C H A P T E R 5

C O N C L U S I O N S

Rice bran contains approximately 12 - 2 5 % oil, depending on the variety of the bran.

Solvent extraction is an effective method for rice bran oil extraction and in average

approximately 98 wt% available oil is extractable.

Rapid lipolysis is the major constrain in rice bran oil extraction. It was demonstrated that

lipolysis and hence the growth of FFA content depend on the moisture content in the

bran. Rice bran generally contains about 10 - 13% moisture, which depends on the

relative humidity of the environment. Therefore the moisture content of the bran should

be maintained below 5 % (dry basis) while storing for extraction. Rice bran reaches the

equilibrium with surrounding moisture and equilibrium moisture content depends on the

relative humidity of the atmosphere.

Thus stabilization of bran is extremely important. Steaming, hot air drying in a fixed bed

or a fluidized bed, refrigeration and chemical stabilizations are effective methods of bran

pretreatments. Despite the fact that the solar drying is the cheapest method, the rate of

drying is slow and it depends on the climatic conditions and hence not effective way of

stabilization. In addition to inactivation of lipase steaming enhances the oil extractability

and comparatively cheaper and practicable method compared to other effective methods.

Hence steaming is the most effective and suitable for stabilization of rice bran.

Parboiled bran has lower rate of lipolysis compared to the raw bran and this is due to the

of parboiling treatments inactivation of the lipolytic activity during boiling. Further the

parboiled bran has higher amount of extractable oil content.

Extraction temperature is an important aspect for solvent diffusivity through bran and

elevation of temperature comparatively increases both rate of solution of solute in solvent

92

and rate of diffusion of solute through the solvent. Therefore it leads to an increased rate

of extraction. But high temperature extracted oil is darker in colour and causes difficulties

in refining of the oil. Wax content in the oil is higher at high temperature operations and

may be desirable for some industries.

Average particle size in bran is approximately 400 urn. Pellatization of bran avoids

difficulties in separation of extract and raffinate, contamination of the oil with fines and

solvent channeling. However, extraction process is more efficient with small size pellets

due to increase in surface area available for mass transfer. Diffusion of hexane through

the bran shows rate of mass transfer from the surface of bran particles is directly

proportional to the surface area of solid liquid interface.

Use of alternative solvents was considered using iso propyl alcohol (IPA) and water as

solvents. IPA and hexane extractions showed similar extractable conditions and similar

qualitative analysis. However the rate of extraction for IPA was slightly less than that of

hexane. Aqueous extraction results 80 wt% oil and the oil is pale in colour, due the low

solubility of colour pigments in water at the operating conditions. Despite the fact that

aqueous extraction avoids some disadvantages of solvent extraction such as

contamination of oil with the solvent, high cost of organic solvents etc. disposal of highly-

basic effluent and separation of raffinate and extract phases should be addressed.

Equilibrium characteristics for the rice bran oil - hexane - iner t system shows

approximately a constant inert/solvent ratio in the underflow and no preferential

adsorption of oil or solvent to the used bran. Equilibrium properties determined for raw

and parboiled rice bran can be used for process equipment design calculations. Diffusion

coefficient of rice bran oil in hexane has been determined experimentally and can be used

for batch extraction calculations and modeling purposes.

Rice bran fatty triglycerides are higher in molecular weight and hence it has a high

boiling point around 350 °C. Therefore these fatty triglycerides can not be distilled easily

and changes due to pressure variation is comparatively smaller.

Analysis of oil showed an increase in Iodine value and Saponification value due to

refining. The values are comparable with other commonly used vegetable oils.

Extraction of raw rice bran oil using hexane as the solvent has been addresses by this

work to a great extent. Hence as a result of the present investigation optimal operating

conditions and equilibrium characteristics for rice bran oil extraction using hexane

available in Sri Lanka have been determined. Number of suggestions can be made in

order to improve this work.

