STUDIES ON METfiODS OF PA~HOILJ ~G

. ·~. •, ,~' "< ·- -PRESSURE PA ~BOILIN G. , ''

i N.G;C. lENGAR, R: BHASKAR, P. DHARMARA JAN,*,•

ABSTRACT .. ··;·,

,f~ . " ' 't~ A meth od of quick parboiling pf paddy has .been worked out using high pre- · ., ,ssure steam wh ich reduces the soaktng and parboiling to 1.5 hrs per batch. The process is cheap in comparison with the methods of parboilmg being carried out _;;. in this country. The method is very suita]Jle for small units located in rural areas, .. -'particularly when combined wi th boilers fired by paddy hu3k, for producing steam and power for parboiling·and drying. ·By this method, breakage of the kernels is ,,, reduced considerably. The mill eut·turn capacity of this method of parboiling is very high and ·a product with a high consumer appeal can be turned out. ·

Introduction ' ~ .,. ' ·....

At present a large prorortion of rice consumed in India is p1rboiled. Various methods of parboiling are used. In the household method the washed paddy is placed in an open vessel and covered with cold water to a level of 50 mm above the surface of the paddy and heated gently to simmering temperatures just below boiling point of water. This " temperature is maintained overnight. After this, the water is drained off and paddy is steamed until steam emerges at the top. Steaming is done for 5 minutes. The steamed paddy is dried under sun. The product is uniformally soaked and- well parboiled without any off odour, and has an attractive colour. In the commercially adopted, "traditional method", as followed in South !nd!a,_open_air soaking tanks pf larga capacity are used. Cold water soaking upt62ili~.~ is f~fo~ed ' with or without d~il y change of soak w:ater. At the end of the soaking period water is drained off and the wet soaked paddy steamed in open steaming ke ttle for 15 minutes using low pre~su.r_e _steam. ..~,u, , drying in open, is followed h; l~ t~~~J ll].~t ho:d! thQ_Mg~ - g~od SOaKi?k' iS achie~ee an~ > a l!ght COJ_our~~ -!ice is got, therets m~arJabl y ~., ~ont~m!~tf8p by soil at);~tf~~cal _ bac_fiBha, whi_ch ~re mtro~~?ed by uncleaned paddy, lllnTrea~d w~ter ana by du~t ; c?~ta .~~,pr;~,tJOn IU Qpen ,ttl~' Jtiuks: · 'Jlne ~' result is an active fermen\'!lg{'6I1ff)V.hiah f.e'S'tffts in the 'production of protein breakdown products which are absorbed by the paddy and impart a foul odour to it. During open drying the burst kernel acquires fu ngal infection. During drying, tne paddy is freely attacked by crows and sparrows. To reduce the soaking time, double steaming is done, the initial steaming being done on the raw dry paddy for 15 minutes. This to a certain extent sterilizes the paddy and the microbial load is reduced. This position is further improved by daily change of water. The result is an improved product. Soaking time is reduced to 48 hqurs *Resea1ch and Development Laboratory, Tanjore Gooperative Marketing Federation Ltd., Tiruvarur (Tamil Nadu).

40 J. Agril. Engg, '.. ' I ' by this procedure. In order to improve the hygiene of the method of parboiling to reduce the soaking tr me and to eliminate the smell, the method evolved by CFTRI Mysore, using hot soaking for 3.5 - 4 hours at 70 - 75°C was recently introduced Steaming is done in open kettles and drying is done on open plinths. Introduction of mechanical dryers was the next im provement in the parboiling procedure The latest improvement has been a chemical method for preventing the opening of the soaked paddy and for reduc­ ing the drying time of parboiled paddy. This method evolved by Dr. V. Subrahmanyan and Mr. B.S. Vasan at TCMF Lab uses brine containg 15% Sodium Chloride as an osmotic agent. When the hot soaked paddy is treated with brine of this concentration, the salt which is retained at the bran layer, exerts an osmotic action which helps in the quick removal of water from the kernel of the soaked paddy. The salt does not permit any water to move in the reverse direction. If such paddy is then steamed, parboiling occurs at 23 - 24% level of moisture on the kernel. At the end of the parboiling operation the kernel has a lower moisture level than the hw.k and the sodium ion acts as a pump which facilitates transfer of moisture from the kernel to the husk. Thus drying effort, the drying time and cost are greatly reduced. The drying time, using LSU driers is reduced from 4- 5 hrs to 1.5 hrs. Any method of mechanical or chemical chemical drying under humid condi­ tions is an asset in South India where during the N. E. Monsoon. the sky . is overcast for weeks and drying of parboiled paddy is impossible. At present the result is that parboiling operations have to stop du.ring this period.

