Note: Descriptions are shown in the official language in which they were submitted.
~5~3
7 DETAILED DESCRIPTION
8 It is known that heteropolysaccharides can be
9 produced by certain microorganisms. Some of such hetero-
polysaccharides function as hydrophilic colloids and
11 because of their viscosity properties and rheology have
12 been used as thickenins agents for aqueous systems. Of --
13 particular interest are such heteropolysaccharides or
14 biogums as xanthan gum, S-7 gum and S-10 gum. Details
lS of the preparation of these gums are known and are described
16 in issued patents. The preparation of xanthan gum is
17 described, for exa~ple in U.S. patents 3,020,207 and
18 3,256,271; the preparation of S-7 gum is described, for
~ ;'
~ ~ .
K-1963
example, in U.S. patent 3,960,832; and the preparation of
2 S-10 gum is described, for example, in U.S. patent
3 3,933,788.
4 Xanthan gum is a high molecular weight hetero-
5 polysaccharide with a molecular weight of ~106. It con-
6 tains D-glucose, D-mannose, and D-glucuronate in the molar
7 ratio of 2.8:2.0:2Ø It is partially acetylated with
8 about 4.7% acetyl. It also contains about 3% pyruvate
9 attached to a single unit D-mannopyranosyl side chain as
10 a ketal.
11 S-7 gum is a high moLecular weight heteropoly-
12 saccharide whose carbohydrate portion consists of about
13 73% glucose, about 16~ rhamnose, and about 11~ guluronic
14 acid. It has an acetyl content of 8-10%. It is soluble
15 in water and slightly soluble in lower alkanols and
16 acetone.
17 S-10 gum is a high molecular weight heteropoly-
18 saccharide containins about 3% protein and about 97~
19 carbohydrate. The carbohydrate portion contains about
20 39% glucose, about 29% ~alactose, about 13~ fucose, and
21 about 19% of glucuronic acid. It is soluble in water
22 an~ substantially insoluble in dimethylsulfoxide.
23 In the case of xanthan gum, at the completion of
24 the fermentation when the yield of xanthan gum is at about
25 its maximum the fermentation process is terminated by
26 chemical or physical treatment which pasteurizes the beer.
27 The xanthan gum is then recovered in conventional manner,
28 e.g., precipitated by addins isopropyl alcohol, dried and
29 milled.
;
K-1963
1 It has now been found that the ~anthan gum pro-
2 duced by such a fermentation process has impro~ed dis-
3 persibility in aqueous systems if the beer is heated in
4 the presence of a dialdehyde at a p~ of about 7 or below,
preferably at a pH of about 4.5 to about 7. The dialdehyde
6 is present during this heat treatment in an amount of at
7 least about 0.5% based on the weight of the dry xanthan
8 gum in the beer. While amounts of dialdehyde up to about
9 15% by weisht or the dry xanthan gum in the beer may be
used, in seneral amounts greater than about 3~ do not confer
11 any discernible improvement and are therefore uneconomic.
12 Similar results are obtained when an S-7 or S-10 gum
13 fermentation beer is substituted for the xanthan gum beer.
14 The aldehyde may be an aliphatic dialdehyde of
from 2 up to about 8 carbon atoms, e.g., glyoxal, malon-
16 aldeh~de, succinaldehyde, glutaraldehyde, adipinaldehyae
17 or octandialdehyde, or polyglyoxal, an oligomeric form
18 of glyoxalhydrates having rom 5 to 10 glyoxalhydrate
19 repeating units. Glyoxal is preferred.
~he dialdehyde is added to the beer at about the
21 completion of the fermentation process, preferably with
22 agitation to obtain uni-orm distribution of the dialdehyde.
23 The beer is then heated to a temperature of from about
24 70C to about 100C for a time sufficient to improve the
dispersibility of the recovered biogum. In seneral, this
26 ta~es at least about 2 minutes, typically from about 2 to
27 about 5 minutes. ~nile longer heatins times may be em-
28 ployed, no additional improvement is seen in dispersibility
29 after about 5 minutes of heating.
K-1363
55:~
1 ~eating in the presence of a dialdehyde at a
2 pH below about 7 to obtain improved disperslbility
3 according to the present invention is most conveniently
4 and economically carried out by combining the dialdehyde
S treatment with pasteurization by heating. In this way
6 no additional time or heating expense is required for the
7 dialdehyde treatment beyond the cost of the dialdehyde
8 itself. ~ile the foreyoing description has described
9 the present invention with reference to a fermentation
beer, it will be obvious to those skilled in the art that
11 the invention is not limited to fermentation beers but
12 that it is applicable to any aqueous solution of a biogum.
13 The following examples illustrate the present
14 invention without, however, limiting the same thereto.
-- 4
~ 196:
, . .
S~3
1 EXA~PLE 1
2 To five aliquots of unpasteurized xanthan gum
3 rermentation beer at p~ 6.5 each weighing 1000 g, there
4 is added 80% glyoxal powder at levels of 1~, 2%l 5%, 10%
and 15%, respectively. After stirring for 15 minutes at
6 about 30C, the beer samples are heated as rapidly as -,
7 possible to about 95C, held for 5 minutes at this temper-
8 ature, and then cooled as rapidly as possible to room
9 temperature. Each sample is treated with isopropanol to
precipitate the xanthan gum. The precipitates are dried
11 in a steam dryer at 150F (65.5C) and milled through a
12 60-mesh (U.S. Standard) screen.
