University of Southern California Dissertations and Theses

The dehydration of vegetables

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The dehydration of vegetables

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Content THE DEHYDRATION OF VEGETABLES A T h e sis P re s e n te d to th e D epartm ent o f C hem istry U n iv e r s ity o f S o u th e rn C a lif o r n i a In p a r t i a l f u l f i l l m e n t o f t h e R e q u irem en ts f o r th e D egree o f M aster o f A rts By L ow ell R . D ailey Ju n e 1935 < rp UMI Number: EP41478 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. UMI EP41478 Published by ProQuest LLC (2014). Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 This thesis, written under the direction of the candidate’s Faculty Com m ittee and approved by all its members, has been presented to and ac cepted by the Council on Graduate Study and Research in partial fulfillment of the require m ents for the degree of Mas.t.er...c£..S.c>.iaix<?.e...................................................... y ^ . Secretary Dean D a t e . A u ® * st*. 1935 Facultv Committee Chairman T V TABLE O F CONTENTS CHAPTER Page INTRODUCTION ................................................................................ i i I . DEHYDRATIOH A. M ETHODS IN DEHYDRATION OF VEGETABLES . . . 1 B. EXPERIMENTAL PR0CS2DUR2 A N D RESULTS . . . 7 C. PULVERIZATION OF DEHYDRATED VEGETABLES . . 22 I I . A STUDY OF DEHYDRATED VEGETABLES A. THEORY OF BUFFERS ...................................................... 23 B. EXPERIMENTAL W O R K O N BUFFER ACTION OF DE HYDRATED VEGETABLES 33 I I I . SU M M A R Y A N D CONCLUSIONS .................................................... 61 IV . BIBLOGRAPHY A. BIBLOGRAPHY O N DEHYDRATION....................... 63 B. BIBLOGRAPHY O N B U F F E R S ................................ 64 INTRODUCTION i i Most v e g e ta b le s a r e com posed l a r g e l y o f w a te r . S pinach a s a r e p r e s e n t a t i v e o f th e l e a f y ty p e i s 9 3 .7 p e r c e n t w a te r, and c a r r o t s , a r e p r e s e n t a t i v e o f th e f le s h y ro o t ty p e i s 8 8 .3 p e r c e n t w a te r . T h ere a r e s e v e r a l a d v a n ta g e s in rem oving th e w a te r from th e v e g e ta b le s , a s in th e p r e p a r a tio n o f d e h y d ra te d v e g e t a b l e s : 1 . The le n g th o f tim e w hich th e v e g e ta b le s may be s to r e d i s in c r e a s e d from a few day s t o many m o n th s, s in c e th e r e i s n o t enough w a te r p r e s e n t t o a llo w th e a g e n c ie s o f decay t o f u n c tio n . 3 . T r a n s p o r ta tio n i s made much e a s i e r due t o th e f a c t t h a t th e e le m e n ts o f tim e , b r u s in g , an d c o s t o f r e - f r i g i d e r a t i o n a r e o f l i t t l e im p o rta n c e . The ex p en se i s c u t down v e ry much i n t h a t one to n o f f r e s h v eg e t a b l e s c o n ta in s a b o u t 1800 pounds o f w a te r w h ile one to n o f d e h y d ra te d v e g e ta b le s c o n ta in s o n ly 100 pounds o f w a te r. 3 . The p la n t c e l l s a r e made v ery b r i t t l e , th u s e n a b lin g com m ercial p u lv e r iz a ti o n t o a f i n e degree., w hich makes much more a v a i