EFFECTS OF CHEMICAL PRETREATMENT AND DRYING TEMPERATURES ON THE COMMERCIAL QUALITY OF CARDAMOM...

EFFECTS OF CHEMICAL PRETREATMENT AND DRYING TEMPERATURES ON THE COMMERCIAL QUALITY OF

CARDAMOM (Elettaria cardamomum)

SARATH G. ILANGANTILEKE'.', CHINTHAKA KARUNARATNE' and MALINIE SENANAYAKE3

'Division of Agricultural and Food Engineering Asian Institute of Technology

Bangkok, Thailand 'Department of Civil and Environmental Engineering

University of Melbourne Victoria, Australia

'Department of Export Agriculture Ministry of Export Agriculture

Sri Lanka

Accepted for Publication July 15, 1993

ABSTRACT

R e effects of processing conditions on quality of cardamom (Elettaria cardamomum), were tested using a predrying treatment of 2 % sodium carbonate and drying temperatures of 35C, 45C and SSC, when drying was done continuously or in stages. Percent chlorophyll removal, total oil and essential oil content, % splits and % out-turn were determined in Chemically pre-treated and non-treated cardamom. The chlorophyll content was best retained in the chemically treated cardamom at 45C drying temperature. m e loss in totai oil content was minimum for the chemically pre-treated cardamom at a drying temperature of 45C, while maximum terpenoids were retained at 45C in the untreated cardamom. The % splits was lowest for the untreated product continuously dried at 45C and the % out-turn was highest for the chemically treated cardamom at 45C drying temperature. The recommended treatment conditions to meet trade quality standards were found to be a 45C drying temperature and chemically pretreated, continuously dried cardamom.

INTRODUCTION

The cultivation of cardamom (Elettaria cardamomum), is confined to India, Sri Lanka, Guatemala, Costa Rica, Salvador and parts of Southeast Asia. The

4To whom correspondence should be sent: Agricultural and Food Engineering Division, Asian Institute of Technology, GPO 2754, Bangkok, 10501, Thailand.

Journal of Food Quality 16 (1993). 451-470. All Righfs Reserved. Topyright 1994 by Food & Nutrition Press, Inc., Trumbull, Connecticut. 45 1

452 S. ILANGANTILEKE, C. KARUNARATNE and M. SENANAYAKE

world supply of true cardamom comes mainly from Malabar, Bangalore, Mysore and Sri Lanka. These countries have commercially supplied, both to the domestic and export markets, cardamom as either bleached, semi-bleached, deconicated and ground products to be used as spices for flavoring in cookery, the baked food industry and in beverages.

The quality of the processed product is important to meet the export market standards to which cardamoms are supplied by the producing countries. Quality assessment is primarily based on three major characteristics, appearance, aroma/flavor and strength of the volatile oil.

Optimum appearance is judged by the final "parrot green" color of the cardamom that is obtained after drying. Color is therefore an important grading parameter in trade and determines the market price to a great extent. Fading of the green capsule color caused by improper drying and processing is identified closely with the deterioration in flavor strength, caused by the evaporation of volatile oil (Purseglove et aZ. 1988). Therefore these quality parameters are interrelated.

The color of the capsule is due to the chemistry of the pigments present; the major pigment is chlorophyll. Color fading is thought to be analogous to that of peas and other green vegetables where the magnesium ion of the chlorophyll molecule is substituted by hydrogen ions, donated by organic ions present in the capsule, which results in an irreversible conversion to pheophytin (Cenkowski ef al. 1989).

Differences between the volatile-oil compositions of Malabar-type and Mysore-type cardamoms have been studied by Lewis et al. (1966), using distilled oils, and by Bernhard et al. (1971), using cold-pressed oils. The results indicate that the difference in oil composition between Malabar and Mysore cardamoms is quite quantitative rather than qualitative. The major components of cardamom oils are 1 ,8-cineole (20-60%) and alpha-terpinyl acetate (20-53 %). The content and organoleptic character of the volatile oil, and the color of the fruit at harvest and its capacity for conversion into the dried, green form are primarily dependent upon the cultivar grown and the processing conditions (Purseglove el al. 1988).

