By adding oil it keeps foam as safe and desirable level. Frozen vegetables should not be thawed before pressure cooking. The only exception to this rule is corn on the cob which must be completely defrosted. One-half water is sufficient for cooking any quantity of frozen vegetable because the cooking time is so very short. Time for cooking carefully so that vegetables will not be overcooked and reduce pressure instantly.
Fresh fruits cook very quickly.
Apricots, cherries, peaches, and plums are brought to pressure to 0 pressure, then reduce pressure normally. Pears are cooked 2 minutes, then reduce normally. Pineapple takes 6 minutes then reduce normally. At altitudes of 2,000 feet or higher, use 10 lbs. This applies to canning as well as cooking.