MA Chen, LI Jian-guo, CHENG Jing. Behaviour of Salmonella sp. on fresh-cut vegetables and predictive models for growth[J]. Science and Technology of Food Industry, 2016, (04): 123-127. DOI: 10.13386/j.issn1002-0306.2016.04.015
Citation: MA Chen, LI Jian-guo, CHENG Jing. Behaviour of Salmonella sp. on fresh-cut vegetables and predictive models for growth[J]. Science and Technology of Food Industry, 2016, (04): 123-127. DOI: 10.13386/j.issn1002-0306.2016.04.015

Behaviour of Salmonella sp. on fresh-cut vegetables and predictive models for growth

  • In order to investigate the behaviour of Salmonella in raw-eaten vegetables or seasoned vegetables,a cocktail of two serovars(Salmonella enteritidis ATCC 13076 and S. newport ATCC 6962) were spot inoculated into fresh-cut vegetables(garlic sprout,cilantro,tomato,cucumber and shallot) with four inoculum levels(0.1,1.0,2.0 and 3.0 log CFU/g). Growth kinetics of Salmonella in fresh-cut cucumber at different temperatures were also studied and predictive models were used for fitting the growth data. Results indicated that no obvious growth of Salmonella was observed in all the tested vegetables at 4 ℃ for 6 days. At 28 ℃,growth potential(δ)of Salmonella in all tested vegetables were between 3.39 and 5.28 at the high inoculum levels of 2.0 and 3.0log CFU/g,indicating good growth of Salmonella in all vegetables(maximum populations>7.0 log CFU/g). At1.0 log CFU/g inoculum levels,Salmonella grew well in all tested vegetables with maximum populations of about 5.0 log CFU/g,except in cucumber at the low inoculum levels of 0.1 log CFU/g,Salmonella grew only in tomato and shallot(δ >0.5 log CFU/g),and no obvious growth was observed in other three vegetables(δ <0.5 log CFU/g). Growth curves for each culture condition in cucumber were built separately by fitting data to the Baranyi model. The results indicated that specific growth rate(μmax) of Salmonella in fresh-cut cucumber were 0.026,0.11,0.14 and 0.29 h-1at 7,15,20 and 25 ℃ respectively and lag time was 24.33 h and 9.44 h at 7 ℃ and 15 ℃. However,there was no lag time at 20 ℃ and 25 ℃. The Ratkowsky square-root model was used to describe maximum growth rate as a function of storage temperature and the mathematical models were validated. Thus,vegetable kinds,inoculum dose and storage temperature all had an impact on the behaviour of Salmonella in fresh-cut vegetables.
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