Drying is a major operation in the processing of cardamom capsules. Drying is done to avoid mold formation, which results in skin blemishes that effect appearance. At harvest, the capsules have a moisture content of about 75% which is reduced to less than 13% for safe storage. Cardamom is traditionally dried in the sun or in artificial driers with very limited control of processing parameters, resulting in poor quality product.

Studies on the effect of processing parameters on cardamom, specifically those that affect quality are limited.

Natarajan er al. (1963) found that soaking the capsules in 2% sodium carbonate for 10 min prior to drying inhibited color loss during drying and

TREATMENT EFFECTS ON CARDAMOM QUALITY 453

extended color retention during storage. Further studies to determine the effect of combining the predrying treatment with varying drying temperatures are necessary to produce cardamom with quality conforming to the standards of importing countries. The overall objective of this study therefore was to investigate the effect of predrying treatment and drying temperatures on the market quality of cardamom.

MATERIALS AND METHODS

The Malabar type Ceylon variety grown in Rattota/Gammaduwa area in the hill country of Sri Lanka was used in this study. The samples were collected after full maturity and uniformity in size was attained. The correct stage of maturity for harvest was when the capsules started turning yellow and the seeds inside changed from brown to a black color.

Re-Drying Treatment

The predrying conditions used in this study were a control with no chemical treatment (untreated) and a chemical treatment. The cardamom samples each of 6 kg (fresh weight), were dipped in a 2% sodium carbonate-in-water solution for a period of ten minutes. The treatment was based on a similar study for retention of green color in cardamom conducted by Natarajan ef al. (1968).

Drying of Cardamoms

A Kilburn Tray dryer having dimensions of 195 * 100 * 185 cm was used to study the effect of drying parameters on the quality of the processed cardamoms. The dryer had a capacity of 48 trays 80 * 40 * 30 cm. Trays were made of 18 gauge aluminum sheets, suitable for trolley loading. The dryer was a cross-flow type fitted with a 1 hp fan which gave even temperatures and uniform air movement at every drying tray level; thus, subjecting the product to uniform drying.

The intake of fresh air and the release of humidity were controlled by manually operated dampers. Tubular heaters with suitable loading for working temperatures up to lOOC, 200C and 300C were used to heat the air in the drier. The drying air temperature was indicated by a dial thermometer and controlled by a safety thermostat with an accuracy of +/- 5C over the full range. During experimentation, a wet and dry bulb thermometer was placed inside the oven and the relative humidity was regularly determined throughout the drying duration.

Both chemically treated and untreated cardamoms were dried under six sets of conditions to determine the effect of air temperature and drying rate (moisture


gradient) on quality attributes. Temperature was controlled at 35, 45 and 55C, and drying was accomplished either continuously or in a two-step process. For continuous drying, the cardamoms were exposed to the heated air until the moisture content was reduced to approximately 10%. For two-stage drying, 1 kilogram of sample was separated from the continuous drying cardamoms when the moisture content was reduced to approximately 20%. The following day, the 20% moisture cardamoms were further dried to approximately 10% moisture. The introduction of a lag period on each treatment was based on a study done by Rijk and Dunovan (1981), who indicated that a high moisture content of about 80% combined with a high drying temperature, resulted in a steep moisture gradient from the core to the periphery of the fruit. To avoid the moisture gradient, a drying temperature of less than 55C and intermittent drying was recommended and was found to have an effect on the chemical as well as physical appearance of cardamom. A preliminary trial was conducted to determine the time to reduce the moisture content to the 10 or 20% level. The moisture content was estimated by the Toluene Distillation Apparatus (A.O.A.C. 1990).

Determination of Cardamom Quality

The dried cardamoms were subjected to physical and chemical analysis as described below. The chlorophyll content was analyzed at five intervals during drying.

Spectrophotometric Analysis for Chlorophyll. Chlorophyll was determined by the standard method practiced at the Research Station of the Department of Export Crops, Matale, Sri Lanka. The method was based on the work of Leo, (1 960) and determines chlorophyll a and b together with phecophytins in Sri Lankan cardamoms.

Procedure for Uncured Cardamom. Known weights at different stages of drying were measured for partially dried cardamom. The samples were transferred with about 15 ml of 90% acetone into a macerator vessel. Macera- tion was done at medium speed for two minutes. The sample was placed into a mortar and ground with a pestle until no thick pieces of cardamom were left. On occasions where the tissue was particularly resilient a small amount of washed sand was added into the mortar. Next, the sample was transferred into a wide mouth column in which a cotton plug had been placed over the scinter base. The macerator vessel, the mortar and pestle were thoroughly washed with 90% acetone and the solution added into the column. The column was covered with aluminum foil and left for 30 min.