l a b l e th e fo o d m a te r ia l w ith in th e c e l l s t r u c t u r e . Some o f th e p ro d u c ts th u s f r e e d may a l s o a c t a s b u f f e r s i n p ro d u c in g an a c i d o r b ase n e u t r a l i z i n g pow er. i i i D uring th e w o rld war th e q u e s tio n o f t r a n s p o r t a t i o n and s a f e s to r a g e o f v e g e ta b le s was an im p o rta n t o n e . Many d e h y d ra tio n m ethods w ere d ev e lo p e d a s a r e s u l t o f th o s e tr y i n g tim e s , in an a tte m p t t o overcome th e s e p ro b le m s. Some com m ercial work dome s in c e th e n h a s g iv e n u s many v a lu a b le p r o d u c ts . The p u rp o se o f t h i s i n v e s t i g a t i o n i s t o make a stu d y o f th e d e h y d ra te d p r o d u c ts . CHAPTER I DEHYDRATION A. M ETHODS IN DEHYDRATION OF VEGETABLES D eh y d rated p r o d u c ts , a s d is tin g u is h e d from e v a p o ra te d f r u i t s and v e g e ta b le s a r e d e f in e d a s th o s e c o n ta in in g p r a c t i c a l l y no w a te r and h av in g t h e i r o r ig i n a l f l a v o r and t e x t u r e . 1 E x p erim en ts c a r r i e d on by M angels an d Gore a t th e U* S . D ep t, o f A g r ic u ltu r e 3 showed t h a t te m p e ra tu re s above 7 0 ° C. w ere h a rm fu l. F o r te m p e ra tu re s below 70° C. th e i n ju r y end p o in t c o u ld n o t be a s r e a d i l y re c o g n iz e d , b u t th e r e a p p e a re d to b e a v e ry g ra d u a l change i n th e p r o d u c t. A te m p e ra tu re o f 55° C. was n o t h arm fu l even to th e m ost s e n s i t i v e v e g e ta b l e s . Dry h e a t seemed to be l e s s h arm fu l th a n when th e h u m id ity was h i g h e r . V e g e ta b le s a r e c l a s s i f i e d a s fo llo w s i n re g a rd t o * 2 s e n s i t i v e n e s s : 1 G. V . E k ro th , J . o f P u b lic H e a lth . 1918, V o l. 8, p p . 305— 7 . 3 0 . S . M angels an d J . C. G ore, I n d . E ng. Chem. , 1931, V o l. 1 3 , p . 535. 3 L o c. G it. 3 V ery e a s i l y in ju r e d .: O nions, t u r n i p s , c e le r y , to m a to e s, c a b b a g e . F a i r l y r e s i s t a n t : Sweet c o m , w h ite p o ta to e s , c a r r o t s , s t r i n g b e a n s . V ery r e s i s t a n t : Sweet p o t a t o e s . As th e d eg ree o f te m p e ra tu re i s in c r e a s e d , th e tim e n e c e s s a ry t o c a u se in j u r y d e c r e a s e s . In th e work o f M angels and G ore * i t was shown t h a t raw d r ie d v e g e ta b le s d e t e r i o r a t e - o n s to r a g e in a i r t i g h t con— a i n e r s a t o rd in a ry te m p e ra tu re s u n le s s th e w a te r c o n te n t i s below a c e r t a i n p o i n t . The c r i t i c a l w a te r c o n te n t, below w hich c o lo r an d f l a v o r a r e w e ll r e ta in e d f o r s i x m onths, a r e o a r r o t s 4 .9 9 - 7 .3 9 p e r c e n t, t u r n i p s 5 .0 0 p e r c e n t, s p in a c h 3 .8 1 -5 .3 8 p e r c e n t, an d cabbage 3 .0 0 -3 .3 4 p e r c e n t . I n a n o th e r ex p erim en t by th e same men ^ a steam h e a te d com m ercial d ry e r w as u s e d . A s u b s t a n t i a l q u a n tity o f each v e g e ta b le was c u t f i n e l y , s p re a d on t r a y s , an d d r ie d i n a c u r r e n t o f warm a i r . Sam ples w ere ta k e n o u t a t i n t e r v a l s and s to r e d f o r d i f f e r e n t le n g th s o f tim e w ith th e fo llo w in g r e s u l t s a s shown i n t a b l e s on n e x t p a g e . 