Effect of Agronomic and Storage Practices on Raffinose, Reducing Sugar, and Amino 1
Acid Content of Sugarbeet Varieties
R. E.
WYSE AND
S. T.
Received fo,- /Jub licati on July
DEXTER 2
IO.
1970
Introduction
The decrease in bagged sucrose per ton of beets during stor­
age results primarily from two factors . Sucrose is respired, evolv­
ing CO 2 , The transformation of sucrose and other beet con­
stituents into raffinose, reducing sugars, amino acids, etc., re­
sults in an accumulation of non-sucrose solutes in the thin juice
and corresponding increased sucrose losses into the molasses.
Reducing sugars, raffinose and amino acids account for a major
portion of the fluctuation in impurities during storage (Wyse
et al.) 1970). The purpose of this study was to determine the in­
fluence of harvest date, nitrogen fertilization and storage tem­
perature on the content of these three impurities in several
sugarbeet varieties.
Reducing Sugars
The predominant reducing sugars in the beet are glucose and
fructose. Free galactose and arabinose are found only in trace
amounts (Silin, 1964). Reducing sugars are presumably destroy­
ed during lime defecation and occur in very small amounts in
beet molasses (McGinnis, 1951; Silin, 1964). In this process the
reducing sugars are degTaded to acids (lactic, formic , acetic, sac­
charinic) (Carruthers et al.) 1959) which must be neutralized
by the addition of sodium carbonate before evaporation to re­
duce soluble lime salts and to prevent sucrose inversiop (Silin,
1964; McGinnis, 1951). As a result of the addition of sodium
carbonate, molasses quantity and purity are increased resulting
in increased sucrose losses (Si Jin, 1%4).
The reducing sugar content of beets at harvest is normally
very low and sodium carbonate addition usually is not required.
However, during storage invert sugar may increase drastically,
particularly if mold or rotting occurs (S tout, 1954; 'Walker et al.)
MiChigan Agricultural Experimen t Station Article No. 5 118.
Formerly Grad uate Assistant, Department of Crop and Soil Sciences, Michigan State
University; presenlly , Plant PhYSiologist, U.S. Department of Agriculture, Crops Research
Division , Logan , Utah. Professor Emeritus, Department of Crop and Soi l Sciences, Michigan
Statel:nivcrsity.
This study was supported in part by the Agricultural Research Service, U.S. Depa rtment
of Agriculture, Cooperative Ap;ree ment No. 12·14-d476 (34) adill inistered by the Crops Re·
search Division , Beltsville, Maryland.
1
2
370
JOURNAL O F THE
A. S. S. B. T.
1960). Even under storage conditions which prevent molding,
sprouting, and wilting, reducing sugars may accumulate, parti­
cularly at storage tem peratures above 10 C, because of changes
in the me tabolic balance in the beet root (Walker et al.) 1960).
This accumulation is accelerated by storage conditions which
allow desiccation of the beel root (/\tterson et al.) 1963).
Raffinose
T he major trisaccharide is raffinose 'which usually occurs as
0.3 to 0.5% of the sucrose present (McGinnis, 19::>1). The amount
increases with prolonged cool periods during gTowth or storage.
Raffinose is as chemically resistant to lime defecation as sucrose
and ther efore accumulates in the molasses. Raffinose is a parti­
cular pro blem in th e Steffen process where it accumulates to
high levels in the thick juice. A high raffinose content in the
thick juice may prod uce distorted and elongated sucrose crystals
as weli as reducing the rate of crystallization (McGinnis, 1951).
T he level ot raffinose at harvest and the degree to which it
accumu ,ates during gTowth and storage are varietal character­
istics. Several populations of mass selected beets were shown by
vVood ::t al. (1956) to vary by 10-fold in raffinose content. Five
varieties storeCl for 29 'weeks at 4 C sho'wed a significant variety­
storage interaction.
T he effect of temperature on raffinose accumulation was il­
lustrated by sLoring beets 0.t I C and 12 C (Walker et al.) 1960).
