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Single Cell Protein and the Protein Economy JEREMY J. WELLS Biochem Design S.p.A., Via A. Bargoni 78 - 00153 Rome, Italy
The p r i m a r y a i m o f t h i s p a p e r i s t o e x a m i n e c a r b o h y d r a t e s as p o t e n t i a l s u b s t r a t e s f o r t h e p r o d u c t i o n o f s i n g l e c e l l p r o t e i n (SCP) a n d c o m p a r e t h e m w i t h o t h e r s u b s t r a t e s such as h y d r o c a r b o n s . An o v e r v i e w o f a c t u a l and p o t e n t i a l s u p p l i e s o f p r o t e i n f r o m v a r i o u s s o u r c e s i s n e c e s s a r y t o show t h e r e q u i r e m e n t s o f SCP i n t h e p r o t e i n s u p p l e m e n t market. D e v e l o p m e n t o f t h e p r e s e n t s t a t u s o f SCP p r o j e c t s shows t h e c h a n g e s d u r i n g t h e p a s t y e a r . Man j u d g e s h i s s t a n d a r d o f l i v i n g b y h i s c o n s u m p t i o n o f h i g h p r o t e i n s s u c h as m e a t m i l k and eggs. To p r o d u c e t h e s e h i g h p r o t e i n s , r e q u i r e s a l a r g e a n d complex animal f e e d i n d u s t r y which today not o n l y i s w e l l developed but highly sophisticated. Protein supplements are produced m a i n l y because a l a r g e market f o r them e x i s t s . The r o l e o f SCP a s a p r o t e i n s u p p l e m e n t , h a s become w e l l e s t a b l i s h e d o v e r t h e l a s t f e w years. L a r g e amounts o f n u t r i t i o n a l and t o x i c o l o g i c a l d a t a have p r o v i d e d numerous government r e g u l a t o r y aut h o r i t i e s s u f f i c i e n t evidence to give product approval i n many d e v e l o p e d c o u n t r i e s . I t h a s b e e n e s t a b l i s h e d c l e a r l y t h a t SCP i s a n e x c e l l e n t source of p r o t e i n f o r animal feeding. Howe v e r , a t t h i s t i m e t h e p r o d u c t i o n o f SCP s t i l l i s n o t c o m m e r c i a l l y v i a b l e on a c c o u n t o f t h e ample s u p p l i e s o f p r o t e i n s a v a i l a b l e a t p r i c e s l o w e r t h a n SCP c a n be produced. The h o p e s f o r h a v i n g t w o m a j o r p r o d u c t i o n u n i t s i n o p e r a t i o n d u r i n g 1976 h a v e b e e n d a m p e n e d now b y p o l i t i c a l b a n s , b r o u g h t on b y I t a l i a n consumer g r o u p s , on t h e two m a i n p r o c e s s o r s , I t a l p r o t e i n e a n d L i q u i c h i m i c a S.p. A. D e v e l o p m e n t o f t e c h n o l o g y t o p r o d u c e SCP f r o m c e l l u l o s e remains commercially e l u s i v e . However, i n view o f the expected l i f e span of hydrocarbon r e s o u r c e s , f
f
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Hickson; Sucrochemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
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SUCROCHEMISTRY
most e x p e r t s agree t h a t c a r b o h y d r a t e s c o u l d h o l d the g r e a t e s t p o t e n t i a l f o r f u t u r e SCP d e v e l o p m e n t , s i n c e they are renewable resources. Yet,the economics of u s i n g c a r b o h y d r a t e s u b s t r a t e s o f t e n a r e r a t h e r p o o r on a c c o u n t o f many c o n s t r a i n t s o n t h e i r u s e . S t a t u s o f SCP
Developments
