- Email: [email protected]
Inert gas : safeguard of quality
VACUUM Classified A b s t r a c t s III
--
Vacuum
Processing Techniques --
III
Contd.
59/Iii
Greaseless Stopcock for Use at Sub-Atmospheric Pressures See A b s t r a c t No. : 3 5 / I I
39 - - M I S C E L L A N E O U S
O
O
Abstract ~o. and References
P R O C E S S E S - - 39
Rapid Heat Processing of Fluid Foods by Steam Injection United States. I n order to i m p r o v e e x i s t i n g m e t h o d s for s h o r t - t i m e h i g h - t e m p e r a t u r e h e a t processing a n d c o n c e n t r a t i o n of fluid foods, s u c h as f r u i t a n d v e g e t a b l e juices, a n e w t y p e of e q u i p m e n t h a s b e e n developed a n d t h e r e s u l t s of its o p e r a t i o n o n a pilot p l a n t scale are described. T h e p l a n t consists e s s e n t i a l l y of a preheater, a s t e a m injection h e a t e r supplied w i t h clean s t e a m , a c o m b i n a t i o n e v a p o r a t o r a n d a v a p o u r liquid separator. T h e t w o m a i n f e a t u r e s of t h e e q u i p m e n t a r e t h e s t e a m injection h e a t e r a n d t h e c o m b i n a t i o n evaporator. T h e injection h e a t e r is m a d e f r o m a 12 i n c h l e n g t h of 3 / 8 t h i n c h i.p.s, s t a i n l e s s steel pipe a n d consists e s s e n t i a l l y of t h e following c o m p o n e n t s : p r o d u c t inlet tube, h e a t e r b o d y fitted w i t h a t h e r m o c o u p l e , discharge orifice a n d p r o d u c t o u t l e t t u b e . T h e s t e a m is a d m i t t e d to t h e h e a t e r b o d y t a n g e n t i a l l y . T h i s a p p a r a t u s p r e h e a t s or s u p e r h e a t s t h e processed m a t e r i a l before it e n t e r s t h e e v a p o r a t o r . T h e l a t t e r consists of a s t e a m j a c k e t t e d t u b e m a d e f r o m s t a i n l e s s steel ½ i n c h i.p.s, a n d 6 ft. long. T h e m a t e r i a l r e a c h i n g t h e e v a p o r a t o r is c o n c e n t r a t e d b y e v a p o r a t i v e cooling a t a p r e s s u r e below its v a p o u r p r e s s u r e a t t h e t e m p e r a t u r e p r e v a i l i n g in t h e injection h e a t e r . T h e a m o u n t of w a t e r e v a p o r a t e d is p r o p o r t i o n a l to t h e h e a t w h i c h h a s to be r e m o v e d in order to cool t h e m a t e r i a l d o w n to its v a p o u r - l i q u i d e q u i l i b r i u m t e m p e r a t u r e in t h e s e p a r a t o r . T h e c o m b i n a t i o n e v a p o r a t o r a n d s t e a m injection h e a t e r are o p e r a t e d as c o n t i n u o u s processing units. F o r t h e p a s t e u r i s a t i o n of milk, r a w m i l k w a s processed in t h e p l a n t , i.e. it w a s h e a t e d . t * 2 4 5 ° F in t h e injection h e a t e r a n d cooled e v a p o r a t i v e l y to 80°F, t h e whole process n o t t a k i n g longer t h a n 0.7 seconds. T h e r a w m i l k w a s c o n c e n t r a t e d f r o m 11.4% to 2 6 . 0 % solids in a single p a s s t h r o u g h t h e c o m b i n a t i o n e v a p o r a t o r w i t h t h e injection h e a t e r o p e r a t i n g a t 2 4 4 ° F a n d t h e e v a p o r a t o r k e p t u n d e r low pressure. T h e e n z y m e p h o s p h a t a s e in r a w m i l k was f o u n d to b e i n a c t i v a t e d b y h e a t i n g t h e milk to 185°F a n d cooling e v a p o r a t i v e l y to 95°F in a t o t a l t i m e of 0.4 seconds. R e s u l t s w i t h o t h e r food m a t e r i a l s a r e also given. Sommaire : C o m p t e . r e n d u des r6su~tats o b t e n u s p a r u n e i n s t a l l a t i o n d ' e s s a i d ' u n n o u v e a u proc6d6 de c h a u f f a g e rapide, p a r injectiol~ de v a p e u r , de p r o d u i t s a l i m e n t a i r e s fluides. Inert Gas : Safeguard of Quality United States. N i t r o g e n processing a n d p a c k a g i n g in t h e food i n d u s t r y is n o t n e w b u t its i m p o r t a n c e is still growing. N i t r o g e n gas c a n be u s e d in processing