a person with h i s nasal passages blocked due t o a head cold t o p s r t i c i p a t e METHODS OF O E T R H I N / N G FLAVOR CONST1TUENTS l N NEAT

Transcription

1 203. METHODS OF O E T R H I N / N G FLAVOR CONST1TUENTS l N NEAT There are maw papers i n the s c i e n t i f i c literature dealing with tenderness, some vith juiciness, but only a f e w with flavour and aroma. This paper is a review of research methods which have been used i n the work on flavour and aroma. Most of the recent work has been done with poultry meat. Nothing has been found, however, that would indicate that the principles established in flavour work with poultry meat would not apply t o t h e socalled "red meats". Some of the research methods which have been developed may be useful i n devising a quantitative method f o r flavour evaluation. These methods would certainly be of value as a basis for further work on the identificatian of flavour constituents. Preliminary Observations Salomon (1943) observed that raw meat did not have meat flavour but t h a t t h e flavour was present after t h e meat was cooked. Crocker (1948) reported some work which Indicated t h a t meat flavour was developed i n the muscle fibres during cooking. Beef, pork, lamb and chicken were used in t h e experiments and it was stated that results were similar for a l l of the e a t s. The flavour of raw, fresh, lean meat was described as "bloodlike". The juice was extracted f r a n the lean neat by pounding, squeezing i n a hydraulic press and leaching i n water. The juice was found t o b v e t h e "blooduse" flavour and the r a w fibre p r a c t i c a l l y no flavour. Boiling the juice did not produce t h e meat flavour. Boiling t h e separated f i b r e, however, did produce t h e typical meat flavour. When the cooked f i b r e was chewed while the nose was open, the meat flavour was experienced. The flavour was not experienced, however, if t h e nose was closed during chewing. This would indicate t h a t t h e constituents of meat flavour were v o l a t i l e umler these conditions. Meat flavour seems t o be detected as an d o u r or aroma by the olfactory center a t the top of t h e nosea The taste buds i n the mouth probably do not make a major contribution t o the experience of meat flavour. It is a wellknown fact t h a t it i s useless for a person with h i s nasal passages blocked due t o a head cold t o p s r t i c i p a t e on a taste panel. It was found by Crocker that beef flavour could be steam d i s t i l l e d. The ph of the d i s t i l l a t e was 9.3 canpared t o 5.9 for raw beef. It was also reported t h a t fat, bone and bone Paarrow did not contribute t o meat flavour, but t h e methods used t o demonstrate t h i s finding were not presented. T h i s

2 204. observation has been supported by work with chicken reported by Pippen e t al. (1954) who found that bones and skin did not contribute much t o chicken flavour. A number of very interesting methods were used by Bouthilet (1949, 1950, 1951a, 1951b) i n a s e r i e s of experiments on t h e development, extraction, concentration and fractionation of t h e flavour constituents of chicken meat. Development of Flavour Ground chicken was cooked i n water a t various temperature and time combinations t o determine the optimum conditions f o r preparing a broth. It was found that temperatures over loooc. produced a burnt odour. The best broth was produced by gentle simmering of chicken i n water, equal parts by weight, f o r 24 hours at temperatures just below 100 C. Complete development and extraction of flavour from t h e muscle fibre was obtained in 48 hours. from Broth Extraction of Flavour Three methods were used f o r exbracting flavour constituents from chicken broth. I n one method, the broth, including the muscle fibre, was dialyzed against cold distilled water by mems of a cellophane membrane. The flavour was found i n the dialyzate. I n another method, a flash s t i l l o r steam stripper was used t o remove t h e flavour constituents f romthe broth. It was found necessary t o first remove the fat from t h e broth by permitting it t o starid u n t i l the fat s o l i d i f i e d and then f i l t e r i n g through glass wool. It was also necessary t o keep t h e solutions hot during processing t o prevent t h e accumulation of g e l a t i n on the apparatus. The t h i r d method used f o r extraction was R low pressure steam d i s t i l l a t i o n procedure. It was necessary t o keep steam pressures below 5 pounds t o prevent t h e formation of a burnt odour. Concentration of Flavour Two methods were used f o r concentrating the flavour constituents. I n one method, nuollte A3 and C3 ion exchange columns were used t o separate t h e flavour c o n s t i t w n t s frcan t h e water dialyzate obtained from chicken broth. The fhvour xas absorbed i n t o t h e anion coiwan from which it was eluted with scdiwn hydroxide. The flavour constituents were then further purified by steam d i s t i l l a t i o n of t h e eluate. It was necessaqj t o neutralize the eluate i n order t o d i s t i l l the flavour from it. Difficulty was experienced i n condensing the vapour due t o acidic components carried over with it. I n t h e other method, a s t i l l with a reflux fractionating head and a 10plate, Bruun type, bubblecap column was used t o concentrate the flavour constituents contained i n t h e distillates frcm t h e flash s t i l l and low pressure steam s t i l l. The d i s t i l l a t i o n was carried out a t atmospheric pressure and a temperature of about 100 C. Each run through the fractionating s t i l l

