WO2010129648A2

WO2010129648A2 - Starch separation process

Info

Publication number: WO2010129648A2
Application number: PCT/US2010/033685
Authority: WO
Inventors: Gang Duan; Ying Qian; Jayarama Shetty; Soo Kiang Tok; Hongwei Zhou
Original assignee: Danisco Us Inc.
Priority date: 2009-05-07
Filing date: 2010-05-05
Publication date: 2010-11-11
Also published as: WO2010129648A3; CN102414322A

Abstract

The present invention relates to a new process for separating starch from starch-bearing tubers using one or more enzymatic treatments to the tuber material at various stages of the starch separation process to increase starch extraction. Based on the underlying crop material and the type of separation process used, the particular enzymes or enzyme combinations may be selected to optimize the starch extraction yield.

Description

STARCH SEPARATION PROCESS

PRIORITY The present application claim priority to U.S. Provisional Application Serial No.

61/176,365, filed on May 7, 2009, which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION The present invention is directed to a new process for separating starch from starch-bearing crops, and particularly to a process involving one or more enzymatic treatments during the separation process to increase starch extraction from tubers, including cassava.

BACKGROUND

Cassava (Manihot esculenta Crantz) is a member of the Euphorbiaceae family, and because of its storage root, it is cultivated in tropical regions as a source of food. Ground cassava is known as tapioca. Like other crops, such as rice, sugar cane and maize, cassava is a major source of calories and is a staple food for hundreds of millions of people in Africa, Latin America and Asia. This is due to the fact that there are many advantages of utilizing cassava for starch production. For example, cassava offers a relatively cheap source of raw material containing a high concentration of starch (dry matter basis) that can at least match or even better the properties offered by other starches from crops such as maize, wheat, sweet potato and rice. One of the many uses for the cassava root is for tapioca starch production.

The isolation of starch from the root has historically depended on mechanical methods. Generally, after washing and peeling, the roots are grated to release starch granules. The water containing suspended granules, known as "starch milk", is then separated from the pulp, after which the granules are separated from the water by sedimentation or centrifugation. At that point, the starch requires natural or artificial drying to remove moisture before being milled, sieved and packed. However, these standard mechanical methods are not without their drawbacks. For example, the traditional process includes a long processing time due to the drying of the starch by natural (solar) methods. This extended processing time also leads to a loss of product yield and quality, due in part to variations in humidity and the increased possibilities of rot and contamination. In another example, more modern processes, which typically incorporate flash drying to reduce the processing time, require factories that demand a high level of capital investment, are costly to operate and require highly skilled labour to maintain the equipment. Additionally, these factories must have a reliable electricity supply available throughout the process. In those parts of the world where cassava is grown and harvested, these requirements create very high barriers to overcome.

In any case, cassava producers must choose between lower yields and quality, or the financial burden of operating a modern facility when separating starch. Therefore, a need still exists for methods of improving and enhancing starch extraction yields.

SUMMARY

A method of separating starch from cassava root is described. In one embodiment, the method includes the steps of at least partially de-barking the cassava root, chopping or grinding the cassava root to form a mash, separating fibrous residue from the mash by passing the mash through at least one filtration device, incubating the mash with at least one hydrolytic enzyme, and drying the mash to form a cassava cake containing the starch. In certain embodiments, the hydrolic enzyme is a cellulase, a protease, a pectinase, a combination of a pectinase and a protease, or a combination of a pectinase, a cellulase, and a protease. In another embodiment, the step of separating fibrous residue from the mash includes passing the mash through at least one filtering device. In another embodiment, incubation with at least one hydrolytic enzyme occurs between mash passages through at least one filtering device. In yet another embodiment, the incubating of mash with at least one hydrolytic enzyme occurs in more than one incubation period. In another embodiment, starch extraction from the at least one cassava root is at least about 10% greater than starch extraction from at least one cassava root that is not treated with a hydrolytic enzyme. A method of separating starch from a tuber is also described. The method includes the process of mashing the tuber into a mash or slurry, and incubating the mash or slurry with at least one hydrolytic enzyme to increase starch extraction from the mash or slurry as compared to the starch extracted when the mash or slurry is not incubated with a hydrolytic enzyme. In one embodiment, the starch is separated from the mash or slurry by passing the mash or slurry at least two times through a filtering device. In another embodiment, the mash or slurry is incubated with the at least one hydrolytic enzyme between passages of the mash or slurry through the filtering device. In other embodiments, at least one hydrolytic enzyme is a pectinase, a cellulase, a protease, a combination of two or more hydrolytic enzymes of the group consisting of pectinase, cellulase and protease.

