Chewing gum with improved storage qualities

This invention relates to a chewing gum composition which comprises gum base, sweetener, flavor and xylitol. The xylitol is contained in the gum in amounts less than 50% by weight of the total gum composition, the xylitol being effective to extend the storage stability of the gum.

BACKGROUND OF THE INVENTION 
Chewing gums are generally comprised of chewing gum base such as chicle, 
its substitutes, mixtures thereof and the like. Incorporated within this 
gum base may be plasticizers or softeners to improve the consistency and 
texture of the gum, flavors and sweetening agents such as corn syrup or 
for sugarless gums, artificial sweeteners. 
All commercially available gums are classified as either "sugar" or 
"sugarless" confections. A typical sugar gum is Wrigley's Chewing Gum 
manufactured by the William Wrigley, Jr., Company, Chicago, Illinois. An 
example of a sugarless chewing gum is Trident, manufactured by the 
Warner-Lambert Company, Morris Plains, New Jersey. These gums have a 
tendency to become brittle on storage at low relative humidities (below 
about 55% RH) which is the condition that prevails in many locations where 
gum is sold. The development of brittleness which detracts from the good 
chewing quality of the gum is associated with loss of moisture to the 
atmosphere. Chewing gum is typically manufactured and packaged in a 
controlled environment of about 70.degree. F. at about 57% relative 
humidity. Under these conditions the gum is in equilibration with the 
atmosphere, that is, the gum neither gains nor loses moisture. Gum 
wrappers or packaging represent a substantial portion of the cost of 
manufacture in the processing of chewing gum. Particularly, each stick of 
gum is usually covered by at least three or four separate layers of 
wrapping or packaging material before it is put in the stream of commerce. 
Such packaging slows down but does not alleviate the loss of moisture 
unless expensive and perfect (i.e., free from pinholes, a condition which 
is all but impossible to achieve in practice) packaging materials are 
used. 
It would, therefore, be highly desirable if a chewing gum composition could 
be devised which would not become brittle upon storage at low relative 
humidities. 
SUMMARY OF THE INVENTION 
This invention relates to a sweetened chewing gum composition which 
comprises gum base, sweetener and flavor to which xylitol is added in 
amounts less than 50% by weight of the gum composition which xylitol is 
effective to extend the storage stability of the gum. Additionally, such a 
gum generally exhibits greater softness, flexibility and extensibility and 
freedom from cracking when bent compared to commercially available gums. 
DETAILED DESCRIPTION OF THE INVENTION 
The chewing gums of this invention comprise a gum base, sweeteners, flavors 
and an amount of xylitol which is less than 50% of the total gum 
composition by weight which xylitol is effective to extend the storage 
qualities of the gum. .Iadd.Amounts of xylitol less than 10% by weight of 
the total gum composition are preferred and, as exemplified, 1 to 3.2% by 
weight. .Iaddend. 
The gum base may be any chewable, substantially water insoluble base such 
as chicle and substitutes thereof, guttagkay, sorva, jelutong, synthetic 
polymers such as polyvinyl acetate, synthetic resins, rubbers and the like 
and mixtures of these materials. The amount of gum base employed may vary 
widely depending on the type base used and other ingredients making up the 
final gum product and other like factors. Generally, however, it has been 
found that anywhere from 15 to about 40% by weight of the final gum 
composition may be used and preferably from about 20 to about 30%. 
Plasticizers or softeners such as lanolin, propylene glycol, glycerol and 
the like and mixtures thereof may optionally be incorporated within the 
gum base to achieve a desired texture and consistency. 
Generally the flavors employed in flavored chewing gums may be the 
essential oils or synthetic flavors or mixtures of these. Flavors such as 
wintergreen, spearmint, peppermint, birch, anise, fruit flavors and the 
like may be used satisfactorily with the variety of gum bases. The amount 
of flavoring material is normally a matter of preference but may be 
subject to the consideration of such factors as type of flavor used, and 
the type base used and the like. Generally, flavoring material accounts 
for about 1% by weight of the total gum composition. 
In order to obtain a sweetened gum, the remaining portion of the gum 
composition is generally a sweetener such as sugar or for sugarless gums a 
sugar substitute. By sugar we mean sucrose, dextrose, corn syrup solids 
(their substitutes) and the like and mixtures thereof. Sugar substitutes 
may be any artificial sweetening agent used in sugarless chewing gum such 
as mannitol, sorbitol, saccharin, cyclamate, dipeptide sweeteners such as 
described in U.S. Pat. No. 3,642,491, especially 
L-aspartyl-L-phenylalanine methyl ester, and dihydrochalcone as described 
in U.S. Pat. No. 3,857,962 or mixtures of these. Additionally, an amount 
of sweet or nonsweet bulking agents may be included in the gum 
composition. 
Xylitol is a pentahydric alcohol which is prepared most commonly by the 
hydrolysis of xylan (a common constituent of wood, corncobs and oilseed 
hulls) to form xylose followed by the reduction of xylose to xylitol by 
hydrogenation under pressure in the presence of a nickel catalyst. Xylitol 
appears as a crystalline compound which possesses a sweetness level of 
about 90% that of sucrose and xylitol is metabolized in the body to 
glycogen by way of the pentose-phosphate half way and is thus safely 
consumed by diabetics. 
U.S. Pat. No. 3,899,593, issued Aug. 12, 1975, discloses sugarless chewing 
gum containing a major amount of xylitol, that is 50 to 80% by weight of 
the total gum composition is xylitol. Such a gum presents a pleasant 
cooling effect in the mouth. Belgium Pat. BE No. 755,115 (U.S. counterpart 
Pat. No. 3,914,434, issued Oct. 22, 1975) discloses the use of xylitol as 
a non-cariogenic sugar substitute. 
It has now been surprisingly found that xylitol, when used in amounts less 
than 50% by weight of the total gum composition, is effective to extend 
the storage stability of the gum. By this we mean it enables the gum to 
retain more moisture when stored at low relative humidities and the gum 
exhibits greater softness, flexibility and freedom from cracking when 
bent. It is believed that the water binding properties of xylitol and/or 
the effect of xylitol on the crystalline structure of the gum composition 
are responsible for these effects. 
Commercial gums are plagued by the problem of staling and the development 
of brittleness during storage. The growth of these undesirable qualities 
is accelerated during conditions of low relative humidity, i.e., below 
about 55%. This invention eliminates or minimizes these problems in sugar 
and sugarless gums. Thus, the freshness of the chewing gum can be 
preserved for long periods of time and/or necessity of extensive 
protective wrapping can be greatly reduced.

