studies on drying of bitter gourd slices in
TRANSCRIPT
STUDIES ON DRYING OF BITTER
GOURD SLICES IN MICROWAVE
ASSISTED FLUIDIZED BED DRYER
Presented by
SHAHWAR SIDDIQUI
M.Tech IV sem (APFE)
Under The Supervision
Of
Dr. MOHAMMAD ALI KHAN
(Associate professor)
INTRODUCTION
Momordica charantia Linn. commonly known asBitter melon or Bitter gourd is tropical andsubtropical climber of the family Cucurbitaceae.
It is widely distributed in China, Malaysia, India
and tropical Africa.
In Ayurveda, various parts of Momordica charantia(Karela) are recommended for many diseases like;cholera, bronchitis, anaemia, ulcer,diarrhea,dysentery.
Bitter gourd contains an array of biologically active
plant chemicals including triterpene,proteins,
steroids, alkaloids, saponins, flavonoids and acids
due to which plant possesses anti-fungal, anti-
bacterial, anti-parasitic, anti-viral, anti-tumorous,
hypoglycemic and anti-carcinogenic properties.
BITTERGOURD CULTIVATION
Annual Bittergourd Cultivation in
ASIA
BOTANICAL CLASSIFICATION
Kingdom Plantae
Division Magnoliophyta
Class Magnoliosida
Order Violes
Family Cucurbitaceae
Genus Momordica
Species Charantia
GREEN FRUITS OF
DIFFERENT MOMORDICA
SPECIES.
BENEFITS OF BITTER GOURD
Bitter gourd is worldwide known for its
effectiveness in treating diabetes. Bitter gourd
chemically contains a compound that is very much
similar to insulin and sometimes also referred as p-
insulin.
Bitter gourd is also good digestive agent and helps
in stimulating the secretion of gastric juices. It is
very helpful in stimulating liver for secretion of bile
juices that are very essential for metabolism of fats.
THERAPEUTIC USES
Bitter gourd is an appetite stimulant. Hence it is
used in the treatment of anorexia, a disorder in
which a person is unable to eat the required amount
of food.
Bitter gourd is used as a blood purifier due to its
bitter tonic properties. It can heal boils and other
blood related problems that show up on the skin.
BITTER GOURD – Functional
Uses
OBJECTIVES
To study the effect of inlet air temp, inlet airvelocities and microwave powers on drying behaviorand quality attributes of bitter gourd.
To study color change kinetics of bitter gourd duringmicrowave assisted fluidized bed drying.
To determine the best mathematical model describingthe kinetics of the drying process.
To study the effect of MAFBD on drying kinetics ofbitter gourd.
Materials and Methods
RAW MATERIALS USED
Good quality, fresh bitter gourds which had similar
skin color were procured from the local market. The
damaged, infected ones were removed manually by
visual inspection.
After cleaning with tap water, wiping and slicing,
200g of fresh sample of bitter gourd was weighed
and subjected to drying in a laboratory microwave-
assisted fluidized bed dryer.
DETAILS OF PARAMETERS &
THEIR LEVELS USED IN MAFBD
OF BITTERGOURD
S.NO.Types of
parametersParameters Levels Description
1
Independent
drying
parameters
Inlet air
temperature
Inlet air
velocity
Microwave
power
3
3
3
50, 55 &600C
25,30&35 m/s
180, 360 &
540 W
2Measuring
parameters -------
Weighing of
sample at
every 5 min.
FLOW SHEET FOR MAFBD OF
BITTER GOURD
DETERMINATION OF
PROCESS PARAMETERS
COLOUR ANALYSIS
MATHEMATICAL
MODELLING
MAFBD DRYING DATA FITTED TO THE
FOLLOWING DRYING MODELS
S.No Name of Model Model Equation
1 Lewis Model M.R.=exp(-k*t)
2 Henderson & Pabis Model M.R= a*exp(-k*t)
3 Wang & Singh Model M.R= 1+a*t+b*t2
4Approximate Diffusion
Model
M.R=a*exp(-k*x)+(1-
a)*exp(-k*b*x)
5 Page model M.R=exp(-a*x^b)
VALIDITY OF MODELS
For MAFBD, lowest R2 value (0.90400) was obtained for
approximate diffusion model fitted to the drying condition:
55°C inlet air temperature, 25 m/s inlet air velocity and 540W
microwave power with the highest chi-square and RMSE
values (0.02901 and 0.12044, respectively) for sample 6.
The highest value of R2 (1.000) was obtained for Page model
fitted to the drying condition: 60°C inlet air temperature ,
35m/s inlet air velocity and microwave power of 540W,
which had lowest chi-square and RMSE values (1.02204E-
23 and 2.61029E-12 respectively) for sample 27. Thus Page
Model is the most acceptable one and fitted best to the given
set of experimental data for MAFBD.