1 Q e . c i t .. p p . 5 3 3 -4 . 2 L o c. c i t . 3 TABLE A CARROTS A, DRIED 6 HOURS AT 132° F . ; B, 6 HOURS AT 133° F . PLUS 3 HOURS AT 140° F . j C, 6 HOURS AT 1 3 2 ° F . PLUS 3 HOURS AT 140° F . Days S to ra g e A 1 1 .1 p e r c e n t w a te r B 7 .3 9 p e r c e n t w a te r C 4 .99 p e r c e n t w a te r 86 C o lo r fa d e d odor an d f l a v o r s t i l l d i s t i n c t i v e C o lo r s l i g h t l y fa d e d No change 335 C a rro t c o l o r f ade& . Sample d a rk en ed C o lo r f a d e d . No d ark en in g o d o r and f l a v o r s t i l l d i s t i n c t i v e C o lo r fa d e d s l i g h t l y l e s s th a n B 690 C o lo r fa d e d and brow n. D i s t i n c ti v e arom a and f l a v o r l o s t C o lo r fad ed and d ark en ed C o lo r fad ed and no d a rk e n in g 943 • ......................... D is t i n c ti v e c o l o r , f la v o r and arom a l o s t C o lo r f a d e d . D i s t i n c t i v e f la v o r s t i l l p r e s e n t • 4 TABL2 B SPIHACH B, DRIED 1 .3 5 HOURS AT 140° F . ; C, 1 .5 HOURS AT 1 .4 0 ° P . ; D, 3 .5 HOURS AT 1 4 0 ° F . Days S to ra g e B 8 .9 0 p e r c e n t w a te r C 5 .3 8 p e r o e n t w a te r D 3.81 p e r c e n t w a te r 103 F la v o r poor l i k e hay C o lo r s l i g h t l y f a d e d . F la v o r f a i r C o lo r unch anged f la v o r f a i r 778 C o lo r s l i g h t l y brow ned. F la v o r p o o r l i k e hay Same a s p r e v io u s ex am i- n a t io n . C olor v e ry s l i g h t l y f a d e d . F la v o r f a i r . I n com m ercial d e h y d ra tio n th e v e g e ta b le s a r e u s u a lly i n p rim e c o n d itio n when ta k e n to th e d e h y d ra tio n p la n t* They a r e w ashed th o ro u g h ly an d th e n s l i c e d , th e d e g re e o f f i n e s s depending on th e p a r t i c u l a r v e g e ta b le . They a r e th e n s p re a d on t r a y s to go to th e d e h y d ra tin g f l u e s . E k ro th 1 p r e f e r s th e m e c h an ical d r a f t to th e n a t u r a l f l u e d r a f t . H eated a i r a f t e r p a s s in g once o v e r th e p ro d u c t to be d r ie d i s o n ly p a r t l y s a tu r a t e d w ith v a p o r and can b e u se d o v e r a g a in , p ro v id e d m e ch an ical d r a f t i s em ployed. M o ist a i r i s a b e t t e r d ry in g medium th a n h o t, dry a i r , a s i t does n o t c lo s e th e p o re s o f th e o u te r l a y e r o f th e p ro d u c ts b e f o r e m o is tu re h a s been ta k e n from th e i n t e r i o r . Some v e g e ta b le s r e q u ir e " b la n c h in g " o r " p r o c e s s in g ," w ith h o t w a te r o r steam and som etim es s a l t and so d a s o lu t io n , b e fo re d e h y d ra tio n , w as shown by N ic k o ls an d G ro s s * . I t was fo u n d t h a t t h i s m ethod w ould c a u s e th e p ro d u c t t o r e t a i n i t s c o lo r an d f l a v o r . The " b la n c h in g " o r " p ro c e s s in g " v i r t u a l l y am ounted to p rec o o k in g b e f o r e d r y in g . The p e r io d of p r o c e s s in g s h o u ld b e of such le n g th and i n t e n s i t y t h a t th e m a te r ia l s a r e te n d e r and h e a te d th ro u g h , b u t n o t so s o fte n e d a s t o c o l la p s e and lo s e t h e i r shape when sp re a d on t r a y s . 