Volatile Composition and Sensory Profile of Lactose-Free Kefir, and Its Acceptability by Elderly Consumers.

Lactose-free products are crucial in the diet of lactose-intolerant elderly consumers, one of them being kefir due to its unique chemical composition and diversity of valuable microflora. The study aimed at determining the volatile compound profile and the corresponding sensory attributes of lactose-free kefir (LFK) as compared with the traditional one (TK). The perception of main sensory attributes and hedonic acceptability of LFK by elderly were also studied. The LFK contained two times more ketones, especially 3-hydroxy-2-butanone and 2,3-butanedione, that probably contributed to the high intensity of creamy aroma. A substantial share of acetic acid in LFK was not associated with high intensity of sour aroma, probably being masked by the creamy aroma, perceived as dominating. LFK was sensed as sweeter and more milky than the traditional one. The intense sweet taste of LFK was due to higher amounts of glucose and galactose than in TK, and was perceived as "just about right" by 63% of elderly subjects in the just-about-right (JAR) scale. The lower acidity of LFK than that of TK, assayed both instrumentally and by sensory assessment, was highly appreciated by 73% of elderly subjects as "just about right" in JAR scale. These two taste attributes dominated in liking the lactose-free kefir by elderly subjects.