Resurcb and Development Note HAND OPERA TED RICE PUFFING MACHINE-A BOON to RURAL ARTISANS in INDIA

Resurcb and Development Note HAND OPERA TED RICE PUFFING MACHINE-A BOON TO RURAL ARTISANS IN INDIA

Surya Natb and S. L. Sbrivastava*

ABSTRACT

AI it is generally seen among villagers ana village artisans that they quickly aecept improved version of their traditional technique, a mach!ne with increased output or puffed-rice bas been developed. This work is done under the Scheme of Harveat and Post Harvest Technology of ICAR at liT, K.haragpur. This machine is simple, requires no pnme mover and, haa given output almos1 fo ur times compared to traditional technique of roasting rice.

INTRODUCTION The rural population in most of the South Asian countries cannot always afford well balanced nutritious food. Malnutrition is a big problem in these countries inspite of warnings of International Agencies and the relateJ Governmental pro grammes. In India, majority of rural inhabitants are either farmers or agricul tural labourers. In the eastern part and most of the coastal regions in India, rice is the main ct op. As a result, rice· is the main staple food for most of the population. Cooked rice is mainly consumed as heavy dinner whereas puffed-rice has almost replaced other items during morning and evening snacks in eastern part of the country. The rural dwellers have developed a liking for puffed-rice not only because it is cheap but it is available in ready-to-eat form at a reasonable price. The puffed rice is locally called Murfin this part of the country.

The method of preparing puffed-rice prevalent in villages is age-old and the capacity of production is very much limited. In near future it is not antici pated that rural based production of p•Jffed-rice would be taken over by giant mar.ufactur ing establishments. The compiete process involves parboiling of paddy, drying, milling, conditioning and roasting the treated rice in sand. Unfortunately, the final

*Senior Research Officer and Senior Research Assistant respectively, Harvest and Post Harvest Technology (ICAR) Scheme, Indian Institute of Technology, Kharagpur-721302.

172 J. Agril. Engg. output is hardly 10 to 15 kilograms of Muri. Thus need of a rural based manual labour oriented machine was realised. Thereafter, Indian Institute of Technology, Kharagpur under the sponsorship of Indian Council of Agricultural Research (ICAR) launched a project in October, I 979 to study the process of making puffed-rice, roasted gram, parched rice (Khol) and pop-corn and it has been fot:nd that many o•her items can be roasted using thi~ machine. Tile increased output from a nominal amount of 10-15 kilograms to 75 kilograms of puffed-rice has enhanced the net profit of rural artisans from Rs. 10.25 (Indian) to Rs. 76.86 per day (8 hours}. In this write up deta iled process of making Muri and performance of the machine have been detailed out. It is authors' belief that 1f this mechanical device is popularised, rural artisans/traders would benefit in terms of increased output and thereby profit.

STEPS FOLLOWED IN MAKING PUFFED-RICE The parboiled rice is the only rice which is used for making puffed-rice. The co mplete process consists of parboiling, drying, milling, conditioning, preheating and finally roasting the treated rice in sand. In roasting, the rice kernel is exposed suddenly to a high temperature and the medium used is sand. Thereafter puffed r ice is separated from sand through sieve. Processes, prior to roasting the parboiled rice are done basically following the ancient method and take about 5 days. The process is done in batches and a maximum of 25 kilograms a day of puffed-rice is prepared following traditional techniques. The final output in terms of production of puffed-rice is very low. The machine developed for making puffed-rice helps in increasing the final output, though parboiled rice is prepared using the same tradi tional method. The process involved in m aking puffed-rice is shown in Figure 1. The processes are described as follows :

Parboiling It includes steeping the: rough rice in bot water and steaming for 30 minutes. It allows the vitamins and minerals present in the hulls and bran coat to be carried into the endosperm. The paddy and the water are filled in the earthen pot at 1 : 1 ratio and water is allowed to soak in the paddy for 12 hours. The soaked paddy is then boiled for about 30 minutes. The same paddy is then resoaked overnight for 12 hours and then steamed for about 30 minutes.

Drying The parboiled paddy is subjected to sun-drying andtor shed drying to reduce the moisture to 11 per cent (w. b .).

Milling In this process the husk is separated fr om the rice kernel. Milling is accom• plished by means of a foot-operated lever mechanism for giving impact to the dried

Vol. XX, No.3 & 4 173 FRESHLY HARVESTED PADDY I I .} I PARBOILING t I

DRYING I t - MILLING -I t CONDITIONING AND PRE HB<\TING I t

ROASTING I I -1- I SEPARATION t

PUPPED RICE

(ljg. 1. Flow chsrt of the puffing process for rice parboiled paddy. In rural parts it is done by traditional ways, although rice mills are operative in cities and towns specially in rice growing states. Polishing of rice is also done to a certain extent while milling the paddy.

Conditioning and Preheating Salt conditioning of parboiled rice is usually done to increase the smoothness and uniformity of puffing. A salt solution of 30 per cent concentration was sprayed at the rate of 100 millilitres per kilogram of milled rice and kept for 15 pours. The rice is now preheated under slow neat for 35 minutes in order to attain approximate grain temperature of 11 0°C.

Roasting The medium of transferring heat to preheated rice kernel i§ sand of 600

174 f. Agril. Engg. micron grade. The sand is preheated in ordinary pot (e ither earthen or metallic pot) so as to raise the sa nd-temperature to 2 50-280°C. In the mean time, the preheated rice is poured into the heated sand and stirred continuously. The ratio of sand to rice is 4 to I by weight in order to get the best performance. As there is hardly any control of temperature of sand, the quantity of fuel is increased or decreased in order to achieve the desired temperature. It takes about 12 to 20 seconds to puff up the rice.

