Isolation and identification of indigenous microorganisms and its application in fermented corn and characterization of physicochemical properties of the flour
Isolasi dan identifikasi mikroorganisme indigenus dan aplikasinya pada fermentasi jagung serta karakterisasi sifat fisikokimia tepung yang dihasilkan
View/ Open
Date
2013Author
Rahmawati
Hariyadi, Purwiyatno
Fardiaz, Dedi
Dewanti-Hariyadi, Ratih
Metadata
Show full item recordAbstract
Corn is an important carbohydrate source in Indonesia. Local white corn is currently being developed including Anoman 1 (high amylose) and Pulut Harapan (low amylose) varieties. However, the utilization of corn flours and/or starches in native form have a less desirable physicochemical properties, especially with regards to retrogradation, syneresis, and low stability of pasta at high temperature and low pH properties. Consequently, there is a need to modify flour properties to increase the utilization. Traditionally, corn flour is made by soaking corn kernels in water. The spontaneous fermentation occurred during soaking and affected the physicochemical properties, but it’s difficult to achieve a consistent product. The purpose of this study to identify microorganisms that play a role in the fermentation process of corn, as well as the process of fermentation with the addition of a starter culture and studied the physicochemical properties of corn flour produced. The research was conducted in : (1) to isolate and identify microorganims which the role play during spontaneous fermentation of white local corn of Anoman 1 variety; (2) to design a starter culture of the microorganisms isolated to use for a controlled fermentation; (3) do the fermentation by adding a starter culture and characterize physicochemical properties of corn flour produced. Treatments consisted of: Spontaneous fermentation, i.e. water soaking of corn grits (as a control, SF); and fermentation with added starter culture containing microbes previously isolated without toxigenic microbe (CC); and (AC) fermentation of (CC) with additional amylolytic microbes after 16 hours of fermentation. The number of each microorganisms that added were 106 CFU / mL; (4) to study the physicochemical properties of corn flours of Anoman1 and Pulut Harapan varieties produced. Observations were done at 0, 36, 48, and 72 hours fermentation. The results showed that there were 16 microorganisms were identified included 8 species of molds (Penicillium chrysogenum, Penicillium citrinum, Aspergillus flavus, Aspergillus niger, Rhizopus stolonifer, Rhizopus oryzae, Fusarium oxysporum, Acremonium strictum), 3 species of yeasts (Candida famata, Kodamaea ohmeri, Candida krusei/incospicua), and 5 species of lactic acid bacteria, LAB (Lactobacillus plantarum1a, Pediococcus pentosaceus, L. brevis1, L. plantarum1b, and L. paracasei ssp paracasei3). Four molds and one yeast were amylolytic while none of the lactid acid bacteria (LAB). One from 8 species of molds identified was producing aflatoxin i.e. Aspergillus flavus. While all of yeasts and LAB species identified was non-toxigenic. So, the Aspergillus flavus was not used as a starter culture. All of non-toxigenic microbes identified, there were three (3) species of mold (Penicillium citrinum, Aspergillus niger, Acremonium strictum) and one (1) species of yeast (Candida famata) that were amylolytic, while all of LAB identified were non-amylolytic. The amylase activity changed during spontaneous fermentation (SF), where the activity was a maximum at 12 hours of fermentation. After that activity tended to decrease up to 72 hours of fermentation. To study the influenced of amylase activity to the flour during fermentation, was made the amylolytic culture that added after 16 hours fermentation to increase the activity . In general it can be concluded that the fermentation process caused the changes in the physicochemical properties of corn flour. Fermentation with the addition of a starter culture, either (1) a complete culture, i.e. microorgaisms cultures consisting of all types of microbes were identified, except Aspergillus flavus (CC) and (2) CC fermentation with the addition of amylolytic culture (culture consisting of molds and yeast amylolytic ) after 16 hours fermentation (AC), increased the number of molds and yeasts in the beginning process of fermentation up on 72 hours of fermentation, compared to the number of molds and yeasts in spontaneous fermentation (SF), but the addition of a starter culture is only increasing the number of LAB at the beginning of fermentation and did not after 36 hours until the end of fermentation. Concluded that spontaneously, LAB growth is already high enough so that the addition of LAB starter cultures had no effect on the number of LAB during fermentation. The number of BAL correlated with the pH value of water and the pH of corn flours produced, thus affecting some physicochemical properties The fermentation process caused to reduce protein, fat, ash and crude fiber contain from white corn of flour Anoman 1 and Pulut Harapan varieties. Enzyme activity during the fermentation decreased in amylose content of Anoman 1 four, but the 36CC fermentation and 48CC tended to increase the amylose content of Pulut Harapan flour. The 72 hours fermentation process affected the pasting properties of white corn flour of Anoman 1 dan Pulut Harapan varieties resulted, i.e. increased the peak, breakdown, final, and setback viscosities. AC resulted in corn flour of Anoman I (high amylose) with lower values of peak (PV), breakdown (BV), final (FV), and setback viscosities (SV) than U, SF and CC. While for corn flour of Pulut Harapan variety (high amylopectin), AC fermentation resulted in flour with higher value of PV, BV, FV, and SV than U, SF and CC. AC treatment could improve the stability of pastes of flour that contain high amylose (Anoman 1) during cooling, but instead lowers the stability of pastes of flour that contain high amylopectin (Pulut Harapan) when cooled, except the flour of Pulut Harapan that treated 72AC. Pulut Harapan flour that has been treated 72AC resulted the final viscosity and setback viscosity lower than 72SF and 72CC. The 72AC treatment seemed to increase the stability of the pastes containing high amylose starch during heating and cooling, but instead lowers the stability of pastes containing high amylopectin during heating and cooling for up to 48 hours. At 72 hours of fermentation treatments flour paste 72AC improve stability during cooling. The fermentation process affected the physical properties of flour produced, where the addition of a starter culture tended to increase the gel strength of Anoman 1 flour during fermentation where the effect of the gel treatment AC higher than CC that higher than SF. The gel strength of the Anoman 1 flour tended to be higher than Pulut Harapan. It is associated with a high amylose content in starch Anoman 1. Fermentation time tended to increase the stickiness of the gel, but the addition of a starter culture (CC and AC) tended to decrease the stickiness of the gel from Pulut Harapan flour, where the addition of AC treatment resulted a higher reduction than CC. Fermentation time tended to increase the whiteness degree of the two varieties of white flour with the decreased in protein content. Water absorption capacity seemed to increase during fermentation especially Anoman 1 flour and oil absorption capacity tended to decrease during fermentation.