Design and development of low cost sesame dehuller and its process standardization

Abstract

The study was intended to develop a low cost sesame dehuller and optimize the dehulling process. The machine for dehulling of sesame seed was designed, developed and evaluated with different independent parameters viz. soaking time, dehuller speed and dehulling time for optimization of its performance during study. The processes variables had significant effect on response parameters whereas combined effect found non-significance. The results showed that the dehulling efficiency increases with increase in dehuller speed, soaking time and dehulling time. The optimum dehulling efficiency of 79.29% was obtained at soaking time of 120 min, 150 rpm dehuller speed and dehulling time of 6 min in this developed sesame dehuller. Mean dehulling efficiency was found to be minimum (41.84%) at 100 rpm speed with 40 min soaking time and 4 min dehulling time. The cost economic analysis discloses that developed dehuller is economically feasible and it could be beneficial for sesame based food industries. This developed dehuller is portable; therefore it requires less labor and remains suitable on farm sesame dehulling. The findings of the research may also remain useful for development of sesame processing equipment.

Introduction

Sesame, botanically known as Sesamum indicum L. is very important oilseed crop cultivated in India, China, Sudan, and Burma and bestows 60% of the world production (Abou-Gharbia et al. 1997). Beside good source of edible oil (55%), sesame seed provides a nutritious food for humans. In addition to that, it is documented as rich source of protein (20% protein) due to having unique balanced proportions of amino acids and also a tremendous source of unsaturated fatty acids and phytosterols (Yoshida and Takagi 1997).

Contrary to high nutritional content of sesame seed, the sesame seed contain 15 to 29% hull (outer fibrous cover). The presence of high amounts of oxalic acid and phytates as anti-nutrition factors in seed coat reduces the natural availability of minerals. Due to presence of indigestible fiber and unwanted oxalic acid in hull of sesame, dehulling is necessary, which confers dim color to the sesame related products (Carbonell-Barrachina et al. 2009).

Sesame hull removing may reduce oxalic acid in sesame seeds from 3.5 to 0.25%, which enhances protein digestion prominently. The softness and taste of hulled seeds are superior to the unhulled seeds (Pathak et al. 2014). Dehulling improves oil retrieval and also may improve the nutritional values and flavor of sesame products (Inyang and Ekanem 1996). Thus, sesame dehulling is the prerequisite process for expanding its application in food.

In traditionally dehulling process, sesame is soaked in a normal water or salt solution overnight. Then, sesame seeds are rubbed in a mortar or alongside a rough abrasive surface to loosen its hull. The kernels are separated from hulls using sedimentation washing (NAERLS 2010), which are dried in sun finally. However, there is an important thing related to conventional processing method as it consumes high amount of water in the dehulling based upon the physical condition of sesame seed (Gungor 2004). The old-style sesame seed dehulling method is time consuming, particularly in the soaking phase as well as laborious. The process even may produce considerable seed losses. The foremost purpose of this research was to design and development of low cost sesame dehuller, capable of separating hull from the kernel and optimizing the dehulling method for getting good quality dehull sesame seed with less water requirement.

Material and methods

Design and development of low cost sesame dehuller and its performance evaluation has been carried out at different laboratories of Department of Processing and Food Engineering (latitude 21.30052° N, longitude 70.26504° E), CAET, JAU, Junagadh. The machine (Fig. 1a–d) was designed by using SOLIDWORKS-2018 software and construction of machine was completed in departmental workshop.

Fig. 1.

Different view with its components name of developed sesame dehuller (all dimensions in mm)

Design consideration

The mechanism of existing related dehullers and shellers like flaxseed dehuller, minor millet dehusker, kodo millet dehusker and cowpea dehuller amongst others have been considered during design and manufacturing of sesame dehuller. These considerations might improve the assortment of associated features for an efficient and resourceful design of the machine. Basic manufacturing and engineering procedures were implemented to develop the huller, which perceived as a low cost, easy to operate, easy to dismantle and construct device for separating the sesame hull. Materials with tolerable strength & stability and locally available were used in manufacturing of dehuller the parts.

Dehuller mechanism

The prime function of a dehulling unit is to detach the upper hull layers of the seed with minimum damage to seed. Detachment of upper hull can be achieved by frictional and abrasion forces created by the dehulling unit in the machine. In this study, machine was designed to utilize abrasion and frictional forces generated by the turning of the screw auger circling inside a hopper simultaneously with the inter-granular frictional forces developed because of grains movement.

