides in the grouping
called carbohydrates.
 Sucrose is disaccharide, which is a condensation molecule made up of Sucrose is disaccharide, which is a condensation molecule made up of
two glucose molecules.
 This is the plant product of sugar producing under photosynthesis:
12CO2 + 11H2O  C12H22O11 + 12O2
 Sugar produced from crops like sugarcane, sugarbeet
sweet sorghum, sweet potato, etc.

Sugarcane
 It is an important commercial crop.
 Main source of sugar produced for both export and domestic
consumption.
 Sugarcane is a very large tropical grass. It shows in all tropical and
subtropical countries.
Cont..
subtropical countries.
A hot, moist climate with a dry season is suitable for its growth, while
very low temperature or suddenly lowering temperatures may affect it
adversely.
 This is the plant consist a source of much of the World’s sugar. Widely
cultivated providing. Around 70% of the world sugar. Remain, 30%
sugar provided by sugarbeet.

Economic Uses of Sugarcane
 Cash crop gives ready cash to the farmers.
 Mainly used for production of sugar, jaggery and other sugar by-
products.
 Used for the preparation of juice, syrup and also for chewing purpose.
 Various by-products like bagasse, immature tops, molasses, press-mud
(filter cake) obtained from cane.
- Immature green tops are used as fodder.
- Bagasse (woody fiber) used as a fuel, production of paper & paper
boards, agricultural mulch, commodity chemicals, etc.
- Filter cake is used for animal feed, fertilizers, and source of
sugarcane wax.

 Trash is used for thatching (roofing) of huts, mulching and
composting.
 The stubbles (grains or stalks left in the ground) are used as fuel or
also used for making compost.
Botany of sugarcane
Cont..
 Family Name: Graminaceae.
 Local Name: Shunkora (in Amharic)
 Common Name: Sugarcane, noble cane, ikshu, khandha, sarkara,
paunda (in hindi), Poovan Karumbu (in Tamil)
 English Name: Sugarcane and Noble cane
 Botanical Name: Saccharum officinarum.

Classification of Sugarcane
 Main varieties are:
- Saccharum officinarum & S.edule
- S.robustum
- S.spontaneum
- S.sinense
- S.barberi
 S.robustum is generally regarded as the original species.
 S.spontaneum is a variety of cane with high regilience to diseases but
unable to produce sugar.
 S.sinense & S.barberi is also Indian & Chinese variety.
 S.officinarum is a variety of cane using in Ethiopia.

 Sugar production from cane began with cultivar of S.officinarum.
Hybrids
 Main varieties are actually hybrids whose type varies with soil and
climate conditions as well as local traditions.
 Hybrids were obtained by interbreeding of S.oficinarum with other
Cont..
varieties to increase productivity, resistance or climate adaptation.
 First hybrids consisted of cross hybridization between S.officinarum
and S.spontaneum to increase disease resistance of S.officinarum.
 Those hybrids were then interbreed back with S.officinarum to
recover the sugar producing genes lost by while the interbreeding with
S.spontaneum an unsweetened variety.

Origin and Distribution of Sugarcane (Shunkora)
 Old energy source and more recently, replacement of fossil fuel.
 First grown in Southeast Asia and Western India (around 327 BC)
 600 BC, sugarcane was first domesticated as crop in New Guinea.
New Guinean farmers & others chewed sugarcane for its sweet juice.
 Introduced, Egypt - 647 AD and in Spain - 755 AD Introduced, Egypt - 647 AD and in Spain - 755 AD
 Cultivation extended to all tropical and sub-tropical regions.
 Early in southeast Asia and elsewhere the farmers boiled the cane
juice down to a viscous mass to facilitate transportation.
 Earliest known production of crystalline sugar began in
India.
Exact date of the first cane sugar production is unclear.

Cont..
 7th century, Arab traders introduced sugar from south Asia to other
parts of the world Mediterranean, Mesppotamia, Egypt and Andalusia.
 Around 16th century Portuguese and Spaniards took into new world.
 18th century, Spaniards brought to the America, mainly Andalusians
from canary islands and Portuguese - Madeira islands.from canary islands and Portuguese - Madeira islands.
 1741, introduced to USA (Leuisiana).
 Christopher Columbus first took to the Caribbean during his second
voyage to the Americas; initially to Hispaniola (Haiti and Dominican
republic) islands.

Cont..
 Sugar (in the form of molasses) was shipped from Caribbean to
Europe or New England, where it was used to make rum.
 During 1836, sugarcane plantation done by most of the Asian and
African ethnic groups.
 Different species originated in different locations,
Saccharum.officinarum & S.edule - New Guinea
S. barberi & S.sinense – India
 70% of the sugar produced globally comes from S.officinarum and
hybrids using from this species.

Morphology of Sugarcane: Introduction
 Sugarcane – roots, stalk, leaves and inflorescence.
 Grows in clumps, consist a number of strong unbranched stem.
 Rhizomes forms under the soil which sends up
secondary shoots near the parent plant.
 Stems vary in color being green, pinkish or purple Stems vary in color being green, pinkish or purple
and can reach 5 m (16 ft.) in height.
- stems jointed, nodes being presented at the bases of the alternate
leaves.
- internodes contain a fibrous white pith immersed in
sugar sap, placed inside of plant cells.

Morphology of Sugarcane: Root system
 Development of the root system is
initiated soon after planting a
portion of stem (sett) with at least
one lateral bud.
 1st roots formed are sett roots,
which can emerge within 24 hours
of planting.
 Sett roots are fine and highly
branched, sustain the growing plant
in the first weeks after germination.

 Shoot roots are second type of root,
which emerge 5-7 days after
planting.
 Shoot roots are thicker and fleshier
Cont..
than sett roots and develop in to the
main root system of the plant.
 Sett roots continue to grow for a period of 6-15 days after planting.
Mostly senescing and disappearing by 60-90 days as the shoot root
system develops and takes over supply of water and nutrients to the
growing shoot.

Morphology of Sugarcane: Stem
 Solid, unbranched stem, circular in cross-
section, jointed with a node and an internodes.
 Node consists of a lateral bud situated in the
axils of the leaf, a band containing root
primordia, and a growth ring.primordia, and a growth ring.
 In certain varieties a bud groove or furrow can
be found on the surface of the internodes
above the bud.
 Normally only one bud occurs at each node,
and are situated on alternate sides of the stalk.

Cont..
 Several types of nodes and internodes are:
 Nodes are spaced around 15-25 cm;
but are much closer at the top of the
stalk.
 Nodes are also closer at the base (at
or just below soil level) where newor just below soil level) where new
tillers are being produced .
 Color & hardness of the stalks vary
with the variety, diameter can range
2.5 - 5 cm and hardness may vary by
growing conditions.

Cont.. Length and diameter of the
internodes are affected by moisture,
nutrition, climate, and temperature.
 Nodes are much harder than the
internodes.
 The juice containing sugar is stored
in thin-walled, parenchymatousin thin-walled, parenchymatous
tissue.
 Color of the stem depends upon many factors. Two basic pigments
are: red and blue anthocyanins in the epidermal cells and green
chlorophyll in the deeper tissue.
When both anthocyanin and chlorophyll are absent, the stem shows
yellow. The immature top joints are pale yellow.