A substantially isolated starch product is also described. The product is obtained from a tuber that has been separated by mashing the tuber into a mash or slurry, and incubating the mash or slurry with at least one hydrolytic enzyme to increase starch production from the mash or slurry as compared to the starch produced when the mash or slurry is not incubated with a hydrolytic enzyme. In one embodiment, the starch is separated from the mash or slurry by passing the mash or slurry two or more times through a filtering device. In another embodiment, the mash or slurry is incubated with the at least one hydrolytic enzyme between passages of the mash or slurry through the filtering device. In other embodiments, the at least one hydrolytic enzyme is a pectinase, a cellulase, a protease, or a combination of two or more of the group consisting of pectinase, cellulase, and protease.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 depicts a flow chart of the general stages in the separation of starch from cassava root. There are three primary points (A-C) in the generalized separation process that are preferable time periods for treatment of the cassava mash or slurry with enzymes for increased starch extraction.

DETAILED DESCRIPTION Cassava, or tapioca, is a relatively cheap source of raw material containing a high concentration of starch. The present invention provides a new process for separating starch from starch-bearing tubers by implementing one or more enzymatic treatments to the crop material at various stages of the separation process to increase starch extraction. Based on the underlying crop material and the type of separation process used, the particular enzymes or enzyme combinations may be selected to optimize the starch extraction.

1. Definitions Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Still, certain terms are defined below for the sake of clarity and ease of reference.

The terms "active", "activity" and "biologically active" refer to a biological activity associated with a particular enzyme. It follows that the biological activity of a given enzyme refers to any biological activity typically attributed to that enzyme by those skilled in the art. For example, an enzymatic activity associated with a pectinase is hydrolytic and, thus an active pectinase has hydrolytic activity.

The term "tuber" as used herein means a swollen and/or fleshy stem or root portion of a plant. Examples of tubers may be, without limitation, cassava, potato, yam, taro, beet, carrot, ginger, onion, garlic and chicory root.

The term "de-barking" refers to the process of removing the bark from a plant.

The cassava root includes a thin, reddish-brown, fibrous bark that is removed by peeling.

The term "partial de-barking" as used herein refers to an imperfect removal of the cassava root bark. While complete removal of the bark is preferred, a partial de-barking reflects that not all of the bark was actually removed.

The terms "mash" and "slurry" as used herein both refer to the consistency of the crushed root material. The crushed root will more resemble a "mash" when there is less water forming part of the mixture, and "slurry" when there is more water forming part of the mixture. Generally, when the water content is between about 50-80% the crushed root material will resemble a mash, and when the water content is between about 70-90% the crushed root material will resemble a slurry. As used herein, the process of "mashing" is the conversion of a solid material into a mash or a slurry.

The term "filtration" (or the activity of "filtering") as used herein means the separating of liquids from solids, or of particles within a fluid medium based on particle size. Filtering may be performed by any filtration device and/or mechanism, including mesh, sieve, net, screen, strainer, centrifuge or distiller. The material being filtered is passed through the filtration device, such that, based on size of the pores of the filtration device, smaller particles pass through the filtration device, while larger particles do not. The term "hydrolytic enzyme" means an enzyme that catalyzes the hydrolysis of a chemical bond. Without limitation, hydrolytic enzymes may be pectinases, cellulases and proteases.

The term "substantially isolated starch" means a compound substantially free of cell components with which the starch may naturally occur, or any reagents used or the byproducts of a reaction. "Substantially isolated" does not mean that the preparation is technically pure (homogeneous), but the starch is sufficiently separated to provide the starch in a form in which it can be prepared for commercial use.

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

Before the exemplary embodiments are described in more detail, it is to be understood that this disclosure is not limited to particular embodiments described, as such may, of course, vary. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure, exemplary methods and materials are now described.

As used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a gene" includes a plurality of such candidate agents and reference to "the cell" includes reference to one or more cells and equivalents thereof known to those skilled in the art, and so forth.

The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present disclosure is not entitled to antedate such publication by virtue of prior invention.

