Smoking articles

A smoking article which comprises tobacco treated with a high loading level of humectant and which has been expanded by a high level expansion process to produce expanded tobacco having a humectant loading level in the range of 4% to 15%. The particulate matter, water, nicotine and humectant free (PMWNHF) to nicotine delivery ratio of smoking articles according to the invention and smoked under standard machine smoking conditions is not more than 8 to 1.

FIELD OF THE INVENTION 
The invention the subject of this application relates to cigarettes and 
similar smoking articles. 
SUMMARY OF THE INVENTION 
It is an object of the subject invention to provide a cigarette which is of 
a low tar delivery but which is sensorily acceptable to the smoker. 
The subject invention provides a smoking article comprising a tobacco rod, 
which rod comprises cut tobacco and a paper wrapper circumscribing said 
tobacco, a major portion at least of said tobacco having been treated with 
a humectant to provide a loading level of said humectant of 4% to 15% by 
weight. Suitably, the loading level of the humectant on the tobacco is not 
less than 5% and does not exceed 12%. More suitably, the loading level is 
in the range of 7-10%, 9% for example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
The humectant is suitably one or more of glycerol, propylene glycol, 
sorbitol and diethylene glycol. 
Advantageously, the humectant is applied to the tobacco prior to the 
tobacco being subjected to an expansion process. The loading level of the 
humectant on the tobacco prior to expansion may be in a range of about 5% 
to about 20% in order to result in a post expansion level of 4% to 15%. 
We have found that if the humectant is applied to the tobacco before rather 
than after the tobacco is subjected to the expansion process, a reduction 
in tobacco strand length during the process is avoided. Further advantages 
of applying the humectant prior to expansion reside in the avoidance of an 
undesirably high equilibrium moisture content post expansion and the 
avoidance of a reduction in the filling power of the expanded tobacco. 
Suitably, the humectant is applied to the tobacco by being sprayed thereon, 
advantageously in aqueous solution. 
The humectant should, before the tobacco is subjected to the expansion 
process, be distributed of the tobacco with a significant degree of 
uniformity, which objective may be furthered by tumbling the tobacco 
and/or allowing the tobacco to stand in bulk for a sufficient time after 
the application of the humectant. 
Tobacco of smoking articles according to the subject invention which is to 
be subjected to an expansion process is suitably pre-conditioned to a 
moisture content in a range of 22% to 30% and preferably to a moisture 
content in a range of 26% to 30%. 
Tobacco of smoking articles according to the subject invention which is 
subjected to an expansion process may be lamina and/or stem tobacco. The 
expanded tobacco advantageously comprises a lamina tobacco the product of 
a tobacco expansion process which is effective to provide a high degree of 
expansion in tobacco subjected to the process. High expansion processes 
are disclosed, for example, in the specification of Reissue U.S. Pat. No. 
30,693 and in United Kingdom Patent Specifications Nos. 1,570,270 and 2 
160 408A. By use of high expansion processes, tobacco expansion values, in 
terms of filling value increase, of from about, typically, 75% and even up 
to about 125% may be obtained. Tobacco which has been subjected to a high 
expansion process may have a bulk density of, for example, from about 100 
mg/cc to about 200 mg/cc, and preferably not less than 150 mg/cc, as 
measured using a Borgwaldt Densimeter. 
A minor proportion of the smoking material of smoking articles according to 
the subject invention may take the form of reconstituted tobacco and/or 
tobacco substitute material. Preferably though, the smoking material 
should be wholly natural cut tobacco. It is also preferable that the whole 
or a substantial proportion of the cut tobacco of smoking articles 
according to the subject invention should be expanded tobacco and that the 
whole of this expanded tobacco should have been treated with humectant 
prior to being expanded. Suitably, at least 65% of the tobacco is treated 
expanded tobacco, and more suitably 70% is treated expanded tobacco. 
The weight of the smoking material in a cigarette according to the subject 
invention is suitably in a range of 500 to 800 mg. 
Suitably, the packing density of the smoking material of smoking articles 
according to the subject invention does not exceed 210 mg/cc. 
It is to be observed that when measurement is made of the PMWNF delivery of 
a smoking article according to the subject invention, the value obtained 
includes a proportion of the humectant. It may thus be of interest to 
express particulate matter delivery on a water, nicotine and humectant 
free basis (PMWNHF). Preferably, the PMWNHF to nicotine delivery ratio of 
smoking articles according to the subject invention is not more than 8 to 
1 and is preferably in the region of 6 to 1, and more preferably in the 
region of about 5 to 1. 
The humectant in the mainstream smoke of cigarettes according to the 
subject invention, as measured under standard machine smoking conditions, 
preferably forms not less than 15%, and more preferably not less than 20%, 
of the mainstream PMWNF. Yet more preferably the mainstream smoke 
humectant forms approximately 25% of the mainstream PMWNF. Suitably, the 
mainstream smoke humectant may also be in the range 24% to 26%, 24% for 
example. 
A burn retardant may be used in smoking articles in accordance with the 
subject invention. The burn retardant may be, for example, magnesium 
chloride, sodium chloride, ammonium sulphate, ammonium lactate, or 
mixtures thereof, applied to the smoking material. 
