B vitamin content of sugar beets and sugar beet by-products

The B Vitamin Content of Sugar Beets and Sugar Beet By•Produots.1 Dexter Rogere2 and

K.

N. Kickelson3

(From the Hygienic taboratory, University of Michigan, Ann Arbor)

!·t I:,

As part of a--projeot to 11:1v~stigate the utilization of by-products of the sugar beet industry by microbiological means, a survey was made to determine the amounts of B vitamins in these materials. The term "by-products" of the sugar beet industry as referred to in this report includes such materials other than sucrose which result when the sugar beet is processed for its sugar content. Details of sugar manufacture from sugar beets, including a flow sheet, are avail-able .in Rogers Manual of Industrial. Ohemistry(l). Some of the materials exami11,ed for their vitamin content, for instance, diffusion juice and green syrup, could mo~ properly be considered as intermediate prodpots which result in the refining process.

Beet molasses is a viscous dark brown syrup of about 60 per cent sugar o~tent which remains after removal of the crystalline _{~· "h} euorose. It is analagous to blaokstrap molasses of the sugar cane industry. Steffens waste is the waste wa~r from the Steffens House poceas of recovering suor-ose from beet molasses.

The crown is the top l to l 1/2 in. of the s'ugar beet which is unsui

t-able for processing into sugar because of' its hlgh salt content. _{The top of the} plant is the green, above ground portion of the plant differentiated into stalks and .leaves.

1This work was aided in part by a grant from th& Farmers. and Manufacturers Beet Sugar Association, Saginaw, Kichigan. '

2_{Present Address, Western Condensing Co., Appleton, Wisponsin.}

There is considerable interest in the beet orown as a potential source of chemical prod.uots by fermentation processes. In Michigan at the present time. the orown is discarded in the field during harvesting. Though some of it is eon-sumed as forage. it is not an ideal dairy feed._.. Recently it has been proposed that this portion of the sugar beet be oolleoted, slioed and dried. or made into a syrup which would serve as a source of fermentabla carbohydrate. Certain stud.ies have been oarried out along these lines and the data will be reported elsewhere.

The beet seed ohatf is a portion of th~ sugar beet seed whioh results during a process of meohanioally separating the multiple germ seed into its units. Several million pounds of this material are produoed annually.

Lime cake is a by-product whioh results during the treatment of the dif-··-~

fusion juice with Ca(OH)2 to remove inorganic ~purities and aid in clarification. The above mentioned materials have been analyzed for their content

ot,

,,

B~itatnins by the use of microbiologioal assay procedures. The vitamins for which ana:tyses were made were thiamine, riboflavin, ~l,'.potinic acid, pantothenio aoid• biotin, phridox~.ne and "folio acid." It was felt that in.fom.a.tion acquired by this study might be of value for the following reasons c (1) 'l'he introduction or the use or ion exchange resins in the sugar beeu industry (~ 8) and their more recent

application for recovering thiamine and ribofl,a~in

(4)

which suggest a praotieal me~s of recovering the vitamins from the ·sugar beet during prooessingJ (2) The _•·'·I· use of sugar been by-products as substrates for fermentation processes, whioh re• qui~e an adequate quantity of growth factors.

For comparison. several products and by-products of the sugar cane in• dustry were included in this study, namelyJ ·beet molasses, high invert syrup and a oommerqdtil sample of table grade cane syrup ...

steep liquor was also inoluded.

A sample of concentrated corn

I I

i

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EXPERIMENTAL

Samples of the sugar beet with tops attached were received at the laboratory as soon as possible after harvesting. They were washed to remove the soil and

representative portions of the whole beet, beet crown and beet tops were stored in a deep freeze unit at

.50•c.

until such time as they could be analyzed. Diffusion

juioe and Steffens waste were received in glass bottles from the mills and preserved by the addition of l per cent chloroform and storing at 6°C. until used.

The high green syrup, beet molasses, plackstrap molasses, cane table syrup, invert syrup and concentrated corn steep liquor.were kept at room temperature. Sugar beet seed chaff was finely ground in a manually operated burr mill before extraction.

The specimens were prepared for assay as followa1 A portion of the frozen or dried plant tissue was we,:l.ghed and then oru~J1ed in a mortor with aP,dtle. '?he tissue _{,, ..} was transferred to a Potte~·Elvehjem glass homogenizer<5 ) and ground in dis-tilled water. Next an enzyme was added or the material treated with 41lute acid at

'

12o•c.

in an autoclave for 16 minutes to release the vitamin from its bound form. After filtration to remove extraneous tissue the filtrate was diluted to volume and •. 'f.• aliquot portions used for analyais. Where necessary the samples were extraoted with ether before making to a definite volume in order to overoome interference by fatty

aoida in the vitamin assay prooedure(l2 ). In preparation of the liquid material•

the' same general procedure was followed except that it was only neoeasary to dilute with

·,

wate-r before treatment to release the vitamin. Since the chaff from the ~eed waa high in folio acid the germ portion was removed from the seed and analyzed separately to determine if it was richer than the rest of the seed in this factor. ,! ~

The particular microbiological method and pretreatment applied to eaoh sample is indicated in Table I. ·The standard ourvea in all but the folio acid aasay were obtained with pure crystalline vitamin,. After careful drying, solutions of known

vitamin content were prepared against whioh the unknown samples were compared. The folio aoid standard was prepared from a solution. of crystalline vitamin

a,.

