▪ I. yeast, n.
(jiːst)
Forms: 1 ᵹist, ȝyst, 5 ȝest(e, ȝeest, yeest, 6–9 yest, 7 eyst (?), 8–9 dial. east, 9 dial. yist, 7– yeast.
[OE. (late WS.) ᵹist, Anglian *ᵹest, corresp. to MLG. gest dregs, dirt, MDu. ghist, Du. gist, gest yeast, MHG. jest, gest, gist (G. gischt, gäscht) yeast, froth, ON. jastr yeast, related to OHG. jeasan, gesan (MHG. jesen, gesen, gern, G. gähren to ferment), the causative OHG. jerian, gerian to cause to ferment, and ON. gerð yeast. The underlying base jes- is found also in Skr. yás(y)ati to seethe, boil, práyastas bubbling over, Zend yah- to boil (intr.), Alb. {gacu}eš buken I knead bread, Gr. ζέω I boil, ζεστός boiled, W. iās seething.]
1. a. A yellowish substance produced as a froth or as a sediment during the alcoholic fermentation of malt worts and other saccharine fluids, and used in the manufacture of beer and to leaven bread.
Modern science distinguishes two kinds of yeast, surface yeast or top yeast (G. oberhefe) and under yeast, sediment yeast, or bottom yeast (G. unterhefe), the former propagated by buds, the latter by spores, of the fungus Saccharomyces cerevisiæ. The yeast of beer is used medicinally as an antiseptic and stimulant in low fevers, and as an application to ulcers.
| c 1000 Sax. Leechd. II. 266 Læt þonne hwon ᵹestandan, do of þa gaᵹellan, do þonne niwne ᵹist. 1530 Palsgr. 291/1 Yest or barme for ale, leueton. 1591 A. W. Bk. Cookrye 8 Put into your broth a spoonfull of yest. 1600 Surflet Country Farm v. xxiii. 725 They renewe the force and strength of the yeast or leuen euerie hower with beere already made, so long as till the said leuen or yeast become strong inough of it selfe. 1612 Househ. Bks. Howard of Naworth (Surtees) 41 To Harry Baker to bestow in eyst vs. 1664 Butler Hud. ii. iii. 119 When Yeast, and outward means do fail, And have no pow'r to work on Ale. 1666 G. Harvey Morb. Angl. viii. (1672) 19 Those sharp scorbutick dregs imitating the nature of yist. 1743 Lond. & Country Brewer iii. (ed. 2) 214 Yeast..consists of a great Quantity of subtile and spirituous Particles, wrapped up in such as are viscid. 1804 Med. Jrnl. XII. 192 An instance of a young gentleman in the last stage of typhus fever, being cured by the use of yeast. 1843 R. J. Graves Syst. Clin. Med. Introd. Lect. 34 Sugar by presence of yest [is made to resolve itself] into alcohol and carbonic acid. 1858 Lewes Sea-side Studies 314 There are two kinds of yeast, or rather two forms of the same plant. The one is called ‘surface’ yeast, the other ‘sediment’ yeast. The former requires a temperature of 70° to 80° Fahrenheit; the latter 32° to 45°. 1877 Huxley Physiogr. 193 The porous texture of bread is due to the presence of bubbles of gas evolved by the fermentation of the yeast. |
b. With qualifying word, as
beer-yeast; applied
esp. to common yeast drained, pressed dry, and made into a cake in order to be kept for a time: see
quots. and
cf. yeast-cake,
-powder (4).
| [1781 T. Henry Acc. Method Pres. Water, etc. 26 The Process for making artificial Yeast. Boil flour and water together to the consistence of treacle... In about two days, such a degree of fermentation will have taken place, as to give the mixture the appearance of yeast.] 1845 E. Acton Mod. Cookery xxviii. 650 German yeast, imported in a solid state, is now much sold in London. 1858 Simmonds Dict. Trade s.v., German yeast is now imported to a considerable extent in a dried form from the Continent. 1878 Chambers's Encycl. s.v. Yeast, Patent Yeast is exactly similar [to German Yeast], but is raised from a wort made purposely from malt and hops. Artificial Yeast is a dough of wheat or other flour, mixed with a small quantity of common yeast, and made into small cakes, which are dried. 1879 Webster Suppl., Press-yeast, the yeasty froth from the surface of a fermenting fluid, washed and pressed into cakes for bakers' use. 1889 Pall Mall Gaz. 1 July 3/3 Patent yeast is either made by the baker himself or is bought from the yeast merchant. It..leaves an unpleasant smell and taste in the bread. |
c. fig. = leaven n. 2 a.
