Extracellular Microbial Polysaccharides

18 Applications of Xanthan G u m in Foods and Related Products

Downloaded by UNIV LAVAL on June 8, 2017 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0045.ch018

THOMAS R. ANDREW Kelco, Division of Merck & Co., Inc., 8225 Aero Drive, San Diego, CA 92123

Xanthan gum was approved for use as a food additive on March 19, 1969, by the Food and Drug Administration in accordance with 21 CFR 121.1224. Since then it has been used in a wide variety of foods for a number of important reasons including emulsion stabilization, temperature s t a b i l i t y , com p a t i b i l i t y with food ingredients, and its unique pseudoplastic rheological properties. It has been proposed that xanthan gum, which is produced by the microorganism Xanthomonas campestris, is in fact a survival device for the organism generating it and it has, through millions of years of evolution, been perfected for this purpose (1). Thus, i t is not surprising that a substance generated for the protection of a microorganism should possess such unusual properties and be so resistant to thermal, chemical, and biological degradation. A great deal of progress has been made toward understanding the chemistry of xanthan gum. Figure 1 shows the structure of xanthan gum as i n i t i a l l y postulated. It was shown that i t consisted of a sixteen-residue repeating unit composed of D-glucose, D-mannose, and D-glucuronic acid as shown (2, 3). In a paper published in 1975 Jansson and co-workers proposed the somewhat more simplified structure shown in Figure 2. This structure is composed of a back bone of 1 - 4 linked β-D-glucose units with side chains which consist of two mannose and (4) a glucuronic acid unit on every other glucose unit. Every other side chain carries a pyruvic acid group. In 1972 Rees proposed a double helix solution conformation (Figure 3) for xanthan gum which went a long way toward explaining the yield point phenomenon and the flat temperature-viscosity curve, unique among polysaccharides (5,6). A further extension of Rees's study (Figure 4) provided an 231

Sandford and Laskin; Extracellular Microbial Polysaccharides ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

EXTRACELLULAR MICROBIAL POLYSACCHARIDES


232



18.

ANDREW

Xanthan

Gum

in Foods and

Related

Products

233

e x c e l l e n t e x p l a n a t i o n o f why xanthan gum r e a c t s t o form e l a s t i c g e l s w i t h l o c u s t bean gum but not guar gum. The u n i f o r m l y d i s t r i b u t e d g a l a c t o s e s i d e c h a i n s a l o n g t h e mannose backbone o f guar gum p r e v e n t the c l o s e a s s o c i a t i o n o f the m o l e c u l e w i t h the xanthan gum h e l i x w h i l e the e x i s t e n c e o f "smooth" zones ( F i g u r e 5) i n the l o c u s t bean gum m o l e c u l e a l l o w s a s s o c i a t i o n and, t h e r e f o r e , g e l a t i o n ( 7 ) . As i s u s u a l l y t h e case w i t h the use o f gums, t h e o r y and p r a c t i c e have run on almost p a r a l l e l paths b u t the t w a i n have n o t y e t met. Theory h e l p s us u n d e r s t a n d t h e r e s u l t s b u t has not l e d us t o them. When xanthan gum e n t e r e d the food m a r k e t p l a c e i n 1969, i t s b a s i c p h y s i c a l p r o p e r t i e s were a c t i v e l y promoted, f o l l o w e d by a number o f suggested f o r m u l a t i o n s , a l l o f which were examples o f advances o v e r p r e v i o u s systems s t a b i l i z e d w i t h o t h e r gums. S a l a d d r e s s i n g w i t h e m u l s i o n s t a b i l i t y extended t o a y e a r o r more and s a l a d d r e s s i n g s t h a t c o u l d be r e t o r t e d o r r e p e a t e d l y f r o z e n were d e v e l o p e d . An i n s t a n t pudding which was almost the same as the cooked starch v e r s i o n was f o r m u l a t e d , and i n d u s t r y d e v e l o p e d a number o f o t h e r improved p r o d u c t s . P a s t e u r i z e d P r o c e s s e d Cheese

