  The physical structure of a nuclear flame is a basic ingredient of the theory
of Type Ia supernovae (SNIa). Assuming an exponential density reduction with
several characteristic times we have followed the evolution of a planar nuclear
flame in an expanding background from an initial density 6.6 10^7 g/cm3 down to
2 10^6 g/cm3. The total amount of synthesized intermediate-mass elements (IME),
from silicon to calcium, was monitored during the calculation. We have made use
of the computed mass fractions, X_IME, of these elements to give an estimation
of the total amount of IME synthesized during the deflagration of a massive
white dwarf. Using X_IME and adopting the usual hypothesis that turbulence
decouples the effective burning velocity from the laminar flame speed, so that
the relevant flame speed is actually the turbulent speed on the integral
length-scale, we have built a simple geometrical approach to model the region
where IME are thought to be produced. It turns out that a healthy production of
IME involves the combination of not too short expansion times, t_c > 0.2 s, and
high turbulent intensities. According to our results it could be difficult to
produce much more than 0.2 solar masses of intermediate-mass elements within
the deflagrative paradigma. The calculations also suggest that the mass of IME
scales with the mass of Fe-peak elements, making it difficult to conciliate
energetic explosions with low ejected nickel masses, as in the well observed
SN1991bg or in SN1998de. Thus a large production of Si-peak elements,
especially in combination with a low or a moderate production of iron, could be
better addressed by either the delayed detonation route in standard
Chandrasekhar-mass models or, perhaps, by the off-center helium detonation in
the sub Chandrasekhar-mass scenario.
