Curing Burley Tobacco – Analyzing the Curing Environment · 2015-03-12 · Rel. Humidity: 80%, 90% Air Flow: 15 ft/min ... 2 week periods, C. Ky. Farm, 2005 118 119 91 92 115 171

1/14/06, 6/21/06 © BAE Dept., Coll. of Agric., U.Ky.G. A. Duncan, L .R. Walton

Curing Burley Tobacco Curing Burley Tobacco ––Analyzing the Curing Environment Analyzing the Curing Environment

A brief A brief review review

of of whatwhat’’s s good,good,

more on more on a way to a way to evaluate evaluate

the the environenviron--

mentment

ByByGeorge Duncan, Linus WaltonGeorge Duncan, Linus WaltonB.A.E. Dept ., Coll. Of Agric., U.Ky.B.A.E. Dept ., Coll. Of Agric., U.Ky.

presented atpresented at42nd Tobacco Workers Conference42nd Tobacco Workers Conference

Charleston, SC Jan. 2006Charleston, SC Jan. 2006with recent additionswith recent additions


Early studies by Jeffrey, 19401, 19462…

Best for burley:Temp. 60-90 ºF (daily mean) Relative Humidity 65-70% (daily mean)Air Flow 15 ft/min (minimum)

Note: Then 1288-2698 lbs/ac,thin, buff color leaf

and 15 ft/min ~ 1/6 mph

1References cited are listed at the end of this presentation.


O’Bannon, 19433…

Extensive study of wind effects on barn ventilation;vent doors open, closed;

graphics of temp., rel. hum. within barn:


Walton & Henson4, 1971…

Study of effects of exposure to periods of low relative humidity on quality…

Temperature: 50 º, 65 º, 80 º FRel. Humidity: 30%, 45%, 60% Air Flow: 15 ft/minTimes of Exposure: 0, 12, 24, 48, 72, 96 hrsStages of cure: Initial (green), Yellow

Bur. 21, cured at 70 F and 70% R.H. except for exposure times



Results: Minimum periods of exposure required for 6 ¢/lb to 10 ¢/lb decline in support price…

Rel. Humidity . 30% 45% 60%

Temperature Exposure time in hours

50ºF 12 48 7265ºF 72 96 *80ºF ** * **

* 5 ¢/lb decline after 96 hrs** No damage for exposure up to 96 hrs

(additional comments made in paper)



Study of effects of exposure to periods of high relative humidity on quality…

Temperature: 50º, 65º, 80º FRel. Humidity: 80%, 90% Air Flow: 15 ft/minTimes of Exposure: 0, 48, 96, 144, 192, 240 hrsStages of cure: Initial (green), Yellow

Bur. 21, cured at 70 F and 70% R.H. except for exposure times



Results: Decline in support price after 240 hrsexposure by prediction equation…

Initial Stage Yellow Stage

Temperature 80% 90% 80% 90%50ºF 0 9¢ 1¢ 1¢65ºF 0 3¢ 1¢ 8¢80ºF 2¢ 1¢ 4¢ 4¢

(additional comments made in paper)


Many other burley studies since the 1970’s ..

J. Bunn, W. Henson, L. Walton, L. Bush, H. Burton, L. Davis, G. Duncan, others...

onbulked stalkshand, machine primed leaves,

heated air & natural air w/fanleaves cured on & off the stalkconcurrently field cured on frames, in ‘structures’,

plastic covered, and in barns…


Early to mid 1980’s and continuing,a major cured burley concern…

N i t r o s a m i n e s !!!!

Affected by- -Genetics,Cultural practices,Curing,Storage & Handling

A Finding: TSNAs develop from browning phase on throughout curing with ‘high’ moisture…


Now, continue with curing emphasis & means of evaluating ‘good’ curing…


Outside Ambient Temperature & Relative Humidity, C. Ky. Barn, 2005

20.025.030.035.040.045.050.055.060.065.070.075.080.085.090.095.0

100.0

08/2

7/05

08/2

9/05

08/3

1/05

09/0

2/05

09/0

4/05

09/0

6/05

09/0

8/05

09/1

0/05

09/1

2/05

09/1

4/05

09/1

6/05

09/1

8/05

09/2

0/05

09/2

2/05

09/2

4/05

09/2

6/05

09/2

8/05

09/3

0/05

10/0

2/05

10/0

4/05

10/0

6/05

10/0

8/05

10/1

0/05

10/1

2/05

10/1

4/05

10/1

6/05

10/1

8/05

10/2

0/05

10/2

2/05

10/2

4/05

10/2

6/05

10/2

8/05

10/3

0/05

11/0

1/05

11/0

3/05

11/0

5/05

11/0

7/05

11/0

9/05

11/1

1/05

11/1

3/05

11/1

5/05

11/1

7/05

Date

Tem

p., R

H

RH Temp

Method to evaluate environment,e.g. How to ‘visualize’ good curing…

A lot of ‘overlapping’ lines here!! Let’s improve the analysis > >

4 day high

Humidity 6 day h.h.5 day h.h.


