Yetti Mulyati Iskandar, Sri Priatni and L.B.S. Kardono
Jl. Sangkuriang 21/154
ABSTRACT
Oncom is a product prepared by fermenting cooked peanut presscake as substrate mixed with tapioca flour using Mucor sp as inoculum. The aim of this research is to determine the chemical composition and nutritional contents of black oncom using lupine (Lupinus angustifolius) and pigeon pea (Cajanus cajan) as substrate instead peanuts ( Arachis hypogaea ) to evaluate its potential as a new source of protein. The moisture content, pH, texture, solidness, hardness, mold growth and colour of black oncom fermented product were observed. Various tapioca flour concentration in amount of 5%, 20% and 35% respectively were mixed on peanuts, lupine and pigeon pea as substrates. The fermentation process was conducted for 48 hours at 300C.The result revealed that the addition 20% of tapioca to substrate showed the best performance of black oncom product and had good sensory characteristics such as texture, taste, aroma and colour based on the sensory evaluation test.
Keywords: black oncom, tapioca flour, Lupine, Mucor sp.
ABSTRAK
Oncom merupakan hasil fermentasi substrat kacang tanah yang di campur tepung tapioca dengan menggunakan Mucor sp sebagai inokulum. Tujuan penelitian ini adalah untuk menentukan komposisi kimia dan kandungan nutrisi dari oncom hitam yang menggunakan kacang lupin (Lupinus angustifolius ) dan gude (Cajanus cajan ) sebagai substrat pengganti kacang tanah ( Arachis hypogaea ) dan mengukur potensinya sebagai sumber protein baru. Penelitian meliputi kadar air, pH, tekstur, kepadatan, kekerasan, pertumbuhan kapang dan warna oncom hitam hasil fermentasi. Variasi konsentrasi tepung tapioca 5%, 20% dan 35% dicampur dengan kacang tanah, lupin dan gude. Proses fermentasi dilakukan selama 48 jam pada suhu 300 C. Hasil penelitian menunjukkan penambahan tepung tapioka 20% menghasilkan produk oncom hitam terbaik dan memiliki karakteristik seperti tekstur, rasa, aroma dan warna berdasarkan hasil evaluasi cita rasa.
Kata kunci : oncom hitam, tepung tapioca, Lupin, Mucor sp
INTRODUCTION
Oncom is one of the well known traditional Indonesian foods and is a product of fermentation made from peanuts presscake as its main ingredient, along with other ingredients such as tapioca waste material and tofu waste material. The fermentation process utilizes certain types of moulds to produce oncom from peanuts. Oncom can be distinguished into 2 types based on the types of molds used, namely black oncom and red oncom. Black oncom is made using Mucor sp. mold, whereas red oncom is made using Neurospora sp mold [1].
Peanuts presscake is the main ingredient commonly used to make oncom. This is due to the fact that as much as it is a waste product, peanut presscake is still high in nutrients to be exploited as dietary ingredient. Apart from its nutrients, using peanut presscake is also more economically viable option in comparison to using peanuts. As a result, to minimize the production price, producer prefers using peanuts presscake to using peanuts as a main ingredient in the production of oncom [2]. In reality, there are several other legumes which can be obtained with competitive pricings such as lupine and pigeon pea. Australian sweet lupine ( Lupinus angustifolius ) is one of the legumes that grow mainly in Australia Indonesia Indonesia
The aim of this research is to determine the chemical composition and nutritional contents of black oncom by using lupine (Lupinus angustifolius) and pigeon pea (Cajanus cajan) as substrate instead peanuts (Arachis hypogaea) to evaluate its potential as a new source of protein.
MATERIALS AND METHODS
Materials :
Ingredients used to produce the black oncom were pure Mucor sp. culture, peanuts (Arachis hypogaea), lupine (Lupinus angustifolius), pigeon pea (Cajanus cajan), tapioca flour and banana leaves. Microorganisms such as Mucor sp was used as inoculum. Tools used consisted of those of the actual tools required in the production of black oncom and those used for analytical purpose.
Preparation of Oncom
Black oncom was produced by using various substrate, namely peanuts, Australian sweet lupine, and pigeon pea, as well as various concentrations of tapioca flour i.e 5%, 20%, and 35% respectively as an additional ingredient. Firstly, dehulled peanuts were soaked into water for 24 hours, followed by sieving and coarse grinding. Tapioca flour was then added according to the required concentration, followed by mixing. Next, sterilization was carried out in an autoclave at 105oC for 20 minutes. Subsequently, after cooling the substrate was inoculated by sifting Mucor sp. to the cooked peanuts surface for as much as 0.1% of total weight. Fermentation was carried out for 2 days at room temperature (25o – 30oC). The first day, the moulds were enclosed within banana leaves, whereas on the second days the molds were left open [6].
