Synthetic Membranes - American Chemical Society

2 Membrane Processes in Must and Wine Treatment 1

E. DRIOLI, G. ORLANDO, S. D'AMBRA , and A. A M A T I

2

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.ch002

Istituto di Principi di Ingegneria Chimica, University of Naples, Italy

ive.

Membrane processes are one o f the most important s e p a r a t i o n technologies in food i n d u s t r y . The operate, a t room temperature, r e q u i r e no a d d i t i o n of chemicals and are gentle and non-destruct Their potentiality is confirmed by an annual growth r a t e of 37% (1). However the major area f o r ultrafiltration and reverse osmosis in food a p p l i c a t i o n s is mainly whey purification, and the d a i r y i n d u s t r y in g e n e r a l . This market has been estimated of 2 million US d o l l a r s in 1976 and 5 million US d o l l a r s in 1981. Pressure d r i v e n membrane processes will p l a y an important r o l e in other areas typical o f the food i n d u s t r y and in the treatment o f must and wine. Great progress has been made d u r i n g the last few years in: a) the development of new membranes w i t h h i g h r e s i s t a n c e t o s o l v e n t s , pH, temperature, Cl2 e t c . b) the development of membrane p l a n t e n g i n e e r i n g ; c) in the b e t t e r understanding of f o u l i n g and membrane deterior ation.

1

Current address: D'Ambra Vini d'Ischia, Ischia, Italy.

2 Current address: Istituto di tecniche agrarie, University of Bologna, Italy. 0097-6156/81/0154-0017$05.00/0 © 1981 American Chemical Society In Synthetic Membranes: Volume II; Turbak, A.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

18

SYNTHETIC MEMBRANES:

HF

AND

UF

USES


Wine technology now r e q u i r e s v a r i o u s s e p a r a t i o n techniques which could p r o f i t a b l y be replaced by membrane processes ( 2 ) . C e r t a i n enzymes present i n grapes are r e s p o n s i b l e f o r wine problems such as c l o u d i n g , darkening or an o x i d i z e d t a s t e . To prevent t h i s , w i n e r i e s r o u t i n e l y t r e a t must and wines w i t h s u l f u r d i o x i d e . In a d d i t i o n to i t s a n t i m i c r o b i a l a c t i v i t y , SO2 has an a n t i o x i d a t i v e p r o p e r t y which prevents browning and t a s t e d e f e c t s . Polyphenoloxidase has d e t r i m e n t a l e f f e c t s on wine q u a l i t y . However enzymes are a l s o responsable f o r the formation of c e r t a i n d e s r r able e s t e r s which are e s s e n t i a l to the aroma or bouquet of the wine. Methods which reduce the u n d e s i r a b l e e f f e c t s of polyphenoloxid_ ases i n c l u d e p r e s s i n g , c e n t r i f u g i n g or s e t t l i n g musts, b e n t o n i t e f i n i n g and thermal treatment (70°C f o r 3 min). Depending of the type of grapes, the length of fermentation and the type of wine produced, the f r e s h wine a f t e r r a c k i n g and rough f i l t r a t i o n may s t i l l be cloudy because of suspended c o l l o i d a l p a r t i c l e s of grape or yeast components. This cloudiness may remain f o r a long time. I t i s unusual when a good wine becomes b r i l l i a n _ t l y c l e a r by n a t u r a l s e t t l i n g . With present technology, such cloud^i ness caused by grape of yeast p r o t e i n s , p e p t i d e s , p e c t i n s , gums, dextrans unstable grape pigments, tannins e t c . may be removed from wine by the j u d i c i o u s use of small amounts of f i n i n g agents. These adsorb or c h e m i c a l l y and p h y s i c a l l y combine w i t h the c o l l o i d a l p a r t i c l e s or n e u t r a l i z e t h e i r e l e c t r i c charges causing them to agglomerate and g r a v i t a t e to the bottom. Such treatment combined w i t h subsequent f i l t r a t i o n c l a r i f i e s the wine. B e n t o n i t e , one of the most popular f i n i n g agents i n winemaking, e f f e c t i v e l y removes p r o t e i n m a t e r i a l s . A c t i v a t e d carbon, g e l a t i n , c a s e i n and p o l y ( v i n y l p i r r o l i d o n e ) may a l s o be used and a i d i n the removal of u n s t a b l e tannins and other pigments. U.S. r e g u l a t i o n s however l i m i t the use of f i n i n g agents. The c l a r i f y i n g agents must not remain i n the wine. A f t e r fermentation, wine becomes supersaturated w i t h potassium b i t a r t r a t e . The removal of t h i s excess i s necessary to avoid sedimentation a f t e r the wine i s b o t t l e d . A c o l d s t a b i l i z a t i o n technique where the wine i s c h i l l e d j u s t above i t s f r e e z i n g p o i n t i s g e n e r a l l y used. P r o t e c t i v e c o l l o i d s , which prevent the c r y s t a l _ l i z a t i o n of the excess potassium b i t a r t r a t e make a wine r e s i s t e n t to c o l d s t a b i l i z a t i o n even during prolonged r e f r i g e r a t i o n . In those

