Sunday 12 June 2011

Sugar processing

SUGAR PROCESSING

  1. CANE HARVESTING AND TRANSPORT:

Cane cutting is done by contracted cane cutters. Extraneous matter levels is <3% and that the cane is cut at ground level with trash, roots, and soil removed

  1. WEIGHBRIDGE OPERATIONS

Transport weighbridge office

The weighbridges are equipped with sophisticated weighing devices e.g. load cells, so that precise measurements can be obtained. Weighing is important as it facilitates;

  • Payment to farmers and planters for the sugar produced from their cane.
  • It also helps in Statistical information regarding cane yields per hectare
  • Chemical control and determination of factory performance.

After weighing and offloading, a copy of the weighbridge ticket is given to the driver for the contractor, second to the farmers account, another to OGL, and the fourth to the harvesting and transport department.

  1. CANEYARD

The cane yard is the area that cane is offloaded while the gantry area is the area that cane is fed into the feed tables.

Cane off-loading equipments are;

  • Gantry cranes,
  • Hydro unloaders
  • Wheel loaders

Gantry Crane/ Overhead-Transporter Crane

The crane lifts a bundle of cane with the aid of a grab. The gantry crane operates in rectangle hence the crane can travel along or across the rails. The driver works in a cabin and operates levers for various motions of lifting and lowering of the hook the cranes transfer the cane from the stockpile to the feed-tables in case of inadequate supply during the day and at night when the trucks have stopped ferrying the cane to the factory

Hydro unloaders (Hilo)

The cane is loaded in packets or bundles bound by 3 chains or slings. One end of the slings is fixed on the top of the truck frame while the other end is fixed to a grooved pawl. The unloading crane consists of a vertical pin-jointed frame, pulleys and hydraulic systems. The unloader works behind a wall of about 2.5 m high. The storage yard requires a concrete floor on which a front-end loader works.

Wheel loaders

The wheel unloaders are mobile engines fitted with grabs they resemble a tractor but with grabs at the front for grabbing the cane or simply pushing it in to a pile. They offload in the gantry area.

Feed tables, kickers and Auxiliary cane carrier

Feed tables

This is a short, wide cane carrier with chain and slats conveyor enclosed by short sidewalls. The crane deposits the cane on the feed table and keeps up the supply to it as it discharges an operator who regulates the speed of the lateral feed carrier controls the amount of cane delivered to the main carrier. At the end of the table, it's equipped with a 'kicker' or 'tumbler', which consists of a shaft fitted with arms arranged in a helix along its length. The object of the kicker, whose direction of rotation is opposite to that of the carrier is to ensure that regular and uniform quantities of cane are delivered to the main carrier. The amount of cane fed in to the carrier should be uniform. If too much cane is fed in the carrier it will choke the knives resulting in stoppage. If feeding is less the capacity of the knives will be underutilized hence low efficiency and also reduction in set targets for extraction.


Auxiliary Carrier

The carrier runs at right angles to the 4 feed tables that supply it with cane. It has three portions; horizontal, inclined and the head portions.

  1. CANE PREPARATION

Cane preparation is the process that cane undergoes before entry into the diffuser. This is achieved by use of two set of knives and a hammer:

Leveler Knives

These set of knives are placed just before the end of the inclination. They even out the layers of the cane while cutting it. They are arranged to work in a high clearance and the consequence leave a large preparation of uncut cane. The rotation of the knives is in the same direction as the feed. The cutting edge is hard face to decrease wear; it consists of a set of 44 hard-faced knives. The leveler is driven by a steam turbine at a speed of about 650 rpm. Towards the end of the carrier is a feed drum, it's driven by an electric motor and it ensures uniform feeding towards the heavy-duty knives.

Heavy duty knives

The heavy-duty knives are also hard faced to reduce the rate of ware. It consists of a set of 60 knives. The clearance is smaller to facilitate further disintegration. The knives rotates counter to the flow of cane. A steam turbine is also used in this case to drive the set at about 650 rpm. This set of knives gives a cane preparation index of 75%. The cane drops, through a chute, to a conveyor-belt which carriers the cane to the shredder for final preparation. In between the shredder and the knives is a tramp iron magnet, which arrests any metallic object, especially the broken or fallen knives, before reaching the shredder.

