Saccharification of glucose raffinate or mother liquors

Saccharification of low DP polysaccharides of high glucose content syrups by short term contact with amyloglucosidase e.g. 1-10 hours, 1-10 AG units/gm of syrup solids, and syrup concentrations of 5-25 w/o solids in a batch saccharification, less than 30 minutes in a continuous process employing immobilized AMG. Suitable high glucose content syrups are co-products that result from fractionation of isosyrup into 50+% d.s.b. fructose syrups and from production of crystalline dextrose.

The carbohydrates available for large scale (food) use as sweetener 
materials are sucrose, glucose (or dextrose) and a glucose/fructose 
mixture known in the art as isosyrup. Sucrose, i.e. cane and beet sugar is 
the standard sweetener of commerce and to a very large extent its price 
level determines the market penetration of glucose and isosyrup into the 
sweetener market. However, price considerations may not be the controlling 
factor, as witness the usual situation wherein glucose is cheaper than 
isosyrup, and isosyrup is cheaper than sucrose yet the sweetener market 
employs more sucrose than isosyrup, and more isosyrup than glucose. 
The sweetness factor must be taken into account. Glucose is less sweet than 
sucrose. Fructose, however, is sweeter than sucrose. Unfortunately, the 
enzymatic isomerization procedures employed to convert glucose into 
isosyrup can not exceed about 45% fructose d.s.b. (dry solids basis). A 
syrup having in excess of about 50% fructose d.s.b. is required to 
overcome the sweetness factor consideration. 
An inexpensive fructose/glucose syrup with 55% fructose d.s.b., purportedly 
would have wide acceptance, in substitution for sucrose (for uses that do 
not accept the 42% fructose content isosyrup of commerce). 
Fructose contents in excess of 50% d.s.b. can be achieved by application of 
adsorptive separation techniques to isosyrup for separating the isosyrup 
into a fructose extract and a glucose raffinate. Unfortunately, the 
isosyrup of commerce contains a significant polysaccharide content, e.g. 
7%, and the bulk of the polysaccharides pass into the glucose raffinate. 
In consequence the fructose extract is quite pure, but the glucose 
raffinate contains, perforce, more polysaccharides than is usual in 
glucose syrups, and therefore is marketable only at some sort of discount 
from higher DE glucose syrups. Since economics (i.e. price of the 
sweetener) is such an important consideration to the market penetration of 
each sweetener substance, fractionation of isosyrup into a high fructose 
syrup extract must avoid any diminution in the sales value of the glucose 
raffinate co-product. 
THE INVENTION 
Briefly stated the present invention involves a multi-step process wherein 
a fructose-glucose syrup is fractionated into a fructose extract and a 
glucose/polysaccharide raffinate, and then the raffinate is saccharified. 
Optionally thereafter the raffinate is isomerized into a fructose-glucose 
syrup (i.e. isosyrup). Desirably the isomerized raffinate is added to the 
fructose extract, whereby only one product results, namely a 50+% fructose 
product which is higher in DE than the isosyrup starting material. 
An important aspect of this invention is saccharification of a glucose 
syrup containing in excess of about 50% glucose d.s.b. and about 5;l % 
di-, tri-and polysaccharides with an immobilized amyloglucosidase. One 
such a syrup is the glucose raffinate already described. Another such 
syrup arises (as a mother liquor) in the production of crystalline 
dextrose. 
RATIONALE OF THE INVENTION 
The isosyrup of commerce normally is described to the trade in terms of its 
fructose/glucose content (42% fructose) with presence of polysaccharides 
therein alluded to only incidentally in terms of its dextrose equivalent, 
e.g. DE 96. The polysaccharide content of DE 96 is about 7w/o d.s.b. 
Thus fractionation of isosyrup so as to remove fructose will raise the 
polysaccharide content of what remains behind i.e. the glucose raffinate 
in some proportion to the extract/raffinate split. Since polysaccharides 
constitute a sweetness reducing and taste impairing impurity, their 
increased concentration in the glucose raffinate constitutes a detriment 
therein. 
