# Effects of plasma-activated lactic acid on the physicochemical properties and volatile organic compounds of refrigerated tilapia fillets

## TL;DR

A new plasma-activated lactic acid method preserves tilapia fillets by slowing microbial growth and oxidation, extending shelf life by four days.

## Contribution

A novel plasma-activated lactic acid treatment is introduced for preserving fish quality through multi-target mechanisms.

## Key findings

- PALA reduced microbial counts to 6.41 Log CFU/g and TVB-N to 15.26 mg/100 g after 7 days of storage.
- PALA suppressed myofibrillar protein oxidation, reducing carbonyls by 52% and increasing sulfhydryl content by 53%.
- PALA improved flavor by reducing spoilage aldehydes while retaining fresh-flavor compounds.

## Abstract

This study developed a novel plasma-activated lactic acid (PALA) strategy (650 W, 90 s, 0.0625 % lactic acid) to preserve refrigerated tilapia fillets. Mechanistically, PALA-generated reactive nitrogen species, particularly •NO₃/•NO₂, effectively stabilized pH and inhibited microbial proliferation, maintaining counts at 6.41 Log CFU/g and TVB-N at 15.26 mg/100 g after 7 days of storage. The synergy between acid and reactive oxygen nitrogen species significantly delayed lipid oxidation (TBARS reduced by >40 %) and protein degradation, preserving texture and color. PALA suppressed myofibrillar protein (MP) oxidation, reducing carbonyls and surface hydrophobicity by 52 % and 20 %, respectively, while increasing sulfhydryl content by 53 %, as confirmed by SDS-PAGE showing attenuated myosin/actin degradation. Volatile profiling revealed PALA reduced spoilage aldehydes (heptanal, nonanal) while retaining fresh-flavor aldehydes (octanal, dodecanal). This multi-target action extended the shelf life by 4 days, with nitrate/nitrite residues within safety limits, establishing PALA as an innovative, synergistic preservation technology for aquatic products.

Unlabelled Image

•PALA extended tilapia shelf life by 4 d via inhibiting microbial growth.•PALA delayed lipid/protein oxidation with lower TBARS and TVB-N.•PALA reduced MP carbonyls and surface hydrophobicity, preserving protein integrity.•PALA improved flavor by suppressing spoilage aldehydes and retaining fresh compounds.

PALA extended tilapia shelf life by 4 d via inhibiting microbial growth.

PALA delayed lipid/protein oxidation with lower TBARS and TVB-N.

PALA reduced MP carbonyls and surface hydrophobicity, preserving protein integrity.

PALA improved flavor by suppressing spoilage aldehydes and retaining fresh compounds.