Shredder Hammers

The shredder has 245 hammers. The shredder is provided with more anvil bars than the heavy-duty knives and a smaller clearance. The shredder rotates at 1200rpm to open up the cane-cells to a final preparation index of 92%.

The prepared cane is then weighed automatically by a belt-weigh to give the real time crashing rate.

  1. DIFFUSSER AND DEWATERING MILLS

It consists of a long tank enclosing a horizontal conveyor on which the prepared cane is placed as a layer of uniform thickness. Its body comprises 12 extraction stages and a draft juice stage. Sucrose in sugar cane stalk is present in enclosed cells. The extraction process in the diffuser combines imbibitions, lixiviation and diffusion these processes involve rupture of the cells, and washing of the broken cells by the water or juice in contact with them. Imbibition is the spraying of hot water to the shredded cane to help extract the juice. Lixiviation involves spraying dilute juice onto the shredded cane to help in extraction while Diffusion involves the movement of sugar molecules from regions of high concentration to regions of low concentration. The integration of these three processes ensures increased levels of extraction (95%) as compared to the extraction using mills that had extraction levels of about 70%

Imbibitions water at 800C at set amount is introduced at stage 11 of the diffuser where it percolates through the mobile cane bed washing out and allowing cane sucrose to diffuse into it. The juice then percolates through the perforated screen on the floor of the diffuser into the tray below it. Re-circulation pumps lift the thin juice in the trays and spray it on the mobile cane in such a way that the juice has enough time to percolate to the previous stage tray. High juice flow rate promotes extraction although excessive high flow rate will cause flooding. Juice sprayers are designed to set automatically in order to keep the liquid level just below the cane bed. The Re-circulation pumps at stage 2 and 1 pass the juice through two scalding juice heaters 2 and 1 respectively, and onto the fresh cane as it enter the diffuser. The scalding juice heaters raise the temperature of the juice to 850C this helps to saturate the cane with juice as early as possible and to wash high brix juice off the entering cane. The juice outlet temperature from the heaters is automatically controlled by the amount of vapour 1 into the heaters. In effect, the scalding stage increases extraction. The scalding juice percolates through the fresh cane, washing most of the sugar down to the draft juice tray. The draft juice is pumped to the process house via a pneumatic valve that adjusts the flow rate according to the level of the mixed-juice tank

Milk of lime is dosed into the thin juice in the diffuser at stages 2 and 7 to raise the pH to 6.5-7.0. An automated pH sensor is used to monitor the pH and regulate the dosing of milk of lime by 2 peristaltic pumps with a VSD. Vapour 2 from the process house is injected into the juice trays 4, 5, 6,9,10 and 11 to maintain the temperature of the thin juice at 800C. An automated temperature detector regulates the V2 injection to avoid overheating. Two sets of 9 lifting screws are used to disturb the cane bed at stages 2 and 9 to enhance percolation of the thin juice. Shear pins allow the whole screw to swing out of the bed if excessive load is applied due to a stopped screw drive. Then cane bed is maintained at an optimum height of 1.5m by balancing the diffuser chain speed and feed rate. Bed level sensors and transmitters are installed at stage 2, which relay the information to the controls monitor. Sight glasses are also available along the diffuser.

Other materials into the diffuser include: mud from the clarifiers that is pumped at stage 3, press water from the drying mills sprayed at stage 9, and chain wash and sump pit water that is sprayed on stage 11. Primary drying of cane is done at the exit of the diffuser by a press drum, which forcefully rolls on the cane bed as it exits the diffuser reducing the moisture by 20%. This water percolates to stage 12 for re-circulation. A 3m diameter kicker rotating at 25 rpm loosens the cane bed after compression by the press drum. The cane fibre (now referred to as megasse) drops from the diffuser onto a slat conveyor (C140), which conveys it to the drying mills for further moisture reduction.

Other Diffuser Target parameters

  1. Throughput (Tonnage)         330 – 370 Tones/hour
  2. Imbibitions water on fiber        350% OR 200 – 228 Tones/hour
  3. Poll extraction             > 94.5%
  4. Press water brix            < 2ยบ Brix
  5. Draft Juice rate (rate pumped to MJT) 400 – 500 Tones/hour

DEWATERING MILLS

These are roller mills that squeeze the megasse leaving the diffuser. Hence maximizes extraction.