1 C . V . E k ro th , oj>. c i t . 2 P . F . N ic k o ls and 0 . R . G ro ss, C hem ical Age (New Y ork: 1 9 3 1 ), V o l. 39, p p . 1 3 9 -4 1 . 6 1 Owen shows i n h i s p a t e n ts how h e a te d a i r of r e l a t i v e l y low h u m id ity i s p a s s e d th ro u g h th e m ass o f v e g e ta b le s and th e te m p e ra tu re , p r e s s u r e and r a t e o f flo w o f th e a i r so c o o rd in a te d w ith th e mass o f m a te r ia l t h a t ex o th erm ic r e a c t i o n s w i l l ta k e p la c e in th e m a t e r i a l . T h is f u r n is h e s p a r t o f th e l a t e n t h e a t o f v a p o r iz a tio n , n e c e s s a r y f o r th e d ry in g , an d so th a t th e t o t a l h e a t a v a ila b le w i l l s u f f i c e to p re v e n t con d e n s a tio n w ith in th e v e g e ta b l e s . The work o f F a lk , F ra n k e l and McKee 2 seems to show vacuum d e h y d ra tio n i s b e t t e r b e c a u se s u b -a tm o sp h e ric steam c o u ld le a v e from a l l p a r t s o f th e p ro d u c ts a t low te m p er a t u r e s . T h is i s n o t p o s s ib le w ith th e h o t a i r b l a s t d eh y d - r a t e r s . T h is m ethod i s l e s s e x p e n siv e a l s o b ecau se of l e s s h e a t b e in g n e c e s s a ry and a s h o r t e r tim e to do th e same w o rk . In t h e i r work th e ap p e a ra n c e o f th e p ro d u c ts was s a t i s f a c t o r y in e v e ry c a s e . The m o is tu re c o n te n t v a r ie d from 5 to 30 p e r c e n t depen d in g upon th e le n g th o f tim e of d e h y d r a tio n . In g e n e r a l, vacuum d e h y d ra tio n cau sed c o n s id e r a b ly l e s s d i s - t r u c t i o n o f enzyme a c tio n th a n d id th e a i r - b l a s t d e h y d r a tio n . The low te m p e ra tu re was h e lp f u l i n p r e v e n t i i g th e v o l i t a l i z - 1 B. J . Owen, TJ. S . P a t ., 1 ,7 8 1 ,4 7 3 , 1 9 3 1 . 2 K. G eorge F a lk , 3 . M. F ra n k e l and R. H. McKee, I n d . 3 n g . Chem., V o l. 1 1 , p p . 1 0 3 6 -7 , 1 9 1 9 . 7 a t io n o f th e e s s e n t i a l o i l s so t h a t on r e - h y d r a tio n th e f r u i t s had t h e i r o r i g i n a l f l a v o r s . T here seem ed t o be v e ry l i t t l e o x id a tio n i n t h i s p r o c e s s . H a rris o n 1 t r e a t e d s l i c e d f r u i t s an d v e g e ta b le s w ith a s o lu tio n of sodium c h lo r id e o r p h o sp h o ric a c id ° to p re v e n t o x id a tio n and th e n d r ie d i n c a rb o n d io x id e , n itr o g e n o r any i n e r t , n o n -o x id iz in g g a s . T h is te n d s to p r e s e rv e v ita m in s , how ever, m ost v ita m in s w i l l b e r e ta in e d i f th e te m p e ra tu re i s k e p t below 65° C. a s th a t i s th e ap p ro x im a te te m p e ra tu re a t w hich v ita m in C o x id iz e s . S u lf u r d io x id e 3 a l s o c a u s e s r e t e n t i o n o f v ita m in C a s w e ll a s t o p re v e n t d a rk e n in g due to enzym ic a c t i o n . T here a l s o seem s to be a n a d v a n ta g e to th e s u l f u r d io x id e p r e c e