I. To carry out more aqueous extraction experiments under a range of operating

conditions for more varieties of rice bran.

II. To develop a suitable method of treatment for effluent in aqueous extraction.

III. To fractionate rice bran oil and purify to obtain components suitable for

pharmaceuticals etc.

IV. To develop a computer model to determine optimal operating conditions for a

batch extraction process.

94

REFERENCES

1) Abhay, S. D; Agrawal, B. K., Shukla, L. S; 'Influence of pellet size on

extraction', JAOCS, ( 1983), p 465.

2) Adir, D; Rice Bran stabilization, UNIDO document February, (1967).

3) Aggraval,V.S; Status report, Rice by-products conference, Valencia, Spain,

(1977), p 57.

4) Aggrawal V.S., Rice By products conference Valencia. Spain, (1977), p57.

5) American oil Chemist Society, Official and tentative methods of AOCS

International, 16 t h edition, (1995).

6) Bernadini, E; Oil seeds Oil and Fats, vol I, chapter XII, 463-473, (1982).

7) Bernnan, J. G., Butters, J. R., Cowell, N.D., & Lilley, A.E.V., Food Engineering

operations, 3 r d edition, Elsevier Science pub. Co. Inc. New York, (1990).

8) Bhattacharyya, A.C; Bhattacharyya, D.K.; Deacidification of high FFA rice bran

oil and reesterification and alkali neutralization, JAOCS,(1987)., pp 15-18.

9) Bhattachryya, D.K., De.B.K., Physical refining of rice bran oil in relation to

degumming & dewaxing JAOCS, (1988), p 1683.

10) Browne, jr. C. A; Journal of American oil Chemist Association, (1903), p 948.

11) Burns, H., Cassedy, M.M., Method of treating rice bran and rice polish. U.S.

pa tent , 2610. 914,(1952).

95

12) Cater, C M . , Rhee, K. C , Hagenmaier.R.D., 'Aqueous Extraction -Alternative oil

seed milling Process', J. of American Chemical Society, (1974), pp 137-141.

13) Coulson., J.M.; Richardson., J.F., Chemical Engineering, Particle technology and

separation processes, Volume 2, New York, Pergamon Press, (1991).

14) Cruz, A. O., West A.P. and Aragon, V.P., Composition of Phil ippine Rice oil.

Philippnes Journal of Su. 48, (1982), pp 5-12.

15) Dollear, F. G; Swift, C.E; Pore, P; 'The stability and processing characteristics of

some rice bran', JAOCS, (1950), pp 14-19).

16) Draft Stady of rice bran stabilization technology Applied Science Research

ciiperation of thailand, UNIDO Group Working document, (1967).

17) Dutta, B.K., De, B.K.. Das, R., Bhattcharyya, D.K. Membrane degumming and

dewaxing of rice bran oil, chemical abstract 100(a), ,(1998), p 416.

18) Goenka O.P. Nutritional Significance of RBO Sec ix , processing & utilization of

products, Solvent extractors association of India, (1987).

19) Grist, D. H; Rice, fifth edition, chapter 20, p.499, Longman, London, (1985).

20) Hagenmaier,R.D., Aqueous extraction of full fat sunflower seeds. J. of American

Chemical Society, (1974), pp 470-471,

21) Hand book on rice bran - processing & utilization of products, India, Solvent

extractors association of India, (1987).

22) Hanmoungjai,P..Pyle,L., Niranjan, K, 'Aqueous extraction of rice bran oil". .1.

chemical technol biotechnol, (2000) ,pp 348-352.

23) Horace ,D.C, Baird, H.W., Nowell, J.H., Getzer, F.W., Laboratory manual of

physcical chemistry, John Wiley & sonc Inc. USA, (1975).

24) Johnson, L.A., Lusas.E.W., Comparison of alternative solvents for oil extraction.

JAOCS,(1983), PP 229-242.