A series of two rubber conveyors (C141A & C141B) carries the hot megasse to the first set of drying mills. C141A has a magnet to arrest any tramp iron before the mills Imbibitions water is added to the bagasse from the first mills, which is then conveyed to the second set of drying mills by a chain & slats conveyor, C149. The megasse is squeezed again and then released onto conveyor C154A as the final bagasse. A second rubber-belt conveyor (C154B) picks the bagasse to direct it to the bagasse conveyor system.

Megasse is fed into the mills via a Donnelley chute into a gap between the force feed roller and the top roller. The megasse is squeezed in between the top and the feed roller and finally between the top and the discharge roller as shown in the diagram below. The pressed juice collects in the mill beds and is directed by a trough into a tank, then pumped to the diffuser. Scrappers are installed to clean the discharge and the top rollers off any bagasse in the grooves. The teeth of the rollers have weld deposits that enable firm gripping of the bagasse hence maximum extraction of the juice. Arcing of rollers flanks maintains a rough cast on the grooves worn out due to friction.

The factors that contribute to low bagasse moistures from the dewatering mills include

  • Mill speed
  • Bagasse Blanket
  • Hydraulic Pressure
  • Mill torque    


 

FEED WATER;

TYPES OF FEED WATER

CONDENSATE

This is got from process house. It is the most ideal for boilers. It consist 80% of the feed water. It's free from cat ions and it's at the right temperature.

SOFTENED WATER;

This is make-up water used to add into condensate. Softening involves the exchange of Magnesium and Calcium ions with sodium ions. Softening is done at the water treatment plant. The water is at ambient temperature thus not very ideal for boiler use. It requires a lot of energy to be converted into steam. It constitutes less than 20% of the boiler feed water.

RAW/CLARIFIED WATER

Used as make-up only when condensate and soft water system fails.

It's mainly avoided at all costs because the water has hardness which leads to scaling of the boiler tubes.

  1. PROCESS HOUSE

The juice that has been extracted from the mills pumped to the process house. This section involves;

  • juice treatment
  • sugar pan boiling
  • sugar separation
  • Sugar drying.
  1. JUICE TREATMENT

It involves the following juice weighing, juice clarification, juice evaporation, syrup sulphitation

JUICE WEIGHING

The juice is first of all weighed. The reason for weighing is to control juice flow, measure efficiency of the extraction and also for accountability purposes

Weighing is done utilizing three load cells mounted on the weigh tank; the stress on the load-cells is converted into an electric signal and sent to an output indicator in the electronic control box, where it is converted into a weight reading.

JUICE CLARIFICATION

Mixed juice from the extraction plant consist of 80-84 % water, suspended particles of sand, fine bagasse cane wax and air bubbles, and total dissolved substances (sucrose, salts inorganic acids etc). The object of clarification is to purify and correct the pH of the juice. The following processes are done

LIMING:

It is done by use of hydrated or slaked quicklime. The dosing pumps have inverters which help to maintain the ph of the limed juice at 7.2. Milk of lime preparation consist of two tanks with stirrers, one of the tanks is for preparation and the other one for dosing. In case of failure of the dosing pumps, milk of lime can be dosed directly from preparation tank by use of transfer pump. However it's not recommended since it's hard to control amount of mol dosed. Liming is of great merit as it raises pH thus prevents sucrose inversion

JUICE HEATING


Primary heating: Juice from weighed juice tank is pumped by first stage pumps to the primary heaters. It's by use of vertical shell and tube heaters. The main duty is to heat juice from 650c to 850c. It uses vapors 2 as the heating media.

Secondary heating: Juice from primary heaters is pumped by second stage pumps to the secondary heaters aims at heating the juice from 850c to 1030c. The heaters use vapour 1 or exhaust as the heating media.
Heating of the juice helps to speed up chemical reactions in the clarifier, has sterilization effect and also helps in flashing

JUICE FLASHING:

Aims at freeing the juice of all the entrapped air. In the pipes the juice is under pressure, and high temperature usually 30c superheat. When it gets into the flash tank which is open on top, some pressure is lost and energy released in terms of vapour. This lowers the juice temperature. The merit of this process is that air bubbles are removed. If they find their way into the clarifier, air bubbles cause the floc to float instead of settling. It also ensures uniform temperature of juice getting to the clarifier reducing turbulence in clarifiers.

