THE ANALYST 183 A CONTRIBUTION TO A KNOWLEDGE OF THE CHEMISTRY OF CIDER. BY ALFRED H. ALLEN. (Read at the Meeting, December 11, 1901.) CIDER is well known to be prepared by the alcoholic fermentation of apple-juice. Skilful manufacturers maintain that the juice itself is all that is needed for the production of a perfect article, the processes being of the simplest kind :-namely, the preparation of the juice by pressing the sliced or grated apples; exposure of the juice at a temperature of or near 60" F., when it undergoes spontaneous alcoholic fermentation; and the removal of the dregs and scum, which form in considerable quantity, by racking as often as may be necessary, supplemented in some cases by filtration of the liquid. Sometimes catechu or other tannin matter is employed to precipitate albuminous matters, occasionally anti-acids are used to correct undue acidity, and preservatives, especially salicylic and boric acids, are stated to be frequently employed.An extensively-advertised preservative of cider, which I purchased in Bristol, was found on analysis to consist of calcium sulphite. According to Mr. G. Embrey, in Gloucestershire, an addition of 1 quart of milk to 18 gallons of cider is often made for fining the liquid, and as a preservative salicylic acid is frequently used in a proportion of 1 ounce to 96 gallons. The apples suitable for the manufacture of cider are in many cases grown especially for the purpose, and are somewhat unpalatable, as they contain con- siderably more tannin than ordinary table apples. Ordinary table apples are unsuited for the production of cider, and, in fact, but few varieties of apple can be advantageously used alone, the practice of skilled cider-makers being to employ a mixture of different kinds of apple, so that the excess of certain constituents in some kinds may compensate for the deficiency in others.Among the most esteemed cider-apples of the South-west and West of England are the Fox Whelp, Roya.1 Wilding, Sweet Alfred, White Normandy Beech, Tom Put, White and Yellow Styres, Handsome Mandy, Kingstone Black, and Skyrme's Kernel. In America, cider is made from the Baldwin, Newtown Pippin, Sweet Vandever, Rosebery Russet, Rambo, and many other varieties of apple, some of which are ill- suited for the purpose. There is no doubt that in some parts of England the apple-trees have been so neglected that their fruit has degenerated, and contains an abnormal proportion of acid.The trees in some districts are rarely, if ever, pruned or manured, and the apples-windfalls,, ripe and rotten fruit together-are allowed to remain in the orchard for many weeks, in some cases not even being stacked or protected from pollution by animal excreta. Starting with a mixture of unripe and more or less damaged fruit, with possible admixture of foreign matters, it is not surprising that the cider made and consumed by the rural population of the cider districts is apt to be of very inferior quality. The manufacturers of cider for public sale, of course,184 THE ANALYST. Water . . . ... ... 1 81.62 84.74 { 80.29 Free acid (as malic) .. . I 0.88 0.56 0.097 Glucose.. . ... . . + I ’ 9.28 8.75 ’ 9.43 Sucrose.. . ... j 6-28 2.29 1 2.95 proceed in a more systematic manner, but they are largely dependent on the defective fruit described above. Cider is, however, now manufactured in England in increasing quantities under conditions in which the above defects are carefully guarded against, and a product of unexceptionable quality results. Opinions as to the effect of apple-pips on the quality of cider vary greatly. Some cider manufacturers aim at crushing them, while others as carefully avoid doing so. It is not generally recognised that under the generic term ‘‘ cider ” are grouped a number of products of the fermentation