Some effects of refrigeration on sulphured and unsulphured hops

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Title:
Some effects of refrigeration on sulphured and unsulphured hops
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Book
Creator:
Stockberger, W. W ( Warner Webster )
Rabak, Frank
United States -- Bureau of Plant Industry
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G.P.O. ( Washington )
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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
        Front Cover 3
        Front Cover 4
    Title Page
        Page 1
        Page 2
    Letter of transmittal
        Page 3
        Page 4
    Table of Contents
        Page 5
        Page 6
    Introduction
        Page 7
    Preparation of the hops studied, and physical changes in the hops in cold and in ordinary storage
        Page 8
        Page 9
        Page 10
    Changes in the volatile constituents of hops in cold and in ordinary storage
        Page 11
        Page 12
        Page 13
        Page 14
    Changes in the hop resins
        Page 15
    Physical and chemical valuation compared
        Page 16
        Page 17
        Page 18
    General significance of the results
        Page 19
    Summary
        Page 20
        Page 21
        Page 22
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text



D E
UNIV y
BRARY




U.S.EPATMENT OF AGRICULTURE
BUREAU OF PLANT INDUSTRY---BULLETIN NO. L
B.T UALLUWAY, irlR ft.
ME EFFECTS OF REFI'llGER 'I
N SULPHURED AND UiNSUL-
PHURED HOPS.
BY
W. W. STOCIKBEERE. PhyjdoTogist,
AND
FRANK RABAK, Ohemical Biologist,
rPlant, Poisonous-Plant, Physlilogical, and Fermentation Investiga4ns.
WASHINTON:
OVERNMENT PRINTING OFFICE.
192




. . . .. ........




U. S. 1)IEPART'II.'T ()F M(;RI( 'IITi RE.
BUREAU OF PLANT INDUSTRY BULLETIN NO. 27L
U. T. 0.1.t h 11 < e a o
SOM E EFFECTS I ) ItE'lA T ION
ON SULPl lUl RE) A NI) UNSUL-
PH UR lI) 11MPS.
BY
W. W. ST(,'Ii H iA ER. Ph lvioloit,
AND
FRANK RABAK, Chemical Hiologist,
Drug-Plant, Poisonous-Plant, Physt~iohicl, and Fermcntation Investigatiovs
WAHTNGTON
GOVERNMENT PRINTING OFFTCE.
1912.




BUREAU OF PLANT INDUSTRY.
Chief of Bureau, BEVERLY T. GALLOWAY.
Assistant Chief of Bureau, WILLIAM A. TAYLOR.
Editor, J. E. ROCKWELL.
Chief Clerk, JAMES E. JONES.
DRUG-PLANT, POISONOUS-PLANT, PHYSIOLOGICAL, AND FERMENTATION INVESTIGATIONS.
SCIENTIFIC STAFF.
Rodney H1. True. Physiologist in Charge.
A. B. Clawson, Heinrich Hasselbring. C. Dwight Marsh, W. W. Stockberger, and Walter
Van Fleet, Physiologists.
Carl L. Alsberg, H. H. Bartlett, Otis F. Black, H. H.. Bunzel, Frank Rabak, and A. F.
Sievers, Chemical Biologists.
W. W. Eggleston, Assistant Botanist.
S. C. Hood, G. F. Mitchell, James Thompson, and T. B. Young, Scientific Assistants.
Hadleigh Marsh, Assistart.
G. A. Russell, special Agent.
271
2
ADDITIONAL COPIES of this publication
may be procured from the SUPERINTEND-
ENT OF DOCuMENTS, Government Printing
Office, Washington, D. C., at .> cents per copy




I.E'ER )1 TR.\ NS \ ITTAL.
U. S. IV tilT E lN Ir I If i RTP,
t I I I4 Iw o k IiI (- IIII F,
()OFIE oF iTMl (111Ev,
iW / hirt-uon, (C., ,' p/, /,,I IS, 1912.
S : I have the holior to tran nmit hlwile itli nalnd to rconiiniend
for piublieation tas Iullhtin No. 271 of ,the eirie-; of this inrean ra:
imanueriIt by 1)r. WV. W. Stockberger. Paiii )logit. aid Mr. Frank
Rabak, (heniical Biologist. entitled Sniie Eofec'ts of liefrigeration
on Sull)hlured and I usulphured hopl>, uhilitl I )r. 11. True.
Physiologist in ('harge of t lie ()tlice of D)rug-Plant, Poisoillus-Plant.
Phyllsiologicll. ind Feiiil't atio n llt -v Irat illli.
In 1iis pap er i Iim.i mn1e of the atillig, WI 1ich ocur in ill-
portant eotit Uentsl of liol ii lnder 1i rf'eii n Vt lit imneM of SNoIrage ntI
a colnla1rison is nade of the relative e10chitl :tc of erta1i 1iiethot l for
preventing untle~irablhe chaties in 0hop in-t ient.
This bulletin hiows that bothi refrigeration and i lllphuiring retard
c2h18n1c in the vohtiihe t'o ilillenit of lo, and lU that thie deter1nina-
lion of the value of hops front thle arolla ra ins icordilig to indi-
vidual preference for or sl ike of one or the other of the aromalitic
COnlistittuentis. Tile ('oincluismnll drawn fIrnii .i t'Oiil)si ion of valia-
tions made fromi both phyVi'al anid A'linidi sIitano liits will be of
practical iinportance to all interested in the iiop itoliiustry.
Retpet fully,
J. T. ( G.1A.IWAVY,
Ilon. .AMY Is VUSN
N 'creta;77 of A y i u/ture.
271