s s i n t h a t i t p re v e n ts s p o ila g e by m icro o rg an ism s an d h a s te n s d e h y d ra tio n by p la sm o ly z in g th e c e l l s and a llo w in g th e m o is tu re to e s c a p e more r e a d i l y . B. EXPERIMENTAL PR0CE2DUR2 AND RESULTS The f i r s t m ethod p e rs u e d in th e i n v e s t i g a t i o n r e p o r te d i n t h i s t h e s i s was o f th e a i r b l a s t ty p e . The d e h y d r a te r c o n s is te d of a wooden box h o ld in g tw en ty t r a y s 17 b y 18 1 B . S . H a rris o n , U. S . P a t,., 1 ,3 8 7 ,8 1 0 , 1 9 3 1 . 3 B rin c h and S p eh r, F ren ch P a t .. 6 9 6 ,1 9 0 , 1 9 3 0 . 3 P . F . N ic h o ls and A. W. C h r i s t i e , C a l. A g r i. E xp. S ta ti o n . B u i., 4 8 5 , p p . 1 -4 6 , 1930 8 in c h e s . At one end o f th e box e l e c t r i c h e a tin g e le m e n ts w ere f ix e d i n a 15 in c h p ip e th ro u g h w hich a i r was fo rc e d by m eans o f an e l e c t r i c f a n . The a i r p a sse d o v e r th e t r a y s and on o u t a t th e o th e r end o f th e d e h y d r a te r . O th er a p p a ra tu s c o n s is te d o f a m e c h a n ic a l s l i o e r and many w ashing pans* The p ro c e e d u re fo llo w e d was r a t h e r s im i l a r f o r a l l p r o d u c ts . A f te r a th o ro u g h w ash in g , th e p ro d u c ts w ere s l i c e d w h ile w et, w ere p la c e d upon t r a y s , and th e n w ere p la c e d i n t o th e d e h y d r a te r . Sam ples w ere w eighed a t d i f f e r e n t i n t e r v a l s of tim e an d th e r e s u l t s a r e shown i n g r a p h s . The te m p e ra tu re c o u ld be r e g u la te d by c u t t i n g o u t some o f th e h e a tin g e le m e n ts i f n e c e s s a r y , u s u a lly a te m p e ra tu re o f 5 5 -6 0 ° C. was m a in ta in e d . The m a te r ia l s w ere a l l k e p t in th e d e h y d ra te r u n t i l th e y n e a r ly a t t a i n e d a c o n s ta n t w e ig h t. The tim e d ep en d in g upon th e n a tu r e o f p r o d u c t, th e th ic k n e s s o f s l i c e s , th e flo w o f a i r , th e te m p e ra tu re , and th e amount upon each t r a y . The p ro d u c ts de h y d ra te d w ere: c e le r y , l e t t u c e , s p in a c h , c a r r o t s , to m a to e s, o ra n g e s , and f o r c e r t a i n e x p e rim a n ta l p u rp o s e s , d a h l ia t u b e r s . The d a h lia s w ere t e s t e d t o f in d th e h ig h e s t w a te r con t e n t a t w hich th e y w ould keep s a t i s f a c t o r i l y . Sam ples w ere ta k e n from th e t r a y s a t th e en d o f tw o, f o u r , s ix , e i g h t , and te n h o u r s . The f i r s t two sam p les s p o ile d v e ry soon w h ile th e l a s t t h r e e , w hich w ere a l l u n d e r 5 .3 p e r c e n t w a te r c o n te n t, were i n v e ry good c o n d itio n a t th e end o f a y e a rs tim e . The l e a f y v e g e ta b le s such a s : s p in a c h , l e t t u c e , and Hot Air D e h / d r a t e r / 8 " N “T l Th e r mometers & 4 T ■ ........................... - .. 