a n d p a c k a g i n g of foods like edible oils, m a r g a r i n e , coffee, dried a c t i v a t e d yeast, n u t m e a t s , s a n d w i c h m e a t s , bacon, s a u s a g e s , d e h y d r a t e d p o t a t o e s , etc. T h e p r o p e r p r o t e c t i o n of food p r o d u c t s d e p e n d s e s s e n t i a l l y o n t h e effectiveness w i t h w h i c h o x y g e n c a n be k e p t o u t or r e m o v e d f r o m t h e container. T h e a t m o s p h e r i c air consists of a b o u t 1 / S t h of o x y g e n , t h e r e m a i n d e r is m a i n l y nitrogen. T h i s n ~ a n s t h a t b r e a k i n g b a c k a v a c u u m w i t h n i t r o g e n does n o t reduce t h e a m o u n t of o x y g e n p r e s e n t a n d it is i m p o r t a n t t h e r e f o r e to use n i t r o g e n of e x t r e m e p u r i t y only. If the p r o d u c t is u n s t a b l e a n d p e r s i s t e n t l y releases dissolved o x y g e n , p a c k a g i n g in v a c u u m or p r o v i d i n g n i t r o g e n h e a d space is n o t t h e c o m p l e t e solution. F o r e x a m p l e , a p r o d u c t c o n t a i n s a b o u t 0.6 c m ~ of dissolved o x y g e n in e v e r y h u n d r e d c m a of liquid a n d t h e c o n t a i n e r is designed to allow for a h e a d space of 10%. If p a c k e d w i t h air in t h e h e a d s p a c e t h e t o t a l o x y g e n c o n t e n t will be a b o u t 2.95 c m a p e r 100 c m a of liquid. O n l y b y p u r g i n g t h e h e a d space w i t h n i t r o g e n or b y n i t r o g e n s t r i p p i n g c a n t h i s figure be r e d u c e d to 0.8 c m 3. I t is i m p o r t a n t to h a v e a c c u r a t e k n o w l e d g e of t h e r a t e a t w h i c h o x y g e n diffuses t h r o u g h a film u s e d for p a c k a g i n g . E v e n if t h e film is free of p i n holes a n d h a s good sealing p r o p e r t i e s o x y g e n c a n be t r a n s f e r r e d b y diffusion d u e to t h e difference b e t w e e n t h e p a r t i a l p r e s s u r e of o x y g e n inside t h e p a c k a g e a n d t h e s u r r o u n d i n g a t m o s p h e r e . A p r o d u c t p a c k e d in v a c u u m m a y a p p e a r to be g a s - t i g h t b u t unless t h e film possesses a n i n h e r e n t l y low o x y g e n p e r m e a b i l i t y , p r o d u c t d e t e r i o r a t i o n b y chemical a b s o r p t i o n of diffused o x y g e n c a n occur w i t h o u t a p p a r e n t c h a n g e of pressure. Sommaire : Discussion des diverses formes d ' a p p l i c a t i o n d ' a z o t e d a n s l ' e m p a q u e t a g e des p r o d u i t s alimentaires.
6o/m
Article by A. It. Brown M. E. Lazar T. Wasserman G. S. Snfith & W. M. Cole Industr. Eng~g. Chem. 43, Dec. 1951 2949-2954
61/II
Article by T. W. Eselgroth Food Engng. 23, Dec. 1951 72-75, 153 & 155
Frozen Concentrated Apple Juice See A b s t r a c t No. : 3 1 / I I I
62/111
Costs and Methods for Pie-Stock Apples United States. T h e cost of s u p p l y of p i e - s t o c k apples to a d i s t a n t m a r k e t is influenced m a i n l y b y two considerations : w e i g h t a n d v o l u m e of t h e p a c k a g e d p r o d u c t a n d t h e s t o r a g e a n d t r a n s p o r t conditions required. T h e W e s t e r n R e g i o n a l R e s e a r c h L a b o r a t o r y h a v e compiled cost e s t i m a t e s to p r o v i d e a n e c o n o m i c f o u n d a t i o n on w h i c h to b a s e l a b o r a t o r y w o r k o n i m p r o v e d processes. T h e Pacific S t a t e s a r e g r o w i n g m o r e apples t h a n c a n be c o n s u m e d locally a n d are compelled to sell t h e i r s u r p l u s in E a s t e r n m a r k e t s . T h e article gives t h e relative costs of s u p p l y i n g E a s t e r n m a r k e t s w i t h W e s t e r n a p p l e s processed b y v a r i o u s m e t h o d s . T h e following processes are t a k e n into a c c o u n t : (1) Dried. (2) V a c u u m Dried. (3) D e h y d r o c a n n e d . (4) C a n n e d . (5) D e h y d r o f r o z e n .