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CONT E NTS.
Pagfe.
Int oduction .................... .........................................7
Preparation i thle hops studied ........................ ......
Physical changes in the lop- in c-d and in ordinary st8rge ..............
Changes in the volatile onloituenll of hops in cold and inll ordinary stora .... 1
Changes in the hop rsins ............ ................. ........ 15
Physical and chemical valuation compared .......... .. ........ 16
(General significance of the results ... ......... .. ........ 1
Su mary ....... ........................................ ........ 20
271
5







141' 7S
SOME EFFECTS OF REFRI(GERATI(O)N ON
SULPHURED ANI) UNSULI'II REI) H10P'S.
INTRODUCTION.
Opinions are greatly divided as to the desirnhilitv or general ex-
pediency of tile practice of treating hop" with t hle fume. of burning
sulphur during the press of drying. This Pirocess, which in the
United States is termed "'sulphuring," has been long in vogue and
has come to be regarded as an essential part of thei method of prepar-
ing hops for market. The IlIe of s1ipI imr a. an mdjunct to hop
drying apparently originated in EI-nglaind aril from the firt was
regarded a a ilore or less effective lleall of checkiig the tenlency
of newly packed hops to heat and spoill in thi baIe. Later. other
virtuell- were clainiel for ull)huringll adt litiou to that of pre-
rvatille action, and those who aldvtctte the u11e ,if sulphur now
believe that it favorable aifect thle hops by changing and imiprov-
ing the color, by hastening the drying tl'hrouglh cauitlg the rapid
death of the (ells. and by preventingg ft'rlint atition, thereby il)prov-
ing the keeping qua alities.
Aside from sulphuiring a Miimer of o other e\pedient' have beenl
Iresorted to fori tile lirpo of delayii g or et ar t llg the changes
which normaTlly occur il the chen ical t c(stit uents of hop after
they have been dried and Ibaled. Of the-e expedients refrigeration
is the imost widl uied ald from Imanlly consider at ions it i perhaps
tie mt elic(ien amid enerall at isfat'tm rv I1t thod of p)reerv atioll
that ha a > et bee l eiphed.
The sulphuriflg of hqs i- s11h a cilion practice in the Illnited
States that l)practi ialiv al1 hops placedI i col, I to re ma be re-
garded ts hav ing aI sorbedf a var'ing (11111nt1ity tOf suilllrouls acitd.,
depending to a certl Tin extenl t upo n tho i In l itty of siill phi r u11ed
at th e tilme of tylving. Since both siIulpIiirin, .n11d cold tora(g' ar
hel to be ef'iieitt a iltlt 11 ta t I img chi: 1 e- i n tli ient ia I on-
stituents of hops. the diminihed rate of deterioration of sulphured
hops in cold storage mut I)e due to thle combhinad action of these
two processes. Ilomever, thet relative ellicacy of these- two presses,
271
3ClI '5




8 SOME EFFECTS OF REFRIGERATION ON HOPS.
or the extent to which the one or the other alone would accomplish
the desired result, is usually a siibject of approximate estimation
only.
For the purpose of obtaining some experimental data upon the pre-
servative action on hops of sulphuring and cold storage, singly
and in combination, suitable material was prepared and held under
observation for several years. The results of this study, which are
given in some detail in this bulletin, indicate that both cold storage
and stilphuring tend to delay certain undesirable chemical *changes
and that the usual trade judgment can not always be relied upon to
give an accurate measure of the extent to which these changes have
occurred. However, it is fully realized by the writers that further
experimentation is necessary before the conclusions drawn from this
work can be considered to have a general application.
PREPARATION OF THE HOPS STUDIED.
The hops which furnished the materials for the observations here
recorded were all picked from the same part of a field on a hop ranch
in the Sacramento Valley on August 30, 1907, and were dried on the
same day under the senior writer's supervision. As the hops were re-
ceived from the field they were equally distributed to two duplicate
stove kilns until each had received a load of about' 4,500 pounds, green
weight. The fires were lighted and the temperature of each kiln
was gradually raised to a point between 130' and 140' F., between
which limits it was maintained iintil the drying was completed. On
one of these kilns 110 pounds of sulphur was burned under the hops
during the drying, which required 13 hours; on the other kiln no
sulphur was used and the time required for drying was 18 hours.
The dry hops from each of these two kilns were separately deposited
in the cooling room and on September 2 two bales of the usual com-
mercial type were prepared from the unsulplitired hops and two from
those which had been heavily sulphured. These four bales were con-
veyed to Sacramento, where two bales, one of sulphured and one of
unsulphured hops, were placed in cold storage at 36' F. in the hop
storeroom of the Buffalo Brewing Co., and the two remaining bales,
one of which was sulphured and one unsulphured, were placed in
ordinary storage in the Clunie warehouse,
PHYSICAL CHANGES IN THE HOPS IN COLD AND IN ORDINARY
STORAGE,
As a rule, it is difficult to correlate the valuation of hops as de-
termined from their physical characters with the indications of their
value derived from chemical analysis. In the present case, however,
271




