Silvestry Acosta, Aimee

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    Análisis de riesgo del agua utilizada en sistemas hidropónicos para el cultivo de Latuca sativa L. en Puerto Rico
    (2018-05) Silvestry Acosta, Aimee; Negrón, Edna; College of Arts and Sciences - Sciences; Orellana Feliciano, Lynette E.; Ríos Hernández, Luis A.; Pérez Muñoz, Fernando; Department of Food Science and Technology; Colón Ramírez, Silvestre
    Foodborne diseases cause 48 million people annually to suffer health problems due to the presence of pathogens in their food. This represents a concern in terms of the people affected and the economic cost for public health, which could be prevented (Olaimat y Holley, 2012). Outbreaks of food-borne diseases associated with fruits and vegetables continue in the United States and worldwide. Although the source of contamination of leafy vegetables has not been determined, factors such as longer shipping distances and increased time between harvest and consumption can affect the safety of the food. Likewise, high demand for these products can result in unsuitable growing areas near agricultural breeding sites. Another factor that may be a source of contamination is the water supply. Agricultural water represents a potential source of pathogenic microorganisms requiring analysis and monitoring to determine its sanitary quality. In this research, four farms located in three municipalities: Hormigueros, Lares and San Germán, P.R., which grow lettuce (Latuca sativa L.) in hydroponic systems, were selected. Three farms use well water as their water supply and one of them uses potable water. Six sampling points were established in each farm, four in the hydroponic system, one in the source of the water (well water or potable water) and one in the storage tank. The water samples were taken from the different points at different times (0-5, 15-20 and 30-35 days) during the growing period until harvest. A bacteriological count of Escherichia coli was taken using selective media like m-Endo Agar LES and m-FC agar to determine the water quality and verify if the agricultural water complied with the Food Safety Modernization Act (FSMA) - Produce Safety Rule (PSR). The isolated colonies were inoculated in MacConkey sorbitol media to detect the presence of E. coli O157:H7. After performing an ANOVA to the number of presumptive colonies of Escherichia coli isolated from the water of farms whose supply was well water (Farm 1, Farm 2, Farm 3), it was observed that there was a significant difference between the sampling points analyzed (p < 0.0001). For the sampling points distribution tank (TD), starting point (PI), middle point (PM) and end point (PF) the averages of colonies were 3.39, 3.40, 3.39 and 3.35 log CFU/100mL of water respectively. The farms were not in compliance with the microbiological standards (2.10 log CFU of E. coli/100mL) established in the Produce Safety Rule (PSR) for the aforementioned points. For the sampling points of the well (P) and storage tank (TA), the farms were in compliance because the averages of colonies were 0.71 and 0.55 log CFU/100mL of water respectively. The preliminary results of the farm, whose supply was potable water (Farm 4), was not in compliance with the microbiological standards at the sampling points: distribution tank (TD), starting point (PI), midpoint (PM) and end point (PF). The reported values were 3.49, 3.43, 3.46 and 3.47 log CFU/100mL of water respectively for the aforementioned points. For the tap point (G) and storage tank (TA), the farm whose supply was potable water was in compliance, because the reported values were 0.00 log CFU/100mL of water for both points. These results suggest that the problem of contamination lies in the hydroponic system. It is recommended to use chemicals such as sodium hypochlorite, calcium hypochlorite or chlorine dioxide to treat the water and the implementation and validation of a cleaning and sanitizing program in the hydroponic system to eliminate microorganisms that cause diseases. Another strategy to treat water could be heat sterilization, ozone injection, exposure to ultraviolet radiation (UV-C), membrane filtration or ultrasound (US). In addition to these results, the presence of E. coli O157: H7 in the analyzed water samples were preliminarily detected for farms 1 and 3.