2. Abbreviations

DS dry substance pH potential of Hydrogen tds total dissolved solids

Wt % weight percent

⁰C degrees Centigrade kD kilodaltons g or gm grams μg micrograms mg milligrams μl and μL microliters ml and mL milliliters mm millimeters μm micrometer

M molar mM millimolar μM micromolar

U units

MW molecular weight sec(s) or s(s) second/seconds min(s) or m(s) minute/minutes hr(s) or h(s) hour/hours m/v mass/volume N Normal

3. Enzymes for Treatment of Starch-Bearing Tubers

As contemplated herein, a number of enzymes are used, either separately or in various combinations, to increase the extraction of starch from starch-bearing tubers. For example, to aid in the hydrolyzing of pectin or other polysaccharides that are present in plant cell walls and in the middle lamella between plant cells, a pectinase can be used. As contemplated herein, pectinases derived from (or designed after) any source may be used, such as from fungi or bacteria. For example, without limitation, use of pectinases such as protopectinases, esterases and depolymerases are contemplated herein. In certain embodiments, pectinases such as pectinesterase, pectin pectylhydrolase, galacturan 1,4-α-galacturonidase, exo-poly-α-galacturonidase, pectate lyase, pectate disaccharide-lyase, oligogalacturonide lyase and pectin lyase may be used. In a preferred embodiment, PECTINASE^® FE (Genencor-Danisco) is used. Other suitable, commercially available pectinases include PECTINEX^® and Ultra PEELZYM^® (Novozymes), Pectinase G and Pectinase PL (Amano); Pectinase 3S, Pectinase SS,

Pectinase HL, Macerozyme A and Macerizyme S (Yakult), Rapidase Intense, Rapidase^® PRESS; Rapidase^® SMART, Rapidase^® ADEX-D, CITRUS CLOUDY; Rapidase^® C80 MAX (DSM), and GAMMAPECT PCL and ROHA VIN^® CXL (AB Enzymes), for example. In another embodiment, multiple pectinases are used. It should be appreciated that any enzyme having pectinase-like activity, as understood by those skilled in the art, may be used. Pectinases, as contemplated herein, may have optimal activity in conditions having between about 2-10 pH, more preferrably between about 4-5 pH, and a temperature of between about 30-60⁰C. Pectinases having activity outside these conditions may also be used, but are not preferable. The amount of pectinase used may range from about 0.01-5.0 kg/tds, preferrably about 0.1 to 1.0 kg/tds, and more preferrably about 0.5 kg/tds (or kg /MT ds). The amount of pectinase used may also be determined based on Units. The amount of pectinase used in any particular reaction may be altered based on the incubation time, pH and temperature chosen for the enzymatic reaction.

In another example, a cellulase may be used to hydrolize certain polysaccharide chains, such as cellulose, that are found in plant cell walls. As contemplated herein, cellulases derived from (or designed after) any source may be used, such as from fungi, bacteria, protozoans, plants or animals. For example, without limitation, use of cellulases such as endo-cellulase, exo-cellulase, cellubiase, oxidative cellulases and cellulose phosphorylases are contemplated herein. In a preferred embodiment, ACCELLERASE^® (Genencor-Danisco) is used. In another embodiment, multiple cellulases are used. It should be appreciated that any enzyme having cellulase-like activity, as understood by those skilled in the art, may be used. It should be appreciated that any enzyme having cellulase-like activity, as understood by those skilled in the art, may be used, such as ROVABIO^® (Adisseo), NATUGRAIN^® (BASF), MULTIFECT^® BGL (Danisco US, Inc., Genencor Division), Viscozyme (Novozymes) and ECONASE^® (AB Enzymes). Cellulases, as contemplated herein, may have optimal activity in conditions having between about 2-10 pH, more preferrably between about 4-5 pH, and a temperature of between about 30-60⁰C. Cellulases having activity outside these conditions may also be used, but are not preferable. The amount of cellulase used may range from about 0.01- 5.0 kg/tds, preferrably about 0.1 to 1.0 kg/tds, and more preferrably about 0.5 kg/tds. The amount of cellulase used may also be determined based on Units. The amount of cellulase used in any particular reaction may be altered based on the incubation time, pH and temperature chosen for the enzymatic reaction.