•Kindly supplied by Dr. J. J. Pfif:f'ner of Park-Davie and Oampaey

I

It was necessary to modify the procedure for thiamine assay in order to get suitable standard ourves. The sample of Difeo peptone available could not be

adequately freed of thiamine according to the procedure used by the authors.

The

modification oonsisted of bringing the peptone solution to a pH of 9 with NaOB and auto-olaving for 30 minutes at 12o•c.

the reoommended oonoetration.

It was then adjusted to pH 7

.o

and used in one halt'

The assay values given in Table II are the average of several 4eterm1nations of three dilutions and represent the micrograms of vitamin per gram of original material.

The graph• or Figure I were prepared from information available oonoerning the volume of eaoh of the by-products whioh result per unit of sugar beets during the

beet refining prooess.

DISCUSSION

If one separates the sugar bee~ plant into the leaves and stalks whioh maa up the top, the crown or upper l to l 1/2 inoh of the beet. and the beet tissue pro• per, whioh is pooessed for its sugar content. the relative distribution of B vitamins

in the sugar beet plant is as followat

Leaves') stalk8

>

"crown."

>

tiHue

Since the tops of the plant have the lowest "solids" content, this progression from the leaves to the beet tissue would become pronounced if the vitamin content was expressed on,a dry basis. This finding was not wholly unexpected since the top portions

ot

the plant are perhapa metabolically the most active,, and especially in view uf the faot that some of the members of the B-oomplex are known to be integral parts of enzyme molecules. There are, however, a few exoeptions to the above staten:ent. The stalks con• tain less thiamine than the "crown" and beet tissues. The beet "crown" has also a higher content of niootinio and pantothemio aoids tl'j.an the stalks and is equal to it in pyrido:xine.

beet tissue.

However, the leaves contain more of etoh of the vitamins tested than the

!

The beet molasses compares equally

well

with "high test" molasses (oane invert \

syrup) and the table-grade oane syrup in most respects, but is lower than "blaokstrap"

molasses except for nicotinio acid and urolic acid." Except for "tolio acid", "'corn

steep liquor" has a higher content of the B vitamins than any of the sugar beet by• products assayed with the exception of the seed ohatt. The chaff of eugar'beet seed

is equal to "corn steep liquor" 1n most of the factors determined, and exceeds it in pantothenio acid and "folio aoid." However, it is lower in niootinic acid and shows a de£inoienoy in biotin. The sugar bee~ products are generally lOW'!r in biotin than any of the other materials examined, while they are relatively higher in "folio acid."

The vitamin content of the table grade oane syrup closely parallels that of the cane invert syrup. This might be expected in view of the faot that they are com•

parable with respect to source and oonoentration.

The fate of each of the B vitamins during the processing of the sugar beet

oan be deduced from Figure I. The cirol!J graphs were oona~ruoted assuming the whole

oirole to equal the amount of the vitamin present originally in a unit quantity

ot

the beet

Apparently there are several ways vitamins may be lost during the prooessing

·J-· 1/~

of ;~he sugar beet. The first is the loss due to inoomplete extraction from the beet

tissue, or the loss sustained during the water extraction. The seoond is the lose during concentration and clarifioation of the "d1:f'.fusion juice." This may be due to adsorption otl the ooagulated colloidal material or on the preoipitated lime, or to the e:f'feot of heat and sulfur dioxide treatment. The third is the loss oocurring during

the orystalli,,.ation of the suorose. and is due either to the₁ effects of heating or to adsorption oft the "brown" sugar.

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Thiamine, About 26 per oent of the thiamine -is left u.nextra.lcted in the beet tissue and

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•an be aooounted for in the beet pulp. Of the vitamin remaining 90 per cent is

de-\

stroyed during the oonoentre.tion and clarification of the "d~fusion juioe.," This I

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loss is most likely due to the effeots of the heat and sulfur· dioxide treatment. Only

'

about 6 to 6 per cent of the thiamine remains in the molasses.,,

Ribotlavma About 35 per oent of the riboflavin is lost during the extraction, and this appears to be due ohietly to incomplete extraction. During the clarifioation process 98 per cent of the remaining vi tam.in is lost and a considerable portion can be aooounted for as ad1orption on the "lime oake.•

vitamin remains in the molasses.