3 205. was reported t o increase the concentration 10 tims. A flavour concentrate 10,000 times as strong as t h e original broth was prepared by t h i s method. This concentrate was very unstable unless refrigerated a t the temperature of dry ice. An i n t e r e s t i n g technique ms used by Bouthilet t o estimate the concentration of flavour i n the flavour extracts. A series of dilutions i n multiples of t e n was prepared by mixing one m i l l i l i t r e of flavour concent r a t e with 9 miuilitres of water, then i n t u r n mixing one m i l l i l i t r e of t h e first 1:lO d i l u t i o n with 9 millilitres o f water, and so on f o r succeeding dilutions. The d i f f e r e n t concentrations were tasted t o determine the greatest d i l u t i o n at which the flavour could be detected. Further refinements of t h e d i l u t i o n r a t i o s were then made t o estimate the flavour threshold more accurately. A basal medium was added t o the samples t o be compared with the o r i g i n a l broth, i n order t o simulate t h e properties of broth, other than flavour. Fractionation of Flavour Three methods were used t o separate the flavour constituents i n t o fractions. I n one method, two runs through the f r a c t i o n a l s t i l l described above were made t o produce a 100fold concentration. It was observed that the first 20 per cent of the distillate possessed the true chicken flavour and the remainder had e "meaty"flavour, indicating that there were two separate flavour constituents e The flavour concentrate from the second run through t h e fractiona t i n g s t i l l was treated with mercuric sulfate and the p r e c i p i t a t e was removed by f i l t r a t i o n. The filtrate ms again run through the fractionating column. The concentrate obtained was found t o have a "fattyacidlike" odour, indicating the presence of a t h i r d flavour constituent. In another method the flash s t i l l referred t o previously was used under conditions of high vacuum. The d i s t i l l a t e from low pressure steam extraction of chicken broth was acidified and distilled over a t high temperature i n t o a series of three t r a p s cooled i n t u r n by i c e and salt, dry i c e and acetone, and l i q u i d nitrogen. Two flavour constituents were separated by t h i s method. The dry i c e t r a p contained material with a fattyacidlike odour and the l i q u i d nitrogen t r a p contained a yellow, o i l y material w i t h a chicken odour. The t h i r d method f o r fractionation of flavour constitutents consisted of a solvent extraction procedure. The d i s t i l l a t e from low pressure steam extraction of chicken broth was acidified and again distilled. The acidic distillate was extracted with isopentane i n a liquidliquid ext r a c t o r f o r 10 hours. Absolute alcohol was added to the solvent extract and the isopentane removed by evaporation. The alcohol solution was filtered and stored a t 2OOC. A whtte fattyacidlike material s e t t l e d out of solution and was removed by f i l t r a t i o n. A yellow o i l y material l e f t i n solution had a chicken odour. The water solution l e f t af'ter t h e isopentane extraction a l s o had. the chicken odour.