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

2.

DRIOLI E T A L .

Must and Wine Treatment

19


cases i o n exchange treatment of the wine as been suggested t o render the e n t i r e l o t of wine potassium b i t a r t r a t e s t a b l e when blended back (2 ). E l e c t r o d i a l y s i s has a l s o been e x p l o r e d . The i n h i b i t i o n of m a l o - l a c t i c fermentation can be obtained by SO2 (^30 m g / l i t e r ) , maintainance of storage temperature at l e s s than 18°C and adjustment of pH to at l e a s t below 3.3. K i l l i n g or removing the b a c t e r i a from wine i s a more d e f i n i t e step t o s t a b i l i z e wine a g a i n s t m a l o - l a c t i c f e r m e n t a t i o n . P a s t e u r i z a t i o n and p a r t i c u l a r l y HTST treatment (high temperature, s h o r t time 98°C f o r one second - w i t h r a p i d c o o l i n g ) i s o f t e n used. S t e r i l e f i l t r a t i o n has a l s o been used w i t h 0.45ytun membrane f i l t e r s . In t h i s paper p r e l i m i n a r y experimental r e s u l t s obtained i n a U n i v e r s i t y - I n d u s t r y j o i n t research p r o j e c t are r e p o r t e d . The t e s t s have been c a r r i e d out i n cooperation w i t h a medium s i z e w e l l known winery. The aim was to analyze the p o t e n t i a l of u l t r a , f i l t r a t i o n and reverse osmosis i n s o l v i n g some of the problems or i n improving the e x i s t i n g technology i n wine making. A diagram of the p o t e n t i a l of pressure d r i v e n membranes i n must treatment i s presented i n f i g . l . In t h i s paper we w i l l d i s c u s s the experiments on must s t a b i l i z a t i o n a v o i d i n g SO2 a d d i t i o n , and on the c o n t r o l of polyphenols and c a t i o n s i n the must. Various polymeric membranes i n d i f f e r e n t c o n f i g u r a t i o n s have been t e s t e d . The m a j o r i t y of them have alreacfy been commercially used i n other food or biomedical a p p l i c a t i o n s . EXPERIMENTAL A l l the experiments d e s c r i b e d i n t h i s paper have been c a r r i e d out on white must. The m a j o r i t y of the u l t r a f i l t r a t i o n (UF) experiments have been performed u s i n g the l a b o r a t o r y u n i t shown i n f i g . 2 . The apparatus was constructed to use c a p i l l a r y membranes manufactured by the Berghof I n s t i t u t e (Tubingen, Germany). The p h y s i c a l p r o p e r t i e s of the membranes are given i n Table I . Table I I shows the r e j e c t i o n f o r p r o t e i n s , p o l y p h e n o l s and sugars measured u s i n g three d i f f e r e n t modulis. The must was f i l t e r e d through a BMR 500515 modulus ( c u t - o f f 50.000 mw). The permeate was then u l t r a f i l t e r e d through a BMR 10515 ( c u t - o f f 10.000 mw) and the permeate from t h i s step was u l t r a f i l t e r e d through a BMR 021.006 ( c u t - o f f 2.000 mw) modulus.


20


H F AND U F

USES


ULTRAFILTRATION

STABILIZED MUST; IDEAL SUB STRATE FOR SELECTED YEASTS

REVERSE OSMOSIS

NATURAL DYES

Figure 1.

Potentialities for UF and RO in must treatment

r s

M

X V Permeate

n Figure 2. Schematic of UF equipment: B, capillary membrane modulus; S, must reservoir; M, manometers.

M


2.

DRIOLI E T A L .