Morphology of Sugarcane: Leaf
 Leaves are attached to the stem at the bases
of the nodes, alternately in two rows on
opposite sides of the stalk.
Each leaf consists of two parts: the sheath
and the blade or lamina.and the blade or lamina.
 Sheath is tubular in shape and broader at the
base than top. It tightly encircles the stalk,
and separated from the long, tapering,
pointed leaf blade by a ligule and one or two
dewlaps dependent upon the variety.

 Three main types of dewlaps: rectangular, deltoid and ligular
 Leaf has a strong midrib, usually white and concave on the upper
surface, and pale green and convex on the abaxial side.
Cont..

Morphology of Sugarcane: Inflorescence
 Flowering in sugarcane normally takes place
when there is a slowing down of the growth
due to approaching of shortening days.
 When a sugarcane has reached a relatively
mature stage of development, its growing
point ceases forming leaf primordia and
starts the production of an inflorescence. .
 Inflorescence or tassel is an open branched
panicle, also known as arrow. .
Flowering is known as arrowing.
Each tassel consists of several thousand tiny
flowers, capable of producing one seed.

Cont..
 The seeds are extremely small and weigh app. 250 per gram.
 For commercial sugarcane production, inflorescence development is
of little economic importance.
 Flowering is important for crossing and producing hybrid varieties .
 Generally, a day length close to 12.5 hours and night temperatures
between 20 - 250C will induce floral initiation.

Chapter: Sugarcane Cultivation Practices
Topics:
Soil& Sugarcane nutrition
 Climate conditions for Sugarcane
 Cultivation practices: Cultivation practices:
 Preparation of soil
 Sugarcane planting methods
 Planting in flat beds,
 Ridges and furrows method
 pit planting and bud transplanting

Soil Nutrients and its suitability for Sugarcane cultivation
 Crop stands in the field from 12 – 18 months
 Sugarcane grows extremely well in medium to heavy, well drained,
soils of pH 5.0– 8.5 and with high organic matter content.
 Water logged soils and soils of poor drainage are not suitable. Water logged soils and soils of poor drainage are not suitable.
 Growth of sugarcane will be poor in light sandy soils, Gypsum or
sulphur can be used soil reclamation of saline and/or alkaline soils.

Region Crop Nutrients (kg/ha)
Nitrogen
(N)
Phosphorous
(P)
Potassium
(K)
Inland Plant cane 100 – 120 40 100
Coastal
lowland
Ratoon 140 20 150
General fertilizer guidelines for N, P and K
lowland
Natal
midlands
Plant cane 80 60 125
Low veld Ratoon 120 40 175
Plant cane 120 30 125
Ratoon: Roots remain in soils and give rise to a ratoon crop in next years.

Main Composition of Sugarcane
Component Percentage
Fibre 11-16
Soluble Sugar 12-16
Non Sugar 2-3
Water 63-73

Nutrition's value of Sugarcane Juice
Component Amount (in gram)
Proteins 0.20
Water 0.19
Ash 0.66
Fat 0.09
Total calories 111.43Total calories 111.43
Total carbohydrates 27.40
Sugar 25.71
Riboflavin 0.16 mg
Niacin 0.20 mg
Pantothenic acid 0.09 mg

Component Amount (mg)
Calcium 32.57
Iron 0.57
Magnesium 2.49
Phosphorous 0.01
Potassium 162.86Potassium 162.86
Copper 0.09
Manganese 0.09
Pantothenic acid 0.09 mg

Sugarcane Crop Growth Phases
 Sugarcane has essentially
four growth phases viz:
germination phase,
tillering (formative)
phase, grand growth
phase and maturity.phase and maturity.
- Germination: 15-30 days
- Tillering: 50 - 120 days
- Grand growth
phase : 121 - 210 days
- Maturity: 210 - 365 days
 Growth phases would help in better management of the crop.

Climate Conditions for Sugarcane
 Grown in the world from altitude 36.70N and 31.00S, from sea level to
1000 m of altitude or little more.
 Essentially tropical and subtropical plant, long duration crop.
 Encounters all the seasons: rainy, winter and summer during its life
cycle.
 Primary climatic component that control cane growth, yield and quality Primary climatic component that control cane growth, yield and quality
are: temperature, light and moisture availability.
 Rainfall: Total rainfall between 1100 and 1500 mm is adequate.
• During active growth period rainfall encourages rapid cane growth,
cane elongation and internode formation.
• Ripening period high rainfall is not desirable because it leads to poor
juice quality.

 Temperature: Optimum temperature for germination of stem cutting is
320 - 380C. Practically stops germination when temp. is above 380C.
• Temperature above 380 reduce the rate of photosynthesis and
increasing respiration.
• For ripening, low temperatures about 120 – 140C are desirable, and
enrich the sucrose in the cane.enrich the sucrose in the cane.
• Temperature lower than 00C induces freezing of less protected parts
such as young leaves and lateral buds.
 Relative humidity: High humidity (80-85%) favors rapid cane elongation
during grand growth period.
 A moderate value of 45-65% coupled with limited water supply is
favorable during the ripening phase.

Sunlight: Sugarcane is a sun loving plant.
 It grows well in areas receiving solar energy from 18 - 36 MJ/m2.
 Sugarcane is capable of high photosynthetic rates and the process
shows a high saturation range with regards to light.
 Tillering is affected by intensity and duration of sunshine.
 High light intensity and long duration promote tillering while cloudy
and short days affect it adversely.
 Stalk growth increases when daylight is within the range of 10 - 14
hours.
 Increase in leaf area index is rapid during 3rd to 5th month,
coinciding the formative phase of the crop and attained its peak
values during early grand growth phase.
Reduced sunlight decreases yield and sugar content.

Soil Requirement
 Soil provides nutrients, water and anchorage to the growing plants.
 Soil types: ranging from sandy soils - clay loams & heavy clays.
suitable soil is deep clay loam.
 A well drained, deep, loamy soil with a buk density of 1.1 to 1.2 g/cm3
(1.3-1.4 g/cm3 in sandy soils).(1.3-1.4 g/cm in sandy soils).
 The optimum soil pH: 6.5, sugarcane tolerate growing in soil pH: 5-8.5.
 Soil testing before planting is desirable, as it helps in determining the
optimum quantity of macro and micro nutrients.

Soil Preparation
Good Land Preparation Poor Land Preparation
For higher sugarcane yields, optimum soil environment is an essential
pre-requisite.

Soil Preparation
Steps in Land Preparation Involve the Following:
 Sub-soiling to a depth of 50 to 75 cm to break hard compact sub-pan
layer. Breakage of hard pan muse be necessary.
 Ploughing to incorporate previous crop's residues and organic
manures [5-6 ploughings with atleast 2 planking's, must go 20-25 cm deep]
 Field layout: construct ridges & furrows and shape them.
Depth of furrows should be 25 cm. The furrow bottom should be
loosened to about 10 cm.
 Provide drainage channels, which are deeper than the furrows.
Drainage channels are particularly important in the high rainfall areas
to drain the excess water during rainy season.

Subsoiler - tillage toolSubsoiler - tillage tool

Planting of Sugarcane
Seed Selection
Sugarcane is depend upon variety, quality of
good seed. Selection of the stalks called sets.
The set should be:
 Fresh & Juicy
 Age should be of 9 to 10 months. Age should be of 9 to 10 months.
 Should be free from Pest & Disease.
 Eye buds should be fully developed.
 Select set from planted cane for seed and never from a ratoon cane.
 75,000-100,000 setts / ha or 200-250 mounds / ha seed is sufficient for early
sowing.

