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Scientifically speaking, white is a highly complex colour interrelated to several physical, physiological and neuronal processes. The quality of white pigments is often described by their whitening intensity or opacifying effect. Objects appear white when they diffusely reflect the full spectrum of white light. Should one or more spectral colours not be reflected but absorbed, then the object will appear coloured. The amount of light reflected determines how intensely white an object appears. The amount of reflection depends on two key factors, i.e. the refraction and the particle size of the object (scattering)1. A very neat example is the fact that crystal sugar appears white, but icing sugar appears much whiter. The stronger whitening effect is only due to the difference in particle size.
Incorporation of Air
Crystallisation of e.g. sugar, polyols or fats
Incorporation of white food pigments
Beating an egg white transforms a transparent viscous liquid into a white mass. The same effect is used in the production of marshmallows, when air is incorporated into a sweetened gelatine-containing mass. The physical reason for this phenomenon is the formation of small pockets of air within the mass, causing the formation of small 'particles' with a difference in refractive index, air against sugar and gelatine, at which interface the white light is refracted and scattered.
The second option to whiten a product is to use sugars and polyols. When applying those to the surface of products in thin layers, they have a tendency to produce small crystals which refract and scatter light. Soft and hard coated confectionary products take advantage of this phenomenon.
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The third option of whitening a food product is the incorporation of a whitening pigment. Calcium carbonate (INS 170) as whitening additive is allowed in Europe and in most parts of the world. The two products differ in their chemical stability and whitening power. The reflectance of titanium dioxide is about 3 times higher than that of calcium carbonate against an air interface when used in, e.g. coated confectionary, and about 10 times higher in a low dry substance aqueous environment, e.g. salad dressing.
Both whitening additives, namely INS 170 and INS 171, face several challenges. Titanium dioxide is under pressure and calcium carbonate is instable in acidic environments. Due to this, it is not urprising that some product developers are seeking alternative solutions to whiten or opacify their respective products.
In order to cater to this need and address these challenges, Sensient has developed the global Avalanche platform. The innovative Avalanche portfolio is a range of alternatives to Titanium Dioxide and offers strong whitening or opacifying effects. The products are designed to offer solutions for most regions in the world in a large variety of applications including confectionery, instant drinks, sauces and pet food.
Complementing existing solutions with whitening effects in panning, we are now expanding the product range and introduce ingredient systems that can be both starch- or mineral-based and that remain heat, light and pH stable leading to the desired shades of white. The dedicated food technologists in our Application Service Centre will assist to solve any questions or challenges that you may have in mind to find the best suitable match. For those interested in learning more about using Avalanche, please do not hesitate to request a consult, or request a sample, if you are ready to begin trial work.
1The effect caused by the difference in refractive index was described by Augustin Jean Fresnel, the combined particle size and refractive index effect by Gustav Mie.
Your paint base can, for the vast majority of the colours you can buy in stores, be made from one of two formulations. Both are an identical blend of vinyl acetates, that are the binder, and all the other ingredients that get added to it to give weather resistance, water resistance, gelling ability and such, creating the base compound. Then they mix in filler materials, which are there to give bulk and provide the gap filling and levelling ability. For those intended to be tinted dark colours, the so called deep tint base, this is finely powdered chalk, added along with magnesium oxide powder, so as to allow a dark colour tint to predominate the finish colour.
For those that are destined for light bright tint there is a lot of titanium dioxide added, as a white reflective part, along with the other chalk and magnesium oxides, so that light is reflected off it well, giving you the base of white PVA paint, which is the base coat that your lighter colours are tinted with.
In the store, or at the factory, if they are making bulk batches of paint, or a single can in the store, you get a colour pack added to the base, and then mixed to disperse it through the bulk liquid. The colours are generally composed of large amounts of the colour pigments, organic molecules in the most part, finely ground, and mixed with the acetate base and stabiliser that is the base without the filler, and deeply concentrated to a consistent particle density, and then packaged in smaller paint tins, for retail mix typically 1l plastic tubs. Then at the store level you have your paint swatches, which are all coded as to the colour, and that colour number is used by the mixing computer (almost invariably computer controlled these days, rare to find a shop with a manual mixmaster and a recipe book telling you the info for each base, quantity and colours to add to get the desired colour) to drive an automated dispenser, which takes a carousel of the various colours, all regularly stirred so the pigments do not settle out. Then it rotates the carousel to the desired colour, and activates a precision pump that dispenses the volume of pigment needed per colour, from 0.1ml to 200ml which is dropped direct into the opened can underneath. After the dispensing the can is sealed again, and placed in a shaker to blend the individual colours into a single homogenous paint in the can, and also mix the settled pigments in the can as well.
Your colour will be made from up to 10 different volumes of pigment, often containing black, brown and green, even for the predominantly blue colours, just to shift the colour to the right shade to match the colour samples.The 20 odd mix colours are also added to the oil based paints, where the PVA base disperses in the oil base, and still provides a similar colour, though your colour there will have a different formulation, adjusted for the different base, to get a very close colour match irrespective of base component. There is slight variability between batches, which is why you get told by professional painters to order all the colour you need as a single batch, or at least paint a room with the same batch, so as to not have slight colour shifts in the pastel tints. And yes, one of the colour tints is actually near pure titanium dioxide, added to make the brighter shades of light pastel paints, adding extra reflection to the paint.
An anecdote is the one new complex decided on the colour they wanted to use outside, which resulted in them needing to use 1.2l of the phthalo blue tint per 25l bucket, so they actually got 26l per bucket of paint. They ordered so much that the paint mixer shop, who were supplying them with the paint on demand, was not using the 1l tubs of phthalo blue to mix, instead receiving it in 200l drums, and using a drum pump and a bucket, to move it to next to the mixmaster, and then pouring in 2l at a time, while the machine was dispensing. They never got the blue stains off that area of floor. I wanted a 5l paint mix, so simply grabbed one of the older staff who knew how to use the manual mixmaster and the recipe book, as I had already gotten the 5l can of deep tint base off the shelf, I knew the base needed. They had a pallet of 25l buckets ready to go out, and another under construction, with 10 stacked there for the rest of the week. They were getting 20 pallets a week of just the one base for this order, and it took 3 months to complete.