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Harvesting, Processing, and Quality Assessment of Cinnamon Products 131
Extraction and processing of the bark
The process of bark extraction involves scraping the bark with a steel scrapper, peeling, filling up and drying. The outer cork from the bark is scraped prior to peeling. Then the bark is thoroughly rubbed with a wooden or brass rod to loosen it from the woody
Chemical Synthesis Chemical Synthesis
Peeling Cutting
HARVESTED
CINNAMON STEMS PEELEDBARK STICKS FIRE WOODSOLD AS
LEAF KATTA QUILLS
Steam Distillation Steam Distillation Steam Distillation
LEAF OIL KATTA OIL ROUGH
QUILLS Exported on
Request QUILLSFINE
EXPORTED TO MARKETS EUROPEAN QUILLINGS CHIPS FEATHERINGS KOH
EUGENOL LEAF TERPENES (CinnamicaldehydeBARK OIL 30–75%)
CINNAMAL
DEHYDE EXPORTED TOS.America, USA
EUGENYL
ESTERS ISO EUGENOL& ESTERS VANILLIN
CINNAMYL ESTERS
Figure 5.1 Flow diagram of cinnamon processing.
132 K.R. Dayananda, U.M. Senanayake and R.O.B. Wijesekera
stem. A longitudinal line is then drawn on the bark from end to end with a sharp pointed knife. A similar line is drawn on the opposite side of the bark. By skillfully maneuvering the knife, two equal halves of long bark are peeled off from either side of the stick (Fig. 5.3a).
The bark halves are packed one inside the other until cigar like quills are obtained. The worker sits with a board and a measuring stick 107 cm long, to which is attached a wooden lifter (known in the local language as ‘Pethi Kotuwa’). The compound quill is assembled on the board (Fig. 5.3b). When it has reached the required length the end is trimmed with scissors and it is gently lifted and kept on the mat for drying. The hollow inside of the quill is then packed with pieces of thin bark, which are unsuitable for forming a single quill. The prepared quills are arranged in rows suspended by ropes and dried in the shade for a few days. They are never dried in direct sunlight. The dried bark turns a pale yellow colour. Sometimes the bark is fumigated with sulphur dioxide to obtain a uniform yellow colour and to kill any insects and microorganisms in the quills. The dried bark is quite hard and can be handled without much breakage. The moisture content at this stage will be about 10%. They are then packed in polythene lined jute bags.
Cinnamon quills prepared by experienced peelers are of uniform thickness from end to end. They have a characteristicly smooth skin and uniform yellow colour. The dried quills are tightened into small bundles, each bundle containing about 30–40 quills. The edges are then trimmed, making them ready for marketing (Fig. 5.4).
Cinnamon quills produced in Sri Lanka are specially designated as Ceylon Cinnamon, as there are differences in the flavour quality of the product. Products produced in Seychelles and Madagascar are also found in the market and are named accordingly. Dark brown patches found on the surface of quills are called foxing. Depending on the amount of foxings, size and colour they are graded. Quills free from foxing are con- sidered to be the best.
After systematic grading the cinnamon quills are exported. The characteristics considered for the grading of Sri Lankan cinnamon quills are given in Annex 5.1. It is significant that grading is carried out by the exporter and not by the producers. The finest and smoothest quality quills are graded as (00000) five zeros and the coarsest as zero (0). Over-matured barks are generally coarser and producers obtain an advantage in terms of weight. However, since high quality five zero quills fetch the highest price, producers should be induced to supply the better quality quills without consideration of weight. Another grade called Alba, fine thin bark rolled in to pencil like quills, are also produced for special export orders.
Cinnamon Products
As discussed earlier, cinnamon quills represent the most valuable product originating from the cinnamon bush. However, there are several other by-products generated during the processing of quills (Fig. 5.5). They are classified into three major commer- cial groups.
Quillings
Quillings are made from broken pieces and splits of all grades of cinnamon quills. The main characteristics of quillings are their shapes and sizes. The aroma and taste of
(a)
(b)
Figure 5.3 (a) Cinnamon peelers at work (tools used to peel the bark are in the foreground and harvested
134 K.R. Dayananda, U.M. Senanayake and R.O.B. Wijesekera
quillings are the same as the quills, even though they are marketed as medium quality cinnamon. They contain featherings and chips but their quantities should not exceed 3% by mass. If proper precautions are not taken during the processing, extraneous matter including pieces of wood, stems or twigs may get mixed with the quillings. Quillings are separated from the quills in the preparation of quills and they are sep- arately dried in shade followed by sun drying.
