UNTERSUCHUNGEN ÜBER PECTINSTOFFE.
R. W. Tromp de Haas and B. Tollens (Lieb. Ann., 286, 278).
ÜBER DIE CONSTITUTION DER PECTINSTOFFE, B. Tollens (ibid. 292).
INVESTIGATIONS OF PECTINS.
(p. 216) It is generally held that the pectins are, or contain, oxidised derivatives of the carbohydrates. The authors have isolated and analysed a series of these products, and the results fail to confirm a high ratio O : H. The following are the analytical numbers:
| Pectin from | Ash | C | H | Ratio H : O |
| Apple | 6.2 | 43.4 | 6.4 | 1 : 7.9 |
| Cherry | 20.5 | 42.5 | 6.5 | 1 : 7.9 |
| Rhubarb | 4.2 | 43.3 | 6.8 | 1 : 7.4 |
| Currant | 5.0 | 47.1 | 5.9 | 1 : 8.5 |
| Greengage | 3.3 | 43.0 | 5.9 | 1 : 8.5 |
| Turnip | 7.3 | 41.0 | 5.9 | 1 : 9.0 |
Acid hydrolysis (4 p.ct. H2SO4) gave syrupy products not crystallisable—in certain cases the hydrolysis was accompanied by separation of insoluble cellulose. The insoluble product from currant pectin had the composition C 54.4, H 5.0.
Tollens points out that the results of empirical analysis are inconclusive; and that from the acid reactions of these products and their combination with bases, carboxylic groups are present, though probably in anhydride or ester form.
The pectins may be regarded as closely related to the mucilages (Pflanzenschleim), differing from them only by the presence of the oxidised groups in question.