10/7/2023 0 Comments Washing iceberg lettuceThese results showed that inherent differences between tissues affect phenolic metabolism and browning in stored, fresh-cut lettuce. Do you need to wash a head of iceberg lettuce before eating it Yes, iceberg lettuce should be thoroughly washed in running water before eating. 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. 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. ![]() 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. Edge browning (measured with a Minolta Chroma Meter) and TPH increased in all tissues, especially in outer vascular tissue. Protein content and PPO activity remained constant. POD activity also increased steadily for the storage duration. PAL activity increased in all tissues after 1-2 days of storage and then gradually decreased. 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 activities (on a fresh weight basis) were similar in all tissues. 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. ![]() 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. 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.
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