This research was aimed to evaluate the pasting properties of white corn flour made from Anoman 1 and Pulut Harapan varieties as affected by the fermentation process of the corn grits. The fermentation process studied were 1) spontaneous fermentation (SF); 2) fermentation with the addition of a complete starter culture at 0 hour (CC fermentation) and 3) fermentation of (CC) with additional inoculation of starter culture containing amylolytic microorganisms at 16 hours (AC fermentation). The evaluation of pasting properties was done on the flour made from corn grits fermented for 0, 36, 48, and 72 hours. Our results showed that pasting properties of corn flour of Anoman 1 and Pulut Harapan varieties were affected by fermentation process. Addition of starter culture in the fermentation showed more complex effect on the pasting properties and was a function of the fermentation time. Fermentation process of corn grits affected the pasting properties of the resulted flour, both for Anoman I and Pulut Harapan corn varieties. The differences in the effect of fermentation process on the pasting properties were due to the different amylose/amylopectin content. AC fermentation of corn grits could increase the stability of paste for flour containing higher amylose content but decrease the stability of paste for flour containing high amylopectin. Specifically, CC fermentation caused significant increase in the peak viscosity value especially for corn flour of Pulut Harapan. Fermentation for up to 48 h had resulted in corn flour of Pulut Harapan variety having a higher PV value, but it did not affect the tendency to retrograde.
Corn is an important carbohydrate source after rice in Indonesia. However, the utilization of corn flours and/or starches in native form is limited due to its physical properties, especially with regard to the retrogradation properties, syneresis of pasta, and low stability of pasta at high temperature and at low pH [
Traditionally, corn flour is made by soaking corn kernels in water followed by the process of draining, drying and milling. Aini et al. (2010) [
Previously, we have identified that microorganisms responsible for the spontaneous fermentation of corn were Penicillium chrysogenum, Penicillium citrinum, Aspergillus flavus, A. niger, Rhizopus stolonifer, R.oryzae, Fusarium oxysporum, Acremonium strictum, Candida famata, Kodamaea ohmeri, Candida krusei/incospicua, Lactobacillus plantarum1a, Pediococcus pentosaceus, Lactobacillus brevis1, Lactobacillus plantarum1b, and Lactobacillus paracasei ssp. paracasei3 [
Since microorganisms were involved in the spontaneous fermentation (SF) of corn, the influence of addition of starter culture to the fermentation process on the pasting property of the resulted corn flour was evaluated. A complete starter culture (CC) was made using all microorganisms indentified responsible for the spontaneous fermentation of corn [
Three experiments of fermentations process of corn grits were conducted, i.e. spontaneous fermentation (SF) by water soaking of corn grits as a control, fermentation with addition of complete starter culture (CC) from the start of fermentation, and treatment of (CC) with additional amylolytic starter culture (AC) after 16 hours of fermentation. Observations were done on the flour made from corn grits after 0 (unfermented flour, U), 36, 48, and 72 hours of fermentation.
Corn types used in this research were local white maize Anoman 1 and waxy maize Pulut Harapan varieties obtained from the Cereal Crops Research Institute, Maros, Sulawesi, Indonesia. Anoman 1 maize kernel contains high amylose (29.92%), while the waxy maize kernel local Pulut has low amylose content (4.25%) [
Corn was made into grits for a more standardized fermentation process. Kernels of corn were washed with drinking water (corn: water = 1:4 w/v) and drained on a siever. Drained and clean corn kernels were then ground using pin disc mill and sieved to produce grits with diameter of >4 mm. The grits were washed with drinking water (corn grits: water = 1:4 w/v) for 30 minutes and then drained and ready for fermentation.
