Abstract
Cut tissues from distinct anatomical locations in iceberg lettuce (Lactuca sativa L.) were subjected to washing in cold (4 degrees C) and warm (47 degrees C) water with or without chlorine to assess their propensity to discoloration during storage. Total protein (Bradford method) and phenolic (TPH; Folin-Ciocalteu method) contents and polyphenol oxidase (PPO; spectrophotometric method using catechol as a substrate), peroxidase (POD; guaiacol substrate), and phenylalanine ammonia-lyase (PAL; phenylalanine substrate) activities were determined in photosynthetic and vascular tissue from outer and inner leaves. Unprocessed photosynthetic and inner leaf tissues had significantly higher (P < 0.05) levels of protein and TPH and PPO and POD activities than vascular and outer leaf tissues. PAL activities (on a fresh weight basis) were similar in all tissues. Changes in browning (light reflectance measurement) and phenolic metabolism in all four tissue types were observed during aerobic storage at 5 degrees C over 10 days. PAL activity increased in all tissues after 1-2 days of storage and then gradually decreased. POD activity also increased steadily for the storage duration. Protein content and PPO activity remained constant. Edge browning (measured with a Minolta Chroma Meter) and TPH increased in all tissues, especially in outer vascular tissue. Cut photosynthetic and vascular tissues washed at 4 and 47 degrees C with and without 100 microg mL(-1) chlorine for 3 min were analyzed during 7 days in storage at 5 degrees C. Enzyme activities and accumulation of phenolics in all tissues washed at 47 degrees C were significantly (P < 0.05) lower compared to controls or tissues washed at 4 degrees C. Chlorine had no additional effect at 47 degrees C but significantly (P < 0.05) reduced browning and accumulation of phenolics in lettuce washed at 4 degrees C. These results showed that inherent differences between tissues affect phenolic metabolism and browning in stored, fresh-cut lettuce.
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Claims 9
Claim · model-written summary
Unprocessed photosynthetic and inner tissues had higher protein, TPH, PPO and POD than vascular and outer tissues.
Verbatim
e0“Unprocessed photosynthetic and inner leaf tissues had significantly higher (P < 0.05) levels of protein and TPH and PPO and POD activities than vascular and outer leaf tissues.”
t0“iceberg lettuce”
Claim · model-written summary
PAL activities were similar across tissues.
Verbatim
e0“PAL activities (on a fresh weight basis) were similar in all tissues.”
t0“iceberg lettuce”
Claim · model-written summary
PAL activity rose after one to two storage days, then declined.
Verbatim
e0“PAL activity increased in all tissues after 1-2 days of storage and then gradually decreased.”
t0“iceberg lettuce”
Claim · model-written summary
POD activity increased throughout storage.
Verbatim
e0“POD activity also increased steadily for the storage duration.”
t0“iceberg lettuce”
Claim · model-written summary
Protein content and PPO activity remained constant.
Verbatim
e0“Protein content and PPO activity remained constant.”
t0“iceberg lettuce”
Claim · model-written summary
Edge browning and TPH rose in all tissues, especially outer vascular tissue.
Verbatim
e0“Edge browning (measured with a Minolta Chroma Meter) and TPH increased in all tissues, especially in outer vascular tissue.”
t0“iceberg lettuce”
Claim · model-written summary
Warm water washing lowered enzyme activities and phenolic accumulation against cold washing or controls.
Verbatim
e0“Enzyme activities and accumulation of phenolics in all tissues washed at 47 degrees C were significantly (P < 0.05) lower compared to controls or tissues washed at 4 degrees C.”
t0“iceberg lettuce”
Claim · model-written summary
Chlorine had no additional effect at 47 degrees C.
Not reportedComparator
Verbatim
e0“Chlorine had no additional effect at 47 degrees C”
t0“iceberg lettuce”
Claim · model-written summary
Chlorine at 4 degrees C reduced browning and phenolic accumulation.
- Taxon
- lettuce
Lactuca sativae0 - Treatment
- Chlorinee0
- Outcome
- browning and accumulation of phenolicse0
- Direction
- reducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Chlorine had no additional effect at 47 degrees C but significantly (P < 0.05) reduced browning and accumulation of phenolics in lettuce washed at 4 degrees C.”
The same questions in other papers
dichlorine · disease · Lactuca sativa (garden lettuce)Results agree
1 paper in the same direction as this paper
- positive
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.