Hydrolyzed vegetable proteins: a formulator's guide. (part II)

In Part I of this article, we reviewed the definition of a protein and discussed some of the ways in which proteins differ from each other. The present article attempts to relate several differences in hydrolyzed proteins, components of their "character," to their performance properties as skin and hair conditioners. It begins by reviewing how proteins differ, and then continues to outline several of these differences affects. The focus will be on hydrolyzed vegetable proteins (HVPs), but also include appropriate comparison information with hydrolyzed animal proteins (HAPs).

Figure 1 reviews the basic parameters which will distinguish HVPs, HAPs and their derivatives from each other. The first three subjects will then be examined in some detail, along with the main functional conditioning properties we might expect to result from variations in these basic parameters. Hopefully, this will provide us with a road map in our attempts to relate protein structure to function.

PROTEIN SOURCE

While ostensibly source of the protein is the most important parameter. in practice we find that the source alone may be one of the least important parameters affecting conditioning function. Certainly, there are important exceptions and qualifications to this statement, and it may be best to deal with these exceptions first before proceeding to the more general case.

First, it may be helpful to remind ourselves that we are dealing with HVPs, HAPs and their derivatives from a cosmetic perspective. We are not dealing with "native proteins" that exist in their original, perhaps biologically active, state. Our interest is in a class of compounds which condition and moisturize the skin and hair -- cosmetically acceptable claims and functions. Our focus will then remain on the chemical structure and performance, as opposed to the biological.

Stripped of this mysticism, and armed with a small amount of information concerning their method of manufacture, it will soon become clear why a hydrolyzed wheat protein of the same molecular weight, electrical charge, and side groups as a hydrolyzed collagen protein may not differ appreciably in performance.

The first step in the manufacture of hydrolyzed proteins is, of course, hydrolysis. In this case, hydrolysis refers to the breaking of the peptide bonds which normally join the amino acids together. This is typically done through the action of strong acids or bases, or enzymes. In most cases, not all these bonds are broken, but a great number are. The result is to transform an insoluble native protein with a molecular weight in the millions, to an HAP or HVP with a molecular weight in the thousands. This will inevitably lead to the loss of their original biological function, since what we have left are only fragments of the starting native protein. These fragments begin to look much like each other despite the differences in the starting protein. This is how a hydrolyzed wheat protein ends up looking similar to a hydrolyzed collagen or keratin protein. And what looks similar will act similar, other parameters being equal.

Just how similar or dissimilar these fragments appear will depend upon the molecular weight and the amino acid analysis. If we assume for the sake of our …