During the analysis, into one of two 25 ml standard flasks 2 ml of 90% acetone was added. To the other flask, 2 ml of the oxalic acid solution was added. Light was excluded from both flasks and the liquid in the flasks were made up to the mark with the extracted stock solution. The absorbance of solution in the first flask was measured in 1 cm cells in the visible range by a Spectronic 21 spectrophotometer at 645 and 662 nm. Similarly, the second solution was kept in the dark for 4 h and the absorbance was measured at 645, 655, 662 and 666 nm.

Procedure for Cardamoms Being Dried. The analysis was done by method described above, but by using 85% acetone throughout (Leo, 1960).

Procedure for Cured Cardamom. A similar analysis was done for the cured cardamoms by taking 2-4 g of capsules without grinding. The experimental procedure was the same as above. The acetone used was of 80% concentration since this concentration was considered sufficient to dissolve chlorophyll found in the dried capsule. The total chlorophyll as a percentage and the total chlorophyll in mg/g on a moisture free basis was then calculated.

Color Determination by Photoelectric Reflection. The color of the berries before and after drying was determined by using a photoelectric reflection meter with the green tristimulus filter as recommended by Natarajan et al. (1968). The Y values for both treated and untreated cardamoms were measured at each point where moisture was also being determined for each drying temperature.

Volatile Oil Content and Composition. The volatile oil content was determined before drying, during drying and immediately after drying by the modified Clevenger method specified for the detection of water insoluble steam volatile oil (A.O.A.C. 1990). A sample sufficient to yield 2-5 ml of oil was weighed and carefully transferred to a short neck round bottom flask with a S.T 24/40 ground joint, 500 ml of water was added and the apparatus was assembled using a Clevenger trap.

The flask was heated and the solution was stirred maintaining a distillation rate of 1 to 2 drops per second. The distillation was done by a condenser 400 mm in length, with a water-cooled drip tip until two consecutive readings taken at one hour intervals showed no difference in oil volume in the trap. The sample was cooled to room temperature and allowed to stand until the oil layer was clear. The volume of oil collected was read, estimating to the nearest 0.02 ml.

The oil of the chemically treated and untreated cardamom were qualitatively analyzed by G.L.C. The extracted oil was analyzed both before and after drying by gas chromatography in order to differentiate the presence of volatile components at varying temperature levels.

45 6 S. ILANGANTILEKE, C. KARUNARATNE and M. SENANAYAKE

A Shimatsu C-R 5A instrument, with a flame ionization detector connected to a strip chart recorder through a computing integrator was used for the analysis. The recorder sensitivity was kept at 3 mV and the chart speed was adjusted to 2 mm/min. The column used was stainless steel, 3 m long and 3mm in diameter, packed with OV 101 (Dimethyl silicone having an approximate molecular weight of 30,000) on 80/100 Supelcoport. Helium carrier gas of 30 ml per min and hydrogen and air flow 25 ml per min and 275 ml per min, respectively, were used. the injector block and detector temperature were 225C and 250C, respectively. The column oven was programmed from 60-200C at 4C per min and held for 30 min. When the samples were injected, 1 micro-liter of the oil was diluted with 1 ml of acetone; 0.1 micro-liter of the mixture was injected.

Initially, authenticated samples were subjected to gas chromatography after being diluted in the same proportion. This was done so that the relative retention times of these samples in relation to the solvent (acetone) could be identified. Emphasis was made on the 1,8 cineole as well as the alpha terpinyl acetate contents of the sample, since these were the predominant compounds governing the organoleptic properties, imparting a relatively harsh flavor (Brennard and Heinz 1970).

Physical Characteristics

Bulk Density. The bulk density was determined at the seven drying stages by placing a 50g sample in a 100 ml volumetric flask. The balance volume was made up with distilled water using a burette. The bulk density was expressed in gramicubic centimeter for three replicates. Corrections were made to compen- sate for moisture depletion throughout the drying.

Spilt Weight Percentage. The shrivelled and split capsules were weighed and expressed as a percentage of the original weight at various stages of drying.