Microorganisms used for starter culture preparation were amylolytic Penicillium citrinum, Aspergillus niger, Acremonium strictum, and Candida famata, as well as non amylolytic Penicillium chrysogenum, Rhizopus stolonifer, Rhizopus oryzae, Fusarium oxysporum, Kodamaea ohmeri and Candida krusei/incospicua, Lactobacillus plantarum1a, Pediococcus pentosaceus, Lactobacillus brevis1, and Lactobacillus paracasei ssp. paracasei3. The microorganisms used were previously isolated and identified from a spontaneous fermentation of corn grits [
One loop of each mold was streaked onto fresh Potato Dextrose Agar (PDA) slant and then incubated at 30˚C for 5 days. After 5 days molds were harvested by scrapping, suspended in 10 mL sterile water and appropriately diluted for enumeration using hemacytometer. Yeast culture was prepared as above but incubation was carried out at 30˚C for 2 days. Yeast enumeration was also carried out using hemacytometer. Meanwhile Lactic Acid Bacteria (LAB) cultures were prepared by transferring one loop of each LAB growth into de Man Rogosa Sharpe (MRS) Broth for 24 hours at 30˚C using shaking incubator. After 24 hours, the culture was centrifuged aseptically for 15 mins, 3500 rpm at 4˚C and the cell pellets were resuspended in phosphate buffer. The 24 h culture was also enumerated by plating on MRS agar.
Five days old molds and two days old yeast in sterile water as well as 24 hours LAB in phosphate buffer made up the complete starter culture. For amylolytic starter culture, only Penicillium citrinum, Aspergillus niger, Acremonium strictum, and Candida famata were used. Each microorganism was inoculated aseptically into container (15 L) containing of maize grits and drinking water (1:2 w/v) such that each microorganism has an initial load of ca. 106 CFU/mL.
The fermentation studied included spontaneous fermentation, i.e. water soaking of corn grits as a control (SF) and fermentation with added starter cultures. Two treatments of fermentation with added starter were (CC) a complete starter culture containing 15 microbes previously isolated from the spontaneous fermentation added at the beginning of fermentation (0 hours), and (AC) fermentation of (CC) with additional inoculation of amylolytic starter culture at 16 hours of fermentation. Observations were done on flour made from corn grits after 0, 36, 48, and 72 hours fermentation.
Corn flour samples of 3.5 g (14% moisture content) were added to 25 mL of distilled water in an aluminum can. Sample was spinned (160 rpm) at 50˚C for 1 min, and heated to reach 95˚C within 7.5 min, and held at 95˚C for 5 min, and then cooled back to 50˚C within 7.5 min and held at 50˚C for additional 2 min. A typical complete RVA curve obtained is presented in
Parameters derived from the RVA curve were peak viscosity (PV); trough viscosity (TV; also called as hot
viscosity), and final viscosity (FV). The breakdown (BV) and setback (SV) viscosities were calculated from the differences between (PV and TV) and (FV and TV), respectively.
Statistical signifcance of differences between sample means was determined using analysis of variance (ANOVA) followed by Duncan’s Multiple Range Test at 95% confidence level.
Our results showed that pasting properties of corn flour of Anoman 1 and Pulut Harapan varieties were affected by fermentation process. Addition of starter culture for the fermentation showed more complex effect on the pasting properties and was a function of the progress of fermentation reaction.
The pasting profiles (
Treatments | Pasting temperature (˚C) | Peak viscosity (cP) | Trough viscosity (cP) | Breakdown viscosity (cP) | Final viscosity (cP) | Setback viscosity (cP) |
---|---|---|---|---|---|---|
Anoman 1 flour | ||||||
U | 81.5 ± 30.9a | 1276.9 ± 24.4a | 1012.6 ± 27.6a | 264.4 ± 36.4b | 2630.8 ± 0.1c | 1618.3 ± 0.4c |
36SF | 83.4 ± 28.7a | 1451.9 ± 14.8b | 1156.3 ± 29.7b | 295.6 ± 35.7c | 2579.4 ± 0.0b | 1423.1 ± 0.3b |
36CC | 85.0 ± 24.5a | 1290.4 ± 8.8b | 1062.6 ± 23.3b | 227.8 ± 21.7bc | 2575.1 ± 0.0bc | 1512.5 ± 0.3b |
36AC | 82.2 ± 48.8a | 1193.8 ± 22.6a | 1065.8 ± 64.3b | 128.0 ± 62.6a | 2249.0 ± 0.1a | 1183.3 ± 0.5a |
Pulut Harapan flour | ||||||
U | 82.1 ± 25.9a | 1237.7 ± 20.7a | 1090.3 ± 29.5a | 147.4 ± 15.8a | 2017.4 ± 0.7a | 927.1 ± 0.8a |
36SF | 75.6 ± 37.2a | 1680.2 ± 33.3b | 1248.6 ± 24.0b | 431.6 ± 22.3b | 2443.4 ± 0.0bc | 1194.8 ± 0.8a |
36CC | 78.4 ± 23.1a | 1638.4 ± 15.4b | 1251.9 ± 21.1bc | 386.6 ± 18.2b | 2079.4 ± 0.1b | 827.6 ± 0.2a |
36AC | 78.5 ± 9.9a | 1790.0 ± 48.1c | 1439.3 ± 52.7c | 350.8 ± 32.5b | 2537.1 ± 1.0c | 1097.9 ± 2.4a |
Samples means with different superscripts in the same column are significantly different (p < 0.05) by Duncan’s multiple range test.