7 1 * I \ \ i 1 \ / ,"A V I / / \ \ ~ ... Wir eTra.y s \ A « ' \ .V T -fan Seating Elements fxusi4 e of f>»>ej F t j . /V *. i CO 10 c e le r y were th e e a s i e r t o d e h y d r a te . N ext i n o r d e r a r e th e r o o ts and t r b e r s , d a h l ia s and c a r r o t s , w hich d e h y d ra te d v e ry r a p id ly i f s l i c e d a b o u t 3 /1 6 " t h i c k . The f r u i t s , to m a to e s an d o ra n g e s w ere somewhat more d i f f i c u l t t o d e h y d ra te b e c a u se o f s u g a rs and o i l s p r e s e n t . A slow p r e - h e a t was found to be ad v a n tag e o u s h e r e to p re v e n t s e a lin g o f th e o u te r c e l l s . A ll o f th e p ro d u c ts w ere v e ry h y d ro s c o p ic and h ad to be k e p t in a i r t i g h t c o n t a i n e r s . They a l l r e ta in e d t h e i r c o lo r and upon r e - h y d r a tio n th e t a s t e an d o d o r was s im ila r to th e f r e s h p r o d u c ts . Some w ork was done in r e d u c tio n d e h y d r a tio n . T h is a p p a ra tu s c o n s is te d o f an e ig h t in c h t i l e (page 1 1 ) b e in g p la c e d i n an u p r ig h t p o s i t i o n . T ray s w ere su spended from th e to p an d th e o n ly medium p a s s in g th ro u g h th e a p p a ra tu s was th e red u ced g a s e s com ing from a g a s b u rn e r b e lo w . T h is p ro c e s s was d e f i c i e n t o n ly i n t h a t c o n v e c tio n c u r r e n t s w ere n o t s tro n g enough t o p ro d u ce am ple c i r c u l a t i o n . Had m e ch an ical c i r c u l a t i o n b een p ro v id e d th e p ro c e s s w ould have b ee n much more e f f i c i e n t . The p ro d u c ts how ever w ere o f a v e r y good c o lo r and odor l i k e l y due to th e u n - o x id iz in g medium i n w hich th e y w ere d e h y d ra te d by t h i s p r o c e s s . The fo llo w in g g ra p h s h av e a s o r d i n a t e s , w e ig h t o f th e p ro d u c t i n gram s, p l o t t e d a g a in s t th e tim e i n h o u rs , a s ab s c i s s a s . In each c a s e a v e ry good d e h y d ra tio n cu rv e was ob t a i n e d . 11 8 -»i 35 V —-------- ar 6 ' L '—L \ F * a u s t Wood S Up fo r t . 8" Ti I e \ V / / w i r e T r a / s A s h e $to $ B u f f e r -Bunsen B urn tr Asb e stos A ir In-t&k e G *as “ - ” Stone B a.8 e F 19 . R e d u c t i o n D e k / d r d t e r (C r*s $e cti °n ) 1 3 « i > m t? - - «d c < ■ w 0 1 > • o o $- f - a Cfl *# £ X J L J *c f , »• T o «t* ... i « ■ <o •K J f“ . . . ^ • M l ■ . O X a Z • * « ► > • C M W < i 1 > > < < P i K < < • > > ) 1 « « ► ► < < • > > « ( > ■ - & \ U T 2 jl b D (n 21 t i < > n C u r v e to r-i • $ Ji n < 5 N (( i 1 • ! \ J * ► • t i 4 t i r o > 1 { 0 T f" / ■ i I j A A > V i < v * O' p > ACT 3f < * » wj # I J oO ! ? » 0 VH j . 9 1 1 M / N 1 # W 'V 1 c A J * : u °? J t a p / a Hi C i DEHYDRATIOH OF DAHLIAS 16 TABLE 2 L TABLE I I N et gram s d a h l ia s T o ta l h o u r 8 N et gram s d a h lia s T o ta l h o u r s 500 0 :0 0 500 0 :0 0 446 0 :3 0 454 0 :3 5 385 1 :0 0 404 1 :o o 355 1 :30 355 1:30 365 3 :4 0 304 3 :1 5 198 3 :3 0 343 3 :0 0 175 4 :3 7 301 4 :0 0 143 5 :3 7 157 5 :0 0 133 6 :3 0 135 6 :0 0 117 7 :3 0 131 7 :0 0 110 8 :3 0 115 8 :00 108 9 :3 0 113 9 :1 5 107 1 1 :05 111 1 1 :1 5 107 1 3 :5 0 111 1 3 :1 5 DEHYDRATION OF CELERY DEHYDRATION OF LETTUCE TABLE I I I TABLE IV N et gram s T o ta l Net gram s T o ta l c e le r y h o u rs l e t t u c e h o u rs 350 0 soo 350 0 :0 0 181 0 :3 0 193 0 :3 0 111 1 :0 0 135 1 :00 67 3 :3 0 97 1 :3 0 33 3 :3 0 45 3 :3 0 17 4 :3 0 36 3 :3 0 15 5 :3 0 16 4 :30 14 6 :3 0 13 5 :3 0 14 7 :3 0 13 6 :3 0 14 8 :3 0 13 7 :3 0 17 VP O I B . u> w U rtJ "X J h - >■% o 19 DEHYDRATION OF CARROTS DEHYDRATION OF TOMATOES TABLE V _ TABLE VI Net grams c a r r o t s T o tal h o u rs Net grams tom atoes T o ta l h o u rs 350 0 :0 0 350 o :oo 300 0 :3 0 333L o :so 164 1 :0 0 304 1 :0 0 143 1 :3 0 188 1 :3 0 117 3 tOO 167 3 :00 97 3:30 151 3 :3 0 79 3? 