Quality Aspects In Tobacco

• Quality in tobacco is currently an object of subjective evaluation and best defined as "that for which the buyer pays money".
• Thus quality determines the price of the tobacco leaves produced for marketing purposes.
• Sugars are considered to have a positive influence on quality while nitrogenous compounds a negative one.
• But it is necessary for a leaf to have too much sugar and some nitrogenous constituents because in absence of either of the two the smoke is insipid and lacks character.
• Thus the commercial value of a leaf is judged by its suitability for specific purposes of manufacture viz. tobacco used for smoking purpose must have a combustibility and fine aroma.
• In general the leaf characters, chemical composition of leaves, burning quality and aroma are the most important factors in determining the quality of a tobacco.

Leaf characters

• Leaf character is primarily hereditary in nature but it may slightly be modified with the growing season, nutrient conditions, planting density, topping and de-suckering etc.
• Size of leaves is a very important factor in cigar types than in most others because for cigar-wrappers normally the medium and shorter leaves are preferred.
• The prominence of leaf-veins is of a greater significance in cigar-wrapper types. Fine vein constitutes an essential characteristic of a high grade cigar wrapper.
• The angle formed by midribs and principle veins makes a better look of cigars and helps in fixing a higher price.
• Usually midribs and webs are waste products to the extent of 20-30 per cent in tobacco leaves and therefore, they affect the economy in usage of the products.
• Leaf thickness is next important factor for determining the value of the produce as the leaves of different thickness are used for different commercial purposes.
• Leaves used for pipe smoking mixtures and cigar wrappers are thinnest of all types, while good cigarette leaves and plug fillers usually are somewhat thicker. Leaf thickness is partly controlled by growing season, cultural- practices, etc.
• Crop grown under drought conditions produces small, thicker and heavier leaves, which are relatively less elastic in nature and can't be used as wrapper or filler.
• Apart from this the leaves produced under drought conditions have more sticky and gummy secretion which is composed of etheral oils and resins. Although they don't affect the quality and aroma but the look becomes deceptive.
• Leaf-colour, its depth and uniformity in shade over the leaf surface is equally important in selecting the grade of the leaf within the type.
• Leaves of light colour, being mild tobaccos, may present a high lustre while the dark coloured leaves, which are strongest ones, may have a dull and lifeless appearance.
• On individual plant the lower leaves are light coloured and top leaves are of darker shades.

Chemical composition of leaves

• Tobacco leaves contain a number of chemical compounds (alkaloids) which influence their quality. Of these polyphenols and carbonyls have an important bearing on flavour and aroma.
• Cellulose and minerals are deciding base materials for combustion. Glycosides cause bitterness in leaves.
• Soluble carbohydrates, especially sugars, are considered to have a positive influence on quality and nitrogenous compounds a negative one.
• Nicotine is the single compound which over rules all other chemicals in governing the quality.
• Nicotine is produced mainly in plant-roots and is carried through stem to the leaves where it is stored: Smoking enjoyment depends on a definite percentage of nicotine in manufactured products.

For Indian tobaccos the standard nicotine figures are

• 1-2% in cigarette
• 2-3% in cigar
• 6-8% in bidi,
• 3- 4% in cheroot (Lanka type produced in A.P.) leaves.
• The hookah types of tobacco contain 0.5-1.5% nicotine in Nicotiana tabacum and 2-3.5% in Nicotiana rustica varieties while snuff tobacco should have about 3.2-4.8% nicotine in their leaves.
• The nicotine content varies with different varieties, spacing, fertilisation, topping and de-suckering time, number of leaves on plant, other cultural practices and method of curing etc.
• Heavy soils, drought conditions and higher soil temperature produce leaves with higher nicotine and vice-versa.
• Nitrogen, being an integral constituent of nicotine, influences the content of nicotine in the leaves while all other nutrients have no effect.
• In recent years smoke tests are being made in relation to total partienlate matter (TPM) and nicotine content in smoke because of their suspected relationship with lung cancer and bronchitis.
• The tar content in the smoke has been found to be positively correlated with the resin content and nicotine content in the leaf.
• On an average the tar content (TPM) in cigarette tobacco is found to range between 30 to 38 mg/cigarette which smoke nicotine ranges between 1.92 to 3.02 mg/cigarette.