25) Julian, F; Hoffpauir, C. L; 'Lipid content of rice bran, J. of American Oil Chemist

Society", (1951), p 23.

26) Kachru M.P, Rice By products conference Valencia. Spain, (1977), p 66.

27) Krishna,G.A.G; A method of bleaching rice bran oil with silica gel, JAOCS, 69,

(1992), ,pp l257-1259.

28) Ktiya, T., Japan Agricultural Research Quar Terly, (1967), Pp 2-7.

29) Kuk, M.S., Doud M.K., 'Supercritical COi extraction of Rice bran oil, JAOCS

, ( 1 9 9 8 ) , p p 623-628.

30) Lee, S.B., Park, K..A., Isolation of functional fatty acids from rice bran in co-

solvent induced SFE process, J. of American Chemical Society,(1999), pp 438-

444.

31) Menike. W.W., Harris W.D. Solvent extraction of rice bran. JAOCS , (1949). pp

532-534.

32) Minsh S.K, Kakar, A., Surnua, P.S., 'Efect of different degumming agents on the

physico chemical characterstic of rice bran oil' j . Food sci. Technol. (1990). 280-

283

97

1

33) Moreau, R.A., Powell, M.J., Quantitative analysis of triacylglycerols and other

lipid classes in edible oils and fats via HPLC, American chemical society. (1999).

34) OzguLS., Turkay,S., 'In situ esterification of rice bran oil with methanol &

ethanol' , JACOS, (1993), pp 145-147.

35) Pillaiyar, P; Journal of Oil Technological Association India, (1980), p.-42.

36) Prabhakar, J.V; 'Stabilization of bran', processing & utilization of products, India.

Solvent extractors association of India, (1987).

37) Prabhakar, Jr, Venkatesh K,V.L., 'Chemical Stabilization of rice bran JAOCS.

(1986), p 644,

38) Procter, A; Bowen, D. J; 'Ambient temperature extraction of rice bran oil*,

JAOCS, (1996), pp 811-813.

39) Procter, A; Jackson V.M; Scott, M; Clark, P. K; Rapid equlibrium extraction of

rice bran oil, JAOCS, ( 1994), pp 1295-1296.

40) Rao, S.D. ;Panduranga, B. R; Ahamed, S.A;. T; Indian Oil and Soap Journal, .

(1967). vol 32, p 203.

41) Sachru P.S., Rice By products conference Valencia. Spain, (1977), p 53.

42) Sarada, P.S; Status report, Rice by-products conference, Valencia, Spain. (1977).

43) Sayre, R.N., Nayyar , D.K., Saunders, R.M., Extraction & Refining of Edible Oil

from extrusion stabilized rice bran. JAOCS, (1985), p i040 .

y <)8

44) Soares, V.J., Non edible uses of rice bran oil & its derivatives. Hand book on rice

bran - processing & utilization of products. Solvent extractors association of

India, (1987).

45) Solar rice bran stabilizer, Karmantha, (1987), pp 27-28.

46) Taira G. & chang W. J.of Agric. Food Chemistry. (1986), p.502.

47) Testing methods for chemical products, Japanese industrial standards, (1978).

48) Teuge R,0 . , Reddi , B.V., Rice Bran oil utilization as an edible oil JAOCS,

(1949), pp 349-352.

49) Teuge, R.O;Reddi,B.V; Rice bran oil utilization as an edible oil, JAOCS, (1952),

pp349-352.

50) Thiumala , Rao, S.D., A Survey of rice bran oil industry in Various Countries

Indian oil seed journal, (1961), vol 5, pp 121-132.

51) Williams, L; Bear, S; 'Expansion and extrusion of rice bran', JAOCS, ( 1965).

pi 51 .

52) Yokochi, K; 'Rice processing for the production of rice bran oi'l .. status report ,

Rice by products utilization, international conference III, Valencia, Spain. (1974).