30 132 3:30 50 4 :3 0 97 4 :3 0 40 5:30 76 5 :30 36 6:30 63 6:30 34 7:30 48 7:30 31 8:30 43 8 :3 0 31 10:30 36 l i : 30 31 13:30 34 1 3 :30 31 14:30 30 15:30 31 16:30 37 1 7:30 30 3 1 DEHYDRATION OF ORANGES TABLE VII Net grams oran g es T o tal h o u rs 350 0 :00 185 1 :0 0 171 lr 3 0 156 3:00 145 3:30 135 3:30 131 4 :3 0 107 5:30 99 6:30 93 7:30 87 8:30 76 10:30 73 1 3 :30 67 14:30 66 16:30 SU M M A RY OF DEHYDRATION RESULTS TABLE C P roduct Hours tim e Temp, o C. io w a te r i n f r e s h i w ate r in d e h y d rated w ate r removed D ah lias 1 3 .3 60 7 9 .3 3.35 99.5 C elery 7 .5 60 9 4 .5 1 .8 0 99.8 L e ttu c e 7 .5 60 94.7 4 .3 0 99.7 C a rro t s 1 4 .5 55 8 8 .3 4.84 97.5 Tomatoes 1 5 .5 55 94.3 7.00 96.1 Oranges 1 6 .5 55 78.1 15.38 95.1 S pinach 9 .0 55 9 3 .3 3.83 99.5 3 3 0 . PULVERIZATION The d e h y d ra te d sp in a ch was p la c e d in a b a l l m i l l , ap p ro x im a te ly one pound a t a tim e , and allo w ed t o r o t a t e a t the r a te o f ab o u t one r e v o lu tio n p e r second f o r two h o u r s . The ch arg e was th e n removed to an a i r t i g h t c o n ta in e r a s soon a s p o s s i b le , and a new ch arg e o f sp in ach was p u t i n t o th e m i l l . As soon a s th e sp in a c h was s u f f i c i e n t l y p u lv e riz e d th e m ill was c le a n e d thouroughly. w ith d i s t i l l e d w a te r and allo w ed to d r y . T his same p ro c e e d u re was fo llo w ed i n th e p u l v e r i z a t io n of th e o th e r d eh y d rated p ro d u c ts , nam ely: l e t t u c e , c e le r y , c a r r o t s , to m ato es, and o ra n g e s . There was o f te n c o n s id e r a b le d i f f i c u l t y in removing th e d i f f e r e n t powders from th e b a l l m il l, due to th e f a c t th a t th e s e p ro d u c ts were v ery h y d ro sc o p ic and would soon r e h y d ra te th em selv es t o th e p o in t where th e y would become v ery s t i c k y . S ince th e r e was alw ays a few stem s and f o r e ig n mat e r i a l s i n th e powder a f t e r i t came from th e b a l l m i l l , i t was n e c e s s a ry t o g rad e th e m a c e ra te d p r o d u c ts . T his was accomp l i s h e d by s e iv in g , a s m a ll sam ple a t a tim e , th ro u g h a 1 0 0 - mesh, s c r e e n . T his o p e r a tio n a l s o had t o be done a s r a p id ly a s p o s s i b le to p r e v e n t r e h y d r a tio n . A f te r t h i s p ro c e e d u re was co m p leted th e sam ples were b o t t l e d i n a i r t i g h t c o n ta in e r s f o r f u tu r e o b s e r v a tio n and s tu d y . CHAPTER I I A STUDY OF DEHYDRATED VEGETABLES In stu d y in g th e p r o p e r t i e s of d e h y d ra te d v e g e ta b le s i t was n o te d t h a t th e r e was a tendency f o r them to n e u t r a l iz e a c id s , a lth o u g h th e y showed no b a