An increased AST level is usually a sign of liver disease. Liver disease is even more likely when the levels of substances checked by other liver blood tests have also increased. An increased AST level may be due to any of the following:
In order to keep itself fresh, the lettuce gives off carbon dioxide, causing a slight odour. This carbon dioxide is not harmful and the odour should disappear quickly once the salad package is opened.
In the category of natural food preservatives comes the salt, sugar, alcohol, vinegar etc. These are the traditional preservatives in food that are also used at home while making pickles, jams and juices etc. Also the freezing, boiling, smoking, salting are considered to be the natural ways of preserving food.