of apple-juice, which products vary among themselves almost as greatly as the numerous products from the fermentation of grape-juice grouped together under the generic name of ‘‘ wine.” Yet no distinctive names are given to the different classes of cider, except such as “sweet,” dry,” L c sparkling,” etc.The geographical origin allows of some differentiation in the character of cider, but the terms ‘ I Devonshire,” ‘‘ Herefordshire,” American,” etc., have not the same definite meaning that attach to the names Burgundy, Bordeaux, Champagne, Port, etc., in the case of wine. The proportion of sugar varies in cider from 10 to less than 1 per cent., diminishing with the age, while the proportion of alcohol increases. A serious practical difficulty in the classification of cider is its tendency to undergo both alcoholic and acetic fermentation in addition to more obscure changes, so that it is very difficult to insure that any particular brand shall be of approximately constant character.I n the case of sweet cider, which is necessarily only partly fermented, the proportion of alcohol is generally too low to preserve tho liquid from further change, and hence a foreign antiseptic agent, such as salicylic or boric acid, is sometimes added. A “ d r y ” cider, in which more perfect fermentation has occurred, is t 3 be preferred on several grounds, but the manufacture of a natural product of this kind presents considerable difficulties, and the demand for it is limited. As long as the cider contains a fair proportion of sugar the sweet taste masks the presence of any excess of acid, but in dry cider this becomes unpleasantly apparent, unless some supplementary treabment be adopted.The following table shows the chief constituents of appEes analysed in my laboratory : 84-14 0-36 7-21 2.84 TABLE I. I Sweet Derby. 1 Alfred. I Tom Put. I ’ Blenheim I Orange. ITHE ANALYST. 185 ___ 1098.0 25-32 0.24 6.14 20.99 1.8 0.32 Many published analyses of apples and apple-juice are misleading, owing to the observers having ignored the presence of non-reducing sugars. Such sugar (presumably sucrose) is always present, and sometimes in considerable proportion. When the fruit is over-ripe the proportion of sucrose diminishes, a portion of it undergoing inversion, though part apparently undergoes a less simple change. The following figures, obtained in my laboratory, show the change resulting from decay in the case of two typical Devonshire cider-apples.The decayed portions were carefully separated from the still sound parts of the fruits, and eacb fraction analysed separately. Moisture ... ... ... ... 80.50 81.68 Volatile acid ... ... ... 0.016 Fixed acid ... ... ... ... 0.109 0.436 Sucrose (non-reducing sugar) ... 6.67 1.49 4.74 0.98 The composition of the pressed apple-pulp, or marc, obtained in large Devonshire cider factories is shown by the following figures. In the cases of the first three samples the apples had been pressed once only, but in the case of the fourth the pulp had been broken up and re-pressed : No. 1 APPLE. No. 2 APPLE. Sound Part. Decayed Part. Sound Part. Decayed Part. - - 0.057 -- - - I Glucose (reducing sugar) ...9.30 11.86 9.49 11.61 1 2 3 4 Moisture ... ... ... 68.14 68-14 75-62 63.36 Glucose ... ... ... 4.04 - 4.69 2.24 Sucrose ... ... ... 2.14 - 2.26 1 -88 Ash ... ... ... ... - 1-01 1.03 1.71 The large proportion of water in apple-marc renders any useful application of the product very difficult. To a limited extent, and when quite fresh, it is sometimes employed as a cattle food, in other instances it is burnt under boilers fitted with EL special contrivance, and in other cases it is taken out to sea. The following table shows the variation (grammes per 100 c.c.) in the chief constituents of appk and pear juice from various parts of France, as recorded by Truelle : TABLE 11. 