63fill
J a n u a r y , /952
Vacuum VoL I I No. 7
97
--
Vacuum
Processing Techniques --
III
Contd.
59/Iii
Greaseless Stopcock for Use at Sub-Atmospheric Pressures See A b s t r a c t No. : 3 5 / I I
39 - - M I S C E L L A N E O U S
O
O
Abstract ~o. and References
P R O C E S S E S - - 39
Rapid Heat Processing of Fluid Foods by Steam Injection United States. I n order to i m p r o v e e x i s t i n g m e t h o d s for s h o r t - t i m e h i g h - t e m p e r a t u r e h e a t processing a n d c o n c e n t r a t i o n of fluid foods, s u c h as f r u i t a n d v e g e t a b l e juices, a n e w t y p e of e q u i p m e n t h a s b e e n developed a n d t h e r e s u l t s of its o p e r a t i o n o n a pilot p l a n t scale are described. T h e p l a n t consists e s s e n t i a l l y of a preheater, a s t e a m injection h e a t e r supplied w i t h clean s t e a m , a c o m b i n a t i o n e v a p o r a t o r a n d a v a p o u r liquid separator. T h e t w o m a i n f e a t u r e s of t h e e q u i p m e n t a r e t h e s t e a m injection h e a t e r a n d t h e c o m b i n a t i o n evaporator. T h e injection h e a t e r is m a d e f r o m a 12 i n c h l e n g t h of 3 / 8 t h i n c h i.p.s, s t a i n l e s s steel pipe a n d consists e s s e n t i a l l y of t h e following c o m p o n e n t s : p r o d u c t inlet tube, h e a t e r b o d y fitted w i t h a t h e r m o c o u p l e , discharge orifice a n d p r o d u c t o u t l e t t u b e . T h e s t e a m is a d m i t t e d to t h e h e a t e r b o d y t a n g e n t i a l l y . T h i s a p p a r a t u s p r e h e a t s or s u p e r h e a t s t h e processed m a t e r i a l before it e n t e r s t h e e v a p o r a t o r . T h e l a t t e r consists of a s t e a m j a c k e t t e d t u b e m a d e f r o m s t a i n l e s s steel ½ i n c h i.p.s, a n d 6 ft. long. T h e m a t e r i a l r e a c h i n g t h e e v a p o r a t o r is c o n c e n t r a t e d b y e v a p o r a t i v e cooling a t a p r e s s u r e below its v a p o u r p r e s s u r e a t t h e t e m p e r a t u r e p r e v a i l i n g in t h e injection h e a t e r . T h e a m o u n t of w a t e r e v a p o r a t e d is p r o p o r t i o n a l to t h e h e a t w h i c h h a s to be r e m o v e d in order to cool t h e m a t e r i a l d o w n to its v a p o u r - l i q u i d e q u i l i b r i u m t e m p e r a t u r e in t h e s e p a r a t o r . T h e c o m b i n a t i o n e v a p o r a t o r a n d s t e a m injection h e a t e r are o p e r a t e d as c o n t i n u o u s processing units. F o r t h e p a s t e u r i s a t i o n of milk, r a w m i l k w a s processed in t h e p l a n t , i.e. it w a s h e a t e d . t * 2 4 5 ° F in t h e injection h e a t e r a n d cooled e v a p o r a t i v e l y to 80°F, t h e whole process n o t t a k i n g longer t h a n 0.7 seconds. T h e r a w m i l k w a s c o n c e n t r a t e d f r o m 11.4% to 2 6 . 0 % solids in a single p a s s t h r o u g h t h e c o m b i n a t i o n e v a p o r a t o r w i t h t h e injection h e a t e r o p e r a t i n g a t 2 4 4 ° F a n d t h e e v a p o r a t o r k e p t u n d e r low pressure. T h e e n z y m e p h o s p h a t a s e in r a w m i l k was f o u n d to b e i n a c t i v a t e d b y h e a t i n g t h e milk to 185°F a n d cooling e v a p o r a t i v e l y to 95°F in a t o t a l t i m e of 0.4 seconds. R e s u l t s w i t h o t h e r food m a t e r i a l s a r e also given. Sommaire : C o m p t e . r e n d u des r6su~tats o b t e n u s p a r u n e i n s t a l l a t i o n d ' e s s a i d ' u n n o u v e a u proc6d6 de c h a u f f a g e rapide, p a r injectiol~ de v a p e u r , de p r o d u i t s a l i m e n t a i r e s fluides. Inert Gas : Safeguard of Quality United States. N i t r o g e n processing a n d p a c k a g i n g in t h e food i n d u s t r y is n o t n e w b u t its i m p o r t a n c e is still growing. N i t r o g e n gas c a n be u s e d in processing a n d p a c k a g i n g of foods like edible