Featherings
Featherings are feather-like pieces of inner bark consisting of shavings and small pieces of bark left over from the process of making quills. Scrapings from the bark or small twigs and stalks of cinnamon shoots, including a minimum quantity of chips, are also considered as featherings. The product is marketed as medium quality cinnamon.
Harvesting, Processing, and Quality Assessment of Cinnamon Products 135
Chips
Chips are not peeled out from the stem. Instead they are scraped off from the greenish brown, mature, thick pieces of bark, which are inferior quality cinnamon. The outer bark, which has been obtained by beating or scraping the shoots is also considered to be chips.
Chips are graded into two categories,
Grade 1 – Those containing small featherings obtained by scraping very small twigs. They contain a small amount of other bark material.
Grade 2 – Those containing inner and outer bark and pieces of wood.
Depending on the extent to which chips are free from extraneous matter such as refuse and dust, the chips are cleaned by washing or bleaching and are further divided into four types (type 1, 3, 0 and 00).
The cleanliness and levels of dust, mould and other pathogenic organisms are important aspects of the production of cinnamon quills, quillings, featherings and chips. Consumers directly use them in most of the food formulations. It has been reported that compounds such as cinnamic aldehyde and eugenol found in them inhibit the growth of micro- organisms (Bullernan et al., 1977). The general requirements for cinnamon bark are given in Table 5.1.
Products Based on Cinnamon Bark and Leaf
Cinnamon quills and remnants of bark are prepared into various other forms, such as small pieces of quills 7–15 cm long or as a powder. For most baked products, cinnamon is used in powdered form. Finely ground cinnamon quills are the best, however, flavour and odour characteristics become less than those of quills. The essential oil content of the powder is less compared to the bark due to losses during the process of grinding. Adulteration of cinnamon powder with lower grade bark is commonly practiced (Llewellyn et al., 1981).
Airtight containers made of glass or wooden boxes with an outer wrapping of polythene are generally acceptable as packaging for cinnamon products. However, a shelf-life of over two years is generally not recommended for cinnamon bark or their products since flavour and odour characteristics tend to change with time.
Cinnamon oils
In the world trade, the oils from the cinnamon species are classified as cinnamon oil, cas- sia oil and camphora oil, according to the place of origin. The true cinnamon oils come from Sri Lanka and they are accordingly classified as “Cinnamon Leaf Oil” (ISO 3524). Cassia oils come from China, Taiwan and Burma and are called Chinese, Taiwanese or Burmese cassia oils, respectively. Unlike the Sri Lankan cinnamon oils where a category for both bark and leaf oil exists, only one category exists in cassia oils. This is because during distillation cassia bark, leaves and twigs are distilled together to obtain one category of oil. Camphor oil, although chemically different from either cinnamon or
136 K.R. Dayananda, U.M. Senanayake and R.O.B. Wijesekera
Table 5.1 Chemical requirements for cinnamon bark Requirement
Sri Lanka Seychelles type and Reference to ISO Madagascar type Recommendations cinnamon
Moisture % w/w 12.0 12.0 ISO – R 939
Total ash % w/w on 5.0 7.0 ISO – R 928
dry basis max.
Acid insoluble 1.0 2.0 ISO – R 930
ash % (w/w) on dry basis max.
Volatile oil ml/100 g Whole 1.0 0.4
on dry basis min. ground 0.7 0.3
cassia oils, is obtained from distilling the bark and wood of the Cinnamomum camphora tree. China and Japan are the main producers of this oil.
Cinnamon bark oil
Cinnamon bark oil is one of the expensive essential oils in the world market. The price or value of bark oils, largely depend on the material used to distill the oil. Even though quills are the best to obtain quality bark oil, quills are not always used for the distillation. The quillings when fresh provide oil of equal quality and are usually employed in distillation as the preferred raw material on grounds of economy as well as quality.