Planting of Sugarcane
Pre-planting / Seed treatment
- Seed treatment is necessary for prevention of fungal diseases.
Sets should be dipped for 15 minutes in a solution of Bavistin
100 gm and Malathion 250 ml in 100 liters of water.
- 48 hours soaking in water enhances germination.
- Soaking in hot water(50°C) for 20% minute greatly enhances
germination.
Planting pattern
 Three methods of planting:
- Planting in flat beds; Ridge or furrows planting method
- Paired row method ; Pit planting and
- Bud transplanting
germination.
- Indole acetic acid or nephthalene acetic acid enhances root growth.
- Acetylene promotes growth of cutting.

 In this method, shallow (8-10 cm deep).
 Distance between two rows : 75 to 90 cm.
 There should be adequate moisture in the
field at the time of planting.
Planting method: Flat bed method
field at the time of planting.
 3 budded setts are used, setts are planted
in them end to end system.
 Furrows are covered with 5-7 cm soil and
field is leveled by planking

Planting method: Ridges & Furrows method
 Three eyed (buded) sets are planted on ridges and furrows.
 Furrows are opened at every 75 - 90 cm according to soil type.
 3.5 – 4 MT (metric ton) seed is required per acre.
 Nowadays planting is done by two eyed sets keeping 4 - 6 cm distance
between two sets. For this 2 - 2.5 MT seeds required per acre planting.
 Instead of conventional method of planting, for maintaining optimum
plant population and easy management and higher population, furrow
method of planting is developed. This is the best method of planting.

Planting method: Paired row method
 Planting of cane sets are placed in
subsequent two furrows and next furrow
should be kept free of sets.
 row to row distance vary from 2.5’ - 3’
depends on soil type.depends on soil type.
 One Lateral (side) is sufficient to irrigate
both rows.
 Hence lateral to lateral distance varies from
7.5' to 9’.
Dripper to drip distance is 60 - 90 cm

 The cost of drip system is reduced by 25-30%.
 There is a saving in seed cost.
 The crop management becomes easy, crop gets sufficient
sunlight and hence grows faster.
 In this method cane produces more tillers and millable cane.
Along with proper water and fertilizer management practicesAlong with proper water and fertilizer management practices
increase the yield.

Planting method: Pit Planting
 This method, proved not only cost
effective but also increased the
yield two or three times compared
to the conventional row-to-row
planting.
 Average productivity about Average productivity about
70 MT/ha.
 Sets usually have three buds used
for planting.
 Sets are planted and raised in
round pits at the spacing 90 cm
between rows and 75 cm between
individual pits in a row.

Planting method: Bud Transplanting
 Sugarcane buds with half of its stalk can
be planted in small polyphone
/polyethylene sleeves filled with organic
manure and soil and after they sprouted
out, they can be transplanted in the main
field.field.
 The polythene is tore at the bottom for
the easy rooting. There is less
mortality about 5 % only.
 For gap filling during cultivation poly bag nursery should be raised with
single eyed set.
 Transplanting should be carried out in field after 45 - 50 days for
maintaining optimum plant population.

Chapter: Shredding of Cane & Extraction of Juice & Clarification
 Size Reduction: Shredding & Milling
 Extraction of juice :
 Maceration and Imbitions - cold
and hot water.
 Mill sanitationMill sanitation
 Measurement & weighing of juice
 Measuring tanks,
 Weighing machines: Hand operated, Semi-automatic and
automatic systems.

Preparation of Cane for Milling
Milling process may be separated into two steps:
- Preparation of the cane - breaking down the hard structure and
rupturing the cells.
- the actual grinding of the cane.
Preparation of the cane accomplished in many ways:Preparation of the cane accomplished in many ways:
1. By revolving cane knives - cut the cane into chips, but no juice extraction.
2. By shredders - tear the cane into shreds but no juice extraction.
3. By combinations of any or all of the process involved.
4. By crushers - break and crush the structure of the cane, extracting a
large proportion of the juice.

 Two sets of knives are used, revolving at speeds of 450-700 rpm.
 Various designs of knife blades developed such as Swinging blades of
the Ramsey type, serrated knives, double edged knives, and self-
sharpening arrangements as:
Revolving Cane Knives
7/18/2018
48Typical Knife installation
Swinging Knives

Shredders
 Shredder tears the cane chips (come from the knives) into shreds (small
pieces) without extracting juice .
The shredder is a large powerful hammer mill that shreds the cane into a
small fibrous material.
 Silver shreder system, a buster and a fiberizer are the equipments used for
the preparation of cane:
Cane Buster (Silver) Fiberizer (Silver)

 Unigrator, developed in 1970’s functions as both chopper and
fiberizer.
It used for cutting and shredding with one operation, achieve the open
cell of prepared cane around 80 - 85%.
Chopper fiberizer (Unigrator)

 The Tongaat shredder incorporates in most of the countries to
departures from the traditional type of construction.
Tongaat shredder (A) Shredder side section
(B) Shredder feeding

Various factors influencing the designing of a shredder to achieve a
particular level of cane preparation.
The rating of various shredder configurations is:

MILLING TANDEMMILLING TANDEM
• Used to extract the juice
from crushed cane.
• 3 roller mills connected in
series
– Top roller
– Feed roller– Feed roller
– Discharge roller
• 3-7 in number.
53

Milling machinery
• Composed of three rollers arranged in triangular form.
• A set of 3 - 7 set of three-roller units described 9-roller to 21-roller
mill are in use.
• The three rolls - the top roll, the cane roll (entering) or feed roll, the
bagasse roll or discharge roll.bagasse roll or discharge roll.
• Two bottom rolls are rigidly fixed in position; the top roll, controlled
by an hydraulic ram, may rise or fall, or float, with variations in the
feed cane.
 The crushed cane is guided from the opening between the top roll and
feed roll to that between the top roll and the discharge roll.

 Under opposite rotation of top roll (anticlockwise) and bottom rolls,
(clockwise ) the efficient juice extraction takes place.
Pressure feeder with spikey toothed rollsA Four-roll mill

Extraction of Juice: Milling Process
 Using the equipment already described, prepared cane with 70 - 75%
of its weight in juice, is being passed through the crusher & mills.
 No reasonable amount of grinding or pressures can reduce the final
product of woody fiber (bagasse) and juice.
 Universal practice to add water or thin juices to the bagasse after each
mill, thus diluting the contained juice and increasing the extraction.
 This concern to maximize the efficient extraction, use of water is
termed maceration, imbibiions , or saturation.

Extraction of Juice: Maceration, Imbibition, Saturation
Maceration or saturation are as synonyms of imbibition.
 Maceration : Defines, a form of imbibition in which the bagasse is
steeped in an excess of fluid. It further defines imbibition as
 Imbibition: The process in which water or juice is applied to a bagasse
to enhance the extraction of juice at the next mill.
The term also applied to the fluid used for the purpose.

 Three types of imbibition may be employed:
1. Simple imbibition - rarely practiced in modern installations, water
only is applied to the various mills.
2. Double imbibition: Now almost obsolete, water is applied to the
bagasse from the next to last two mills and combined thin juice from
the last two mills is returned to the earlier mills in the train.
3. Compound imbibition: Applicable to trains of four or more mills.
• Water is applied to bagasse going to the last mill, the last mill
juice is returned to bagasse going to last mill;
this juice in turn goes back to bagasse from the preceding mill,
and so on:

Hot or Cold Imbibition
 Whether to use hot or cold imbibition, water is a matter of some
controversy, but hot water (176 F or 800C) is generally preferred
thought the world.
 Arguments for hot water are: some fuel economies, rupture of some
cells by heat (above 160 F or 700C), slight evaporation from the
bagasse in transit, the use of return condensate from evaporatorbagasse in transit, the use of return condensate from evaporator
bodies, and a slight gain in extraction, not always detectable.
 Even under the best conditions, the imbibition process is not entirely
effective and it does not dilute all the juice in the bagasse.
 Disadvantages of hot imbibition: more extraction of gums and
impurities from the trash; the mills do not take the feed as well, and it
facilitates the growth of microorganisms that produce dextran.

