Synergistic Bio-preservative Effects of Vernonia Amygdalina Leaves and Sacog...

Onwuakor Chijioke .E, Ukaegbu-Obi K.M

  Open Access OPEN ACCESS  Peer Reviewed PEER-REVIEWED

Synergistic Bio-preservative Effects of Vernonia Amygdalina Leaves and Sacoglottis Gabonensis Stem Bark on Palm Wine from Elaeis Guineensis and Raphia Hookeri from Uturu, Nigeria

Onwuakor Chijioke .E1,, Ukaegbu-Obi K.M1

1Department of Microbiology, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria

Abstract

The synergistic bio-preservative effects of leaves and stem bark of Vernonia amygdalina and Sacoglottis gabonensis respectively on two (2) palm wine types namely, Elaeis guineensis and Raphia hookeri from Uturu-Nigeria was evaluated. The microbiological and biochemical changes of the palm wine brands were determined. R. hookeri brands were found to support more heterotrophic and coliform populations than the E. guineensis, while the later contained more yeast species. Identification of isolated species revealed the presence of Bacillus sp., Micrococcus sp., Lactobacillus sp., Brevibacterium sp. and Saccharomyces sp. from E. guineensis and R. hookeri. Moreso, heterotrophic counts and pH were observed to decrease as the fermentation time progressed. The combination of both V. amygdalina and S. gabonensis as preservatives lowered the bacterial and fungal load compared to the control and individual plant preservatives and reduced the rate of CO2 emission as well as keeping the pH fairly constant.

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Cite this article:

  • .E, Onwuakor Chijioke, and Ukaegbu-Obi K.M. "Synergistic Bio-preservative Effects of Vernonia Amygdalina Leaves and Sacoglottis Gabonensis Stem Bark on Palm Wine from Elaeis Guineensis and Raphia Hookeri from Uturu, Nigeria." American Journal of Microbiological Research 2.4 (2014): 113-117.
  • .E, O. C. , & K.M, U. (2014). Synergistic Bio-preservative Effects of Vernonia Amygdalina Leaves and Sacoglottis Gabonensis Stem Bark on Palm Wine from Elaeis Guineensis and Raphia Hookeri from Uturu, Nigeria. American Journal of Microbiological Research, 2(4), 113-117.
  • .E, Onwuakor Chijioke, and Ukaegbu-Obi K.M. "Synergistic Bio-preservative Effects of Vernonia Amygdalina Leaves and Sacoglottis Gabonensis Stem Bark on Palm Wine from Elaeis Guineensis and Raphia Hookeri from Uturu, Nigeria." American Journal of Microbiological Research 2, no. 4 (2014): 113-117.

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1. Introduction

Palm wine is the fermented sap of various palm trees especially Palmyra, silver date palm and coconut palms. Palm wine can be obtained from the young inflorescence either male (or) female ones. Palm wine is an alcoholic beverage that is made by fermenting the sugary sap from various palm plants. It is collected by tapping the top of the trunk by felling the palm tree and boring a hole into the trunk. It is a cloudy whitish beverage with a sweet alcoholic taste and a very short shelf life of only one day. The wine is consumed in a variety of flavors, varying from sweet-unfermented to sour-fermented and vinegary. There are many types of the palm wine products and is particularly common in parts of Africa, South India and Mexico. Some of the local names for the product include Emu and Ogogoro in Nigeria and Nsafufuo in Ghana [1].

The wine is an excellent substrate for microbial growth and fermentation starts soon after the sap is collected and within an hour or two becomes reasonably high in alcohol (up to 4%); if allowed to continue to ferment for more than a day, it starts turning into vinegar [1].

Palm wine is consumed throughout the tropics and appears as a whitish liquid produced by natural fermentation of the sap of Elaeis guineensis and Raphia hookeri [2]. The unfermented sap is a clean, sweet, colourless syrup containing about 10 - 12% sugar, which is mainly sucrose [3]. Upon fermentation by the natural microbial flora, the sugar level decreases rapidly as it is converted to alcohol and other products [4] whereas, the sap becomes milky-white due to the increased microbial suspension resulting from the prolific growth of the fermenting organisms [5].

Vernonia amygdalina (Del.) commonly called bitter leaf is the most widely cultivated species of the genus Vernonia which has about 1,000 species of shrubs [6]. It belongs to the family Astaraceae. It is popular in most West African countries including Nigeria, Cameroon, Gabon and Congo Democratic Republic.

