The results have shown that the moisture content drops linearly during maturation, while aw is constant (aw = 1.000) until about 36–38 % of grain moisture, and only after this moisture level, does it start to decrease. This would seem to indicate that: (i) the water that is initially lost is all surface or loosely held water and aw does not actually start dropping until late on the maturation phase, and that, (ii) consequently the conditions remain favourable to microbial growth and development until the last grain maturation phases. The measurements conducted at the three temperatures indicate that the effect of temperature only starts to be evident at a grain moisture content of about 30 % : after this level, the higher the temperature, the higher the water activity at the same moisture content. Moreover, the lower the moisture content, the more the temperature influence aw.