Percentage Out-Turn. The percentage out-turn was defined as the dry weight of seeds obtained at unit fresh weight of sample as described by Sarathkumara et af. (1985). The cardamoms exposed to different temperature conditions were separately assessed by taking three 50 g samples as replicates for each of the five readings.

Gradewise Differentiation. After the drying was terminated, 500 g samples were separated into commercially accepted grades, LG (Lanka green), LLGl (Lanka light green :), LLG2 (Lanka light green 2), LB (pale buff) and LNS (Off color or Lanka nonspecific) and percentages determined.

TREATMENT EFFECTS ON CARDAMOM QUALITY

-0- Tamprratura 55 "c - t 3 Tamparatun 45"c

I Tampwaturr 35"c

-o- lag at 55"c

I)- lag at 45 "c - + lag at 35 "c

457

-

-

RESULTS AND DISCUSSION

Quality Analysis of Treated Cardamom Residual Chlorophyll

18

16

14

12

10

8

b b 0 5 10 15 20 25 30 35 40

I ime (in Hrs.)

FIG. 1. CHANGE IN % RESIDUAL CHLOROPHYLL WITH DRYING TIME FOR CHEMICALLY TREATED CARDAMOM

Chemical Characters as Effected by the Drying Process

The Effect of Drying on Chlorophyll Content.

Spectrophotometric Analysis. The results in Fig. 1 and 2, indicate a sharp decline in percentage chlorophyll in the capsules during the first three hours of drying. The average loss of chlorophyll in the sodium carbonate treated cardamom at drying temperatures of 35 and 55C were 87% and 90%, respectively. For the untreated capsules, the chlorophyll reduction was 91 % and 92 % , respectively.

Figures 1 and 2 show that the degradation of chlorophyll in the untreated sample was greater than in the chemically treated sample for each drying condition. The results of Duncan's Multiple Range Test (D.M.R.T) done to analyze significant differences in chlorophyll contents of cardamoms exposed to varying temperature levels are given in Table 1. Statistical analysis shows that the highest mean chlorophyll retention was in the continuously dried chemically treated cardamom at 45C and that there was no significant difference between continuously dried cardamom at drying temperatures of 45C and 35C, respectively. There was no significant difference between the 35C continuous sample and the 45C continuously dried sample. However, there was a significant

\ \ b Lagged Period

6

b 7 I I 1 I I I I I -

difference in chlorophyll depletion between drying temperatures of 55C and 35c.

These differences in discoloration may be a result of elevated heat treatment which catalyzes the rapid conversion of chlorophyll molecule to pheophytin. The maximum chlorophyll retention for the untreated samples was in samples dried at 35 and 45C.

There was a significant difference in chlorophyll content between chemically treated, continuously dried samples at 35,45, 55C and with those that were not chemically treated. The highest quantity of chlorophyll in these samples was 0.0069 mg/g. However, in the untreated samples, the continuously dried samples at 45C, yielded the highest chlorophyll content of 0.0058 mg/g. Of the chemically treated cardamoms dried at 35 and 45C, the drying temperature of 45C could be considered suitable for drying in relation to the maximum chlorophyll retention. Drying at this temperature was only 11 h as against 12 h for 35C.

The retention of chlorophyll in the chemically treated cardamom could be due to the rapid removal of moisture when the waxy layer on the top of the capsules are removed by the sodium carbonate treatment. In the drying of canola seed, Cenkowski et al. (1989) found that chlorophyll compounds, such as pheophytins which are present in the bottom layers of capsules, tend to degrade due to oxidation when exposed to prolonged heat treatments. This behavior was significant at the higher temperature of 55C during the drying of cardamom in this study.


Oil (ml/gm)

0.05'

0.06b 0.07'

0.07' 0.07'

0.07'

TABLE 1. SUMMARY OF STATISTICAL ANALYSIS FOR TREATED AND UNTREATED

CARDAMOM CAPSULES. (Columns analysed by DMRT).