Sacoglottis gabonensis is a tropical rainforest tree found in the tropical rainforest region of Africa and America. It belongs to the family Humiriaceae. In certain rural communities of Nigeria especially Abia, Akwa-Ibom, Rivers, Delta, Edo and Imo State, the stem bark of this tree is commonly used as an additive to palm wine [7].

This study is therefore aimed at ascertaining microbial and biochemical changes associated with non-preserved and the combined bio-preservative effect of V. amygdalina and S. gabonensis on the two brands of palm wine.

2. Materials and Methods

2.1. Materials
2.1.1. Sample Collection

Fresh palm wine samples from oil palm tree (E. guineensis) and Raphia palm (R. hookeri) was separately collected from traditional palm wine collectors from Uturu, Abia State, Nigeria. The freshly tapped samples were collected using a total of 10 pre-sterilized 100 ml capacity bottles with screw caps. The perforated screw caps were plugged with sterile non-absorbent cotton wool. Each of the two different palm wine types were collected in 5, 100 ml bottles. The samples were transported to the laboratory in a cooler equipped with packs of freezing mixture of salt and ice-block for analysis within 1 h of collection; this was to help reduce the fermentation rate.


2.1.2. Plant Materials

Leaves and stem barks of Vernonia amygdalina and Sacoglottis gabonensis respectively were collected from National Research Institute Umudike, Abia State, Nigeria. The plant materials were authenticated by the Department of Plant Science, Abia State University Uturu, Nigeria. The plant materials were and washed with sterilized water and then with absolute ethanol and shade dried (25C ± 2 for 14 days). The dried leaves and stem bark were then ground to a fine powder in a mechanical blender and mixed together.

2.2. Methods
2.2.1. Treatments

A total of 8 bottles, 4 for each of the two palm wine samples, were labeled thus:

Control (C): Sample without preservative

T0: Sample with only Vernonia amygdalina

T1: Sample with only Sacoglottis gabonensis

T2: Sample with both Plant materials.


2.2.2. Preservation Treatments

Three – 60 ml sample of each Raphia and Oil Palm wine were treated with a total of 3 types of preservatives namely, Vernonia amygdalina only (T0), Saccoglottis gabonensis only (T1), combination of Saccoglottis gabonensis and Vernonia amygdalina (T2); whereas, the one sample bottle was left without any form of preservative (C) as control. The treatment was carried out by adding 10 mg of each powdered traditional preservative to the sterile sample bottles, but 5 mg each of both plant materials for T2. Thereafter, 60 ml of fresh palm wine sap were added, gently shaken to mix and allowed to stand in a laboratory glass cabin sterilized using 2.5% acid alcohol.


2.2.3. Microbial Isolation

1ml aliquots of each palm wine sample were taken aseptically at 24, 48, 72, 96 and 120 hours of fermentation and were serially diluted 10-fold in 0.1% (w/v) peptone. 1ml dilutions were plated out in duplicates using spread plate method [8], on tryptone soy agar (Oxoid) for total heterotrophic bacterial count, MacConkey agar (Oxoid) for the total coliform count and Sabouraud dextrose agar (Oxoid) containing 0.05 mg/ml chloramphenicol for yeast count as described by [9]. The inoculated plates were incubated aseptically at 30C for 24 h for bacteria and 24–48 h for the yeast. Acceptable plated were those that contained between 30-300 cfu/ml. They were stored on agar slants at 40C for characterization.


2.2.4. Characterization of Isolates

The Isolates were grouped according to their colonial morphology and cell characteristics. The colonies were counted and re-isolated in pure culture using the medium on which they had grown as described by [10]. Isolates were thereafter subjected to biochemical tests as described by [11]. The probable identities of the isolates were determined as recommended by [12].


2.2.5. Chemical Analysis

The method described by [13] was adopted to determine the rate of CO2 evolution and pH of the sample.


2.2.6. Data Analysis

The experimental results were expressed as mean ± standard error of mean (SEM) of three replicates. The results were processed using Microsoft Excel 2007 and Origin 6.0.

3. Results

The microbiological assays revealed that more total heterotrophic bacteria and coliform counts were obtained from palm wine from R. hookeri than E. guineenesis while the later had more yeast counts than the former (Figure 3 to Figure 8). The mean occurrence of the bacterial genera and yeast revealed a sharp increase from 0–24 h for the total heterotrophic bacteria for both samples and gradually reduced as fermentation time increased in both test and control samples, while coliform counts gradually increased up to 72 h and started reducing in both samples. Yeast population showed a steady increase from 24 h of fermentation to the 48 h. Thereafter, a sharp progressive decrease was observed from 72 h.