4 206. Conclusion The pyrogenic flavour development which occurs a t t h e surface of meat q o s e d t o high temperature was not studied i n the work reviewed. Chicken flavour was separated i n t o three constituents, a meaty flavoured portion, a characteristic chicken flavoured portion and a fattyacid flavoured portion. It would be interesting; t o learn if t h e flavours of beef, pork and lemb are cormposed of similar constitutents. On t h e basis of the research methods presented, it m y be suggested t h a t meat flavour i s best developed by cooking at temperatures slightly below 100 Cb The flavour constituents may be extracted by dialysis or steam d i s t i l l a t i o n. They m y be concentreted by ion exchange or fract i o n a l d i s t i l l a t i o n. The flavour constituents may be separated by fract i o n a l d i s t i l l a t i o n, high vacuum steam d i s t i l l a t i o n and solvent extraction. It WBS not possible t o include in t h i s review t h e many analyses which were made i n attempts t o identify the flavour constituents or the many speculations about known campounds which may be related t o t h e flavour constituents Bi b l i o g r a m 1. Bouthilet, R A note on the nature of chicken flavour. b o d Tech* 3 U S (1949) 2. Bouthilet, R. J Chicken flavour: separation ad concentration of i t s v o l a t i l e components from broth. Food Res. &Ej 322 (1950). 3. Bouthilet, R. J (a) Chicken flavour: the fractionation of the v o l a t i l e constituents. Food Res (1951) Bouthilet, R. J (b) Chicken flavour: the source of the meat flavour component. Food Res (1951). Crocker, E. C Flavour of meat. Food Res (1948). 6. Pippen, E. L., A. A. Campbell and I. V. S t r e e t e r Flavour studies. Origin of chicken flavourt J. Agr. & Food Chem (1954) 7. Salonon, M The meat flavour. Food I4inufacturing 9 1 (1943)

5 207 MR. AU": Thank YOU, Bob. Dr. Vernon Juhnson will lead the discussion on t h i s paper. MR. JOHNSON: You have heard the thorough discussion on the methods of detertnining flavor constituents of meat. Do you have any questions t h a t you would l i k e t o d i r e c t t o Bob o r anyone e l s e? I t h i n k you did a good job, Bob. MR. AUNAN: I think before we go any further we w i l l ask Bratzler i f we can have a break. Is it all right with you, W e m i g h t be imposing on the l i n e of thought that has been stirred up here by the last couple of papers. Gmn? MR. WANDFE4SIWK: Why don't we have Qmm s summary and then t h e break? MR. AU": A l l right, Lyman, i f you w i l l take over and give t h e summary discussion at t h i s tine, please. MR. BRp3cZLER: The question has been raised a s t o whether or not we w i l l take the break during the summary. It i s perfectly all right, gentlemen. It seems presumptuous f o r me t o summarize after the various papers have been discussed. I ant not as young as some of t h e young ones. I used t o think I was, but a6 the years go by we gradually begin t o feel a l i t t l e older. I have just a few points that I t h i n k m i g h t summarize the excellent presentations of t h e Research hkthods Committee. I think my biggest impression from l i s t e n i n g t h i s afternoon i s the l i t t l e progress we are making and have mile and the need f o r continued e f f o r t along the l i n e s of research methods. F i r s t of a l l t h i s morning on the estimation of body composition I t h i n k we c m compliment t h e gentlemen who have done t h e work, whether i n t h i s group or i n other groups. They have used quite a b i t of imaginat i o n and ingenuity in their various approaches. I heard some comment that it does not work, but I think we should not be deterred by observations of that kind. One t h i n g I was impressed by and I have always been and have tried t o maintain i s cooperation with research personnel i n other departments. In meats we think along one l i n e and we too often overlook a l o t of information that our cohorts or our cooperators are interested in, p a r t i c u l a r l y in t h i s hormone work, flavor work, etc. I am sure we could get considerable help by having more active cooperation. On methods of measuring color I have only one note here. This, of course, is on the carbon monoxide treatment. The first letter we got back was more or less a brushoff saying that it had been reviewed, etc., and t h a t there was no use of going any f'urther but I could