Mill Sanitation and Sugar losses around mills
 The sugar losses caused by old-style juice strainers, but other losses
occur in and around the mills,
particularly if proper attention is not paid to cleanliness and sanitation.
 Modern mill designs avoid all projecting bolts and dead corners in
juice troughs.juice troughs.
 Bagasse conveyors, carriers, and all moving parts about the mills are
made more accessible for cleaning.

 Warm cane juice offers an ideal medium for the growth of
microorganisms; to avoid such growth, juice must be moved promptly
to the clarification station, where sterilization occur by heat.
 High pressure hot water hoses with small nozzles used for every
3h to reduce losses by dislodging accumulations around juice
strainers, elevators, and other trouble spots.
 In addition to cleanliness, the application of modern bacteriostatic
compounds is beneficial.
 Chemical treatments can be applied while the mills are grinding cane.

Weighing of Raw Cane Juice
 All incoming raw juice must be weighed for,
- Estimation of mill performance and extraction,
and boiling house efficiency.
 Standard procedure is to weigh cane juice before it is limed, and before
enters into a warehouse for storage.enters into a warehouse for storage.
 If mixed juice is not weighed, the whole operation of the raw sugar
house will be on guesswork,
and losses of sugar will not be accurately estimated and located.

 Raw juice can be measured with a flow-meter instead of being weighed
in a batch operation, but this method is not recommended.
- Flow meters are satisfactory for measuring water or clarified juice,
but raw juice carries a large amount of suspended matter which may
affect the accuracy of the flow-meter.

Manual Weighing of Cane Juice
• Several years ago, mixed juices were weighed manually, using a scale
with two weigh-tanks.
- While one weigh-tank was being filled, weighed and the weight
recorded, the other would be discharging juice.
- Scale was set to weigh a predetermined weight of mixed juice, and
the weight of each weight-tank is more or less the same.
- Some amount of juice and foam remained in the scale tank, but the
scales were not tarred after weighing.
- Operator rinsed the weigh-tanks with water from time to time.

Weighing of Cane Juice by Automatic Scales
• It is a better alternative.
 Elimination of the juice scale is detrimental to a sugar factory, because
without it no factory control is possible.
 Use of an automatic scale for weighing cane juice is advisable.
 There are many types of automatic scales are now available.
 Maxwell-Boulone Weigher
 Howe Richardson juice scale
 Servo-Balans Duplex weigher
 Toledo Model Automatic Scale

Weighing of Cane Juice: Maxwell-Boulogne Weigher
• It has a single weigh tank, operates automatically by gravity and no
power is required.
 The same weight of juice is discharged at every weighing and an
automatic counter registers the number of weightings'.
 Weight tank is provided with a baffle plate which retains a certain
amount of juice and foam .
 This scale is provided with a raw juice supply tank and a small liming
tank, which measures a predetermined amount of milk of lime and
discharges it simultaneously.
 It is built for varying capacities, and it is very practical for weighing
raw juice.

Weighing of Cane Juice: Howe-Richardson Scale
• It is also has a single weigh tank, operates manually or automatically.
 Predetermined desired weight set on an automatic dial, and the scale
will discharge nearly the same amount of juice on each weighing with
automatic cut-off controls.automatic cut-off controls.
 The weight and tare can be recorded and exact weight of juice can be
calculated.

Weighing of Cane Juice: Servo-Balans Scale
• It is an excellent scale for weighing cane juices built by N.V.Servo
Balans, scale makers in Holland.
• Working the Duplex weigher, based on the servo principle which uses
the slight force needed to move a slide valve to create a greater force
to move pistons.
• Machine is operated by two cylinders using oil pressure.
• Main characteristics: Each weighing cycle the weigh tank is weighed
twice: first when filled and then after emptying, which is tarring of
tank.
 Accuracy of this scale in one in a thousand, and it can be equipped
with a printing mechanism.

Weighing of Cane Juice: Toledo Scale
• Automatic juice scale with two weigh tanks.
• Each weigh tanks is weighed automatically or can be operated
manually with a push buttons.
• In the event supply valves do not close, an overload switch operated
from the tare beam lever energizes an alarm horn.
• Scales are interlocked for alternate operation.
 Tare poise on each scale should be set to allow sufficient heel in the
weigh tanks.
This will eliminate inaccuracies in load weight caused by juice
sticking to the sides of the tanks.

Chapter : Clarification
• Primary objective is to remove impurities from the juice.
• The degree of clarification has great bearing on the subsequent
stations of the factory,
- affecting the pan boiling, the centrifuging, the quality of
the products, and most important of all to maximize the yield ofthe products, and most important of all to maximize the yield of
raw sugar.
To remove non-sugars and impurities
 Liming
 Sulphitation
 Phosphatation
 Carbonation

Clarification of the juice is need for two purposes
1. Removal of impurities
 To precipitate dissolved inorganic non-sugars present in the juice
in colloidal state thereby to increase the % of available or
crystallizable sugar.
 To separate insoluble solid matters suspended in the juice in
colloidal state rendering the juice opaque, viscous and dark color.
These impurities are separated along with non-sugars precipitated
by the action of lime and heat, leaving the juice transparent.by the action of lime and heat, leaving the juice transparent.
2. Bleaching effects
 After the impurities are removed by the chemical treatment of the
juice, bleaching is done to render the juice brilliant and light in
color as this process is necessary for the manufacture of white
sugar but is not much importance for the raw sugar.
 SO2 is the chief bleaching agent used in sugar house practice

Clarification of Juice: Liming

 The limed juice enters a gravitational settling tank: a
clarifier.
 The juice travels through the clarifier at a very low
superficial velocity so that the solids settle out and exits
clear juice.
 The mud from the clarifier still contains valuable sugar so it
is filtered on rotary vacuum filters where the residual juice
is extracted and the mud can be washed before discharge,
producing a sweet water.
 The juice and the sweet water are returned to process.

 The juice from the mills, a dark green color, is acid and turbid.
 The clarification (or defecation) process is designed to remove
both soluble and insoluble impurities (such as sand, soil, and
ground rock) that have not been removed by preliminary
Clarification of Juice: Liming
ground rock) that have not been removed by preliminary
screening.
 The clarification of mixed juice is commonly referred to as the
'simple defecation process' in which heat and lime are used to
produce a clear juice suitable for further processing.

• Carbon dioxide and the milk of a lime are added to the liquid
sugar mixture and it is heated to the boiling point, and begins
clarifying.
• As the carbon dioxide travels through the liquid it forms calcium
carbonate, which attracts non-sugar debris (fats, gums, and wax)
from the juice, and pulls them away from the sugar juice.
• The juice is then pushed through a series of filters to remove any
remaining impurities.