General description of dehuller

A dehulling unit based on the principle of smooth abrasion between grains to grain and grain to wall was conceptualized. The sesame dehuller has three basic units (1) Stand frame (2) Feeding and dehulling unit (3) Power transmission system. It involves of a fixed metal frame; feeding hopper, dehulling auger, pulley, belt, electric motor along with starter cum controller (Table 1).

Table 1.

Brief specifications of developed sesame dehuller

Parameters	Specifications
Overall dimensions	Front view: 610 × 1125 mm
	Side view: 1125 × 1630 mm
Power source	1 HP, 3-phase,, 960 RPM motor
Frame	MS angle iron (35 × 35 × 5 mm)
	(Dimensions: 920 × 610 × 870 mm)
Hopper	MS sheet 16 guage
	Length = 410 mm
	Width = 370 mm
	Depth = 255 mm
Dehulling unit	Screw auger with 5 flight rounds, 250 mm long with a screw pitch width 60 mm and screw depth 30 mm
Grain colleting tray	MS Sheet 270 mm long. 170 mm breadth and size of side wall 75 mm
Drive mechanism	Belt and pulley drive mechanism
Cost	Rs. 23,500/–
Capacity	30 kg/h
Working speed, rpm	150

Stand frame

The overall dimension of the standing frame is 920 × 610 × 870 mm (Fig. 1a, b). It consists of mild steel angle iron of 35 × 35 × 5 mm size and covered with 16 gauge galvanized steel and the entire standing frame is fabricated with the help of nuts and bolts as well as by electric welding. A feed hopper is mounted at the top of standing frame and electric motor is installed at the base of the standing frame.

Feeding and dehulling unit

The feeding hopper of developed dehuller is made from 16 gauge M.S (mild steel) sheet. It is square shaped at the top and tapered down towards its mouth (Fig. 1). The dimension of hopper is 410 × 370 mm with 255 mm depth. A slot is cut at the bottom and a piece of sheet is adjusted in order to control the outlet (Fig. 1a, b).

The dehuller design is simply a screw auger rotating inside a hopper. The screw auger is constructed from a spiral metal plate dressed and welded on a metal rod. The auger remains mounted on the frame as shown in Fig. 1c, d. Screw auger with 5 rounds of flight is extended 250 mm lengthwise, 60 mm screw pitch width and 30 mm screw depth giving 90 mm outside diameter. The shaft rotation is provided by an electrical motor using a belt and pulley system.

Power transmission system

To reduce capital investment and cost of operation, the power requirement is kept at as low as possible by utilizing the simple power train in dehulling operation. A 3-phase, 1.0 hp motor, 960 rpm electrical motor was used as power source for generating motion to shaft by belt drive. The belt drive involves of pulley and V-belt (B58). The driver pulley of 2 × 1 × B was riding on the motor and the required diameter driven (12 × 1 × B) pulley was mounted on the shaft. The whole driving system are covered with a detachable metal box for safety (Fig. 1d). The dehuller rotational speed was noted using a digital tachometer (DT-2236, India) and set as per the experimental value by using VFD (variable frequency drive) mechanism that has a rotating potentiometer switch of 2.0 hp and 420 V with frequency range 0.1–400 Hz (SJ200 series VFD, Hitachi Industrial Equipment Systems Co. Ltd). The tension of belt was tested and confirmed its rotation for the right direction.

Grain colleting tray

The sesame grains collecting tray was developed based on the frictional properties of the sesame seeds with MS sheet. The trapezium shaped of grains collecting tray is constructed by using 16-gauge M. S (mild steel) sheet with dimension of 270 × 170 mm with 75 mm depth (Fig. 1a, b). The grains collecting tray is provided at bottom of concave assembly and welded at 35° inclined to conclave axis to facilitate the grain for gentle discharge in collecting bag.

Design calculations

Feed hopper

The size of the hopper was decided by considering physical properties of sesame seed to reduce the damage during dehulling. A feed hopper of trapezoidal shape was selected (Fig. 1c, d). The dehuller was designed for approximate 25 kg/h capacity as suggested by Patil et al. (2018) and Owolarafe et al. (2013).