Like most of the other essential oils, cinnamon oils are also produced by hydro- distillation (Wijesekera, 1989). Hydro-distillation implies water-cum-steam distilla- tion. In Sri Lanka traditional distillation units are built on the hydro distillation principle (Fig. 5.6). To obtain commercial cinnamon bark oil, broken pieces of quills, quillings, pieces of inner bark from twigs and twisted shoots are distilled. Harvesting, Processing, and Quality Assessment of Cinnamon Products 137
Hydro-distillation units are heated by direct firing. Bark or other parts of the inner bark are placed in the still and direct fire is introduced. The distillate produced from the still body is first passed through a pre-cooler and then through a large static water condenser. In Sri Lanka a large number of existing cinnamon oil distillation units are still of traditional design. Although present day distillers introduced several modifications to modernise the design (Fig. 5.7), they have not made any significant differences to the system. These old stills are still adequate to distill the oil from the bark. They are made out of copper or tin lined copper or steel and hold around 50 kg of bark. The still body is built over a brick or mortar hearth and direct fire is introduced from the bottom. Cinnamon bark is placed in the still, which is partly filled with water. The condenser is a static copper tubing immersed in a large water tank. Recently a precooler has been introduced in between the still body and static condenser. The precooler cools the distillate to about 70 °C when it is sent into the main condenser. All the time the precooler is kept cold by cold water. Certain distillers have a battery of still bodies with a common static water condenser. Five to six copper, aluminium or stainless steel Florentine vessels in a cascade arrange- ment are placed to collect the distillate. As cinnamon oils are heavier than water, condensed oils collect at the bottom of vessels. Loading and unloading of the bark is done manually. The time taken to distill a batch of 40–50 kg of bark is around four to five hours and a yield of 0.5–0.7% of oil on dry weight basis is obtained (Anon, 1993).
Cinnamon bark oil is graded according to its cinnamic aldehyde content (CS 185, 1972).
138 K.R. Dayananda, U.M. Senanayake and R.O.B. Wijesekera
Harvesting, Processing, and Quality Assessment of Cinnamon Products 139
Figure 5.8 Diagram of a traditional cinnamon leaf oil distillation unit.
KETTLE
FURNACE
STILL PRE COOLER
STATIC CONDENSER
Cinnamon leaf oil
Leaf oil distillations are normally carried out in large distillation vessels (200–500 kg) (Fig. 5.8). Cinnamon leaves are obtained as a by-product of the cinnamon industry. When the shoots are harvested for bark, the leaves and twigs are trimmed in the field. Before distilling the leaf oil, the trimmed leaves are allowed to remain in the field for three to four days. Traditional leaf oil distillation units consist of a wooden still body with a copper goose neck lid. The condensing system is similar to the bark oil-distilling unit. The steam is generated in a separate kettle like external boiler. The condensed distillate is collected in a series of Florentine vessels (Fig. 5.8). Due to the low solubility of leaf oil in water it turns milky white in colour. Oil separated water is kept stored for days before complete separation of oil from the water. Since leaf oil is heavier than water, oil collects at the bottom of the Florentine vessel. Due to oxidation and to reac- tions with copper or steel vessels, the oil turns usually dark brown in colour. It takes about six to seven hrs to distill one batch of leaf, normally a yield of 1.0% oil on dry weight basis is obtained. After months of operation, a dark resinous material is found in condenser tubes. This is removed by burning condenser tubes in open fire.
Cinnamon leaf oil is graded according to the eugenol content (CS 184, 1972).
Supercritical fluid extraction (SCFE) of cinnamon
SCFE is a versatile tool for addressing the disadvantages of the conventional extraction technologies of essential oils and oleoresins. In this process the ground spice is brought into contact with a supercritical solvent at a relatively high pressure ranging from 60–300 bar at a temperature 35–70 °C. The supercritical solvent, after getting enriched with the solute, is passed through a micrometer valve or pressure reducing valve, where the pressure on the separator side is much less and the temperature much lower due to the adiabatic expansion of the supercritical solvent. This results in lower solubility of the solute leading to the separation of the solute from the solvent. Once the material is separated the gas is compressed back to extract the material
(Tiwari, 1989). CO2is the most commonly employed SCF. CO2is available freely, it
is cheap, non-flammable, non-toxic and non-corrosive. It behaves either as a polar or non-polar solvent depending on pressure and temperature employed. CO2 is liquid
below its critical point (31.2 °C, 7.38 milli pascal pressure) and above that it exists as a super critical fluid. The technical advantages of using SCFE for spices were studied by Udayasankar (1989).
Coarsely ground cinnamon bark is extracted with supercritical CO2using pressures
of 300, 400, 500 and 600 bar. The yield is around 1.4% as compared to steam distilled (0.5–0.8%). No significant differences were reported sensorily between the SCF extract and steam distilled oil and extracts (Pruthi, 2001). L CO2extract of powdered bark is
a mobile oil without the dark coloured waxes and resins normally encountered with the bark oleoresin prepared with chemical organic solvent. The CO2selective extract is
more soluble in foods, while the resinous compounds have a slight fixing effect on the flavour components of cinnamon and cassia bark extracts. However, the SCFE process is not practiced for commercial cinnamon or cassia oleoresin production because the process is very costly and the product does not differ much in quality from the solvent extracted product.