DISTRIBUTION TANK:

It divides the juice between the two sets of the clarifier. It also acts as a buffer introducing juice into the SRI clarifier without turbulence. Dosing of flocculants starts at this point.

DOSING OF FLOCCULANTS:

Flocculants are polymers of high molecular weight, added to lime juice before entry into the clarifier to enhance the production of large flocs in the mud.

The addition of flocculants to water when preparing a solution is done at a slow and uniform rate to avoid formation of lumps. Water used for preparation of solution should be of good quality and at a temperature of less than 500c. Too high temperature will denature the polymer.

CLARIFIERS

It is designed such that juice inlet does not disturb the settling of mud. Juice takes 30-45 minutes to clarify. It has uniform distribution of juice. Turbulence is highly minimized. below the clarifiers are the clear juice tanks: there main purpose includes: Acting as a baffle allowing to take fluctuations in flow also In case of short breakdown downstream equipment can be worked on without stopping the whole process. They are also used for liquidation during maintenance. At the clarifier, the major chemical reaction is that of the Ca++ anion with the phosphate radical to precipitate Ca3 (PO4)2.Some inorganic cat ions, e.g. PO4, SiO2, and SO3 are partly precipitated by the increase in Ca2+ ion. Formation of floc is based on Ca3(P04)2 and protein.

The mud is separated using the dorco pumps is recirculated to diffuser while the clear juice obtained is pumped to be evaporated via pre evaporators

Evaporation

The purpose of evaporation is to concentrate the juice by removal of the water through heat with a target brix of 65%. The clear juice is divided into three streams, A, B, and C. A and B goes to the pre – heaters, then kestner evaporators then A and B evaporators. The C- stream is pre – heated and taken direct to the C – evaporators.

CLEAR JUICE PREHEATERS:

The aim is to raise the temperature of the juice to about 110-1150c.

This ensures rapid evaporation when the material gets into the Kestner. The heaters uses exhaust as the heating medium.

KESTNER:

It is a once-through evaporator (rising film) which aids in production of vapour 1 for use in the diffuser and pan floor. It has much larger heating surface, higher juice velocities and hence less scaling, less Retention time, less sucrose inversion or colour forming and better heat transfer...

It has a separator where separation of juice and vapour takes place.

Heat transmission in an Evaporator:

A sugar evaporator consists essentially of a tubular calandria serving as the heat exchanger. The heating steam surrounds the outside of the tubes and the juice to be evaporated circulates inside the tubes.

In the multiple-effect evaporation, the juice enters the first evaporator and is heated by exhaust steam. The steam loses the heat to the juice, which loses water in vapor form leaving a more concentrated juice. The exhaust steam condenses and the condensate collects in a tank placed below the vessel. The vapor produced is passed to the second evaporator, which is under vacuum. This vacuum creates the necessary temperature difference in order to utilize the vapor arising from the first vessel to heat the juice in the second vessel, the vapor produced by the second to heat the third and so on. The vapor after the fourth effect is simultaneously and continuously injected with pressurized cold water in a condenser. The cold-water jets in the condenser are designed such that the vapor condenses and is extracted together with air and hence creating a vacuum in the fourth evaporator.

The measure of the vacuum is also a function of the position of the condenser relative to the evaporators. The vacuum in the fourth vessel induces a higher rate of heat exchange in the third evaporator, inducing a less vacuum in the third vessel. A vacuum is induced in the whole stream although the vacuum decreases, sequentially, from the fourth to the first evaporator.

Boiling under vacuum presents two great advantages, in that it increases the total difference in temperature between the steam and the juice by a quantity equal to the drop in the boiling point of the juice between the pressure of the first and that of the last vessel. It also permits evaporation to be carried out at temperatures proportionately less dangerous, from the point of view of inversion and of coloration of the juice, as the juice becomes more concentrated and more viscous.