Il1v1win hmill \a H f dAtil frtti ime1 t ile f Wtil, an 1it* (ldr1 Y
titr it1 i 111 A o lit i r til aie .. t\er l- fil :4 sti n l f *I
1111tile 1 .) 111\( ithei I t tl e. t i tl i, :i ll t :Hil it t
E ri 1 Vinll .:1 rln It %"I it (I I it,' f lops l thia 1 '- it iII -l im fot r let.l
molth -nhl w ere drawn fr'mi 1t11h of UP tl ib:e- :Ntl it
listed It live \ I:tt e\prtsl all of Istil to ner'li-ml i the i 0 f Ini"
report 111ie by oe of Qtir 1fHllwther:
WVte hat vf ur tlrn l te .I llipl o sp:. ( I't tr e it ion .tt t 111he 114 '1''ut tIll111
to we it tIere 1,1:t 1 141 dini+titi e bl t it.l l ;il :\t i 4 1144r1 \ :'r1 ho1 k agd 1
to ucp 1lt 11' ' in r Itrd t~t I tr frtkl tIt' 41 gI I4 4I1h fti' -- it
WlI rett Iot Ithw It"IMa l t'inll 1th1 t thtkl is dit fftit' l trt R h I ll tle 1,t tr'lef
fial refi llarIly tored hops.
a t ti I i lI Iec il f) 4 I i 0 t' ( 1 li Ill it l i f.4 t' 14 r
Thec IImh's -weftr not sampled a wwomi tinie mitil tnid-utnim,. :wip,
durin the time which had el ps ine the first tialplint the blols
ill otr ilirv alu t b e t'll tW 1 din- t to te it'.i4 151 a l 1f the h iot ld
(I we W a tler V hT' l 're\a il I, I, F:11 il o *I\lk v. t t 0 I -t:Ill)n
of tile yelr. Natural y. it wa v1 ml'te tlh1t :11 ONi time (ewatin dif-
f fr ilees W lld III, a| a) rt'll iI I l h j 1 r" ,r h mill 'liti ns of
Storage. (11 11y 24. Nvi, 1 drlwr awn a Slhtlitedi to
an expert hop haver wh reported m than+ t follows:
T'nslphund cold-store+d hops,. Fine fresh hop l!tor; goo{d oily\ feeline:
arO in itmlli t ;is good 18 It 1 i lit d sPtlitm tw W0 NideIait ti 1m11110 Ni tllt of
the sllphtlw coh stored hos.
Nlplthu~red tco}ld-store'd in pe. Fie fr 11si hop thellor: ood W oily feelit :: :in.,
aba~u~st iss good aIs nw hol+ .hit m+!er SOInlt !llter thanl the nh of the
unlpltl[hured a/tmlet :+*hol {th'{s+ribed.
'nslplhure+d ordi ryt~ ;ore+d b ,. i~nvor deldelly th, t of old hops as aml-
parel with the *Al-stan t simpleI: feelinI alr\: ltuin not wr. sucks; color
about the sun1lw :I- 1t color" of the unsllllhored soulew .sho
-ulph frd Irdlurl-sl ored h( ps. line fresh Itmor > g l '.\ fee.H[e. :sreIui:2
almlOs ht l n h th enlar sonllt hat li'dter th.ti f ly ].. t+ of
the uslltilur am1l above sl lilbd.
At this time14 it e ii+ e il noheable thatt th, cond stord h 1, h1% Iby f:or
the best fiavor 4 and that the. feelt : si- ;Is oily ;i n w h(p<. while t l nat,
stored hops re bwcolin* poiftorer.
This jtl *.'l i: l \11 :W %\ I : ll \Wilhd l ill I ;ntif ft1i 1 *l tl- *;t 1h d le I n Ntin led
and on1 tominh into the{ l+an~t where{ thet sumlehw h:d 1+ he t p+lcd I thtight th.0t
th ( xI I I I t IrIIn IwIaI dIe iI :In +ewII hop I ,1,+ 1 rea ,lly rpriwd 1 1 t tIh I t r at
difference ill thl amit the ordinary-stored and cold- towel hopS, lt
65123 --12--




10 SOME EFFECTS OF REFRIGERATION ON HOPS.
on (o ipa ring color I ean not notice any serious difference between sulphured
a ind unsulphuretd hojps in either case.
IThese amie salnples were next stibmitted to a second expert, who
minade the following statement:
The difference between t he ordinary-stored and the cold-stored hops is now
very noticeable. The linsulplilred cold-stored sample has a very good flavor and
looks fresh anid bright. The unsulphured ordinary-stored sample has not such
a good lhla-or as the former, is very much drier, and is becoming rapidly aged.
The difference between these two is particularly noticeable in the appearance
of the siies of the samples, the side of the cohl-stored sminple showing up muhb
brighter a nd fresher than that of the other.
The sulphured cold-stored sample has a fine fresh flavor and is a particu-
larly well-kept hop. while tle sulphured ordinary-stored sample has a musty,
old flavor and is rather dried out. The difference between these two samples
is not so nlmuch in the appearance is in the aromna.
On the day following, these samples were sulbmitted to a brew-
master, who delivered the following opinion:
The cold-stored hops have a lighter color as compared with the ordinary-
stored hops, the lulpulin is bright and shiny, the hops have a very oily and
sticky feeling, and the aroma is almost like that of new hops.
The ordinary-stored lmh)ps have a dull, dry color; the Jupulin is not so bright
and appears to be hard and dry, with very little oil as compared with the cold-
stored hops; the flavor is decidedly different and very much like that of old
hops.
The bales were not sampled again until Feb)ruaiy 13. 1909, eighteen
months after they were first placed in storage. The samples drawn
on this date were first submitted to the brewmaster previously men-
tioned, and his judgment as to their relative merit was stated thus:
The sulphured and unsulphured cold-stored samples are respectively superior
in flavor to the corresponding ordinary-stored samples. The sulphured samples
in cold and ordinary storage are for superior both in flavor and color to the
unsulphured samples.
The samples were next submitted to a trade expert, who gave the
following opinion:
There is a very great difference between the cold-stored and ordinary-stored
hops. The cold-stored sa mples are much brighter in appearance, have much
more flavor, contain much nore moisture. nd their lupulin is much brighter
than the ordinary-stored samples. The cold-stored samples would pass for new
hops, while the ordinary-stored samples show their aIe and could not pass for
anything else than ** olds." By new hops I mean the 108S crop.
Of the cold-stored hops the unsulphured sample seems to have a trifle more
flavor than the sulphured one, but the latter has a sweeter flavor, which I
believe would be preferred. The lup)ulin in both these samples is very fresh
and moist, but that in the sulphured sample is a trifle the brighter. The sul-
phured sample, though in appearance fresher than the unsulphured saniple, is
not as moist as the latter.
Of the ordinary-stored hops the unsulphured sample has much more flavor
than the sulphured sample, the latter having very little flavor at all. The
271