On the other hand, if concentration of the polysaccharide content of an 
isosyrup in a particular fraction were somehow found to be desirable, then 
their (inherent) concentration in the glucose raffinate would be an asset 
to the fructose/glucose separation system. 
In point of fact, concentration of the polysaccharides in the raffinate is 
advantageous, because an increased concentration makes the polysaccharides 
more available for saccharification to glucose. The glucose raffinate 
fraction from an isosyrup fractionation system can be saccharified into a 
glucose product of higher purity than the DE-96 glucose initially employed 
to form the isosyrup. 
According to practice of this invention an isosyrup is (adsorptively) 
fractionated into a 50+% fructose extract fraction and a 
glucose/polysaccharide raffinate fraction, and thereafter the raffinate is 
saccharified to a dextrose equivalent (DE) at least as high as the DE of 
the isosyrup starting material. 
DISCUSSION OF THE INVENTION 
In the least complex system contemplated for practice of this invention, 
namely fractionation of an isosyrup followed by saccharification of the 
glucose raffinate two high quality products result, i.e. 50+w/o fructose 
d.s.b., and a 96+DE glucose syrup. 
If only a poor market for glucose exists (even for high quality glucose), 
then the glucose syrup, can be isomerized into an isosyrup of high quality 
i.e. 96+DE for marketing purposes. 
In total practice of the present invention offers the art virtually 
complete design flexibility ranging from a two product system of good 
quality glucose or isosyrup and 50+w/o d.s.b. fructose clear through to a 
single product system for making 50+w/o d.s.b. fructose. 
A one product of 50+w/o fructose can be produced by isomerizing the 
saccharified glucose raffinate and adding this isomerizate directly to the 
fructose extract. In theory, at least, a 65% fructose d.s.b. syrup will 
result from a single pass of isosyrup through a system including: 
(1) fractionation 
(2) raffinate saccharifier 
(3) isomerizer 
If the raffinate saccharifier were eliminated, then the fructose syrup 
would be much higher in polysaccharides, e.g. 7%, and slightly lower in 
fructose, and consequently the sweetness factor would be reduced and the 
taste would remain less agreeable. 
The 55% fructose syrup alluded to above as readily marketable, can be 
obtained directly with a single pass of syrup through the system. However, 
recycling or multiple passes of raffinate through isomerization and 
fractionation can be made, and are contemplates for a one product system 
that produces a fructose syrup exceeding about 65 w/o d.s.b. 
Basically the limiting criteria imposed upon practice of this invention are 
the criteria set by the fractionation per se, yet per se the fractionation 
separation of an isosyrup into a 50+% fructose extract and a glucose 
raffinate form no part of this invention. Several modes of fractionation 
have been proposed to the art, e.g. one is the "Sorbex" system by U.O.P. 
Inc. and one is proposed by Boehringer Mannheim GmbH (see U.S. Pat. No. 
3,864,166). Suffice it here to say that fractionation of an isosyrup into 
a high fructose extract and a glucose/polysaccharide raffinate can be 
carried out by known to the art techniques and that the details of such 
fractionation form no part of this invention. 
Saccharification of dextrins into high DE syrups are well known to the art 
and enzymatic saccharification is contemplated herein using the enzymes, 
pH, and temperature long established for conversion of dextrins. However, 
a glucose/polysaccharide raffinate is not the same as a dextrin and 
saccharification procedures explicitly adapted for the 
glucose/polysaccharide raffinate is herein described. The details of the 
saccharification procedure forms part of this invention. 
Specifically the raffinate polysaccharides are low molecular weight, being 
very largely di-and tri-saccharides. In addition more than 50% glucose 
d.s.b. is present. The saccharifying enzymes available to the art to 
catalyze hydrolysis of polysaccharides into glucose are known to catalyse 
glucose dimerization into maltose and iso-maltose. Fortunately, 
saccharification proceeds quicker than the formation of isomaltose. The 
usual saccharification of dextrin commences with a low DE syrup, e.g. DE 
10-30 with little or no glucose therein, a factor which minimizes the 
glucose reversion reaction, and enhances the saccharification reaction. 