• The muds separate from the clear juice through sedimentation. The
non-sugar impurities are removed by continuous filtration.
• The final clarified juice contains about 85% water and has the same
composition as the raw extracted juice except for the removed
impurities.
• Results of clarification are:
rapid settling of the precipitate;
light-colored clarified juice with pH is 7.00 and free of turbidity;
a maximum concentration of the settled muds.

 For a first class lime, the CaO content should be 85-90% and 2% of
each for moisture, SiO2, Fe2O3 and Al2O3, MgO, and carbonates.
 The amount of lime to be added to the juice varies with differing
Quality and Quantity of Lime
conditions and in different countries.
 Possibly 1.25 lb CaO per tone of cane would be a rough range.

 Addition of the correct amount of lime is the basis of good
clarification.
 Too little lime will give poor settling and cloudy juice with possible
losses by inversion.
 Too much lime cause darkening of the juices, increase in gummy
Effect of Lime
 Too much lime cause darkening of the juices, increase in gummy
substances in low grade products, increased ash because of dissolved
lime salts, and high molasses output.
 Lime will dissolve in sucrose solution forming calcium saccharate, a
true solution , which can be handled with none of the problems of
handling a slurry.

 High liming is to be avoided; and if clear juice cannot be obtained by
simple defecation except by liming to high alkalinities, the addition of
phosphate or some other modification of the process should be
employed.
 The addition of polyelectrolyte's has proved valuable as an adjunct to
the heat and lime process.the heat and lime process.

 Optimum pH to which juice should be limed is dependent on many
conditions and varies with the location of the factory, the variety and
maturity of the cane, capacity of the settling equipment, and other local
conditions.
 The minimum of lime that will give clear juice with a final reaction close to
7 pH is most desirable. In areas where cane is harvested not in full maturity
Effect of pH on Liming
7 pH is most desirable. In areas where cane is harvested not in full maturity
when harvested, the organic acids in juice keep the pH below 7.0.
 Highly acidic or alkaline juice forming bisulphite or bicarbonate decompose
at higher temperatures and the decomposition products deposit on the
heating surface having adverse effect.
 The pH of the juice recommended is either neutral or slightly acidic or
alkaline in the range of pH 6.9 - 7.1.

The effect of heat
 The fact that floc formation can be initiated by heating alone indicates
that the effect of temperature has a significant part to play in
clarification.
 This is attributed primarily to protein coagulation. This is attributed primarily to protein coagulation.
It is generally believed that superheating is not advantageous and that
temperatures just above the boiling point (103°C) are the maximum
for good practice.

Steps in the process and the modifications in liming
 Method of adding lime: as milk, in batches or continuous.
 Regulating quantity of lime: periodic tests; continuous recording of pH;
automatic addition through pH control.
 Time of adding lime: before heating; “delayed liming” (increased
reaction time before heating); fractionally before and after heating.
 Temperatures: Boiling; superheating.
 Treating juices from different mills: single clarification; compound and
separate clarification.
 Method of settling: open settles; continuous and closed settles.
 Treatment of scums: single filtration; double filtration; returning to
mills; redefecation separately or with in juices, as in compd. clarification.

Sulfitation of cane juice
 Use of SO2 in addition to lime in the manufacture of raw sugar is not
general in modern practice.
 The extra cost of sulfitation, increased sealing in heaters and evaporators,
and higher ash in raw sugars are reasons for the discontinuance of
sulfuring in raw sugar production.
These considerations do not apply to the production of white sugar byThese considerations do not apply to the production of white sugar by
sulfitation.
 Sulfitation processes are subjected to almost as many modifications as
simple defecation . The variations may include the following:
- modifications of the sequence of addition of lime 2 and SO ( liming
first, sulfiting first, simultaneous addition of lime and gas,
fractional procedures).

- Temperature modifications (sulfiting cold or hot, stepwise heating)
- addition of reagents (batch, continuous, with either manual or
automatic control).
 The most commonly used methods discussed here:

Cold Sulfitation
 The cold raw juice is pumped through a tower or box with a counter-
current of SO2 to absorb as much gas as possible (acidity 3.0-4.0 ml
0.1 N alkali for 10 ml of juice; pH 4.0 or below).
 Liming to slight acidity (pH about 6.5) is followed by heating, settling, Liming to slight acidity (pH about 6.5) is followed by heating, settling,
and decanting as in the defecation process. Evaporation to a thin syrup
follows, and the syrup is settled for 6-24 h before vacuum pan boiling.
 One boiling, yielding a near-white sugar that is heavily washed in the
centrifugal, is frequently followed by a second boiling to a raw sugar.

 The "boil-back" molasses is allowed to settle for several weeks before
it is placed on the market. The success of the process is largely
dependent on the quality and price of this molasses.
 Sulfitation can also be carried out by injecting SO2 (industrial liquid
SO2 in cylinders) into the cold raw juice to a level of about 400 ppm
SO2.
 This is for the production of raw sugar and A molasses.
The A molasses is inverted to yield a sucrose-invert ratio of about 1:1,
giving a total sugar of 65% at 80 Brix, with an SO2 level of 30-40
ppm.

Sulfitation After Liming
 This process is termed alkaline sulfitation as opposed to acid
sulfitation.
 It uses about 8 gal (30 litre) of 26 Brix milk of lime per 100 gal (378
litre) of juice giving a large excess of lime.
 Sulfitation is then carried out to about pH 7.5 producing a heavy
precipitate that may be removed with settling and decantation.
 Heavier liming (10-12 gal, 38 - 45 litre), will result in a precipitate that Heavier liming (10-12 gal, 38 - 45 litre), will result in a precipitate that
permit filter-pressing.
 After evaporation the syrup is cooled and sulphited to slight acidity
(pH 6.5).
 Treating diffusion juice with lime and then sulfitation decreases the
colour of syrup, raw sugar, and refined sugar by 25% 46% and 35%
respectively.
 The filterability is improved and molasses purity is lower, giving better
sugar recovery

Hot Sulfitation
 Hot sulfitation serves to reduce the solubility of calcium-sulphite,
which is more soluble at low temperatures, the minimum solubility is
at about 75°C (167 °F).
 The juice is first heated to this temperature then sulphited and limed
boiled, and settled.
 Harloff's process is a hot treatment procedure in which the juice is Harloff's process is a hot treatment procedure in which the juice is
heated to 75 °C and the lime and SO2 are added simultaneously in
such a way as to maintain the reaction acid to phenolphthalein and
alkaline to litmus (pH about 7.4-7.8), except toward the end, when a
quantity of lime is added to attain a strongly alkaline reaction (pH
10+), after which the sulfitation is completed to neutrality to litmus
(pH about 7.2).
 As in all other similar processes, the juice is finally brought to boiling
temperatures in juice heaters and settled.

Continuous Sulfitation
 This process practiced from the earliest days of the use of SO2, since
the juice and gas were simultaneously passed through a tower in a
continuous countercurrent stream, after which the acid juice is limed
in a batch process.
 Continuous sulfitation means the continuous addition of SO2 and lime Continuous sulfitation means the continuous addition of SO2 and lime
to the constantly flowing stream of juice.
 Marches shows many different procedures with diagrams indicating
construction details, methods of lime and gas addition, baffles to
ensure proper circulation and other details.
 Many of the continuous liming processes may have different fractional
procedures, but are not in general practice.

