Development of novel technologies for surface disinfection and food safety in Antep pistachios

Our country is the third largest pistachio producer in the world after the USA and Iran. Although pistachios are one of the most important agricultural products of our country, since the stages suchas laying, drying, wetting, peeling, cracking, etc. from harvest to packaging are carried out under uncontrolled conditions, the microbial load of the pistachios increases, they become contaminated with pathogenic bacteria, and the moisture content of the product cannot be controlled. Additionally, aflatoxin problems occur in products with mold contamination. Heat treatment provides microbial inactivation but damages the physical and sensory properties of the food. For this reason, technologies that provide microbial inactivation and do not harm the physical and sensory properties of food are being investigated. For this purpose, in this thesis, physical, chemical, microbiological and sensory properties of pistachios were investigated by applying Pulsed Electric Field (PEF) and Ultraviolet Light (UV) to pistachios. PEF parameters applied to pistachios; 100-300 Hz frequency, 1-8 cycles, 2.47-19.78 s duration, 2.97-71.23 J energy and 1.2-28.8 kV/cm electric field strength. As a result of the application of 71.23 J energy and 28.8 kV/cm electric field strength in pistachios, 4.73 on the Salmonella spp. population, 5.21 on the total mesophilic aerobic bacteria (TMAB) population, 5.56 on the total yeast and mold (TMK) population, and a decrease of 4.87 log cfu/g was observed in the total coliform bacteria level. In the UV application, 900 - 2700 s duration, 0.044 W/cm2 light intensity and 39.6-118.8 J/cm2 UV dose parameters were applied. As a result of these parameters, the decrease in Salmonella, total coliform bacteria, total mesophilic aerobic bacteria and total yeast-mold levels is 4.88, 4.43, 4.46 and 5.30 log cfu/g, respectively. PEF and UV application did not cause significant changes in the physical and sensory properties of pistachios (p>0.05). While PEF application decreased the total phenolic content and total antioxidant activity of pistachios, UV application increased them statistically significantly (p<0.05). While PEF and UV application increased the peroxide value of the samples, it did not cause a significant change in the titratable acidity (p>0.05). According to the results, it was determined that PEF and UV aplications can be used to provide surface disinfection and microbial inactivation in pistachios.