INDUSTRIAL AND ENGINEERING CHEMISTRY
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in the root, i t is seen that the chemical determination of rotenone will give no definite measure of how toxic t h e various preparations made from the root will be when fed.
the extractives is in optically active form, and Fink and Haller (1) have shown that the optically active derivative of deguelin, dihydrodeguelin, is more toxic to mosquito larvae than the corresponding inactive form. Whether or not the variations in apparent rotenone can be associated with changes in t h e optical rotation is not as yet apparent.
Toxic Constituents of Derris Extractives The toxic properties of the acetone extract of derris 2581, when attributed to rotenone, indicate a content of 25 per cent, five times that found by chemical examination. Since it is unlikely that a substance of toxic propertie? equal to rotenone could be present in such amounts and still remain unfound, i t seems more ressonabIe to suppose that there is present one or more substances of much greater pharmacological activity than rotenone, or else that studies based on the crystalline rotenone as isolated do not portray the real danger involved in human ingestion. In this connection Fink and Haller (1) believe that rotenone is probably to be regarded as the most important insecticidal constituent in derris extractives. The other well-characterieed crystalline compounds present (deguelii, tephrosin, and toxicarol) do not in the isolated form possess sufficient toxicity to account for the effectiveness of derris extractives. ?Key point out that, as isolated, only rotenone possesses optical activity. Haller and LaForge (2) have, however, shown indirectly that at least part of the deguelin present in 0
Vinegar from Dates BHAGWAN DAS AND J. L. SARIN Government Industrial Research Laboratory. P. 0. Shahdara Mills, Lahore, India
HE raw material is the fleshy part of the date fruit (PRoeina sylvestria). The ripe fruit is bright red, and the fleshy edible part is 60 per cent of the weight of the fruit. The average percentage composition of the fleshy part is as follows: Moisture Raw fiber Sugars Mineral substances Not specified
20.20 38.53 35.80 2.97 2.50
To secure a rapid and uniform alcoholic fermentation, the fruit is worked into a juice by mixing it with an equal weight of water, boiling for an hour, and pressing. This procedure is repeated three times for maximum extraction. It is then filtered, made to known volume, and analyzed for sugars by standard methods. Although the amount of juice and its Balling degree vary considerably according to the ripeness of the fruit, its quality, extent of fermentation already developed in the fruit, and variety of the fruit, we may expect a yield of juice of about 15" Balling, equal to one and a half times the weight of the fruit. Juice containing 15 to 17 per cent sugar (specific gravity, 13" Balling) is inverted by boiling with hydrochloric acid (1 to 3 cc. per liter) and is then inoculated with a culture by the addition of 0.25 ounce of fresh yeast per gallon of juice to which previously have been added 70 cc. of a solution of nutrient salts (2 grams potassium phosphate, 0.2 calcium phosphate, 0.2 magnesium phosphate, and 10.0 ammonium phosphate dissolved in 860 cc. of water). A good fermentation sets in within 24 hours; the optimum temperature varies from 80" to 90" F. for the reaction which reaches its climax on the seventh day. The absence of reducing sugars indicates the end of fermentation. After the seventh day the Balling measurement is 1" to 2", and the acetic acid content is 0.25 gram per 100 CC. The fermented juice is then subjected t o acetous fermentation in an open vat by the inoculation of pure, young, and vigorous rnycodemza aceti, preferably by the addition of 10 per cent unpasteurieea "mother vinegar" and keeping the mixture still for 2 months. Li ht is excluded from the room as far as possible, since acetic fermentation is inhibited by the direct rays of the
VOL. 28, NO. 7
Acknowledgment The writers are indebted t o H. A. Jones, Division of Insecticide Investigation, and F. L. Campbell, Division of Control Investigations, both of the Bureau of Entomology and Plant Quarantine, for the selection of the samples of derris and cube and permission granted by t h a t bureau to repeat in summary their data.
Literature Cited (1) Fink, D. E., and Haller, H. L., J . Econ. Entomol. (in press). ( 2 ) Haller, H. L., and LaForge, F. B., J. Am. Chem. Soc., 56, 241519 (1934). (3) Jones, H.A., Campbell, F. L., and Sullivan, W. N., J . Econ. Entomol., 28, 285-92 (1935). (4) Lightbody, H. D., and Mathews, J. A., IND. ENCI.CHBIM.,28,
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809 - (1936>. (5) Tatterafield,' F., and Martin, J. T., Ann. Applied Biol., 22, 578-
605 (1935). RECEIVH~D March 26, 1936. .
sun. By the use of special cultures, the loss of acid during acetification can be materially reduced, since it is intimately associated with the life of the microorganism.1 Vinegar, when formed, is pasteurized and stored for some months in air-tight containers for aging. During this long storage period the vinegar deposits albuminous matter, bacterial cells, etc., and undergoes partial clarification.
Clarification Vinegar from inferior-quality dates often becomes cloudy or hazy on standing, which may be due to the presence of colloidal materials, pectin, protein, gums, and tannins. This objectionable property becomes apparent within 30 to 60 days or may be delayed for 12 to 15 months or more. This clouding may occur in both pasteurized and unpasteurized vinegar, in sealed bottles or in those exposed to the air through cotton lugs. This cloudiness is removed more easily by a process o f sedimentation and filtration than by simple filtration; the method employed is chiefly mechanical. Hyflo Filter-Cel (I to 2 per cent) is stirred with the vinegar; as it settles, it carries with it the albuminous particles causing the turbidity. By subsequent filtration under pressure, the sample filters brilliantly clear.
Sterilization After clarification, vinegar still contains acetic bacteria; on exposure to air, the bacteria grow on the surface and make the liquid turbid. Since all acetic bacteria perish at a relatively low temperature, it is sufficient to heat the vinegar to 150' F. by dipping the container in a water bath heated by steam. The vinegar is subsequently cooled by a current of cold water nearly to normal temperature. Sterilization also has the effect of maturing the vinegar and of giving it a softer taste and less acid aroma. This is probably due to its promoting the combination of the residual alcohol in the vinegar with acetic acid and thus accelerating the formation of the ester to which matured vinegar owes its flavor. The final vinegar is clear blackish red in color and smells like wine vinegar. It has a specific gravity of 1.18, a total acid content (as acetic) of 4.98 per cent, traces of ethyl alcohol, 2.17 grams of solids, and 0.17 gram of ash per 100 cc. Twelve to fifteen gallons of standard vinegar are obtained per 100 pounds of fresh fruit. The yield of vinegar from dried or cured fruit is greater because of the greater concentration of sugar. REICH~IVED May 11, 1936. 1 Mitchell, C. A., "Vinegar Manufacture and Examination," London. Charles Griffin t Co.