EXEMPLARY FITTING CURVE
OF VARIOUS MODELS
EFFECTS OF MAFBD ON
MOISTURE CONTENT OF BITTER
GOURD
CHANGE IN MOISTURE CONTENT OF
BITTER GOURD SAMPLES DURING
DRYING
Average initial moisture content was 12.3015 (g of water/g of drymatter). Depending on the drying treatment, during MAFBD dryingat 25 m/s inlet air velocity, the final moisture content rangedbetween 0.1101-0.1834 in 45 -100 mins as the microwave powerlevels varied from 180W to 540W (Fig.4.1).
At 30 m/s inlet air velocity, the final moisture content rangedbetween 0.1170-0.1748 in 40-90 mins, when the microwave powerlevels varied from 180W to 540W (Fig. 4.2). Similarly, at 35 m/sinlet air temperature, the final moisture content ranged between0.1108-0.1684 in 30-80 mins, when the microwave power levelsvaried from 180W to 540W (Fig. 4.3).
Drying time progressively decreased with the increase in inlet air velocities from 25m/s to 35m/s at a given microwave power level and drying temperature. Hence above findings suggests that the applied inlet air velocities and drying air temperature had a crucial effect on the drying rate during MAFBD drying.
EFFECTS OF MAFB DRYING ON L
VALUES OF BITTER GOURD
SAMPLES
L values decreased with drying time. In general, L also decreasedwith an increase in microwave power as well as the inlet airtemperature.
At 25m/s, it could be seen that the average minimum reduction to39.3000 was observed at 360W, 55°C inlet air temperature andaverage maximum reduction to 37.3850 was observed at 540W and50°C inlet air temperature.
At 30 m/s, the average minimum reduction to 39.2600 was observedat 360W microwave power and 55°C inlet air temperature andaverage maximum reduction to 37.2950 was observed at 540Wmicrowave power and 50°C inlet air temperature.
At 35m/s, the average minimum reduction to 39.2525 was observedat 360W microwave power and 55°C inlet air temperature andaverage maximum reduction to 37.2500 was observed at 540Wmicrowave power and 50°C inlet air temperature. The decrease in Lduring drying followed exponential decay law with coefficient ofdetermination ranging between 0.9968 and 0.8627.
EFFECTS OF MAFB DRYING ON “-a*”
(GREENNESS) VALUES OF BITTER GOURD
SAMPLES
The initial color of samples showed a negative a
values ranging from -5.0200 to -7.0750 indicating
greenness while the final -a value varied from -
0.5200 to -1.9700 as the microwave power levels
were increased.
When the bitter gourd was dried by MAFBD at
varying temperatures (50°C, 55°C, 60°C), the
average minimum reduction to -0.52 in –a value
was observed at 180W microwave power, 50°C inlet
air temperature and 30m/s inlet air velocity whereas
the maximum reduction to -1.9700 was observed at
540W microwave power 60°C inlet air temperature
and 35m/s inlet air velocity. -a values also exhibited
exponential decay law with coefficient of
determination ranging between 0.9964 and 0.8417.
EFFECTS OF MAFB DRYING ON “b”
(YELLOWNESS) VALUES OF BITTER
GOURD SAMPLES
The b value in fresh samples ranged between 35.47 to 28.12. The bvalue decreased with the increase in drying time and also with theincrease in microwave power and inlet air temperature.
At 25m/s it could be seen that the average minimum reduction to25.1135 was observed at 360W microwave power and 60°C inlet airtemperature and average maximum reduction to 22.0300 was observedat 50°C inlet air temperature and 540W microwave power.
At 30m/s, the average minimum reduction to 25.1020 was observed at360W microwave power and 60°C inlet air temperature and averagemaximum reduction to 22.0150 was observed at 540W microwavepower and 55°C inlet air temperature.
At 35m/s, the average minimum reduction to 24.0142 was observed at360W microwave power and 50°C inlet air temperature and averagemaximum reduction to 22.0112 was observed at 540W microwavepower and 50°C inlet air temperature. b values also exhibitedexponential decay law with coefficient of determination rangingbetween 0.9949 and 0.8197.
EFFECT OF MAFB DRYING ON ∆E
VALUES OF BITTER GOURD
SAMPLES
At 25m/s inlet air velocity, it could be seen that the average minimumchange in color to 15.8215 was observed at 60°C inlet air temperatureand 540W microwave power also average maximum change in color to51.6622 was observed at 50°C , and 360W.
At 30m/s inlet air velocity , it could be seen that the average minimumchange in color to 15.1202 was observed at 60°C inlet air temperatureand 360W microwave power also average maximum change in color to24.5598 was observed at 55°C inlet air temperature and 180Wmicrowave power.
At 35m/s inlet air velocity , it could be seen that the averageminimum change in color to 6.3575 was observed at 60°C inlet airtemperature and 360W microwave power also average maximumchange in color to 24.4198 was observed at 50°C inlet airtemperature and 360W microwave power. The color change datawere fitted to exponential growth model with coefficient ofdetermination ranging between 0.9584 and 0.9999.