Design sesame seed mass occupied by the feed hopper = 5 kg

Bulk density of sesame seed = 628 kg/m³

$$\begin{array}{cc}\hfill \text{Volume}\text{occupied}\text{by}\text{sesame}\text{seed}\left(\text{V}\right)& =\frac{5}{628}\hfill \\ \hfill & =7.96\times 10^{-3}{\text{m}}^3\hfill \\ \hfill \end{array}$$

Assume maximum 1/3 volume of hopper can be filled by sesame grain

$$\begin{array}{cc}\hfill \text{Requisite}\text{volume}\text{of}\text{hopper}& =3\text{V}{\text{m}}^3\hfill \\ \hfill & =3\times 7.96\times 10^{-3}\hfill \\ \hfill & =23.88\times 10^{-3}{\text{m}}^3\hfill \\ \hfill \end{array}$$

Let a = 370 mm, b = 100 mm and L = 410 mm

$$V=\frac{\left(a,+,b\right)\times L\times d}{2}$$

$$23.88\times {10}^6=\frac{\left(370+100\right)\times 410\times d}{2}$$

$$\text{d}=248\text{mm}\text{and}$$

$$\begin{array}{cc}\hfill \theta & ={tan}^{-1}\left[\frac{\left(a-b\right)/2}{d}\right]\hfill \\ \hfill & ={tan}^{-1}\left[\frac{\left(370-100\right)/2}{248}\right]\hfill \\ \hfill \end{array}$$

$$\theta =28.{56}^{\circ }$$

where a = Top side of feed hopper, mm, b = Bottom side of feed hopper, mm, L = Length of feed hopper, mm, $\theta$ = Angle of inclination of feed hopper, v = Volume of feed hopper, mm³, d = depth of feed hopper, mm.

Size of pulley

The pulley diameter is the key point to described pulley size. It was calculated as suggested by Khurmi and Gupta (2004)

$$\frac{\text{Nm}}{\text{Ns}}=\frac{\text{Ds}}{\text{Dm}}$$

where Nm = Driver pulley speed, rpm (motor pulley), Ns = Driven pulley speed, rpm (shaft pulley), Dm = Driver pulley diameter, mm, Ds = Driven pulley diameter, mm.

$$\frac{960}{150}=\frac{\text{Ds}}{50.8}$$

$$\text{Ds}=325.12\text{mm}.$$

Belt length

The belt length of driving mechanism in developed dehuller was determined using the following expression (Khurmi and Gupta 2004):

$$L=2C+\frac{\pi }{2}\left(D,m,+,D,d\right)+\frac{{\left(D,m,-,D,d\right)}^2}{4C}$$

$$L=2\times 550+\frac{\pi }{2}\left(50.8,+,304.8\right)+\frac{{\left(304.8,-,50.8\right)}^2}{4\times 550}$$

$$\text{L}=1687.60\text{mm}.$$

where D_d and D_m are the diameter of the driven pulley and driving, respectively. L = Belt length of the pulley, mm, C = Smallest centre to centre distance, mm.

Power requirements

The sesame dehuller power requirement is determined as advised by Fakayode and Akpan (2020)

1. Total weight load of dehulling

   $$\begin{array}{cc}& =\text{Total}\text{weight}\text{of}\text{shaft}+\text{dehulling}\text{unit}+\text{pulley}+\text{sesame}\text{grains}\hfill \\ \hfill & =18.37+5=23.37\text{kg}.\hfill \\ \hfill \end{array}$$
2. Force requirements

   $$\begin{array}{cc}\hfill \text{Total}\text{force}& =W_l\times g\hfill \\ \hfill & =23.37\times 9.81\hfill \\ \hfill & =229.28\text{N}\hfill \\ \hfill \end{array}$$

   (W_l = Total of dehulling weight load, g = gravity force (9.81).

3. Torque

The shaft torque in the machine was estimated using the following expression (Fakayode and Akpan 2020):

$$\begin{array}{cc}\hfill \text{Total}\text{Torque}(t)& =\text{F}\times {\text{r}}_{\text{p}}\hfill \\ \hfill & =229.28\times 0.152\hfill \\ \hfill & =34.85\text{Nm}\hfill \\ \hfill \end{array}$$

where F = maximum force, r_p = Dehuller pulley radius, mm.

$$\begin{array}{cc}\hfill \text{Now},\text{Power}\text{requirement}\left(\text{Watts}\right)& =\frac{2\mathrm{\pi }\text{N}\text{T}}{60}\hfill \\ \hfill & =2\times 3.14\times 150\times 34.85/60\hfill \\ \hfill & =547.14\text{W}\hfill \\ \hfill & =0.73\text{hp}\hfill \\ \hfill \end{array}$$

where N = no. of rpm and T = Torque in Nm.

