8 THE ANALYEIT. ON THE NITROGENOUS CONSTITUENTS OF COCOA. By G. W. WIQNEB, F.C.S., Read before the Society of Public Analysts, on 20th November, 1878. COCOA has been constantly referred to as one of the most nutritious foods, because of the high proportion of nitrogenous matter contained in it. Payen in the analysis of nibs, free from husk, found 21.2 per cent. of albuminous matters, and Church in the recent guide to the Bethnal Green Food Collection, gives 17 per cent.of albuminous mdtters, as the average of pure roasted cocoa nibs. Heisch examined a number of samples of roasted cocoa beans obtained from different localities, the results of which were published in 2% Analyst; * but in most cases, be found figures considerably lower than these; the highest amount yielded by his samples was 2.06 of nitrogen, corresponding to 13.03 per cent.of albuminous matters, and the lowest was 1-17 per cent. of nitrogen, corresponding to 7.40 per cent. of albuminous matters. All these determinations appear to have been made by the estimation of nitrogen by the soda lime process, and the calculation of the albuminoids from the total nitrogen found. The recent investigations of Church and others on the form in which the nitrogenous matters exist in roots and cereals, and my own recently published investigations on the nitrogen compounds present in the cereals, led me to think, that the nutritive quality of cocoa might possibly have been somewhat over estimated, owing to the non-separation of the coagulable from the non-coagulable albuminoids.This process gives us two determin- ations, one of the total nitrogen, and one of the coagulable nitrogen, both subject, of course, to the errors due to the soda lime process. The latter determination, viz., coagulable nitrogen, is the only one, which in the present state of our knowledge, we are justified in assuming as really flesh forming matter, since it is this only which can be classed aa true albuminoid matter.The non-coagulable nitrogen may, and part of it unquestionably does exist in the forms of nitrates and nitrites, and another part exists in the form of alkaloids, and at preaent, we have nothing to prove that either of these are properly classed as flesh formers. I f therefore, this proportion of non-coagulable nitrogen is found to beehigh in any food, it follows, that we must consider its nutritive value as being so much lower than had been hitherto supposed when the calculation was made from the total nitrogen. Now in the cases of wheat, barley and oats, I find that various proportions, aometimes as much as 35 per cent.of the total nitrogen, are in non-coagulable forms, and on extending this enquiry to cocoa, I find that the percentage of the total nitrogen so present is in many cases higher than even these figures. I hare, of course, been able to examine only a limited number of samples, and therefore, I have selected six ordinary commercial samples, and four samples of entire cocoa beans.The commercial samples are practically certain to be admixtures of different varieties of cocoa, and therefore, in a case like this they will give a more correct general impression than selected samples of special varieties.It is true that most of the commercial samples contain an admixture of either starch or flour, but by bearing in mind that average flour contains about 90 per cent. of its nitrogen in a ooagulable form, it is eaery t o make the allowance for this admixture.* Vot l., p. 142.THE ANALYST, 9 I am indebted to Mr, Heisch for the four samples of roasted beans. The following are the results obtained :- The determin- ations in these cases have been made on the entire bean, the hutik not being removed. Mark. A B C D E F Socunza Para Trinidad Grenada 1.095 1,162 2.978 -965 -699 1.201 2-040 20000 1.490 2.310 '600 -760 2.335 -375 -330 .770 1.175 1,045 1.050 1.335 6.92 7.35 18.84 6.1 1 4-42 7-6 1 12-92 12.67 9.46 14.99 NITROGENOUS MATTERS IN ORIGINAL SAMPLES.Totai Coagulable Difference = Total N. Coagulable albuminoids albuminoida r\'on-coaguldble N. =N X 6.33 = N X 6.33 nitrogenous matter. 3.80 3.12 4.8 1 2.54 14.79 4.05 2.37 3.74 2.09 2.33 4-88 2-78 7.44 4.48 6.62 6.05 6-65 2.8 1 7.66 7.43 per cent.Total N. coagulable. 54.9 65.5 78-5 38.8 47 3 64.1 57.6 52.2 70-3 50.4 It thus appeare, that even the very o the samples, 2i.5 per cent. of the nitrogenous matter present is in a non-coagulable form, and cannnot, therefore, in the present state of our knowledge be recognized as of value as a flesh former. While in the case of the prepared cocoas, the proportion present as true gluten falls in one case to 39 per cent. of the total quantity, and in the case of one of the entire cocoa beans to about half of the total found by the ordinary combustion. The average of the entire beans being 57.6 per cent. of the nitrogen in the coagulable form. Until the nutritive value of non-coagulable albuminoids is proved, cocoa must therefore rank far lower in the scale of foods than it has done hitherto.