Growing systems are of paramount importance to obtain raw material that is free of microbiological risks for use in the fresh-cut process. Using floating growing systems (FGS) could increase the safety of baby leaf vegetables (BLV) which, since over-head irrigation is not adopted, have short growing cycles. However, there is a lack of information on the microbial load of BLV at harvest, thus FGS have been used to study the effects of species (green and red lettuce (Lactuca sativa L. var. crispa); rocket (Eruca sativa Mill.); spinach (Spinacia oleracea L.)) on the level of microbial contamination at harvest (total bacterial count TBC; yeast and mold count YMC). FGS have been adopted to study the effects of microbial infection at harvest on green lettuce (Lactuca sativa L. var. crispa) throughout the growing season as well as the effects of seasonality (summer; autumn; winter). Green lettuce was used as a reference in all the experiments and was compared with red lettuce, rocket and spinach, respectively. The lettuce and spinach were grown in a continuous floating system (FL), while the rocket was grown in an ebb-and-flow system (EF). A complete nutrient solution, with 6 mM N, was supplied in all the experiments. Seasonality was found to not affect the TBC or the YMC of the lettuce, which showed an average contamination of 1.7 103 cfu g-1 and 4.7 101 cfu g-1, respectively. As the same growing conditions were adopted in each comparison, it is possible to state that the species did not affect the TBC in the comparison between the green lettuce and red lettuce (average contamination: 7.4 103 cfu g-1) or in the comparison between green lettuce and rocket (average contamination: 7.3 103 cfu g-1), while it did affect the TBC in the comparison between the green lettuce and spinach. A greater contamination was found in spinach (1.0 106 cfu g-1) than in green lettuce (4.4 102 cfu g-1). The species did not affect the YMC in the comparison between the green lettuce and red lettuce (average contamination: 2.7 101 cfu g-1) or in the comparison between the green lettuce and rocket (average contamination: 1.1 102 cfu g-1), but it did affect the YMC in the comparison between the green lettuce and spinach. A greater contamination was found in spinach (8.2 102 cfu g-1) than in green lettuce (4.6 100 cfu g-1).
The floating growing system can assure a low microbial contamination of baby leaf vegetables at harvest
Nicola S.First
;Pignata G.;Tibaldi G.
2018-01-01
Abstract
Growing systems are of paramount importance to obtain raw material that is free of microbiological risks for use in the fresh-cut process. Using floating growing systems (FGS) could increase the safety of baby leaf vegetables (BLV) which, since over-head irrigation is not adopted, have short growing cycles. However, there is a lack of information on the microbial load of BLV at harvest, thus FGS have been used to study the effects of species (green and red lettuce (Lactuca sativa L. var. crispa); rocket (Eruca sativa Mill.); spinach (Spinacia oleracea L.)) on the level of microbial contamination at harvest (total bacterial count TBC; yeast and mold count YMC). FGS have been adopted to study the effects of microbial infection at harvest on green lettuce (Lactuca sativa L. var. crispa) throughout the growing season as well as the effects of seasonality (summer; autumn; winter). Green lettuce was used as a reference in all the experiments and was compared with red lettuce, rocket and spinach, respectively. The lettuce and spinach were grown in a continuous floating system (FL), while the rocket was grown in an ebb-and-flow system (EF). A complete nutrient solution, with 6 mM N, was supplied in all the experiments. Seasonality was found to not affect the TBC or the YMC of the lettuce, which showed an average contamination of 1.7 103 cfu g-1 and 4.7 101 cfu g-1, respectively. As the same growing conditions were adopted in each comparison, it is possible to state that the species did not affect the TBC in the comparison between the green lettuce and red lettuce (average contamination: 7.4 103 cfu g-1) or in the comparison between green lettuce and rocket (average contamination: 7.3 103 cfu g-1), while it did affect the TBC in the comparison between the green lettuce and spinach. A greater contamination was found in spinach (1.0 106 cfu g-1) than in green lettuce (4.4 102 cfu g-1). The species did not affect the YMC in the comparison between the green lettuce and red lettuce (average contamination: 2.7 101 cfu g-1) or in the comparison between the green lettuce and rocket (average contamination: 1.1 102 cfu g-1), but it did affect the YMC in the comparison between the green lettuce and spinach. A greater contamination was found in spinach (8.2 102 cfu g-1) than in green lettuce (4.6 100 cfu g-1).
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