Process for preparing dextrins

Details Process for preparing dextrins Process for preparing dextrins

2001-02-28

2003-12-30

Prats, Francisco (Department: 1651)

Chemistry: molecular biology and microbiology

Micro-organism, tissue cell culture or enzyme using process...

Preparing compound containing saccharide radical

C435S072000, C435S099000, C435S101000, C536S103000

Reexamination Certificate

active

06670155

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
This invention is in the field of oligosaccharides, and in particular, the invention pertains to the preparation of a high molecular weight dextrin product.
BACKGROUND OF THE INVENTION
Certain enzymes, known as beta-amylase enzymes, are known to act on starch to produce low molecular weight species, typically maltose, and high molecular weight species, known as dextrins. With the exception of so-called waxy (corn) or glutinous (rice) starches, most starches found in nature are composed of a mixture of amylopectin and amylose. Amylose is a linear molecule which is substantially completely hydrolyzed by beta-amylase enzymes into maltose and glucose. Amylopectin, a branched molecule, is hydrolyzed into maltose and higher molecular weight dextrins, because the beta-amylase enzyme is unable to hydrolyze past the alpha 1-6 branch point in the amylodextrin molecule. If the enzymatic hydrolysis is allowed to proceed to its fullest extent, the remainder of the amylopectin molecule will exist as what is known as beta-limit dextrin.
Despite the potentially numerous commercial uses for such high molecular weight dextrins, it is believed that no such dextrins are sold commercially in bulk quantities. Present enzymatic processes yield a mixture of products from which it is difficult to resolve such dextrins. The present invention seeks to provide a process for preparing dextrins, such as beta-limit dextrin, in which this difficulty is overcome.
THE INVENTION
It has now been found that the treatment of starch with an enzyme that consists essentially of a beta-amylase enzyme, and which is to the substantial exclusion or complete exclusion of alpha-amylase enzymes and de-branching enzymes, will yield a product mixture that includes a dextrin and one or more low molecular weight sugars. The low molecular weight sugar or sugars may be readily separated from the product mixture thus formed via ultrafiltration to yield a dextrin in the retentate. If desired, diafiltration may be used to separate substantially all of the low molecular weight sugars from the dextrin in the retentate.
Retrograded amylose may be removed from the product mixture prior to ultrafiltration. In accordance with another embodiment, the invention provides a method for preparing retrograded amylose. It is contemplated that this material is useful as “resistant” starch, which is not as digestible as other starches and which therefore may be used as a low- or non-caloric bulking agent.
The dextrins thus prepared will have a number of desirable properties, including a high solubility and a high molecular weight, with low hazing in solution. Additionally, the dextrins have a very low dextrose equivalent value (DE), and thus are expected to be substantially more stable than carbohydrates of lower molecular weight. As such, it is contemplated that such dextrins may be used in applications such as viscosifiers or as spray drying aids for other carbohydrates (such as maltose). In accordance with another embodiment of the invention, the dextrin is added to maltose in an amount sufficient to assist in spray drying.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention contemplates the production of dextrins, such as beta-limit dextrin, from starch. Any suitable starch may be employed in connection with the invention, and thus, for instance, starches such as corn, rice, wheat, tapioca, maize, potato, barley, oat, and, more generally, any starch suitable for enzymatic hydrolysis may be used in connection with the invention. It is not necessary to use a so-called waxy or glutinous starch in connection with the invention, but to the contrary the starch can have any suitable amylose content, such as an amylose content of 10%, 15%, 20%, 25%, or a greater amylose content. It is contemplated that the starch may be a partially derivatized or otherwise modified starch, or may be a starch that has been thinned or enzymatically treated. For instance, a starch that has been lightly oxidized may be employed.
The starch should be liquefied via heat, enzymatic, or acid treatment prior to treatment with the beta-amylase enzyme. Preferably, the starch is liquefied via acid treatment, although low amylose starches may require liquefaction only with heat and may be suitably liquefied at the operating temperature of the enzymatic hydrolysis. As disclosed in more detail in copending application Ser. No. 09/796,027, filed Feb. 28, 2001 by Richard L. Antrim and Clark P. Lee and hereby incorporated by reference, it is desirable to recover maltose from the beta-amylase hydrolysis product. Thus, in general, the starch should be liquefied to an extent such that it would remain liquid at the operating temperature of the beta-amylase hydrolysis, but not liquefied to an extent such that the starch is converted to saccharides having so low a degree of polymerization that it is difficult to separate such saccharides from maltose via ultrafiltration. In other words, the degree of liquefaction should be such that, upon enzymatic hydrolysis with the beta-amylase enzyme, the combined content of glucose and oligosaccharides in the DP 3-10 range does not (exceed about 10%, and preferably does not exceed about 5%. It has been found acceptable to liquefy the starch to a dextrose equivalent (DE) value of about 2, as measured via conventional techniques. Generally, the DE of the starch should be kept below about 1, and thus the DE should range between 0 and about 1, although it may be difficult to measure the DE with precision in this range. For corn starch, it is preferable that the starch is liquefied in an aqueous solution at a liquefaction temperature ranging from about 220° F. to about 320° F., and for a time ranging from about 5 minutes to about 30 minutes.
The starch solids level preferably ranges initially from about 5% to about 30%, more preferably, from about 15% to about 30%. While it is not intended to limit the invention to a particular theory of operation, it is believed that a lower solids content requires a lesser degree of liquefaction to attain the desired viscosity range. In the case of dent corn starch, it has been found that a viscosity window of between 25 and 45 centipoise (Norcross Shell Cup) is optimal. In the case of waxy starches, viscosities outside this range may be acceptable. The pH of the starch slurry should be adjusted to a level sufficient to provide controlled acid hydrolysis of the starch in the presence or absence of catalyzing alpha amylase enzymes; most preferably, under a given set of conditions, the variability of the slurry pH should be no more than +/−0.1 pH, with the precise pH value depending upon the starch source, the slurry solids, and the operational conditions of the liquefaction equipment employed. As a practical matter, the pH can vary more widely while still resulting in a satisfactory product. Preferably, the starch liquefaction is monitored via viscosity and adjusted accordingly.
In accordance with one embodiment of the invention, the starch is liquefied with an alpha-amylase enzyme to reduce the molecular weight of the starch, thereby reducing the viscosity of the starch and thereby permitting processing at a higher solids level. Suitable commercial liquefying enzymes may be obtained from Genencor International, Inc. or from Novozymes A/S. The dosing level of the alpha-amylase enzyme depends upon the desired solids level and, when maltose is recovered as a co-product, on the desired maltose purity. Desirably, the dosing level ranges from about 0.005% to about 0.02% of a commercial strength enzyme by dry solids basis starch. In this embodiment, the alpha-amylase enzyme preferably is quenched prior to saccharification via any suitable quenching procedure. For instance, when the starch is liquefied at a temperature less then 250° F. and 5 minutes residence, the alpha-amylase enzyme is quenched by reducing the liqefact pH to less than 4.0 and holding at a temperature of from 180 to 190° F. for at least about 15 minutes.
Upon liquefaction, the liquefact is immediately cooled and the

Affiliated with

Also associated with

Rating

Process for preparing dextrins does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Process for preparing dextrins, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for preparing dextrins will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3104458