Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23N—MACHINES OR APPARATUS FOR TREATING HARVESTED FRUIT, VEGETABLES OR FLOWER BULBS IN BULK, NOT OTHERWISE PROVIDED FOR; PEELING VEGETABLES OR FRUIT IN BULK; APPARATUS FOR PREPARING ANIMAL FEEDING- STUFFS
  • A23N7/00—Peeling vegetables or fruit
  • A23N7/02—Peeling potatoes, apples or similarly shaped vegetables or fruit

Definitions

• the present invention relates to a skin-removing method for root and tuber crops.
• Root and tuber crops such as sweet potato, potato, and cassava etc.
• Water is the primary chemical component of fresh root tuber of cassava, and carbohydrate is the second; additionally, cassava also contains a small amount of protein, fat, and pectin.
• the starch content of fresh cassava can reach 25-30wt%, while starch content of dry cassava is about 70wt%.
• Ripe cassava has diameter of about 4-8cm, and length of 20-30cm, which is podgy and in shape of short cylinder.
• Cassava has structure of flesh and skin from inner to outer, wherein the skin comprises inner skin and outer skin.
• the outer skin is in dark brown color, and has spaced white circular strips, and the inner skin and flesh are in white color.
• the skin of cassava contains cyanide and cyanogenic glycoside, linamarin, which is capable of causing food poisoning. Linamarin can generate hydrocyanic acid after being hydrolyzed. Hydrocyanic acid and cyanide are both extremely toxic and can cause acute poisoning. If cyanide toxin is not removed, it may lead to inactivation of enzyme during enzymolysis and inactivation of yeast during fermentation, and thus subsequent enzymolysis and fermentation processes are affected. Therefore, available methods for producing ethanol from root and tuber crops, particularly cassava, generally comprise removing skin of root and tuber crops, and then pulverizing, enzymolyzing, and fermenting.
• the present invention provides a skin-removing method for root and tuber crops by which the skin of root and tuber crops can be effectively removed and the loss of raw material is low.
• the present invention provides a skin-removing method for root and tuber crops by using a skin-removing device comprising: a pedestal 1; a rotary drum 2 rotatably fitted on the pedestal 1 and having an inlet 4 and a outlet 5; a helical screw feeder 3 provided in the rotary drum 2 and fixedly connected with the inner wall of the rotary drum; and a driving unit for driving the rotary drum 2 and the helical screw feeder 3 to rotate together, wherein the method includes feeding raw material of root and tuber crops into the rotary drum 2 via the inlet 4, allowing the driving unit to drive the rotary drum 2 and the helical screw feeder 3 to rotate together.
• raw material of root and tuber crops is fed into the rotary drum via the inlet 4, and the driving unit drives the rotary drum and the helical screw feeder to rotate together.
• the raw material is continuously moved forward, and at the same time the raw material rotates along with the rotary drum and the helical screw feeder.
• friction is generated not only among the raw material, but also between the raw material and the rotary drum wall and the helical screw feeder, so as to remove the skin of the raw material without damaging the flesh of root and tuber crops, such that the loss of raw material is low.
• Fig.l shows the front view of the skin-removing device for root and tuber crops used in the method according to the present invention
• Fig. 2 shows the longitudinal section view of the skin-removing device
• Fig. 3 shows the cross section view representing connection relationship of the chain wheel and the rotary drum.
• the skin-removing method uses a skin-removing device for root and tuber crops.
• the skin-removing device comprises: a pedestal 1; a rotary drum 2 rotatably fitted on the pedestal 1 and having an inlet 4 and a outlet 5; a helical screw feeder 3 provided in the rotary drum 2 and fixedly connected with the inner wall of the rotary drum 2; and a driving unit (not shown in the figures) for driving the rotary drum 2 and the helical screw feeder 3 to rotate together.
• the skin-removing method comprises feeding raw material of root and tuber crops into the rotary drum 2 via the inlet 4, and allowing the driving unit to drive the rotary drum 2 and the helical screw feeder 3 to rotate together.
• the rotation speed of the rotary drum 2 and the helical screw feeder 3 can be 2-50 rpm, preferably 5-25 rpm.
• the raw material Under push action of the helical screw feeder 3, the raw material is continuously moved forward, and at the same time the raw material rotates along with the rotary drum 2 and the helical screw feeder 3. During rotation, friction is generated not only among the raw material, but also between the raw material and the rotary drum wall and the helical screw feeder, so as to remove the skin of the raw material; and the skin-removed material is discharged from the outlet 5.
• the rotary drum 2 can be made from various wear-resistant materials, such as steel, rubber, or rigid plastics.
• the rotary drum 2 can be further provided with spraying unit therein.
• the spraying unit can be fixedly fitted on the inner wall of the rotary drum, and located close to the inlet of the rotary drum.
• the spraying unit can be various common spraying units.
• the spraying unit can remove dirt (such as soil or impurities) on the raw material by spraying water on the material.
• the rotary drum 2 comprises, from inlet end to outlet end, a first section rotary drum 2a and a second section rotary drum 2b which are communicated with each other, and a spraying unit is provided in the second section rotary drum 2b.
• the spraying unit can be fixedly fitted on the inner wall of the second section rotary drum 2b, and located close to the inlet of the second section rotary drum.
• a friction structure may be further provided on the inner wall of the rotary drum 2 in order to achieve better skin-removing effect.
• the friction structure can be various structures with rough surface, preferably one or more ribbed steel bars, more preferably multiple ribbed steel bars.
• the ribbed steel bar has transversal ribs, and can be various conventional hot rolled ribbed steel bar and cold rolled ribbed steel bar, such as ribbed steel bar complying with Chinese National Standard GB 1499- 1998.
• the nominal diameter of the ribbed steel bar can be 6-25 mm, preferably 8-20 mm.