Diameter of shaft

Following standard ultimate strength value for cast iron was considering for calculations as

• Materiel of shaft—Cast iron

• Shear strength of cast iron rod—120 MPa (IS 210: 2009)

• Considering strength of shaft as above data.

  $$\text{Torque}\left(\text{T}\right)=\mathrm{\pi }/16\times \mathrm{\tau }\times {\text{d}}_{\text{s}}^3$$

  $$34.85\times 10^3=3.14/16\times 120\times {\text{d}}_{\text{s}}^3$$

  $${\text{d}}_{\text{s}}^3=34.85\times 10^3\times 16/(120\times 3.14).$$

  $${\text{d}}_{\text{s}}^3=1479.78.$$

  $${\text{d}}_{\text{s}}=11.39\text{mm}(\text{Actual}\text{shaft}\text{diameter}\text{is}30\text{mm})$$

where τ = shear strength in MPa, T = torque in N mm, d_s = shaft diameter.

Experimental methodology

Sample preparation

The sesame seed (variety: GT-3) were collected from the Agricultural Research Station, Junagadh Agricultural University, Amreli (Gujarat-India) were used for all decided variables and its replications. The required sesame seed were cleaned, sorted for removing undesirable materials like dust, dirt, stones and immature seeds and finally dried. The dried seeds were packed in air tight plastic bag and stored. Desired amount of material was extracted from the bag as and when required for experiments.

Water absorption characteristic (WAC) of sesame seeds

Water soaking characteristics of the sesame seeds was determined using as standard method advised by Resio et al. (2005). The randomly chosen sesame seeds soaked into distilled water beakers in 1:3 (w/v) seeds to water proportions for determining water absorption attributes of sesame seeds. Moisture content of the sesame seed at each time after soaking was calculated based on the increase in the seed weight at corresponding times. For this purpose, 15 g of seeds were rapidly extracted at regular time intervals, ranging from 5 min at the beginning to 40 min during the last stages of the process and superficially dried on a large filter paper to eliminate the surface water. At each time intervals, a fresh sample was extracted swiftly from the water soaked container and put into oven and used for water absorption determination. This procedure was repetitive until the sesame seed attained saturation moisture content i.e., when weight measurements of three consecutive varies from mean value in less than ± 1%. All results were in triplicated and these mean values were used in calculation.

$$Waterabsorptioncharacteristic(WAC)=\frac{Ws-Wi}{\mathit{Wi}}$$

where Wi = initial mass, (g), Ws = saturation mass, (g).

Performance evaluation and optimization

The optimization of three independent parameters (seed soaking time, dehuller speed and dehulling time) that mainly affect the performance of a dehuller were selected so as to maximize dehulling efficiency with minimum seed damage. The water soaking of sesame seeds as pre-treatments were selected in term of soaking time, based on the availability and manageability of those moisture levels at farmers' field. The pretreated sesame seeds then fed to the developed dehuller at various dehuller speeds and dehulling time to know the effect of machine parameters. The levels of dehuller speed and dehulling time were taken based on preliminary trial as well as research reviewed during study as follows (Said and Jadhav 2021).

1. Sesame soaking time (M): 40, 80, 120, 180 min

2. Dehuller speed (S): 100, 150 and 200 rpm

3. Dehulling time (T): 4, 5, 6, 7 min.

Dehulling efficiency (η_de)

The dehulling efficiency was estimated for accessing the performance of developed dehuller. The dehulling efficiency was estimated using 5 g (~ 1800 seeds) of randomly collected sample seeds for each run. The extracted samples were placed on petri dishes, spread in small groups and counted by using colony counter. For the ease of visualization, colony counter with magnifying glass and lamp were used while counting the sesame seeds. The sesame seeds were calculated in regard of unhulled, dehulled and damaged seeds. Damage seeds means, dehulled but fractured, changed in form, oppressed, flat etc. (Gungor 2004).

$${\eta }_{\text{de}}(\%)=\frac{Wi-\left(W,u,+,W,h,+,W,b,m\right)}{\mathit{Wi}}\times 100$$

(where Wi = Initial sample weight, Wu = Weight of unhulled sesame, Wh = Weight of hull and Wbm = weight of broken and meal).

