1. (a) In order to compute the ratio of soluble solids to acid, the equipment necessary is as follows:

   1. (1) 10 c.c. pipettes
   2. (2) 250 c.c. Erlenmeyer flasks
   3. (3) 100 c.c. graduated cylinder

   4. (4) Bottle for indicator--1 oz. capacity

      The additional necessary supplies are phenolphthalein indicator solution and sodium hydroxide standardized so that 1 c.c. is equivalent to 0.01 gram tartaric acid.

2. (b) Procedure for making the soluble solids to acid ratio test:

   1. (1) The soluble solids content of the juice of the grapes in the sample is determined in accordance with present practice.
   2. (2) 10 c.c. of the clear juice should be pipetted into the Erlenmeyer flask.
   3. (3) Add up to approximately 100 c.c. of distilled water to the juice in the flask.
   4. (4) Add three to four drops of the indicator solution.
   5. (5) Titrate by the addition of the sodium hydroxide (1 c.c. equivalent to 0.01 gram tartaric acid) until the end point is obtained as evidenced by the first definite color (pink) change.

   6. (6) Calculate the ratio according to the following:

      1. 1. 16.0 soluble solids percentage
      2. 2. 8.0 c.c. of NaOH used
      3. 3. 8.0/10 = 0.80 (acid content)
      4. 4. 16.0/0.80 = 20 (ratio)

      (Sodium hydroxide used)/10 = acid content

      (Soluble solids percentage)/(acid content) = ratio

      An example is given as follows:

Note: Authority cited: Sections 407, 42681 and 42684, Food and Agricultural Code. Reference: Section 42941, Food and Agricultural Code.

History

1. New Sections 1427 through 1430 filed 7-7-55; effective thirtieth day thereafter (Register 55, No. 10).

2. Renumbering from Section 1427 filed 1-21-75; effective thirtieth day thereafter (Register 75, No. 4).

3. Amendment filed 7-18-83; effective upon filing pursuant to Government Code Section 11346.2(d) (Register 83, No. 30).