oi'li' of liil'i t- i'(t'tll'l l t "+r iip i' titk '- a' a |ll t-\ AP]tI~II, lt~
CHA NSIN THE\ VO ALE CON IIII'ISIT NS OF HOPS" IN COLDw
oif l Vt il tI\l. a le 'ti l t g lltt i l l t .,* I li l fatii.
Ill o t1, 1 :1s 1h .oe H ll h 1" .l 0 1-1 I ,i d l
il t il, hat loft he I d (0 h i nol ttlti Ila r a he ltJ: -il tli-tt1tr
til1 bhi pIoil lto \ lie :1:1 il / t l iia lv I oi'ig ho it 1a
Ot t 1gto wi l th oal r tytC lit' un" irt h 1101 i odI H ti *
in trade jt"hg lelt of spalii ai v hir wll i nth le u raik it
order of mterti :t fixe A l Sr of th ji iagit a 1a:1- A- l +I o
Il ti illpintree'l ,n ts o e o .
Sull iurtl nr11lintry-s l hS 1. 1. 1I.
CHANGES IN THE VOLATILE CONSTITUENTS OF HOPS IN COLD
AND IN ORDINARY STORAGE.
On Septellier 10. IlK, Imirtiill" of tle f01r IhA- ,f h ,T m u1 h
(1o11sideratil 1't HIgt i n ill nfl 11 .1 t l
distilatiov to remoc thc volatile oils, which Owre hn dried an
l rified mill :1100 eXill led to etb Hiint t oir h _*,tr e of a:isltl rtl
ester contelit. The- fittl n s. tog-eth1 0 r w11 t Ic (ot it'P of \ieht
of volatile oil. are given in T lh I.
Iti+I m I. tonspentsonr ef clutil alls fro+e sulpharrel en* +'en, llple+v 4 1 In
tlphtrol- --r-h---t-r-I ... ......
+tlI+htre+ +rli~~rY st+r++l h l++ ... ... ... ... ........ . ++ +
I n l till1httra~l o+r it'sl~ t+r t 1r ho+les . . . . . . . ..++ ,++
AI ill. pectin of tIhis table te al the ItfA minH1 11 1 i l l til fmN "
(1I) The .vichl f oil is twice n- reat it. ti,. tore h l
those ill ordilitnay storage.
(2) The aidity of the oil from the ohl--, l h, i,. far Iles
thal that of the 1Up> in wdmriy:1( stora +g.
(3) The Ai frmi the -Wl lihwNI h,,lq, in Wrinmy > stnv -+a~ hows\ ait
increas,c (if 71.2 per cent in acidity ,,v+r that fr i+ the hps in (W+h
storage, while t, oil l the 1h1ls i 1rdimt l -( 1 -4.
shows an increase of 7:.3 per cent in iaclit, mer that (if the oil from
those in e(,hi storage.
271




12 SOME EFFECTS OF REFRIGERATION ON HOPS.
(4) The oil from the unsulphured cold-stored hops shows an in-
crease of 23.2 per cent in acidity over that from the hops that were
sulphured, while the oil from the unsulphured, ordinary-stored hops
shows an increase of 24.8 per cent in acidity over that from the hops
that were sulphured.
(5) The oil from the unsulphured ordinary-stored hops shows an
increase of 113.6 per cent in acidity over the oil from sulphured cold-
stored hops.
(6) The ester content of the oil from the sulphured hops is much
less than that of the oil from the unsulphured hops.
(7) The oil from the unsulphured ordinary-stored hops shows an
increase of 23 per cent in ester content over that from the hops in cold
storage, while the oil from the unsulphured hops in ordinary storage
shows an increase of 46.6 per cent in ester content over the oil from
those in cold storage.
(8) The oil from the unsulphured cold-stored hops shows an in-
crease of 32 per cent in ester content over the oil from the sulphured
cold-stored hops, while the oil from the unsulphured ordinary-stored
hops shows an increase of 57.2 per cent in ester content over that
from the sulphured hops in ordinary storage.
(9) The oil from the unsulphured ordinary-stored hops shows an
increase of 93.5 per cent in ester content over that of the oil from the
sulphured cold-stored hops.
This analysis gives an index of the relative efficacy of sulphuring
and cold storage in controlling changes in acidity and ester content
of the hop oils during the first two years of storage. The percentages
of increase in acidity as between cold and ordinary storage are
approximately three times the corresponding increase as between the
sulphuring and nonsulphuring. This would apparently indicate
that cold storage is three times as effective as sulphuring in retarding
increase in acidity. W17ith respect to ester content, the increase, as
between the oils from cold and ordinary stored hops, is twice as
great in unsulphured as in sulphured hops; also as between sulphured
and unsulphured hops the increase in the ester content of the oil is
twice as great in ordinary storage as in cold storage. This would
seem to show that cold storage and sulphuring are about equally
effective in retarding the increase in the ester content and that the
two combined exert double the effect of either acting alone.
On December 1. 1910, fifteen months later, a second set of samples
was taken from the four bales in storage and the volatile oils removed
by distillation. The results of the examination of these oils, which
are given in Table IIH, show little harmony with those of the first
analysis.
271