The p r o m i s e o f a 2 0 0 , 0 0 0 t o n SCP p r o d u c t i o n d u r i n g 1976 was s h a t t e r e d b y t h e s u s p e n s i o n b y C o n s i g l i o S u p e r i o r e d i S a n i t a i n Rome o f t h e i r p r e v i o u s d e c r e e t o I t a l p r o t e i n e , a u t h o r i s i n g t h e u s e o f SCP i n I t a l y . T h i s h a s m e a n t t h a t t h e p l a n t s o f b o t h I t a l p r o t e i n e and L i q u i c h i m i c a S . p . A . , a l t h o u g h f i n i s h e d , c a n n o t be o p e r a ted, except f o r l i m i t e d , t e s t purposes. B r i t i s h P e t r o l e u m h a s s t a t e d p u b l i c l y t h a t no t e c h n i c a l reason e x i s t s t o w i t h h o l d permission f o r the use o f t h e i r p r o d u c t . C o n f i r m a t i o n by w e i g h t y f a c t u a l e v i d e n c e s u b m i t t e d f r o m a l l p a r t s o f t h e w o r l d makes this factual. B r i t i s h P e t r o l e u m , w i t h o v e r $60 m i l l i o n t i e d up i n p l a n t , n o w i s a t t e m p t i n g a j u d i c i a l a p p e a l . Although the f i n a n c i a l prospects are poor f o r operating these p l a n t s i n the c u r r e n t p r o t e i n supplement markets, they are expected t o y i e l d v i t a l o p e r a t i n g data f o r future developments. This i s important, since several o i l p r o d u c i n g c o u n t r i e s a r e s t u d y i n g SCP p r o d u c t i o n a s a means o f a d d i n g v a l u e t o t h e i r o i l r e s o u r c e s . In the l a s t y e a r , s e v e r a l major groups have w i t h d r a w n f r o m SCP d e v e l o p m e n t s i n c l u d i n g S h e l l C h e m i c a l a n d t h e F r e n c h , CFR g r o u p . A t t h e same t i m e , I m p e r i a l Chemical I n d u s t r i e s L t d . (ICI) have postponed a u t h o r i z a t i o n f o r t h e i r major production u n i t . It even i s rumored t h a t they c u t i t s p r o j e c t e d s i z e t o 50,000 t o n s b e f o r e p r e s e n t a t i o n t o t h e i r B o a r d . On the s u c c e s s f u l c o m p l e t i o n o f the I C I p l a n t , depends p o t e n t i a l d e v e l o p m e n t s i n I r a n and J a p a n . However, t h e s i t u a t i o n i n E a s t E u r o p e i s more o p t i m i s t i c . In these c o u n t r i e s , e c o n o m i c v i a b i l i t y i s enhanced by t h e a n t i cipated savings i n hard currency. The G o v e r n m e n t o f t h e USSR c u r r e n t l y i s d i s c u s s i n g w i t h s e v e r a l p r o c e s s o r s , t h e d e v e l o p m e n t o f a 250,000 ton p l a n t . T h i s makes s e n s e i n a c o u n t r y s u c h as R u s s i a n w h i c h i m p o r t s l a r g e amounts o f f e e d supplements for d o l l a r s , while n - p a r a f f i n s are a n a t u r a l resource. A j o i n t v e n t u r e b e t w e e n t h e Governments o f P o l a n d and E a s t Germany i s e x p e c t e d t o p r o d u c e a 5 0 , 0 0 0 t o n p l a n t u s i n g a gas o i l s u b s t r a t e . And, t h e 60,000 t o n , j o i n t J a p a n e s e and Romanian p l a n t i s a l m o s t on s t r e a m . A n o t h e r o i l p r o d u c e r i n t e n d i n g t o p r o d u c e SCP, i s V e n e z u e l a , where a 100,000 t o n p l a n t c u r r e n t l y i s b e i n g
Hickson; Sucrochemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
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WELLS
Single Cell Protein