Recent chamber studies6, 7 indicate 75% ‘average’ R.H. is best for current burley. Then consider 10% above & below as ‘good’ range…

75%

85%

65%

A Concept… consider daily cycle of RH…


Now, let’s analyze hourly RH data per the following sample data in a spreadsheet…

192

155

164

343Sum

173

186

177

160

30.0%40.0%30.0%%

189

182

169

>85%65%-85%<65%RH

Use logic to put a ‘1’ in one of 3 columns according to RH values, then sum the ‘1’s & calc. %:


which represents the cumulative ‘Low Humidity’, ‘Good Humidity’ & ‘High Humidity’ hours:

30.0%

40.0%

30.0%

00.5

11.5

22.5

33.5

4C

umul

ativ

e H

ours

<65% 65%-85%

>85%

Relative Humidity

And plot the sums as a bar graph,


Now consider data from a Central Ky. Burley Barn8 in 2005..


Hours x Outside Relative Humidity, 2 week periods, C. Ky. Farm, 2005

118 119

91 92

115

171

77

91

112102 100

111

142

127133

142

121

55

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/19/2005

Date (ending of 2 week period)

Cum

ulat

ive

Hou

rs

<65% 65%-85% >85%

Ambient RH Outside the barn

Data is grouped in two week periods, representing typical ‘yellowing’, ‘browning’ and ‘leaf drying’ & ‘midrib drying’ stages:

Note rather good ‘balance’ of low & high RH around the daily average except for more ‘humid’ Aug., Oct. & ‘dry’ Nov. periods.


p y, y ,

20.025.030.035.040.045.050.055.060.065.070.075.080.085.090.095.0

100.0

5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5

Tem

p., R

H

RH Temp


0102030405060708090

100110120130140150160170

9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/19/2005Date (ending of 2 week period)

Cum

ulat

ive

Hou

rs

<65% 65%-85% >85%

Now compare ‘overlapping’ lines of RH plot with bar graph, note ‘humid’ period in Aug. & Oct..(RH>85-95%), ‘dry’ period in Nov.(mostly 25-80%)

35%118

23%77

42%142

35%119

27%91

38%127

27%91

33%112

40%132

27%92

30%102

42%142

34%115 30%

100

36%121

51%171

33%111

16%55


Hours x Inside Relative Humidity, 2 week periods, C. Ky. Barn, 2005

0102030405060708090

100110120130140150160170180190200210220230

9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/13/2005


Cum

ulat

ive

Hou

rs

<65% 65%-85% >85%

RH Inside the barn, middle of 5 tiers.

Now look at data inside same barn (middle of 5 tiers), with vents managed for ‘good’ curing…Aug. & Oct. periods of high outside RH had similar ‘higher humidity’ in the barn,

(vents could have been opened more), however prevailing levels of good 65%-85% RH occurred during Oct. yellowing to browning and Nov. drying!

Note: Only 8 days of datafor 11/13/05

41%138

2%7

57%191

11%37

50%168

39%131

14%47

61%205

25%85 22%

72

34%113

45%151

29%97

50%167

22%73

57%109

38%74

5%10



0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/19/2005


Cum

ulat

ive Hou

rs

<65% 65%-85% >85%

Hours x Inside Relative Humidity, 2 week periods, C. Ky. Barn, 2005

0102030405060708090

100110120130140150160170180190200210220230

9/10/2005 9/24/2005 10/8/2005 10/22/2005 11/5/2005 11/13/2005


Cum

ulative Hou

rs

<65% 65%-85% >85%

Comparison of ‘Outside’ & ‘Inside’ RH graphs for C. Ky. Barn, note dominance of ‘good’ curing conditions inside barn.

