Cheese, butter, sauerkraut and pickles are all products of fermentation. Fermentation is how people preserved and enhanced the nutritional composition and digestibility of many foods. Process's like canning, freezing, refrigeration, dehydration, bleaching(flour,sugar,salt) and pasteurization, to name a few, are all examples of modern food process's that typically alter the food in some way that favors shelf life, cost or convienence over nutrient density.