Why does my tuna Casserole turn sour?
Basic Nutrition
One cup of fresh pineapple chunks has 82 calories, 21.7 grams of carbohydrates, 2.3 grams of fiber and 16.3 grams of sugar. One cup of drained, canned pineapple chunks has 109 calories, 28.2 grams of carbs, 2.4 grams of fiber and 25.8 grams of sugar. The calories, carbs and sugar in canned pineapple are higher than in fresh pineapple because the canned fruit is typically packed in fruit juice.

I think that it is probably the pineapple affecting it. If you can buy pineapple juice, adding some of that may help the problem.
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