Assessment of Microbial Load on Fresh-Cut Pineapple in Koforidua (Ghana) Market

Introduction

Fruits and vegetables include different group of plant foods that vary greatly in content of energy and nutrients. These vegetables include pawpaw, pineapple, watermelon, orange, banana and the others [1, 2]. Also, fruits and vegetables supply dietary fiber, and fiber intake which helps to lower incidence of cardiovascular disease and obesity. Fruits and vegetables supply vitamins and minerals to the diet and are sources of phytochemicals that function as antioxidants, phytoestrogens, and anti-inflammatory agents that serve as protective mechanisms for human body [2]. However, Fruits and vegetables are universally recommended as healthy. Slavin and Lloyd (2012) indicated that the Dietary Guidelines for Americans 2010 recommend everyone to consume one-half plate fruits and vegetables.

Although there are challenges in nutrition education intervention programs but they are considered as a good investment in terms of cost. There has been rapid improvement in nutrition education in many countries and majority of interventions has been successful in increasing fruits and vegetables intake [3]. Health professionals are using multiple interventions to deliver information in several ways over time to ensure improvement in fruits and vegetables intake [4]. Although fruit consumption is considered as healthy, it is commonly viewed as a potential risk factor for infection with enteropathogens such as Salmonella and Escherichia coli O157, with recent outbreaks linked to lettuce, spinach and tomatoes [5-7]. The sources of contamination are varied and include the application of organic wastes to farm land as fertilizer, contamination of waters used for irrigation with faecal material, direct contamination by livestock, wild animals and birds and postharvest issues such as worker hygiene [7].

According to a research performed by Edusei et al., vendor use the same water for cleaning so many fruits before peeling it to consumers in Koforidua market. However, this research focused on the assessment of microbial loads on fresh-cut pineapple sold in koforidua Market in Ghana.

Materials and Methods

Microbial evaluation was carried out based on the standard protocol and isolated colonies were identified based on growth in selective media and biochemical tests.25g of the sample pineapple from the each of the three vendors was weighed into a stomacher bag and Buffer peptone water (BPW) of 250g was added and incubated at 37°C for 24 hours. Each sample was serially diluted three times and plated in duplicates.

Enumeration of Yeast and moulds

Yeast and mould were enumerated by using pour plate technique; 1ml of the homogenate sample was pipetted unto a sterile plate Dichloran Rose Bengal Chloramphenicol (DRBC) and swirled clockwise and anticlockwise to provide even distribution of microorganism. The mixture was then allowed to solidify and incubated at 25 ͦ C for five (5) days (48 to 120 hrs) in accordance with ISO 21527-1: (2008). The yeast and mould were enumerated using and the results were recorded.

Enumeration of Escherichia coli

Escherichia coli was enumerated using pour plate technique on a non- selective agar (Tryptic Soya Agar- TSA), this is to resuscitate or revive the weaker or injured microorganism and overlaying Violet Red Bile Agar (VRBLA) with a PH 7 ± 0.2 and incubated at 44°C for 24hours. The colonies that pick the red colors were numerated. Following this, five (5) colonies were randomly sub-cultured into a test tube containing E-coli broth with Durham tube and incubated at 44ºC for 24hours ± 2hours. The test tube containing gases were suspected E-coli.

Enumeration of Coliforms

The total Coliform bacteria were enumerated using pour plate technic on non-selective agar. One ml was pipette and inoculated in the sterile petri dish and the molten TSA was poured and swear clockwise and anticlockwise. This was to resuscitate injured organism and allowed to solidify at a room temperature for 2hours. It was then overlaid with Violet Red Bile Agar (Oxoid CM 107) PH 7 ± 7.2 and incubated at 37ºC for 24hours. After 24hours, the plates with the colonies that pick the violet red colour were counted as a suspected Coliform. This was confirmed by sub-culturing five (5) different colonies in durham tubes containing 5ml Brilliant Green Bile Broth (BGBB) (Oxiod CM 317) with a PH 7.4 ± 0.2 and incubated at 37°C according to NMKL â?? 44 (2004). The tube that produces gas in the durharn tube was confirmed as a Coliform. The reason being that the bacteria ferment the lactose present in the VBRCB to release the gas (hydrogen sulphide gas). The tube with the gas was positive and those without the gas were negative.

