Preform and container with variable transmittances

An opaque preform intended for forming containers by blow molding or stretch-blow molding, the preform comprising:

• a hollow body formed from plastic material comprising at least one additive giving the plastic material the property of at least partially filtering the visible light spectrum, the preform comprising a wall forming the hollow body, the preform wall comprising a first thickness of about 1 mm to about 5 mm that is greater than a second thickness of a wall of the container, wherein one or more additive(s) give the plastic material the property of at least partially allowing the passage of light in the infrared spectrum, and in that the preform wall has, under electromagnetic radiation emitted perpendicular to the preform wall, transmittance in the visible spectrum that is substantially equal to 0% in the wavelength range of 350 nm to 520 nm, and transmittance in the infrared spectrum within a transmittance range extending between a threshold transmittance and an upper transmittance, for at least one wavelength within the range of 700 nm to 2250 nm, the threshold transmittance being equal to 5% and the upper transmittance being equal to 70%.

An opaque preform for protecting the degradation of milk's riboflavin, the preform intended for forming containers by blow molding or stretch-blow molding, and further being filled with milk comprising the riboflavin, the preform comprising:

• a hollow body formed from plastic material comprising at least one additive giving the plastic material the property of at least partially filtering the visible light spectrum, the preform comprising a wall forming the hollow body and defining a preform wall thickness of about 1 mm to about 5 mm, the container that is formed by the preform comprising a container wall thickness, wherein the preform wall thickness is greater than the container wall thickness, wherein one or more additive(s) give the plastic material the property of at least partially allowing the passage of light in the infrared spectrum, and in that the preform wall has, under electromagnetic radiation emitted perpendicular to the preform wall, transmittance in the visible spectrum that is substantially equal to 0% in the wavelength range of 350 nm to 520 nm, and transmittance in the infrared spectrum within a transmittance range extending between a threshold transmittance and an upper transmittance, for at least one wavelength within the range of 700 nm to 2250 nm, the threshold transmittance being equal to 5% and the upper transmittance being equal to 70%.