AROMA OF BUTTER.

Otago Witness, Issue 2509, 16 April 1902, Page 6

AROMA OF BUTTER.

Mr 15. Gib&on, to vlio.se judging of butter at the shcv of fat cattle, gram, and dairy produce held in Dublin in Decmber last reference i& made in last week's Notes on Rural Topics, is the Limerick merchant ■\\ ho recently, in reply to iome disparaging remarks, of Mr Faber. the Danish Commissioner in England, regarding Iri^k butter, challenged him to a test for quality of an exhibit of 20 tons or over of the article as exported from Limerick against a like quantity of the Danish exports. With a full knowledge of the questions at lstue — uot merely fiom the theoretic and scientific point of view, but also from practical and commercial obseivation, Mr Gibson wrote : "The Danes adopted pasteurisation becuu*- ■ of the silly law preventing the use of pcilectly v h'>le->orne preservative^ in tlieii country. They thought this method v. ould make their butter keep. What is the re-uli ? Simply an all lound low ei ing of the quality of Danish butter, making the butter of dairies that before were regular and reliable more often than not nasty, oil-flavoured B>tuff. and even at be»t absolutely devoid of the great essential of good butter — viz., good aroma. People may tell me lam mad about 'aioma,' but if I am there is method in my madne'-s. I see that any butter po^se^sing a good aroma sells at once at a high pi ice. while butter without r.ifiina is ta.-ttd and thought over and hesitated üb'jiit, perhaps p.i.ssed by. and only bought v. hen >dl that ha« good inoniit has l)em taken, and uheu it is • Hobson's choice • that oi none Since this »-terihsit.on process was adopted in Denmark. Danish butter has no good aroma, but very often quite as bad an odour as the worst Irish. At best it «3 flavourless, lardy .stuff ; at worst it is more oily than the worst maigaune." It is particularly nolewoithy that the Danish Commissioner did not accept Mr Gibson's challenge to tesL the quulitie- of Irish and Danish butter in con&'dirable quantity. At id Flavour, Aroma. — It has been found that tipening ib practically alwajs accompanied by a souring of the cream, so much so that in most parts of the world it is c.i lied '"cieam souring. ' It has been found that good flavours' aiu especially developed by the ac.d-forming «->ieeits of bacteria. It lia^ been assumed, thci.foie. that the development of flavour and the development of acd aie essentially identical, or at leafct neces > ».iiilv awiciatid. Some- practical as well as v.-iei.lific butlermakeis are teaching th t one essential point to be aimed at in the cieam liptning is to cause the acid pioduung oiganisms to giow rapidly in older to develop an acid and flavour before the other organisms have a chance to increase The fact that the extent of the iipcnin^ is determined by the amount of «w irlny tonvevs the impression that the upiuing and soiuing arc identical. Theidea wa\ however, advanced by Professor Conn some yiars ago that flavour production in nidi jx'iiduil of and pTuduction, and uhi'e lni'iy of tin acid-])i odm-ing specief, a!«o produce < h m_;c>- in the lumih w Inch give list- to a good (l.ivnui. equaMv good flavours niav be obtairud by i --pi j < ics of bacteria that prod u< i 1 ii" <vi.l The lelation of iipeinng to the aroma of but tor l^ also an uirfrtain one. According to Professor Cuiir. — who^e expuimeiiN to deteimine the "influence" of bacteiia in the daily are now famed — theie are sev.ial pure cuHuies u-c-d in different daubing countries for artificially ripening cieam, ino-t of which pioduce favourable results "-o fir as concerns acids and flavours, but none of which appear to giv.' a sati^factoiv ainm;>. Aiorna Independent of Flavnin and Acid -Pci Imp- file mo~l initiestm^ re&ult of Professor Conn's investigation has to do with the production of the buttei* aruma — th' character!* ti< that .iff<<ts \]\e nose rather than the pnl' le. '!'!• p\pr urncM Iha\e r-hov.n thft the pioflm.tn«.. of <i<miahla aroma i-> en'jjreix ir.iJ.&o&)jLeiil oi iW

