The gemara seems to imply that chametz is not a concern with flour mixed with fruit juice. Indeed, amongst other effects, sugars (which are present in fruit juice) slow gluten development. However, the physical processes in bread-rising are complex and easily affected by many factors (ingredient proportions, temperature, etc.). In addition, physical processes such as bread-rising are generally immediate and continuous , which means a certain amount of rising is not considered halachik chimutz.
Ultimately, is the concept of chametz to be treated as a purely halachik construct independent of the physical phenomenon of yeast/gluten interaction, or do we need to factor in modern scientific knowledge of the myriad influences on a physical process? Even if certain ingredients affect the chimutz-process, should we be able to estimate and adjust time-limits accordingly based on what would typically be the proportion of rising that would have occurred in a typical (ancient) bread by the time limit of the Talmud? Do any halachik sources discuss this issue, e.g. with regard to chametz nuksheh/matza ashira?