However the present methods of parboiling whether in H uller, sheller cum polisher, or rpodern rice miHs suffer from the fact the methods are ong and complicated. The authors felt that if the soaking period is reduced or even elimina .ed and the process made more simple and hygienic and if the soaking and parboilmg are combined in a single operation, it would be a great advantage. With this object in view, the present work was taken up.

Methods and Mate ials

After a series of laboratory trials covering a number of pad Jy vanettes the authors an ived at the following procedure as a first measure : (a) waslmg and cleaning of paddy to remove the chaft and immature grains which cause discolouration in final material and reduce the yield (b) raising the temperature of soaked water to 95°C and maintaining it at that ternpature for 20 minutes. This avoided the white bel y formation considerably. Soaking was s~tisfacto ry. (c) Draining off the water and letting i'l the open steam and rarsing the pressure of the vessel to 10 psi (d) maintaining at 10 psi fo r 20 minutes (e) At the end of this period the paddy was unloaded and dried. The resultant product was a tough grain with a light yellowish colour which could be easily shelled even at 17% moisture content and the breakage during milling was negligible (0.5 to 2%) If dried immediately after unloading from the parboiling plant, the•entrapped heat (which was considerable) permitted quick drying. Even shade drying under a fan was rapid. The drying time on LSU driers was at least 1.5 hrs Jess than on the paddy parboiled by CFTRI 'llethod.

2) As a seco r.d sta~e. an attempt was made to avoid soaking altogether. (a) The

Vol. IX, Nu. 4 41 paddy W

3) As the possibility of the pressure over a period causing browning was pointed out an attempt was mad

4) Though a very latge number of paddy vanettes were tried out successfully, the major part of the large scale trial work was done on varieties common to Tanjore District namely Co-25, ADT-27 IR-8, ASD-11 & ADT-8. For these varieties the ideal treatment recommended is 20 minutes soaking at 100°C draining off water and 10 minutes of auto­ claving at 15 psi.

Large Seide Trials

Large industrial scale trials to test the efficacy of the method were carried out by using batch extractor installed at the Bran Oil Solvent Extraction pic nt located at T.C.M.F. Two lots of ten tonnes each were processed in 15 tonne batch extractors and a large number of trials were carried out in 1.5 tonne baby extractors of experimental type. Nearly 370 tonnes of paddy were parboiled by this method. Soaking was uniform and the strength of the grain was very good, with the result that the shelling and milling efficiency were quite high. The product was of a high second class quality with a high consumer acceptability. One of the significant finding was the uniform, high extractable oil content of bran. The rice had a glistenfng appearance with a uniform light colour. The grains were greasy with oil. This adhering oil could be easily extracted by using deoiled fine bran and giving. a polish without any loading. The! oil content of this deoiled fine bran can be built up by stages. The authors suceeded in enriching the dtoiled bran to 23-25% of oil. This bran can be re-extracted and oil recovered.

In the earlier experiments dry paddy was fed in and wetted with cold water. This effected some washing also. The Wdter was then drained off. Live steam was introduced and pressure built up to 12 psi and maintained at I 0-12 Psi for 25 minutes. At the end of this period, the steam was cut off, the paddy emptied and straight away spread on a

J. Agril. Engg. drying plinth. The product obtained was satisfactory except for a degree of browning due to preheating of the paddy before procurement and for some red grains due to immature paddy. The mill ing yield was high (73.6%). The brain obtained was of high quality and yielded over 27% of oil with low F.F.A. content. 1here was some adverse criticism about the presence of white bellies up to 5%. So it was decided that some soaking should be given. Paddy was soaked in cold water for one hour. Th is cold soaking permitted the removal of chaff and inmature grains and this improved the quality considerably. This chaff removal was carried out by a perforated ladle. After the cold soaking the water was drained off and the paddy was autoclaved at I 0 p.s.i. fo r 35 minutes with open steam.