RAW SYRUP TANKS:

They act as a baffle for material leaving the fourth effect they include the syrup extraction tank and the syrup boxes. Syrup tanks are situated on the ground in order to enable extraction by gravity. They are provided with flash lines to ensure that any vapour on the syrup does not find its way to the pumps and sulphitation tower.

SYRUP SULPHITATION:

This aims at improving on the colour of the final sugar. Sulphur dioxide gas is injected into the syrupthis step is however avoided when processing brown sugar.

Sulphur in powder form is burnt in the stoves at a temperature of 3500c.This is maintained by constant cooling of the stoves by use of water. It is important that the furnace be cooled. This protects the furnace metal from fast corrosion, which would result if left to go red-hot. De- ashing is done frequently to ensure that sulphur burns well. Air of combustion is passed over quick lime, which has great affinity for water thus absorbs moisture from air. The quick lime need renewal once in 8 hrs before saturation. In the presence of water combustion air, sulphur burns to give sulphuric anhydride SO3 instead of sulphurous anhydride SO2. Further reaction with water forms sulphuric acid. Complete combustion of sulphur requires 12 – 16 % excess air

Burning produces sulphur dioxide which passes through a scrapper to remove any solid impurities which includes unburnt sulphur. Sulphur dioxide is passed through a cooling column to ensure a temperature of 4000c hence preventing decomposition.

Sulphitation tower:

Sulphur dioxide sanction is created by syrup injection pumps which create a sanction in the eductor. Syrup mixes with the gas and adsorption takes place. The free fall of syrup also ensures mixing. Sulphur dioxide binds colour forming compounds which later settles as scam. It also reduces ferrite salts in juice into colorless compounds.

  1. SUGAR PAN BOILING

There are two types of pans, namely batch and continuous pan.

A batch pan is a vertical cylindrical vessel consisting of a calandria and a vapour space. During boiling a set of seed is introduced and syrup or molasses is fed until the pan is full. Once the boiling cycle is completed, the product (massecuite) is discharged and another boiling cycle is started. The basic features of a batch pan are as those of an evaporator. On the other hand ,a continuous pan is horizontal vessel with a number of compartments or cells (usually 12) connected in series. The seed is continuously fed to the first compartment and flows through each compartment until it reaches the last compartment. Molasses is fed to each compartment and the product (massecuite) is continuously withdrawn from the last compartment.

The following parameters are maintained to ensure appropriate crystal growth:

The concentration for the syrup to the vacuum boilers is 60-70 brix.

All the strikes are boiled tight from the beginning also all massecuite are boiled free from false grains needle grains and conglomerates

Pan boiling time and required crystal sizes are as follows

  • 'A' strikes 1.5 – 2.0 hours crystal size 1.00mm
  • 'B' strikes 2.5 – 3.0 hours crystal size 0.5-0.7mm
  • 'C' strikes 4.0 – 6.0 hours crystal size 0.25-0.40mm

Massecuite receivers are maintained at 60% or below before running any of the curing stations A, B and C

  1. Sugar Separation and Drying

When a strike is ready, the massecuite is dropped into a strike receiver. The receiver is fitted with an agitator to maintain the mass in a slow and continuous motion. Further crystallisation can be achieved by cooling the massecuite in order to raise the super-saturation of the mother liquor. Therefore, low purity C massecuite is pumped to a vertical crystallizer where further crystallisation takes place thus improving exhaustion. The crystalliser is equipped with cold-water coils and an agitator rotating at 0.25 rpm. Retention time is about 30-40 hrs with the rate of cooling being 1oC / hr.

The massecuite is than reheated before being fed into the C-Centrifugals. The heater is a closed vessel containing several bank of finned steel tubes stucked together over which massecuite flows. Hot water is circulated inside the tubes, heat being supplied by a separate tubular heat exchanger using exhaust steam as the heating medium. The flow of massecuite and water are counter current; the massecuite flows by gravity while the water is pumped through the heater tubes in a closed circuit.


