Heat shock and UV-C abiotic stress treatments as alternative tools to promote fresh-cut carrot quality and shelf-life

Abstract

Abiotic stress treatments, heat shock (HS_100 ºC/45 s) and UV-C (0.1-5 kJ.m-2), and two passive modified atmosphere packaging conditions were evaluated under the hurdle concept as alternative approaches to the standard processing of fresh-cut carrot (FCC). The significant phenolic accumulation, via phenylalanine-ammonia lyase activation, showed to be independent on key factors contributing to raw material bioactivity, cultivar and crop season, but dependent on treatments intensity (HS_[100 ºC/45 s], UV-C_[2.5 kJ.m-2]) and on oxygen availability (>2%). The low decontamination efficiency of UV-C_[2.5 kJ.m-2] as single hurdle was similar (p>0.05) to that of sodium hypochlorite (<1 Log10 cycle in aerobic mesophilic microflora) and was responsible for FCC early sensorial rejection (<7 days), regardless packaging conditions. The simultaneous effects on microbiological control and reduced metabolic rates yielded by HS_[100 ºC/45 s] significantly contributed to the preservation of FCC sensorial quality allowing the full recovery (100%) of raw materials’ phenolic levels (≥5 days, 5 ºC), with no synergic effects in the combination with UV-C, resulting in FCC shelf-life extension by two-fold (14 days, 5 ºC) when using a bi-oriented polypropylene micro-perforated film