6 208. not be quieted quite t h a t easily, and the second l e t t e r l e f t the door open as t o whether or not the method w i l l be approved. I n other words, anything that we suggest t h a t w i l l tend t o increase the chore of inspection I think w i l l not necessarily be frowned on w e l l, you know, Just like when you and I axe going along and somebody suggests a new method that may involve a l i t t l e additional work or thinking we w i l l say "no," but i f t h e nuan i s p e r s i s t e n t we will change our minds. 0 I t h i n k B i l l Sulzbacher h i t upon one thing. I am rather intrigued with the idea of harnessing these bacteria t o help us, not thinking of them only from a negative standpoint but as also having a positive angle Also t h e matter of plant sanitation. Alwaps the shoe f i t s a l i t t l e and I know that Butler w i l l think t h a t surely it should fit on t h i s matter of plant sanitation. One thing we did learn fram 0, D. We at least learned how much detergent t o use and how often. Another thing that B i l l t o l d us t h a t is very helpful t o those of us who are interested is where t o go f o r information. Elone of us i s capable of remembering everything and if we know bhere t o go f o r information that i s very helpful. The matter of assaying drws and hormones brings up a point that I have been concerned with. The Pure Food and Drug and also I suppose the Meat Inspection Branch who are not too familiar with that rely considerably on the results t h a t come from our experiment stations. I don't t h i n k we should think of ourselves as one experiment s t a t i o n i n trying t o promote something in a hurry t o be first, whether or not it is r i g h t, because t h e reputations of all t h e experiment s t a t i o n s are a t stake, I think, i n stme of these problems, p r titularly vhen it comes t o t h e residual e f f e c t s of sone of these drugs, feed additives, iqplantations, e t c. If you will look back through last year's p r o c e e d i q s you w i l l find that Mr. Herring gave a p r e t t y good explanation of how t h e Pure Food and Drug Administration w i l l react t o any application. On meat conposition I am a a d t o hear that we have no measurement of tenderness t h a t is accurate. I f'ully agree with t h a t. f understand t h a t one has been patented by Paul Gazer down at Swifts and I am sure t h a t there i s considerable room f o r bpovement on t h i s subject. As t o flavor it goes without saying that each of us have our own appreciation and flavor desires, and I think along t h i s l i n e t h a t we should as meats men pay more a t t e n t i o n t o w h a t flavor the consumer would like and looks f o r. why develop a type of hog o r a kind of meat without consulting t h e consumer? Why t r y t o s e l l something t h a t needs s e l l i n g mainly because we t h i n k it is right? The same thing i s t r u e of flavor MR. AU": Thank you, Qman, f o r t h a t f i n e review, A t t h i s time I should l i k e t o thank the members of the com nittee who were so gracious as t o present ideas f o r papers and also t h e

7 209 e participants f o r t h e f i n e manner in which they gave t h e i r papers. I think they deserve a big hand, and I certainly do thank them from the bottom of ~qyheart. CHAIRMAN j u s t 8 minute. W e introductions. W e time. D r. Schulz, I s right behind me KLINE: Just two announcements before we break f o r have a few newcamers i n our m i d s t since our last have heard from one of these gentlemen from time t o from the Food Technology Department a t Oregon, who here. We have a gentlemsn over there by M&rshauHeck, frm the Farm Bureau i n Arkansas. plr. Hardin Then a gentleman right over there next t o Phil Anderson, who i s rather familiar t o t h i s group, Professor Loeffel from Nebraska. Aad over by Larry Kunkle is Dean Weber from Kansae State. Is there anybody whom I have overlooked? Dr. Kraybill was here. I guess he has stepped out. Kraybill is from t h e American Meat Institute Foundation. Now ve a r e going t o rece88 f o r f i v e minutes. t h e l i t t l e box, Dr, Don't forget (Recess. ) C H A I I l ~KLINE: ~ I think t h a t a t t h i s time according t o the program we should c a l l on George Wellington, Chairman of t h e Teaching Committee, t o make 80me announcement8 w i t h regard t o the next two days. George,