With cold soaking, the time required for each batch was about 2 hours in the above experiments. To reduce this time, it was decided to adapt hot soaking. Water at IOO ' C was introduced into the tank and paddy fed in. The temperature of water dropped down to about 65°C. Jacket steam was introduced and the temperature was raised to 95°-l00°C for 30 minntes. The water was then drained off. During this treatment chaff was removed by skimming as usual. At the end of the period, the jacket steam was shut off and open steam was introduced. It took usually 15 minutes to raise the temperature in the extractor to 1 15-120oC (ie. approximately I 0 - 12 p.s.i. ). The paddy was treated under pressure for 18 minutes. At the end of this period the extractcr was discharged and the paddy spread out for open drying. The product was quite satisfactory and very uniform in quality. With small grain varieties however there was an incidence, to a small extent, of pin point white bellies. The colour was a light yellowish white and the grain was hard and tough. Table-I provides some typical milling reports ·on these batch experiments.

Table 1. Milling Results of Pressure Parboiled Paddy.

Test Ti me Paddy Head Brokens Bran Polish Date in Hours Kg. Rice Kg. Kg. Percentage Kg. ---· -- - -- 23.3.70 12.00 10,750 7,907.5 560 5.9 4.4.70 10.00 5,700 3,727 101 197 do do do 5,900 4,523 75 160 do do do 4,:,oo 3,207 160 do 20.4.70 6.3 0 14,300 10,780 73 670 do 7.5.70 8.00 8,750 6,714 421 440 do 9.5.70 13. 15 22,000 16,337 150 1,240 do

Total 49.15 71,900 53,196 790 3,427

The paddy milled was of co-25 variety. The percentage of head rice recovery was 73.71 and that of brokens was 1.09.

Vol. IX. No. 4 43 By the above method the entire time of parboiling including soaking was n:duced to about one hour. On the plant scale the authors have carried out three batches per shift, so that on the 1.5 tonnes unit 4.5 tonnes could be parboiled n one shtft and 13 .5 tonnes per day. With two baby extractors operating simultaneously 27.0 tonnes can be handled easily per day. In the laboratory, using the above method as many as eleven batches have been handled, in a shift of eight hours allowing for two '1ours for lunch and tea breaks.

Using a larger sized batch extractor of 15 tonnes capacity, trials were carried out to see whether the above method would work on a large scale plant. Two batches each of 12 tonnes were treated. Cold soaking was carried out for one hour fo llowed by autocla­ ving for 35 minutes at 10 - 12 p s.i. The experiment was successful. The product obtai­ ned was satisfactory. In the big extractors however, two handicaps were experienced. The removal of chaff was not satisfactory and the rise in temperature was rather slow . The paddy in lower portions of the batch being treated tended to get burst as the steam injection pipes were located at that level. There was also a condensation of steam on contact with cold paddy and a degree of cooking occurred in the earlie r batches but when jacket steam was used the heating was quicker and cooking of paddy was avoided. Th1s indicates that the arrangement of steam injection pipes should be carefully done to assure uniform distribution of steam at all levels and to achieve the requisite rise in temperature in minimum time. Removal of chaff was rather difficult and not satisfactory in large extractors. This indicates that precleaning devices should be thoro 1gh and that only cleaned paddy should be fed for parboiling by this method.

Majority of the pressure parboiled batches were open dried due to inaccessibility to the driers. In order-to test the behaviour of the pressure parboiled paddy under conditions of mechanical drying a few large batches were dried in the L S. U. drier of the oil fired type and the S. E. drier of the steam heated type. In all these eases the parboiled paddy had to be transported by tractors to the drying unit which was about a furlong away. During manual, loading and unloading and transport considerable cooling of the paddy had occurred wh ich increased the drying time. Even so the drying was quite fast as no adherent moisture was there. It was generally found that n the L·S.U. Drier there was a general browning of the kernel, the effect of which was absent in the steam heated driers. The dryin f?; time was about five hours to bring down moisture content from about 30% to I 5%.

On a laboratory scale the parboiling, was tried by using a higher temperature and pressure. With 20 mins. of soaking at 100°C and I 0 minutes of autoclaving at 15 p.s.i , good parboiling without white bellies was achieved and a rice of light colour and good toughness was obla.ned on five varieties of rice including Co-25, ADT-27, lR-1 I and ADT-8. With this expenment the entire soaking and parboiling operations could be completed in 30 minutes per batch. In each of these varieties, treatment at 15 psi for 5 minutes ~as also tried out. There was a slight improvement in colour; but for uniformity of product and ease of operation, 10 minutes at I 5 p.s.i. are recommended.