53) Yoon, H,S., Kim, S.K., Oxidative Stability of High FFA rice bran oil at deferent

stages of refining. JAOCS, (1994), pp 224-229.

APPENDIX I

Range Protein (%) Fat (%) Fiber (%) Ash (%) | NFE (%) Minimum 6.7d ; 11.5 4.7d ; 12.8 6.2 8.0 33.5 Maximum 17.2 25.6 14.4 ; 26.9d 17.7 ; 22.2d 53.5

(d - Huller type mi l l ) Table-l .-l : Rice bran composition (dry basis) (Extracted from Ref. Hand book on Rice Bran [21]

Percentage

Unsaturated fatty acids - 80 - 85 % Saturated fatty acids - 1 5 - 2 0 % Myristic acid - 0.4 - 1.0 % Palmiric acid - 1 2 - 1 8 % Stearic acid - 1 - 3 % C 2 0 - C 2 2 saturated - 1 % Oleic acid - 40 - 50 % Linoleic acid - 29 - 42 % Linolenic acid trace - 1 % Palmiroleic - 0.2 - 0.4 %

Total tocopherol content - 3 8 . 8 m g / 100 g oil (vitamine E) ( a- 32.2mg ; y - 2.5 , (3 - t race) Squalene (C30H50) - 4 0 0 m g / lOOg oil Oryzanol (ferulic acids) - 1 - 2.5 % of crude rice bran oil Lecithin (phosphatides) - 0.75 - 1 % of crude rice bran oil Wax (Esters of long chain FA)- 1 . 5 - 4 % of crude rice bran oil

Table I - 2: Composition of Rice bran oil [5]

Specific gravity at 25c 0 .916 -0 .921 Refractive index at 25c 1 .470- 1.473 Iodine number 9 0 - 1 0 8 Saponification number 181 - 189 Unsaponifiable matter 3 - 5 % Titer 2 4 - 2 8 c Acid value 4 - 1 2 0

Table I.-3. Characteristics of rice bran oil [21 ]

Solvent Boilin g Pt.°C

Latent heat of Vap. (Cal/g )

Sp. Heat (cal/ g °C)

Sp. Gravit y 20 °C

Liquid Viscos itv 20 °C

Surface tension (dyne / cm)

Dielec trie consta nt

Flash point °C

Water Solubil itv 25 °C (g/1)

Hexane 69.0 79.9 .0533 0.659 0.312 18.40 1.89 -23 0.05

IPA 82.5 159.3 0.596 0.786 2.4 20.8 18.6 1 1.7 INF

Water 100.0 540.1 1.018 1.000 1.005 72.75 80.36 NF -

Table I.-4: Chemical And Physical 'roperties of Solvents [24]

Characteristics Requirements 1 Distillation

i. Initial boiling pt. °C min. 63 ii. Dry pt. . °C max. iii. Temperature change for final 10%. °C max.

70 2

2 Composition i. Aromatics % by volume, max. 1.0 ii. Saturates % 98.5

3 Density at 25. U C max. 0.687 4 Colour (saybolt), min. +30 5 Sulphar content 75 6 Corrosion level, Copper strips, 3hr, 50°C 1 7 Lead g. per liter, max. 0.0005 8 Phospate, ppm, max. 20 9 Chlorides, (as CI),ppm, max. 20 10 Bromine no. max. 1 11 Non volatile residue, g. / 100 ml, max. 0.001

12 Reaction of non volatile residue to Methyl orange Pink/ red should not be

formed Table 1-5: Requirements of food grade hexane I.S. 3470. 1966

APPENDIX II

Rice producing countries

in Asia

Rice Productio

n ( ' 0 0 0 tons

)

Rice bran oil

potential ( ' 0 0 0 )

Rice producing countries

in Asia

Productio n

( '000 tons )

Rice bran oil

potential ( '000 tons )