A t 1 C the raffinose content increased four-fold after 60 days
and then declined with prolonged storage. At 12 C the raffinose
content almost douoled but then remained essentially constant.
The effect of temperature was found to be reversible since beets
allowed to accumulate raffinose :It 2 C for 120 days when shifted
to 25 C storage for 25 days, declined almost to their harvest level
(McCr eady and G oodwin, 1966).
Amino Acids
c.i'he amino acids contribute to lime salts in the factory and
can cause a substantial pH drop during evaporation through
deamination (Silin, 1964).
The amino acid content of the beet root is primarily a func­
tion of nitrogen fenilization (H addock, et al.) 1956; Hac et al.)
19,:)0). GluLamic acid, the dominant amino acid found in the
beet root, appears to be a very sensitive indicator of the nitrogen
fertili ty level and consequently has shown a high negative cor­
relation 'with th e sucrose content of the beet root (vVoolley and
Bennet, 1959; vValker et al.) 1950; Hac et al.) 1950). Excessive
nitrogen ferti lization also caused an increased accumulation of
other non -sucrose substances re~ulting in a decreased purity
(H enry et al.) 1961; Haddock et al.) 1956). Although a significant
VOL.
J6, No.5,
APRIL
1971
371
variety-nitrogen interaction is commonly found, the nitrogen
effect is by far the most dominant in amino acid production
(Finkner e t al.) 1958; Henry et al.} 1961).
Materials and Methods
1967 Experiments
The beets in 1967 ,"vere grown in replicated plots near Se­
bewaing, Michigan. ' In the fall of 1966, 375 pounds of 0-0-60
was broadcast and p!owed down . Just prior to planting, 900
pounds of 0-20-0 was applied hroadcast and incorporated with
a field cultivator. On \1ay 3, 1967, the beets were planted in
28-inch rows with 200 pounds of 12-6-6 applied as starter ferti­
lizer. After thinning to 120 beets per 100 feet of row, the beets
designated as high nitrogen were side-dressed with 120 pounds
of nitrogen per acre for a total of ISO pounds of applied nitrogen
p er acre. The beets with low nitrogen received only the 24
pounds p er acre of nitrogen applied as a row fertilizer at the
time of planting.
The five varieties and their quality ratings based on a com­
bination of sucrose, clear juice purity (CJP ), and yield are given
below:
Variety
number
1
2
3
1
Variety
SP5481-0
SP6 3194-0
02 Clone
SP6322-0
lJSH20
Type
Multigerm
Monogerm
Multi germ
Multigerm
Current
Commercial
Hybrid
Monogerm
Quality
rating
Average
Poor
Good
Excellent
Excellent
Harvests were made on O ctober 6, October 26 and :K1ovember
6, 1967. All fiv e varieties were. harvested on October 26, but
only varieties 2, 3, and 5 were harvest ed on the other two dates.
Beets from six fi eld replications were pooled at harvest and
lightly topped to remove the terminal bud . The samples were
trans:,orted to the Vfichigan Sugarbeet Research Laboratory in
Saginaw for analysis and storage.
1968 E x periments
Beets of variety 5 were grown near St. Charles, Michigan,
in 1968. The only fertilizer applied ""vas 500 pounds of 6-24-12
at planting. The beets were thinned to 120 per 100 feet of
" These beets and th e yield data at harvest we re obtained wi t h the coopcratiot: of Dr.
Rich a rd C. Zielke.
372
JOLRNAL OF THE
A. S. S. B. T.
row, four wecks after p lanting. They were harvested on Septem­
ber 1, October 1, and November 1.
Additi on al beets of the three varieties shown below were
harvf'sted on lovember 10, 1968 , from the breeding nursery
a L the \IIichigan Agricultural Experiment Station.