41 J. Agril. EngK. So far, over 370 tonnes of paddy of paddy have been parboiled by tjl.is method and the consumer acceptability of the rice has been uniformally good. Cost data is given in the appendix.

Equipment for Permanent Set up for Perssure Parboilin2 - General Hints

i) The most convenient size is a 3 tonne unit. With this type of equipment it is possible to parboil in one shift fi ve batches each taking one hour. This allows 3 hours per shlft for lunch and tea breaks and unforeseen contingencies. With this level of working it is possible to produce 45 tonoes per day. (if 15 tonnes through-flow capacity in provi­ ded for the drier, it is possible to dry the paddy conveniently).

ii) The parboiling tank should be raised just 1.5 m above the ground level to pro­ vide for a belt conveyer which will take the parboiled material either to the drying yard or to the dryer. Belt conveyers made of proper material would be much more economical and more convenient to handle and maintain than scr.!W conveyers. The conveyer can be housed in a wooden trough which can be easily be opened for taking out the spillage.

iii) The parboiling tank can be fed directly from an over head bin through a canvas hose attached to a valve. The feeding may be done through the hose which can be easily lifted off once the feeding is completed. The over head bin can be fed with precleaned paddy either by an elevated belt conveyer or through bucket elevator. Precleaning to remove all sand and clay and chaff is absolutely essential.

iv) The feeding man hole can be in the centre of the parboiling tank, and should be hinged to allow of easy lifting. Sui~able gasket is necessary. It is better to provide a wide enough drain hole with a hinged door fitted with nuts and bolts on the side near the top so that easy removal of chaff can be done. The chaff can flow off with the excess water for soaking into an open side-chute. After the chaff removal is complete, the drain hole can be closed by the gasket fitted hinged door which can be easily secured with winged nuts and bolts.

v) Proper and quick drainage facility should be pro vided at the bottom of the parboiling tank wh ich may have an inverted dome type of bottom. At this place, drain cocks of adequate size, may be provided. The hot drainage water can be delivered to a ground level insulated tank, from which, it may be pumped for re-use in the next batch or the water can be used for pre-heating boiler feed water.

vi) The parboiled paddy should be unloaded from the side at the bottom of the parboiling tank through an inclined chute which will deliver the paddy to the belt conveyer. The delivery manhole should be proyided with a hinged door which is gasket fitted and can be tightly fastened with nuts and bolts so that proper pressure can be maintained.

vii) The soaked paddy can be placed on a perforated sheet of sufficient thickness (atleast 3 mm thick) with six holes per 6.45 sq em. The holes should be of a size small enough to retain paddy grains. The delivery door can be located on the side immediately

Vol. IX, No . 4 45 above this plate. This plate may be located at 0.45m. above inverted dome bottom.

viii) Proper jacket steam device should be provided for ensuring quick attainment of temperature by water used for soaking and its maintenance at a proper level. This steam jacket should have its own temperature and pressure indication devices.

ix) For ensuring proper parboiling without excessive bursting of the paddy grain and to prevent excessive heating of a particular section of the tank, which can lead to discolou­ ration, uniform heating of all sections of the tank is necessary. This can be achieved by placing the paddy inside a perforated cyl inder which can be continuous with the perforated bottom plate. The steam inlet pipes can be outside this perforated cylinder. In order to ensure quick rise of temperature throughout the paddy mass and to ensure uniformity of that temperature, the steam entry should be atleast at four inlet points each set at 90° angle. The steam entry pipes can be either as rings or the steam entry can be made into a chamber which runs right round the perforated basket with control valves to ensure that the entry is simultaneous all rou.nd and at the bottom. It may be advisable (but not quite necessary) to have a pe rforated steam inlet pipe at the centre also to ensure quick heating up there.

