Synthetic Membranes: Volume II - American Chemical Society

3 Industrial Application of Ultrafiltration and Hyperfiltration in the Food and Dairy Industries Downloaded by UNIV OF CALIFORNIA SAN DIEGO on June 2, 2015 | http://pubs.acs.org Publication Date: May 27, 1981 | doi: 10.1021/bk-1981-0154.ch003

OLE

JENTOFT OLSEN

D D S - N A K S K O V , Division of the

Danish Sugar Corporation, 4900 Nakskov, Denmark

The development s t a r t e d by Loeb and S o u r i r a j a n i n 1960, has r e s u l t e d in something q u i t e d i f f e r e n t than d e s a l i n a t i o n of sea and b r a c k i s h water. I am q u i t e c e r t a i n that in those days they d i d not t h i n k of Feta cheese and low-alcohol beer. I have s e l e c t e d these products in order to show that membrane filtration is an accepted process in the food i n d u s t r y and not j u s t a pipe dream of the f u t u r e , on which we all based our hopes during the first years of the process. Feta Cheese Feta cheese o r i g i n a t e s from Greece, where it was originally produced from yew s m i l k . Today it is an important i n g r e d i e n t of the d a i l y d i e t in Southeast Europe and the A r a b i c c o u n t r i e s . I n these countries the m i l k production i s too low to s u s t a i n a l e v e l of s e l f - s u f f i c i e n c y w i t h t h i s type of cheese. Consequently s e v e r a l North European c o u n t r i e s , among them Denmark, have s t a r t e d a comprehensive production of Feta cheese f o r export purposes. The p r i n c i p l e of any cheese production i s that the m i l k p r o t e i n s are brought to an i n s o l u b l e form by means of enzymes, the soc a l l e d coagulation. Then the coagulated p r o t e i n i s s i f t e d from the components of the remaining m i l k . These components being water, s a l t s , l a c t o s e , and the whey p r o t e i n s lactalbumin and l a c t o g l o b u l i n . The whey p r o t e i n s c o n s t i t u t e up to 20% of the t o t a l p r o t e i n content i n m i l k . So these p r o t e i n s are wasted during the process. The p r i n c i p l e of cheese production by u l t r a f i l t r a t i o n i s that the p r o t e i n s are concentrated by UF i n the s o l u b l e form, i . e . bef o r e the enzyme treatment. The concentration i s c o n t r o l l e d i n such a way that the composition of the concentrate as regards f a t , prot e i n , s a l t s and water, i s equivalent to the composition of the f i n ished cheese. I t i s at t h i s point the enzyme i s added, causing the cheese to set i n the form, i n t o which i t has been poured. The whey p r o t e i n s , which were p r e v i o u s l y wasted during the t r a d i t i o n a l process, remain i n the f i n i s h e d cheese, r e s u l t i n g i n increased prod u c t i o n and t h e r e f o r e higher p r o f i t s . I s h a l l r e v e r t to t h i s l a t e r . '

0097-6156/81/0154-0027$05.00/0 © 1981 American Chemical Society In Synthetic Membranes: Volume II; Turbak, A.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

28

SYNTHETIC MEMBRANES:

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on June 2, 2015 | http://pubs.acs.org Publication Date: May 27, 1981 | doi: 10.1021/bk-1981-0154.ch003

Standardized

Ultrafiltration

Concentrate

H F A N D U F USES

Pasteurization

Pasteurized

39.5 % T S

Homogenisation

Milk

16.4 % Protein 17.8 % Fat

C u r d l i n g «- Rennet

12.5 % T S 3.4 % Protein 3.5 % fat

Permeate

S o u r i n g -• 2-3 % whey

5.5 % T S

Salting Final C h e e s e

+ salt

43.0 % T S 22.0 % Proteins 17.5 % Fat 3 % Salt

Figure 1.

The UF process for feta cheese

Milk tons/day Traditional method

300

Ultrafiltration method

300

Extra Yield

Fat tons/day

1.8

Cheese Sales price $/day tons/day 41

73,800

57

102,600

16

28,800

Fat addition Operation Costs

-=-6,700 -f 3,900

Profit by the UF process

18,200

Figure 2.

