1,3-PDO suppresses the flavor of certain compounds differently than PG and VG.
" it was found that certain classes of flavor compounds are better suppressed in the presence of 1,3-propanedioS, including, for example, unsaturated and saturated aldehydes (C2- C12), saturated and msaturated acids (C6-C12), saturated and unsaturated alcohols (C6-C12), ketones (C7-C10), ethyl esters, butyl esters, and aromatic hydrocarbons. Specific flavor compounds suppressed in the presence of 1,3-propaiiediol include, for example, decanoic acid, caprylic acid, caproic acid, propionic acid, acetaldehyde, butyraldehyde, propionaldehyde, hexanal, hexenal, heptanal, heptenal, octanal, citral, ethyl butyrate, ethyl caprate, ethyl decanoate, ethyl propionate, methyl butyrate, ethyl methyl butyrate, butyl butyrate, ethauol, octanol, hexanol, hexenol, heptenoi, decanoL henzakiehyde, nonanone, and octanone."
Benzaldehyde (almond, cherry, etc) is seriously compromised by 1,3-PDO even at 7% w/v in my tests.
I use 1,3-PDO but definitely do longer term steep testing whenever I feel a flavor concentrate contains the aldehydes or esters that may be suppressed by the fixative action.
Ibid: "However, it was unexpectedly found that inclusion of 1,3-propanediol uniquely modifies the flavor profile of food products or food ingredients even when 1,3- propanediol is included in such low amounts (e.g., about 0.1 to about 2 weight percent). In one aspect, the 1,3-propanediol is included in an amount such that it does not itself contribute flavor to the product. In this respect, 1 ,3~propanediol functions in the beverage and food products as a flavor adjuvant, by which is meant that the 1,3-propanediol affects the flavor or perception of flavor in the food product while not acting as a flavoring ingredient itself, in one aspect, inclusion of 1,3-propanediol results in modifying flavor release of flavor compounds in the food or beverage product. In one form, the modification of flavor release comprises suppressing the release of certain flavor compounds and, more generally, classes of flavor compounds in the product,"
I posted this from my mobile so mind any errors.