Photoelect. (Y value)

19.2'

20. l b 15.2'

16.0d 16.9'

17.0"

TREATED Chlorophyll (mg/gm)

0.0064'

0.0054' 0.0069"

0.005 gb 0.006F

0.0060b

55°C continuous

55°C lag drying 45°C continuous

drying

Splits (%pods )

6.33d

7.00' 4.00'

4.66b 4.67b

5.33'

Volume per unit dry matter (cm'3/gm)

drying 45°C lag drying 35°C continuous

35°C lag drying

UNTREATED

drying

0 .W

1.09b 1. 1tid

1.27'

1.09b 1.05'

55°C continuous



drying

drying

drying 35°C lag drying

0.90a 0.05' 21.20'

1. lob 0.06b 23.20b 1. 13b 0.07' 16.00'

1.09b 0.07' 17. lod 1.23' 0.07' 17. 13d

1 .23' i8.00" 0.07'

0.0049b

0.0047b 0.0058'

0.0052' 0.0055'

0.0057'

6.00b

6.67b 2.00'

2.33' 4.33'

4.67' I

** Values having same superscripts are not significantly different to one another.

Photoelectric Reflection Meter. The Y values determined by the TC-p3 reflection meter are shown in Fig. 3. The results show that the samples having the lowest reflection value, (Y) of 15.2, had the highest chlorophyll content when compared with the % residual chlorophyll for the different treatments. Commercial acceptance is for a Y value below 17.5 (Natarajan ef al. 1968). All chemically treated samples dried at 35 and 45C showed desirable commercial color. However, in untreated cardamom, this value was achieved only for the 45C drying treatment.


Commrr -1

17.5

pcial Standard

Typ. of drying

= Undrid cotdamon mr! Continuous/laq 55 "C a Continuour/ taq 4 5 ' ~ a Continuour /lag 35 "C

FIG. 3. Y VALUES OF THE PHOTO ELECTRIC REFLECTION METER IIN MEASURING TREATED CARDAMOM

At higher temperatures, the increase in Y value signifies a decrease in chlorophyll and therefore treatments resulting in Y values higher than 17.5 would have capsules which will not be accepted commercially as high value products. Results of statistical analysis in Table 1. illustrates that at a drying temperature of 55C, the chlorophyll content was significantly different from that of the other temperatures, based on the Y values obtained.

A significantly low Y value of 15.2 was obtained at a drying temperature of 45C, for chemically treated cardamom subjected to continuous drying. However, the Y values of treated, untreated and lag dried cardamom at a drying temperature of 35C, were not significantly different.

The Effect of Drying on Oil Content. The oil collected after steam distillation was expressed as the oil content per unit dry weight of treated sample. The time taken for the oil depletion ranged from 7 to 12 h for the three temperatures. Exposure to a high temperature results in a loss of highly volatile terpenoids in the oil, thus decreasing the total oil content. The change in oil content with moisture content of capsules is shown in Fig. 4. The differences in oil content between the treated and untreated cardamom after final drying were 7.4%, 1.02% and 3.47% at drying temperatures of 35, 45, 55C respectively.

TREATMENT EFFECTS ON CARDAMOM QUALITY 46 1

Oil/dry mottor

0

0.08

0.06

0.04

0.02

0

FIG. 4. CHANGE IN OIL CONTENT WITH MOISTURE CONTENT IN CHEMICALLY TREATED CARDAMOM

The results in Table 1 indicate that there is a significant depletion of oil content of the cardamoms exposed to a high temperature. However, the depletion in oil content in the lag and continuously dried, treated and untreated cardamom was not significantly different at 45C and 35C. The depletion in oil content at a temperature of 55C, under continuous and lag drying was significantly different for both chemically treated and untreated cardamom.

Similar results were obtained by Mathai (1985), where volatile oil of chemically treated cardamoms, subjected to elevated drying temperatures showed a depletion in the total volatile oil content as a result of prolonged drying.

G.L.C Analysis to Detect Terpenoids. Eight terpenoids of importance were detected in the oils analyzed by G.L.C, utilizing standard samples of respective oils.

The relative composition of terpenoids present in 0.1 micro-liter of cardamom oil from capsules subjected to different drying treatments are shown in Fig. 5 and 6. The flavor and aroma of cardamom is governed mainly by 1-8 cineole and alpha terpinyl acetate contents. Purseglove et al. (1988) reported the presence of these compounds on a percentage basis can be a good indicator of

462 S. ILANGANTILEKE, C . KARUNAMTNE and M. SENANAYAKE

the harsh aroma and flavor of the cardamom. The percentage of flavor and aroma compounds of the chemically treated and untreated cardamom dried at a temperature of 45C, were 45.0% and 57.1 %, respectively. Similarly, the percentages of these two compounds for treated and untreated cardamoms, dried at 35C were 43.7% and 55.0%, respectively.