Economy in feta cheese production by UF

In Synthetic Membranes: Volume II; Turbak, A.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.


3.

OLSEN

29

Food and Dairy Industries

Figure 3.

0rum Plant

. . . . . . Precipitation

~ . Unsoluble Drying—..... Milkprotem

in. »• Ultrafiltration

% r • Soluble Drying— .... Milkprotem Drying—Whey-Protein

-Ultrafiltration +

Diaf iltration

Sweet WheyUltraf iltration Permeate

Concentrate—Drying—Whey-Protein -Crystallization—Drying—Lactose

Acid Whey

Ultrafiltration

Acid

W

h

Drying— Protein

e

y

Figure 4. UF of whey




Figure 5.

Figure 6.

H F AND U F

Denmark proteins (outside)

Denmark proteins (inside)


USES


3.

OLSEN


31

Figure 1 shows, how u l t r a f i l t r a t i o n i s incorporated i n the process. Today a l l Danish d a i r i e s producing Feta cheese, w i t h one exc e p t i o n , base t h e i r production on u l t r a f i l t r a t i o n . The l a r g e s t of these i n s t a l l a t i o n s , b u i l t i n 1977, i s today t r e a t i n g 300,000 m e t r i c tons m i l k d a i l y . Investment i n UF p l a n t s amounts t o approx. 1 m i l l . $. The economical s i d e of the matter i s as f o l l o w s (see Figure 2 ) . Indeed, a notable increase i n p r o f i t s as a r e s u l t of the work c a r r i e d out at UCLA i n 1960 and followed-up by DDS i n 1965. Figure 3 shows the DDS UF-plant at the above mentioned Feta cheese f a c t o r y . I t comprises a t o t a l of 20 DDS UF modules, type 35, each w i t h 27 m^ (approx. 297 f t ^ ) membrane area. The membrane a p p l i e d i s o f s y n t h e t i c m a t e r i a l w i t h a nominal c u t - o f f value o f 2Q,000. The p l a n t can operate round the c l o c k , and the c l e a n i n g time i s approx. 2 hours every 24 hours. The c l e a n i n g i s c a r r i e d out w i t h a s o l u t i o n of hot 0.5% sodium hydroxide, f o l l o w e d by a s o l u t i o n of hot 0.3% n i t r i c a c i d , and s t e r i l i z a t i o n i f necessary w i t h C l ^ . The membrane l i f e time i s approx. 1 year. Proteins The i n t r o d u c t i o n of membrane f i l t r a t i o n i n connection w i t h d a i r y production has r e s u l t e d i n a wide range of new p r o t e i n enr i c h e d products of which the whey p r o t e i n s have a t t r a c t e d the l a r g e s t amount of a t t e n t i o n . F i g u r e 4 shows a few of the d i f f e r e n t products which are produced today. The l a r g e s t d a i r y company i n Denmark, c a l l e d "Dairy Denmark" i s , as f a r as I know, the most p r o g r e s s i v e one i n the world today w i t h regards t o the production of whey p r o t e i n s by means of u l t r a f i l t r a t i o n . Figure 5 i s a photo of a q u i t e new p r o t e i n f a c t o r y , c a l l e d "Denmark P r o t e i n s " , whose s o l e purpose i s t o u l t r a f i l t r a t e 1,000 m e t r i c tons of whey per day f o r the p r o d u c t i o n of approx. 10 m e t r i c tons pure whey p r o t e i n i n powder form, and as a by-product approx. 50 m e t r i c tons of l a c t o s e . The p l a n t was put i n t o o p e r a t i o n i n May, 1980. Up t i l l now nothing has been r e l e a s e d concerning the t o t a l economy of the p l a n t , but I am convinced that "Dairy Denmark" have made sure that the economy i s sound. The essence of t h i s p l a n t i s of course the UF p l a n t i t s e l f , which i s shown i n Figure 6. I t i s a DDS plant of the same type as at the Fe£a cheese d a i r y , c o n s i s t i n g of 45 modules, type 35, each w i t h 42 m (452 f t ^ ) membrane area. The p l a n t i s f u l l y automatic, c o n t r o l l e d by micro processors and i n t e g r a t e d i n a s u p e r i o r t o t a l c o n t r o l of the whole f a c t o r y . The p r i n c i p l e of the p l a n t c o n s t r u c t i o n i s shown i n F i g u r e 7. I f a higher p u r i t y i s d e s i r e d than achieved by normal u l t r a f i l t r a t i o n , water may be added during the process ( d i a f i l t r a t i o n ) . I n t h i s way more i m p u r i t i e s w i l l pass through the membranes.