1084.5 21-95 0.15 3.67 14.56 1.31 0.18 I APPLE MUST. 1, PEAR MUST./I I I I Minimum. Maximum. 1 Average. I Minimum. I I I t Specific gravity ... /1057*5 I 1110.0 Acidity (as H,SO,) ... i 0.07 1 0.74 Sucrose ... . . . . 0.56 1 7.17 Glucose ... ... l 10.84 j 18.18 Pectous and albumin- j I 28.57 I Total solids calculated from specific gravity 14.94 1 1 I ous matters ... ' _ ' 2.3 Tannin ... ... 1 0.026 j 0.81 1076.0 '1 1067.5 I 0.21 0.08 2.50 1.67 13.58 1 10.81 1.2 0.3 0.29 0.10 Maximum. ~ Average.186 THE ANALYST. The following results show the composition of fresh apple-jaice as used for the manufacture of cider in the South-west of England. The formation of alcohol occurs very rapidly, and hence a notable proportion was found in several cases, though the analysis was commenced within thirty-six hours of the apples being pressed.TABLE 111. ~ - 1 A. _ -- Specific gravity ... ... j 1.0550 Alcohol, present by weight ... 0.10 Total extractive matters ... 14.63 Glucose ... ... ... (13.51) Sucrose ... ... ... ... 1-34 Fixed acid (as malic) ... ... 0 28 Ash ... ... ... 0.35 Tannin .. ... ..* Original solids ... ... ... , 14-84 ... ... 1 - I B. 1.0530 - 12-74 10.48 0.69 0.42 0.30 0.22 12-74 C. - _I 16-11 12.50 0.1 2 - -- I E. =. , 1.0470 1.04 11.91 9.13 0.66 0.45 0.22 1.0470 1.13 11.95 8.82 0.38 0.50 0.26 0.11 : - , 1 - I I 16.11 14.05 1 14.28 ~ _ _ _ _ _ _ The next three tables show the results yielded by the analysis in my laboratory of typical English ciders. TABLE IV. AnaZysis of Six Varieties of Norfolk Bottled Cider. I I D. E. I 1 - - - _. I - . Specific gravity .... I 1.012 1.012 I I I Alcohol, by weight _..= Proof spirit ... .Total extractive Glucose ... Fixed acid (as malic) Volatile acid (ii acetic) ... i .Ash ... ... i matters ... l 5.30 7.21 1.60 15-72 2.07 2.54 0.77 1.16 0.35 0.42 0.07 1 0.21 0.30 0.26 Original solids ... 13.09 17.71 F. 6.56 ' 7.29 ' 7.14 14.34 ~ 15.88 j 15.57 I ~ I 4.55 I 4.71 5.47 4.16 1 4.55 1 3.12 I 0.39 1 0.42 0.41 , 0.31 0.15 0.11 0.10 0.10 0.31 1 0.33 , 0.27 , 0.26 I 8 I 18.45 i 20.65 I 19.41 , 18.32 1.002 7.69 16.73 2.33 0.88 _ _ _ _ _ _ __I___-THE ANALYST. 187 TABLE V. Analysis of Typical Samples of Devonshire Bottled Cider. H. ' I. .--- 1.003 1.013 J. I K. L. M.* N." -1 ---__-I--/ ,-I-_ I--- I 1.006 ~ 1.032 ' 1.011 1.029 1.0275 1 1.0230 ' 1.0260 1 1.0190 _- 1.012 4.77 10.411 4-09 2.94 0.15 0 -19 0'23 -- Specific gravity Alcohol, per c e n t .b y weight . . . = Proof spirit Total extrac- tive matters Glucose ... Fixed acid (as malic) ... Volatile acid (as acetic) .. . Ash ... ... 5.39 5.09 11.79 11-14 4-95 2-57 , 4 09 10.82 5-63 ~ 8.96 4-01 3.77 8-79 8'28 7-77 ' 7.93 6.76 6.85 0.30 0.33 0'30 0-23 0.27 0-2.5 4.1 8 9-16 7-13 5-62 0.35 0 2 4 0'31 16.10 6 -2.5 3.43 7 -53 7 '73 5.68 0.34 0.20 0.41 15.10 6.76 4'62 10.13 6.25 4.90 0'22 0'28 0.36 16-19 5-10 8.23 3.88 7.24 2.17 0.31 , 0.21 0-37 0.31 0'34 0.30 I 2-80 4.27 j 2-12 1'43 2.27 0*9& 0.19 0.33 ~ 0'12 0-29 0'34 0.25 0.32 0.24 0.20 Original solids 1 14-20 Total sugar (as ' glucose) ... - 14.39 15.12 112.62 14.08 12.77 16-48 16'05 ~ ~ I __ ~ - - * A small quantity of sugar solution was added to these ciders.TABLE vr. Analysis of English Draught Czders of Good Quality. T. 1.027 3.86 U. V. 1.016 1.006 - - __. I 4-06 4-37 R. ' s. ' ~ ___ ~~ '-_-- Specific gravity . . . - 1.012 I 1 w. 1.028 __ - 2-49 5-47 7-52 6.17 0.20 0-23 0.24 12-99 Alcohol, per cent. by weight ... ... = Proof spirit ... 5.86 12.83 3-96 8-68 3.04 - 0.43 0.18 0.22 11-47 8-47 8.90 9-58 Totd extractive 1 matters ... I 7.63 2.59 0.93 8.14 4.17 1 2.94 Glucose Sucrose Fixed acid rnalic) Volatile acid acetic) - 0.41 0.21 0.31 ~ 0-25 0.26 0.16 0.34 16.39 0.18 I 0.20 0.24 , 0 35 I \Ash .I. ... 0.22 13.81 1 11.89 Original solids ... 