T I I I 4I % f ) I 1dit l J\I I .J C .i.. ind I / N S 1 i
cold 8911.1* arw I ml I0,r 1 hot..
I~~~~ v I-
8 t! r I I 4I 1 l v* o I I| ... 4 I
An inspection of the (aib,. -i4,\ I '4-:,' 1ie fllo ino I4
tons:
(I ) The acitt of th oil from th. .4,h -t, rcn h,,- en-,ter
than tiat of 1le oil from the h1op-l n oir, linary ,an+i.
(2) Thel aci ities of the oils fmI tie l, i n oWlin'ary a.I r;,+& t arc
the sate.
1 lie oiI+ fr lI l) I I 1 I Il l I I .,* t, ,- I1, iu t Lh -t ill
aciditvy.
(4) Thee eter cIItelt Of the (1- from the ,Id- torcd hljops i-
gtreater thai that of It' oils fro thi Ir, liIa11' ,red hopl .
( T) The oils from tilhe sullphon-l n ,in 4,1h -tarre i h:i lhe-t
in ester vitel1t.
(6i) The oils from the unIIlhurcl hop-. ili clil :nd in or,1linaryV
storage, 70.pe ictlely, are hiher in ester content than the oil front
the sulphured hops in ordinary -torage.
It 1is now evident that the apparent effects of s1lJ)h1rin e and cohl
storage as shown by the secoml an::sis are almost the reverse of
those indicated by the first analy-i-. I low thle-e -ee1ing disrepAin-
cies may be harnlonilzed Ian he een f'rom :an in-4pection of Table III.
in which the results of the two an;ilYses- are directly com pi ared.
TABLE III.--'OlC H t0 etro ,f fitl' Gridifyt) (10 f4 r ',,tent f'It th oi1l /rm4 tl-
phiurcd td i 4(tphrt 4 hop4 in ,i/fl *.1 in7 ofdinar y 4 190/ 9] p
Sulphutrol hI,, o <. ITsIniphureal h ,lqu
age. > ret. hert 4*** *it her4
Milde of fy Af ne* :f a o
It 191 0 1914. l 1lO 1910 1 V* PalO ]'I 1'"O 1'o I
Oohl ......... 73 :0 'l 74 12'.5 M.o 0.0 ..1 t I 1 p 1 3 10
Ordinary ..... 12.5 240 J 0 ; 1 1 20.0 :lS 151 l 2. 0 7.7
Reganlrding. first, the acidity. the data in this table show that the
percentage of increase in acidity wa: least in the oils from the hl(ops
which yielded oils that were highest in acidity in 1909 and greatest
271




14 SOME EFFECTS OF REFRIGERATION ON 110PS.
in those lowest in acidity in 1909. Further, all the percentages of
increase in aidit*v in 1910 are invr-ely proportional to the acidities
in 1909. It is evident from the first analysis that the rate of change
in the volatile constituents under consideration was greatest in the
oils from the unsulphored hops in ordinary storage. These changes
would continue until n maxinitn was reached. after which, owing
to the interaction between the oxidation products of the various
Organic( constituIenlts of the hops and to the direct loss through vola-
tilization, a decline in acidity would he the normal result. Assum-
ing that this maxinium was reached between the time of the first
and the second analysis and applying this explanation to the data
on acidity in Table III, the oils from the hops in ordinary storage
may he regarded as having passed the maximum and as being in the
declining phase with respect to acidity. Since the changes in the
uisulphured holps in ordinary storage were not artificially retarded.
the oils from these would naturally be nearer than the others to the
maximuil acidity at the time of the first analysis. and hence the per-
Centa(ge in increase in 1910 would be smallest.
Of tle hops in cold storage, the oils from those that were unsul-
)hured may he regarded as being at or near the maximum of acid-
ity in 1910. thus accounting for the high figure of actual acidity and
for the relatively large percentage of increase in acidity during this
year. On the other hand, the oils from the sulphured cold-stored
hops had apparently not reached the maximum acidity in 1910,
)m in to the slower rate of change in acidity in these oils due to
the combined effect of sulphuring and cold storage. When viewed
from this standpoint, the apparent discrepancy between the two
analyses disappears and the balance of evidence is in favor of the
conclusion (1) that under the four conditions of this experiment
the acidity of the oil of hops increases to a maximum and then de-
(lines; (2) that sulplhuring and cold storage merely retard but do
not inhibit changes in acidity; and (3) that sulplhuring and cold
storage combined are more effective in retarding changes in acidity
than either alone.
With respect to the esters, the data indicate that, in general, the
changes in ester content have been similar to the changes in the
acidity, although complicated by some other factors which make
the relations of these changes to the conditions of storage less clear.
The first analysis shows that the greatest changes in ester content
occurred in the oils from the unsuilphured hops and also that the
oils from the hop in ordinary storage had undergone a greater
change than the corresponding oils from the sulphured and unsul-
phured hops, respectively, in cold storage. It is possible that the
271




