Abstract: Bulk starter media for making cheese is prepared having internal pH control by providing in conventional starter media an amount of magnesium ammonium phosphate sufficient to maintain a pH of at least 5 for at least 20 hours during fermentation to produce a cultured bulk starter. The magnesium ammonium phosphate is less than 50% soluble at a pH of from 6 to about 7.5 of the starter media prior to fermentation. The starter media preferably contains an alkali metal tripolyphospate phage control agent, and may contain sweet whey and autolyzed yeast.