Synergetic effects of Mandillo [Crassocephalum macropappum (Sch. Bip. ex. A. Rich.) S. Moore] during Enset fermentation: chemical nature and efficiency
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Date
2016-04
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Addis Ababa University
Abstract
Enset (Ensete ventricosum (Welw.) Cheesman) is an ornamental plant in Asia, widely distributed
in Africa and cultivated only in some regions of Ethiopia. Enset plant withstands prolonged
period of drought and known for its high yielding potential. Fermentation of Enset produces a
starchy food named Kocho, however, it is not practiced extensively. The principal reasons for
low popularity of Enset are its uncommon sensory attributes among non-Enset consuming
people, short shelf-life, nutrient losses, long fermentation period and lack of awareness. In
Ethiopia, the Shekacho society adds Mandillo (Crassocephalum macropappum (Sch. Bip. ex. A.
Rich.) S. Moore) stem during traditional Enset fermentation without knowing its scientific
significance to the fermentation processes. Thus, the present study was initiated with the main
purposes of investigating the indigenous knowledge of Shekacho society in Enset cultivation,
Kocho consumptions, bioactive components of Mandillo parts and to determine its effects in
Enset fermentation processes. The study was conducted using standard methods. To evaluate the
indigenous knowledge of Shekacho society, analytical data were collected using semi-closed
questionnaire, field observations, interviews and discussion with key informants with local
annotations review. Enset plant physical structures were assessed. Phytochemical composition of
Mandillo was evaluated. Its DNA damage protective and antioxidant activities were analyzed.
Antimicrobial activity of Mandillo was tested against standard bacterial and yeast strains.
Cytototoxicity of Mandillo was also evaluated. Fermentation process was carried out from 0-90
days. The pH value, titratable acidity, lactic acid and acetic acid contents were measured.
Microbial counts were made on their respective agar media. Lactic acid bacteria (LAB) and yeast
isolates were identified using morphological, biochemical and molecular techniques. Proximate
composition, mineral contents, phytic acid, tannin, water holding capacity, and sensory attributes
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of Kocho were evaluated and the main findings are described as follows. The descriptive analysis
of the data and the corresponding results indicated the existence of a high degree of consistency
among the respondents with regard to Enset histories, fermentation processes, productivity,
shelf-life of Kocho and food preparation. About 115 Enset cultivars were identified.
Phytochemical analysis of Mandillo showed the presence of saponins, tannins, anthraquinones,
steroids, terpenoids and flavonoids. Total phenolic and flavonoid contents of the aerial part
calculated as 101.48 mg GAE (Gallic acid equivalent)/g and 293.25 mg QE (Quercetin
equivalent)/g, respectively. Mandillo showed strong 2, 2-diphenyl-1-picryl hydrazyl (DPPH)
scavenging potential with IC50 ≤ 50 μg/mL. The stem of Mandillo showed promising protective
activity against oxidative DNA damage. The minimum inhibitory concentration of stem against
E. coli KCTC 1682 and Candida utilizes KCCM 11355 was ≥ 15.62 μg/mL. The final pH of
Kocho fermented with starter culture but no Mandillo (Koki) and with Mandillo (Kom)
decreased to 4.49 and 4.10; respectively, which are significantly different and didn’t allow the
growth of spoilers in Kom. Titratable acidity, lactic acid and acetic acid contents of Kom
increased by 64.34%, 103.90% and 40.04%, respectively when compared to Koki. Koki and
Kom samples had LAB counts of 1.16×107 and 2.83×108 CFU/g, respectively, on the day 37.
Treatments with Mandillo stem significantly (p < 0.05) lowered counts of aerobic mesophilic
bacteria, aerobic spore formers and coliforms. Staphylococci were below detectable level. The
16S rRNA gene sequences analysis and phylogenetic tree reconstruction identified LAB species
as Lactobacillus plantarum (69.37%), Leuconostoc mesenteroides (9.91%), Lac. paracasei
(9.01%), Lac. brevis (3.60%) and other rare species. Lac. paracasei and Lac. brevis were
dominantly found in Kom during the final days of fermentation. An 18S rRNA gene sequences
evaluation identified yeast isolates as Candida boidinii (30%), Wickerhamomyces sp. ES22S03
(16%), Pichia fermentans (16%), Williopsis sp. (10%) as dominate species and others minor
strains. Kocho composition analysis showed significant (p < 0.05) differences between Koki and
Kom in moisture contents (8.34 to 8.80%) and (9.14 to 7.95%), fiber (7.92 to 5.56%) and (6.25
to 3.96%), protein (3.24 to 3.68%) and (3.59 to 3.95), phytic acid (5.83 to 4.11 mg/g) and (4.95
to 4.33 mg/g), water holding capacity (8.55% and 6.37%); respectively. Mineral contents of Koki
and Kom also calculated as Ca (9.84 mg/100 g and 10.08 mg/100 g), Fe (2.12 mg/100 g and 2.08
mg/100 g), Zn (1.99 mg/100 g and 1.77 mg/100 g) and Cu (0.12 mg/100 g and 0.16 mg/100 g);
respectively. Sensory evaluation revealed overall acceptability values of 73.27% (Koki) and
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97.20% (Kom). Cytotoxicity evaluation of Mandillo stem against Raw Cells 264.7 showed no
toxicity at ≤ 4 μg/mL. From the results of the descriptive analysis of the data and the
corresponding results suggested by the respondents, it is understood that Enset is very important
for food security and environmental protection. Phytochemical contents and activities of
Mandillo revealed consistency with the starter culture role played by the addition of the stem part
of the plant. The effect of adding Mandillo during Enset fermentation showed significant
differences in all of the measured Kocho quality parameters, food composition, microbial
dynamics and diversities and sensory attributes of experimental Kocho product compared to the
control sample. In general, improvements of the basic components of Kocho dough are
responsible for the enhancement of its shelf-life, safety and sensory attributes of the food as a
result of good fermentation processes. In the light of the current finding, extensive investigation
are required to qualify Mandillo as food preservative and shelf-life enhancer for its application
in food sectors.
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Keywords
Food and Nutrition Science