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b u i l t , based on B r i t i s h Petroleum technology. I t i s t o be c o m p l e t e d b y 1979. Five other o i l producers, A f g a n i s t a n , A l g e r i a , L i b y a , Kuwait and Saudi A r a b i a a r e s t u d y i n g the e x e c u t i o n o f p r e - f e a s i b i l i t y s t u d i e s v i a t h e o f f i c e s o f t h e U n i t e d N a t i o n s (UNIDO). I ti s r e p o r t e d t h a t o v e r $ 1 4 0 m i l l i o n o f A r a b i a n OPEC money may h a v e b e e n p u t a s i d e f o r n o v e l , p e t r o c h e m i c a l d e v e l opments. T a b l e I comments o n t h e p r e s e n t s t a t u s o f p r o j e c t s l a s t r e p o r t e d i n 1975 d u r i n g t h e A m e r i c a n C h e m i c a l S o ciety's S y m p o s i u m o n SCP i n P h i l a d e l p h i a . One c a n g e n e r a l i z e , s a y i n g t h a t , i n a d e v e l o p e d c o u n t r y e n v i r o n m e n t , SCP f r o m h y d r o c a r b o n s i s n o t comm e r c i a l l y v i a b l e a t t h i s t i m e . However, i n c e r t a i n l i m i t e d circumstances, i nc o u n t r i e s w i t h low raw m a t e r i a l c o s t s , w i t h l o w u t i l i t i e s c o s t s , o r where h a r d c u r r e n c y i s s c a r c e , SCP o f t e n c a n b e j u s t i f i e d e c o n o m i c a l l y . B r i t i s h P e t r o l e u m and I C I have m a i n t a i n e d programs to o b t a i n r e g u l a t o r y p e r m i s s i o n o f t h e i r products through extensive t e s t i n g . T h i s h a s been s u c c e s s f u l throughout Europe w i t h the notable e x c e p t i o n o f I t a l y . Potential
f o r Carbohydrate
Substrates
T h e r e h a s b e e n a l o n g s e a r c h f o r a n e c o n o m i c means of producing n u t r i e n t s from carbohydrate s u b s t r a t e s . I n G e r m a n y d u r i n g W o r l d War I I , y e a s t s w e r e p r o d u c e d o n wood s u g a r s o b t a i n e d b y h y d r o l y s i s o f wood w a s t e s . However, t h e s e uneconomic p r o c e s s e s w i l l n o t be v i a b l e i n a f r e e economy. I n t h eS o v i e t Union today, over 9 0 0 , 0 0 0 t o n s o f f o d d e r y e a s t a r e p r o d u c e d f r o m wood sugars. S e v e r a l major p r o c e s s o r s have been t r y i n g to d e v e l o p a d i r e c t f e r m e n t a t i o n o f c e l l u l o s e . However, slow r e a c t i o n t i m e s and l o w c e l l y i e l d s have caused most p r o c e s s e s t o be u n e c o n o m i c a l . C a r b o h y d r a t e s c a n be c l a s s i f i e d i n t o two c l a s s e s for t h i s d i s c u s s i o n . Saccharides and p o l y s a c c h a r i d e s w i l l be d i s c u s s e d s e p a r a t e l y . There i s an obvious a t t r a c t i o n i nu s i n g an annuall y renewable resource. However t h e e c o n o m i c s o f p r o duction often i s n o t appreciated i n which every potent i a l s u b s t r a t e must be c o n s i d e r e d i n terms o f : - A l t e r n a t i v e use - Logistics of collection - Degree o f p r e t r e a t m e n t , and - Seasonal availability. Table I I l i s t s the p o s s i b l e p o t e n t i a l substrates with their various restraints. Most c a r b o h y d r a t e s , p a r t i c u l a r l y c o n v e n t i o n a l n u t r i t i o n a l ones, have c o n s i d e r a b l e market v a l u e . In
Hickson; Sucrochemistry ACS Symposium Series; American Chemical Society: Washington, DC, 1977.
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