DEVELOPMENT OF DEHUSKING TECHNOLOGY FOR PSYLLIUM (Plantago ovata) SEEDS 3785
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Date
2023-11
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jau junagadh
Abstract
Psyllium is a rich source of total dietary fibre and essential minerals like
calcium, potassium, and magnesium. It finds various applications in the food and
pharmaceutical industries, serving as a gluten substitute, thickening agent, and natural
fibre source due to its unique mucilaginous properties. However, processing psyllium
seeds poses challenges. Obtaining the desired husk yield requires multiple passes,
leading to high energy demands. There's a risk of husk fragmentation or turning it into
smaller particle size of husk, resulting in profit losses. Larger mesh-sized husks fetch
higher market prices. The research on effect of machine variations viz., feed rate, roller
clearance, roller speed ratio and seed moisture content on dehusking characteristics of
psyllium seeds and storage of psyllium husk in different packaging materials is limited.
The experiment was carried out in the Department of Processing and Food
Engineering, College of Agricultural Engineering and Technology, Junagadh
Agricultural University, Junagadh during the year 2022-23. The physical properties of
three different varieties of psyllium seeds viz., VI-1, GI-3 and HI-5 were evaluated at
three different moisture content from 6%, 12% and 18%. The geometric properties
length, width, thickness, size and sphericity were varied among different moisture
content and varieties from 2.52 mm to 2.81 mm, 1.25 mm to 1.48 mm, 0.72 mm to 0.80
mm, 1.33 mm to 1.47 mm and 0.513 to 0.533, respectively. The bulk density, true
density and porosity were varied from 550.07 kg/m3
to 585.54 kg/m3
, 1206.78 kg/m3
to
1316.84 kg/m3
and 54.06% to 56.75%, respectively. Static angle of repose was varied
from 28.07° to 35.99°. Coefficient of static friction on glass, plywood and GI sheet
were varied from 0.42 to 0.51, 0.47 to 0.52 and 0.48 to 0.55. Thousand seed weight of
psyllium varied from 1.52 g to 1.82 g. Terminal velocity of psyllium seeds was varied
from 2.63 m/s to 4.17 m/s.
The biochemical properties of psyllium husk and seeds of VI-1 variety was also
evaluated. The mean values of moisture content, total carbohydrate, crude fibre, true
protein, total fat, total ash and acid insoluble ash of psyllium seeds were 10.02%,
62.70%, 34.13%, 14.42%, 2.01%, 3.35% and 0.73%, respectively. The mean values of
moisture content, total carbohydrate, crude fibre, total dietary fibre, true protein, total
fat, total ash and acid insoluble ash of psyllium husk was 11.26%, 80.14%, 3.50%,
75.22%, 3.10%, 1.63%, 2.44% and 0.67%, respectively.
The dehusking technology based on rubber roller dehusking mechanism was
developed considering the measured physical properties of psyllium seeds. The major
components of developed dehusking technology were feed hopper with adjustable feed
ii
plate and slit, dehusking chamber consists of feed roller and rubber roller, constant
speed slow roller with adjustable clearance mechanism, fast roller with adjustable
differential speed between rollers. The separation of husk from dehusked seeds was
done by cyclone separation. The estimated cost of developed dehusking technology was
worked out to be ₹ 97,500. The performance evaluation of developed dehusking
technology was evaluated on the basis the different machine parameters viz., feed rate
(40, 50 and 60 kg/h), roller clearance (0.5, 0.6 and 0.7 mm) and roller speed ratio (1:1,
1.25:1 and 1.5:1) as well as different moisture content of psyllium seeds (6%, 9%, 12%,
15% and 18% w.b.).
The variation of different machine parameters varied the moisture content, total
carbohydrate, true protein, total fat from 10.06% to 11.41% (w.b.), 76.39% to 80.45%,
3.00% to 3.93% and 1.28% to 1.86%, respectively. The crude fibre, total dietary fibre,
total ash, acid insoluble ash, swelling volume of psyllium husk were varied from 3.16%
to 4.70%, 74.09% to 76.73%, 1.91% to 2.90%, 0.12% to 0.76% and 38.74 ml/g to 43.37
ml/g. The whole husk, average particle size, fineness modulus of husk, dehusking
efficiency of machine were varied from 52.31% to 80.65%, 302.42 μm to 393.49 μm,
2.59 to 3.43 and 64.16% to 90.85%. The husk yield, number of passes, dehusking time,
dehusking capacity and power consumption was varied from 215.46 g to 348.80 g, 19
to 59, 19.43 min to 61.02 min, 0.99 kg/h to 3.11 kg/h and 0.23 kWh to 0.88 kWh.
Dehusking at 40 kg/h feed rate, 0.5 mm roller clearance and 1.5:1 speed ratio was best
treatment combination among different treatment combinations.
For standardization of product parameter of developed dehusking machine, the
moisture content of seeds was varied from 6% to 18% (w.b.). This caused variation in
moisture content, total carbohydrate, true protein and total fat of psyllium husk from
5.49% to 13.94%, 77.73% to 82.74% to, 3.01% to 4.16%, 0.96% to 1.30%. Crude fibre,
total dietary fibre, total ash, acid insoluble ash, and swelling volume were also varied
from 3.87% to 4.04%, 75.50% to 77.12%, 1.88% to 2.44%, 0.16% to 0.78% and 40.19
ml/g to 44.43 ml/g. The whole husk, average particle size, fineness modulus of husk,
dehusking efficiency of machine were varied from 55.69% to 70.57%, 300.90 μm to
353.98 μm, 2.57 to 3.08 and 73.72% to 90.68%. The variation in husk yield, number of
passes, dehusking time, dehusking capacity and power consumption were observed
from 298.21 g to 349.82 g, 17 to 66, 18.33 min to 45.17 min. 1.48 kg/h to 3.31 kg/h and
0.18 kWh to 0.66 kWh. The suitable moisture content of seeds was standardized at 9%
(w.b.). Cost of dehusking treatment and producing one kg of husk was turned out to be
₹ 64.59/kg.
The psyllium husk dehusked at standardized treatment combination were stored
in PP plastic bag (50 μ), aluminium bag (50 μ) paper bag (20 μ) for ambient storage of
180 days. The variation in moisture content of husk was 8.11% to 13.80% (w.b.), total
carbohydrate, true protein and total fat decreased from 81.47% to 76.93%, 3.27% to
2.75% and 1.80% to 1.11%. The crude fibre and total dietary fibre decreased non significantly and varied from 3.45% to 3.17% and 76.63% to 73.36%. The total ash,
acid insoluble ash, swelling volume and physiological weight was varied from 2.43%
to 2.29%, 0.56 to 0.64, 43.80 ml/g to 35.99 ml/g and 0.05 to 10.40%. Colour values L*,
a* and b* were differed from 42.21 to 41.06, 1.27 to 0.90 and 11.24 to 10.65. The colour
difference Δ E increased from 0.16 to 1.24%. Storing the psyllium husk in aluminium
bag resulted in minimum change physiochemical, functional and microbial properties
at the end of storage period and proved to be best suitable packaging material among
PP plastic, aluminium and paper bag.