CH4N. i-1: IN Vol0A111E ONSI II F N Ii- IF 1101'- IN.1 1i00 .
.midQ II[' I 1hi ll 16 Y v\t qnilt of 0-101 W '\ lt i 'li HI f,
1i1 H t I ii I l (Hio t 111v 1111: i j ill ih I W I' Mt( m 4q I 11 ""p d th w l uiII
si pl00irc.h hopn m i it 1ni oe for t1 lhe i oi l -d 1 i IIiiIpl ir10 Iliop'
I'lt CIta of Tal e I tII 'e A Aii ii- *1- Hillu I sio f I' V I i:hal
the o f i IITIIlI i tilu t ir -alli:t ri eq Iho, to i t i t i tl i t
iua\iiliili of t-I 'ler moldtllei iI "!I" oi. xhI ii tliere fte illc r rei I hl i\ 1 li i l.
Its 'doW i \ li te fi lure rea'li'tad iii 19I).
Ile oil flin ilt'h liiliilnd li'l ohl dt-orel l oi- tw iti1 1 wit lwhnW
tIe piloaile inaxiliniun of e-ter on tent at the time of aliiv i in
19() '~o ill iA lppareint iii'i'e:i of 22.1i per i'lt in l 1910: Iit. -ilin
(the l igi- i ea lc llh in 1910 i- les- luti (lhlie talle niaxininI :1i
indleated VI he e ie oi Oliteit of the oil- fr'Owni lie liol in oi'rdinar\
storage ll 1t)9 it ilil e11 ietil ( : It liv oils in ihe' 1op iIn i !
stOtgPe had ieTahel th e 1iiiliiiiii a111 l elti'teedl upon the ih-lillilig
phin-e Ibefore lie aialywsi in 1910. This view receive ':- firtiiihelr -uil
port from tile fact that the oil fro ni (l iiphired cohl-iil' l ho.p-.. ii
1whih the cheiniial cIiailigeo Wer0 11e t ietatilml. x:i- iilier iln 1 -ter
co nile t in 1910 than lil li e oil fr'ont llo wh Iih we're iun li ih iil.
The oil- of the -ulllhttrel holp iin iii!\ -Ii. t1"ra, apiwari to hia c
pt Ptted theil iiiaxiii1ii of ester tiellntl ailld to he in the eo'li iniig
phase in 1910. while those of the hops that were -pilliurtd and xlich
low Ihe greira t*tI il'mne in ('-tel' c it' llil 19 it :plp to In at
o1 neit, their n -i1i i1. Thie *inilins- i sii- xxh i ar1 he lit ra i
with respect to It e ster c nt, therefoi'e. are tlit *liI iipurinr2 i'V-
itatd the iIlreae in e(ler contenlit ili ilihiliit it Ie tiiil :a c'irtain
illaxiliilln, that cold 11 4 tol, e reta'd l ut Tie fot il it i1 ri';a-e
ill e-t~ei co1lelit. and I l in phi iiilg anl d tlil ol toi'ait c mboliiilledit al''
inore effective in retarding chliaitge in ester ('contelt t hani either alt one.
CHANGES IN THE HOP RESINS.
In fift her pursnnance of the plan of securiing triate opinis-ii with
respect to the changes which had taken place in tie four l hh of
lops lilider di eIreit (olidition of ie:illent, p irtiilln of lie'e I: les
were wtll to ia firlli w hib 1 i ia larg ol stlluiier of h Il with tit re-
iw t that the colteti of ,oft ili a rdmeii li 0 le teiliine- in l t : li.
The tirst anlViW wal mliade h te te iirit of ihii- ifti n in Ja ila nry,
1910. two vear and four month- afler the khl- iaid been Iir-'t placed
in storahg. ()ne veail later ai seioli lot of il1lple- wais sill to ile
same chemist and by hint duly analyzed. The reuiilt, of the-e two
analyses are given in Table IV.
271




16 SOME EFFECTS OF REFRIGERATION ON HOPS.
TABe IV.-Changes in rsin cotient in sulphured and unsulphured hops in
cold and in ordinary storage.
Percentage of resins.
Prvi ,m treatment of the hops analyze. Soft re--ins. Hard resins. Total resins.
1910 1911 1910 1911 1910 1911
Sulphtired, ev hl stored .............................. 10.5 310.3 5.5 5.6 16.0 15.9
Unsiulphlred, cold stor(eld........................... 10.0 8.7 5.3 6.2 15.9 14.9
Stulphtrved, ordinary stored ......................... --) 7.5 5.5 7.5 15.4 15.9
U,isiilphuttred, ordinary stored ....................... 9.9 7.8 7.0 6.4 16.9 14.2
The figures in the foreg(oing table give an index to the changes
which occurred in the resin content of these hops during the third
year of storage. The slightest change in total resins, 0.1 per cent,
took place in the sulphured cold-stored hops, while the greatest
change, 2.7 per cent, is evident in the unsulphured hops in ordinary
'trage. The loss in soft resins was least in the sulphured cold-
4ored hops, 0.2 per cent, and greatest in the sulphured ordinary-
-tored hops, 2.4 per cent. The loss in soft resins of the unsulphured
hops was 1.9 per cent in cold storage and 2.1 per cent in ordinary
,torage. As far as the evidence from these analyses goes, it indi-
tates that sulphuring diminishes the less of total resins, but does
not dutninish the loss of soft resins except when followed by cold
,torage. The greatest loss in soft resins was in the sulphured hops
inl orlinary storage an(, since the soft resins alone are intrinsically
valuable, from this standpoint these hops must be regarded as the
poorest of the lot. With respect to these particular samples, the
1,alance of evidence indicates that there is a distinct advantage in
Loth sulphuring and cold storage. However, the margin of differ-
< rne in the results of the analyses is relatively small, and if the
soft resins were regarded as the only measure of value, the advis-
ability of incurring the expense of long-continued cold storage might
he questioned.
PHYSICAL AND CHEMICAL VALUATION COMPARED.
Great difliculty is experienced not only in harmonizing the results
of the physical and chemical estimations of the value of hops, as
pointed out on a previous page, but also in bringing into accord
the different individual judgments of quality, determined on a
purely physical basis. This point has been discussed at some length
in a previous publication I and will not be dwelt upon here further
I Stockberger, W. W. The Necessity for New Standards of Hop Valuation. Circular
33, Bureau of Plant Industry, U. S. Dept. of Agriculture. 1909.
27I