Another confirmation test was made for both E. coli and coliform. The samples were prepared as described above. Homogenate or the rinse fluid was prepared using buffered peptone water (BPW). For each selected dilution, 0.1 ml of sample was spread-plated onto brilliance E. coli/coliform agar (Oxoid, Cambridge, UK). The plates were incubated at 37 °C for 24 h, following which, the number of pink (coliform) and purple (presumptive E. coli) colonies were counted. Identification of E. coli was carried out with IMVIC tests.

Enumeration of Salmonella

Salmonella was enumerated by sub culturing 0.1ml of the homogenate sample into a test tube containing 10ml of Rappaport Vassiliadis (RVS) and incubated into a water bath at a temperature of 41.9 °C for 24hours, then vortex and a full loopwas picked and streakedon a Xylose Lysine Deoxycholate Agar (XLD) and incubated at 37°C for 24hours, colonies with yellowish and central black is a suspected salmonella.

Statistical Analysis

The microbial counts were subjected to Analysis of Variance (ANOVA) using the post Hoc Tests. The analyses were completely randomized experiment, the samples taking from the three vendors: Vendor A, B and C were analyzed for salmonella, coliform, Escherichia coli, yeast and moulds.

Results and Discussion

In this research it was confirmed that fresh-cut pineapples sold in Koforidua market are contaminated with Escherichia coli, Coliform, yeast and moulds. The confirmation tests performed for on Escherichia coli and coliform indicated gas production which shows that Escherichia coli and coliform were present. In this research, salmonella did not grow on the plates. This indicated that there were no salmonella present.

                                    Table 1: Descriptive analysis of the microorganisms

The standard deviation of 0.0143032, indicated how the microbial count of the three vendors deviate from the mean of 0.013494 and with their individual deviation of 0.0104625, 0.0172725, and 0.010217 for the vendor (A, B, C) respectively. It further means that there microorganisms present on the fresh-cut pineapples sold on koforidua Market [8]. Gould et al. (2013) indicated that sick persons should not be allowed to process food because it can be a source of bacteria transfer. In most cases, food contamination happens during processing and handling [5]. Similarly, Madden et al. (2018) identified Listeria monocytogenes in food processing industries in Ireland. They confirmed that contamination of food may occur during processing.

              Table 2: Bacteria isolated from the three vendors

*Bacteria counts were not significantly different among the vendors.

There were no significant differences among the vendors. It was possible that the water for washing of the pineapple was dirty, their cutting surfaces were also dirty and they did not wash their hands well before processing. A study case on performed by Edusei et al, 2016 indicated that fresh cut vendors use the same water in washing the fruits over and over again. Table 2 shows that averagely the means of the microbial measure from the three (3) vendors is 1.3×102cfu, which means averagely the bacteria identify from the fresh-cut pineapple they sell is 1.3×102cfu, with their individuals means of 0.009417 for vendor A, 0.020850 for vendor B and 0.010217 for vendor C.

Table 3: Tests Between-Subjects Effects

a. R Squared = .137 (Adjusted R Squared = .084)

According to the Table 3, it is indicated that the significant value for vendors were 0.089 as compare to the alpha value of 0.05. However, we are 95% confidence that bacteriaare present on the fresh-cut pineapple the vendors sell to the general public in Koforidua Market. We fail to reject the null hypothesis (H0) that bacteria exist in fresh¬cut pineapple sold in koforidua market.

The R-squared of 0.137means that about 13.7% of the bacterial tested using the selected vendors were explained by the activities the vendors undertake to process the fresh-cut pineapple to the general public and the remaining 86.3% were the other factors which were not tested for by the researcher. To ensure quality food for consumers, Good Agricultural practices should be put in place, these include clean soil, clean water, hands and clean surfaces. The trucks from the farm to the distribution site can also be a source of contamination. Therefore we need to adapt to good Agricultural practices. This is in agreement to Banzon et al. (2013) that Good Agricultural Practices ensure safety and quality of food and non-food agricultural products [9, 10].

Table 4: Multiple Comparisons test for the three vendors

*. The mean difference is significant at the 0.05 level.

Dependent Variable: microbial

Least Square Difference method (LSD)

The table above show how significant each vendor differs from each other in terms of their location, the environment they operate. Taking their significant level into consideration, it could be found that there were no significant difference between all the three vendors.

Conclusion

Fresh cut fruits sold by vendors on the streets of Koforidua Market are contaminated with Escherichia coli, coliform, yeast and moulds. In conclusion fresh-cut pineapple sold in koforidua market by the vendors is contaminated with microorganisms due to improper handling method.

However, the Food and Drugs authority should organize training sections for the vendors on hygienic methods of processing pineapple to eliminate contamination which may lead to the emerging of food borne illnesses.

References

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