Statistical analysis

The data were analyzed and standardized using the MS-Excel 2010 and ANOVA done by factorial completely randomized design (F-CRD) to describe the dependence of dehulling efficiency on variables studied (Panse and Sukhatme 1954). Forty eight treatment combinations with three replications were evaluated in this study and the mean values were reported. Each test was replicated thrice, and the mean values reported. Means and analysis of variance (ANOVA) were conducted (p ≤ 0.05).

Results and discussion

Physical properties of sesame seeds

The sesame seed physical properties were determined so as to make use of these values while designing various components of sesame dehuller. The procedures suggested by Mohsenin (1980) were followed for physical properties determination. The maximum, minimum and average values with its standard deviation of the sesame seeds physical properties was measured and noted in Table 2. The 1000 seed weight range from 2.28 to 3.70 g, roundness varies 0.27–0.44 whereas length of the sesame seeds ranged from 2.45 to 3.69 mm, width from 1.35–2.21 and thickness 0.67–1.05. The sphericity of sesame seeds ranged from 1.39 to 1.93 while geometric mean diameter various from 0.20 to 0.12 mm. The sesame seeds had a bulk density, true density and porosity of 653–1241 kg/m³, 1148–1379 kg/m³ and 41.12–54.59%. The mean value of sesame seed surface area, coefficient of friction (GI surface) and angle of repose were determined equal to 8.65 mm², 0.34, 37.48° respectively. The determined physical properties of sesame seed were in overall agreement with the results reported by Khazaei and Mohammadi (2009); Tunde-Akintunde and Akintunde (2004) except sphericity is quite less as data reported by others.

Table 2.

Physical property of sesame seeds (at 6.70% moisture content, w.b.)

Parameter	Avg. value	Max	Min	SD
1000 seeds weight, g	2.96	3.70	2.28	0.03
Roundness	0.35	0.43	0.27	0.08
Length, mm	3.10	3.72	2.33	0.24
Width, mm	1.77	2.23	1.36	0.22
Thickness, mm	0.82	1.03	0.63	0.15
Geometric mean diameter, mm	1.65	2.13	1.30	0.21
Sphericity	0.15	0.19	0.13	0.02
Aspect ratio, %	57.14	69.14	46.85	3.20
Seed surface area, mm2	8.65	11.25	7.35	2.18
Bulk density, kg/m3	628	653	596	6.01
True density, kg/m3	1233	1379	1148	24.66
Volume, mm3	3.58	4.26	3.01	1.26
Porosity, %	48.90	54.59	41.12	3.20
Coefficient of friction (GI materials)	0.34	0.40	0.28	0.01
Angle of Repose, °	37.48	48.35	28.86	1.10
Terminal velocity, m/s	4.86	5.83	3.79	0.06

Kinetics of water absorption

Dehulling of sesame seeds needs, the sesame seeds are soaked in water for loosening of hulls (Hussain et al. 2016). Therefore, practical understanding about water absorption phenomena of seeds is very important. The theory of water uptake during hydration of sesame seeds are shown in Fig. 2. This figure shows that the sesame seed displayed higher increase in water uptake in the starting followed by lower absorption in final stage, i.e., relaxation phase. Khazaei and Mohammadi (2009) also reported similar graphical pattern for water soaking of sesame seed at various temperature. These results are also agreed with earlier studies which have described indistinguishable curves during other grains or seeds hydration (Sopade and Obekpa, 1990; Bello et al. 2004). Approximately after 80 min of soaking, occurrence of a transition between primary and secondary phases are observed (Fig. 2). The average value of absorbed moisture during the subordinate stage was about 1/3 of the whole absorbed moiture. These results in line with the earlier published studies (Sopade and Obekpa 1990; Turhan et al. 2002; Shafaei et al. 2021).

Fig. 2.

Water absorption characteristics of sesame seeds

Effect of variables on dehulling efficiency of developed sesame dehuller

After development of the sesame dehuller, its performance was assessed and standardized and these results were demonstrated in Table 3 and illustrated by Fig. 3a–c. The optimization of dehulling process parameters such as sesame soaking time, dehuller speed and dehulling time is necessary to obtain maximum dehulling efficiency. Generally, the dehulling efficiency increases with increase in dehuller speed, various sesame soaking time and dehulling time up to certain levels. The maximum mean dehulling efficiency (79.29%) reported by machine was at 150 rpm dehuller speed with 120 min sesame soaking time and 6 min dehulling time (T31) and minimum (41.84%) at 100 rpm speed with 40 min soaking time and 4 min dehulling time (T1).