13 Three grams of xanthan gum from each aliquot
14 are sprinkled evenly over the surface of 297 ml distilled
water contained in a 400 ml beaker with a stirrer in
16 place. After 30 seconds the stirrer, which rotates at
17 about 800 rpm, is switched on for one minute. The stirri~g
18 is then stopped and the dispersibility is rated visually.
19 The following results are obtained.
20 Aliquot Glyoxal Level Dispersibllity
21 Control Poor
22 1 1 % Good
23 2 2 ~ Good
24 3 5 % Excellent
4 10 % Excellent
26 5 15 % Excellent
~' ' ~ ' ' `
K-19h3
5~3
1 EXAMPLE 2
2 Aliquots of two pasteurized xanthan gum
3 ~ermentation beers weighing 1000 g each are adjusted
4 to p~ 5.0 and 6.0, respectively, and treated with 80~
glyoxal powder at levels of 0.5%, 1.0~ and 1.5% based
6 on the weight of the dry gum in the beer. After stirring
7 for 15 minutes at about 30C, the aliquots are heated
8 as rapidly as possible to 95C, held for 5 minutes at
9 this temperature, and then cooled to room temparature.
The samples are precipitated in isopropanol, dried in a
11 steam dryer at about 150F (65.5C) and milled through a
12 60-mesh (U.S. Standard) screen.
13 Three grams of xanthan gum from each aliquot are
14 sprinkled evenly over the sur~ace of 297 ml distilled
water contained in a 400 ml beaker with a stirrer in place.
16 After 30 seconds the stirrer, which rotates at about 300
17 rpm, is switched on for one minute. The stirring is
18 then stopped and the dispersibility is rated visually.
19 The following results are obtained:
pH Dispers-
21 AliquOt ~ Before Adiustment Glyoxal Level ibility
223 Control 5 0 6.8 0 Poor
24 1 5.0 6.8 0.5% Fair
25 2 5.0 6.8 1.0~ Good
26 3 5.0 6.8 1.5% Good
27 control
28 B 6.0 7.2 0 Poor
29 4 6.0 7.2 0.5~ Fair
30 5 6.0 7.2 1.0~ Good
31 6 6.0 7.2 1.5% Good
-- 6
~, :
-
K-1963
3~ 3
1 EX~PLE 3
2 Samples of unpasteurized xanthan gum fer~en-
3 tation beer are adjusted to either pH 5.0 or 6.5. Aliquots,
4 1000 g, of these samples are treated with 40% glyoxal
liquid at levels of 0.5%~ 1.0~ and 2.0% based on the weight
6 Of the dry gum in the beer for the pH 5 aliquots, and
7 with 5.0~ and 10.0% levels based on the level o the dry
8 yum in the beer for the pH 6.5 aliquots. After stirring
9 for 15 minutes at about 30C, the aliquots are heated as
10 rapidly as possible to about 95C, held for 5 minutes at
11 this temperature, and then cooled as rapidly as possible
12 to room temperature. The aliquots are treated with iso-
13 propanol to precipitate the xanthan gum, dried in the steam
14 dryer at about 150F (65.5C) and milled through a 60-mesh
(U.S. Standard) screen. Three grams of the dried gum ~rom
16 each aliquot are sprinkled evenly over the sur~ace of
17 297 ml distilled water contained in a 400 ml beaker with a
18 stirrer in place. A ter 30 seconds the stirrer, which
19 rotates at about 800 rpm, is switched on for one minute.
20 The stirring is then stopped and the solution is screened
21 through a 20-mesh (U.S. Standard) screen, and the wet
22 material remaining on the screen is weiyhed. The following
23 results are obtained:
24 Aliquot ~ Gl~oxal Level Weight of Material on Screen
25 control
26 A 5.0 0 22.3g
27 1 5.0 0.5% 8.6g
28 2 5.0 1.0% 1.6g
29 3 5.0 1.5% 0 g
4 5.0 2.0% 0 g
31 Control
32 B 6.5 0 22.3g
33 5 6.5 5.0% 0
34 6 6.5 10.0% 0 g
g-1963
1 EXAMPLE 4
2 The procedure of Example 1 is repeated using
3 1000 g aliquots of S-7 beer adjusted to pH 6.0 and treated
4 with 80% glyoxal powder at levels of 0.25%, 0.5~, 1.0%
and 2.0%. The following results are obtained:
6 All~uot Glyoxal LevelDispersibility
7 Control 0 Poor
8 1 0.25% Poor
9 2 0.5 ~ Poor
3 1~0% Fair
11 4 2.0% Good
12
13 EXAMPLE 5
14 The procedure of Example 1 is repeated using
15 1000 g aliquots of S-10 beer adjusted to pH 6.0 and
16 treated with 80% glyoxal powder at levels of 0.25~,
17 0.5~, 1.0~ and Z.0~. The following results are obtained:
18 Ali~uot Glyoxal_LevelDispersi~ility
19 Control 0 Poor
20 1 0.25% Fair
21 2 0.5 % Good
22 3 1.0 % Good
23 4 2.0 % Excellent