In another example, a protease may be used to hydrolize polypeptide chains or proteinaceous complexes found in the subject plant material. Any sort of protease or combination of proteases may be used, such as serine, cystine, aspartate, threonine and glutamic acid proteases and metalloproteases, for example. As contemplated herein, proteases derived from (or designed after) any organism may be used. For example, proteases such as Papain and Bromalien (from plants), or Pancreatin, Trypsin and Pepsin (from animals) as well as fungal, bacterial or other microorganism may be used. In another words, proteases exhibiting activity in acidic, neutral and alkaline pH may all be suitable. In a preferered embodiment, ProSteep" (Genencor-Danisco) is used. Other suitable, commercial proteases may include Alcalase^®, Neutrase^®, Protamex^®, and Novo- Pro™ (Novozymes), and PROTEX, MULTIFECT P3000 and Neutral (GENENCOR). While various proteases have activity across a wide range of pH and temperature conditions, as contemplated herein, preferrable conditions are between about 2-10 pH, more preferrably between about 4-5 pH, and a temperature of between about 30-60⁰C. The amount of protease used may range from about 0.01-5.0 kg/tds, preferrably about 0.1 to 1.0 kg/tds, and more preferrably about 0.5 kg/tds. The amount of protease used may also be determined based on Units. The amount of protease used in any particular reaction may be altered based on the incubation time, pH and temperature chosen for the enzymatic reaction.

As mentioned previously, these enzymes may be used separately or in various combinations to increase starch extraction. Exemplary combinations, by non-limiting example only, are pectinase and cellulase, pectinase and protease, cellulase and protease, and pectinase, cellulase and protease. Other such combinations, such as a pectinase and multiple proteases, or pectinase and multiple cellulases, for example, may also be used. It should be appreciated that the present invention, as contemplated herein, is not limited by any particular use or combination of the aforementioned enzymes.

Incubation times with individual enzymes or enzyme combinations may range from about 10 minutes to 8 hours. In one embodiment, enzymatic treatment of the cassava product is about one hour. In other embodiments, incubation periods may vary between enzyme types within an enzyme combination. For example, an enzyme combination of pectinase and protease may involve an incubation time of pectinase alone for about 1 hour, followed by a subsequent incubation of a pectinase and protease combination for about an hour. It should be appreciated that the hydrolysis of the subject material is increased with longer incubation periods, provided enzymatic conditions remain constant.

4. Enzymatic Treatment During Starch Processing As contemplated herein, the aforementioned enzymes are used in the process of starch separation to increase starch extraction. As previously described, standard processes for the production of native starch from cassava root involves the following major stages: root washing and debarking, chopping and grinding, starch and fibrous residue separation, dewatering, and drying. Without limitation, any standard, non- enzymatic starch separating process may form the basis of the novel enzymatic treatment processes for increased starch extraction. For example, there are two main methods for industrial processing of native cassava starch - the traditional approach, and the "Alfa Laval type" approach used for large-scale industrial processes.

In the traditional process, fresh roots are washed and de-barked before crushing in a rotary rasper to form a mash or slurry, or any other means known in the art for crushing the roots. Starch is then separated from the crushed pulp, and filtered via passage through a series of reciprocating nylon screens, or mesh, that decreases in pore size. For separation, mesh ranging from about 5 mesh to 200 mesh may be used. For example, 10 mesh, 20-40 mesh, and/or 100-200 mesh may be used. As contemplated herein, any form of filtration device may be used, including without limitation, mesh, netting, screens, sieves, strainers, distillers or centrifuge, for example, provided particle sizes do not become so small as to negatively affect throughput. The resultant starch milk settles over a period of about 4-8 hours using a shallow settling table or a series of inclined channels, often laid out in a zigzag pattern. Settled starch is then sun dried on large cement drying floors for approximately 8 hours. During this period, the moisture content typically reduces from 45-50% down to 10-12%. To achieve efficient drying, sunny conditions are required with ambient temperatures of >30°C and relative humidity of about 20-30%. Dried starch is then ground to a fine powder and packaged for sale.