Although there was no significant difference in terpenoids under both conditions, cardamom dried at 45C can be regarded as most acceptable, considering the decrease in drying by 1 h, when compared with a drying temperature of 35C. Many of the terpenoids such as borneol and alpha pinene were found in minute quantities or were not present at all in temperatures over 45C. The highest concentrations of terpenoids were detected at 35C.

n

\ RETENTION TIME Imlnl TYPE

@ 20.353 a - Plnana E d

d

@ 22.217 M y r e m a

@ 23.815 p-Cymene

@ 24.421 I-8Clnaola

@ 28.82 Llnalool

@ 3 0 . 5 4 2 Bornaol

@ 30.937 -Tarplnaol

CONCENTRATION

0 4 2 3 4 %

1.890 Ye

1.856 %

47.18%

11.10%

2.381%

6. I6 I %

@ 36.879 U - Tarplnyl Acalala 19.273 '/o

L

FIG. 5 . GAS LIQUID CHROMATOPAC OF CARDAMOM OIL BEFORE DRYING (Not to Scale)


O,G Concentration

C5 = Continuous drying C7 = Lagged drying

8o t 6 0

40

20

n - S / C 5 55/C7 4!5/C3 4cI/C7 35/C5 35/C? Normal

Type of terpenoid

Cineole hzs TerpAct. a Linalool tzzd Myrcone Cymme a-pinrne Borneo1 rm] s-lbrpineol

FIG. 6. DISTRIBUTION OF TERPENOID IN CARDAMOM OIL EXTRACTED FROM CHEMICALLY TREATED CARDAMOM

A similar study done by Brennard and Heinz (1970) indicated that changes occurring in relative concentrations of chemical constituents under each drying treatment can be expected in cardamom since the volatile oils which are responsible for the flavor of this spice consist largely of terpenoids. Terpenoids are generally unstable in the presence of acid, light, oxygen or heat, and are capable of undergoing hydrolysis, rearrangement, polymerization and oxidative reactions. Further, it has been observed that the differences in total oil content observed during heat treatment were apparently due to chemical changes rather than to evaporation. Rathnawathie (1986) illustrated the structure of some of these compounds, which are polymeric in nature and have the same molecular weight.

The changes in oil composition in the samples could be explained by the possible changes in structure of the chemicals influenced by elevated temperatures. The decrease in oil content for each treatment condition could be explained as the differences due to cumulative effects of both oxidation and evaporation.


Physical Characteristics of the Dried Cardamom

Change in Volume. Figure 7 illustrates the changes in volume or volume shrinkage of capsules with time, for cardamom dried under the three different drying conditions. The shrinkage of capsules at 55C was 0.083 cm3 per h, for treated cardamom, while for the untreated type the shrinkage was 0.0555 cm3 per h. Similarly, the shrinkage at a drying temperature of 45C for treated and untreated cardamom were 0.0373 and 0.0328 cm3, respectively. The higher shrinkage in the chemically treated cardamom, was possibly due to the rapid moisture removal in capsules that had their surface coating removed with chemical treatment.

Although a commercial standard or a reasonable guide for the final acceptable volume of capsules after drying is not available, a medium size capsule is considered to be most suitable. Mathai (1985) states that the grades with heavier and bigger capsules were inferior in flavor constituents to that of medium grades. Therefore, the use of a medium grade as standard for quality selection based on volume change may be suitable for trade.

3 Volume(cm 1 1.5

I .2

0.9 Lagged Period

0.6

0.3

0 I I I I I I 1

0 5 10 I5 20 25 30 35 40 Time (in Hrs.)

-0- Tomporoturo 55% 6 Tomporoturo 46% t Tompomturr 35 % + lag at 55"c + lag at45Oc + lag at 35

FIG. 7. CHANGE IN CAPSULE VOLUME WITH DRYING TIME IN CHEMICALLY TREATED CARDAMOM


Thus, a larger change in volume of the treated or untreated cardamom at a drying temperature of 45C, compared to that at 55C, could be considered acceptable commercially. The average acceptable volume therefore could be taken as 1.04 cm3.