| 1760–72 H. Brooke Fool of Qual. (1809) III. 35 Though liberty has no relation to party.., there is yet a kind of yest observable in its nature, which may be necessary to the fermentation and working up of virtue. 1818 Keats Let. Wks. 1889 III. 105 The best of men have but a portion of good in them—a kind of spiritual yeast in their frames, which creates the ferment of existence. 1873 Dixon Two Queens vi. iv. I. 324 The Plantagenet yeast being strong within his sons. |
d. A fungus that exists predominantly as single cells rather than a mycelium and in which vegetative reproduction takes place by budding or fission.
Now not
usu. regarded as constituting any particular taxon.
| 1899 Allbutt's Syst. Med. VIII. 760 The common saccharomyces or yeast of the scalp. 1906 G. Massee Text-bk. Fungi iii. 275 Symbiotic relationship between yeasts and bacteria is not uncommon. 1922 H. Gwynne-Vaughan Fungi i. 7 Yeasts and filamentous fungi are abundant in woodland soils. 1930 H. M. Fitzpatrick Lower Fungi i. 16 In the lower Ascomycetes the asci are formed without order throughout a mould-like mycelium, or exist as isolated cells as in the yeasts. 1977 R. C. Cooke Fungi, Man & his Environment i. 14 Yeasts appear in the Ascomycetes, Basidiomycetes, and Fungi Imperfecti. This is because the term ‘yeast’ refers to a special mode of growth and does not describe a particular, special assemblage of fungi. 1983 Oxf. Textbk. Med. I. v. 372/2 Candida albicans... It is a saprophytic yeast often found as a commensal in the mouth and gastrointestinal tract and commonly present in the vagina. |
† 2. The froth or ‘head’ of new or fermenting beer.
Obs.| c 1430 Two Cookery-bks. 10 Þen take ȝest of New ale an caste þer-to. c 1440 Promp. Parv. 537/2 Ȝeest, berme, spuma. 1683 Salmon Doron Med. i. 241 Let not the Head, or Yest work over at the bungs. 1716 Gay Trivia ii. 290 When drays bound high, they never cross behind, When bubbling yest is blown by gusts of wind. |
3. transf. Foam or froth, as of troubled water.
| 1611 Shakes. Wint. T. iii. iii. 94 The Shippe boaring the Moone with her maine Mast, and anon swallowed with yest and froth. 1818 Byron Ch. Har. iv. clxxxi, They melt into thy yeast of waves. 1864 Q. Rev. Apr. 311 The dim headlands of new empires which are already looming darkly up out of the yeast of stormy waves. |
4. attrib. and
Comb., as
yeast-ash,
yeast-cell,
yeast-culture,
yeast dumpling,
yeast-fungus,
yeast-germ,
yeast-poultice,
yeast-scum;
yeast-like adj. and
adv.;
yeast-beer, new beer with which a small quantity of fermenting wort has been mixed to make it ‘work’;
yeast-bitten a. (see
quot.);
yeast bread, bread made with yeast (
i.e. ordinary bread);
yeast-budding, a direct budding or germination of spores from other spores as occurring in
Saccharomyces and other fungi;
yeast-cake, (
a) (see 1 b); (
b) a cake made light with yeast;
† yeast-fat, a fermenting-vat;
yeast-plant, any plant of the genus
Saccharomyces,
esp. S. cerevisiæ, which produces fermentation in saccharine fluids;
yeast-powder, the powder of dried yeast (
cf. 1 b); also (
U.S.) baking-powder.