Cinnamon oleoresin
Oleoresins are solvent extracts of spices that contain the volatile oil, non-volatile resinous material and the active ingredient that characterises the spice as hot or pungent when such an ingredient is present. The solvents commonly used for the preparation of the oleoresins are acetone, ether, ethanol, propanol or methylene chloride. Ethanol was at one time the preferred solvent but is no longer used due to its high cost. Acetone is now the most commonly used solvent for oleoresin production. In solvent extraction the selected solvent is allowed to percolate down through coarsely ground spice which is loaded in a percolator. The bottom drain of the percolator is kept open for the escape of air. When all the material is soaked the bottom drain is closed and sufficient contact time is given to reach the solutes into the solvent. After the contact time, the extract, called “micella”, is drained and collected.
For oleoresin production either the Soxhlet extraction method or the batch counter current extraction method (CCE) is industrially practiced. In the Soxhlet method the solvent is allowed to percolate through the bed of material several times, which involves continuous heating of the extract. In the CCE method, which is very widely used, the powdered spice is packed in to a series of extractors and extracted with a suitable selected solvent. The solvent moves from extractor to extractor and the dilute extract is allowed to percolate through the spice. The concentrated extract obtained first from each extractor is withdrawn for solvent removal in the production of oleoresin.
The micelle obtained from the extractor is distilled to get the finished product. Most of the solvent (90–95%) present in the micella is recovered by normal atmospheric pressure distillation, while the remaining solvent is taken off by distillation under reduced pressure. The trace amounts of solvent are finally removed by either the azeotropic or extractive distillation method using an innocuous solvent like ethyl alcohol. Alternatively, bubbling nitrogen into the thick viscous material is carried out to drive away the residual solvent. The maximum permitted residual limits for some of the solvents are 30 ppm for acetone and chlorinated solvents, 50 ppm for methyl alcohol and isopropyl alcohol and 25 ppm for hexane (CFR, 1995). After distillation
the oleoresin is stored in suitable containers such as S.S. (stainless steel) drums or epoxy coated HDPE (high density polyethylene) containers.
Pharmaceutical preparations
The following preparations utilising cinnamon are listed in pharmacopoeias such as the British Pharmacopoeia (BPC) the Indian Pharmacopoeia (IPC) and the Argentinean Pharmacopoeia (AP).
Compound cinnamon powder (BPC) Distilled cinnamon powder (BPC) Concentrated cinnamon water (BPC) Tincture of cinnamon (BPC)
Compound tincture of cinnamon (TPC) Aromatic chalk mixture (IPC)
Ammoniated quinine and cinnamon elixir (BPC) Cinnamon spirit (BPC)
Cinnamon syrup (AP)
Cinnamon Standards and Specifications
Details of Indian and international standards laid down for Sri Lankan cinnamon products are given in Annex 5.1. The Indian standards cover cinnamon (whole) and the ISO specifications cover cinnamon whole and cinnamon powder (Sri Lankan cinnamon, Seychelles cinnamon), in addition to their storage, sampling and testing. Annex 5.2 gives the safety regulations for cassia leaf oil and cinnamon bark oil. Annex 5.3, pro- vides the cleanliness specifications prescribed by ASTA, ESA and the honest trading practices of Germany.
References
Anonymous (1977) Sri Lanka Standards, SLS 81 Part 1 and Part 2. Specification for Cinnamon. Sri Lanka standards-Specifications for cinnamon oil:
• CS 184 – Specification for cinnamon leaf oil
• CS 185 – Specification for cinnamon bark oil
Anonymous (1993) Proceedings of a Workshop on the Technological Aspects of the Production and Processing of Essential Oils in Sri Lanka, Institute of Chemistry, Ceylon.
Bullernan, L.B., Lieu, F.Y. and Seier, S.A. (1977) Inhibition of growth and aflatoxin production by cinnamon and clove oils, cinnamic aldehyde and eugenol. J. Food Sci., 42, 1107–1108. CFR (1995) Code of Federal Regulations, 21, CFR 173.2, Washington, USA.
International Standard Organization Standards (ISO):
ISO 3524 – Cinnamon Leaf oil ISO 6538 – Cassia Leaf Oil ISO 6539 – Cinnamon specification
ISO/R 928 – Spices determination of water insoluble ash