RH Inside the barn

RH Outside the barn35%118

23%77

42%142

35%119

27%91

38%127

27%91

33%112

40%132

27%92

30%102

42%142

34%115 30%

100

36%121

51%171

33%111

16%55

41%138

2%7

57%191

11%37

50%168 39%

131

14%47

61%205

25%85 22%

72

34%113

45%151

29%97

50%167

22%73

57%109 38%

74

5%10


TSNA data9 for five locations in the C. Ky. Barn:(Variety: TN90)

Samples from C. Ky. Barn, 2005

Location NNN NAT NAB NNK TSNAug g-1 ug g-1 ug g-1 ug g-1 ug g-1

BC01 0.73 0.85 ND 0.14 1.72BC03 0.83 1.44 ND 0.16 2.43BC04 0.93 1.74 ND 0.19 2.86BC05 0.89 1.44 ND 0.17 2.50BC06 1.06 1.39 ND 0.19 2.65

AVG: 2.43


RH Lexington Airport

Now go to another location: RH at Lexington Airport10 showing rather ‘dry’ curing weather for 2005


RH inside UK Spindletop Farm 10 miles away from Airport for a selected curing period,generally ‘good’ curing except for a two week Oct. ‘humid’ period.


Samples from U. Ky. Barn & Lab Chamber Curing, 2005

Location NNN NAT NAB NNK TSNAug g-1 ug g-1 ug g-1 ug g-1 ug g-1

UK Barn 1.36 1.63 0.055 0.15 3.20BAE Lab #1 0.78 1.30 ND 0.18 2.26BAE Lab #2 1.12 1.70 ND 0.23 3.05Note: BAE Lab #1 cured at constant 70 F, 75% BAE Lab #2 cured at daily cycle of 60-80 F, 50%-90%

TSNA data9 for U.Ky. Barn and Chamber Curing, 2005:(Variety: KT204) 11


RH at Lexington Airport10 for 2004 showing more ‘humid’ periods.


RH at Lex. Airport10 for 2003 showing generally good curing with 3 ‘humid’ periods.


RH at Lexington Airport10 for 2002 showing generally 2 ‘dry’ periods, 1 ‘humid’ period, otherwise good curing periods.


RH at Lexington Airport10 for 2001 showing generally good early curing with 3 ‘dry’ periods in latter part of season.


Summary of RH at Lexington Airport10 for 5 curing seasons.Note 2004 9% hours more ‘humid’, 2005 11% hours more ‘dry’.


11 days

14days

Missing

14days

Now analyze RH at Raleigh-Durham Airport12 for 2005, showing early ‘humid’ period, later ‘dry’ period, otherwise rather ‘good’ curing conditions.

Weather data missing in several periods


RH at Raleigh-Durham Airport12 for 2004, showing predominant ‘humid’ periods!

Hours x Relative Humidity, 2 week periods, Raleigh-Durham , 2004

8090

62

73 70

54

90

10698 99

8085 85

96 98108

158

147

194

178 181186

148

122

0102030405060708090

100110120130140150160170180190200

8/14/2004 8/29/2004 9/12/2004 9/27/2004 10/11/2004 10/25/2004 11/8/2004 11/22/2004

Dates (ending of 2 week period)

Cum

ulat

ive

Hou

rs

<65% 65%-85% >85%


RH at Raleigh-Durham Airport12 for 2003, showing predominant ‘humid’ periods except for mid Nov.


RH at Raleigh-Durham Airport12 for 2002, showing mostly ‘humid’ periods except for early ‘dry’ period & mid ‘good’ period!

Hours x Relative Humidity, 2 week periods, Raleigh-Durham, 2002

196

86 86

69 71

35

50

71

89 91 91

138

113

7065

72

51

159 159

129

152

231221

193

0102030405060708090

100110120130140150160170180190200210220230

8/14/2002 8/28/2002 9/11/2002 9/25/2002 10/9/2002 10/23/2002 11/6/2002 11/20/2002


Cum

ulat

ive

Hou

rs

<65% 65%-85% >85%


RH at Raleigh-Durham Airport12 for 2001, showing mixture of ‘humid,’ ‘good’ & ‘dry’ periods!


Summary of RH at Raleigh-Durham Airport12 for 5 curing seasons.Note 2005 rather ‘good’ curing season, 2001 ‘maybe’, other 3 very ‘humid!’

RH x Percentages of Hours by Year, Raleigh-Durham, 2001-2005

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

2001 2002 2003 2004 2005

Year

Perc

enta

ge o

f Hou

rs

<65% 65%-85% >85%

35%

40%

25% 25%27%

48%

23%

28%

49%

23%

28%

49%

37%

33%31%


Comparison of Lexington & Raleigh-Durham for 2001-2005 curing seasonsLex. shows mostly ‘good’ curing seasons with one having 9% ‘humid’ & one 12% ‘dry’ hours.

