Some foods are better able to resist changes in pH than others. These tend to resist changes in pH since these are buffered and the ability to resist changes in pH is known as buffering capacity. The buffers are the compounds present in food that resist changes in pH and thus are important. These are especially effective within a certain pH range. Buffers permit an acid (or alkaline) fermentation to go on longer with a greater yield of products and organisms than would otherwise be possible. In general, meats are more buffered than vegetables. Contributing to the buffering capacity of meats are their various proteins. Vegetables are generally low in proteins and consequently lack the buffering capacity to resist changes in their pH by the growth of microorganisms. Hence these permit an appreciable decrease in pH with the production of small amounts of acid by the lactic acid bacteria during the early part of sauerkraut and pickle fermentations. This is desirable since it enables the lactic acid bacteria to suppress the undesirable pectin-hydrolyzing and proteolytic organisms which cause spoilage. Low buffering power makes for a more rapidly appearing succession of microorganisms during fermentation than high buffering power. Milk is fairly high in protein (a good buffer) and therefore permits considerable growth and acid production by lactic acid bacteria during the manufacture of fermented milks before growth is suppressed.