21

TABLE I C h a r a c t e r i s t i c s of the f i l t r a t i o n u n i t s .


cut-off (MW)

tubes diameter (mm)

membrane area (m ) 2

max pressure (bar)

filtration capacity (l/m h) 2

1

50.000

1.5

0.5

1.2

300

2

10.000

1.5

0.5

1.2

120

3

2.000

0.6

1.0

2.0

10

4

18.000

25.4

4.0

150

type : (1) BMR (2) BMR (3) BMR (4) HFM

500515 100515 021006 180

TABLE I I 1

2

MUST

3

c

P (g/lt)

R%

P (g/lt)

R%

P (g/lt)

R%

i (g/lt)

Total nitrogen

0.129

8

0.118

16

0.118

16

0.140

Total polyphen.

0.241

9

0.213

19

0.114

57

0.264

Sugar

162

0

162

C

C

0

C

162

0


162


22


HF

AND

UF

USES

Sugar r e j e c t i o n was always zero. Polyphenol r e j e c t i o n increased from 9% to 57% w i t h decreasing membrane c u t - o f f . D i f f e r e n c e i n polyphenol r e j e c t i o n have been observed when the must i s u l t r a f i l t e r e d i n the f i r s t UF step w i t h the BMR 100515 and a f t e r w i t h the BMR 021006, as reported i n t a b l e I I I . Fig.3 shows the t y p i c a l behaviour of the u l t r a f i l t r a t e f l u x observed i n these experiments. A constant f l u x was g e n e r a l l y obtained a f t e r two hours. Table IV shows the f i n a l must u l t r a f i l t r a t e f l u x v a l u e s . A l l the experiments were c a r r i e d out at the same a x i a l v e l o c i t y and at the same a p p l i e d pressure. Table V shows r e s u l t s obtained w i t h t u b u l a r membranes (Abcor-USA). P a r t i c u l a r a t t e n t i o n was devoted to the c o n t r o l of membrane fouling and membrane c l e a n i n g . A c i d - a l k a l i n e washing was t e s t e d and low c o n c e n t r a t i o n c h l o r i n e s o l u t i o n s were a l s o used. The recovery of i n i t i a l f l u x e s was g e n e r a l l y 50% w i t h the new modulus, and higher then 95% w i t h a used modulus. These r e s u l t s i n d i c a t e the e x i s t e n c e of a c e r t a i n i r r e v e r s i b l e f o u l i n g of the new membranes, which come to steady s t a t e v a l u e s , and does not increase w i t h membrane reuse. The must u l t r a f i l t e r e d w i t h h i g h f l u x membranes has a l s o been t r e a t e d w i t h membranes having intermediate or very h i g h r e j e c t i o n f o r e l e c t r o l y t e s . C e l l u l o s e acetate and polyamide membranes were used. The Reverse Osmosis apparatus shown i n f i g . 4 was used. The t e s t s were c a r r i e d out w i t h high a x i a l flow r a t e , s u f f i c i e n t to promote a t u r b u l e n t regime upstream from the semipermeable membrane, f o r m i n i m i z i n g c o n c e n t r a t i o n p o l a r i z a t i o n phenomena ( 4 ) . Table VI shows the r e j e c t i o n measured f o r t o t a l polyphenols and sugars w i t h DDS 800 and PA 300 membranes. Sugar r e j e c t i o n s increased from about 20% w i t h DDS 800 to 100% w i t h PA 300. Table V I I shows the r e j e c t i o n s of v a r i o u s c a t i o n s u s i n g the PA 300 membrane. The r e j e c t i o n f o r the m a j o r i t y of c a t i o n s i s higher than 97%. Only C u and Z n permeate e a s i l y through the membrane. The r e j e c t i o n s f o r these two c a t i o n s i s e s s e n t i a l l y zero. The reason i s a t t r i b u t e d to a h i g h s p e c i f i c i n t e r a c t i o n of Cu and Zn w i t h the polymeric m a t e r i a l s forming the membranes and to Donnan equilibrium. + +

+ +

F l u x decay i n the reverse osmosis t e s t has been determined and minimized u s i n g appropriate f l u i d dynamic regimes. T y p i c a l f l u x decay w i t h DDS 800 and PA 300 are shown i n F i g u r e 5 and 6. The feed was must u l t r a f i l t e r e d through BMR c a p i l l a r y membranes.


2.

DRIOLI E T A L .