your and acid. Moreover, it appears to be . a moie unusual thing for bacteria to produce a desirable aroma than a desirable flavour. The great majority of the species tested gave rise to practically none, or ab least to an extremely slight aroma. Of 65 species who^c possible effects on ?iom,i were observed. 39 produced no aroma at all. Seven of those producing no aroma are among those that produce lactic acid. Among tLe 65 species studied, only tight were found to produce an aroma described' in the laboratory notes as '"good'" ; and in only three has the aroma been that which 1 is looked for in first-class butter. In two or time cases the aroma produced was of an extremely fine character. It was interesting to find that of the eight species which produced the aroma that has been described as good, none have been found among the acid-producing organisms. The eight either develop an alkaline reaction or Lave no special effect upon the reaction of milk. There were three which developed the mo-t typical aroma of all the species studied (No- 66, 69, and 104). Two of these curdled milk by producing a rennet, both liquefying gelctine. The third did not curdle the milk. "This result," Professor Conn wiites, "has been a surprise to me, inasmuch as I had supposed before the experiments began that tRe aroma was a. matter very closely associated with the development of lactic acid. These experiments ore not sufficient to settle this question, especially since efgh't species only have be?n found to pioduce a decided aroma. It may be that in further experi- * ments now going on lactic acid species also will be found associated with the development of aroma. It is. however, interesting to note that in the hands of European bacteriologists, so far as their experiments have gone, somewhat similar restilts have been obtained. Tliere are upon the European markets several different kinds of pure cultures of bacteria used by creameries for ripening their cream. All of them are of the lactic acid type, and none of them :.re capable of developing aroma to any considerable extent. Recent work of Weigmann further confirms this result. While he is inclined to think that aroma, may be produced by lactic organisms, ha regards the aroma as distinct from the acid quality, and the species of bacterium he experimented upon as producing the bes(, aroma was not of the acid-forming class." It is further stated in Professor Conn's report that beyond question the aroma is due to volatile products, and these would most naturally be expected as resulting from albuminous decomposition. Lactic acid itself as is well known, has no odour at all. and while sour milk has a peculiar odour, this odour, as was pointed out by* Lister long ago, must be due to other products beside'- tactic acid. The butter aroma, however, is not the odour of sour milk, but i« one distinctly different. It is, consequently, an interesting and important jmint if we find that this butter- aroma is associated with a different class of or--ganisms from those which produce lactic acid. Herein may probably be found aj partial explanation of the reason that the aroma of butter developed during the first three months of summer is of a higher character than that produced during other months of the year, since, as already noticed, at this season the cream is provided! with a larger variety of bacteria, and. therefore, among them there is a greater chance of finding not only those producing acid, but also some which give rise to an aroma. It has been found in these experiments that, none of the species tested combine all of the three characters — the power of producing flavour, acid, and aroma. Some develop flavour with the acid, others develop aroma with flavour, and others develop aroma without any special flavour. As vet no single species has been discoveied that produce*- all simulhineouslv. This result is not, of roui'-e. sm prising, for, recognising that the lipcmng of cream must be an extrem-jly complicated process, and produced by a large number of species of bacteria working together, it is a natural inference that tbe different qualities in the butter may be caused by different species of bacteria. It is by no means to be implied, however, that the three properties may not be combined in any one species of bacteria. Professor Conn's experiments, in continuation for over two years, established the fact that no known culture of bacteria will impart to pasteurised milk the desired flavour and aroma necessary to the production of a fir-t-cla>ss and keeping butter. Weigmann. whose "cultures' have been on the market and in request for some timt. sought to isolate those bacteria essential to the best ripening- of cream from those that are useless, and inferior, and thus prepare a pure culture which, added to the sterilised cream, would give butter of the. purest quality and the finest flavour He obtained a pure culture of the acid-pro-ducing bac-Lria and added it tr> pasteurised cream, and churned the cream into butter. "The butter was of absolute purity. and kept well for a length of time, but failed in w most important particular — it had no nrema, no flavour, it was faultlessly faultless, splendidly null." The ouestion forcibly presents itself, Where did bac-terlolo-eW'* seek for bacteria likely to be productive of flavour and aroma in milk products? The answer is, In dairies celebrated for tlr fine nualitv of their butter. Practical ly, the Trouble is tli.it 99 per cent, of the rn-ivni--r« f.f l.uttc h <v- no .j.pi<--ciatifiu or knowledge oi* flavoui and aromn.