| 1875 Huxley & Martin Elem. Biol. (1877) 6 Pasteur himself used actual *yeast ash. |
| 1829 Art of Brewing (ed. 2) 54/2 (L.U.K.) The gas being too weak to buoy up the now close head of the tun, the yeast might partially or wholly subside, and the ale would become *yeast-bitten; it would receive that disagreeable taste which the head had acquired by too long exposure to the atmospheric air. |
| 1853 Southern Ladies Bk. (New Orleans) I. 130 The chicks in the free states live on *yeast bread. 1945 ABC of Cookery (Ministry of Food) xviii. 67 Nowadays yeast bread is seldom made in the home. |
| 1898 Porter tr. Strasburger's Bot. 350 Such a method of multiplication of conidia by budding is termed *yeast budding, and the conidia are termed yeast conidia. |
| 1795 Sir J. Dalrymple Let. to Admiralty 4, I put in the Wort-cake and *Yeast-cake at his sight. 1855 E. Acton Mod. Cookery (rev. ed.) xxxi. 604 To test bread that has been cut (or yeast-cakes), press down the crumb..with the thumb. 1897 R. M. Stuart Simpkinsville 136 Here, too, had passed pantalet patterns, bits of yeast-cake and preserving-kettles. 1908 McClure's Mag. Feb. 421/2 We are to be the yeast-cake for democracy's dough. 1973 Listener 20 Sept. 377/2 Tea was served by Auntie Golda..thick slices of cinnamon-veined yeast-cake. |
| 1847–9 Todd's Cycl. Anat. IV. i. 101/2 The importance of *yeast-cells in the phenomena of fermentation. 1899 J. Cagney tr. von Jaksch's Clin. Diagn. v. (ed. 4) 200 Yeast-cells (Saccharomycetes) are the commonest form of parasite in the intestinal discharges. |
| 1898 Allbutt's Syst. Med. V. 420 Protein or dead cultures of bacteria, filtered *yeast-cultures. |
| 1747 H. Glasse Cookery ix. 112 *East Dumplings. First make a light Dough..with Flour, Water, Salt, and Yeast. |
| 1367 Priory of Finchale (Surtees) p. lxxviii, j. *yestefatt. |
| 1876 tr. Wagner's Gen. Pathol. 86 The several fermentation or *yeast-fungi. |
| 1867 Edin. Rev. Apr. 395 The fermentation occurs only in presence of the *yeast germs. |
| 1868 Rep. U.S. Comm. Agric. (1869) 277 The..*yeast-like appearance of the decomposing brood. |
| 1857 Henfrey Bot. §813 What is called the ‘*Yeast-plant’ consists of a particular form of the vegetative structure (mycelium) of a Fungus. 1871 Tyndall Fragm. Sci. (1879) II. xii. 257 The brewer deliberately sows the yeast-plant. |
| 1860 Mayne Expos. Lex., Cataplasma Fermenti,..the *yeast poultice, for sloughing and mortification; flour mixed with yeast and heated till it rise. |
| 1795 Sir J. Dalrymple Let. to Admiralty 2 Wort-cake and *Yeast-powder made at the King's breweries. 1857 W. Chandless Visit Salt Lake i. vi. 95 Three boxes of yeast-powder (at thirty cents each) to improve our bread. 1876 Amer. Cycl. XVI. 777 Yeast powders, or baking powders, substitutes for yeast, used in making bread. |
| 1888 Encycl. Brit. XXIV. 602/1 After ten to fourteen days the *yeast-scum on the surface disappears. |
▪ II. yeast, v. rare.
(
jiːst)
[f. prec.] intr. (also
refl.) To ferment; to be covered with froth, as agitated water. Also
fig. and with
up.
ˈyeasting vbl. n. and ppl. a.| 1819 Keats Otho iii. ii, To thee only I appeal, Not to thy noble son, whose yeasting youth Will clear itself, and crystal turn again. 1880 Blackmore Mary Anerley I. ix. 113 (Like dough before the fire) every well belaboured [bed] tick was left to yeast itself awhile. 1891 C. Dawson Avonmore ii. 35 Racing seas, with their yeasting waves. 1902 Brit. Med. Jrnl. 14 June 1463 The presence of purin bodies in beers is probably due to the yeasting and processes of manufacture. 1921 A. Huxley Crome Yellow ix. 88 It must inevitably take a long time for Armageddon to ripen, to yeast itself up. |
▪ III. yeast obs. form of
east.