Burning quality

• The burning quality includes different elements of combustibility such as fire-holding capacity, the rate, evenness and completeness of the burn. The fire-holding capacity i. e. the property of continuing to glow without appearance of flame, depends upon the structure and composition of the leaf.
• A high grade smoking tobacco must have a good fire-holding capacity with relatively slow burn. Usually thin leaves burn quickly and because of that the cigar-wrapper often burns some what in advance of burning core (filler).
• In cigarette a free and more rapid combustion is favoured by smaller diameter of the filler.
• Formation of grains (pimple like projections) on the leaf surface, which are composed of Ca, Mg and potassium salts of citric and malic acids, which improve the fire holding capacity and finally the burning quality.
• Cellulose and related compounds, soluble carbohydrates and nitrates improve the combustion.
• Potassium, a major constituent of ash, results in a continued burning without flame. Mg and calcium have a controlling influence on the ashing process.
• The acidic compounds of ash, chlorine, phosphorus, silicon and sulphur, in general, tend to retard the combustion but chlorine, if present in sufficient quantities, is outstanding in its injurious effects.
• The concentration of these harmful and beneficial elements may be controlled to greater extent by a balanced fertilization of the crop.

Aroma

• The extent and type of aroma is greatly influenced by presence of polyphenols and carbonyls. Fermentation and aging of leaves are also found to affect the aroma.
• The quality of aroma apparently depends primarily on tobacco species and variety but soil and climatic factors are major factors in determining the strength of aroma.
• But the real factors responsible for nature and strength of aroma are yet not known.
• The upper leaves on the same plant are found to be more aromatic compared to the lower ones.

Cigar tobacco components	Texture	Qualities
Filler	Thick	Good burning taste and aroma
Binder	Medium to thin	Medium to thin
Wrapper	Very thin	With fine parallel veins and a pleasing lustre, finish

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Quality Characteristics of Flue-Cured Tobacco

Character	Traditional black soil	Northern light soil	Southern light soil	Karnataka light soil
Nicotine%	1.0 to 2.7	1.6 to 2.9	0.9 to 1.1	1.5 to 1.8
Total N%	1.5 to 2.5	1.8 to 2.7	2.3 to 2.6	1.9 to 2.7
Reducing sugars%	8.6 to 20.9	13.8 to 23.5	10.1 to 17.5	18.0 to 27.0
Chlorides %	0.5 to 2.0	0.7 to 1.5	0.5 to 0.9	0.1 to 0.2
Moisture equilibrium %	12.2 to 15.4	14.0 to 17.1	11.7 to 13.6	13.0 to 15.0
Pore valume (ml/g)	0.11 to 0.19	0.14 to 0.24	0.13 to 0.15	0.13 to 0.17
Filling value (cc/g)	2.6 to 2.8	2.2 to 2.8	2.6 to 3.5	2.9 to 3.3

Chemical Composition of Non-FCV Tobacco Types in India

Type	Total N%	Nicotine %	Reducing sugars %	Chlorides %	K %
Bidi (Anand)	3.15	9.71	2.28	1.80	1.90
HDBRG	2.59	3.89	1.09	0.40	2.02
Natu (Guntur)	2.97	2.79	2.36	0.42	2.29
Irrigated Natu (V.R. Gudem)	3.40	2.50	0.84	1.59	1.53
Burley (Chintapalli)	3.52	1.26	0.79	0.27	4.80
Chewing tobacco (Vedasandur)	3.22	2.93	-	5.08	3.20
Cigar tobacco (Vedasandur)	2.37	1.24	0.29	4.52	4.50
Cheroot tobacco (Vedasandur)	2.68	1.01	0.51	3.87	4.51
Chewing tobacco (Pusa)	3.11	3.70	1.98	1.28	3.25
Cigar filler (Dinhata)	3.51	2.05	1.37	0.38	4.62
Cigar wrapper (Dinhata)	3.45	1.44	1.11	0.46	5.11
Jati-Chama (Dinhata)	2.66	3.69	0.99	0.56	2.79
Jati-Podali (Dinhata)	3.05	4.02	0.82	< 0.44	1.89
Motihari-Hemti (Dinhata)	3.76	4.83	0.71	1.91	1.91
Motihari-Bitri (Dinhata)	4.12	6.64	0.82	0.42	1.66

Acceptable limits for important chemical constituents and quality indices in Flue-Cured Tobacco

Constituent/Quality Index	Acceptable limits
Total Nitrogen %	1.0-3.0
Protein Nitrogen %	0.4-1.3
Nicotine %	0.7-3.0
Total sugars %	10-26
% Total sugars / % Nicotine	8-14
% Total N / % Nicotine	< 1.0
% Nicotine / % Total alkaloids	> 0.95
Filling value at 60% R.H & 20° C	3.3-3.8 cc/g shreds
Equilibrium moisture content at 60 % R.H & 20° C	11-15%
Leaf burn	3-6 sec
Shatterability index	3

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Factors Affecting Tobacco Leaf Qualities

• The factors affecting tobacco leaf qualities can be divided into three main factors.

