Isolation of Aroma-Bearing Material from Lactobacillus helveticus Culture and Cheese

In whey permeate supplemented with amino acids and inoculated with Lactobacillus helveticus, methionine was necessary for good aroma development. The aroma of Lactobacillus helveticus cultures could be removed by passing the culture fluid through either acid or basic ion-exchange resins. When the ion-exchange resins were eluted with appropriate volatile acid or base and the eluates were evaporated, the residues slowly generated volatile aroma compounds. Several acetamides were identified in culture extracts. The culture eluates from acid ion-exchange resins were fractionated into a caramelized-burned and a cereal-like component. The burned component was a complex of carbonyls with amino acids, and the burned flavor was attributed to 2,5-dimethyl-4-hydroxy-3[2H] furanone. The cereal component contained a number of volatile amines among which pyr-rolidine had the greatest aroma impact. Various pyrazines, indole, and skatole also were identified. Aqueous cheese extracts yielded aroma-bearing fractions that behaved like the culture aromas on ion-exchange chromatography. The cheese extracts contained aromas with the same gas chromatographic retention times as those in the cultures.