The saccharifying circumstances adapted to dextrin saccharification are 
not as well adapted for the instance of a glucose/polysaccharide raffinate 
with its high glucose concentration and DP-2,3,4 polysaccharides. 
It has been found that saccharification of a glucose/polysaccharide 
raffinate is most effective when carried out with high enzyme 
concentration, and with less concentrated syrup (vis a vis the usual 
dextrin, c.f. U.S. Pat. No. 4,017,363). Batch saccharification of a 
glucose/polysaccharide raffinate should be carried out with from 1-10 AG 
units/gm of syrup solids, for 1-10 hours and the syrup should be less than 
about 25 w/o solids, 5-25% solids is the range. The reaction temperatures 
range and pH range are the same as for saccharifying dextrins, i.e. 
55.degree.-60.degree. C., pH 4.0-5.0. 
A particularly preferred saccharifying method employs an immobilized 
Amyloglucosidase (AMG), reference being made to copending application Ser. 
No. 810,788 for disclosure of an immobilized AMG suitable for practice of 
this invention. The high AMG concentrations and short time contact period 
best suited to saccharifying a glucose/polysaccharide raffinate and like 
glucose syrups e.g. the mother liquor from dextrose crystallization 
processes. 
Continuous saccharification of a glucose-polysaccharide raffinate is 
preferably conducted at a flow rate corresponding to 1 gm of dry solids 
per 1-30 AG units per hour (i.e. a contact time of 1-30 minutes). The 
syrup concentration should be less than ca. 25 w/o (d.s.b.), 5-25 w/o 
(d.s.b.) being the preferred range. Typical temperature and pH conditions 
of the column reaction are in the range of 50.degree.-60.degree. C. and 
3.5-7.0, respectively.

Referring now to the drawing, it may be seen that fractionator 10 receives 
an iso-syrup feed from line 11 and discharges a fructose extract into line 
13, and a glucose and polysaccharide raffinate into line 17. The fructose 
content of glucose enzymatically isomerized, e.g. in isomerizer 20 into 
the isosyrup feed will not exceed about 45%, and for exemplary purposes 
commercial quality isosyrup of 42% fructose, 51.3% glucose and 6% 
polysaccharides may be considered typical of the available 
fructose/glucose syrups. 
The details of the fractionator are not illustrated. The fractionation per 
se forms no part of this invention. Several modes of fructose separation 
systems are known to the art, with at least one offered on a commercial 
basis (i.e. "Sorbex" by UOP). Suffice it then to say only that 
fractionator 10 operates on adsorption principles, and separates the feed 
stream iso-syrup into a fructose extract having more than 50% fructose 
d.s.b. The fructose content of the extract can be predetermined as desired 
(since such flexibility is one attribute of this invention), but for 
exemplary purposes will be illustrated at 55% and 80% fructose d.s.b. For 
illustrative purposes the ultimate fructose content of the syrup product 
of this invention will be 55% fructose d.s.b. 
The saccharifier 15 into which the raffinate glucose/polysaccharide stream 
flows by way of line 17 is either a batch process or a continuous 
immobilized enzyme column as has been described above and exemplified 
hereafter. In either event the saccharifier 15 is adapted to convert the 
polysaccharide content of the raffinate into glucose as quickly as is 
reasonably possible, and to do so before the enzyme catalyzed reversion of 
glucose to maltose and isomaltose becomes material. 
Flow of the saccharified raffinate from saccharifier 15 by way of line 19 
out of the system is illustrated in the drawing to show that the glucose 
may be a product of the system. However, several of the uses to which the 
saccharified raffinate may be put according to practice of this invention, 
are illustrated also. Thus the saccharified raffinate leaving saccharifier 
15 by way of line 19 may be passed to isomerizer 25 by way of line 21. 
