Welcome to FST 639 – Food Polymer Science
Fall 2009
Brought to you by Oregon State University’s Dept of Food Science and Technology
and
Dr Andrew Ross
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A fluid that’s macromolecular
Is really quite weird — in particular
The abnormal stresses
The fluid possesses
http://www.youtube.com/watch?v=npZzlgKjs0I
Food polymers are all around us and are major contributors to the nutritional value and palatability of all sorts of naturally occurring and processed foods …
http://vimeo.com/3830864
What are these food polymers ?
You are intimately familiar with them already even if you don’t recognize it: starch, proteins from jello to tofu to prime-rib, and indigestible polysaccharide fibers of all different kinds from cellulose to pectin to beta-glucans to arabinoxylans are with us at all times.
Food polymers provide nutrition, we do need calories and starch does a great job. But starch also contributes to food’s deliciousness. The delicate and elastic texture of Udon noodles comes from selecting flour milled from wheat which has a naturally lower abundance of the linear poly-glucose molecule – amylose – in its starch. The body of many sauces and soups is built by starch.
Delicious udon
Flickr “Chotda”
Food polymers provide another sort of nutrition. By being indigestible by dent of the configuration of their linkages, many types of polysaccharide provide needed fiber in our diet. But indigestible polysaccharides are crucial to the texture of many natural and manufactured foods.
The cell walls we rely on to provide structure [and texture] in fruits and vegetables are primarily built from these molecules. But, polysaccharides can also be a hinderance to processing, even in “traditional” foods. For example, a pectin-based mucilage needs to be removed from coffee beans during cherry processing otherwise undesirable tastes can occur in the finished products. Another example, there is the potential for filtration problems in brewing caused by excessive beta-glucan in the barley malt as a result of their immense capacity to build viscosity in solutions even at very low weight concentrations, but these same beta-glucans, in barely or oats contribute positively to human health.
And yet another group of polymers: we need protein to supply us with amino acids. But the textures of meats are thoroughly dependent on the size, reactivity, and water holding capacities of proteins.
So why don’t we just study starch, and fiber, and protein seperately?
Because they have some critical characteristics in common and these characteristics drive a lot of their behaviours.
What are some these characteristics ?
Polymers are big – this is the crucial family resemblance, synthetic polymers behave more like biopolymers than they don’t.
They get tangled up – a function of being really big [well from a molecular viewpoint]. More on entanglement.
They take up a lot of space in a solution – another function of being really big.
Attribution: Alexis Monnerot-Dumaine
From this it can be argued that…
The physical size, solution conformations, and gelling properties of polymers are of equal or greater importance, in general, than their chemistry
And they have some primary behaviors that are of interest to us in an advanced class.
-Thickening properties
-Flow behaviors
-Gel forming abilities
We'll be looking at some formal ways of thinking about polymers that inform their primary behaviors (e.g. polydispersity; the differences between composition, configuration, and conformation; random walk conformation of polymer coils; the self-avoiding random walk conformation, the effects of branching on the rise of viscosity with size and or concentration, and the relationships between conformation and physical properties among others)
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