Efficacy of dual-frequency ultrasound and sanitizers washing treatments on quality retention of cherry tomato

Refrigeration is an effective means of reducing losses in fresh fruit; however, its efficacy as a means of preservation is mostly limited to crops that are not vulnerable to chill injury. Cherry tomato is one of these crops where other supporting processes or storage alternatives are sought. The effect of 10-min post-harvest treatment of cherry tomato with individual or combined application of dual-frequency ultrasound (20/40 kHz) and chemical sanitizers was investigated. The sanitizers used are 200 mg/L sodium dichloroisocyanurate (SD), 40 mg/L peracetic acid (PAA), 40 mg/L peracetic acid with 5% H₂O₂ (PAAH), and 5% hydrogen peroxide. The results showed that the treatments significantly reduced the natural microbiota (aerobic mesophiles and yeasts and molds) within the values of 0.29–3.10 log CFU/g. The highest inactivation was observed for the PAAH and ultrasound when applied as an individual (2.08–2.32 log CFU/g) and combined (3.07–3.10 log CFU/g) treatment. Also, the ultrasound and combined treatment resulted in higher retention of the total phenolic, and flavonoid contents, but with a loss in firmness of the cherry tomato. Nevertheless, during storage, the treatments when compared with the untreated samples, impede the loss in firmness. The other quality parameters such as pH, total soluble solids, titratable acidity, and maturity index were not affected, which signified that irrespective of the treatment, similar changes take place on the fruit during storage, especially in both control and chemically treated fruit. The combination of 40 mg/L PAAH and 20/40 kHz for 10 min caused ≥3-log CFU/g reduction of the natural microbiota. It mitigated the senescence of the cherry tomato during the refrigerated storage (4 °C), which thereby increased the shelf-life. The results obtained at the end of the storage thereby indicated that the combined treatments could guarantee microbial safety and retain the quality of the cherry tomato.