fermentation both for Anoman I and Pulut Harapan varieties obtained from the RVA curve were evaluated. Unfermented corn flour of Anoman I and Pulut Harapan varieties has peak viscosities (PV) of 1276.9 ± 24.4 cP and 1237.7 ± 20.7 cP, respectively (
Inoculation of a complete starter culture (CC) however reduced the PV of the corn flour of Anoman I variety to 1290.4 ± 8.8 cP. This is due to excessive amylolytic activity leading to more amylose breakdown. Different phenomenon was observed for corn flour of Pulut Harapan variety; which showed that its PV was as high as that of flour obtained from corn grits after 36 hours of spontaneous fermentation (36SF; 1680.2 ± 33.3 cP). Addition of amylolytic culture, however, caused further increase of PV for corn flour of Pulut Harapan variety. This is due to the lower content of amylose (higher content of amylopectin) of corn flour of Pulut Harapan variety. Structurally, the higher amylopectin content of Pulut Harapan corn support granule to be more resistant to amylolytic activity during fermentation. Since the flour has stronger granule integrity, it will swell bigger and has increased peak viscosity.
The viscosity of flour paste decreased after heating process for certain period due the granule breakdown followed by leaching of amylose into the solution [
As we can see from
In general, the FV of unfermented flour of Pulut Harapan (2017.4 ± 0.7 cP) was lower than that of Anoman I (2630.8 ± 0.1 cP). This is associated with its higher amylopectin content of corn of Pulut Harapan. Flour containing higher amylopectin has shown to produce highly gelatinous dispersions when cooked and form soft and runny gels [
The stability of paste during cooling and storage is indicated by SV value; i.e. the differences between FV and TV values. The higher SV value indicates the higher tendency of amylose to retrograde [
For Pulut Harapan corn, unfermented flour has an SV value of 927.1 ± 0.8 cP (
Continued fermentation process of corn grits up to 48 hours of fermentation, resulted in corn flour with pasting profile as presented in
The pasting profile and properties of corn flour of both Anoman 1 and Pulut Harapan obtained after 72 h of fermentation of corn grits was presented at
Treatments | Pasting temperature (˚C) | Peak viscosity (cP) | Trough viscosity (cP) | Breakdown viscosity (cP) | Final viscosity (cP) | Setback viscosity (cP) |
---|---|---|---|---|---|---|
Anoman 1 flour | ||||||
U | 81.5 ± 30.9a | 1276.9 ± 24.4a | 1012.6 ± 27.6a | 264.4 ± 36.4b | 2630.8 ± 0.1c | 1618.3 ± 0.4c |
48SF | 80.8 ± 17.8a | 1432.6 ± 4.9b | 1121.7 ± 23.4b | 310.9 ± 17.1c | 2382.3 ± 0.0b | 1260.6 ± 1.3b |
48CC | 83.8 ± 11.7a | 1489.0 ± 18.0b | 1175.2 ± 29.8b | 313.8 ± 30.9bc | 2645.9 ± 0.0bc | 1470.8 ± 0.3b |
48AC | 81.8 ± 32.5a | 1189.8 ± 13.8a | 1021.3 ± 47.1b | 168.5 ± 36.8a | 2213.0 ± 0.0a | 1191.8 ± 0.4a |
Pulut Harapan flour | ||||||
U | 82.1 ± 25.9a | 1237.7 ± 20.7a | 1090.3 ± 29.5a | 147.4 ± 15.8a | 2017.4 ± 0.7a | 927.1 ± 0.8a |
48SF | 76.9 ± 24.0a | 1901.8 ± 29.6b | 1326.6 ± 48.3b | 575.2 ± 37.3b | 2315.7 ± 0.0bc | 989.1 ± 1.1a |
48CC | 79.7 ± 17.2a | 1825.4 ± 26.4b | 1298.9 ± 38.4bc | 526.5 ± 21.9b | 2234.0 ± 0.1b | 935.1 ± 0.2a |
48AC | 78.1 ± 49.7a | 2134.5 ± 29.7c | 1471.4 ± 62.2b | 663.1 ± 57.1b | 2395.8 ± 0.4c | 924.4 ± 0.2a |
Samples means with different superscripts in the same column are significantly different (p < 0.05) by Duncan’s multiple range test.
