The Hershey Process milk chocolate used in these bars uses fresh milk delivered directly from local farms. The process was developed by Milton Hershey and produced the first mass-produced chocolate in the United States. As a result, the Hershey flavor is widely recognized in the United States, but less so internationally, especially in areas where European chocolates are more widely available. The process is a trade secret, but experts speculate that the milk is partially lipolyzed, producing butyric acid, which stabilizes the milk from further fermentation. This flavor gives the product a particular sour, "tangy" taste which the US public has come to associate with the taste of chocolate, to the point that other manufacturers often add butyric acid to their milk chocolates.[1] The American bar's taste profile was not as popular with the Canadian public, leading Hershey to introduce a reformulated Canadian bar in 1983.[2]
Until 2015, Hershey also added polyglycerol polyricinoleate (PGPR) to their chocolate which contributed to the difference in taste between Hershey chocolates and European chocolates.