The volumes of treated cardamoms exposed to a lag period were 1.09, 1.09, I .27 cm3, respectively, while the corresponding volumes of the continuously dried sample were 0.85, 1.02 and 1 . I6 cm3 at 55, 45, 35C drying temperatures, respectively. Lag dried cardamoms had a relatively larger volume, possibly because the capsules were not exposed to continuous high heat in the drying chamber, thus decreasing the excessive shrinkage of capsules. The highest mean capsule volume was obtained at a drying temperature of 35C for chemically treated cardamom under lagged drying.

A D.M.R.T done to test the effects of different drying and predrying conditions on volume change, indicated that the mean volume change at 35C for the chemically treated sample dried with a lag period, was significantly different from volume changes obtained from all other treatments at a 95% confidence level, Table 1. There was no difference between the mean volumes obtained for both chemically treated and untreated cardamom at 45C and 55C, during lagged drying. Of all treatments, studied, a medium volume change was obtained for the continuously dried sample at a drying temperature of 45C.

Split Weight Percentage as Effected by Drying Conditions. The change in percentage of shrivelled and split capsules with drying time is seen in Fig. 8 . At 55C, both chemically treated and untreated cardamoms had 6% splits. Since the accepted percentage of splits for the Sri Lankan type cardamom is five out of a hundred, 1 % extra splits is in excess of the accepted standard.

However, at 45C both continuous and lag dried chemically treated cardamoms had an average of 4.0% and 4.70% splits, while in untreated cardamoms, the splits were lower and were 2.0% and 2.33%, respectively. The chemically treated cardamom had a higher % splits when compared with the untreated cardamoms. The cardamoms that were subjected to a lag treatment had a higher % splits in comparison with that which was continuously dried. The percentage of splits due to a drying temperature of 45C for the untreated sample was significantly higher than that which was dried in 45C and were 4.67% and 4.33%, respectively. The increase in percentage splits could have been due to the prolonged heat exposure of capsules. However, the % splits obtained on each treatment at these two temperatures were below the accepted market standard of 5 % .

Statistical analysis, shown in Table 1, further illustrates that there is a significant difference in the % splits for untreated cardamom at 45C, when compared with the chemically treated cardamom at the same temperature.


"/o Splits I I 1 I I I I I

6 P Lagged Period

4

2

0 5 10 IS 20 25 30 35 40

Kme (in Hrs. )

-0- Tempomturr 5S "c -0- Temporoture 45 % -+- Tompomtura 35 "c lag at 55 "c + lag at 45 "c + lag at 35 "G

FIG. 8 . CHANGE IN CAPSULE SPLITS WITH DRYING TIME FOR TREATED CARDAMOM

Out-Turn Percentage as Effected by Drying Conditions. The percent out-turn of the cardamoms exposed to different temperatures was similar since all cardamoms were dried until a final moisture content of 10%. However, when samples were withdrawn during drying, the chemically treated cardamoms had a low out-turn possibly due to faster drying. The chemically treated and untreated cardamom, dried for 6 h, had out-turns of 63.4% and 65.3%, respectively. Similarly, cardamoms that reached a safe storage moisture content of 10% had an out-turn between 31.34 or 33.34, which could be accepted as a standard for the export market (Pruthi 1984).

Gradewise Differentiation. Percentages of the different grades obtained for the different treatments are classified in Table 2 according to the Sri Lankan export grade standards. The results indicate that the percentages of LG and LLGl in chemically treated cardamom dried at 45C accumulated to 64.6%, while those that were not treated were 49.1 %. However, at 35C for both chemically treated and untreated cardamoms, the percentages of LG and LLG 1 were 50.5 % and 49.5 %, respectively.

TREATMENT EFFECTS ON CARDAMOM QUALITY

21.2 % 25.27 % 19.63 % 28.61 % 2.26 %

19.3 % 21.33 % 27.58 % 29.8 % 3.96 %

467

LG LLGl LLG2 LB LNS

LG LLGl LLGZ LB LNS

Cont.

Lag

Cont.

Lag

Cont.

