Fruit is often recommended to prevent and reduce the risk of chronic degenerative diseases, cardiovascular diseases and diabetes (Benton and Young, 2019). They remain an important source of minerals, vitamins, phytoconstituents and phenolic compounds (Asandé et al., 2020). Thus, many fruits contain phenolic amino acids, organic acids such as tartronic acid (Sun et al., 2018), minerals such as Ca, K, Mg, Fe and Se (Doharey et al., 2021) and vitamins such as vitamin C, riboflavin and niacin (Zaini et al., 2011). Several medicinal properties such as anxiolytic, anticonvulsant, antidepressant, anti-inflammatory, analgesic and anti-asthmatic effects have been associated with fruits (Tiwari et al., 2013). For a healthy diet and better overall health, the Food and Agriculture Organization of the United Nations recommends a daily fruits consumption of at least 400 g (FAO, 2020). However, the adoption of this recommendation, especially in most developing countries, is very difficult. Indeed, in these low-income countries the diet is essentially based on cereals and tubers (FAO, 2020).

In Benin, the abundant consumption of fresh fruit by the population faces several difficulties, namely: high prices, inadequate preservation technologies, high post-harvest losses due to poor sales, and the fragility and seasonality of fruit. Faced with this situation, fruit transformation into other by-products is essential. The processing of fruit into fruit juice is widespread in Benin. Indeed, fruit juice is a nutritious drink that not only contains vitamins, minerals, proteins and protective antioxidants, but also provides an additional source of water (Heyman and Abrams, 2017).

Noumavo et al. (2022) showed that the fruit juice production sector is growing rapidly in southern Benin. It creates huge employment and generates significant income for the actors in the sector. However, the production and conservation conditions of these juices do not guarantee the required food safety. Indeed, the production methods of these juices are often artisanal, under unsatisfactory hygienic conditions. The ingestion of food or drink contaminated by certain infectious or toxigenic agents is a public health problem throughout the world. Foodborne diseases affect one in ten people every year and 420,000 people die from them (Petruzzi et al., 2017). These foodborne infectious diseases can also have a significant economic impact because of treatment cost.

This study aims to identify and evaluate the microbiological quality of the different fruit juices produced in southern Benin.

Geographical area

The present study was carried out in southern Benin, particularly in the municipalities of Abomey-Calavi (6?26'9112 "N; 2?21'3396 "E) and Cotonou (6?21'9216 "N; 2?25'0998 "E). These two municipalities contain the majority of fruit juice producing enterprises in southern Benin. Indeed, they are very close to Allada department, an area of large fruit production, particularly pineapple (Ananas cosmosus) in Benin.

Diversity evaluation of fruit juices

This study was conducted from November 2020 to February 2021. Fifty (50) fruit juice enterprises previously identified by Noumavo et al. (2022) were involved in the present study. These included semi-industrial (05) and artisanal (45) enterprises. Within the artisanal enterprises (A), several sub-groups can be distinguished: A1 enterprise have no mechanized equipment except for a manual capper; A2 enterprise have an extractor and/or grinder, all stainless steel or not, and then a manual capper; A3 enterprise have an extractor and/or grinder and a press, a cooker, all stainless steel, and then a manual capper; and finally A4 companies have a cooker, an extractor, a press, a pasteurizer all stainless steel, and then a manual capper. Different fruit juices census was carried out by a semi-structured survey coupled with direct observations.

Microbiological analysis of fruit juices

The microbiological investigation was carried out only on mono-fruity pineapple juice at the Laboratory of Microbiology and Food Technology (University of Abomey-Calavi, Benin). A total of 100 juice samples were collected (two samples per enterprise). The sampling, transport and storage of the samples were carried out under technical conditions that prevented any modification of their microbial flora. The preparation of decimal dilutions was done under aseptic conditions according to Speck (1976) method. Microorganism’s enumeration was performed according to the method used by Ohin et al. (2018). Thus, Total Mesophilic Aerobic Microorganisms were counted on Plate Count Agar (Oxoid, England) after incubation at 30°C for 72 h. Total Coliforms and Faecal Coliforms were isolated on Violet Red Bile Lactose agar (Liofilchem Diagnostici, Italy) after incubation at 30 and 44°C, respectively for 24 h. Lactic acid bacteria were counted on MRS (de Man, Rogosa and Sharpe) agar after incubation at 37°C for 72 h. Tryptone Sulfite Neomycin agar (Biokar Diagnostics, France) was used to enumerate anaerobic sulfite-reducing bacteria (44°C for 24 h). Yeasts and molds were enumerated on Sabouraud agar (Biokar Diagnostics, France) supplemented with Chloramphenicol (25°C for 5 days). Finally, Staphylococcus aureus were isolated on Baird Parker agar (Biokar Diagnostics, France) supplemented with egg yolk and potassium tellurite after incubation at 37°C for 48 h.