Then after isomerization the raffinate isosyrup may be passed by way of 
line 23 for addition to the fructose extract. Since, the saccharified 
raffinate is isomerized into an iso-syrup of purity equal to or better 
than the iso-syrup heretofore offered to the trade, the syrup can be 
removed by line 27 as a product of the system. A third alternative 
illustrated in the drawing is to send to isomerizate through line 29 into 
fractionator 10. 
For further understanding of this invention conversion of a typical 
iso-syrup into 55% fructose d.s.b. will be illustrated with fractionation 
conditions (Sorbex system) productive of 55% and 80% fructose d.s.b. (The 
iso-syrup feed contained 42% fructose, 53% glucose, 1.5% 
maltose/maltulose, 1.5% isomaltose and 2% DP3+ d.s.b. 
1. 1000 pounds/hr d.s.b. of iso-syrup solids from isomerizer 20 is 
fractionated in fractionator 10 into 452 lbs/hr of an extract containing 
90% fructose and 10% glucose and 548 lbs/hr of a raffinate containing 
88.6% glucose, 2.3% fructose 2.7% maltose/maltulose, 2.7% isomaltose and 
3.7% DP3+. 
Saccharification of this raffinate in saccharifier 15 results in a glucose 
syrup containing 0.3% maltose/maltulose, 3.0% isomaltose, 0.4% DP3+, 2.3% 
fructose and 94.0% glucose, a subsequent isomerization in isomerizer 25 
produces an iso-syrup of 26.1% fructose, 70.2% glucose and 3.7% 
polysaccharides. This stream is now mixed with the extract stream 13, 
resulting in a 98 DX product of the following composition: 55% fructose, 
43% glucose and 2% polysaccharides. It is remarkable that this 55% 
fructose product is of greater purity than the isosyrup feed stream. 
If a product with a fructose content of more than about 65% is desired the 
isosyrup from isomerizer 25 is recycled by way of line 29 back into the 
fractionation. 
2. 1000 lbs/hour d.s.b. of isosyrup from isomerizer 20 is mixed with stream 
29 (1010 lbs/hour) from the raffinate isomerizer 26 before being 
fractionated into 1000 lbs/hour of a fructose extract having 80% fructose, 
17.4% glucose, 0.5% maltose/maltulose, 1.8% isomaltose and 0.3% DP3+ 
(corresponding to 98.6 DE) and 1010 lbs/hour of a glucose raffinate having 
2.3% fructose, 90.2% glucose, 2.0% maltose/maltulose, 3.0% isomaltose and 
2.5% DP3+. Saccharification of this raffinate in saccharifier 15 results 
in a glucose syrup containing 2.3% fructose, 92.7% glucose, 1.0% 
maltose/maltulose, 3.3% isomaltose and 0.7% DP3+. A subsequent 
isomerization of the raffinate to 40% fructose d.s.b. is made before this 
stream (29) is mixed with stream 11. 
For further understanding of this invention reference is now made to the 
following specific examples. 
EXAMPLE I 
Comparison between Saccharification of Raffinate By Soluble AMG and By 
Immobilized AMG 
The saccharification of a raffinate consisting of 84.3% Glucose, 2.9% 
Fructose, 9.4% maltose, 0.5% isomaltose and 2.9% maltotriose and higher 
polymers was performed in a batch operation under the following 
conditions: 20.6% w/w dry solid, 60.degree. C. and pH 4.5. The following 
experimental results were obtained. 
