Biochemical Studies on^|^ldquo;Miso^|^rdquo;, Fermented Soy-been Paste. Part IV

(1) The content of cystine in various kinds of“Miso” in polished rice, and in soy-beans was determined by Y. Okuda's or by Folin-Looney's method, and whether or not, the amount of cystine in the polished rice diet supplemented with“Miso” was sufficient for the growth of white rats was investigated in connection with the excretion of a cystine complex in the urine.(2) It was found that cystine in“Miso” can be easily decolorized and determined by Okuda's method, after hydrolysing it with concentrated HCl for 12-20 hours. Consequently, the amount of cystine in 100g of the fresh “Miso” was as follows: “Shiromisu” 64.2, “Yedomiso” 45.4, “Sendaimiso” 50.9, and “Hatchomiso” 93.4mg(3) The amount of cystine estimated by Folin-Looney's method was slightly larger than the above, asuming“Shiromiso” 67.2, “Yedomiso” 85.6, “Sendaimiso” 86.6, and “Hatchomiso” 103.2mg.(4) The c3rstine content in 100g of polished rice was 37.8-55.2mg by Okuda's method.(5) From the above, the amount of cystine in 100g of“Miso” diet was calculated to be 0.062-0.065g and cansequently is very slightly defficient in cystine for the growth of white rats, since the diet contains 0.57% cystine for the diet protein.(6) It was pointed out that the cystine value of the urine, kidneys and livers of the cystine-fed animals were greater than those of the control diet animal, and that the value were probably proportional to the cystine administration. The animal fed on 0.1% cystine diet was approximately normal. The excretion of cystine by the animal placed on 1.0% cystine diet was 4.5mg per day and was ten times that of the Patrogen fed animal.(7) Folin-Looney's value of the urine excreted by the animal when fed on an excess of cystine, was temporarily influenced by the excess of NaCl but it gradually diminished.