Variety
number
5
6
7
Variety
US H20
SP 6721-01 ms
SLl20 X CI4661 X CI4661 ms
.\£Ler washing lVith hig-h pressure cold water, the pooled
field samp:f's we re sorted by specific gravity (Dexter, et at.) 1969).
After sorting, the beets were rinsed to remove any adhering
sodium chloride and, after curLace drying, were made into 10
beet samples of uniform weight for storage or immediate ana­
lysis. All samples were stored in sealed 10" X 11" X 28" poly­
ethylene bags. Each sample bag contained a one-pint perforated
polyethy:cne bag con taining wet wood chips to saturate the
atmc:; phere and thus prevent wilting. All treatments except tem­
pera ture were replicated four times.
At the time of each analysis, clarified juice was prepared by
the method of Dexter et al.) (1967). The concentration of raf­
finose, reducing sugars, and amino acids in the clear juice were
d etermined using galactose oxidase, 3.5 dinitrosalicyJic acid, and
n inhydrin , respectively, as reported previously (Dexter el al.,
1969; Dexter et al. ) 1970a).
Results and Discussion
Raffinose
T he raffinose content of beets durin g storage was very tem­
per ature sensitive. In 1967 variety 5 was stored at four tem­
peratures ranging from 2 to 12.8 C for 3J, 70, 105, and 145
days. At 4.5 C the raffinose content remained essentially con­
stant and declined at all higher temperatures (Figure 1). To
avoid raffinose accumulation, the optimum storage temperature
for this variety appeared to be slightly ahove 4 C.
Five varieties 'were stored in 1967 to determine the variety
effect on raffinose. :\t harvest there was a small but significant
difference between varieties (Figure 2); however, after 65 days
of storage at 3 C, the range between varieti es increased to 1400
mg/ kg. Varieties 2 and 4 accumulated considerably higher levels
in the first 65 days of storage than the other three varieties. Ra f­
finose declined in the last 65·day period for all varieties except
variety 3 in which the raffinose increased linear ly over the entire
storage period.
VOL.
16, No.5 ,
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373
197 1
2000
1800
1600
1400
,
~
~
~
1 200
oi
8
.5
1000
800
600
400
200 ~----~------"-------L----~
35
70
105
145
S t orage Period, D;JYs
Figure I.-Effect of storage temperature on the raffinose content of
variety 5 stored up to 145 d ays in 1967 .
,
.-<
IE
"'"
0
0
"
5
'"'::
2600
2400
'"
Storage Period, Days
Figure 2.-The raffinose conten t of five varieties during storage at
3 C in 1967. All beets were harvested on Oct. 26. Variety: 1, 0; 2, 0 ;
j,~;4,.;5,*.
374
JOURNAL OF THE
A. S. S. B. T.
Raffinose was very high at harvest in 1967, apparently as a
result of cool, damp weather during October. Prior to harvest
on November 6, a severe frost caused visible freezing injury to
some of the beet crowns. The average raffinose content of three
varieties (2,3,}) increased 35% from 1300 to 1850 mg/kg be­
tween the October 6 and the ~ovember 6 harvests (Figure 3).
During storage at 3 C beets from all harvests reached approxi­
mately the same level after 6:) days.
3100
o ctober 6
2500
I .
October 26
2100
1700
1300 ' - -_ _ _ _ _1...._ _ _ _---'
65
130
Storage PC!riod, Days
Figure 3.-The effect of harvest date on the accumulation of raffinose
during storag~ at 3 C in 1967. The data [or each harvest date is the average
of varieties 2, 3 and 5.
The very high raffinose levels at harvest and during storage
in 1967 caused a considerable error in the percent of sucrose and
in the CJP determinations resulting in an overestimation of
the recoverable sucrose per ton (RSPT). These results indicated
the need for correcting the percenl sucrose and CJP determina­
tions of stored beets, and of harvested beets for some years
(Dexter, et al.) 1969b).
~ itrogen fertilization had no effect on the raffinose content
of the roots either at harvest or after storage (Table 1).