  (A) Genetical factors

  (B) Ecological factors

  (C) Cultural factors.

Genetical factors

• Curing behaviour, flavour, aroma, body, texture, colour retention, burning qualities etc. are expected to be genetically controlled to a greater or lesser extent, viz., sugar content is higher in flue-cured tobacco than in any other types.
• Similarly, carbohydrate content and nicotine content were found to be different in various types of tobacco.
• Position of leaves on stalk influences the leaf quality as the bottom leaves are relatively thin, light in weight and body, light in colour, mild and have good burning qualities.
• Passing up the stalk, the leaves become progressively thicker, heavier in weight and body rough, more gummy, stronger, darker in colour, more aromatic, but of poorer burning qualities.
• As regards the chemical composition, in general, passing from the lowest to the top most leaves of fully matured plant there is a progressive increase in content of total nitrogen, protein, nicotine and ammonia and a decrease in total ash, calcium, magnesium and pH value. While the content of soluble carbohydrates is lowest is the upper leaves and highest in the middle leaves of the plant. /li>
• Thus, it is observed from the same plant that on an average bottom 5- 6, middle 2-4 and top 1-2 leaves formed the three grades of qualities viz- superior, medium and inferior respectively which is roughly in the proportion of 6: 3 : 1.

Ecological factors

Soil

• Tobacco soil must be well drained, properly aerated with low inherent fertility. Soils with high sandy surface and friable sandy loam sub- soil surface, low content of organic matter, acidic reaction (desirable pH 5.0- .6.0) and good amount of potash, phosphoric acid and iron are preferred for quality leaf production.
• Heavy soils produce tobacco with higher nitrogen than the sandy loam or sandy soils. Tobacco grown on saline lands absorbs moisture quickly before and after drying, changes colour rapidly during storage and has poor burning qualities.
• These are mainly due to large quantities of Chlorine (more than 0.01 per cent in soil and more than 10 per cent in leaf) which plant takes up from the soil. Tobacco grown on paddy lands and tank beds becomes bleached.

Climate

• Temperature, humidity, the extent of rainfall and its distribution during the growing period of tobacco have considerable effect on the quality of leaf.
• High temperature and low relative humidity has harmful effects on leaf burn but the leaves are thick and aromatic.
• Lower temperature, due to slower rate of metabolic processes, the leaf does not ripen full and does not develop the desirable qualities.
• The desirable range of temperature for quality production of tobacco is 10-90°F.
• Rainfall desirably ranging from 50 to 125 cm during growing season of tobacco results in leaves with light weight, thin texture, light colour, less gummy, light body, reduced nicotine content and aroma but of better combustibility.
• Drought results in the production of leaves having all the reverse qualities.
• Effect of sunlight does not have much effect except that shade or prolonged cloudy weather reduces the thickness of the leaves, increases leaf area without any increase in total dry weight of leaves.
• Wind causes dryness of plants and may bring a temporary atmospheric and soil drought which may result in a poor quality leaves.

Cultural factors

Crop rotation

• The soils under continuous tobacco cultivation are depleted of humus because tobacco does not add much of organic matter to soil like most of the crops. Such soils produce poor quality tobacco leaves and have possibility of an increased disease and Orobanche (flowering parasite) infestation. Therefore, tobacco in rotation with legumes always gives higher and better quality leaves.

Planting material

• Hardened and healthy seedlings, obtained from pure seed of the suitable strain, should be planted for better quality tobacco production. The planting material should have the resistance to storm, diseases and rough handling while harvesting. It should have uniformity in ripening and stand with fewer smaller or no suckers.

Manuring

• Quality in tobacco, particularly in the smoking types, (which are the ones that have been mostly investigated) depends on the balance of the nutrients in the leaf.
• Nitrogen has the profound effects on larger leaf area, increased moisture content, increased organic acid, enzymatic activity and nicotine content but leaves have a poor carbohydrate content in them.
• Light green leaves of good quality are produced from plant partially starved of nitrogen.
• Phosphorus deficient plants produce narrower and smaller leaves of dark green colour, the rate of growth is slowed down and maturity is delayed, the leaves are dull and devoid of lustre on curing.
• Potash, in the smoking tobaccos, is responsible for improving burning qualities like completeness of combustion and fire holding capacity that is also influenced by amount of potash in leaf.
• The physical qualities of the leaf, e.g., elasticity, smoothness and low prominence of veins and the smoking qualities are attributed to the high potash in the leaf.
• Chlorine in excess amount injures the growth of the plant and reduces the quality (same as excess of Calcium) by producing thick and brittle leaves. It has an unfavourable effect upon the burning quality and stability of colour.