 

CENTRIFUGALS

A centrifugal is used for separating sugar crystals from a massecuite. A centrifugal machine consists of a spindle with a perforated steel basket connected to it. The spindle and the basket are driven by an electric motor and rotated inside housing. A screen is inserted into the inside of the basket, alongside its inner circumference. This screen keeps back the crystals but the mother liquor is allowed to pass through holes or slots and flows down the housing walls.

There are two types of centrifugals

Batch (A) Centrifugals

The batch fugals are used for separating A-sugar from A-massecuite.

The massecuite is charged from the top and builds up against the screen until a wall of massecuite of a certain thickness is formed. The centrifugal rotates rather slowly at this stage; to allow the massecuite to spread evenly over the surface of the screen, thus preventing imbalance.

When the basket is loaded with massecuite, the machine accelerates to high speed (1000 rpm) and the molasses will be separated, water sprayed on the inside of the sugar wall to wash the molasses residue from the crystals. Spinning continues for a while to remove as much of the wash-water as possible. The basket is then slowed down, the discharge valve opens and sugar is removed by a plough, which is lowered into the basket. The discharge valve closes and the cycle is repeated.

Continuous Fugals

The continuous fugals are for the B and C sugar, massecuite is continuously fed into the fugal and sugar and molasses continuously extracted. The high force with which the crystals contact the wall causes damage to the crystals. Thus, continuous fugals are not used for A-sugar.

SUGAR DRYING

Sugar discharged from the A-centrifugals is wet and hot and has to be dried before storage and packing. The sugar is dried to reduce microbial activity and to prevent caking. A bucket elevator transports the sugar from the conveyor up to the sugar drier.

A sugar drier consists of a drum through which the sugar passes in counter current with hot air. The drum is slightly inclined to discharge and it's supported by rollers. The inside of the drum is provided with longitudinal louvers, which pick up the sugar and drop it as a curtain across the full diameter of the drum. The hot air drawn through the drum provides enough heat to evaporate off the water Air from the atmosphere is heated by passing it through tubes of a heat exchanger with steam as a heating medium. The air is heated to about 65oC and drawn by a fan through the drum passing a wet dust catcher to remove the dust particles.

A cyclone is also fitted this is charged with sucking sugar dust via a fan and employing a mechanism which sprays water to dissolve the sugar dust. The dissolved sugar is then pumped back to the mixed juice tank.

Vibrating Screen

Dried sugars exiting from the dryer passes through the vibrating screen. The sugar that passes through is conveyed for bagging or packaging. Lumps collected are dissolved in water and pumped to the mixed juice tank.

  1. SUGAR HANDLING AND PACKAGING

Sugar handling involves branding and bagging of sugar, storage and its subsequent marketing

Sugar packaging is a step in the larger aspect of processing. Sugar from the vibrating screens passes through belt conveyors. On the bridge conveyor is an electromagnet that traps any metal pieces at the junction of transfer conveyors for A and B bins is a deflector door that is used to control the flow of sugar to the sets of bins depending on demand. The Sugar bins are vessels/containers which hold sugar temporarily in order to create a good head when feeding into the packaging machines. For white sugar, the bins should be operated above ¼ full to ensure uniform feeding into the cups. For brown sugar, bins should be maintained at ¼. Too high level will lead to caking of sugar. Too low level will lead to non-uniform flow into the cups. Before packaging commence a sample is taken from the bridge conveyor and analyzed the parameters required include:

  • Colour             (white < 550 ICUMSA, and brown > 550 - <1500 ICUMSA)
  • Moisture content     (<0.1%)
  • Pol            (white > 99.7 and brown > 99.5)
  • Insolubles         (<150mg/kg)

Sugar is packaged in 250gm, 500gms, 1kg, and 2kg brands for both brown and white depending on market demand.

Packaging machines:

They are eleven in number. They are forming, filling and sealing type of machines.

For machine number 1- 5 packaging is done by use of auto baler. While For machine number 6-11 packaging is done manually and weight checked by use of a mass balance. In the auto-baler system, the packet is first compressed to remove and entrapped air during filling. A baler bag is fed into the machine which fills it with the right number of packets depending on brand. This is achieved by a set of instruments which controls the filling and sealing of the bale. The sealed bale passes through a scale check which rejects over weights and under weights.

