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DEPARTMENT OF CHEMICAL AND PROCESS ENGINEERINGSCHOOL OF ENGINEERINGMOI UNIVERSITYPLANT DESIGN FOR THE PRODUCTION OF POTATO PUREE, CHIPS AND EXTRACTION OF POTATO STARCHBy: MUTUA EDWINCPE/17/08LIMO KIPTALAMCPE/12/08AKAKA EVANS CPE/1005/08

Supervisor: DR.S NAMANGO1ST FEBRUARY 2013OBJECTIVEDesign a plant for potato starch, puree and chips production.

INTRODUCTIONPotato is an edible starchy tuber produced by certain plants of a genus Solanum of the Solanaceae family, especially the common white potato.Potato is a staple food in most countries being an annual herb and varies from brownish-white to purple.Potatoes require cold storage which prevents sprouting.

INTRESTED POTATO PRODUCTSStarch Its a carbohydrate consisting of a large number of glucose units joined. Its basically produced by all green plants as an energy storage.Its a white, tasteless and odourless powder that is insoluble in cold water or alcohol. PureePuree is basically a paste or thick liquid suspension made from cooked potato.Puree and dehydrated forms processed from potatoes are the main ingredients for making liquid and semi solid products such as beverages, soup, baby food, ice cream, baked products and various snacks.Chips- its a thin slice of potato that is deep fried or baked until crunchy. Potato chips are commonly served as an appetizer or snacks. Basically chips are cooked and salted having various flavourings and ingredients. JUSTIFICATIONPotato crop takes an average of 4 months to mature compared to other crops e.g. maize, wheat which takes an average of 10 months.Cereals especially maize is used for food security in Kenya hence its use for starch production interferes with government food security policies.

LITERATURE REVIEWPRODUCTION OF POTATO PRODUCTSStarch extraction: Basically this is a method of getting starch a carbohydrate from starch containing plants e.g potatoChips production: This entails the chipping of potato and precooking for consumption normally referred as frozen chips. Puree production: This entails mashing of potatoes basically for consumption.This potato products make the essence of creating the company in Kenya having the possibility of starting a potato company which will utilise the gap experienced faced now.PROCESS DESCRIPTIONStarch extractionThe techniques involved in starch extraction include:-Cleaning-Rasping-Extraction & Fruit water separation-Dewatering & Drying

The potatoes are cleaned to remove soil and stones through washing machine where the potato are spinned around.The purified potatoes are mashed by a rotary saw blade resulting in complete disruption of the potato cells releasing the starch. The machine eliminates skin fragments which lead to poor starch quality.Separation is done by conical rotating sieves. For better starch isolation water is applied to the sieves through nozzles. While starch and fruit water passes through, the fibres are retarded by the sieves. the fruit water is separated in several steps by means of hydro-cyclone.The refined starch milk has a dry matter content of about 35 % to 40 %. The starch is dewatered by rotary vacuum filtration to moisture contents below 40 %.Drying is conducted by means of a flash dryer. Starch must not exceed 15 % of residual moisture to be suitable for storage.

2. Chips productionThe techniques involved in chips production include:- Washing- Peeling CuttingWashing and dryingBlanchingPar fryingDryingCooling and freezingWashing is done using high-pressure spray washers; water at 250 psi is directly sprayed at the surface of potatoes as they tumble over rotating brushes. Peeling is done by use of high pressure steam where losses are between 10-15% and depend on the efficiency of the equipment.Tubers are cut lengthwise to obtain maximum long sticks with minimum loss. Strips shorter than 30 mm are removed and taken to the starch extraction section.Materials that come out of cut potato cells cause the products to stick together and to cook unevenly. They are removed by washing and dried using mechanical de-watering.Hot water blanching at 65oc-100oc destroys enzyme activity and leaches out, reducing sugars and other chemical constituents that cause off-colour and off flavour. Evaporation of water from cut surfaces before deep-frying gives chips their characteristic crispy exterior. The pre-cooked chips are dried using cold air at 20oc. The product is cooled and deep-frozen at -18 to -20C in order to retain texture and avoid damage as a result of ice crystal formation. 3. PureeThe techniques involved in puree production include:WashingPeeling and rewashingCuttingPureeing processCanning and freezing

Its produced by steam cooking of the peeled potato roots and passing the cooked materials through a pulp finisher. The material are blanched at 65 to 75C. the blanched materials into puree is carried out at this point using the hammer mill. The blanched puree is pumped into a surge tank and held at 65 - 75C for further starch hydrolysis. Raw potato mash can be added at this stage to increase starch conversion. After starch conversion, the temperature is raised to 100 - 110C in a heat exchanger to inactivate the enzymes, and a final grinding step will be carried out with the use of a pulp finisher to obtain the smooth puree.The finish-cooked puree is packaged in plastic containers for refrigerated or frozen storage. pH adjustment of potato puree to 1.5, 4.5 and 11.5 prior to filling in jars followed by pasteurizing at 90C could prolong the shelf-life of the product up to 9 months at room temperature.

APPLICATION OF STARCHStarch may be used as food; Ingredient in making medicines.It is used as food thickener in soups.Carefully selected starches help make yogurts. Starch as raw material in industrial productsAs filler in papermaking.Preparing laundry starch MASS BALANCEThe conservation equation is as follows:Accumulation = Material in + Generation - Consumption Material outThe mass balance was carried out in each equipment.AssumptionsTargeted counties: Nakuru, Baringo, Uasin Gishu and BometApproximately annual production is 200 MT according to Kenya Agricultural Institute.

-Service sector consumption-60% -Domestic consumption-30% -Remaining-10% Assume 300 working daysBasis calculations:0.1 x 200=20MT

MASS BALANCE AROUND THE RASPING UNITAssumptionsSkin fragments = 0.5% weight. 30% of potato is used for starch extraction.70% of potato is used for chips and puree.10% of water remains with the skin.

MASS BALANCE AROUND FLASH DRYERAssumptions:90% efficiency.Proteins and starch do not evaporate.

ENERGY BALNCEconservation of energy equation: Accumulation = Energy in - Energy out + Generation - Consumption AssumptionsA reference temperature of 20is used in the analysisSpecific heat capacity of water do not vary with temperature C pwater = 4.187 KJ/Kg.CSpecific heat capacity of potato vary with moisture content and is given by the following formulaC p potato = 0.0335 X %M.C + 0.8374

ENERGY BALANCE AROUND ROTARY DRYERAssumption: no starch is vaporized.Negligible energy loss.CP cld air = 1.25 Kj/kgCP moist air = CP waterComponentInput (Kj/hr)Output (Kj/hr) Semidried starch490600Dried starch055750Moist air067486.64Hot air 74176.640Total123236.64123236.64ENERGY BALANCE AROUND THE DRYER

ComponentInput (Kj/hr)Output (Kj/hr) Feed( chips & water)182011.70Product(chips & water)031058.6Cold air500000warm air 056250Total232011.7123236.6427THANK YOU