The effect of harvest date was again studied in 1968. The
weather during the fall was warm and dry resulting in a lower
raffinose content at harvest compared to the previous year (Figure
4). However, the raffinose content attained in storage was com­
parable in the two years. As in 1967 the less mature beets show­
ed the greatest increase in raffinose during storage. The gen­
VOL. 16,
]\io.
5,
;;75
1971
/\PRIL
Table ] .-Nitrogen X removal interaction for raff inose accumulation in storage in
1967. Data are a,erages o( 3 ,rarielies a nd three harvesl dates.
Nitrogen
Storage period, d ays
At
harvest
65
Average
130
i'vI g Kg·- t
1bs/A
24
1749
:;U17
150
1778
2954
ns----non-significant at the
5 ~o
229~
2 127
2675
ns
211;9 ns
level
eral decline with prolonged storage observed in 1967 occurred
only in the case of the late harvested beets in 1968.
october 01
3200
sep t e~ r 1
2800
2400
If'
2200
2000
1000 (
600
I
f!
50
100
S t o r ~ge Per iod , Days
Figure 4.-Effect of harvest d ate on the accumulation of raffinose
variety 5 during storage at 3 C in 1968.
111
Three varieties were stored in 1968 at temperatures above
and below th e presumed threshold level of 4.5 C (based on
variety 5, 1967; Figure 1) for raffinose production. Varieties
6 and 7 in 3 C storage increased 2800 and 3200 mg/ kg respec­
tively while variety :5 increased only 1600 mg/ k g (Table 2). This
correlates well with the varietal differences found in 1967.
Table 2.-Influence of temperatu re in the production of raffinose by three varietie>
during storage for 100 tl ays a t 3 and 10 C (1968).
Variety
At
harvest
Storage tempera ture, C
3
10
iVlg Kg-l
5
6
LSD .•, among means-28 1 Mg Kg· l
1286
2212
1694
2966
800
5014
4865
2700
1798
376
JOURNAL OF THE
A. S. S. B. T.
The raffinose content of variety 5 at 10 C declined while
varieties 6 and 7 both increased. The response of variety 5 was
consistent with the 1967 experiment which gave a threshold of
4.5 " for this variety. In this experiment the threshold for var­
iety 5 may have been a few degrees higher than in 1967 since
the raffinose content did not decline to the low levels found
for the 7-12 C temperature range in the previous year. How­
ever, the threshold temperature appeared to be a rather con­
sistent varietal characteristic. Varieties 6 and 7 had a much
higher threshold temperature, possibly as high as 15 C for var­
iety 6. The very high levels of raffinose accumulated in storage
would make varieties 6 and 7 questionable candidates for com­
mercial use.
The theoretical sucrose loss resul ting from the production
of raffinose is not as great as that for reducing sugars but is
still substantial. One pound of raffinose is derived from 1. 36
pounds of sucrose, assuming the galactose is produced originally
from sucrose. This pound o( raffinose will also carry 1.67
pounds of sucrose mto the molasses, assuming a 62.5% molasses
purity, for a total loss of 3 pounds.
Reducing Sugar
In 1967 beets of variety 5 were stored at three temperatures
(4.5, 7.2 , and IV)) for up to 115 days. In the first 70 days of
storage there ,vas no significant change in the reducing sugar
content at the three temperatures (Figure 5). Beets stored at
12.8 C began to sprout after 70 days , and this may account for
the rapid increase in reducing sugars. Beets stored at 4. 5 C
had some small spots of mold which developed in the cut sur­
face of the crown area as a result of excessive moisture condensa­
tion. This would account for the rapid rise in reducing sugars
after 105 days of storage. The beets stored at 7.2 C remained in
4.5 C
2100
,
~
~
1700
0
0
i
~
"2. ", C
1300
7.2 C
!
~
9 00 ~ 500 ~o--""1'+-5--......f:70:---~lO!:-5---:o!145
Stor age
p c ~i od .
