Chemistry: molecular biology and microbiology – Micro-organism – tissue cell culture or enzyme using process... – Preparing compound containing saccharide radical
Reexamination Certificate
1999-12-28
2002-02-12
Lilling, Herbert J. (Department: 1651)
Chemistry: molecular biology and microbiology
Micro-organism, tissue cell culture or enzyme using process...
Preparing compound containing saccharide radical
C435S094000, C435S096000, C435S101000
Reexamination Certificate
active
06346400
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the preparation of a maltose-rich syrup. It also relates to the use of a maltose-rich syrup obtained by the process according to the present invention for the preparation of a maltitol-rich syrup. It also relates to the use of a maltose-rich syrup obtained by the process according to the present invention for the preparation of crystallised maltitol.
2. Description of the Prior Art
Processes by which maltose-rich syrups can be obtained are already well known. These processes include, in particular, the one described by HODGE and co-workers in “Cereal Chemistry” no. 25, pages 19-30, January 1948 and which comprises a step involving the precipitation of limit dextrins by alcoholic solutions, and the one described by WOLFROM and THOMPSON in “Methods in carbohydrate chemistry”, 1962, pages 334-335.
Other processes for the preparation of maltose-rich syrups have also been proposed comprising a step involving adsorption of dextrins over carbon (U.S. Pat. No. 4,194,623), a step involving chromatography over zeolites or cationic or anionic resins (FR-A-2,510,581), a step involving ultrafiltration of maltose syrups (U.S. Pat. No. 4,429,122), the combined use of several different enzymes namely an &agr;-amylase, a &bgr;-amylase and an isoamylase or a pullulanase (FR-A-2,012,831)
This latter method has numerous advantages over the previous ones. Nevertheless, it suffers from certain disadvantages including, in particular, the fact that the saccharification operations have to be carried out with very low dry matter contents of the order of 20 g/l in order to obtain maximum effectiveness of hydrolysis with enzymes.
The document FR-A-2.000.580 describes a process for the preparation of a syrup with a high maltitol content by hydrogenation of a syrup with a high maltose content which is obtained by liquefaction of a starch milk with a low dry matter content to a dextrose equivalent of less than 2, the product thus obtained being saccharified under the action of specific enzymes.
This process is expensive, has a mediocre yield and gives rise to problems of bacterial contamination and phenomena of retrogradation of the amylose. Moreover, the syrup obtained contains proportions of polymers with degrees of polymerisation (DP, in the description hereinafter) greater than or equal to 4, which are troublesome.
More recently, the document U.S. Pat. No. 5,141,859 proposed a process for the preparation of a syrup with a high maltose content employing two successive saccharification steps. This document advocates, in fact, a process comprising a first saccharification step in the presence of a &bgr;-amylase and a subsequent saccharification step in the presence of a maltogenic &agr;-amylase. According to this document, the maltogenic &agr;-amylase is used after the first saccharification step with &bgr;-amylase to hydrolyse the oligosaccharides (from DP3 to DP7) and essentially the maltotriose (trisaccharide) to maltose and glucose.
Although the use of maltogenic &agr;-amylase makes it possible, effectively and advantageously, to lower the maltotriose proportion by hydrolysis of the latter to maltose and glucose, it nevertheless has the major disadvantage of generating large quantities of glucose and possibly sorbitol in the event of hydrogenation of the hydrolysates. In fact, a large proportion of glucose originating from the hydrolysis of maltotriose by the maltogenic &agr;-amylase is added to the residual glucose obtained after saccharification of the liquefied starch milk.
These large quantities of glucose, therefore of sorbitol after hydrogenation, make the crystallisation of maltitol more difficult and lead to a reduction in the crystal content, making these crystals ill-suited to certain applications such as, for example, chocolate production.
Moreover, the persistence of free glucose or sorbitol in the maltose or maltitol syrups bring about other disadvantages such as a reduction in the viscosity and equilibrium moisture content of the products in which they are incorporated as sugar substitutes.
In as much as there is a growing interest in products with a very high maltose content, there is a need for considerable research with a view to developing an economical and extremely reliable process for obtaining such products.
DETAILED DESCRIPTION OF THE INVENTION
In an extremely simple and particularly effective manner with regard to all the proposals to date, the Applicant company observed that syrups with a very high maltose content could be prepared by carrying out molecular sieving of a liquefied and saccharified starch milk so as to collect a fraction enriched with maltose and a fraction enriched with glucose, then bringing said fraction enriched with maltose into contact with a maltogenic &agr;-amylase.
The invention proposes, therefore, a process for the preparation of a maltose-rich syrup comprising the successive steps consisting in:
(a) carrying out liquefaction of a starch milk;
(b) carrying out saccharification of the liquefied starch milk in the presence of a &bgr;-amylase and at least one debranching enzyme selected from the group comprising pullulanases and isoamylases;
(c) carrying out molecular sieving of the liquefied and saccharified starch milk so as to collect a fraction enriched in maltose and a fraction enriched in glucose;
(d) bringing said fraction enriched with maltose into contact with a maltogenic &agr;-amylase in order to obtain a maltose-rich syrup.
The invention also proposes a process for the preparation of a maltose-rich syrup comprising the successive steps consisting in:
(a) carrying out liquefaction of a starch milk;
(b) carrying out saccharification of the liquefied starch milk in the presence of a &bgr;-amylase;
(c) carrying out molecular sieving of the liquefied and saccharified starch milk so as to collect a fraction enriched in maltose and a fraction enriched in glucose;
(d) bringing said fraction enriched in maltose into contact with a maltogenic &agr;-amylase and at least one debranching enzyme selected from the group comprising pullulanases and isoamylases in order to obtain a maltose-rich syrup.
The process for the preparation of a maltose syrup which is the object of the present invention is based in fact on a simple observation which has been neglected hitherto whereby the action of a specific enzyme on a given substrate is effective only if the characteristics as such of the substrate effectively permit the action thereof.
In the present case, an effective action of maltogenic &agr;-amylase may be obtained only on a liquefied and saccharified starch milk having a particular composition, having in particular a bimodal carbohydrate spectrum, namely having, apart from a high maltose and an appreciably high oligosaccharide content, a high glucose content.
The present invention seeks therefore, to ensure that the impurities are in the form of glucose rather than in the form of oligosaccharides, and in particular maltotriose, with a molecular mass close to that of maltose.
The particular bimodal carbohydrate spectrum of the liquefied and saccharified starch milk is obtained according to the process of the invention by carrying out a molecular sieving step on the latter.
The first step of the process according to the invention is inherently known. It consists in liquefying a starch milk of any botanical origin; it may originate from wheat, corn or potato, for example.
Acid is added to this starch milk in the case of so-called acid liquefaction, or an &agr;-amylase is added in the case of enzymatic liquefaction.
In the process according to the invention, it is preferable to carry out controlled hydrolysis of the starch milk so as to obtain a liquefied starch milk with a low degree of conversion. Thus, the conditions of temperature, pH, enzyme and calcium level known to the skilled person are determined in such a way that they make it possible to obtain a DE (dextrose equivalent) of less than 10, preferably less
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