Separation It is highly essential to separate puffed-rice from sand in order to sustain the colour and quality of the product. The longer the puffed-rice is allowed to remain in the sand bed, the more the quality deteriorates as a result of burning.

A Village Level Machine The villagerstrural artisans have been going through exhaustive and laborious work of making Muri and yet the production of puffed-rice has been very much limited. A village level machine was thought of utilizing th~ same principle of puffing the rice. Thl' machine consists of roaster's main body wh ich contains the sa nd, and rice to be puffed. An agitator is fit ted to the bottom of central shaft. This shaft is rotated by the handle, (Figure 2). The bottom of the container has opening so that the mixture of puffed rice and hot sand can be taken out by sliding the discharge gate. The machine can be fixed on some domestic furnace at a suitable heigh t to suit the spout and its operation.

In addit ion . some containers to keep sand and puffed-rice are also needed. A sieve is needed to separate sand fr om .puffed-rice. An extra attachment to cover - the top of the container is also there to protect anything dropping in or popping out. The sand in the container is heated using agricultural waste/wood and as soon as the desired temperature is attained, a specifie d quantity of raw product is fed in. The puffed product is discharged after the recommended dwelling time is over and then separated. Table I shows performance and related results in making different products.

Increased Productivity and Profitability Traditional method of making puffed-rice takes usually three labourers and yield about 25 kilograms of puffed-rice in a day. The detailed cost analysis of traditional technique and these prototypes were made with the help of artisans selected from the villages of Kashiary, Singh pur, Augarpara, Gopali and Balarampur of M idnapur district. As a case st1.1dy the process of making puffed-rice has been considered for comparison of cost and benefit using different techniques of preparing puffed-rice.

Vol. XX, No.3 & 4 175 1----1!-''-· SHAFT SAND-RIC! MIXTURE lfB!j]~~~~~~----__,,_,GI TATOR FLIGHTS

IRON FI\AME

Not to sca lt Di mensions art in em

DETAILS OF SECOND PROTOTYPE Fie. 2. Details of second protetype

Table 2 illustrates fact that using prototypes I st and 2nd, production cost of one quintal of puffed-rice, has reduced to Rs. 22 4.90 and Rs. 219.94 respectively. On the other hand respective daily net profit increased to Rs. 4·8.82 and Rs. 76.86 compared to only Rs. 10.28 under traditional technique.

It is worth to mention that this machine, t h oug~ very simple, does not need any prime mover like engine and/or electric motor and can be operated manually. It is compact, and portable and uses agricultural wastes as fuel.

176 J. Agril. Engg . Table 1. Test result• or ftoal prototype roaster Sf. No. Product num• Qty. of Puffing Tiwe /flpsed ·volume Qty. •I Remark$ raw pro· time between two expan- prepared duct, gm s~c cons•cutivtt sion product, batches rati(J kg/hr.,. ------min SIC

1. Milled ricr 500 12 2 30 7.S 10 to 12 2 kg sand at 210 °C *CMurt) temp. was used.

2. Gram 500 ~0 3 30 1.2S 7 to 8 2 kg sand at 350°C "'

3. Corn 400 1S 2 00 4.5 10 to 12 1 kg sand at 150 oc *(Popcorn) temp. was used.

4. Raw paddy 500 1S 2 30 S.2S 10 to 12 2 kg tand at 2SO °C "(Kho.i) temp. was uted . • The name refers to the prepared product respecti vely. •• fhe range is given because variety of raw product and efficiency of the operator will affect the final output,

Table 2. Comparboo of capachlea aod profits lo maklog puffed-rice

Typ~ of technique used Capacity, Cost of produc· *Ne. profit, • Net profit, kg/da' lion, Rs.iqt/. Rs.fqtl. Rs./rlay Traditional method 25 258.92 41 OS 10 28

ht Prototype 65 224 .90 75.10 48.12

2nd Pro•otype 96 219.94 80.06 76.86

• I he selling price of Muri has b~en taken as Rs. 3/·per kilogram \1980-81 price).

RECOMMENDATION In under-developing countries where rice is the main staple food, this machine has potential of adoption. A number of other products can also be roasted by this machine in addition to the ones reported in this write up. The weight of this machine being only 11 kilograms and costing about Rs. 200, it becomes much more attractive for rural entrepreneurs to go fo r custom-hiring work in the villages. Jn authors' opinion, the Government and banking agencies should provide help in popularisation and adoption of this machine through some viable credit scheme.

Vol. XX, No.3 & 4 177 ACKNOWLEDGEMENTS The authors wish to thank Dr. N.G. Bhole and Prof. S. Bal, Prof. and Head and Professor respectively, Post Harvest Technology Centre, Indian Institute of Technology, Kharagpur for their continuous help in carrying out this study. The employees of HPHT (ICAR) Scheme in general and Sri Y.K. Ojha, V.R. G ajway G.C. Majumdar and U .K. Sarkar in particular are thanked for their help rendered from time to time. Appreciations are also due to Sn N. Bagchi for typeing the whole manuscript in short time.

Special appreciations are also due to Dr. A. Alam, Asstt. Director General (Engg.), Indian Council of Agricultural Research, Govt. of India, and Dr. N . Ali, Project Co-ordinator of HPHT Scheme, for their timely suggestions, and fruitful critici1m.

178 J. Agril. Engg.