According to a further aspect thereof, the subject invention provides a 
tobacco treatment comprising the application of a humectant to tobacco 
and, subsequent to said application, the expanding of said tobacco, the 
application level of said humectants to said tobacco before the expansion 
step being such that the loading level of said humectant after said 
tobacco has been expanded is in a range of 4% to 15% by weight. 
In order to further the understanding of the subject invention, examples 
according thereto will now be described. 
EXAMPLE I 
To a cut tobacco blend comprising 20% water treated stem, 40% burley 
tobacco lamina and 40% flue cured tobacco lamina there was added glycerol 
at a 10% loading level and magnesium chloride at a 1% loading level. The 
blend was conditioned to 25% moisture content, the blend being thereafter 
subjected to a high level expansion process. The glycerol loading on the 
expanded tobacco was about 6%. 
Using the thus obtained expanded tobacco, 24.75 mm circumference cigarettes 
were made. Each cigarette comprised a 64 mm long tobacco rod consisting of 
100% of the expanded tobacco and of wrapper of a standard commercial 
cigarette paper. The packing density of the tobacco in the tobacco rods 
was about 145 mg/cc. To each of the tobacco rods there was attached, by a 
tipping wrapper, a 20 mm long cellulose acetate filter plug. The 
cigarettes were laser ventilated at the filters to provide a ventilation 
value of 55%. 
These cigarettes were smoked under standard (Coresta) machine smoking 
conditions according to which a 35 cm.sup.3 puff of two seconds duration 
is taken every minute and were found to yield mainstream smoke component 
deliveries as follows. 
______________________________________ 
Component Delivery (mg) 
______________________________________ 
TPM 5.88 
Nicotine 0.63 
PMWNF 4.37 
Glycerol 1.35 
PMWNHF 3.02 
______________________________________ 
It is thus to be observed that the PMWNHF to nicotine ratio was 4.8. It may 
also be observed that the glycerol delivery represented 31% of the PMWNF 
delivery. 
It was found that when smoked under Coresta machine smoking conditions, a 
commercially available cigarette, Benson & Hedges Ultra (Trade Mark), of 
similar delivery, i.e. 5.57 mg TPM, had a mainstream glycerol delivery of 
0.44 mg, this representing 9.4 per cent of the PMWNF delivery. The PMWNHF 
to nicotine ratio of the Ultra cigarettes was 9.9. 
In sensory panel smoking tests it was found that the above detailed 
cigarettes according to the subject invention exhibited sensory features 
superior to those of the Ultra cigarettes. 
EXAMPLE II 
To a first cut tobacco blend comprising 65% flue cured lamina and 35% 
burley lamina was added glycerol at a 6% loading level and ammonium 
lactate at a 2% loading level. The blend was conditioned to a 30% moisture 
content, the blend being thereafter subjected to the high level DIET 
expansion process. The glycerol loading level on the expanded tobacco was 
4.4%. 
A second cut tobacco blend comprised 50% burley lamina and 50% sun cured 
oriental lamina. The second blend was not subjected to an expansion 
process. 
The first and second blends were combined in the proportions 70% first to 
30% second and to the thus obtained combined blend was added propylene 
glycol at a 1.5% loading level. Thus the total loading level of humectant, 
glycerol plus propylene glycol, was 4.6%. 
Using the tobacco of the combined . blend 24.75 mm circumference cigarettes 
were made. Each cigarette comprised a 59 mm long tobacco rod and a 
standard commercial cigarette paper. The packing density of the tobacco in 
the rods was 190 mg/cc. To each of the rods there was attached a 25 mm 
long dual filter comprising a 7 mm long section of crimped paper and an 18 
mm long section of cellulose acetate filtration material. The cigarettes 
were laser ventilated at the cellulose acetate sections of the filters to 
provide a ventilation of 60%. 
When smoked under standard machine smoking conditions, mainstream smoke 
component deliveries were found to be as follows: 
______________________________________ 
Component Delivery (mg) 
______________________________________ 
TPM 6.79 
Nicotine 0.84 
PMWNF 5.43 
Glycerol 1.00 
Propylene glycol 
0.28 
PMWNHF 4.15 
______________________________________ 
Thus the PMWNHF to nicotine ratio was 4.9 and humectant represented 24% of 
the PMWNF delivery. 
A commercially available cigarette of similar delivery, namely Camel Lights 
(Trade Mark), was found to have a mainstream glycerol delivery of 0.39 mg, 
this representing 8% of the PMWNF delivery. The PMWNHF to nicotine ratio 
of Camel Lights was 9.7. 
EXAMPLE III 
A cut tobacco blend comprised 25% burley lamina, 40% flue cured lamina, 25% 
water treated stem and 10% sun cured oriental lamina. To this blend was 
added glycerol at a 10% loading level and magnesium chloride at a 1% 
loading level. The blend was thereafter subjected to a high level 
expansion process. The glycerol loading level on the expanded tobacco was 
8%. 
Using the thus obtained tobacco cigarettes were made which were to the same 
format as the cigarettes according to the invention of Example I. When 
smoked under standard machine smoking conditions, mainstream smoke 
component deliveries were found to be as follows: 
______________________________________ 
Component Delivery (mg) 
______________________________________ 
TPM 6.55 
Nicotine 0.54 
PMWNF 4.93 
Glycerol 1.63 
PMWNHF 3.30 
______________________________________ 
Thus the PMWNHF to nicotine ratio was 6.1 and the humectant represented 33% 
of the PMWNF.