Synergistic effects of pulsed electric field and isochoric subzero temperature storage on shelf-life extension of minimally processed litchi

Combination of PEF and isochoric preservation improved shelf-life stability. • Immersion in citric and ascorbic acid solutions caused hypotonic swelling. • Phenolic compounds were better retained with PEF and isochoric preservation. • Combined PEF and isochoric preservation synergistically reduced enzymatic browning and microbial growth. Minimally processed litchi is prone to quality loss due to its high moisture content, biochemical activity, and vulnerability to microbial growth. This study examined the combined effects of PEF pre-treatment and isochoric freezing (−3 °C, 235 kPa) on the quality and shelf-life of minimally processed litchi, with additional tests using ascorbic and citric acid solutions to assess their impact on preservation. Results showed that samples treated by vacuum packaging followed by isochoric freezing (VP + IF) and PEF pre-treatment combined with vacuum packaging and isochoric freezing (PEF + VP + IF) effectively maintained tissue integrity and enhanced water retention, thereby stabilising key quality parameters, including color, pH, ascorbic acid, and total phenolics, and slight titratable acidity decreased. Notably, the PEF + VP + IF treatment exhibited more pronounced positive effects, likely due to enhanced tissue permeability and improved mass transfer. Conversely, samples treated by IVP + IF and PEF + IVP + IF exhibited hypotonic swelling, resulting in significant reductions in texture, total soluble solids, ascorbic acid content, water-holding capacity, and enzyme activity, along with a slight increase in total phenolics. Nevertheless, microbial counts decreased across all treatments, with PEF + IVP + IF achieving the lowest microbial load.