PI' Sit'AL AND CHEM'ICAl VALUA fION COMNI'AItlI) 17
than to state that it is well nigh impossible I, tilld two pr l- lM w ho
will aNigi tl siae rank ill n alie to sl i nples of ,niifnicvial hI s
Selected at iall ll. 0111 lIight I I thr l)Wt ll il thee 1if t 'entC es iII
ljudgmlent dyit t d of the ilttereti opilltions rvt'llsIld a lo the
relative v ale of the four -otIs of hps, all frt t1 e hOw t soiirfe liit
subject to different conditions of treatment an sltolra. In order
to brin oult ce arly solit' of t O cotllIfats in lic e op lnlll,. a table
W prijilaed ill wh ic thl e pI lysicWill and ch i'winal I alat ions are
comIpared. In this table the relative rank gi en each lo t of hops
by the four expert judges is indicated by thle c rrespolidng iumeral.
The relative rank in acidity of thle oils. which is i ilarly indi-
eted, was determined fron the results of t he first ana vsi, I inee this
analysis was made neareIIA in point o f time tI thI e physical I valuia-
tions. The hops hav ing thle oils lowest in aciditv wre h Ien the
highest rank, those with oils next in acidity ,c4,nd rank. and so on,
this order being determined byl v tIhe fact that t lie hops having oils
lowest in acidity had changed least from th e original voni it iIn at
the time of first storage. The relative rank with respect to eAter
content was determined in the same manner. The relative rank
with respect to resins was determined from the content of s,,ft
resins, as these alone are considered to )e the only resins of s alue in
the utlization of hops. Since k'eping quality, as indicated )by a
slow rate of change in the chemical constituents, is an important
factor of value it was made the bais of relative rank in this case
rather than lthe absolute quantity of -soft resin. This relative keep-
ing quality was determined from the difference in the content of soft
resins, as shown by) the two analyses. A direct conmiparison of all
these relative rankings may be made from Table V.
TABLE V. Comp1rioens? of rankings in rolvI of ,uld furd and unsulph urtId lho#p
in cold florag' and in ordimurry torage.
Rank In value determined as noted.
Fly
Previous treatment of the hopi. fly trade pts. By kei ng
By ester qalt
................... ..acidity. m e t:tof tt
A. B. C. D. tent r ins.
ttlphttred, told stored......... ........ ..... 1 1 1 1 1 1
Unsulphured. cold tored.............---------------- 2 2 3 2 2 3 2
SulphuredN, ordinary stored --------...........-- ... 3 4 2 4 3 2 4
Unsulphured, ordinary stored............... 4 3 4 3 4 4 3
From this table it appears that the rankings as to value are con-
sistent in one case only, that of the sulphured cold-stored hops. IHow-
ever, on taking the judgments of the trade experts singly, that of
expert A will be seen to agree with the rankings determined by
271




18 SOME EFFECTS OF REFRIGERATION ON HIOPS.
acidity, that of expert C with the rankings with respect to ester con-
tent. while the rankings of experts B and D agee with the order
determined by the keeping quality of the soft resins. The reason for
the differences in tihe judgmnents, based largely, if not entirely, upon
the flavor or arotna of the hops, seems to lie, in part at least, in the
difference of degree of sensitiveness of the individual to the several
volatile constituents. which together form the aroma. It is well
known that odors which are agreeable to some persons affect others
unfavorably, and there is every reason to believe that in the present
case the differences in judgment were due to the physiological idiosyn-
crasies of the observers. That this point of view is coming into
wider recognition is shown by the following statement made by
IDr. Albert Fischer:
The determination of aroma is an entirely individual matter, depending upon
the individual taste, the state of health, and the eventual influence of outside
flavors on the person testing.'
However, since the number of individuals who passed judgment
upon the experimental samples was small, the decisions rendered are
not necessarily conclusive and certainly do not prove that the aroma
should not, be used as a factor in the determination of the value of
hops. That the aroma is useful in determining the age and sound-
ness of hops is conceded even by those who hold that it -s not a
proper factor from which to determine intrinsic value. The term
" age may be used to express the time that has elapsed since the
hops were harvested or, in a relative sense, to denote the extent to
which unfavorable changes have occurred in the hops. The hops
under discussion here were of the same actual age, but owing to the
different conditions of treatment they were of different relative ages,
as shown by the different points to which the changes in the chemical
constituents had progressed at the time of analysis. From the several
classification,- shown in Table V it is evident that the relative age
and degree of deterioration as determined from analysis will depend
very largely upon which one of the various constituents is selected
as the basis of comparison. Slinilarly, the estimation of age or dete-
rioration from the impressions produced by the aroma will vary
according to the Individual peculiarities of taste or fancy possessed
by the observer. It is imich to be regretted that there is not R, better
understanding of thie relations between the factors commonly con-
sidered in establishing the relative market value of hops and the
actul vlueof he hps n te pocesses in which they are utilized.
The determination of a definite basis of value from which sound
standards could be derived would have great practical importance,
both for the producers and foi- the consumers of hops.
lFischer, A. Modern methods of hop analysis. Letters on Brewing, vol. 11, 1912,
p. 317.
271