Only a small fraction (1 to 2 per oent) of this

Nicotinio Aoidr Essentially a quantitative reoovery of this vitamin is made in the beet molatsea. Obviously, this factor is more stable to physical and chemical treatments than

an;r

of the other factory.

Pantothenio Aoida This vitamin, like riboflavin, is nearly completely destroyed during processing. While part ie left unextraoted in the tissue, most of the loss is due to the ohemical instability of pantothenio aoid.

Biou I Although biotin is found only to a relatively limited extent in the sugar beet,

about 30 per cent of it remains in the molassea. ,t ,,. Losses are due to incomplete extrao-ticm. or to its chemical instability.

Pyridoxines About 75 per cent of the phyridoxine is lost during the water ext~otion, but only a small portion of it oan be found in the beet pulp. Losses are negligible during oonoentration and olaritioation, part

may

be due to adsorption on the "lime cake." Abo~t 2 l per oent of the vitamin is recovered in the molasses•

"Folio Acid" a. This vitamin like pydridoxine is lost to a great extent during extraction, although Olll.y minor losses oocur curing the re~inaer of the processing. Over 26 per oent

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the original "folio aoid11 _remains

in the .. molasses. The germ of the beet seed is no higher in "folio acid" than the other portions of the seed.

SU.MllARY

1) A survey of sugar beet by-products, several sugar oane products and by-products, and a concentrated "oorn steep liquor• for thiamine, riboflavin, niootinio aoid, pyridoxine, biotin, pantoth~nio aoid, and •tolio acid" (vitamin B₀) has been made.

2) In general, the vitamin content of the stalks and leaves of the sugar beet plant was higher than the beet tissue. However, the beet tissue and "orowna" exceed the stalks in thiamine, and the •crowns" are richer than tho·,stalks in niootinio and pantothenio acids.

-Table 1. Preliminary treatments of the plant itssue for assay, and the miorobiologioal methods of assay with bibliographical references.

Vitamin Assayed Thiamine Riboflavin Biootinio Acid Pantothenie Acid Biotin Phyridoxine "Fol ic Acid" Procedure

Sarett and Chelde11n(s)

Snell and Strong(?)

Strong and CarpenterC8 )

Snell and Wright (9)

Krehl, Strong & Elvehjem(lO) Strong. Feeney t)!ld)Earle{ll)

Neal and Strong{ 12

Shull, Hutchings and Peterson<13)

Atkin, Sjhultz. Williams and

Frey\14

Luckey, Briggs and Elvehjem(l5)

Preliminary Treatment

Takadiastase digestion(lG) Autoclaved with O.l ll HC:t, for

15-20 minutes at 120°c.{8J Autoclaved with 1.0 I HCl fqr

15-20 minutes at 12o•c.llOJ

Clarase digestion or autoclaved at( .)

pH 6.8 for 16~20 minutes at 12o•c lZ

Clarase digestion or autoclaved with 3

N H2S04 for one hour at 12o•c(lS)

Autolysjs (17)

Table 2. V1t'1min Content of Sugar Beet Materials and BJt-Produots, Concentrated Cane Syrups and

"Corn Steep Liquor.• (Micrograms per gram.)

Thiamine Niootinie Pantothenio "Folio Acidtt Pydridoxine

{as BCl) Riboflavin Acid Acid (Ca Salt) (Vitamin _{B9 )} (as HCl) Biotin

:....Beet Materials

Tissue 1.0 1.0 2.4 l.9 0.026 1.3

o.ooss

•crown" 1.2 1.3 4.3 5.6 0.051 1.8 0.0013

Stalks

o.s

1.4 3.6 2.1 0.10 1.8

o.

Leaves 2.4 5.5 10.-9 5.7 0.31. 4.4 0.02-3

Seed Chatt 4.6 4.'l 18.0

11.s

1.7 10.4

o.044

Germ

-

l•fi l 5

-

-"Di:ffua ion Juice• 0.5 0.43 1.5 0.82 0.001 0.2 o.0036 "High Green Syrup~

o.a

0.20 36.0 0.75 0.16 2.8 0.022 lfolassee 1.3 0.41 61.0

_.

~-:, 1.3 0.21 5.4 o.053

Dry Pulp

o.ss

0.20 Neg. 0.21 0.18 0.-001

Wet Pulp 8.21 Ifeg. 0.22

-

-

900006

"Lime Cam• Beg. 0.3-0.6 leg. Neg.

-

0.04 0.00013

Steffens

House

Waste

0.16 Beg. 2.0

o.os

0.0014 0.23 0.0022

High Test Molasses 1.6 0.62 2.4 2.7 0.015 1.6 0.32

Blaokstrap llol. 8.3 2.5 21.0 21.4 0.038 6.5 1.2

Cane Syrup 1.3

o.60

1.2

s.o

0.010 1.0 0.11