Points in Making Cider

New Zealand Journal of Agriculture, Volume 63, Issue 2, 15 August 1941, Page 149

Points in Making Cider

Viticulture

Determination of Soil Acidity

A SAMPLE of 25 c.c. of the cider is heated to the start of ebullition to expel any carbon dioxide gas, and titrated while hot with decinormal (N/10) sodium hydroxide, using 5 per cent, phenolphthalein as indicator. The results are expressed in terms of malic acid—l c.c. of N/10 alkali = 0.0067 grams of malic. If the cider has definitely no gas in it, it is not necessary to heat the sample.

Equipment Required

(1) 1 x 50 c.c. burette, graduated in tenths of a cubic centimetre. The burette is fitted either with a glass top or a rubber jet and clip. (2) 1 burette stand, either of wood or iron. (3) 1 x 25 c.c. pipette. (4) 1 x 200 c.c. glass beaker. (5) Ix 4 ozs. of 5 per cent, solution of phenolphthalein. (6) 1 glass stirring rod. All the above equipment is obtainable from wholesale druggists and scientific instrument dealers.

Method. — By means of the pipette, place 25 c.c. of the sample to be tested in the beaker and heat to near boiling (175 deg. F.) to drive off any gas. Allow it to cool slightly, add 2 drops of the 5 per cent, phenolphthalein, and place under burette which has been filled to the zero mark with the N/10 solution. Allow the solution to drip slowly into the cider, stirring well all the time with the glass rod. soon as a pink tinge persisting for at least 30 seconds appears, close burette tap and read off the volume of N/10 solution used. Every 1 c.c. of N/10 solution used = 0.0067 grams of malic acid.

D etermination of Alcoholic Content

The alcoholic ’ content is determined by the ebullioscope,, which consists of the-following parts: (1) The boiler into which the distilled water or the cider is introduced. (2) The condenser, which screws on to the boiler. (3) A thermometer which registers the temperature in l/10ths of a degree Centigrade, but enables it to be estimated to within l/100th of a degree. (4) A spirit burner. (5) A slid-

ing scale by which the alcoholic strength of the cider is ascertained. (6) A doubly-marked test tube. The larger volume (50 c.c.) gives the quantity of cider to be used for each test, the smaller volume (15 c.c.) the, quantity of distilled water in which the boiling point is determined. Rinse ' the boiler with distilled water before use. Close the lower stopcock and introduce 15 c.c. of distilled water into the boiler. Screw on the top condenser and fix the thermometer in place. Do not at this stage put any water in the condenser. Place the lighted lamp so that the flame is directly under the chimney. As soon as the temperature on the thermometer remains constant, ■ it is noted and the sliding scale adjusted so that the temperature at which the water boils (given on the middle por- ' tion of the scale) is exactly opposite zero on the outer side of the scale. Turn the screw on the scale to keep it locked in position. The boiling point of the water need not be determined for every test; it is sufficient to do this once in the morning and once in the afternoon, provided, of course, that

no large rise or drop occurs in barometric pressure during those periods. Once the boiling point of the water is found and the scale adjusted, the water is poured from the boiler and the boiler is rinsed out a few times with small quantities of the cider that is to be tested. The stopcock is then closed, and 50 c.c. of the cider are placed in the boiler; the condenser is filled with water and screwed on, and the thermometer is put in place, first making sure that the mercury has returned to place. The spirit flame is replaced to its previous position, and the cider is boiled. As soon as the mercury is stationary it is read off and the flame extinguished.

Refer to the scale, and opposite the boiling point of the cider (given on the middle portion) its alcoholic 'strength will be found, given in degrees of alcohol by volume, which has to be multiplied by 1.75 to give the percentage of proof spirit contained in it. In the case of apple wines where the alcoholic strength exceeds 12 degrees by volume, the wine should be diluted half and half with distilled water before testing, and the. result when determined is then multiplied by two to give the correct results. (To be continued.)

-B. W. LINDEMAN,

Vine and

Wine Instructor, Auckland.