0 PAOO't !!.IN 1,2,3,<4 ,5 ARE STEM INLtT VALVES SLAT VALVE.

HINGED MANHOLE. CCV(R 8 WITH NUT AND 80LT u c DOOR K. E T PERFORATED METAL BASkET AND PARBOUNG PADDY

DISCHARGE. HI NGE DOOP Y,_.__ WITH GASKET , I~UT AND BOLTS F'OR F'AST£N ING

OPEN CH UT C. TO BE.Ll' CONVZYOR,

BELT CONVEYOR TO DRYE.R 0

Fig. 1. Pressure Parboiling Plant -46 J. Agril. Engg. x) The parboiling chamber should be fitted with a dial thermometer and a pressure gage so that proper temperature and pressure control may be maintained.

xi) Water entry pipe should be located at the top of the parboiling tank. It is better to fill water up to half the required level and then feed the paddy and the water together in a regulated way so that the chaff flo1ts up quickly any can be effectively removed.

xii) The parboiling tank can be supported on a metal ring of sufficient thickness standing on four metal stanchions properly fixed in concrete bases. It is better to protect the inner and outer surface of the tank with heat resistant Epoxipaints of the proper type to prevent rusting. A diagram of a unit built according to the above scheme is provided in Figure I.

ACKNOWLEDGEMENT

The authors herewith express their gratitude to the Authorities of Tanjore Coopera­ tive Marketing Federation, Tiruvarur and particularly to Mr. V.S. Tyagaraja Mudaliar. President, T.C.M.F. for permitting the authors to carry out this work in their laboratory and for the permission to use the 15 tonnes and I. 5 tonnes extractors for large scale trials. They seek this opportunity to express their gratitude to Prof. V. Subrahmanyan, Emeritus Scientist and Hony. Adviser, Min. of Food, Govt of India for encouragement and gui­ dance at all stages of this work, and M/s. K V. Rao, Chtef Chemist, Solvent Extraction Plant and Mr. Nagasubramanyan, Chief Engineer (Prod), T.C.M.F., Tiruvarur for their cooperatio_n and guidance in the large scale experiments and calculation of costing data.

APPENDIX-A

Approximate Operating Cost Using the 1.5 Plant (Per Batch of 1.5 Ton) i) Parboiling

1. Labour charges for loading at 90 paise per tone. .- Rs. 1.35 p 2. Water charges for 3000 litres (including pump charges Rs. 0.10 p 3. Steam required per batch 100 kg (using oil fired Lancashire Boiler) .- Rs. 7.00 4. Unloading charge at Rs. 1.5 .per tonne. Rs. 2.25 5. Helper at Rs. 5 per diem (3 batches per shift) Rs. 1.66

Total parboiling cost per batch of 1.5 Tonnes Rs. 12.36 : . Cost per tonne Rs, 8.24

Vol. IX, No. 4 47 If husk fired Schule boiler is used the cost of parboiling will come to Rs. 4.50 per tonne. ii) Drying

The drying of one batch of 5.5 tonnes takes 6 hours using 30 litres of furnace oil per hour costing Paisa 31 per litre

. . Cost of fuel comes to Rs. 55.80 for 5.5 tonnes. . . The cost of drying works out to Rs. 10.10 iii) Total Cost of Parboiling and Drying

a) Using Lancashire boiler steam Rs. 18.34 b) Using Husk fi red boiler Rs . 14.60

APPENDIX- B

cost of plant a) Approximate Cost of Installation

1) Cost of 3 Tonnes capacity parboiler Rs. 7,000(- ' - 2) · Cost of overhead bin (6 tonne capacity) - Rs. 1,5001- 3) Bucket elevator (15 ft high) at Rs. 250/- per foot, including cost of Motor Rs. I 000/- - Rs. 4,000/·

Cost of Mechanical equipment Rs. 12,500/- b) Civil Works

Shed for Accommodation Rs. 4,500/­ Stanchion for Erecting the parboiling tank Rs. 2,000/­ Installation charges :- Rs. 3,300/-

Cost of Civil works Ks. 9,800/- c) Schu)e Boiler

I) Schule Boiler Rs. 10.000/­ 2) Mechanical requiremen\ Rs. 12,500/­ 3) Civil woJks Rs. 9,800/-

Total cost involved in installation approximately Rs. 32,300/-

48 APPENDIX- C

COMPARATIVF DATA:- Using oil fired Lancashire boiler for steam products and L.S.U. Type of oil fired drier for drying pupose the costs per tonne are

a) Bn ne parboiling :- Rs. 35.65 b) C F.T.R.I. Method .- Rs. 38.80 c) Pressure Parboiling Rs. 24.50