A well sealed packet has the following qualities:

Nutritional information:

  • Company logo
  • Branded sugar marketing logo
  • Date of manufacture
  • Time of manufacture
  • Machine number
  • Date of expiry: 3 years from date of manufacture
  • Colour shade should be as specified by quality assurance department

Stacking:

Bales are staked on pallets awaiting transfer to the marketing store

(35 bales per pallet) done by use of Folk lift any sugar transferred to marketing store is recorded and the shift performance computed

Sugar bagging;

Involves packing of sugar in 50kgs bags

Sugar from B- bins is directed to auto scales which control bag filling. By placing the empty clean bag below the auto scale opening and tripping the door, an approximately 50kg sugar is released into the bag. Scale checking is done by an electronic scale that on which the bag sits. Any extra-weight is collected by scooping sugar from the bag. Under weights are corrected by adding sugar manually into the bag.

The bag is sewn using an electric powered sewing machine. The sewed bag is carried to the marketing warehouse through a series of rubber conveyor. The 50Kg bags should be serialized have date and time of manufacture.

For accountability purposes all branding machines and scales are zeroed at the start of shift and production per hour recorded Stock taking of bags, films, baler bags, and other items used is done at the close and start of a shift all the damages are accounted for at the close of shift

Sugar for remelting (sweepings) is weighed before remelting


 

Sausage processing

SAUSAGE PRODUCTION

CHOPPING

Here the ingredients for every type of fresh sausage, continental product or other products are mixed in the required proportions.


Major raw materials common to most products;

  • Lean pork
  • Lean beef
  • Back fat
  • Semi lean
  • Semi lean emulsion
  • Rinds
  • Off cuts
  • Sausage Rusk
  • Peatex
  • Cornstarch
  • Maize meal
  • Soya gel
  • Salt mix; constitutes ascorbic acid, sodium try polyphosphate, sodium nitrite sodium chloride, sodium metabisulphite and dextrose. It is used for fresh sausages.
  • Curing salt; constitutes of ascorbic acid, sodium chloride, and dextrose. It is used for continentals.

Examples;

  1. Meatloaf requires lean pork, lean beef, back fat, bacon pieces, semi lean salt mix and ice.
  2. Beef sausage requires lean pork, lean beef, back fat, semi lean emulsion / semi lean, Rusk, Peatex, cornstarch, salt mix and ice.

Materials that require mincing are minced at different screen diameters depending on the product to be made.

Ingredients are weighed each at a time then put into a chopping machine, which chops and evenly mixes the ingredients.

The chopped sausage, continentals or other products mass is emptied into a meat van. Chopped masses are for products such as fresh sausages, continentals (for cooked products) hamburgers, burgers, frankfurters, and viennas among others.

STUFFING

Chopped mass from chopping area is fed into stuffing machines where every machine is particular to a certain type of product e.g. burgers, sausages or boerwors.

Mass for fresh sausages is packed into use collagen casings of different diameters e.g.23mm, 29mm or 28mm and hence the various types of fresh sausages. After stuffing sausages are packed in pouches to weigh either 500g, 400g 200g or 1kg.

A jet printer prints the respective day's production code on every pouch as they move on a conveyor belt.

They are passed through a metal detector and if okay they are delivered for sales or chilled /blast frozen awaiting sales.

Burgers and boerwors weigh either 500g or 1kg.

Beef processing

BEEF BUTCHERY.

Beef are classified as;

  • High grade beef for sales; this has well marbling fat
  • Commercial grade for minced meat, staff meat and sausage processing
  • Fairly average quality.

Beef, lamb and goats are delivered by refrigerated trucks and offloaded at beef receiving area. The quarters are hoisted on a monorail, weighed, and sprayed with 50 ppm chlorine water to reduce the microbial load and are stored overnight in a chiller operating at between -2°C to +2°C. The same is done on lamb and goat carcasses.

Butchery

In the butchery, qualified butchers cut up the quarters from the chillers to obtain the various beef prime cuts. This is also done to goat and lamb carcasses.

Beef prime cuts

These cuts include: top sides, rump steaks, ossubucos, silver sides, and eyepieces, from hindquarters. Sirloins, strip loins, fillets, briskets and shins from the fore quarters. The cuts are trimmed for better presentation and appearance. The cuts are then packed, weighed, labelled and sold or chilled or blast frozen awaiting sales.