Da y s
Figure 5.-Effect of tempera ture on the accumulation of reducing
sugars in heets stored for up to 145 days in 1967.
VOL.
16, No.5,
377
197 J
APRIL
excellent condition with nt'ith er mold 'lOf sprouting, and the
increase in reducin g sugars was correspondingl; small.
Five varieti es stored at 3 C for 65 and 130 days 111 1067
showed substamia l acc umul a tions of reducing sugars 111 only
65 days Cfable 3) . ] [owevcr, the occurence of small ar eas of
mold was common in the cut area of the crown around the crown
cavity. Although thes e areas were very small, they were ex treme­
ly high in redu cin g sugars and tbus increased tbe average re­
ducing sugar content of the entire root. Altbough substantial
differences were found between varieties, the vari ab ility intro­
duced into the experiment by the small amounts of mold made
it impossibl e to draw conclusions concerning varietal charac ter­
istics.
Tabk
3 .- A~::::: imul a tion
of rcduciH..j" sugar jn nvc val'ieties s l:-, red (or 65 a nd
J30
da ys at 3 C in 1957.
At
harvest
Variety
StoT;)ge period, da ys
65
130
~rg
4
5
.\ve.
LSD."" [or remol'al means
Kg -l
1)60
1040
Bri9
611
G5G
15 13
799
1144
783
2394
7:21
] 378
3711
2649
2736
2607
2260
2793
8) 9 Mg Kg ,
The redu cin g sugar content of tht' beets decreased slightly
during the 1967 harvest period. During storage, the increase
in redu cing suga rs was highly significant Cfable 4). The oc­
currence of very high l eve ls of reducin g sugar after 130 days re­
flects th e mold situation discussed previo usl y. In ge ueral the
beets harvested early, although higher in reducing su gars at
harvest , accumulated reducing sugars only m oder atel y in stor­
age at 3 C. The same trend was observed in 1968 wht'n no mold
developed in storage (Figure 6).
Table 4.--H a rvcst )( relnoval interaction for reducing suga r accumulation ( 1967) for
beets stored at 3 C. nata are the a\'erages of 3 varieties a nd 2 N lev els.
Harvest
date
At
harvest
Octobe,' G
Octob er 26
77]
765
No\'elnber 6
fi95
Sto rage pniod, days
65
130
Ivfg Kg- l
944
]203
]084
) ]7 5
2549
2994
LSD.Oj among m ca ns-303 ;Vlg Kg"
Nitrogen fertilization had no effect on the reducing sugar
content of the r oo ts at harvest or after storage.
A hi ghl y significant variety- temperatu re' interaction for re­
ducin g sugar accumulation occurred in 1068 when samples of
378
JO U RNA L
OF THE
A.
s. s.
B. T.
1400
Nove~r
1
1200
-:
~
..
.
Septe mber 1
''""
"
if '" 1000
.5u
~
0
"0
&
800
7 :
6 00
50
100
<; t orage Per i od . Days
Figure 6.-Effect of harvest date on th.e accumulation of reducing
sugars in variety 5 during storage at 3 C in 1968.
three varieties were stored at 3 and 10 C (Table 5). No mold­
ing occurred at either temperature. The accumulation of re­
ducing sugars was very small for all varieties stored at 3 C, but
they increased subctantially in all varieties at 10 C. The sen­
sitivity of the varieties to 10 C storage was different. Variety 5
dou bled in concentration of reducing sugar, whereas variety 7
increased only 35% .
Tab!e 5.-InteractiO'!l of variety with temperature in the accumulat·ion of reducing
sugars afler 100 days o[ storage at 3 and 10 C (1968).