Table IA 
__________________________________________________________________________ 
5000 ml batch 5000 ml batch 
20 ml AMG 150 10 ml AMG 150 
Iso- Iso- 
Hours 
Monosacc 
Maltose 
malt 
DP3+ 
Monosacc 
Maltose 
malt 
DP3+ 
__________________________________________________________________________ 
0 87.2 9.4 0.5 
2.9 87.2 9.4 0.5 
2.9 
0.17 91.8 4.9 0.5 
2.8 91.0 6.1 0.5 
2.4 
0.50 95.6 1.2 0.6 
2.6 95.9 2.3 0.5 
1.3 
1.00 97.1 0.6 0.6 
1.7 96.6 1.2 0.6 
1.6 
2.00 98.3 0.6 0.7 
0.3 97.5 0.8 0.7 
0.9 
5.00 98.5 0.1 0.9 
0.4 97.7 1.1 0.9 
0.3 
23.17 
93.0 0.0 4.7 
2.4 95.9 0.0 3.5 
0.7 
__________________________________________________________________________ 
A raffinate with the same composition was then saccharified in a fixed bed 
column operation. 
The IAMG was produced according to example 2 in patent application Serial 
No. 810,788 filed June 28, 1977. The following conditions were applied: 
20.6 w/w% dry solid, 55.degree. C. and pH 4.5. 
The following experimental results were obtained: 
______________________________________ 
Product Composition, % 
Flow Iso- 
Space Time 
ml/hr DX Maltose 
Maltose 
DP3+ 
______________________________________ 
4.7 minutes 
181 96.4% 1.2 0.6 1.8 
7.5 minutes 
113 97.2% 1.0 0.6 1.2 
10.0 minutes 
85 97.8% 0.8 0.8 0.6 
20.0 minutes 
43 96.9% 0.7 2.0 0.4 
37.5 minutes 
23 93.6% 1.3 4.0 1.2 
______________________________________ 
Inlet raffinate composition: as above 
column size: 2.5 cm(d) by 40 cm(h) 
Amount of IAMG: 5g 
The product composition was determined by HPLC. 
EXAMPLE II 
Long Time Saccharification of Raffinate by IAMG 
The saccharification of a raffinate consisting of 84.4% Glucose, 2.8% 
Fructose, 8.9% maltose, 1.0% iso-maltose and 2.9% maltotriose and higher 
polymers was carried out in a fixed fed column of IAMG under the following 
conditions: 
5 g IAMG (as in example I) 
Column 2.5 cm(d), 40 cm(h) 
20.6 w/w% dry solid 
55.degree. C., pH 4.5 
Constant flow rate 175 ml/hour, contact time 5 min. 
______________________________________ 
Time Product Composition 
(days) Monosacch. Maltose Isomaltose 
DP3+ 
______________________________________ 
1 97.4% 0.6% 1.2% 0.8% 
3 97.0% 1.0% 1.1% 0.9% 
6 96.0% 2.0% 1.2% 0.8% 
10 95.7% 1.5% 1.3% 1.5% 
15 94.5% 2.7% 1.1% 1.7% 
20 93.9% 2.9% 1.2% 2.0% 
27 93.5% 2.6% 1.3% 2.6% 
30 93..0% 3.0% 1.2% 2.8% 
______________________________________ 
EXAMPLE III 
Influence of Temperature on IAMG activity and Stability 
Conditions as in Example II 
______________________________________ 
Days 
Initial Product Composition to reach 
Iso- 93.3% 
Tem- Mono- Mal- mal- Mono- 
perature 
sacch. tose tose DP3+ sacch. 
______________________________________ 
55.degree. C. 
97.4% 0.6% 1.2% 0.8% 28 
60.degree. C. 
97.5% 0.6% 1.2% 0.7% 9 
65.degree. C. 
97.9% 0.7% 1.1% 0.8% 6 
______________________________________ 
EXAMPLE IV 
Comparison Between Saccharification of a Mother Liquor With a High 
Isomaltose Content By Soluble AMG and By Immobilized AMG 
Conditions as in Example I, but Mother Liquor composition: Fructose 1.1%, 
Glucose 65.3%, 13.4% Maltose, 10.0% Isomaltose, 2.5% DP3 and 7.7% DP4+. 