Middle Juice Carbonation
 Middle juice carbonation first treats the juice with lime and heat as in
the simple defecation process, then without removing the precipitate,
concentrates the juice to 40 Brix and applies the carbonation process
to this concentrate.
 The merits on middle juice carbonation: The merits on middle juice carbonation:
- saving of lime as high as 45.4%
- evaporator cleaning chemicals were reduced by 61 to 87% because
of higher sulfate removal, therefore less scale formation;
- better sucrose recovery, higher sugar yield, and better sugar quality
were attributed to better removal of nonsugars.
 The higher Brix of middle juice did not affect filterability.

Modern Development in the Carbonation Process
 The factors determining the results of the carbonation process with an
exact measurement of the temperature, rate of flow, effect of mixing
and so on.
 For a good filtration, as the first step, it has been found necessary to
add lime to a rather high alkalinity, pH 10.5 to 11.add lime to a rather high alkalinity, p 10.5 to 11.
 This reaction must be keep for a short time, say 5 min., during which
period a precipitate of phosphate of lime is formed and well
coagulated.
 In the second stage of carbonation, on addition of CO2, this precipitate
acts as a nucleus by which a sedimenting, good filtering, coarse
precipitate is formed.

 The second precaution is to prevent too high a pH during the first
carbonation, since otherwise compounds between CaO, CaCO3 and
sucrose may be formed:
2Ca(OH)2 . 3CaCO3 . C12H22O11
 This sucrocarbonate of lime is viscous and insoluble. It takes a certain
time to decompose, thus increases the losses of sucrose in the
discarded filter mud.

Chapter: Evaporation
 Remove water from the solution, yield crystalline product.
 Done in two ways:
- evaporator station to concentrate solution, proceeds in multiple effect
evaporators.
- vacuum pan to crystallize the sugar from solution, performed in single- vacuum pan to crystallize the sugar from solution, performed in single
effect vessels by varying conditions of,
- temperature
- absolute pressure and
- supersaturation.
94

 Evaporator station, 90% of water removes from clarified juice.
Increases the solids from 15 Brix to 65-70 Brix.
For the refining of raw sugar, two evaporator stations are employed.
 First concentrates high quality liquors in vacuum pans.
Liquor Brix is increased from 60-65 to 65-72.
 Second evaporator station concentrates sweet water (mud wash).
95

Evaporation: Single and Multiple Effect
Single-effect Evaporator:
Simplest form, closed pressure vessel divided into two sections.
 One section is connected to steam source & other is partially filled with water
(juice).
 If the steam temperature is higher than the boiling point of the water (juice),
that occur:
- Steam will condense and transfer heat to the water (juice).
- Water (juice) will be boil and will drive off water vapor.
96

Simplest multiple-effect Evaporator:
 Two single effects connected in series, the vapor outlet of the first vessel
being the steam source for the second vessel.
 Extended to three, four and more effects.
 Basic requirement is that the boiling temperature of the liquid in each effect
must be lower than the steam temperature, that entering the effect.
 This temperature difference provides the driving force for heat transfer from
steam to liquid.
97

Juice Heaters
 Juice or liquor heating is done in shell and tube heat exchangers.
Shell and Tube heater Designs: Basic design calculations for heaters
follow the heat transfer equation:
Q = U A t
Where, Q – heat transferred (Btu/h)Where, Q – heat transferred (Btu/h)
U – overall heat transfer coefficient (Btu/h.F.ft2)
A – heat transfer surface area (ft2)
t – temperature difference between steam and liquid (F)
t is the logarithmic mean temperature difference (LMTD).
99

Where, tin – temperature difference between steam and cold liquid
entering the heater.
tout – temp. difference between steam and hot liuid leaving the
heater.heater.
100

 The use of 16 gauge 1 in., O.D. tubs with an inside heating surface of
2277sq ft per linear foot (0.0694m/m) would require.
452 / 0.2277 = 1985 linear ft (605 m) of tubing
Juice flow = 111,000 / (66) (60) (60) = 0.467 cu ft/sec. (0.013 m3/sec).
 At velocity of 7 ft/sec (2.13 m/sec), the flows area required for juice flow is:
0.467/ 7 = 0.667 sq ft. (0.006 m2)0.467/ 7 = 0.667 sq ft. (0.006 m )
 Flow area of line tube (1 in., O.D. x 16 gauge) is 0.594 sq in.
(3.83 cm 2) or 0.0064125 = 16.18 or 16 tubes.
102

Plate Heat Exchangers
 Widely accepted for heating and cooling of liquid sugars and invert
the sugar solutions.
 Made up of a number of thin dimpled sheets, separated by gaskets.
 Plates are corner ported to provide the desired flow pattern.
 Units are versatile, providing countercurrent or concurrent liquid-liquid
heat exchange, or vapor-liquid heat exchange, or combined heating
and regenerative cooling.
105

 Plate heat exchangers, are very thin film of liquid in each pass, have
very high heat transfer coefficient (U) values.
 Temperature and pressure limits are not exceeded.
 Pressure up to 300 psi can be accommodated, but most units are Pressure up to 300 psi can be accommodated, but most units are
designed to 85 - 140 psi.
 Temperature limits are usually set by gasket material; 160 F for
neoprene, 280 F for silicone, and 390 F for asbestos.
106

Vacuum Pan Station
 Function of the vacuum pan used to produce and develop
satisfactory sugar crystals from the syrup or molasses.
 Desirable quality of raw sugar is influenced by the design and
operation of pans.
 Concentration of the products used in the pans usually 60-65 Brix,
and may reach 74 Brix in refinery work.
 High densities reduce the steam consumption and cut down the
duration of cycle, but make satisfactory control operation that
involving the danger of producing conglomerates and false grain.
108

Types of Pan
 Two types:
Coil Pans: Operate satisfactorily on live steam, and
Calandria pans: use low pressure exhaust steam or vapors robbed from
the first multiple effect or from a pre-evaporator.
Coil pan has three main disadvantages:
 Restricts steam economy by having to use live steam. Restricts steam economy by having to use live steam.
 Maintenance costs are high.
 To improve circulation, mechanical circulators cannot be installed; only
perforated steam coils provide limited added circulation.
For these reasons, no coil pans have been built for cane sugar for many years.
109

Definition used in Pan Boiling
 Syrup is the concentrated juice from the evaporators.
 Mixture of sugar and mother liquor discharged is called massecuite,
the mother liquor molasses.
 Seed magma - Low grade sugar with syrup or molasses stored in
crystallizers.
The quantity used for each strike called a “footing”, is enough to
cover the calendria.
 Strike: Each panful of massecuite.
 Transferring massecuite from one pan to another is called cutting.
 Graining: Process of initiating the formation of sugar crystals.
110

Pan Circulation & its Speed
 Importance: Most important characteristics of vacuum pan operation
are circulation and temperature conditions.
An investigation of these features was made by Webre. According
his findings and conclusions:
 The speed of massecuite travelling through the tubes of calandria
type: Speedtype: Speed
Time ft/sec. cm/sec
First hour 1.53 46.6
Second hour 0.63 19.3
Third hour 0.15 4.6
Fourth hour 0.03 0.9
Fifth hour 0.02 0.6
Sixth hour 0.01 0.3 111

Slurry: Liquid (juice) containing solid (sugar) particles.
Slurry Parameters:
1. Particle size and Distribution:
Particle size d50 (d85) is a measure of the % of particles present in the
slurry with a certain size.
 The value is determined by sifting (separate) the solids through screens
Chapter-VI Cane juice Slurryc
 The value is determined by sifting (separate) the solids through screens
and then weighing each fraction.
 Drawn a sieve curve and the % of particles
of different sizes is determined.
Ex: d85 = 3 mm means that 85% of the particles
have a diameter of 3 mm or less.
112