Table 3.

Observed dehulling efficiency and hull yield under varying processing parameters

Treatment	Treatment detail		Parameters
	Soaking time, M (min)	Dehuller speed, S (rpm)	Dehulling time, T (min)	Dehulling efficiency (%)
M1S1T1	40	100	4	41.84
M1S1T2	40	100	5	47.05
M1S1T3	40	100	6	53.25
M1S1T4	40	100	7	56.00
M1S2T1	40	150	4	47.25
M1S2T2	40	150	5	52.83
M1S2T3	40	150	6	57.41
M1S2T4	40	150	7	62.01
M1S3T1	40	200	4	50.56
M1S3T2	40	200	5	56.40
M1S3T3	40	200	6	61.21
M1S3T4	40	200	7	66.05
M2S1T1	80	100	4	46.32
M2S1T2	80	100	5	51.88
M2S1T3	80	100	6	58.51
M2S1T4	80	100	7	61.45
M2S2T1	80	150	4	52.09
M2S2T2	80	150	5	58.03
M2S2T3	80	150	6	62.96
M2S2T4	80	150	7	67.87
M2S3T1	80	200	4	55.65
M2S3T2	80	200	5	61.84
M2S3T3	80	200	6	67.01
M2S3T4	80	200	7	72.19
M3S1T1	120	100	4	52.79
M3S1T2	120	100	5	58.75
M3S1T3	120	100	6	65.89
M3S1T4	120	100	7	69.04
M3S2T1	120	150	4	66.83
M3S2T2	120	150	5	73.56
M3S2T3	120	150	6	79.29
M3S2T4	120	150	7	77.52
M3S3T1	120	200	4	61.57
M3S3T2	120	200	5	68.07
M3S3T3	120	200	6	75.89
M3S3T4	120	200	7	69.12
M4S1T1	180	100	4	48.87
M4S1T2	180	100	5	54.60
M4S1T2	180	100	6	61.37
M4S1T4	180	100	7	64.39
M4S2T1	180	150	4	58.44
M4S2T2	180	150	5	64.80
M4S2T3	180	150	6	70.12
M4S2T4	180	150	7	74.07
M4S3T1	180	200	4	54.80
M4S3T2	180	200	5	60.89
M4S3T3	180	200	6	65.93
M4S3T4	180	200	7	70.97

Factor	S. Em ±	F-test	C. V (%)
M	0.61	S	6.03
S	0.53	S
T	0.61	S
M × S	1.06	S
M × T	1.23	NS
S × T	1.06	NS
M × S × T	2.13	NS

Values are indicated in bold letter to suggest optimum combination for getting maximum dehulling efficiency in developed sesame dehuller

Fig. 3.

Effect of a dehuller speed, b dehuller time and c soaking time on dehulling efficiency

The increase in soaking time let to rise in dehulling efficiency (η_de) up to 120 min soaking time (68.19%); thereafter it was decline at 180 min soaking time (54.32%). This is due to more loosening of the outer hull of sesame seed at higher soaking time (Fig. 3c). In addition to that, the high seed surface moisture content may reduce the seed to seed friction and thus it declines the dehulling efficiency as well as deterioration of sesame seed quality during the seed soaking. These findings have also bond with Kaur et al. (2014) for 40 min to 120 min soaking time but do not conform with their finding from the 120 min to the 180 min of water soaking. This results also in line with results reported by Gungor (2004). The Said et al. (2011) also reported similar results in nutmeg decorticator, context to the initial moisture content.

The dehulling efficiency was significantly (p < 0.05) vary with increase in dehuller speed. In Fig. 3a, increase in the dehuller speed commanded to enhance the dehulling efficiency up to 150 rpm dehuller speed. Gelgelo (2014) also observed increase in groundnut shelling efficiency with the increase in dehuller speed and moisture content. Nevertheless, furthermore increase beyond 150 rpm directed to a reduction in dehulling efficiency. This might be due to increase in the dehuller speed developed enough electrical power which was extremely high, accordingly leading to enhancement in damaged and broken sesame seeds. The Mahawar et al. (2020) and Said and Jadhav (2021) were also noted that the decortication efficiency was influenced by dehuller speed. Said and Jadhav (2021) was also observed the initial moisture content and dehuller speed had significant relation with dehulling efficiency. The dehulling efficiency data of interaction between sesame soaking time and dehuller speed shows the significant difference at 5% level of significance.