Raleigh-Durham shows one ‘good’ curing season, one ‘maybe’, three with 21% more ‘humid’ hours.

Hours x RH Percentages by Year, Lexington, 2001-2005

40%

30%

24%25%

45%

37%36%

38%

33% 34%

23%

34%

39%42%

21%

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

2001 2002 2003 2004 2005Year

Percen

tage

of H

ours

<65% 65%-85% >85%


1. Principles and brief studies of air curing conditions for burleytobacco have been reviewed.

2. A method for analyzing relative humidity data to graphically andvisually portray ‘dry’, ‘good’ and ‘humid’ conditions has been presented.

3. An analysis of Central Kentucky, Lexington, KY, and Raleigh-Durham, NC, weather data shows the prevalence of ‘dry’, ‘good’& ‘humid’ curing seasons in traditional and non-traditional burley curing regions.

4. For the past 5 years, Lex. shows mostly ‘good’ curing seasons with one having 9% ‘humid’ & one 12% ‘dry’ cumulative hours.

5. For the past 5 years, Raleigh-Durham shows one ‘good’ curing season, one ‘maybe’, three with 21% more ‘humid’ cumulative hours.

6. Additional years of data & locations should be studied for more longer-term analyses of burley curing conditions.

Summary:


1 Jeffrey, R. N. The Effects of Temperature and Relative Humidity During and After Curing upon the Quality of White Burley Tobacco. Bull. No. 407, Ky. Agr. Exp. Sta., Univ. of Ky., Lexington, July, 1940

2 Jeffrey, R. N., The Relation of Curing Conditions to Quality in Burley Tobacco. Bull. No. 496, Ky. Agric. Exp. Sta., Univ. of Ky., Lexington, Dec., 1946

3 O’Bannon, Lester S., Distribution of Temperature and Relative Humidity Within a Burley Tobacco Barn. Bull. No. 444, Ky. Agric. Exp. Sta., Univ. of Ky., Lexington, May, 1943

4 Walton, L. R., and W. H. Henson, Jr. Effect of Environment During Curing on the Quality of Burley Tobacco: I. Effect of Low Humidity Curing on Support price. Tob. Sci. 15:54-57. May 14, 1971

5 Walton, L. R., and W. H. Henson, Jr. Effect of Environment During Curing on the Quality of Burley Tobacco: II. Effect of High Humidity Curing on Support price. Tob. Sci. 17:25-27. 1973

6 Duncan, G. A., M. Montross, J. Calvert, D. Smith, D. Mereand. Ongoing Studies of Barn, Field and Chamber Curing Environments on TSNA Formation in Burley Tobacco. Presented at the 2002 CORESTA Congress, New Orleans, LA, Sept. 22-27, 2002, Abstract in Proceedings.

References Cited:


7 Duncan, G. A., J. Calvert, D. T. Smith and D. C. Middleton. Further Studies of Fertility levels and Barn and Chamber Curing Environments on TSNA Formation in Burley Tobacco. Presented at the 2004 CORESTA Congress, Kyoto, Japan, 3-7 Oct., 2004, Abstract in Proceedings.

8 Thanks to Mr. Ben Crain and Family, Liberty Hall Farm, Woodford Co., and to Mr. David Talley, Grower, for cooperation, support and assistance with the 2005 curing study.

9 Thanks to Dr. Lowell Bush & Lab Technicians, Dept. of Plant and Soil Science, U. Ky., Coll. of Agr., for the TSNA analyses.

10 Data downloaded from archives of Ag. Weather Center, U. Ky., Coll. Of Agric., Mr. Tom Priddy, Dir., http://wwwagwx.ca.uky.edu/

11 Thanks to Dr. Bob Pearce and Mr. Jack Zeleznik, Dept. of Plant and Soil Science, U. Ky., Coll. of Agr., for the mature tobacco plants.

12 Thanks to Mr. Tom Priddy, Dir., Ag. Weather Center, Col. Of Agric. For obtaining the NOAA weather records for the Raleigh-Durham Airport location for Aug.-Nov., 2001-2005.

*** End ***

References Cited (Cont’d):

Documents

Curing Burley Tobacco – Analyzing the Curing Environment · 2015-03-12 · Rel. Humidity: 80%, 90% Air Flow: 15 ft/min ... 2 week periods, C. Ky. Farm, 2005 118 119 91 92 115 171