20.01 -188 THE ANALYST. The following is an epitome of an elaborate research on the composition of French ciders by Eugene Grignon (Le Cidre, Paris, 1887). The figures for alcohol are given in C.C.per 100 C.C. of cider, but the other figures (given originally in grammes per litre) are expressed in grammes per 100 C.C. of the cider. The samples in Columns A and C, were made from pure apple-juice, without any addition of water. Samples in Columns B and D were ciders to which known proportions of water had been added, and were consumed in the districts in which they were produced; but the figures in the table are corrected for the water added, and so represent undiluted ciders. renourris ” ciders from the Depart- ment of the Eure. These are ciders five or six years old, which have received annually an addition of must sufficient to make up for the loss by evaporation. They are relatively rich in alcohol and low in extractive matters, the pectous bodies undergoing gradual precipitation.To the actual results of analysis, Grignon appends the calculated amounts of alcohol and extractive matter which would be found in the cider if it had undergone complete fermentation. This is effected by deducting 0.1 per cent. from the sugar found by analysis (as an allowance for matters other than sugar which reduce alkaline copper solution, and are not removed by a preliminary treatment with basic lead acetate), and multiplying the difference by 0.6117, on the ground that 100 grammes of invert sugar yield on fermentation 61.17 C.C. \ == 48.55 grammes) of alcohol. Thus, if a sweet cider contain 4.0 per cent. of alcohol (by volume) with 6.64 grammes per 100 C.C. of total extract, including 3.57 of sugar, then the completely fermented liquid will contain 6.12 C.C.of alcohol and 3.17 grammes of extract per 100 c.c.::: An additional allowance might advantageously be made for the acetic acid present in sour cider. Each gramme of this corresponds very nearly to 1 C.C. of alcohol. The free acid of the cider is stated by Grignon in terms of sulphuric acid, instead of the fixed acid being calculated as malic and the volatile acid as acetic acid. One C.C. of normal alkali will neutralize 49 milligrammes of H3S04, 60 of HC,H,O,, or 67 of HgC4H406, so that no large error results from the fact that the fixed and volatile acids are not differentiated. In the following tables I have added to Grignon’s figures a statement of the original solids of the juice, but in calculating them I have made a constant allowance of 0.2 per cent.for sugar lost from the extract through acetic fermentation. Column E shows the composition of * 3.57 of sugar found, minus 0.10, leaves 3.47 of corrected sugar i n sample. 6.64 of extract, niinus 3947, leaves 3-17 extract in the completely fermented cider. 3.47 of corrected sugar, multiplied by 0.6117, gives 2.12 increase in alcohol, which, added to 4.00 in original sample, gives 6-12 C.C. of alcohol per 100 C.C. of completely-fermented cider.THE ANALYST. 189 TABLE VII. Analyses of French Ciders (E. cfrig'12on). _ _ - - a. Sweet Sparkling. - -- .- Number of samples contributing to average . _ . ... ... ... 5 Alcohol (by volume) ... ... ... 3.8 Extract (dried at looo C.) .._ ... 6-41 Ash ... -.. ... ... 0.29 Acidity (as HiSO,) .. . . . . ... 0.36 Sugar ... ... ... ... ... 3-47 Polarimetric indication ... ... - l"11' Alcohol after complete fermentation 5.9 Extract ,, 9 ) ,? 3-04 I Original solids of juice (Allen) ... ! 12-77 Is. C. Sweet. Dry. 4 4.1 6.40 0.28 0-39 3.75 - 6.3 2-74 13-24 30 5.4 3-03 0-27 0.52 0.65 - 0" 12' 5.8 2-48 11.97 ~ .~ - D. Dry. -- 15 5.4 2-95 0-26 0.58 0.58 -0" 04' 5-7 2.47 11.90 - E. Renourri. __- l o 7.0 2.22 0.24 0-54 0.27 - 0" 02' 7-1 2-05 13.76 The following figures show the extreme and mean composition of the sixty-four eiders included in the above table : TABLE VIII. Minimum. 