**3. Findings and discussion**

#### **3.1 Microbiology and pathology**

#### *3.1.1 Bacteria salmonella*

It is a gram-negative bacterium that is common in nature and can survive in it for a long time. This bacterium is found in all types of animals and is one of the most important causes of diarrhea in humans. Food, at any stage of the productionto-consumption chain, can be contaminated with this bacterium through indirect contact with human or animal feces. This pathogen can survive in or on food for

#### *Safety of Food throughout the Supply Chain DOI: http://dx.doi.org/10.5772/intechopen.105670*

several months. Even frost cannot kill it [2]. Compared to other bacteria, it can grow in a variety of conditions. This bacterium can multiply at a temperature of 7–45°C, and the higher the temperature, the more it multiplies. The ideal temperature for the multiplication of these bacteria is 37°C. Only at temperatures above 60°C does the bacterium begin to die. Multiplication of this bacterium is also possible at pH 4–5 [2].

Humans are infected with Salmonella bacteria by eating contaminated food. But the infection can also occur through direct contact with a sick animal or human. The pathogenic dose for an adult is 104–106 Salmonella bacteria [6]. Depending on the amount of fat in the food and the immune status, even doses of less than 100 Salmonella bacteria can cause disease. After infection and the average incubation time, the first symptoms of the disease are observed after 12–36 h [6]. This bacterium causes diarrhea with abdominal pain, nausea, vomiting, and fever. In some cases, especially in vulnerable people, this bacterium causes severe illness and even death [6]. According to the Robert Koch Institute in Germany (RKI), Salmonella infected 17 people by eating melon, of which eight were hospitalized [6]. Vulnerable people include children under the age of five whose immune system has not yet been developed, adults, and those who already have a disease and are under treatment [2].

#### *3.1.2 Listeria monocytogenes*

It is a gram-positive bacterium and is a very important representative of genes Listeria. This bacterium is very common in nature and is found in soil, surface water, sewage, plants, and the digestive system of animals. This bacterium can contaminate food along with the production chain to the consumption of food, for example, during milking, butchery, vegetable or fruit collection; or cause contamination during food processing. Foods that are eaten raw have a higher risk of infection because they do not undergo any germicidal process after processing [7]. Listeria lives and multiplies in high temperatures and pH, and in a salty environment, and is a bacterium that is resilient and adapts to a variety of environmental conditions. It can multiply at 4–45°C and at pH 4.3–9. In addition, it can multiply at a salt concentration of 13% [7]. The ideal temperature for the multiplication of this bacterium is 30–37°C in neutral and slightly humid conditions, where the salt concentration is 0.5% [8].

The bacterium is transmitted to humans primarily by eating contaminated food. The dose of trauma depends on the condition of the immunity and the health of the person. According to European Union (EC) laws, ready-to-eat food is safe if the bacterial dose per gram is less than 100 calories (CFU) [6]. A healthy person does not develop a serious illness after an indication, but either develops cold symptoms or has indigestion. Unless people have a weak immune system, they can develop severe illness after several weeks of incubating the bacteria in their bodies. The bacterium causes blood poisoning, encephalitis, or meningitis, and the mortality rate from this bacterium is low. In pregnant women, it can lead to failure or premature birth and can cause irreversible disorders in infants. In Germany, 337 cases of Listeria's disease have been reported [9]. In addition to infants, people older than 60, especially men, developed leukemia. In 2011, 147 people in the United States became infected with Listeria, and 33 of them died [10]. In this country, Listeria bacteria was found in many samples of melons. The US Food and Drug Administration (FDA) has concluded that the disease is present in the melon peel and enters the inside of the fruit through the skin and is then transmitted to humans through eating the flesh [10]. According to European Union (EC) regulations, the concentration of Listeria in prepared foods should not exceed 100 colonies per gram of food.

#### *3.1.3 Enterohemorrhagic Escherichia coli*

A gram-negative anaerobic bacterium, abbreviated as E. coli, is capable of producing the poison ciguatoxins that cause bloody diarrhea in humans. The bacterium E. coli O157: H7 causes many diseases worldwide. This bacterium is present in the digestive system of ruminants, such as cattle, sheep, goats, and deer, and is transmitted to the environment through animal feces. This bacterium was resistant to drought, frost, and acidity, which means that it can survive in soil, water, and feces for several months [2, 10].

Food is contaminated with this bacterium at any stage of the production-to-consumption chain through direct or indirect contact with the feces of an infected animal or human. This bacterium multiplies at a temperature of 8–45°C and increases with increasing temperature. The ideal temperature for the multiplication of these bacteria is 37°C. Observation of E. coli O157: H7 in 0.5, 1, and 1.5% of organic acid (HCl) indicates that this bacterium also tolerates acidic conditions [2, 10]. In one experiment, using synthetic gastric extract, E. coli O157: H7 was observed to survive at pH 1.5 and it was found that this bacterium is also resistant to strong acidity [2].