Banglades h

26778 380.68 Lao DPR 1491 26.81

Bhutan 43 0.64 Malaysia 1960 24.66

Cambodia 2500 48.45 Myanmar 13972 217.71

China 191615 2556.36 Nepal 3502 47.30

India 111517 1672.80 Pakistan 4891 87.98

Indonesia 45179 631.56 Philippine s

9885 145.20

Japan 13124 146.23 Sri Lanka *

2538 34.32

Korea, DPR

3570 29.87 Thailand 17193 296.72

Korea, republic

7722 92.70 Vietnam 19225 400.27

Total Asia 479480 6892.92 Total World

520053 7605.18

Table II.-1 : World potential rice bran oil production Source : International Rice Research Institute

Variety Year

released Age group

months Variety Year

released Age group

months

Bg 407 1981 5 - 6 Bg352 1992 3 - 3 Vz

Bg 745 1981 5 - 6 Bg357 1997 3 - 3 Vz

B g 3 8 1981 5 - 6 Bw 266-7 1981 3 - 3 Vz

Bg 400-1 1980 4 - 4 Vz Bw 267-3 1981 3 - 3 Vz

Bg 379-2 1980 4 - 4 1 / 2 Bg351 1986 3 - 3 Vz

B g 3 8 0 1982 4 - 4 Vz At 353 1992 3 - 3 Vz

B g 4 5 0 1985 4-AVz At 35 1992 3 - 3 Vz

B g 4 0 3 1993 4 - 4 y 2 At 355 1992 3 - 3 Vz

Bw 451 1987 4 - 4 1 / 2 Bg300 1987

Bw 400 1987 4 - 4 1 / 2 Bg301 1987 ~>

Bw 452 1992 4 - 4 1 / 2 Bg304 1981

Bw 453 1992 4 - 4 1 / 2 Bw 272-6B 1981 ->

At 401 1992 4 - 4 Vz Bw302 1987 ->

At 402 To be released

4 ^ Vz At 303 1990 -» j

B g 3 5 0 1986 3 - 3 Vz Bg750 1981 2 - 2 Vz

Table II-.2: Rice varieties released by the Department of Agriculture Sri Lanka sinel^l IF 1 Bg - Batalagoda, Bw - Bombuwela. At - Ambalantota

* Production zone Harvested area

( % harvested area )

* Production zone Harvested area

( % harvested area )

Am para 13 .06% Matale 2.55 %

Kurunegala 10.98 % Kegalle 2.52 %

Polonnaruwa 9.46 % Udawalawe 2.52 %

Matara 6.35 % Puttalam 2.35 %

Hambantota 5.20 % Gampaha 2.17 %

Baticola 5.06 % Nuwaraeliya 1.63 %

Anuradhapura 4.50 % Moneragala 1.61 %

Galle 4.22 % Killinochchi 1.09 %

Kalutara 4 . 1 4 % Colombo 1.03 %

Mahaweli H 3.95 % Mullativu 0.84 %

Kandy 3.80 % Jaffna 0.74 %

Trincomalee 3.69 % Mannar 0.26 %

Badulla 3.53 % Vavuniya 0 . 1 6 %

Table II.-3: Rice production Zones in Sri Lanl-Source : International Rice Research Institute

ca

APPENDIX III

Edible Non Edible 1. Hydrogenated Products 2. Cooking & Salad Oil 3. Phameceuticals (tocopherols, Squaline, Oryzanol, etc)

Agro-Industry Hydrogenated Fatty acids

1. Pesticide 1. Synthetic Formulations Rubber

2. Dispersing 2. Cosmetics Agents Formulations

Distilled fatty acids Soap & Detergents

1. Poly Hydric Alcohols

2. Dimer Acids 3. Textile Auxiliaries

Bio Degradables 1. Alfa Olefine Sulfonates

Paint Industry 1. Emulsifying Agents 2. Anti-rusting Agents 3. Protective coatings 4. Plastiziers 5. Adhesives

Industrial Applications of rice bran oil [21

Rice Bran oil