Data management and analysis

Data from the survey forms and microbiological analysis were encoded using the Microsoft Excel 2013 spreadsheet for descriptive statistics (mean, proportion and standard deviation). The R.4.0.0 software was used to carry out the Analysis of Variance (probability level of 5%) and the Student-Newman-Keuls test.

The presence of coliforms is on one hand an indicator of fecal contamination, by germs that are not directly pathogenic, but whose presence suggests the existence of pathogenic germs for human beings. With the exception of the genus Klebsiella and a few others, fecal coliforms are made up of nearly 80% Escherichia coli. Three major groups of E. coli are involved in diarrheal syndromes in humans and young children, especially in developing countries. These are enterotoxigenic E. coli, the cause of traveler's diarrhea and childhood diarrhea;

enteropathogenic E. coli, agent of infantile gastroenteritis; and finally enterohaemorrhagic E. coli, agent of hemorrhagic colitis. E. coli serotypes O157 and O157: H7 are enterohemorrhagic E. coli, agents of serious food poisoning linked to the consumption of meat, unpasteurized apple juice, etc. The second serotype is also called verotoxigenic E. coli (VTEC) (Delarras, 2008).

A single germ indicator of mucocutaneous contamination was sought in pineapple juice. This is S. aureus known to be common to the bacterial flora of human skin (Alabi et al., 2021), whose microbial load in this study varied markedly (p < 0.001) between the juices of the different types of business. Contrary to the general trend observed with the other germs sought, juices from semi-industrial SI companies are highly contaminated with S. aureus. The S. aureus microbial load of these juices is at least 8 times higher than that of juices from other types of companies. This result remains a priori paradoxical because within semi-industrial companies, manual activities are quite limited compared to craft companies. However, it should be noted that one of the 5 SI companies investigated does not peel the pineapple fruits before grinding. Indeed, often not well-washed pineapple fruits are directly crushed with the skin using a crusher. When we refer to the method of transporting pineapple fruits from the fields or supply markets to the processing units and to the method of receiving and storing pineapple fruits, it is easy to see that the bare hand is heavily used. The fruits are even in many cases received on the ground. It should also be noted that within these companies, the washing of the packaging bottles, the filling and the capping are done by hand in conditions that are not often hygienic. To all this is added the defects of pasteurization often noted within companies in general. All these observations, although not exhaustive, could explain this high load of S. aureus in juices from SI enterprises.

This presence of S. aureus in the pineapple juice analyzed is very worrying. Indeed, food poisoning due to S. aureus does not result primarily from the ingestion of the bacterium itself, but rather from the toxins preformed in the contaminated food (Moloi et al., 2021). Staphylococcal food poisoning is mainly caused by a particular group of toxins called enterotoxins (Chebana et al., 2021). These enterotoxins are heat stable, highly toxic and persist in food even after adequate cooking (Ghalehnoo, 2018). Twenty-two (22) Staphylococcal Enterotoxins (ES) have been described and designated by the letters ESA to ESV in the chronological order of their discovery (Hennekinne et al., 2010). Staphylococcal Food Poisoning (SFP) is characterized by a sudden onset of symptoms (1 to 6 h after ingestion), with vomiting, abdominal pain and stomach cramps (Fetsch et al., 2014). SFP can lead to hospitalizations, especially among young, old, pregnant and immunocompromised (Murray, 2005).

This study of fruit juices diversity and quality in southern Benin provides important data for restructuring the sector. This study revealed a strong diversity of mono-fruity and poly-fruity juices. Mono-fruity juice of pineapple is produced by almost all the enterprises. Pineapple is incorporated in majority of poly-fruity juices. From the microbiological point of view, a strong variation of the microbial load was noticed from one enterprises to another. With the exception of a few enterprises, about 18% of pineapple juices are microbiologically non-compliant. These pineapple juices contain mycotoxigenic yeasts and moulds, lactic acid bacteria, thermotolerant coliforms and S. aureus. The consumption of these juices poses a real public health problem, as it exposes consumers to the severe food poisoning risks.

The authors have not declared any conflict of interests.

The authors thank the fruit juice enterprises involved in this study and researchers of Laboratory of Microbiology and Food Technology (Abomey-Calavi University) for their assistance.