Preheat oven to 350 degrees
Peel and core pear; finely chop. Sprinkle lemon juice over pear in small bowl and set aside.
Combine flour, brown sugar, ginger and allspice in a large bowl, mixing well. Make a well in center of mixture.
In a separate bowl, dissolve baking soda in buttermilk; stir in molasses, oil, eggs and pear mixture.
Add to dry ingredients, mixing just until moistened.
Spoon batter into greased muffin pans, filling 2/3 full. Bake at 350 degrees for 15 to 20 minutes.