Analysis
Several different analysis were performed from day 1 to days 6, namely water content [7], texture measurement (LFRA Texture Analyzer), visual examination using a 1-5 scoring system such as solidness, hardness and imaging color ( spectrophotometer ). Proximate analysis was carried out on the main ingredient ( peanuts, lupine and pigeon pea oncom ) and organoleptic test ( hedonic test ) were performed for the best oncom [8].
RESULTS AND DISCUSSION
In this research, water content ( wet basis ) of black oncom is measured during 6 days by taking 5 gram sample and dried using oven method. The result was presented in table 1. During the fermentation process, the water content dropped due to the growth of mold Mucor sp which caused alteration in the chemical components of the substrates.
Table 1. Statistical Result of Legumes Type
Legumes | pH | Water Content | Texture ( g/cm2 ) |
Lupine oncom | 6.73a | 63.51a | 831.23c |
Peanuts oncom | 6.47b | 30.76c | 1533.73a |
Pigeon pea oncom | 6.42b | 58.93b | 970.87b |
Tapioca Flour (%) | pH | Water Content | Texture |
5 | 6.67a | 52.57a | 864.57c |
20 | 6.55b | 50.59ac | 1183.57b |
35 | 6.41c | 50.03bc | 1287.70a |
Note: superscript in the same column with same letter showed no significant difference at α= 0.05
It can be seen that there was an increase on the pH of black oncom during the fermentation process. The enzymes which have the important role in food fermentation by mold is amylolytic and proteolytic enzyme, which breaks down starch and protein in the substrate. The pH increase may be caused by the activity of proteolytic enzyme produced by mold which breaks down protein to amino acids. Further degradation of amino acids will generate free ammonia, thus increasing the pH.
Carbohydrates and organic acids are hydrolyzed by molds which in an aerobic condition will generate carbondioxide and water [10] . However, in the fermentation process evaporation also occurs due to the generation of heat and the flow of air, both of which may reduce the water content of the resulted oncom.
According to statistical test, the water content of black oncom with 20% tapioca flour is not significantly different from the water content of black oncom with 5% and 35% tapioca flour. However, the water content of black oncom with 5% tapioca flour is significantly different from the water content of black oncom with 35% tapioca flour. The statistical test also indicated that types of legumes used will affect the water content of the black oncom. Lupine black oncom has the highest water content, followed by pigeon pea, then peanuts. This occurrence may be possible because under the same soaking period, lupine legume absorbs more water resulting in higher water content in comparison with other legumes.
Texture of black oncom is measured using LFRA texture analyzer which is commonly used to measure the texture. The increase of the texture score which indicates an increase of hardness of black oncom, until the fermentation process finish (48 hours). The hardness of texture of black oncom is affected by the affinity of mycelium which crosses and bundles the legumes to form a dense union. Further growth of mycelium Mucor sp would cover the legume, resulting in a more unified oncom texture. The hardness of oncom’s texture may also caused by a decrease in water content. The statistical test indicated that the types of legumes and the concentration of tapioca flour affect the texture of black oncom produced and there is an interaction between both the legume types and tapioca flour concentration towards the texture of black oncom. Peanuts have the highest texture value, whereas lupine has the lowest texture value. This may be possible because of the higher water content found in lupine, contributing to the softer texture found in the lupine-produced oncom. Statistical test showed that concentration of tapioca flour affect the texture of oncom produced. The texture of oncom added with 35% tapioca flour has the highest score, where as the texture of oncom added with 5% tapioca flour has the lowest score. Higher flour concentration may cause the oncom to be denser, thus producing harder and more compact texture.
Solidness is one of the parameter used in this research to observe the texture of product whereas a solid product will have a solid and dense texture. Solidness measured was based on the visual supervision using the range of score 1 until 5. The higher the score indicates an increase intensity of solidness. The statistical results of legumes was presented in table 2. The increase of solidness occurred every day , because of the increase of growth of mold which crosses and bundles the legumes to form a dense union an cause an increase in solidness. The higher concentration of tapioca flour used, the solidness of product will increase because the legumes will become more attached one to another, resulting in more solid and dense texture.
The statistical test showed that the types of legumes do not affect the solidness. The addition of 5% tapioca flour has the lowest solidness score and has a significant different with the solidness of black oncom added with 20% and 35% tapioca flour, but the addition of 20% tapioca flour don’t have significant difference with 35% tapioca flour.