Treatments | Pasting temperature (˚C) | Peak viscosity (cP) | Trough viscosity (cP) | Breakdown viscosity (cP) | Final viscosity (cP) | Setback viscosity (cP) |
---|---|---|---|---|---|---|
Anoman 1 flour | ||||||
U | 81.5 ± 30.9a | 1276.9 ± 24.4a | 1012.6 ± 27.6a | 264.4 ± 36.4b | 2630.8 ± 0.1c | 1618.3 ± 0.4c |
72SF | 83.3 ± 14.0a | 1470.5 ± 6.9b | 1113.6 ± 26.9b | 356.9 ± 26.6c | 2459.5 ± 0.0b | 1345.9 ± 0.2b |
72CC | 82.7 ± 10.3a | 1487.1 ± 12.6b | 1179.6 ± 12.5b | 307.4 ± 13.9bc | 2427.9 ± 0.1bc | 1248.3 ± 0.1b |
72AC | 82.0 ± 23.3a | 1251.8 ± 44.0a | 1238.3 ± 43.6b | 176.6 ± 33.7a | 2263.3 ± 2.3a | 1188.1 ± 4.1a |
Pulut Harapan flour | ||||||
U | 82.1 ± 25.9a | 1237.7 ± 20.7a | 1090.3 ± 29.5a | 147.4 ± 15.8a | 2017.4 ± 0.7a | 927.1 ± 0.8a |
72SF | 77.4 ± 23.0a | 1701.0 ± 37.7b | 1214.9 ± 11.2b | 486.1 ± 26.6b | 2091.8 ± 0.1bc | 876.9 ± 0.5a |
72CC | 78.7 ± 19.2a | 2038.0 ± 4.4b | 1333.2 ± 16.3bc | 704.8 ± 9.2b | 2357.3 ± 0.1b | 1024.1 ± 0.2a |
72AC | 77.9 ± 47.8a | 2148.3 ± 40.3c | 1203.1 ± 40.9c | 782.0 ± 21.9b | 2190.4 ± 2.0c | 824.1 ± 4.7a |
Samples means with different superscripts in the same column are significantly different (p < 0.05) by Duncan’s multiple range test.
observed in flour obtained from fermentation process with additional complete culture (72CC). Corn flour of Pulut Harapan obtained from fermentations of corn grits with additional complete culture (72CC) showed further increase in in PV (2038.0 ± 4.4 cP) much higher that that of corn flour obtained from 36 hours of fermentation (36 CC, 1825.4 ± 26.4 cP).
Fermentation process of corn grits affected the pasting properties of the resulting flour, both for Anoman I and Pulut Harapan corn varieties. The differences in the effect of fermentation process on pasting properties were due to the different amylose content of the corn varieties; as observed in Anoman I (high amylose content) and Pulut Harapan (low amlyose content) varieties. The addition of starter culture containing amylolytic microor- ganisms at 16 h of fermentation (AC) resulted in corn flour of Anoman I with lower values of PV, BV, FV, and SV. Meanwhile for corn flour of Pulut Harapan variety, CC fermentation resulted in flour with higher value of PV, BV, FV, and SV. In general, AC fermentation of corn grits could increase the stability of paste for flour containing higher amylose content but decrease the stability of paste for flour containing high amylopectin. Specifically, fermentation with complete starter culture (CC) caused significant increase in the peak viscosity value especially for corn flour of Pulut Harapan. Fermentation for up to 48 h had resulted in corn flour of Pulut Harapan variety having higher value of PV; but it did not affect the tendency to retrograde.
SF = Spontaneous Fermentation
CC = Complete Culture
AC = Amylolytic Culture
RVA = Rapid Visco Analyzer
PV = Peak Viscosity
TV = Trough Viscosity (also called as hot viscosity)
FV = Final Viscosity
BV = Breakdown Viscosity
SV = Setback Viscosity