Spread

More r e c e n t work has been completed which demonstrates the u t i l i t y o f xanthan gum i n p a s t e u r i z e d p r o c e s s cheese s p r e a d ( 8 ) . U s i n g a s t a n d a r d f o r m u l a f o r p a s t e u r i z e d p r o c e s s cheese, samples were p r e p a r e d under d u p l i c a t e c o n d i t i o n s i n a cooker commonly used f o r t h i s purpose. As T a b l e I i n d i c a t e s , a number o f combinations o f xanthan gum, l o c u s t bean gum, and guar gum were e v a l u a t e d t o determine t h e optimum r a t i o f o r good meltdown, f i r m n e s s , s l i c e a b i l i t y , and f l a v o r r e l e a s e . I t i s i n t e r e s t i n g t o note t h a t o n l y one c o m b i n a t i o n g i v e s good r e s u l t s i n e v e r y c a t e g o r y , T r i a l No. 17A. These r e s u l t s n o t o n l y demonstrate the u t i l i t y o f xanthan gum b u t a l s o the n e c e s s i t y f o r u s i n g b l e n d s a t times t o o b t a i n f u n c t i o n a l advantages n o t o b t a i n a b l e w i t h s i n g l e t h i c k e n e r s . Each gum cont r i b u t e s a d e s i r a b l e c h a r a c t e r i s t i c t o the f i n a l p r o d u c t , b u t t h e s y n e r g i s t i c b l e n d i s b e t t e r than t h e sum o f i t s p a r t s . C o t t a g e Cheese D r e s s i n g Table I I again i l l u s t r a t e s the f u n c t i o n a l s u p e r i o r i t y o f the s y n e r g i s t i c b l e n d . C o t t a g e cheese




DOUBLE HELIX RANDOM COIL Predominant in the sol; Provide cross-linking can exist as "connectingjunctions in the gel. lengths" in gel structure and impart elasticity when they do so. Sol ;j=i Incipient g e l ^ Clear elastic gel ^

Figure 3.

Stiff gel ^

Turbid rigid gel

AGGREGATE Add cross-linking to consolidate the gel structure, thus acting as "super-junctions'." Phase separation syneresed gel

States of polysaccharide molecules and their role in gel prop erties

Figure 4. Schematic of galactomannan conformation. Each line represents a sugar unit consisting of the backbone composed of β-Ό-mannopyranose units and the side chains composed of a-O-gahctopyranose units.

Figure 5. Possible model for the inter action between xan than gum and locust bean galactomannan, resulting in gel for mation



18.

ANDREW

Xanthan Gum in Foods and Related Products

235

cream d r e s s i n g , which i s n o r m a l l y about 10 p e r c e n t b u t t e r f a t w i t h s a l t added, i s f o r m u l a t e d t o p o s s e s s enough v i s c o s i t y t o make i t c r e a m i e r and t o g i v e good c l i n g t o t h e c u r d . I f the v i s c o s i t y o f the cream i s t o o h i g h , t h e r e s u l t i n g c o t t a g e cheese w i l l be t o o " d r y " and t h e e a t i n g q u a l i t i e s w i l l s u f f e r . A n o t h e r p o t e n t i a l problem a r i s e s because o f t h e i n h e r e n t gummy m o u t h f e e l e x h i b i t e d by many gums a t a c o n c e n t r a t i o n o f 0.2 t o 0.3 p e r c e n t , t h e normal use l e v e l o f gums i n c o t t a g e cheese cream. As T a b l e I I i l l u s t r a t e s , a b l e n d o f xanthan gum, l o c u s t bean gum, and guar gum c a n be used t o d e v e l o p t h e v i s c o s i t y n e c e s s a r y f o r good c l i n g , b u t t h e a c t i v e gum conc e n t r a t i o n i s low enough so t h a t m o u t h f e e l and t e x t u r e do n o t s u f f e r ( 9 ) . The cream remains homogeneous and u n i f o r m l y mixed w i t h c u r d and does not separate w i t h time. L i q u i d C a t t l e Feed