Lag

29.19 % 19.88 % 38.41 % 6.54 % 5.96 %

19.13 % 22.89 % 43.32 % 8.87 % 5.7 %

untreated

TABLE 2. GRADE-WISE DIFFERENTIATION OF CARDAMOM

SUBJECT TO VARYING DRYING CONDITIONS

I

LG LLGl LLG2 LB LNS

LG LLGl LLG2 LB LNS

55°C

35°C

18.48 % 19.51 % 30.64 % 18.52 % 12.85 %

LG LLG 1 LLG2 LB LNS

LG LLG 1 LLG2 LB . LNS

LG LLGl LLG2 LB LNS

45°C

82.6 64. I6 160 60.2 33.04

22.92 58.04

200.04 20.4 48.52



20.65 % 16.04 % 40.00 % 15.05 % 8.26 %

18.23 % 14.51 % 50.01 % 5.10 % 12.13 %

55°C

LG LLG 1 LLGZ LB LNS

LG LLG 1 LLGZ LB LNS

Chemically untreated I 35°C

84.81 113.1 78.55 114.45

9.072

69.23 85.35 110.34 119.2 15.851

Chemically untreated I 45°C

116.67 79.52 153.67 26.19 23.84

76.54 91.58 173.3 35.48 23.08

Chemically

73.92 78.04 122.56 74.08 51.4

65.54 94.04 114.04 73.28 52.84

I

28.51 % 18.32 %

Chemically

130.37 71.48 102.61 77.8 17.72

80. I 1 123.67 88.94 85.46 21.65

treated

32.59 % 17.87 % 25.65 % 19.45 % 4.43 %

20.04 % 30.93 % 22.23 % 21.36 % 5.41 %

Chemically treated

168.71 89.61 32.98 91.95 16.731

78.24 137.27 94.46 66.173 23.838

42.17 % 22.40 % 8.24 %

22.98 % 4.18 %

19.56 % 34.31 % 23.61 % 16.54 % 5.95 %

Chemically treated

468 S. ILANGANTILEKE, C. KARUNARATNE and M . SENANAYAKE

Since grading by this method is purely by visual observations and therefore on appearance, drying at 45C and 35C were observed to have yielded the best capsules, classified as LG and LLG1, when compared with all other drying treatments.

CONCLUSIONS

(1) Cardamoms subjected to chemical treatment at 35 and 45C drying temperatures had residual chlorophyll contents of 11.0% and 10.9%, respectively, after 12 and 11 h of drying down to a moisture content of 10%. Tempera- tures of 45 to 35C were found to give a better chlorophyll retention in the chemically treated capsules.

(2) The most desirable Y values of 15.2 and 16 were obtained for the chemically treated cardamom, dried at 45C under continuous and lag drying, respectively. The value at 45C for continuous drying, could be considered in close comparison to the Y value of 10.2, obtained for cardamoms before drying.

(3) The difference in total oil content of treated and untreated cardamoms at 45 and 35C was not significant, although the decrease in oil at 55C was significant.

(4) The G.L.C analysis showed that the treated cardamoms continuously dried at 45C had 45% of 1-8 cineole and alpha terpinyl acetate when compared with 57.1% obtained for the untreated cardamom dried at 45C. The maximum retention of terpenoids were found in the untreated cardamom dried at 45C.

(5) The mean volume of 1.04 cm3 attained by drying chemically treated and untreated cardamom samples at 45C may be accepted as most suitable to meet commercial standards.

(6) The untreated sample dried at 45C had 2 - 2.3% of splits. The samples other than those subjected to 55C were well within the specified limits of 5% in commerce.

(7) The chemically treated cardamom dried at 45C had a maximum of 42.2% of the LG grade, which is considered to be the superior grade in the cardamom trade. The chemically treated samples continuously dried at a temperature of 35C, had 32.6% of the same grade.


(8) The results of the study have shown that chemical pre-treatment with 2% sodium carbonate prior to drying in combination with a drying temperature of 45C were found to provide ideal conditions to obtain the quality stipulated for the export markets.

ACKNOWLEDGMENTS

The authors wish to acknowledge the assistance provided by the staff of the Export Agricultural Department of the Ministry of Agriculture, the Institute for Fundamental Studies in Kandy . the Perennial Crops Development Project of the Ministry of Agriculture, all in Sri Lanka, as well as the Asian Institute of Technology in Bangkok. Their assistance was valuable for the completion of this project.

REFERENCES

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EFFECTS OF CHEMICAL PRETREATMENT AND DRYING TEMPERATURES ON THE COMMERCIAL QUALITY OF CARDAMOM...

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