The bacterium can also be spread through direct contact or by eating contaminated food by humans. The infectious dose of this bacterium is very low, that is, 100 of them cause disease. The incubation period is 2–10 days and averages 3–4 days. This bacterium causes watery diarrhea. In some cases, it causes swelling of the intestines and causes seizures and stomach pain, producing bloody stools, and in some cases, fever. Except after the disease is in the early stages, it does not show any symptoms [10]. In young children, the bacterium causes uremic hemolytic syndrome (HUS). In some cases, kidney failure, anemia, and thrombocytopenia can occur. These severe symptoms occur in 5–10% of patients. In the acute stage, the mortality rate due to this disease factor reaches 2% [2].

#### **3.2 Pathogenic contamination**

#### *3.2.1 Melon consumption*

Melons, like many other fruits and vegetables, can be produced both in the greenhouse and outdoors. After collection, it is either packaged directly on the farm or cooled before packaging. In arid regions (such as Afghanistan) packaging on the farm is common [11]. Melons are either sold whole or sliced, and in large stores, they are sliced and wrapped in plastic, which is sometimes mixed with other fruits. In Germany, the cooling of melon slices is prohibited [11].

According to estimates by the European Food Safety Authority [12], about 7% of European citizens consume melons [12]. It has also been observed that melons are consumed by all age groups, including children and the elderly, due to their deliciousness [13].

#### *3.2.2 Contamination of melon fruits*

Melons are grown on the ground. They need warm, sunny weather and moist soil. Due to the size and weight of its fruits, the fruits are in contact with the ground and are easily contaminated with pathogens, either through contaminated soil or water [14]. Studies in Mexico and the United States show that irrigation is a major cause of contamination [14]. Another study, conducted in Texas, USA, found that irrigation

*Safety of Food throughout the Supply Chain DOI: http://dx.doi.org/10.5772/intechopen.105670*

water was contaminated with 9.4% Salmonella bacteria [15]. Insects are also carriers of pathogens [16]. A study by Lopez-Velasco et al. [16] found that Salmonella could also enter plants through roots; they concluded that the possibility of root infection was not high and skin contamination was the main cause.

The fruit part that is in contact with the ground is a special area for contamination with bacteria and fungi. To reduce this contamination, the ground is covered with plastic, or fruits are placed in plastic bags. Another way to reduce contamination is to roll (turn over) the fruit repeatedly. This is done by the hands and if the hands are not clean, it will cause more contamination [17].

Contamination also occurs during collection and transfer, for example, by infected people. After harvesting, the fruits are cooled by air or water, in both cases, there is a possibility of contamination and spread of contamination [18]. Clean melons are also contaminated, especially when washed in the basin [18]. In a study by Duffy et al. [19], which compared washed and unwashed melons, it was found that washed melons were contaminated with Salmonella, because contaminated surfaces, as well as contaminated fruits, caused contamination of other fruits. Similarly, the Salmonella bacterium was observed in samples taken from cold storage [20].

To keep the fruit cool during transfer, ice is placed around it, which is usually melted and this causes the contamination of clean fruits [19]. All stages of melon production require human labor. The germs survive on the skin of the melon [17]. In particular, coarse skin is a good place to protect germs from washing and disinfection [18]. The larger the skin of the melon, the more germs it contains (**Figure 1**) [2].

#### *3.2.3 Presence of pathogens in melon*

In one observation, out of a total of 366 cantaloupe melons, 16 were contaminated with pathogenic microbes. Salmonella was observed in eight specimens, and Shigella in four specimens, while E. coli was not observed in this specimen [10]. In

**Figure 1.** *Showing the food supply chain.*

another study by the Austrian Institute of Technology [1], it was observed that the presence of Salmonella in melons is different [1]. In Mexico, 12 out of 55 samples were infected with Salmonella. In Nigeria, three out of every 50 melons were infected with Salmonella bacteria. In addition to Salmonella, other microbes, such as Staphylococcus aureus, Enterobacter aerogenes, and Klebsiella pneumoniae, were also observed [4]. In 2000, Castillo et al. [5] collected 950 samples of melons from Texas and 300 samples from Mexico; 0.5% of the samples were from Texas and 0.3% from Mexico were contaminated with Salmonella [10], respectively. Salmonella was also found in watermelons imported from Costa Rica and Brazil. In Germany, out of 406 samples, three melons were contaminated with Listeria.
