Heat oven to 325 degrees Grease an 8 x 4 inch loaf pan with butter and line it with parchment paper so that some hangs over the sides for easy lifting later.
In a large bowl, whisk together the dry ingredients (flours, salt, and baking powder).
In the bowl of a stand mixer, paddle together the softened butter and sugar until light and fluffy (about 3-5 minutes).
Add beat each egg one at a time into the butter mixture, along with a spoonful of the dry ingredients. Repeat for all eggs. Once incorporated, add the lemon juice, vanilla extract, and remaining flour mixture and beat until the batter is stiff and can hold its shape. Remove the bowl from the stand mixer.
Spoon the batter into the loaf pan until its two-thirds full, pushing the batter into the corners. Leaving a slight indentation in the middle of the pan, sprinkle the berries on top, leaving an inch perimeter along the edge. Spoon the rest of the batter over the berries and gently spread it out smooth so that they are fully covered.
Transfer the cake to the oven and bake for about 1 hour, turning it half way through. When fully cooked, remove the cake to a rack and let cool for 10 minutes. Gently lift the cake out of pan and let it cool until room temperature.