Other products from butchery are bones and off cuts. Commercial grade beef are just deboned and the steaks used for sausage and minced beef processing.

contd

PORK BUTCHERY

Carcasses under chilled storage after slaughter are butchered and it's from this here that pork prime cuts are obtained.

Breaking stage

Carcasses are removed from the chillers, weighed and then moved to the breaking stage of the butchery. Here each carcass halves are cut each into three parts namely: pork shoulder, pork middle and pork leg. Before breaking pork shank/knuckles and fillets are separated from each half.

Each of the three parts is distributed to butchery tables where butchers cut up the parts to obtain the various prime cuts.

Pork leg

From leg comes black forest ham, leg steaks, gammon ham, boneless rind-on rolled, flesh meat, rump steak.

Middles

From middles pork boneless loin rind on/off, kassler, streaky bacon, belly bacon, belly spare ribs, baby spare ribs.

Pork shoulder

From the shoulder come collar bacon, rind less bacon, neck fillet bone in, shoulder spare ribs, shoulder chops and pork shank.

Packing

The prime cuts are then packed, weighed labeled and vacuum-sealed and sold or blast frozen awaiting sales.

Other products from the section are semi lean, back fat and off cuts for sausage processing.

Fat

The fat got from pork has several uses i.e. the back fat goes to sausages making, the soft fat also goes to sausages processing. Celestine is used to manufacture pure lard. While flare fat and cooking fat goes to sausages making.

Quality assurance personnel monitor aspects such as hygiene inside butchery, meat temperature, and examination of meat for foreign objects, how meat is cut up and floor temperatures, which should be, less than 18oC and packaged product presentation.

Processing of hogs


SLAUGHTER HOUSE OPERATIONS

Pigs are driven to the stunning box inside the slaughterhouse where they are stunned at a voltage of 180v one at a time.  They are stunned below the ears i.e. shortest distance to the brain. Stunning immobilizes the pig, for easy exsanguinations. The stunned pigs are hoisted on a monorail with the head facing down.
Sticking
Piercing the heart and arteries using a sharp knife does sticking. These aims at draining all the blood from the stunned pig thus improve the meats keeping quality
Bleeding area
The carcass is moved to a bleeding area where pumping of the heart and gravitational force aid in draining the blood out of the carcass.
The method employed is Vat scalding. Water is heated thorough steam injection into a vat able to hold 3 carcasses at ago.
 The carcasses are railed into the scalding tank, where water is at between 65-70oC to soften the hairs for de-hairing.
Dehairing
A de-hairer machine removes the body hairs of the carcass.
Summary
Summary work on the carcasses begins after de-hairing at a hoisting table where the carcass is hoisted with the head facing down and hind legs claws are removed. Fore legs claws are then removed and then a knife is used to remove residual hair on both the fore and hind sides.
Singeing
 The carcass is then moved to a singeing area where a gas flame is used to burn out the residual hairs on the carcass body.
 The carcasses are sprayed with treated water after this the tongue is exposed for inspection purposes.

Evisceration
Evisceration is then done where viscera are removed and then the carcass is split along using a splitting saw into two halves i.e. left and right halves
Washing and chlorination
 The carcasses are sprayed with clean treated water and then with chlorine water. This reduces the microbial load on the carcasses’ skin.
 The carcasses are then railed to an inspection area where a meat inspector inspects the meat to accept or condemn. A carcass is condemned if any signs of infection are observed.
After inspection the carcasses are then weighed to record the live weight. The fat depth is also determined.
 The pork meat is graded according to the distribution of fat and the proportion of lean to fat meat. It is graded as from one to five.  The head is cut off and separated from the carcass
 The carcasses are then stored in chillers operating at between  -2 and+2oC. This allows for rigor mortise to take place and also allows for the aging of the meat and these principles contribute to meat tenderness and improve the meat flavor.
The offals are taken to pet foods processing including the liver and the spleen while the pork heart is packed for export. High levels of hygiene are observed and there are foot pedal warm water taps and soap for hand washing and sanitized footbaths at the entrances to the slaughterhouse.