APPENDIX-D

Approximate Data for Pressure Parboiling

15 Tonnes Plant a) Parboiling Process

i) Loading labour charges at 90 P. per tonne using bucket elevator & screw conveyer Rs. 13.50 ii) Power cost for conveyer mentioned above Rs. 2.00 iii) Water requirement 12,000 litres cost (including pumping charge) Rs. 00.50 iv) Steam required per batch (using oil fired Lands­ hire boiler) at Rs. 7/- per 100 kg. Steam requir· ment 600 kg per batch Rs. 42.00 v) Unloading at Rs. 1/50 per tonne (unloading is manua and the labourers demand extra for unloadmg hot paddy) Rs. 22.00 vi) Hf.lper Rs. 5/- per diem. At least thne batches can be done per day. Helper charge per batch will therefore be actual Rs. 1/66 Rs. 5.00 viii Parboili ng cost for 15 tonnes is Rs. 85/50 or Rs. S/70 per tonne

Explaination

1) The steam requirement has been assessed on the basis of the maximum steam available at the Solvent Extraction Plant. Even this is a slight over estimation. If 800 kg of steam is used the cost of steam will be Rs. 56/- per batch and the parboiling cost will be Rs. 6.63 per tonne,

2) lf 1200 kg of steam is used the cost of steam wi 1- Rs. 24 '- per batch and the parboilinJ co>t w11l be Rs. 127.50 for I 5 tonnes and Rs. 8. 50 per tonne.

P'ol. IX, No . 4 49 3. The pay of the helper is reckoned on the basis of Rs. 5/- per batch. Actually this is the salary per diem for the helper. At least 3 batches can be produced per day. If this is taken into consideration the cost of the helper will be Rs 1.66. for a 15 tonnes batch

4. Taken on the basis of 800 kg of steam and Rs. 166/- for helpers wages per batch, the cost will be Rs 48.56 for tonnes and Rs. 3.24 approximately per tonne.

b) Drying Process

Drying cost per tonne using LSU Oil fired drier and taking 7 hours for drying 5 tonnes (actually 5 hrs of drying are suffi­ Rs. 12-80 only if Rs. 6/- are allowed cient) Each hour of drying requires 30 for any contingencies) the cost per Jitres of oil costing 30-5 Paisa per litre and tonne may be taken at Rs. 18-80) 7 hours needs 210 litres costing Rs. 64-05

c) Total parboiling and drying cost using LSU drier and reckoning drying time at 7 hrs Rs. 24 - 50 per tonne. and the pay of helper at Rs. 5/- per batch.

NB :- I) The cost of parboiling and dry­ ing using 800 kg of steam and Rs. 25 - 40 per tonne 7 hours of dryi~g

2) Jhe cost of parboiling and dry­ ing using 1,200 kg of steam and Rs. 28 - 26 per tonne. 7 hrs of drying.

APPENDIX-E

If a husk fired boiler is used, the cost of the fuel can be reduced to 20% of the oil fired boiler, calculated on this basis the cost of steam for parboiling can be reckoned on the following times.

a) Using 600 kg Rs. 8.40 per batch of 15 tonnes. b) Using 800 kg Rs. 11.20 per batch of 15 tonnes. c) Using 1200 kg Rs. , 16.80 per batch of 15 tonnes.

On this basis and reckoning the wages of the helper at Rs. 1.66 per batch the cost of parboiling will be :-

50 J. Agri/. Engg. a) Using 600 kg of steam Rs. 48-06 per 15 tonnes and Rs. 3.20 per tonne b) Using 800 kg of steam Rs. 50-86 per 15 tonnes and Rs. 3.39 per tonne c) Using 1200 kg of steam Rs. 56-45 per 15 tonnes and Rs. 3.76 per tonne

If drying is d ;>ne in LSU type of drier using oil, take 7 hours and the total drying cost is reckoned at Rs. 18.80 per tonne the total cost of parboiling and drying will be :-

a) Using 600 kg steam :- Rs. 21.00 per tonne. b) Using 800 kg steam :- Rs. 22.90 per tonne. c) Using 1200 kg steam:- Rs. 22.57 per tonne.

REFERENCES

D.K. Mecham, Kestner and Pense : Parboiling characteristics of Calif01nia Medium -grain rice (U.S. Dept. of Agriculture, Western Regional Research Laboratory Albany 10 California) Food Tochnology, Vol. No. 11 pages 475 - 479, 1961.

Vol. IX, No. 4 51