Figure 3. Total Heterotrophic counts of isolates in palm wine from Elaeis guineensis
Figure 4. Total Heterotrophic counts of isolates in palm wine from Raphia hookeri
Figure 5. Total Coliform counts of isolates in palm wine from Elaeis guineensis
Figure 6. Total Coliform counts of isolates in palm wine from Raphia hookeri
Figure 7. Total Yeast counts of isolates in palm wine from Elaeis guineensis
Figure 8. Total Yeast counts of isolates in palm wine from Raphia hookeri
Figure 9. Percentage CO2 released from palm wine harvested from Elaeis guineensis
Figure 10. Percentage CO2 released from palm wine harvested from Raphia hookeri

Generally, in all samples of E. guineensis and R. hookeri, low heterotrophic, coliform and yeast counts were observed to be far lower in the samples with both V. amygdalina and S. gabonensis compared to individual plants when used as preservatives.

The percentage carbon (iv) oxide (CO2) evolved during the different fermentation times are shown in Figure 9 and Figure 100 for palm wine from E. Guineensis and R. hookeri respectively.

The two types of palm wine samples showed considerable decrease in pH values as fermentation time increased in all samples except for the samples containing both V. amygdalina and S. gabonensis as shown in Table 1 and Table 2.

Table 1. Effect of Single and Combined Plant Preservatives on pH of Palm Wine from E. guineensis

Table 2. Effect of Single and Combined Plant Preservatives on pH of Palm Wine from R. hookeri

Isolation and identification test revealed the presence of more bacteria in the palm wine from R. hookeri than in E. guineensis palm wine. Isolates from E. guineensis include Saccharomyces sp., Lactobacillus sp., Bacillus sp. and Brevibacterium sp. Isolates from R. hookeri included all the isolates from E. guineensis except for Micrococcus sp. The survival rates of these isolates were affected by increase in fermentation time (Table 3).

Table 3. Effects of Fermentation Time (Hrs) on the Survival Rate of Fungal and Bacterial species from Palm Wine

4. Discussion

The total heterotrophic bacterial counts were relatively low in palm wine samples treated with V. amygdalina and S. gabonensis compared to those preserved with only one plant preservative and sample with no preservative at all. Peak heterotrophic bacterial counts were obtained after 24 hours fermentation except for the sample with no form of preservative. This agrees with [14] that observed higher bacterial counts after 24 hours fermentation of palm wine.

A gradual loss of bacterial and fungal viability was noticed as fermentation time increased from 48 hours to 120 hours. Five probable microbial isolates were identified; they include Bacillus sp., Micrococcus sp., Lactobacillus sp., Brevibacterium sp. and Saccharomyces sp. The isolation and identification of these microbial species from fermenting palm wine is in line with the work of [15] that shows the presence of different microbial flora of exposed fermenting palm wine.

The isolation of Micrococcus sp. from fermenting palm wine possess health implications which might have been due to the exposure of freshly tapped wine; which supports the research done by [16], that showed various forms of pathogenic bacteria associated with exposed palm wine. The frequent Gastro-intestinal problems associated with drinking palm wine well over 24 hours could be attributed to the presence of pathogenic bacteria in palm wine.

The slow reduction in bacterial and fungal isolates from palm wine over the fermenting period could be attributed to the gradual depletion of fermenting sugar, production of organic acids and consequent reduction of pH.

The gradual reduction in viability of microbial isolates in palm wine preserved with plant materials could also be attributed to the presence of bioactive components present in the V. amygdalina and S. gabonensis. This supports the work of [17], which showed antibacterial effects of medicinal plants against pathogens.

However, [18] reported that preservation of palm wine could be achieved through inactivation of microorganisms at about 15 hours after tapping. The Combination of such methods with subsequent preservation using plant preservatives such as V. amygdalina and S. gabonensis could however extends the shelf life of palm wine even more.

5. Conclusion

This study therefore showed that combined use of V. amygdalina leaves and S. gabonensis stem bark may have usefulness in extending the shelf life of the two types of palm wine by offering cheaper preservative means of extending the shelf-life of locally tapped palm wine. Further developments as a possible avenue to strengthen the shelf life extension methods employed in palm wine preservation without affecting the taste and acceptability could be achieved, thus contributing to the search for low cost preservative methods for palm wine storage.

Conflict of Interest

Authors have declared that no competing interests exist.

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