oils, m a r g a r i n e , coffee, dried a c t i v a t e d yeast, n u t m e a t s , s a n d w i c h m e a t s , bacon, s a u s a g e s , d e h y d r a t e d p o t a t o e s , etc. T h e p r o p e r p r o t e c t i o n of food p r o d u c t s d e p e n d s e s s e n t i a l l y o n t h e effectiveness w i t h w h i c h o x y g e n c a n be k e p t o u t or r e m o v e d f r o m t h e container. T h e a t m o s p h e r i c air consists of a b o u t 1 / S t h of o x y g e n , t h e r e m a i n d e r is m a i n l y nitrogen. T h i s n ~ a n s t h a t b r e a k i n g b a c k a v a c u u m w i t h n i t r o g e n does n o t reduce t h e a m o u n t of o x y g e n p r e s e n t a n d it is i m p o r t a n t t h e r e f o r e to use n i t r o g e n of e x t r e m e p u r i t y only. If the p r o d u c t is u n s t a b l e a n d p e r s i s t e n t l y releases dissolved o x y g e n , p a c k a g i n g in v a c u u m or p r o v i d i n g n i t r o g e n h e a d space is n o t t h e c o m p l e t e solution. F o r e x a m p l e , a p r o d u c t c o n t a i n s a b o u t 0.6 c m ~ of dissolved o x y g e n in e v e r y h u n d r e d c m a of liquid a n d t h e c o n t a i n e r is designed to allow for a h e a d space of 10%. If p a c k e d w i t h air in t h e h e a d s p a c e t h e t o t a l o x y g e n c o n t e n t will be a b o u t 2.95 c m a p e r 100 c m a of liquid. O n l y b y p u r g i n g t h e h e a d space w i t h n i t r o g e n or b y n i t r o g e n s t r i p p i n g c a n t h i s figure be r e d u c e d to 0.8 c m 3. I t is i m p o r t a n t to h a v e a c c u r a t e k n o w l e d g e of t h e r a t e a t w h i c h o x y g e n diffuses t h r o u g h a film u s e d for p a c k a g i n g . E v e n if t h e film is free of p i n holes a n d h a s good sealing p r o p e r t i e s o x y g e n c a n be t r a n s f e r r e d b y diffusion d u e to t h e difference b e t w e e n t h e p a r t i a l p r e s s u r e of o x y g e n inside t h e p a c k a g e a n d t h e s u r r o u n d i n g a t m o s p h e r e . A p r o d u c t p a c k e d in v a c u u m m a y a p p e a r to be g a s - t i g h t b u t unless t h e film possesses a n i n h e r e n t l y low o x y g e n p e r m e a b i l i t y , p r o d u c t d e t e r i o r a t i o n b y chemical a b s o r p t i o n of diffused o x y g e n c a n occur w i t h o u t a p p a r e n t c h a n g e of pressure. Sommaire : Discussion des diverses formes d ' a p p l i c a t i o n d ' a z o t e d a n s l ' e m p a q u e t a g e des p r o d u i t s alimentaires.
6o/m
Article by A. It. Brown M. E. Lazar T. Wasserman G. S. Snfith & W. M. Cole Industr. Eng~g. Chem. 43, Dec. 1951 2949-2954
61/II
Article by T. W. Eselgroth Food Engng. 23, Dec. 1951 72-75, 153 & 155
Frozen Concentrated Apple Juice See A b s t r a c t No. : 3 1 / I I I
62/111
Costs and Methods for Pie-Stock Apples United States. T h e cost of s u p p l y of p i e - s t o c k apples to a d i s t a n t m a r k e t is influenced m a i n l y b y two considerations : w e i g h t a n d v o l u m e of t h e p a c k a g e d p r o d u c t a n d t h e s t o r a g e a n d t r a n s p o r t conditions required. T h e W e s t e r n R e g i o n a l R e s e a r c h L a b o r a t o r y h a v e compiled cost e s t i m a t e s to p r o v i d e a n e c o n o m i c f o u n d a t i o n on w h i c h to b a s e l a b o r a t o r y w o r k o n i m p r o v e d processes. T h e Pacific S t a t e s a r e g r o w i n g m o r e apples t h a n c a n be c o n s u m e d locally a n d are compelled to sell t h e i r s u r p l u s in E a s t e r n m a r k e t s . T h e article gives t h e relative costs of s u p p l y i n g E a s t e r n m a r k e t s w i t h W e s t e r n a p p l e s processed b y v a r i o u s m e t h o d s . T h e following processes are t a k e n into a c c o u n t : (1) Dried. (2) V a c u u m Dried. (3) D e h y d r o c a n n e d . (4) C a n n e d . (5) D e h y d r o f r o z e n .
63fill
J a n u a r y , /952
Vacuum VoL I I No. 7
97