2. Concentration of solids: It is measured as a volume %, Cv, and a
weight %, Cm.
113

Types of Slurry
 Slurries can be divided into ,
Settling and non-settling types.
Non-settling slurry: Solids do not settle to the bottom
but remain in suspension for a long time.
- It acts in a homogeneous, viscous manner.
- Particle size is less than 60-100 microns.
Settling slurry: Settles fast during the time relevant
to the process, but can be kept in suspension by
turbulence.
- particle size: greater than 100 microns.
114

Process of Sugar boiling
 First step is making of grains.
 This is done for each strike (painful massecuite) in cane sugar
refineries and in beet factories.
 In raw sugar industry, grain is made for low grade strike only.
 Preferable to make grain at a vacuum. Preferable to make grain at a vacuum.
 Depending on purity, operating temperatures is applied, 150-160 F.
 At these temperatures the viscosity will be lower and the rate of
crystal growth become faster.
116

Sugar boiling: Pan seeding
 Best method of obtaining good grain.
 Adding the seed at proper moment, the full amount of predetermined size of
grains forms in the finished.
No chance to form grain at any time in the pan, because the concentration
must be held in the crystal growing or metastable phase.
 In boiling, seed to be added as soon as the saturation point is reached.
117
 To determine the proper amount of fines to introduce into a pan to make a
strike of sugar of a certain size, proceed the followings:
(i) Find the weight of sugar expected from the strike.
(ii) Count and weigh about 500 crystals of the grade sugar.
(iii) Count and weigh 500 crystals of the seed power to be used.
(iv) Dividing (iii) and (ii) and multiplying by (i) gives the weight of seed.

 After this has been done and tried, minor corrections can be made
to take care of variations.
 Pan seeding is used universally by refineries in the production of
large grain sugar such as sanding, manufacturer’s standard, medium
and coarse grains.
118
 With the right amount and size of seed for the grain used, that produce
specialty sugars with much more regular crystals, entirely free from
from conglomerates;
This is almost impossible by other methods.

False grain and conglomerates
 Conglomerates/mounted grain/married grain/rolled grain, that mean a
grouping of a number of crystals that then grow together as one.
 Unless pan seeding is used, the formation of grain is arrested by increasing
the pan temperature, by dilution, or both.
 Even if all the grains not destroyed, part of it may be, and thus leaving an
insufficient quantity and requiring additional nuclei to make up the loss.
 Fundamentally, after all the grain has obtained, the concentration must be
brought back to the metastable or crystal-growing phase.
 If the concentration is too high, false grain or smear will form & must be
dissolved by dilution, preferably with water.
119

 Once conglomerates formed, that remains to the end of the strike.
 These group of crystals are objectionable because impurities and dirt
lodge in the crevices (gap), preventing proper washing and yielding a poor
product of high color and low filterability.
 In refined and raw sugars, conglomerates lower the quality of the sugar
and make more difficult on drying in the granulators.
120

Cause of conglomerates
 Conglomerates form more readily at higher purity
Low purities almost never conglomerate.
 In selecting fine for seeding, if these are conglomerated, the resulting final
product also get conglomerated, since conglomerates never destroyed.
 Conglomeration takes place at the upper edge of the metastable zone,
just before the occurrence of false grain.
In other words, if false grain has been formed, the occurrence of
conglomerates is almost certain.
121

Controlling of Conglomerates
 Fines used for seeding should be prepared by crushing well-formed
coarse sugar. The broken pieces will not be conglomerated.
They will revert to perfect shape faster because of the physical forces
compelling definite crystal form.
 If grain is started by seeding on low purity molasses with powder fines,
there will be no conglomerates whatever.
 This has important application in the new two-boiling pan systems.
122

Cause of false grain formation
 Due to sudden fall in steam pressure or sudden rise in vacuum,
the temperature of the boiling massecuite is lowered that induces the
formation of new grains.
 Due to introduction of a large charge of syrup or molasses in the pan.
 Due to formation of bold grains and fast boiling.
 Due to careless operation, when the degree of supersaturation is pushed
too high after the granulation period.
 Due to faulty circulation: This can be responsible for high supersaturation
 Due to very high viscosity: Has the greatest deterrent effect in sugar
boiling operation.
 Due to high turbidity of juices or syrups.
123

Crystallization of sugar
Chapter: Crystallization, Molasses & Refining of Raw sugar

Theory of Crystallization
 Crystallization is a method of formation of solid particles within a homogeneous
phase.
 Crystalline solid substances are prepared either by solidification or by
precipitation.
 Crystallization is a thermal separation, and yields a solid product.
 Crystallization is a highly selective process and operates at lower temperatures.
125

 The crystallization process consists of two major events, nucleation and
crystal growth.

Crystallization Zone
Super saturation can be achieved by adding more of a substance (to a solution)
than can normally be dissolved. This is a thermodynamically unstable state,
achieved most often in crystallization by vapor diffusion or other slow evaporation
techniques.
Zone 1 - Metastable zone.
The solution may not nucleate for a long time but
this zone will sustain growth.this zone will sustain growth.
It is frequently necessary to add a seed crystal.
Zone 2 - Nucleation zone.
Crystals nucleate and grow.
Zone 3 - Precipitation zone.
Do not nucleate but precipitate out of solution.

Crystallization of sugar from cane slurry
 After concentrating the cane juice, the subsequent process is used to turn
the thick juice into crystal form.
 Pan boiling is difficult and requires much skill and experience to make
crystals of required number and predetermined size, character, free from
false grain and conglomerates.false grain and conglomerates.
 Once the crystals are formed, the boiling operation is conducted in such a
way that grains already formed and that none of the existing grain is
dissolved.
128

INSUGARINDUSTRY…
 Crystallisation is the process just after evaporation.
 During evaporation the clarified sugar cane juice is boiled in evaporators
which remove most of the water leaving a thick syrup.
 Then in the crystallization process the syrup is boiled at low temperatures
under partial vacuum and some seeding's are added which causes the
development and growth of sugar crystals and the outcome is called
massecuite (raw sugar crystals mixed with molasses).
 The sugar crystals and molasses are then separated in centrifugals.

 There are normally 3 vacuum pans used namely A, B and C.
 Syrup coming from evaporators enters pan A, where boiling takes place and
crystallization begins giving a thicker liquid (massecuite) which comes out
and enters the centrifuge.
Schematic representation of sugar crystallization unit. (1) Syrup (liquor A); (2) massecuite A; (3)
raw sugar (A); (4) mother liquor A used as feed liquor B; (5) massecuite B; (6) sugar B recycled as
magma A; (7) mother liquor B used as feed liquor C; (8) magma C (prepared in batch seeding
crystallizer); (9) massecuite C; (10) sugar C recycled as magma B; (11) molasses.

 During crystallization, it is necessary to initiate the
formation of sugar crystals, by the formation of
nuclei through the seeding system.
 Various seeding techniques are includes:
1) Traditional (secondary, or shock) seeding
2) Full seeding :2) Full seeding :
a. seeding with slurry
b. seeding with footing magma

 In shock method, the syrup entering into vacuum pan A is concentrated and
a small charge of powdered sugar is introduced;
boiling is continued until a proof slide appears to have sufficient grain.
Suppose, the sugar by its mere presence "shocked" the unstable syrup into
spontaneous nucleation to form most of the needed grain.
The same procedure is carried out with the other pans.
 The shock seeding method is successfully carried out by seeding the The shock seeding method is successfully carried out by seeding the
oversaturated syrup in the pans with a measured amount of standardized
fine ground sugar slurry.

