Panlop Sintuya. Pesticide residues degradation of dried chili by gaseous ozone fumigation. ปริญญาโท(Doctor of Engineering in Food Engineering). มหาวิทยาลัยแม่โจ้. สำนักหอสมุด . : Maejo University, 2020.
Pesticide residues degradation of dried chili by gaseous ozone fumigation
Abstract:
Due to the excessive use of pesticides in current agricultural farming, the products are normally contaminated with pesticide residues. Gaseous ozone fumigation is a technique that could reduce pesticides efficiently. The objective of this work was to study the effects of ozone fumigation on pesticide residue degradation in dried chili and to study the potential for scaling up ozone application.
The first part was conducted by studying the degradation of six pesticides, namely diazinon, malathion, chlorpyrifos, profenofos, ethion, and triazophos. The study also determined the degradation kinetics of pesticide residues, degradation half-life period (t₁/₂), and dried chili qualities. This includes total phenolic compounds, antioxidant properties, water activity, color, capsaicin content, and physical properties of the chili surface after gaseous ozone fumigation treatment.
Results showed that after 8 weeks of storage, the pesticides were naturally degraded in the range of 2846% with a t₁/₂ in the range of 66.6120.9 days. After dried chili was fumigated with gaseous ozone for 30 minutes in a pressurized tank, pesticide residues exhibited degradation in the range of 4569% with a t₁/₂ in the range of 17.432.1 minutes. Compared to natural degradation, ozone fumigation is better and more effective, degrading pesticides by up to 99.9%.
Furthermore, ozone fumigation didnt significantly affect (p ≥ 0.05) chili surface morphology, total phenolic compounds, antioxidant properties, water activity, color, and capsaicin content of dried chili.
In the second part, vertical force air circulation (VFA) was applied to the ozone fumigation process, and a study of dimensionless parameters was conducted to determine the potential for system scale-up. The Buckingham π-theorem was applied to obtain dimensionless parameters for the VFA fumigation analysis.
It was found that the Reynolds number (Re) correlated with hydraulic diameter and pressure drop. The reduction of chlorpyrifos residue under gaseous ozone fumigation using the VFA technique was in the range of 4977% throughout the vertical stacking column of chili. Moreover, ozone fumigation with VFA was able to improve degradation efficiency by 28% and save operation costs by 34% compared to conventional ozone fumigation.
The relationship between pesticide residue degradation and dimensionless parameters could be used for commercial scale-up in terms of stacking height, air flow rate throughout the chili basket, and pressure drop. The findings from this study provide evidence of the benefits of gaseous ozone fumigation in reducing pesticide residues in dried chili using the VFA system, which can be scaled up for commercial application.