It was noticed that at the similar sesame soaking time and dehuller speed levels, increase in dehulling time steered the increase in efficiency of hulling. This is evident due to the fact that at more dehulling interval, sesame seed got optimum time to dehull. After the 6 min. dehulling time interval dehulling efficiency start to decrease. Results also show that the dehulling time significantly affects the mean data of dehulling efficiency of sesame with at 5% difference level of significance (Table 3). These outcomes are also accordance to results conveyed by Oomah et al. (1996) for flaxseed dehulling.

The breakage were recorded quite low, a mere < 1% while unhulled grains obtained in range of 2–12% during the study. The almost inline findings were also stated by the Pradhan and Pradhan (2020) for Chironji (Buchanania lanzan) nut decorticator. As per their research, non-significant increase in broken percentage was observed with increase in dehuller speed. Although the less breaking is admirable, high damage may be predicted at higher soaking time and operation speeds. The combined effect of dehuller speed, sesame soaking time and dehulling time on dehulling efficiency was analyzed using Factorial Completely Randomized Design (FCRD) and result of the analysis are shown in the Table 3. There were non-significant difference in interaction effect of parameters were noted except the interaction between sesame soaking time and dehuller speed shows the significant difference at 5% level of significance.

Economic analysis of the developed dehuller

Cost economics of developed sesame dehuller was calculated as per method suggested by Jethva and Varshney (2016). For the successful commercialization of any fresh machinery, it is crucial to identify whether the machine is economically feasible or not. The operation cost of the developed dehuller was calculated by considering the full utilization of the machine for custom hire basis for entire season (1600 h/year). The cost of construction of machine was Rs. 23,527. Including initial cost of machine as capital investment, the fixed cost per hour for the operation of the machine is the sum of depreciations and housing and taxes become Rs. 2.28, while the total variable cost including repair and maintenance, labor charges, electricity, etc. was Rs. 49.70. The dehulling cost of developed dehuller per kilogram came to about Rs. 2.08. The cost and payback analysis comprises BCR, NPW as well as PBP, which indicates the optimal realization of all the financial constraints in using the developed machine for sesame dehulling. A benefit cost ration higher than 1 indicates that the machine is hypothetically advantageous. In develop sesame dehuller BCR was obtained 1.95, designating that the machine is very advantageous and cost-effective. Therefore, this dehuller is more appropriate for small as well as medium scale sesame processor. Payback period is the time span need to recover the investment (Pascua 2018). A low pay back period of 11 months and high NPW of Rs.150968 were assessed for sesame dehuller showing its acceptability for commercial sesame dehulling. Thus, economic analysis conducted for dehuller concluded that the developed dehuller is economically worthwhile and appropriate for small as well medium scale sesame processing industries.

Conclusion

The traditional sesame dehulling method is laborious, time intense and need much more volume of water in dehulling process. To overcome this problem, work on design and development of low cost sesame dehuller machine which is capable of separating hull from the kernel was undertaken. The dehuller was assessed at various speeds, dehulling time and moisture soaking time, which affected significantly the dehulling efficiency of the dehuller. The performance of the developed sesame dehuller was noted acceptable in regard of the dehulling efficiency. For getting maximum dehulling efficiency in this developed machine, the sesame seeds are required to be soaked in water for 120 min and then dehulling has to be carried out for 6 min. The machine has a capacity to dehull the 25 kg of sesame seeds with dehulling efficiency of 79.29% at 150 rpm dehuller speed. It has been developed from low cost materials available locally and is made portable to suit the on farm dehulling. A dehuller of this nature can be useful for small as well medium scale sesame producers, processers and sesame processing industries. The develop dehuller will confidently benefit farmers by giving the worth to agricultural produce. The cost of the sesame dehulling by developed dehuller is Rs. 2.08/kg.

Author contributions

DKG: Conceptualization; formal review analysis; Design and development; Fabrication; performance evaluation; writing original draft; writing-review. VNG: Conceptualization; investigation; writing-original draft and editing.

Funding

The authors acknowledge the financial assistance for supporting the investigation received from All India Coordinated Research Project on Sesame, Indian Council of Agricultural Research, New Delhi and Junagadh Agricultural University, Junagadh for supporting the investigation.

Availability of data and materials

Not applicable.

Code availability

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Declarations

Conflict of interest

The authors have no conflict of interest to declare.

Consent to participate

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Consent for publication

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