1 Maximum. Average. ~ ~~ _. _ _ - Alcohol (by volume) after complete fermentation Ash ... ... ... ... 0.17 3.8 Extract, after complete fermentation -. . ... 1-71 Original solids of juice ...... ... ... Acidity (as H2S04)" . . . ... ... 0.27 - - _ - - ~ _ _ _ _ - ... - __ 8.0 6.0 4.50 2.47 0.35 , 0.27 0.71 0-52 - 12.39 --____-___-- The sample containing only 1-71 of extract was a renourri cider. In the greater number of cases the extract was considerably higher. The ash was usually notably higher than 0.17, the sample yielding this exceptionally small proportion showing 6.3 of alcohol (calculated) after complete fermentation. The following figures show the average composition of pure ciders from various parts of France analysed in the Paris Municipal Laboratory : TABLE IX. Alcohol, per cent. by volume ... .., ... Solids, grammes per 100 C.C. ... ... ... Sugar $ 9 ... ... Ash 8 ) .. ... ... ) 9 ) ) ... Well-fermented Cider.5.2 4.12 0.89 0.29 Sweet Cider. 1.7 6.69 2.91 0.26190 THE ANALYST. From these results the Paris authorities ruled that pure, well-fermented ciders of the ordinary type should contain : Average. ... Alcohol, per cent. by volume ... ... 5 to 6 Extract, grammes per 100 C.C. ... ... ... ~ 3.0 ... Ash . . . . . . 0.28 9 ) 9 1 Minimum. 3.0 1.8 ~ 0.17 ~~ Analyses of ciders from various parts of France, by G. Lechartier (Compt. rend., ciii., 1104) show considerable departure from the foregoing figures. It must be borne in mind that low alcoholic strength implies a high extract, so that the figures representing the minimum limits will never be met with in the same cider. Perry presents a very close general resemblance to cider, but has a sweeter taste. This is not due so much to a larger proportion of sugar as to the smaller proportion of malic acid, the presence of which in cider masks the taste of the sugar.Pears usually contain very little acid, but are often rich in tannin and mucilaginous matters ; and hence the fermented product is more difficult to deal with than one prepared from a mixture of apples with pears called in France cidresse. Pears intended for the pro- duction of perry should be aromatic, rich in sugar and tcnnin, moderately acid, and at the exact point of ripeness. A large portion of the perry produced in France is distilled for the production of spirit. The following analyses of sparkling pers-y from Worcestershire and Devonshire were made in my laboratory. The analysis of Gloucestershire perry is by Mr.G. Embrey : TABLE X. Specific gravity ... ... ... Alcohol, per cent. by weight ... = Proof spirit per cent. ... ... Total solids ... ... Glucose ... ... ... . . . Sucrose .. . . . . . . ... Ash ... Volatile acid (as acetic) ... Fixed acid (as malic) .. ... ... ... . . . Original solids ... ... . . . Worcestershire. 1020.0 4.61 10-11 6.51 0.41 0.25 2.71 0.40 16.61 none Devonshire. 1021.0 4.81 10.54 6-49 0.35 0.20 3.60 0.31 0.28 16.92 Gloucestershire. 1010.0 3.64 7-98 4-50 0.22 0.24 0.36 0.30 12.33 - With regard to the sophistications of cider, by far the most usual is dilution with water either before or after fermentation. How far it is legitimate to treat the once- pressed marc with water, and, after again pressing, to add the washing so obtained to the pure juice, is open to question.TEE ANALYST.191 Tartaric and citric acid are sometimes added to cure diseases of cider, and in other instances preservatives are used. m7ith regard to preservatives, I may say that in English ciders made by large manufacturers I have not met with any salicylic acid, though it is said to be commonly used in cider of American origin. Another preservative said to be largely employed by cider manufacturers is boric acid. At the commencement of the investigation on which this paper is founded