32


f-Preconcentration—j

H F AND U F

USES

-

Diafiltration—j— com!. 1

Feed _tank


module Booster pump

Feedpump seo^p

£ nil f If Water

Figure 7.

Figure 8.

Continuous UF Plant (principle)

Brrup, HF of whey in Denmark


Product tank

3.

OLSEN

33



tons vapour kg fuel kWh per ton water removed Evaporation of whey 5 % TS - 20 % TS

0.18

13.8

53.2

Hyperfiltration of whey 5 % TS — 20 % TS

6.8

Saving in %

88

Figure 9.

Figure 10.

HF of whey

HF plant for removal of alcohol



34


H F AND U F

Figure 11.

Development center in the dairy industry (outside)

Figure 12.

Development center in the dairy industry (inside)


USES


OLSEN


Figure 13.

DDS-NAKSKOV


36


H F A N D U F USES

The product composition, i . e . the p r o p o r t i o n between p r o t e i n and l a c t o s e i n the f i n a l product, may be c o n t r o l l e d from the cent r a l c o n t r o l room. Thus the f a c t o r y i s able to produce p r o t e i n powder w i t h compositions v a r y i n g from approx. 35% p r o t e i n of t o t a l s o l i d s to approx. 85% p r o t e i n of t o t a l s o l i d s . The f i r s t ment i o n e d i s a product w i t h a composition l i k e cheap skim-milk powder, whereas the l a t t e r i s an expensive product used f o r babyfood and d i e t e t i c food.


Concentration of Whey Today d i r e c t c o n c e n t r a t i o n of whey i s known and accepted as an exceedingly a t t r a c t i v e supplement o r a l t e r n a t i v e to evaporation. F i g u r e 8 shows a t y p i c a l DDS RO plant c o n s i s t i n g of 14 19 m (205 f t ) modules equipped w i t h membranes of c e l l u l o s e a c e t a t e , not v e r y d i f f e r e n t from those developed i n 1960. Around 6 m e t r i c tons are t r e a t e d d a i l y . F i g . 9 shows a comparison of the energy consumption by evap o r a t i o n and h y p e r f i l t r a t i o n (also c a l l e d reverse osmosis). 2

2

Removal o f the A l c o h o l i n Beer A new f i e l d i s the removal of a l c o h o l i n beer by means of h y p e r f i l t r a t i o n . "De forenede B r y g g e r i e r " - perhaps b e t t e r known under the names Tuborg and C a r l s b e r g - have developed a process f o r removal of the a l c o h o l i n beer by means of the DDS h y p e r f i l t r a t i o n system. The advantages w i t h t h i s are that the a l c o h o l percentage may be adjusted according to the d i f f e r e n t marketing areas - without having to change the brewing process. Figure 10 shows a DDS p l a n t f o r the h y p e r f i l t r a t i o n of Beer. DDS Development I n order to emphasize how much we expect of the f u t u r e DDS has b u i l t a new d a i r y f o r development purposes. The main o b j e c t s being product and process development based on membrane f i l t r a t i o n i n the food i n d u s t r y . The d a i r y i s shown i n Figures 11 and 12. DDS-Nakskov F i g u r e 13 shows the DDS p r o d u c t i o n plant i n Denmark f o r membrane f i l t r a t i o n equipment. Around 250 people are working i n t h i s ever expanding company. RECEIVED

December 4, 1980.


Synthetic Membranes: Volume II - American Chemical Society

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