Saccharification with Soluble AMG: 
______________________________________ 
5000 ml Batch 
20 ml AMG 150 
Hours Monosacc Maltose Isomalt 
DP3+ 
______________________________________ 
0 66.4% 13.4% 10.0% 10.2% 
0.17 69.3% 11.7% 10.3% 8.7% 
0.50 72.1% 10.4% 10.5% 7.0% 
1.00 76.7% 6.5% 10.8% 6.0% 
2.00 80.1% 3.9% 11.2% 4.8% 
5.00 82.0% 2.3% 11.3% 4.4% 
23.17 84.5% 0.3% 13.2% 2.0% 
______________________________________ 
Saccharification with IAMG: 
______________________________________ 
Product Composition 
Space Time 
Flow Monosacc Maltose 
Isomalt 
DP3+ 
______________________________________ 
4.7 min 
180 ml/h 81.6% 3.0% 10.2% 5.2% 
7.5 min 
112 ml/h 82.8% 2.3% 10.4% 4.5% 
10.0 min 
95 ml/h 84.0% 1.8% 10.5% 3.7% 
20.0 min 
45 ml/h 82.0% 1.1% 11.0% 4.6% 
______________________________________ 
EXAMPLE V 
Comparison between saccharification of raffinate by soluble AMG and by 
immobilized AMG 
The saccharification of a raffinate consisting of 83.9% glucose, 3.3% 
fructose, 6.2% maltose, 3.1% isomaltose and 3.4% maltotriose and higher 
polymers was performed in a batch operation under the following 
conditions: 20.5% w/w dry solid, 60.degree. C. and pH 4.5. The following 
experimental results were obtained. 
______________________________________ 
5000 ml batch, 20 ml AMG 150 
Hours Monosacch. Maltose Isomaltose 
DP3+ 
______________________________________ 
0 87.3 6.2 3.1 3.4 
0.17 92.0 2.5 3.1 2.4 
0.33 92.8 2.0 3.2 2.0 
0.50 93.9 1.4 3.2 1.5 
1 94.9 1.1 3.4 0.6 
2 94.8 0.9 3.5 0.8 
22 91.8 0.1 6.0 2.1 
______________________________________ 
A raffinate with the same composition was then saccharified in a fixed bed 
column operation. 
The IAMG was produced according to example 2 in patent application Serial 
No. 810,788 filed June 28, 1977. The following conditions were applied: 
20.5 w/w% dry solid, 55.degree. C. and pH 4.5. 
The following experimental results were obtained: 
______________________________________ 
Space time 
Flow Product composition, % 
minutes ml/hour DX Maltose 
Isomaltose 
DP3+ 
______________________________________ 
5.6 170 94.2 1.3 3.2 1.3 
8.2 117 94.7 1.1 3.2 1.0 
13.5 71 95.1 0.9 3.4 0.6 
18.6 52 95.3 0.7 3.5 0.5 
25.6 37 95.1 0.6 3.6 0.7 
______________________________________ 
Inlet raffinate composition: as above 
Column size: 2.5 cm(d) by 40 cm(h) 
Amount of IAMG: 5g? 
The product composition was determined by HPLC. 
EXAMPLE VI 
Long Time Saccharification of Raffinate by IAMG 
The saccharification of a raffinate consisting of 83.9% glucose, 3.3% 
fructose, 6.2% maltose, 3.1% isomaltose and 3.4% maltotriose and higher 
polymers was performed in a fixed bed column operation by use of IAMG 
under the following conditions: 
5 g IAMG (as in example I) 
Column 2.5 cm (d), 40 cm (h) 
20.6 w/w% dry solid 
55.degree. C., pH 4.5 
Constant flow rate 175 ml/hour, contact time 5 min. 
______________________________________ 
Time Product composition, % 
(days) Monosacch. Maltose Isomaltose 
DP3+ 
______________________________________ 
1 94.5 1.0 3.3 1.2 
3 94.0 1.3 3.4 1.3 
6 93.8 1.5 3.2 1.5 
9 93.3 1.7 3.3 1.7 
11 92.9 2.0 3.3 1.8 
______________________________________