Table 2. Statistical Result of Legumes Type
Legumes | Solidness | Hardness | Growth of Mucor sp |
Lupine oncom | 2.83a | 2.83c | 4.67a |
Peanuts oncom | 3.50a | 4.67a | 3.00b |
Pigeon pea oncom | 3.33a | 3.50b | 4.50a |
Tapioca Flour (%) | Solidness | Hardness | Growth of Mucor sp |
5 | 2.50b | 3.17b | 3.83a |
20 | 3.33a | 3.83a | 4.00a |
35 | 3.83a | 4.00a | 4.33a |
Note: superscript in the same column with same letter showed no significant difference at α= 0.05
. This may be because of the increase in tapioca flour used, the legume will become more attached one to another resulting in the increase in solidness compared to the solidness of oncom added with 5% tapioca flour.
Measurement of black oncom texture especially hardness was conducted by using LFRA texture analyzer, the measurement of the hardness level by visual supervision using the range of score 1 until 5. Measurement of black oncom texture especially hardness can be seen in figure 1, 2 and 3. The increase of score indicates the increase of hardness level.
The hardness level increased until day-3 and followed by a constant trend afterwards. Based on the statistical test, the concentration of tapioca flour of 20% does not provide a significant difference with black oncom produced using 35% tapioca flour. On the other hand, there is a significant difference on the hardness of black oncom between those added with 5% tapioca flour and those added with 20% and 35%; black oncom added with 20% and 35% tapioca flour has higher hardness score. Statistical hardness level indicated that the types of legumes affect the hardness of black oncom produced. Peanuts made into black oncom has the highest mean score in the hardness level, whereas black oncom made from lupine has the lowest mean score. This may be possible because black oncom made from peanuts contain lower water content in comparison with that made from lupine and from pigeon pea so that the black oncom from peanuts product is harder in texture.
 |
| Figure 1. Hardness Level of Lupine Black Oncom for 5 Days Incubation |
 |
| Figure 2. Hardness Level of Peanuts Black Oncom for 5 Days Incubation |
 |
| Figure 3. Hardness Level of Pigeon Pea Black Oncom for 5 Days Incubation |
Spectrophotometer value was carried out by measuring colour spore at the wave length of 500 nm. The graphs was presented in figure 4, 5 and 6. The graphs indicated that various tapioca flour concentration such as 5%, 20% and 35% respectively, mixed with lupine, peanuts and pigeon pea oncom indicated the highest absorbance level on day-2 which is marked by the black colour peak. Meanwhile, the decrease of colour spore intensity occur after day-3.
This occurrence is caused by the fast growth of mould during this period of fermentation which produces a significant amount of spores, thus causing an increase intensity of the black color. According to the statistical test, it can be seen that there is a significant difference of spectrophotometer value between the peanuts-made black oncom with the pigeon pea and lupine black oncom. This may be due to the higher water content of pigeon pea and lupine black oncom in comparison with peanuts black oncom, causing a considerably higher growth of mould in lupine black oncom.
 |
| Figure 4. Spectrophotometer Value of Peanuts Black Oncom for 5 Days Incubation |
 |
| Figure 5. Spectrophotometer Value of Lupine Black Oncom for 5 Days Incubation |
 |
| Figure 6. Spectrophotometer Value of Pigeon Pea Black Oncom for 5 Days Incubation |
Table 3. Statistical Result of Legumes Type of Spectrophotometer Value
Legumes | Spectrophotometer value |
Lupine oncom | 0.75a |
Peanuts oncom | 0.60b |
Pigeon pea oncom | 0.72a |
Tapioca Flour (%) | |
5 | 0.65a |
20 | 0.69a |
35 | 0.73a |
Note: superscript in the same column with same letter showed no significant difference at α= 0.05
Based on the statistical test, with presented in Table 3 the addition of tapioca flour did not show a significant effect on the black oncom spectrophotometer’s parameter, regardless of changes in concentration.
Organoleptic test by using hedonic method has been done for evaluation of the taste, aroma, colour, and texture score from the best oncom. The black oncom made with substrate lupine, peanuts and pigeon pea mixed with 20% tapioca flour showed the best product. Hedonic scale used in this research is the score ranging from 1 to 7 or dislike to like.