23


TABLE I I I

c

BMR 100515 R% (g/lt)

BMR 021006 (g/lt) R%

c

MUST c.(g/lt)


P Total nitrogen

0.218

20

0.151

45

0.274

Total polyphenol

0.674

8

0.618

15

0.731

TABLE IV Must u l t r a f i l t r a t e

fluxes

P = 0.5 atm T = 20°C

flux 1/m h

MEMBRANE

2

1

30

2

18

3

2,5

TABLE V Membrane HFM 180 P = 2 atm T = 25°C J = 20,2 l/m h 2

c. I

Total

741 mg/1

c

R%

P 190 mg/1

74

nitrogen Sugars

18%

18%


0

24


H F A N D U F USES

TABLE VI


DD S 800

PA 300

FEED

c (g/l) p

R%

c (g/D

R%

Total Nitrogen

0.130

52

0.016

94

0.26

Total Polyphenol

0.243

45

0.012

98

0.51

Sugars

134

21

traces

100

166

p

c.(g/l)

TABLE V I I Membrane PA 300 P = 34 atm T = 10°C

c (mg/l)

c (mg/l)

R°(%)

N (total)

256

16

0.94

Polyphenols

576

12

0.98

Sugars

163 • 1 0

//

1.00

1255

18

0.98

77

4

0.95

123

4

0.97

i

2

p

3

+

K Na

+

Ca

+ +

Mg

+ +

74

1

0.97

Fe

+ + +

11.5

1.6

0.86

Cu

+ +

0.9

0.9

0

Zn

+ +

2.3

1.9

0.17

Mn

+ +

0.9

//

1.00


2.

DRIOLI E T A L .


25

BRM 50 05 15

T = 23 °C

Figure 3. UFfluxas a function of time: Feed, white must.

2 0 0


t , min

PC

Permeate

Figure 4. Scheme of RO laboratory apparatus: C, membrane cell; S, reservoir; P, volumetric pump.

V

BT"

80

E

40

200

400

600 t , h

Figure 5. Typical flux decay with CA DDS-800 membranes. Feed: white must previously ultraflltered through BMR100515 modulus; T = 10°C, P = 35 atm.

PA 300 P= 32 atm

t .h

20

Figure 6. Typical flux behavior with PA -300 polyamide composite membranes. Feed: white must previously ultraflltered through BMR-021006 modulus; T = 10°C.


26


HF

AND

UF

USES

I n t e r e s t i n g e f f e c t s have been observed on the u l t r a f i l t e r e d must f o r what concerns c o l o r changes and wine s t a b i l i t y . The a n a l y s i s of these e f f e c t s are s t i l l i n progress i n cooperation w i t h s p e c i a l i s t i n winemaking.


DISCUSSION AND

CONCLUSION.

The r e s u l t s described i n t h i s r e p o r t show some of the uses that pressure d r i v e n membrane processes o f f e r i n the t r e a t i n g v i r g i n must. Polyphenol and p r o t e i n concentrations can be c o n t r o l l e d without a f f e c t i n g the sugar content. The u l t r a f i l t e r e d must can be concentrated by reverse osmosis w i t h membranes up to 100% r e j e c t i o n f o r sugars. C u and Z n c a t i o n s could be e x t r a c t e d from the concentrated must. + +

+ +

F l u x decays and r e j e c t i o n changes i n the UF s t e p s , depending upon the feed c o n c e n t r a t i o n and experiment h i s t o r y , must be mainly a t t r i b u t e d to c o n c e n t r a t i o n p o l a r i z a t i o n phenomena w i t h consequent gel l a y e r formation of the p r e s s u r i z e d membrane s u r f a c e , f o r the presence of p r o t e i n s , c o l l o i d s and i n general h i g h molecular species i n the feed ( 3 ) .

LITERATURE CITED 1.

Crull A.W., "The e v o l v i n g membrane market" P.041 Communications CO., I n c . , Conn.USA

Business

2. Dinsmoor Webb A., Chemistry of Winemaking", A.C.S. Advances i n Chem.Series 137, Washington DC (1974) 3.

Drioli, E., Dynamically formed and t r a n s i e n t membranes" i n "Recent Advances in Separation Science", Ed.N.N.Li, v o l . 3 , CRC Press I n c . , (1977), p.343

4.

Drioli, E., " P o l a r i z z a z i o n e per concentrazione" in "Ricerche s u l processo ad osmosi i n v e r s a " , Quaderni IRSA, C.N.R., vol.22 (1977), p.177.

RECEIVED

February 18,

1981.


Synthetic Membranes - American Chemical Society

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