The following examples and levels of xylitol are intended to be 
illustrative only of a few of the numerous embodiments of this discovery. 
Variations in the gum compositions and preparations, other sweetening 
systems and the like are believed ascertainable to those skilled in the 
art without departing from the scope and spirit of this invention. 
EXAMPLE I 
A commercial formula of sugar-containing chewing gum was prepared 
containing different levels of xylitol substituted for part of sucrose. 
The resulting gum was equilibrated, without package protection, at 
different relative humidities for 18 days. Xylitol-containing gum lost 
less % moisture than the control at low RH's as exemplified by the 
following data: 
______________________________________ 
0 1.0 3.2 % Xylitol 
______________________________________ 
23% RH -0.63 -0.60 -0.41 
43% -0.43 -0.30 -0.10 
57% +0.20 +0.47 +0.90 
75% +2.88 +3.63 +4.60 
______________________________________ 
The xylitol containing gum was also more extensible and more bendable and 
less brittle following storage at low RH's as shown by the data in the 
following table. 
__________________________________________________________________________ 
Effect of xylitol addition on flexibility 
of sugar containing stick chewing gum 
% xylitol 
0 1.0 3.2% 
%RH 23 43 57 75 
23 43 57 75 23 
43 57 75 
__________________________________________________________________________ 
Tensile testing 
tensile yield (lbs.) 
7.5 4.6 
1.5 
0.4 
4.6 
1.5 
0.7 
0.2 
3.3 
1.5 
0.8 
0.3 
extensibility (mm) 
2.2 10.8 
11.8 
8.1 
4.8 
12.9 
16.0 
11.3 
6.7 
10.9 
10.6 
9.8 
Sensory bending 
bending angle (.degree.) 
124 37 0 0 39 0 0 0 0 0 0 0 
before cracking 
__________________________________________________________________________ 
EXAMPLE II 
A commercial formula sugarless chewing gum was prepared with xylitol 
substituted for part of sorbitol. The xylitol-containing gum lost less % 
moisture than the control at low RH's as exemplified by the following 
data: 
______________________________________ 
0 5.8 % xylitol 
______________________________________ 
23% RH -3.0 -2.4 
43 -2.7 -1.8 
57 -1.9 -0.1 
75 +1.5 +2.1 
______________________________________ 
The following shows that, similarly to the sucrose-containing gum of 
Example I, xylitol made the sugarless gum more extensible and more 
bendable and less brittle following storage at low RH's. 
______________________________________ 
Effect of xylitol addition on flexibility 
of sugarless stick chewing gum 
% xylitol 0 5.8 
& RH 23 43 57 75 23 43 57 75 
______________________________________ 
Tensile testing 
tensile yield (lbs.) 
6.1 5.5 4.7 1.5 4.8 3.5 1.9 0.2 
extensibility (mm) 
3.4 4.2 5.8 6.5 3.8 6.0 8.0 7.3 
Sensory bending 
bending angle (.degree.) 
63 61 5 0 15 0 0 0 
before cracking 
______________________________________ 
In the preceding examples an Instron Table Model TM was used with the CT 
Tensile Load Cell. A single stick of chewing gum, of the dimensions 73 
mm.times.18 mm.times.1.6 mm, was gripped at both ends and stretched at the 
rate of 1 inch per minute. Tensile yield and extensibility were recorded. 
Tensile yield (lbs.) was defined as the force required to rupture the 
sample. It was the maximum force recorded on the tensile curve. 
Extensibility (mm) was defined as the distance that the sample could be 
stretched before rupture.