I buy guavas at a couple of my local grocers' fairly often. I particularly love them roasted with parships and filberts. I kept the last batch longer than usual, and my nice yellow guavas turned green again! Does anyone know why this would happen ... and if they are still good? How is the taste affected? These are unshriveled, of an even emerald green color, just as if they were unripe, and there is no mold.