In the more modern "Alfa Laval type" process, roots are similarly washed and debarked, sliced and then crushed in a rotary rasper. Starch pulp is then passed through two conical rotary extractors to separate starch granules from fibrous materials, and then fed via a protective safety screen and hydro cyclone unit to a continuous centrifuge for washing and concentration. The concentrated starch milk is then passed through a rotary vacuum filter to reduce water content to about 40-45% and then flash dried. The flash drying reduces moisture content to about 10-12% in a few seconds, so starch granules do not heat up and suffer thermal degradation. As depicted in Figure 1, these stages are further generalized, with the insertion of enzymatic treatment periods in any one or more of points A, B or C. Water may be added during any of points A, B or C, as needed to the mash or slurry. For example, at point A, after the rasper and screening stage, the pH may be adjusted by standard methods for optimal enzyme activity, and the cassava mash may be incubated for a set time at an optimized temperature for the enzymes or enzyme combination used. In another example, at point B, the pH and temperature may be similarly adjusted after the first fine extraction for an optimal enzymatic treatment period. Likewise, at point C, the pH and temperature may be adjusted after the second fine extraction for an optimal enzymatic treatment period. In other embodiments, there may be multiple enzyme treatment periods. For example, a first enzyme treatment may be performed at point A, followed by a second and/or third enzyme treatment at point B and/or C, respectively. It should be appreciated that any number of enzyme treatments can be performed at various points in the starch separation process, as would be understood by those skilled in the art. In yet another embodiment, where multiple enzyme treatment periods are used, each particular enzyme treatment period may be similar or different. For example, a first treatment involving an enzyme combination of pectinase and protease may be performed at point A, and a second enzyme treatment involving a cellulase may be performed at point B. Again, it should be understood that any combination of the aforementioned enzymes, incubation times and points of enzyme treatment in the starch separation process as described herein may be used, such that the extraction of starch from the subject starch-bearing tuber is increased.

EXAMPLES Example #1 - Individual Enzyme Types

Fresh cassava root was peeled with a knife, and dry sustenance in the fresh root was checked by the moisture balance. The moisture content of which was about 75-82% on average. Depending on the actual DS in fresh root, tap water was added to make about a 10-15% DS mash. The peeled root was then weighed, cut into small pieces and milled by a grinder. During the milling process, tap water was added to the mash as needed, and the final milled mash was passed through a 20-mesh sieve. From this, an aqueous slurry containing 15% cassava (dry substance based) was prepared. The mash pH was adjusted to about 4.0 with 20% hydrochloric acid. The mash was then split into 4 separate samples containing about 300g mash, respectively. As depicted in Table 1, various enzymes (PECTINASE^® FE, ProSteep^® and ACCELLERASE^® L 1000) were added to samples 1-3, respectively.

Table 1

The mash was heated to about 40⁰C and held at temperature for about an hour. After the incubation period, the enzyme-treated mash was washed with tap water and passed through 120-mesh sieve. The cassava pulp remaining above the sieve was collected. The filtered slurry was centrifuged to yield a starch cake. Finally, the cassava starch cake and the cassava pulp were dried in an oven at about 55⁰C overnight.

As depicted in Table 2, the aforementioned process from about 300 g of cassava mash resulted in total starch of approximately 13.85% DS, about 41.55 g of dry substance weight, a starch content of about 84.67% and a dry starch weight of about 35.18g.

Table 2

Total starch in fresh cassava root

As can be seen in Table 3, the starch extraction in sample #1 (treated with Pectinase FE) was about 66.77%, and in sample #2 (treated with ProSteep) was about 65.11% as compared to the control sample (blank), which provided starch extraction of about 61.4%.

Table 3

Cassava starch

Example #2 - Enzyme Combinations

Fresh cassava root was peeled with a knife, and dry sustenance in the fresh root was checked by the moisture balance. The moisture content of which was about 75-82% on average. Depending on the actual DS in fresh root, tap water was added to make about a 10-15% DS mash. The peeled root was then weighed, cut into small pieces, and milled by a grinder. During the milling process, tap water was added to the mash as needed, and the final milled mash was passed through a 20-mesh sieve. From this, aqueous slurry containing about 15% cassava (dry substance based) was prepared. The mash pH was adjusted to about 4.0 with 20% hydrochloride acid. The mash was then split into 4 separate samples containing about 300 g mash, respectively. As depicted in Table 4, various enzymes in particular combinations were added by weight (DS based).

Table 4

The mash was heated to about 4O⁰C and held at that temperature for about an hour. After the incubation period, the enzyme-treated mash was washed with tap water and passed through a 120-mesh sieve. The cassava pulp remaining above the sieve was collected. The filtered slurry was centrifuged to produce a starch cake. Finally, the cassava cake and the cassava pulp were dried in an oven at about 55⁰C overnight.