The panel’s average score on the texture of the black oncom showed that there is an insignificant difference between the texture of peanuts black oncom and pigeon pea black oncom. However, the textures of these two types of black oncom are significantly different from the texture of lupine black oncom which the average texture score for peanut and pigeon pea black oncom are higher than lupine black oncom. The statistical test indicated that there is no significant difference of legume types to the taste and aroma of black oncom produced from lupine, peanuts, and pigeon pea. This result showed that different legume types doesn’t affect the panel’s average score to the taste and aroma of black oncom. Based on the statistical test, the average score for the colour of lupine made black oncom has the highest score and significantly different with peanuts and pigeon pea made black oncom. However, the panel’s score for the colour of peanuts black oncom has no significant difference with pigeon pea black oncom. The results from statistical analysis showed that there is no significant difference of overall score between three types of black oncom. This result showed that the use of different legumes types does not affect the overall score. Due to no significant difference in overall score, it could be concluded that black oncom from lupine and pigeon pea can be accepted by the panelist. Proximate Analysis of Black Oncom Products was presented in table 4 . The protein content of peanut oncom was slightly higher, 23.63% compare to lupine oncom 22.76% and pigeon pea oncom 14.86%. Carbohydrate and fat content of lupine oncom was lower then peanuts oncom. Meanwhile, carbohydrate content of pigeon pea oncom was higher compare to lupine and peanuts oncom.
Fermentation of legumes to their oncom products had a lower nutrient contents than their constituent ingredients. Because of molds produce enzymes which hydrolyze carbohydrates, protein, and fat during the fermentation process in order to maintain their growth. The data of proximity analysis of end product, indicated that the protein, fat, and carbohydrates contents are reduced. During fermentation process, the digestibility of the product becomes higher in comparison to its constituents because fermentation hydrolyzes the chemical structures of insoluble substrates to much simpler forms.
Table 4. Proximate Analysis of Black Oncom
Black Oncom Product | Moisture Content | Ash | Protein | Fat | Carbohy drate |
Lupine oncom | 64.40% | 0.23% | 22.76% | 1.33% | 11.28% |
Peanut oncom | 40.72% | 0.88% | 23.63% | 21.34% | 13.43% |
Pigeon pea oncom | 55.06% | 1.52% | 14.86% | 0.68% | 27.88% |
ACKNOWLEDGEMENTS
The authors would like to thank Research Center
CONCLUSION
It can be concluded that types of legumes mixed with various concentration of tapioca flour affect the characteristic of black oncom. Varieties of legumes affect water content, pH, texture, hardness level and solidness also. The result showed that lupine oncom has the highest water content among peanuts and pigeon pea oncom. Meanwhile peanut oncom has the highest texture and hardness. Legumes type gave no significant difference in solidness. The addition of tapioca flour in various concentration gave significant difference in water content, texture, solidness, and hardness. The higher of tapioca flour concentration indicated the lower water content, but the higher texture, solidness, hardness. The black oncom made with substrate lupine, peanuts and pigeon pea mixed with 20% tapioca flour showed the best product. Black oncom made from lupine and pigeon pea can be accepted by the panelist.
REFERENCES
1. Shurtleff W., Aoyagi A.[1980]. Making tempeh starter, Tempeh production, the book of tempeh, vol. II. p. 140 –146.
2. Hesseltine, C.W. dan H.L. Wang. [1972]. Fermented Soybean Food Products. Page 404 – 410 of A. K. Smith dan S. J. Circle, ed. Soybeans Chemistry and Technology. Vol. 1, Chapter 11. The AVI Publishing Co., Inc., Westport , Connecticut
3. Peterson,D.S and A.H. Fair Brother. [1996]. Lupins as a Raw Material for Human Foods and Animal Feeds, Indonesian Food and Nutrition Progress, Vol 3 No 2.
4. Kyle, WSA.[1994]. The current and potential uses of lupins for human food, Dept. of Food Tech., Victoria University of Technology, Melbourne
5. Hesseltine, C.W. dan H.L. Wang. [1972]. Fermented Soybean Food Products. page 404 – 410 from A. K. Smith dan S. J. Circle Westport , Connecticut
6. Hulse, J. H.[1973]. Problems of Nutritional Quality of Pigeonpea and Chickpea and Prospek Research. Ottawa
7. Gunawan ,C. [1977]. Preparation of Powder form Oncom Inoculum. Proceedings of The First ASEAN Workshop on Solid Substrate Fermentation, Bandung , Indonesia
8. AOAC. [1994]. Official Method of Analysis. Association of Official Agricultural Chemist, Washington DC
9. Fudiyansyah,N, D.S.Peterson, R.R.Beel and A.H. Fairbrother. [1995]. A Nutritional,Chemical and Sensory Evaluation of Lupine Tempe
10. Frazier, W.C.[1967]. Food Microbiology. New York
11. .Wang, S.F., Harris,D., and Rotnie,N. [2004]. Nutritionally Benefical Compound from Lupine,GRDC
Tidak ada komentar:
Posting Komentar