Supplements

L i q u i d f e e d supplements, a l t h o u g h n o t f o o d i n t h e sense t h a t t h e y a r e consumed d i r e c t l y by humans, a r e n o n e t h e l e s s an i m p o r t a n t f a c t o r i n t h e f o o d supply. L i q u i d f e e d supplements a r e b a s i c a l l y one o r more n u t r i e n t m a t e r i a l s s u p p l i e d i n a l i q u i d v e h i c l e such as water o r m o l a s s e s . The g r e a t m a j o r i t y a r e added t o t h e d r y f e e d o f f e e d l o t c a t t l e and a r e s h i p p e d and s t o r e d i n l a r g e t a n k s where, because o f the formation o f p r e c i p i t a t e s o r f l o c c u l a n t s o r t h e addition o f insoluble material, maintaining uniformity is difficult. I t i s e s p e c i a l l y important t o maintain u n i f o r m i t y because v i t a m i n s and t r a c e m i n e r a l s which a r e added t o t h e r a t i o n t e n d t o adsorb on t h e s o l i d f l o c c u l a n t s t h a t form and w i l l n o t s t a y u n i f o r m l y d i s t r i b u t e d u n l e s s s e d i m e n t a t i o n i s p r e v e n t e d by t h e use o f a s u s p e n d i n g agent o r c o n t i n u o u s a g i t a t i o n . F i g u r e 6 i s a t y p i c a l l i q u i d f e e d supplement formul a t i o n o f the high-molasses, phosphoric-acid type. Note t h e s i m i l a r i t y t o f e r t i l i z e r . Figure 7 i l l u s t r a t e s t h e f u n c t i o n a l i t y o f xanthan gum as a s u s p e n d i n g agent a t room t e m p e r a t u r e , and F i g u r e 8 i l l u s t r a t e s i t s s t a b i l i t y a t 95°F (10). These f i g u r e s i l l u s t r a t e two p o i n t s : (1) xanthan gum i s an e x c e l l e n t s u s p e n d i n g agent because i t p o s s e s s e s a y i e l d p o i n t , and (2) s u s p e n d i n g q u a l i t i e s o f xanthan gum a r e n o t s i g n i f i c a n t l y d i m i n i s h e d by e l e v a t e d t e m p e r a t u r e s as o c c u r s w i t h l i q u i d f e e d supplements i n warm weather. I n a d d i t i o n , because o f i t s p s e u d o p l a s t i c i t y , xanthan gum f a c i l i t a t e s pumping.


EXTRACELLULAR MICROBIAL

236

Table

I

POLYSACCHARIDES

F O R M U L A S AND RESULTS

OF EXPERIMENTAL PASTEURIZED PROCESSED CHEESE SPREADS % GUM CONTENT TRIAL NUMBER

XANTHAN GUM

GUAR GUM

LBG

BODY RESILIENCY

SLICING PROPERTIES

MOUTH FEEL

FLAVOR RELEASE

SANDWICH MELT

1A

0.2

Fair

Tacky

Lumpy

Fair

Excellent

2A

0.5

Fair

Tacky

Lumpy

Fair

Good

3A

0.8

Fair

Tacky

Lumpy

Fair

Good

4A

— —

Good

Good

Lumpy

Fair

Good

Excellent

Excellent

Lumpy

Fair

Excellent

Excellent

Excellent

Lumpy

Fair

Excellent

5A 6A


ORGANOLEPTIC EVALUATIONS

0.2 0.5 0.8

— —

—

7A

0.2

Poor

Tacky

Smooth

Excellent

Good

8A

0.5

Poor

Tacky

Smooth

Excellent

Excellent

9A

0.8

Fair

Tacky

Smooth

Excellent

Excellent

— — — — —

0.14

Fair

Tacky

Lumpy

Fair

Good

0.45

Fair

Tacky

Lumpy

Fair

Good

0.35

Good

Tacky

Smooth

Good

Excellent

0.25

Fair

Tacky

Lumpy

Fair

Good

10A

0.06

11A

0.05

12A

0.15

13A

0.25

14A

0.24

0.56

Good

Tacky

Smooth

Good

Excellent

15A

0.06

0.04

0.10

Good

Tacky

Smooth

Good

Good

16A

0.15

0.10

0.25

Good

Good

Smooth

Good

Excellent

17A

0.24

0.16

0.40

Excellent

Excellent

Smooth

Excellent

Excellent

18A*

0.15

0.10

0.25

Good

Good

Smooth

Good

Good

'Trial 1SA contained 0.2 percent pimento solids or 12.50 pounds of drained pimentos per batch.