As depicted in Table 5, the aforementioned process from about 300 g of cassava mash resulted in total starch of approximately 15% DS, about 45 g of dry substance weight, a starch content of about 84.67% and a dry starch weight of about 38.1g.

Table 5

Total starch

As can be seen in Table 6, the starch content in sample #1 (treated with PECTINASE^® FE and ACCELLERASE^® L 1000) was about 66.5%; in sample #2 (treated with PECTINASE^® FE and ProSteep^®) it was about 72.08%; and in sample #3 (PECTINASE^® FE, ACCELLERASE^® L 1000 and ProSteep^®) it was about 68.47%.

Table 6

Cassava starch cake

Various modifications and variations of the described invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific representative embodiments, it should be understood that the subject matters as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention that are obvious to those skilled in the art are intended to be within the scope of the following claims.

All references discussed herein are incorporated herein by reference for all purposes.

Claims

WHAT IS CLAIMED IS:

1. A method of separating starch from cassava root, comprising the steps of: at least partially de-barking the cassava root; chopping or grinding the cassava root to form a mash; separating fibrous residue from the mash by passing the mash through at least one filtration device; incubating the mash with at least one hydrolytic enzyme; and drying the mash to form a cassava cake containing the starch.

2. The method of claim 1, wherein the at least one hydrolytic enzyme is a pectinase.

3. The method of claim 1, wherein the at least one hydrolytic enzyme is a cellulase.

4. The method of claim 1, wherein the at least one hydrolytic enzyme is a protease.

5. The method of claim 1, wherein the at least one hydrolytic enzyme is a combination of a pectinase and a cellulase.

6. The method of claim 1, wherein the at least one hydrolytic enzyme is a combination of a pectinase and a protease.

7. The method of claim 1, wherein the at least one hydrolytic enzyme is a combination of a pectinase, a cellulase, and a protease.

8. The method of claim 1, wherein the step of separating fibrous residue from the mash includes passing the mash through at least one filtering device.

9. The method of claim 8, wherein incubation with at least one hydrolytic enzyme occurs between mash passages through at least one filtering device.

10. The method of claim 9, wherein the incubating of mash with at least one hydrolytic enzyme occurs in more than one incubation period.

11. The method of claim 1 , wherein starch extraction from the at least one cassava root is at least about 10% greater than starch extraction from at least one cassava root that is not treated with a hydrolytic enzyme.

12. A method of separating starch from a tuber, comprising mashing the tuber into a mash or slurry, and incubating the mash or slurry with at least one hydrolytic enzyme to increase starch extraction from the mash or slurry as compared to the starch extracted when the mash or slurry is not incubated with a hydrolytic enzyme.

13. The method of claim 12, wherein the starch is separated from the mash or slurry by passing the mash or slurry at least two times through a filtering device.

14. The method of claim 13, wherein the mash or slurry is incubated with the at least one hydrolytic enzyme between passages of the mash or slurry through the filtering device.

15. The method of claim 14, wherein the at least one hydrolytic enzyme is a pectinase, a cellulase, or a protease.

16. The method of claim 15, wherein the at least one hydrolytic enzyme is a combination of two or more hydrolytic enzymes of the group consisting of pectinase, cellulase and protease.

17. The method of claim 16, wherein the at least one hydrolytic enzyme is a combination of pectinase, cellulase, and protease.

18. A substantially isolated starch product obtained from a tuber that has been separated by mashing the tuber into a mash or slurry, and incubating the mash or slurry with at least one hydrolytic enzyme to increase starch production from the mash or slurry as compared to the starch produced when the mash or slurry is not incubated with a hydrolytic enzyme.

19. The product of claim 18, wherein the starch is separated from the mash or slurry by passing the mash or slurry two or more times through a filtering device.

20. The product of claim 19, wherein the mash or slurry is incubated with the at least one hydrolytic enzyme between passages of the mash or slurry through the filtering device.

21. The product of claim 20, wherein the at least one hydrolytic enzyme is a pectinase, a cellulase, or a protease.

22. The product of claim 21, wherein the at least one hydrolytic enzyme is a combination of two or more of the group consisting of pectinase, cellulase, and protease.

23. The product of claim 22, wherein the at least one hydrolytic enzyme is a combination of pectinase, cellulase, and a protease.

24. The product of claim 18, wherein the tuber is cassava root.