• the interval between the transversal ribs can be 3-16 mm, preferably 4-12mm.
• the grade of the ribbed steel bar includes, but is not limited to, HRB335, HRB400 and HRB500.
• the ribbed steel bar is fixedly connected with the inner wall of the rotary drum 2, such that it can exert friction action to the raw material during rotation of the rotary drum.
• the ribbed steel bar is parallel to the central axis of the rotary drum.
• the rotary drum 2 can be horizontally or obliquely installed on the pedestal 1.
• the raw material is moved forward under push action of the helical screw feeder 3, and finally discharged via the outlet of the rotary drum.
• the rotary drum is obliquely installed, since the position of the inlet is higher than that of the outlet, the raw material can be moved downward under its own gravity action (i.e. moved forward) as well.
• the inclination angle of the rotary drum 2 can be 0-15 degrees, preferably 5-10 degrees.
• the length of the rotary drum 2 can be 2-10 m, preferably 3.5-7 m.
• the length refers to sum of lengths of the first section rotary drum and the second section rotary drum.
• the inclination angle refers to included angle between the central axis of the rotary drum and the horizontal line.
• inner diameter of the rotary drum which can be selected according to the amount of the raw material to be processed. For example, generally, the inner diameter of the rotary drum is 1-2 m.
• the helical screw feeder 3 can be various common helical screw feeders in the mechanical field.
• the helical screw feeder 3 can be connected on the inner wall of the rotary drum 2 via various fixed connection means.
• the helical screw feeder 3 is fixedly connected on the inner wall of the rotary drum 2 via a fastener 8.
• the pitch of the helical screw feeder 3 is preferably 0.3-0.8m, and the height of the screw thread is preferably 0.1 -0.4m.
• the helical screw feeder can be made of various wear-resist materials, such as steel, rubber, or nylon, etc.
• the driving unit may comprise a driving source, a transmission chain, and a chain wheel 6.
• the chain wheel may be fixed on the rotary drum 2.
• the rotary drum 2 comprises the first section rotary drum 2a and the second section rotary drum 2b
• the chain wheel 6 is preferably fitted between the first section rotary drum 2a and the second section rotary drum 2b.
• the chain wheel can drive the rotary drum to rotate when the transmission chain transfers the driving power of the driving source to the chain wheel.
• the rotatable fitting manner can be realized by various common methods, for example, support roller or frame can be adopted to fit the rotary drum on the pedestal to allow the rotary drum to rotate around the central axis.
• the driving source can be various units capable of generating power, such as motor.
• the skin-removing device may further comprise a windmill feeder 7.
• the windmill feeder 7 is fitted at the inlet 4 of the rotary drum.
• the windmill feeder 7 can be various common windmill feeders in the mechanical field.
• the skin-removing device used in the method of the present invention utilizes friction action among raw material and between the raw material and the rotary drum wall to remove skin of the raw material.
• the cyanide removal rate can reach 75% or higher, and raw material loss rate can be kept below 5wt%, indicating that the skin of root and tuber crops can be effectively removed and the loss of raw material is low by the skin-removing method according to the present invention.
• the skin-removing method according to the present invention is suitable for various root and tuber crops, such as sweet potato, potato, and cassava, etc., particularly cassava.
• the cassava material is fresh cassava harvested in same batch, with diameter of 4-8cm, length of 20-30cm, and water content of about 65wt%.
• the skin-removing device is shown in Fig. 1, 2, and 3.
• a rotary drum 2 includes a first section rotary drum 2a and a second section rotary drum 2b from up to down, the first section rotary drum 2a and the second section rotary drum 2b are communicated, and the lengths of the first section rotary drum 2a and the second section rotary drum 2b are respectively 1.8m and 1.6m.
• the rotary drum 2 is made of steel, with inner diameter of 1.6m.
• 40 hot-rolled ribbed steel bars (Grade No. HRB335, and nominal diameter of 12mm) are fixed on the inner wall of the first section rotary drum 2a, parallel to the central axis of the rotary drum, and distributed at equal interval of 0.125m along circumference of the rotary drum inner wall.
• 50 hot-rolled ribbed steel bars (Grade No.
• HRB500 and nominal diameter of 16mm are fixed on the inner wall of the second section rotary drum 2b, parallel to the central axis of the rotary drum, and distributed at equal interval of 0.1m along circumference of the rotary drum inner wall.
• the rotary drum 2 is obliquely fitted on a pedestal 1 at inclination angle of 5 degrees.
• a driving device comprises a motor, a transmission chain, and a chain wheel 6.
• the chain wheel is fixed on the rotary drum 2, the transmission chain transfers the power of the motor to the chain wheel, and the motor has a power of 5.5kW.
• the motor is started to drive the rotary drum 2 and the helical screw feeder 3 to rotate around the central axis of the rotary drum at 7rpm.
• the harvested cleaned fresh cassava 100kg are continuously fed into the rotary drum 2 via the inlet 4, and the skin-removed cassava is discharged from the outlet 5 to obtain skin-removed cassava material 96kg.
• the calculated cyanide removal rate is 75%.
• the loss of raw material is low and cyanide removal rate is high by using the skin-removing method according to the present invention, indicating that the skin of root and tuber crops can be effectively removed and the loss of raw material is low by using the skin-removing method according to the present invention.

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• Life Sciences & Earth Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Polymers & Plastics (AREA)
• Apparatuses For Bulk Treatment Of Fruits And Vegetables And Apparatuses For Preparing Feeds (AREA)

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Citations (4)

• 2008
  • 2008-01-15 CN CN200810056218A patent/CN100586315C/zh active Active
  • 2008-12-31 WO PCT/CN2008/073881 patent/WO2009092275A1/en active Application Filing

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