T^.Ul^

'Cible

Τ Τ

11

Dressing Viscosities (cps) (| itial/24hr.) n

Percent Stabilizer:

0.05

0.10

0.15

Xanthan gum/ galactomannan blend Xanthan gum Guar gum Blend 1 Blend 2 Blend 3 Blend 4 Locust bean gum

27/41 10/10 6/4 7/8 6/5 4/12 7/13 11/16

118/115 40/60 15/31 9/21 8/11 7/19 10/24 23/35

260/245 107/133 33/60 16/42 13/19 18/41 21/49 52/69

0.20

0.30

Not evaluated 373/480 160/250 45/71 27/58 62/105 66/135 175/95

155/225 51/86 23/47 18/35 36/67 51/95 105/130

Cane Molasses, 79.5 Brix

67.5

Urea Liquor, 50%

20.9

Salt

5.0

Trace Minerals

0.2

Phosphoric Acid, 75%

6.4 100.0

%

Figure 6. Liquid supplement for mulation high molasses, range type

Protein Equivalent

32

Phosphorus

1.5

Solids, Calculated

60


ANDREW

Xanthan Gum in Foods and Related Products


18.


237

238

EXTRACELLULAR

Calf Milk

MICROBIAL

POLYSACCHARIDES

Replacers


A r e l a t e d a p p l i c a t i o n i s t h e use o f xanthan gum f o r s t a b i l i z i n g c a l f m i l k r e p l a c e r s . C a l f milk r e p l a c e r s may c o n s i s t o f d r i e d whey and h e a t p r o c e s s e d soy beans o r s i n g l e - c e l l p r o t e i n . A dry mix i s added t o water, s t i r r e d t o d i s p e r s e t h e s o l i d s , and f e d t o c a l v e s . I f t h e f e e d i s n o t s t a b i l i z e d , t h e i n s o l u b l e s o l i d s w i l l q u i c k l y s i n k and t h e s h o r t term u n i f o r m i t y which i s r e q u i r e d w i l l be l o s t . As l i t t l e as 0.032 p e r c e n t xanthan gum can p r o v i d e enough s t a b i l i t y t o m a i n t a i n u n i f o r m i t y , as F i g u r e s 9, 10, and 11 show ( 1 1 ) . Thermal P r o c e s s i n g Recent work by Cheng and Kovacs has e x p l o r e d t h e r h e o l o g i c a l p r o p e r t i e s o f xanthan gum under h i g h temperature and moderate shear found i n most a g i t a t e d commercial c a n n i n g systems (12). A Fann 50C v i s cometer, an i n s t r u m e n t which p e r m i t s t h e measurement o f v i s c o s i t y a t shear r a t e s from 1.7 - 1075 sec"" , temperatures t o 500°F, and p r e s s u r e s t o 1000 p s i , was used. F i g u r e 12 d e p i c t s t h e v i s c o s i t y drop t h a t xanthan gum undergoes a t two a r b i t r a r i l y s e l e c t e d shear r a t e s , 170 sec"" and 511 s e c " , w i t h and w i t h o u t NaCl. The well-known " f l a t " v i s c o s i t y v e r s u s temperature c u r v e i s seen from ambient temperature t o about 190°F w i t h a l l s o l u t i o n s . The s t a b i l i t y t o t h e r m a l d e g r a d a t i o n imparted by an e l e c t r o l y t e can a l s o be seen. Furthermore, F i g u r e 9 i l l u s t r a t e s that the e l e c t r o l y t e - s t a b i l i z e d solut i o n s l o s e 98 p e r c e n t o f t h e i r v i s c o s i t y a t r e t o r t temperature (250°F) and r e c o v e r about 80 p e r c e n t o f t h e i r o r i g i n a l v i s c o s i t y on c o o l i n g . Obviously, a t h i c k e n e r t h a t i s t h i n a t r e t o r t temperature w i l l f a c i l i t a t e heat t r a n s f e r , thereby shortening the p r o c e s s time. T h i s r e d u c t i o n i n p r o c e s s time i s i m p o r t a n t f o r i n c r e a s i n g p r o d u c t i v i t y and i n t h e t h e r m a l p r o c e s s i n g o f foods which a r e a d v e r s e l y a f f e c t e d by " o v e r c o o k i n g " . 1