Variety
5
6
Avera ge
LSD.o;:; among Jne;ll1 s-227 j\lg Kg'
At
harvest
fi56
916
831
801
Storage temperature, C
10
3
Mg Kg-l
658
1095
965
906
1297
1530
illS
1314
The high leve!s of reducing sugar in the stored beet appear­
ed to be largeiy the result of mold. Temperature effects were
prirrarily manifested as secondary through sprouting and mold
invasion. However , the results in Table 5 indicate that variety
may be important when mold is eliminated. Variety:J remained
low in reducing sugars both in 1967 and 1968 when molds were
absent (See Figure 5 and Table 5). It may be possihle to select
VOL.
16, No.5,
APRIL
379
1971
varieties which can tolerate storage aGave 5 C without a signifi­
cant production of reducing sugars in the absence of molding.
Reducing sugars, in the abse nce of molds, can be produced
by rwo enzymes, invertase or sucrose synthetase. Invertase ac­
tivity in the beet is normally very low, but the activity is suffi­
cient to support respiration (vVyse, 1969). Sucrose synthetase
in the root is also capable of producing reducing sugars from
sucrose. Sucrose synthetase has a K eg of approximately 1.3 which
indicates that it is easily reversible and may be an important
source of sugar nucleotides and reducing sugars in the root
(Milner, 1964; vVyse, 1970).
Invert sugars are degTaded to acids during lime defecation
and as a result, are particularly important in the study of storage
losses. Many of these acids have soluble ca lcium salts which re­
quire neutralization with sodium carbonate. If sufficient sodium
carbonate is added to neutralize all the acid produced from one
pound of invert, 4 pounds of sucrose will be los t. This is a re­
sult of a I Ib loss by inversion and a 3 ib loss to molasses re­
sulting from sodium addition (Dexter, et al .) 1970b).
Amino Acids
Beets grown with 24 Ib/ A of applied nitrogen became ni­
trogen de ficient (light gTeen leaf color) several weeks prior to
the October 6 harvest in 1967. Plants which received high ni­
trogen, 150 Ib / A, were still succulent and green at the first
harvest date, October 6. The free amino acid content of the
roots of plants on low nitrogen decreased almost linearly dur­
ing the harvest period (Figure 7, dotted lines). The free amino
Oc t ober 6
3600
~
3200
..
'"~'"
2800
w
2400
'3
u
'"
0
52.
2000
'"
1600
oct obe r 26
Novembe r 6
~. ~~ ........ .. ..... ~.. .. ,,~,.
........... ...
.....
. ~ ..
"\;
"~,, ~"~
.....
.----,~,. ~o,~" ~~~.
____u
1200
65
l3 0
o
65
130
Q
24#/A
65
130
Stor ag e Pe ri od, Da ys
Figure 7.-Harvest X nitrogen X removal interaction for a mino acid
content in beets sto:'ed a t 3 C for 65 and 130 days (average of varieties 2,
3 and 5) .
380
JOUR'\,\L OF THE
A. S. S. B. T.
acid pool in the root was apparently being depleted as a result
of the nitrogen deficiency, Beets grown on high nitrogen re­
mained high in free amino acids until October 26 after which
they declined rapidly. On November 6 the beets grown with
high nitrogen had the same amino acid content as the beeLs
grown with low nitrogen and harvested on October 6.
The amino acid content declined in storage at 3 C. This
has been reported previously (Dexter et aZ. ) 1966 ; Silin, 19(4)
and is apparently a result of the synthesis of new enzymes and
other proteins. The beets grown with low nitrogen declined
rapidly in amino acid content and then appeared to reach an
equilibrium level at 1200-\500 mg / kg. The beets with high
nitrogen declined almost linearly in amino acids throughout
the storage period. The five varieties stored for 65 and 130
days showed neither a significant variety-storage nor a variety­
nitrogen·storage interaction. However, the variety-nitrogen inter­
action at harvest ,vas highly significant (Table 6). On the aver­
2ge, the increased application of nitrogen caused a near doubl­
ing or the amino acid content in the rool. Variety 5 a ppeared
to be highly sensitive to nitrogen fertilization since its amino
acid content increased the most with the higher nitrogen aT)­
plications. This sensitively was also apparent in reduced RSPA
with high levels of applied nitrogen (Wyse, et aZ.) 1970).