GENERAL. SIGNIFICAN'E OF TIllo II I. 1 I I'. 19
GENERAL SIGNIFICANCE OF THE RESULTS.
Tple matInierial hit f1imih-d tile basis for tli n1, ,Arlatialln dil
ciS4'd in thil- pmlper w a lpea'ifed primarily wilh tle 1 iew to l Air-
inintng llt feaily oflil tialdia ilo iig thle piracli'e of ulllirilig hni.
Some lprr. ion.s PXlwrhrid~s hadu Ohwn I that undher verthini(o~iim
there \wa -mie daltiger of Ios lht'tillinT lg!ihih imfaltilitiutti Hw it
i ttenic dhIriig l 1t cIt of .ll lhiliriIg. to (h11)\ 0at' H i 1 (lit t -
conlitnuance of thp' Iue of siIlit r : a: naturally -ulggi'(tI. It wa
expIected that the unulpihured hlop woul be re'eiedi with l-
favor ly th1 th th l:1 t(i 0 h which haI t wll -I h11hrel. oH' iIg to
tIhe 1ore J)proilat' lf varialtiull in (lie cohr of the forifilr, lit at
the tim the Iahs of hol seltd for ob-,rvation were pInWO, in
'-torage the dit reitc' in gt'lntral wlqlairanlie was COliatratively -ill .
although the ulpliured hlpim'oihl lI r1,adily di-tinguis'el Iby th eir
11Ore IIliform anid solliewhat brighter o hor. A ~t Iilv of thle trade
opilnioni rI'cldrd ol these hio> after they hat l Ieen f somile time
in storage a apparently shows that the h i ffrne int~ l)l:ara 1ce dIe
to sullhurig h)ec(oe- accent alot 1 ItgI ait nd that tle preference
is for the sl)phIire"d hop.
When fr hl cN mvel. the di re ''il in c' Ilor b etween sii llhred Iand
1111Ul111hired 11op is. as a rl e. much ore pr )olln iliet : lil how vefr
careful the gi'r er miglit Ibe to harve-t his rop at I the stage oIf
maturity bet 'ale latel to give thei greatest iniifrmitiv in color. it is
evident that in liiarketing i protihwt lie wihl hIavte to -''ek for those
olnsmler's w ho have a l(pferenc'e for t it- gr10 ieenh i r ds of lo .
Frold the re-iilt of the hiWniial test- it is aplalt'lt that 11-su-
phuredl hlops are he-.S Suited to the rquirment- otf the con- o uer than
those that have Ibeen stilphured. e-pecially when they are tmreti for a
considerale length of time before they are use(l. H however, the fact
should not he lit sight of that these tests were madi' on hips which
had )been inl toage for illore thaii t wo vear:. atlli the M'hint1/ o)-
served are ('certaildv (on-id erably greater ithan ilAtt e which ot'l'r ill
hops which have iei store I for a shorter period. Neverth ele-. the
greater part of the chlianlges in certain co (stitueint I takl- place during
the first vear of tora. as ha een hon Ib 11 erom in the cas
of the tanin of Ihops. But from thle w ork of Nlocr,' who found
that the talniin colltent of unuII i) tl sampi Wle Ws (' ItmP- il yv
Smaller tha in that of -u )llihel -ailpe- OfI the >a1 11e >4f-, it i- eV il!
that the oxitlation of the tanin is ret atled by -l hudiuring. It may
IStockberger. W W Th. so.ur* of ar- ni ino **rti tn *.Puphs of stri..l hop- 1Iili*
tin 121, pt 4, litar'.tta f I'l.it lhaItry S. t of \;zrioslit rs' 1V**
2 leron, .ohin. IT t r'ui, of hstops .10IH I of I' dh 1' rA td Institutes of Ill w ing.
vol 2, IMi p. 172
SCited by Braungart in Der ilopfe n. Muni h. 1001, p. 84U.
271




20 SOME EFFECTS OF REFRIGERATION ON HOPS.
be safely assumed, however, that sulphuring is an effective means of
retarding chemical changes in hops from the time they are cured until
they have reached the desirable limit of age, usually determined by
commercial conditions, provided such hops are held in cold storage.
It is fully realized that the conclusions drawn in this paper are
subject to the criticism that the analyses are too few in number and
that they are not coordinate in point of time with each other and
with the physical valuations. Certain obstacles encountered in the
course of the work made it impossible to round out the results as
fully as was desired, yet it is believed that the coordinations sug-
gested by the facts developed are of sufficient importance to justify
this somewhat incomplete presentation, which should be regarded
more as a report of progress than as an attempt at a full elucidation
of the problem, for which much further experimentation is necessary.
SUXMARY.
Material for a comparative study of the effects of cold and ordinary
storage on sulphured and unsulphured hops was secured from a hop
field in the Sacramento Valley, Cal. The green hops were divided
into two lots, only one of which was sulphured during the process of
drying. Bales from each lot were placed in cold and in ordinary
storage, and samples from these bales were drawn from time to time
for examination with respect to physical condition and certain chemi-
cal constituents.
At intervals of 7 and 18 months, respectively, from the time the
hops were placed in storage, samples were drawn and submitted to
trade experts, who were asked to rate the samples according to their
relative quality. All agreed that the sulphured hops in cold storage
were best in quality, but opinion was divided as to the relative merit
of the three other lots.
Determinations were made of the acidity and ester content of the
volatile oils extracted from samples of the hops under each condi-
tion of storage. The conclusions drawn from these analyses are that
both sulpburing and cold storage retard changes in the hops leading
to an increase in acidity and ester content of the oils. Cold storage
is apparently more effective than sulphuring in retarding the increase
in acidity, but is less efficient than sulphuring in retarding increase in
ester content. Cold storage and sulphuring combined are much more
effective in retarding changes in acidity and ester content than either
alone.
The percentage of decrease in the content of soft resins was less
in the cold-stored hops than in those in ordinary storage. The evi-
dence from the analyses goes to show that the sulphuring ten& to
271




8s U 4 MNIARY. 21
retard changes in the mnatent of soft rein"s only alwn combined with
cold storage.
rad(e eXperts to H whI san58h of the hoI undsler c4lirati il
were submitted for physiedal jiudgiment liffered widely iln theitr nn
ions of relative merit. except in th( le case of the sulphuared col stowI l
hops, which all agreed ranked first. The relative ratnk i mheit a:
determined fronml each of the factors sought in anal V:is wVas foumlol
to give corresponding differences A comparison of these ditffervt.,-
in tIe physical and l eWial al 1a1ltion shoWs that he dtertiPllimt lI
of the valte of hops from the aroma depemdls upon the persm'oal
taste of the olh erer ani is greatly afl0ect4l by Ithe in liviluals pm-f-c
erence or dislike of one or the other of the several constituents of tLhe
a Frema.
us"010
271
O







Cl ax"44




u NIVI:RSITY OF FLORIDA
3 1262 09216 2154
40-0