UV-C treatment is effective in stimulating the synthesis by broccoli of phytochemical compounds that control L. monocytogenes

The aim of this study was to investigate the effect of different doses of UV-C light as a postharvest treatment to control the attachment and subsequent growth of Listeria monocytogenes on fresh-cut broccoli. Growth of the bacteria was studied under invitro and in-vivo conditions. UV-C treated (at doses of 0, 2.5 and 5 kJ.m2) broccoli branchlets were inoculated with L. monocytogenes at various times (0h, 6h, and 24h) after treatment and tested for bacterial growth up to 8 days. Broccoli extracts obtained through fractionation and partitioning between different solvents (n-hexane, 10% methanol, n-butanol, and aqueous) were tested in-vitro against the growth of L. monocytogenes. All doses of UV-C irradiation significantly reduced the growth of L. monocytogenes in samples inoculated 24 h post treatment while only the higher dose was effective in samples inoculated 6 h post treatment. The most potent extract was the butanol extract which restricted the growth of L. monocytogenes in samples treated with 5 kJ/m2 and extracted 24 hours after treatment. Phytochemical analysis of the same samples using GC-MS techniques also confirmed that UV-C treatment induced particular chemical compounds that can restrain microbial growth. These findings confirm that UV-C treatment is effective in stimulating the synthesis of phytochemical compounds which are responsible for controlling the growth of L. monocytogenes in fresh-cut broccoli. Therefore, this treatment could be used as a hurdle technology to reduce the risk of post-harvest contaminations and to ensure microbial safety of fresh produce. ? Sources ANTIMICROBIAL EFFECT OF UV-C TREATED FRESH-CUT BROCCOLI AGAINST LISTERIA MONOCYTOGENESGamage, GR1, Wargent, J1, Palmer, J1, Heyes, JA1G.R.Gamage@massey.ac.nz1Massey University, Palmerston North, New ZealandIHC 2014, International Horticulture Congress, 17-22 August 2014, Brisbane, http://www.ihc2014.org/ Picture by galeria.dibujos.net Key wordsBr?coli? br?culi? broccoli?????????????????????????????? ??????????????????? ????????????????? brokolo??????????????? brocoli? ?????????????????? ???????????????????????????????????????????????????????? broku?y??????????????? br?colis??????????????? ?????????????????? brokoli? ????????????????? Brokkoli ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Poscosecha??????????????? postcosecha????? postharvest?????? na-oes? ?????????????? ?????????????????????? post-r?colte????? ???? ?? ???????????????? ??????????????? na-oogst???????????? post-raccolta???? Obr?bka po?????? p?s-colheita????? ???????????????????????? hasat sonras????????????????????? Ernte??????????????? ????????????????????????? ???? ?????????????????? postcollita?????????? poskliz?ov頠???? ?????? ????????????????????????????????? nakon branja?? pozberov頠?????????????????????? obdelovanje zemlje po??????????????? post-colleita????? ??????????????? pascapanen?????? ?il?onn postharvest?????? ????????????? p?c ra?as???????????? derliaus apdirbimas po lepas tuai??????????? ??????????? post-recoltare??????????????? ?????? ?????? ?????????????????