1

Other

1

Advances

Xanthan gum has a l s o been used t o s t a b i l i z e f r o z e n d e s s e r t s and t o s t a b i l i z e t o o t h p a s t e , where i t s r h e o l o g i c a l p r o p e r t i e s can be used t o f o r m u l a t e a p r o d u c t t h a t t h i n s when squeezed from t h e tube but has t h e o r i g i n a l c o n s i s t e n c y on t h e b r u s h . A s y n e r g i s m w i t h d e x t r i n has a l s o been used i n d e n t u r e



ANDREW

Xanthan

Gum in Foods and Related

Products

Figure 9

Figure 10


240



Figure 11

Figure 12. The effect of retorting at shear rates of 170 sec' and 511 sec' on the viscosities xanthan gum with and without electrolyte 1

1



18.

ANDREW

Xanthan

Gum

in Foods

and Related

Products

241

a d h e s i v e s and i n a number o f f o o d s . Xanthan gum a l o n e and i n c o m b i n a t i o n w i t h galactomannans shows e x c e l l e n t promise i n canned, g r a v y - t y p e p e t f o o d s . I t has a l s o been r e p o r t e d t h a t xanthan gum shows good p o t e n t i a l as a g l u t e n s u b s t i t u t e i n b r e a d (13, 1 4 ) . A l t h o u g h t h i s p o t e n t i a l use i s i m p o r t a n t t o t h e segment o f t h e p o p u l a t i o n who a r e a l l e r g i c t o g l u t e n , i t has much b r o a d e r i m p l i c a t i o n s as a p o s s i b l e a d j u n c t t o l o w - q u a l i t y wheat f l o u r o r grains that are not s u i t a b l e f o r baking. We have reviewed today some o f t h e more r e c e n t developments i n xanthan gum usage. I n view o f t h e unique p r o p e r t i e s i t p o s s e s s e s as a r e s u l t o f i t s f u n c t i o n i n n a t u r e , we can undoubtedly e x p e c t even w i d e r usage i n t h e f u t u r e .

Literature Cited 1. "Xanthan Gum/KELTROL/KELZAN, A Natural Polysac charide for Scientific Water Control," Kelco Co., Second Edition. 2. Sloneker, J . Η., James Α . , Am. J. Chem. (1962) 40, 2066-71. 3. Siddiqni, Carbohyd. Res. (1967)4 (4), 284-91. 4. Jansson, P. Ε . , Keen, L., and Lindberg, Β . , Carbohyd. Res. (1976) 45 (1), 275-82. 5. Rees, D. Α . , Biophysical Society Winter Meeting, London, England (1973). 6. Rees, D. Α . , Biochem. J . (1972) 126, 257-73. 7. Dea, I. C. Μ., McKinnon, A. A. and Reese, D. A. (1972) J . Mol. B i o l . 68 (1), 153-72. 8. Kovacs, P . , and Igoe, R. S. (1976) Food Product Development, in press. 9. Kovacs, P. and Titlow, B. D. (1976) American Dairy Review 38 (4) 34J-34N. 10. Jackman, K. R., Randel, J . H. and Wintersdorff, P. (1976) A Unique Suspending Agent, National Feed Ingredients Association Meeting, Kansas City, Missouri (April 15). 11. Ibid. 12. Kovacs, P. and Cheng, H. (1976) Effects of High Temperatures and Shear Rates on Hydrocolloid Viscosities During Simulated Canning and HTST Processing Conditions. Unpublished report. 13. Kulp, K . , Hepburn, F. Ν . , and Lehmann, T. A. (1974) The Baker's Digest 48 (3), 34-37. 14. Christianson, D. D. Gardner, H. W., Warner, Κ., Boundy, Β. K. and Inglett, G. E. (1974) Food Technology 28 (6), 23-29.


Extracellular Microbial Polysaccharides

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