Enhancing Post-Harvest Storability of Kale Using Plasma-Sonic Treatment

Area of Science:

• Food Science
• Microbiology
• Agricultural Engineering

Background:

• Conventional produce washing often uses sodium hypochlorite (NaOCl), raising concerns about harmful residues and toxic by-products.
• There is a need for effective, non-chlorine-based decontamination methods for fresh produce to ensure food safety and quality.

Purpose of the Study:

• To evaluate the efficacy of a combined plasma-sonic treatment (plasma-activated water and ultrasound) for decontaminating kale.
• To assess the impact of this treatment on the microbial load, moisture content, and firmness of kale during storage.

Main Methods:

• Kale was treated using a combination of plasma-activated water (PAW) generated at 52 W and 14.4 kHz, and ultrasound (US) applied at 20 kHz and 250 W for 624 seconds.
• Microbial inactivation was quantified (log CFU/g), and physicochemical properties (moisture content, firmness) were measured over a 7-day storage period at 4 °C.

Main Results:

• The plasma-sonic treatment achieved a 3.2 log CFU/g reduction in indigenous bacteria, comparable to the 3.0 log CFU/g reduction by NaOCl.
• Kale treated with plasma-sonic washing maintained a higher initial moisture content (89.42%) and superior firmness compared to NaOCl-treated and untreated samples.
• The treatment demonstrated significant microbial decontamination while preserving the quality attributes of the leafy vegetable.

Conclusions:

• The combined PAW and US washing method is a promising non-chlorine alternative for fresh produce decontamination.
• This plasma-sonic intervention enhances microbial stability and maintains the physicochemical quality of leafy vegetables.
• This approach offers a safer and potentially more effective method for produce preservation.