Also in this case, as for nano-calcium carbonate, it was possible to dissolve the deacidifier in a solvent unable to dissolve the normal calcium propanoate. In the tests on original documents, a concentration of 3% w/v of nanopropanoate in propan-2-ol was used, and the product was applied by brushing it from the recto side of the documents.
(b) Laboratory iron-gall ink before and after treatment with calcium propanoate. All the typical peaks of the ink (around 576 [cm.sup.-1]: band related to the formation of iron-cellulose complex; 1431 [cm.sup.-1]: COO- sym.
pH before treatment pH after treatment Paper: 6.5 [+ or -] 0.1 Paper: 10.1 [+ or -] 0.1 Ink: 5.1 [+ or -] 0.1 Ink: 9.9 [+ or -] 0.1 Colour coordinates before Colour coordinates after treatment treatment Paper: Paper: L* = 91.79 [+ or -] 0.12 L* = 90.39 [+ or -] 0.36 a* = +0.08 [+ or -] 0.02 a* = +0.19 [+ or -] 0.03 b* = +11.15 [+ or -] 0.18 b* = +10.85 [+ or -] 0.14 Ink: Ink: L* = 63.87 [+ or -] 1.63 L* = 69.34 [+ or -] 1.25 a* = +1.05 [+ or -] 0.82 a* = +3.02 [+ or -] 0.89 b* = +14.66 [+ or -] 0.54 b* = +13.52 [+ or -] 1.24 TABLE 2: Treatments of laboratory paper samples with calcium propanoate in ethanol.
According to this claim and the graph of the variables (Figure 4), the compound mainly responsible for differentiation (axis 1) is 1-methylbutyl propanoate. In regard to the axis 2, the compound is more akin to decanoic acid.
Salmon  claims that when two yeasts grow and ferment in the same medium simultaneously, exchanges of metabolites among them can take place, causing sensitive modifications to kinetic properties of each of the strains, and also can cause significant changes to the end products of fermentations; that is, interactions can increase the concentration of aromatic compounds and/or make new compounds form, which is consistent with the finding in this study, as it has increased production of 1-methylbutyl propanoate and decanoic acid as shown in Table 5.
According to the PCA variable selection, the main compounds that differ in the treatments in mixed culture, where the ICV K1 and T306 strains are involved, are 1-methylbutyl propanoate, 3-methylbutyl-3-methylbutanoate, 3-phenyl-2-propenal, (E)-4-[(5R)-5,6,6-trimethylcyclohexene-1-yl]but-3-en-2-one, and ethyl laurate.
 and to Figure 6, we can say that axis 3 has more relation with the compound 1-methylbutyl propanoate, with a variance of 5.8%.
In this case, according to PCA, seven are the compounds that differ in the treatments: 3-methyl-1-butanol, 3methylbutyl propanoate, 3,7-dimethyl-2,6-octadien-1-ol, 3-methylbutyl butanoate, 3-methylbutyl-3-methylbutanoate, 3-phenyl-2-propenal, and dodecanoic acid.