Time of planting

• Early planting of all the tobacco types other than hookah in late October to early November is better than late planting during late November and early December. While in case of hookkah tobacco the best planting time is 2nd fortnight of February than earlier or latter dates because the yield and quality both are found to be the best.

Plant Spacing

• Closer spacing gives higher yield of leaves but the closer spacing tends to reduce the size, body thickness and weight per unit area of leaves. While in case of slightly wider spacing the plants produce larger, thicker and heavier leaves, which are again not good for quality leaves. From yield and quality point of view a spacing of 90 cm x 50 cm or 120 cm x 60 cm is found to be optimum.

Irrigation

• Heavy irrigation spoils the quality of the leaf. While light irrigation at critical stages of the crop growth gives a sufficient boost without spoiling the quality of leaf. High moisture content of soil results in low content of nitrogen, nicotine, calcium and magnesium in tobacco leaf, although the yield is high. Such leaves are thin with poor burning quality.

Removal of sand leaves

• Bottom sand leaves are very trashy and are of inferior quality, thus it is uneconomical to use them. So two or three leaves from bottom must be removed once when plants are 30 cm tall and again when plants are 60 cm tall.

Topping and desuckering

• Topping results in bigger, thick leaves which are cured as heavy, dark in colour, oily, rough, leathery and stronger. But topping should never be carried out in fields of rank growth, in areas known to produce poor curing as this could further deteriorate production of top grade tobacco. Nicotine in the leaves consequent to topping depends on the height of topping being inversely related to the number of leaves left on the plants.

Height of topping

• Topping at 14 leaves would maximise the yield of hookah and chewing tobacco without impairing the quality. While in case of 'Motihari' tobacco, topping higher than 6 leaves tended to reduce and yield of first grade leaf.

Time of topping and desuckering

• The best quality leaves are found where the plants are topped at early flowering stage and the quality deteriorated as topping was delayed. This also decreases the sugar and nicotine content in cured leaves, Desuckering is usually done after 6- 7 days of topping, otherwise, topping will be useless for better quality leaf production.
• Generally 2-3 desuckerings are done. Apart from desuckering the topping is also followed by piercing of the main stem. It is done immediately after topping with 20-25 cm long needle. It increases cured leaf yield and of first grade leaf.

Harvesting method

• Correct harvesting helps in production of better quality leaves. Out of two methods of harvesting viz. priming and stalk cut method, in former method the leaves get sufficient time to attain optimum size till they mature and thus help in increasing more desirable grades of leaves.
• The sand leaves should be separated out from the harvest. Immature leaves are gummy and of poor combustibility, while over- matured leaves, on the other hand, become scrappy and lack elasticity. Thus the leaves lead to a high percentage of the low grade leaves.
• Bruised and wilted leaves produce unsatisfactory cures of poor quality. The green leaves should be handled carefully and these leaves should not be exposed to sun in the fields for long periods or allowed to wilt badly by exposure for longer periods in stringing sheds.

Time of harvesting

• Generally cigar and cheroot tobacco are ready for harvest 20 to 25 days after topping, as is indicated by yellowing of tip and margins, slight puckering and brittleness of the leaf which breaks on folding. The highest yield of excellent quality leaves are obtained from the crop harvested 3 weeks after topping than the crop harvested earlier or later.

Curing of leaves

• Temperature, relative humidity and air supply are the factors affecting curing process, which are responsible for fixation of colour, yellowing of leaves, and better quality of cured leaves. These factors vary from method to method of curing, thus selection of suitable curing method from the following must be done, with reference to quality of the finished products.

Name of the finished products	Method of curing
High quality cigarette	Flue curing
High quality cigarette	Rack curing
Inferior quality cigarette	Rack curing
Cigarcherootchewingsnuffand Bidi tobaccos	Ground or sun curing
Very low grade cigaretteBidi	Ground or sun curing
Chewinghookah and snuff tobaccos	Pit curing
Bidisnuffchewing and hookah tobaccos	Fire curing

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