Молекулярная гастрономия для креативных шеф-поваров (англ. язык) - страница 92

Молекулярная гастрономия для креативных шеф-поваров (англ. язык)

The weight of one egg white is about 30 g. The proteins represent about 10 % (w), which is about

3 g xxxiii.

M ovalbumine = M egg prot = 45 000.

and 75 <M AA on average < 200

Hypothesis : M AA on average = 132.5

The average number of amino acid residues in a protein of ovalbumin is:

N = M ovalbumine / M AA on average = 339,62 @ 340

Ovalbumin is a protein constituted by amino acids (AA). We can calculate the length of the

protein, knowing the “length” of one AA.. Indeed, an amino acid is connected to another one by a peptid

link. By neglecting the influence of the radical, we thus know that an amino acid has the length of a

carbon-carbon link, and of a peptid connection: both of a length of the order of 1.5 angstroms.

Figure 60: Salty meringues (powder of white), with

tomato juice and Provence herbs.

59 / 63

H2N

CH

C

R

NH

O

CH

C

R

OH

O Figure 61: Two amino acids connected by a peptid link.

The length of an AA, on a polypeptide chain is thus of the order of 5 angstroms, is l = 5.10-10 m.

By estimate, we can assimilate an essential molecule of collagen to a chain constituted of n amino acids:

L = N*l = 1.70. 10-7 m

Proteins can have various sizes due to the properties of the radicals of each amino acid. We shall

thus estimate the two extreme shapes that a polypeptide chain can take; namely a thread for the most

developed shape and a cube of linked amino acids for the most compact ...

amino acid. We shall

thus estimate the two extreme shapes that a polypeptide chain can take; namely a thread for the most

developed shape and a cube of linked amino acids for the most compact shape.

In its most compact shape, such molecule would have a shape of cube whose edge is the cube

root of n. The surface of the air bubbles would be covered by such cubes.

Smin = (((L/l) 1/3)*l) 2 ;

Smin =

L

l

.c

e

o

.

o

(2/3)

l 2

Also, the most free shape would form a network of fibers of collagens, like a square of L. of

surface:

Smax = 1

2

L 2

The total surface of bubbles that can be covered by the proteins of gelatine is thus determined by

the number of structural units of collagen by the total surface considered:

Let Sm be the surface covered with the most compact shape of collagen.

Let SM be the surface covered with the less compact shape of collagen.

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