ผลของคลื่นเหนือเสียงร่วมกับน้ำอิเล็กโทรไลต์ต่อการลดเพลี้ยอ่อนและจุลินทรีย์ที่ปนเปื้อนในถั่วฝักยาวหลังการเก็บเกี่ยว

Abstract

To study the effects of ultrasonic waves (US) at various frequencies of 43, 200, 500 and 1000 kHz in combined with electrolyzed water (EW) to remove aphid and microbial contaminant in yardlong bean after harvest. Electrolyzed water was prepared from 5% NaCl solution and generated from electrolyzed water generator, which contained in separated chambers: to produce ER water and it was diluted to reach final concentration of 250 ppm and EO water with free chlorine at 10, 20, 30, 40 and 50 ppm. Then the mixture of ER and EO or EW (Electrolyzed Water) was measured pH and Oxidation Reduction Potential (ORP). The first approach, the effect of US wave on aphid mortality was studied. The results showed washing yardlong been with US wave at a frequency of 1000 kHz and washing with EW water (ER concentration of 250 ppm mixed with EO water at 30 ppm) was the most effective to kill the aphid. The combination treatments of US wave and EW water had synergistic effect in the elimination of aphids to 63.68%. Secondly, the effective of US wave combined EW water on microbial decontamination were examined, When compared with control, combined treatment of US wave frequency of 43 kHz with EW water (ER concentration of 250 ppm mixed with EO concentration 30 ppm) had the best results to reduce total amount of microorganisms, total coliform bacteria, yeast and mold whereas Salmonella contamination was not detected. After treated with US wave and EW water, then stored in 5 °C for 14 day. It was found that there were no significantly changes on weight loss, color change, chlorophyll content, disease percentage, wilting percentage and consumer acceptance of yardlong bean throughout the storage period.