In conclusion, increasing the fat concentration in L. casei
GBHM-21 fermented milk base to 90 g·L−1 had a significant
impact on both GBHM-21 fermentation characteristics and
the levels of FFAs, FAAs, and volatile compounds. The
increase in fat not only enhanced bacterial lipolysis but
also modulated proteolysis and the synthesis of volatile
compounds by exogenously stimulating the L. casei
GBHM-21 enzyme system. Additionally, the relationships
among fat concentration, total FFAs, total FAAs, and the
volatile compounds derived from FFAs were established.
The results of ketones and carbonyl acids are probably two
important parameters to explain the difference in volatile
compounds. The study could contribute to a better understanding
of fat application in the fermented dairy industry.
Future studies are required to establish a flavor model, evaluate
the flavor of the fermented milk base, and identify the
active enzymes in L. casei GBHM-21.