I found boric acid in every sample of cider I examined, and naturally supposed its use as a preservative to be very general ; but an examination of the apples themselves showed that boric acid was a constituent of apples to such an extent as to be very misleading, if the fact of its natural presence were ignored.As it is, a very strong reaction with turmeric is obtainable from 20 grammes of cider, apple-juice, or from the fruit itself. Of course, boric acid has been recognised as a natural constituent in minute quantity in various plants. Thus, it has been found in all parts of the vine and in hops, but not in malt or barley. Gassend found it in grapes, apples, and in some pears, but not in all; and he states that it is absent from tea, saffron, and cows’ milk. Hodder found it in fruits generally, Crampton denies its presence in apples or cider, while Jay states that cider and perry contain from 0.011 to 0.017 gramme per litre. A considerable number of experiments on the presence of boric acid in apples and other fruit have been made in my laboratory by Mr.A. R. Tankard, who found it in all the apples examined, and also in pears, quinces, pomegranates and grapes. I n a specimen of (‘ Fox Whelp ” apple the amount of boric acid was 0.0076 per cent. ; in quince half as much again, Considerable trouble has been taken to arrive at a satisfactory method of deter- mining these small quantities of boric acid in the presence of excess of phosphates, etc., and a satisfactory process was only devised after a large number of experiments had been made. The process actually employed must form the subject of a subsequent paper. Dilution of cider will generally be indicated by deficiency in the proportions of alcohol and extractive matters. This can be calculated by the method of Grignon already described, but an alternative and preferable plan is to calculate the original solids of the juice from the results of the analysis, thus : I n pears the proportion appears to be variable.Alcohol, per cent. by weight x 2.07 = sugar fermented . . . Acetic acid found x 1.5 = sugar fermented . . . Extractive matter in sample ... . I . ... ... . . . ... Sum = original solids of juice . . . ... ... - The original solids of unwatered cider when thus calculated rarely fall below 12 per cent. On the other hand, an excessive proportion of original solids points to an addition of saccharine matter. A valuable corroboration of the deduction from the foregoing method is obtained by a determination of the ash of the cider. According to G. Erubrey, this should range from 0.25 to 0-35 per cent., and should not fall below the former figure. In American ciders a larger proportion of ash is usually met with, but for French ciders the limit of 0.25 per cent, would be too high. The addition of mineral matters such192 THE ANALYST. as alkaline carbonates, lime, or boric acid would tend to increase the ash, and thereby invalidate the inference. In 1895, as a result of a careful investigation and consultation with the Pomo- logical Society of France, the Bath and West and Southern Counties Society recom- mended that no cider should be considered genuine which did not contain at least 4 per cent of alcohol by volume ( = ? per cent. of proof spirit). This provision is insufficient unless supplemented by a requirement as to sugar or extractive matter. Incompletely fermented (sweet) cider of excellent quality might readily fail to comply with the foregoing requirement,* although by fermentation of the residual sugar the matured product would contain nearer 6 than 4 per cent. of alcohol. I have t o acknowledge the valuable assistance received from Mr. Jas. Thompson and Mr. A. R. Tankard in the execution of the greater number of the numerous analyses made in connection with the enquiry.