Table 6.-Variety X nitrogen interaction in amino acid content of five varieties har­
ve'ted on Oct. 26, 1967.
Variety
Nitrogen applied, Ibs/ A
24
150
Mil' Kg-l
1
2
3
4
5
Average
164-3
1454
J609
1322
1541
1514
2153
2493
3036
2113
3564
2783
LSD.o, among means-355 lvlg Kg··
In 1968 three varieties stored at 3 and 10 C reacted vcry
differently to temperature in terms of their amino acid content
(Table 7). Variety 6 was extremely high in amino acids at har­
vest and accumulated substantial quantities at both storage tem­
peratures. The high level of amino acids in this variety would
apparently make it undesirable for commercial use. At ?l C
variety 5 declined as it did in previous experiments (Dexter,
et aZ.) \966). However, the amino acid content of variety;) was
very sensitive to high temperature storage. Variety 7 was low
in amino acids at harvest and did not acc umulate signific;.mt!y
at either temperature.
VOL. 16,
~<!).
5,
Ap l-:. IL
1971
381
Table 7.-The fi'f('ct of storage ternperature en
stored for ]00 days in 1%8.
the amino acid content o [ bee ts
Storage tcmp(':l"ature, C
Variety
Harvest
3
10
~l g
5
6
7
Avcrag'e
12 i 1
nm
808
l'f39
[1 28 ( Il 3)'
2567 ( ;- 300)
S64 (; 56)
1520
Kg -'
1705 ( + 464)'
2749 ( + 482)
%9 ( + 16[ )
2[[7
a Parent heses inJi c<1te change during storage .
LSD.o.; amo ng means-3SS Mg Kg· ·
Summary
The accumulation of raffinose in sllgarheel roots during
growth and storage was primarily a function of temperature, in­
creasi ng with lowerc:d tem perature either in the field or during
storage. The thrfshol d temperature for raffinose accumulation
10 rools during storage "' 2: 5 approx imately 5 C, but this varied
somewhat between years and gTeatly between varieties. Hefts
harvested in September and early October were lower in raf­
finose content than beets harvested late, but the beets harvested
early accumul ated more r affinose in storage. :\litrogen fertili za­
tion had no effect on raffinose content at harvest or after storage.
Reducing sugar accumulation in roots was accentuated by
mold. Huwever, the vari e ty-tem 'Jerature interaction for reduc­
ing sugar accumulation was highly significant 'when m old and
nro utin g were eliminated. In the absence of mold , reducing
sugar increased more in higher tempnatllre (3 vs 10 C) storage.
The amino acid content of the beets was primarily a func­
tion of applied nitrog'e n. The vJriety-nitrogen interaction was
highly significant at harvest but not after storage. Most varieties
stored at 3 C generally declined in free amino acids. All var­
ieties accumulated approximately 30 % more amino acids when
stored at 10 C than ,\Then stored at 3 C.
Vari etal cons istency from year to year could not be demon­
strated conclusively because only one varie t y was studied in
more than one year. However, this variety did show very con­
sistent trends for all three rnajor impurities.
'With the exception ot the amino acid con tent, less than ideal
storage practices were found to have a muc h greater effect on
the chemical co mposition of beets than did agronomic practices.
In storing beets at various temperatures, varieties differed con­
siderably with respect to the level of raffinose, reducing sugars ,
and amino ar:icts in the clarified juice. Since these comDounds
make up th e major proportion of the non-sucrose constituents
of th e clear juice, it 'would appear that the level ot these im­
purities could be controlled throu gh variety improvement and
382 JOURNAL OF THE A. S. S. B. T.
proper agronomic and storage practices . The development of a
variety which would tolerate storage temperatures in the 7 - 10 C
range without the accumulation of reducing sugars or amino
acids, assuming that sprouting is prevented, appears to be feasible
and would greatly reduce the problem of storage temperature
control.
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