EFFECT OF MAFB DRYING ON
CHROMA VALUES OF BITTER
GOURD SAMPLES
At 25m/s inlet air velocity the average minimumchroma value reduced to 25.0574 was observed at60°C inlet air temperature and 360W microwavepower and average maximum chroma value reducedto 22.1853 was observed at 60°C inlet airtemperature and 540W microwave power.
At 30m/s inlet air velocity the average minimumchroma value reduced to 25.0186 was observed at60°C inlet air temperature and 360W microwavepower and average maximum chroma value reducedto 22.1551 was observed at 55°C inlet airtemperature and 540W microwave power.
At 35 m/s inlet air velocity the average minimumchroma value reduced to 23.8448 was observed at50°C inlet air temperature and 180W microwavepower and average maximum chroma value reducedto 22.1060 was observed at 60°C inlet airtemperature and 540W microwave power.
The exponential data on chroma were regressed toexponential decay model where the data reasonablyfit to the model and coefficient of determinationranged between 0.9955 and 0.8457.
EFECT OF MAFB DRYING ON HUE ANGLE
VALUES OF BITTER GOURD SAMPLES
At 25m/s inlet air velocity, it could be seen that the average
minimum reduction to 91.9246° was observed at 55°C inlet air
temperature and 180W microwave power and average maximum
reduction to 94.3865° was observed at 50°C inlet air temperature
and 360W microwave power.
At 30m/s (Fig.4.21) , it could be seen that the average minimum
reduction to 91.2888° was observed at 50°C inlet air temperature
and 180W microwave power and average maximum reduction to
94.2791° was observed at 60°C inlet air temperature and 540W
microwave power.
At 35m/s (Fig.4.22) , it could be seen that the average minimum
reduction to 91.1622° was observed at 60°C inlet air temperature
and 360W microwave power and average maximum reduction to
94.2386° was observed at 60°C inlet air temperature and 540W
microwave power.
ANOVA FOR THE EFFECT OF MAFBD
ON ASH CONTENT OF BITTER
GOURD
At 25m/s, the value of ash content decreased from 1.945 to 1.87when temperature increased from 50°C to 55°C at 360Wmicrowave power.
At 30m/s, the value of ash content decreased from 1.965 to 1.645when temperature increased from 50°C to 55°C at 180Wmicrowave power, also ash content decreased from 1.995 to 1.825when temperature increased from 50°C to 55°C at 360Wmicrowave power, so it was observed that ash content decreasedwith an increase in the temperature.
At 35m/s, the value of ash content decreased from 1.94 to 1.835when temperature increased from 50°C to 55°C at 180Wmicrowave power, also ash content decreased from 1.905 to 1.85when temperature increased from 50°C to 55°C at 540Wmicrowave power.
ANOVA FOR THE EFFECT OF MAFBD ON
REHYDRATION RATIO OF BITTER GOURD
It was observed that for the bitter melon dried by MAFBDmethod, at given temperature, the value of rehydration ratioincreased with the increase in microwave power and viceversa .
At 50°C inlet air temperature, rehydration value increased from4.527 (at 30m/s inlet air velocity & 180W microwave power to 5.37(at 35m/s inlet air velocity & 540W microwave power).
Similarly at 55°C inlet air temperature, rehydration value increasedfrom 4.49 (at 35m/s inlet air velocity & 360W microwave power to5.455 (at 25m/s inlet air velocity & 540W microwave power).
At 60°C inlet air temperature, rehydration value increased from4.44 (at 30m/s inlet air velocity & 180W microwave power to 5.15(at 25m/s inlet air velocity & 540W microwave power).
ANOVA FOR THE EFFECT OF MAFBD
ON VIT C OF BITTER GOURD
It can be inferred that both the inlet air temperature
and the microwave power level have significant
effect on the ascorbic acid content of the bitter
melon samples. The best ascorbic acid values
obtained in MAFBD were found at 540 MW and
60°C inlet air temperature for sample 27 which is
equal to 63.27 mg/ 100 g. The lowest value of
ascorbic acid value was obtained for sample 19 at
180 MW and 60°C inlet air temperature which is
equal to 45.54 mg/100 g.
Conclusion
Distinct differences were observed in dryingtimes according to the various conditionsapplied.
The shortest time was found for sample 27dried at 60°C inlet air temperature, 35/s inletair velocity, and 540W microwave power.
This sample also had the highest rehydrationvalue due to increased porosity of driedproduct at higher microwave power resultingin increased absorption of water duringrehydration.
Cont…
However, other factors, along with drying timeand rehydration ratio were considered in order toselect appropriate conditions for drying of bittergourd.
Judging by the color change and redness values,the sample dried at 60°C inlet air temperature,35m/s inlet air velocity, and 540W microwavepower had the least color change and the highestnegative “a” (greenness) value resulting in abetter quality product.
As this sample takes lesser time for drying byMAFBD, it resulted in better quality such as colorpreservation, higher Vit C content, and lessdestruction of the dried products.