 The grainy nature of the crystallized sugar is
determined by many factors, that includes:
• Degree of super-saturation
• Rate of cooling
1. Quality of the crystals is determined by the supersaturation and pan circulation
maintained all over the strike, while the time needed to reach the required
product crystal size is determined by the linear speed of crystal growth.
• Rate of cooling
• Degree of cooling
• Timing, rigor and length of stirring
• Temperature at stirring
• Seeding
• Blend of sugars present
• pH
• Presence of crystal growth inhibitors

Factors Affecting Crystal Growth
 Increase the relative velocity of crystals and mother-liquor doubles the crystal
growth.
A mechanical circulator promotes the relative velocity of crystals in pan.
 Impurities (non sucrose compounds) inhibits on rate of crystal growth, depends
upon their composition and concentration.
In this connection, the following observations are focused:
 Potassium and sodium carbonates depressed the growth by 0.5% when
added at 3% concentration.
 rate crystallization decreases:
By chlorides and carbonates, amino acids and aconitic acids.
 Growth rate increases: Due to the availability of sulphates and glucose.
134

 About 0.05 – 1.5 % of raffinose reduces the crystallization rates and growth
rates by surface adsorption..
 Addition of small amount of manganous sulphate increased the growth rate
and altered the shape and color of sucrose crystals.
 When 0.5 g/100 g of solution concentration of gummy and materials decreases
the rate of crystallization up to 5.5%.
135

Molasses
 Molasses or black treacle viscous by-product of
the refining of sugarcane or sugar beets.
 Molasses varies by amount of sugar, method of
extraction, and age of plant.
 To make molasses, the juice is boiled to concentrate
it, promoting sugar crystallization.
136
it, promoting sugar crystallization.
The result of the first boiling is called "first syrup”,
and it has the highest sugar content.
 First syrup is referred as "cane syrup", as opposed
to molasses. "Second molasses" is created from a
second boiling and sugar extraction, and has a slight
bitter taste.

Molasses
 Nutritional value per 100 g
- Energy: 1,213kJ (290 kcal)
- Carbohydrates: 74.73 g
- Sugars: 74.72 g
- Dietary fiber: 0 g
- Fat: 1g
- Protein: 0 g
VitaminsVitamins
- Thiamine (B1) : 0.041 mg ( 4%)
- Riboflavin (B2): 0.002 mg (0%)
- Niacin (B3): 0.93 mg (6%)
- Panthothenic acid (B5) : 0.804 mg (16%)
Chlorine: 13.3mg (3%)
Minearls
- Calcium: 205 mg ; Iron: 4.72 mg Mg: 242 mg; Mn: 1.53 mg;
- Phosphorus: 31 mg; K – 1464 mg; Na – 37 mg; Zn – 0.29 mg
138

Types of Molasses
 Residual mother liquor from which little or no additional sugar can be
recovered. It is a by-product of the cane, beet, and dextrose industries.
 Molasses obtained from raw cane sugar production and cane sugar refining is
blackstrap molasses.
 Cane mill molasses: final molasses, and from reﬁnery - reﬁnery molasses.
 Beet molasses - molasses from beets, and that from starch hydrolysis is hydrol
molasses.
 Composition of molasses varies depending on location, varieties harvested, and
the efficiency of the operation.
139

Raw Sugar Production Processing Methods
140

Refining of Raw Sugar
 Sugar refining involves removal of impurities and decolorization.
The steps generally followed include affination (mingling and
centrifugation), melting, clarification, decolorization, evaporation,
crystallization, and finishing.
 Decolorization methods use granular activated carbon, powdered
activated carbon, ion exchange resins, and other materials.
141

• Sugar quality is the term applied to raw sugar to describe the chemical
composition of sugar & its fitness for the purchaser’s usage.
• The production of raw sugar is controlled to meet sugar quality
standards for constituent analyses such as polarization, moisture, ash,
Sugar refining
standards for constituent analyses such as polarization, moisture, ash,
colour, filterability, fine grain, starch, dextrin, and temperature.
• Sucrose is purified from raw sugar (97.5% sucrose) in different
processes such as:
142

 Affination is the first stage of processing of the raw sugar refining is
to soften and then remove the layer of mother liquor.
 Affination is dissolving off some surface impurities (molasses) from
raw sugar and is mixed with saturated syrup and then centrifuged to
extract the crystals.
Affination
 Mixture of raw sugar with high purity syrup (85%) called magma is
obtained.
 Melts outermost layer of the raw sugar crystal at 50ᴼC
 By centrifugation to remove resulting syrup from melting of the outer
layer.
143

Melting: The affinated sugar is dissolved with hot condensate to a liquid
approximately 72º Brix at 75ºC.
Purification: Remelt may contain some impurities and colorants must
remove by,
- Liming
1. Partial 2. Complete
- Carbonization- Carbonization
- Colorants remover by decolorization
Carbonation: Processing the liquor, aimed to removing the solids which
make the liquor turbid.
 It is achieved by adding milk of lime, [Ca (OH)2] to the
liquor and bubbling carbon dioxide through the mixture.
 Also it is the purpose to removing of further impurities that precipitate
from solution with calcium carbonate. 144

• Removes organic impurities such as the gums, amino acids and colour
from the sugar syrup.
• The carbonatation process is carried out in two stages to obtain an
optimum quality precipitate for filtration, i.e. a suitable size and
distribution of precipitate particles.
• This stage is controlled by the measurement of the pH of the solution
Cont….
• This stage is controlled by the measurement of the pH of the solution
which is important throughout the process and ensures complete
precipitation of the lime.
• Colour, gum and amino acid impurities precipitate out with the
calcium carbonate.
145

• The filter mud is subjected to water washing to remove residual
sucrose and this mud is a waste material.
Filtration
Char Filtration:
 Removing further impurities with activated carbon. Activated charcoal
is added to the syrup, removing color and inorganic ash.
 The relatively pure honey colored liquor obtained from the filtration
of "raw liquor" is subjected to final decolourization by contact with
bone charcoal.
 The bone charcoal consists of active carbon on a calcium phosphate
skeleton. It has a high surface area and the unique ability to absorb
color and inorganic ash impurities from the sugar.
146

Several techniques can be used for removing color. The main ones being:
• Activated carbon: Different types of activated carbon are available in the
market, place according to the precursor carbonaceous material (coal, wood,
coconut, etc.) and their size.
- The most common types used for sugar juice decolorization being powdered
activated carbon (usually termed as PAC) and granular activated carbon
Decolorization
(GAC).
• Polymeric media: Synthetic ion exchange resins or adsorbent resins are
used.
In addition to their chemical structure, polymeric adsorbents exhibit some
important porosity.
• Bone char: Pyrolyzed ground animal bones have a high surface area which
adsorbs color and remove some ash. 147

• Crystallisation is not only a means to convert the sucrose to a more
usable form, but also an important refining step, since pure sucrose
tends to crystallize out of the solution and leaving most of the
impurities in the associated syrup.
Crystallization
• The process is carried out under a reduced pressure of 75 - 90 kPa to
allow a reduced boiling temperature (60 - 700C), so avoiding the
further formation of color compounds.
148

Flow Chart for the Refining of Sugar
149

Basics of sugar technology

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