s ic r e a c t i o n tw oard l i t m u s . The re a s o n a b le th e o ry f o r t h i s a c t i o n i s , t h a t th e s a l t s o f th e weak a c id s l i b e r a t e d £rom th e v e g e ta b le s showed “b u f f e r 1 1 a c tio n in such c a s e s . Thus i t i s th e o b je c t o f t h i s c h a p te r t o rev iew , t o a c e r t a i n e x te n t, b u f f e r s and t h e i r b e h a v io r A. THEORY OF BUFFERS As f a r back a s 1900 Fernbach and H u b e rt,^ in th e co u rse of some work on th e d i a s t a t i c a c t i v i t y of m a lt, o b se rv e d t h a t p a r t l y n e u t r a l i z e d s o lu t io n s o f p h o sp h o ric a c id tended to r e s i s t changes in h y d ro g e n -io n c o n c e n t r a t i o n ,2 and th ey compared t h i s r e s i s t a n c e to t h a t e x e rte d by "un tam p o n ,“ 3 meaning "plug" o r "bung". The word was ad o p te d by S orsensen ^ Huber T. S. B r itt o n , Hydrogen Io n s (Hew’ York: D. Van H o stran d C o., 1939), p . 1 3 2 . 2 Donald D. Van S ly k e, The J o r . of B i o . Chem. ( B a l ti m ore: 1 9 3 3 ), V o l. 53, p p . 5 5 4 -5 . 3 J u l i u s G ra n t, The Measurement of Hydrogen Ion Con c e n t r a t i o n (Hew York: Longmans, Green and C o .), p . 1 9 . 24 i n 1909 and was t r a n s l a t e d by him i n t o German a s " p u f f e r , " * th u s we g e t th e term " b u f f e r ." T h is p ro p e r ty o f c e r t a i n s o l — u tio n s o f r e s i s t i n g change in hydrogen io n c o n c e n tr a tio n , on a d d i t i o n o f a c id o r a l k a l i , i s known a s " b u f fe r a c t i o n , " and th e s o lu t io n s a r e c a l l e d b u f f e r " s o l u t i o n s ." ^ B u ffe r s u b s ta n c e s a r e s a l t s o f weak a c id s o r b a s e s , or 3 m ix tu re s o f weak a c id s o r b a s e s w ith t h e i r s a l t s . Weak a c id s a re weak f o r th e re a so n t h a t th e y a r e s l i g h t l y io n iz e d . I f a s a l t o f th a t a c id i s added th e n th e a n io n s o f th e s a l t w ill s t i l l f u t h e r r e p r e s s th e io n iz a t io n o f th e a c id , though th e s a l t may be g r e a t l y i o n iz e d . The same r e a c tio n ta k e s p la c e betw een weak b a s e s and t h e i r s a l t s . Through th e s e k in d of r e a c t i o n s , we th e n may c o n tr o l th e number o f f r e e h y d rio n s or a n io n s in a b iv e n chem ical r e a c t i o n by th e use of th e s e " r e g u la to r m ix tu r e s ." 4 pH = log(H ^) we a r e r e a l l y c o n t r o l l i n g th e pH v a lu e o f th e s e s o lu t io n s by b u f f e r s • They a r e o f v e ry g r e a t v a lu e to th e a n a ly s t and 1 M a n sfield W. C la rk , The D e te rm in a tio n of Hydrogen Io n s (B a ltim o re : W illiam s and W ilk in s Co., 192877 p . 50. ^ F re d e ric k H. Getman, O u tlin e s of T h e o re tic a l C hem istry (Hew York: John W iley and Sons, 1928}, p . 571. 3 J u l i u s G ra n t, o n . c i t .. p . 19. 4 W. M a n sfield C lark , o n . c i t .. p . 50 25 p h y s io lo g ic a l ch em ist i n t h a t th ey f u r n is h a means of s t a b i l i z in g th e hydrogen io n c o n c e n tr a tio n w ith in a p re d e te rm in e d zone* These b u f f e r system s a l s o a c t a s r e s e r v o i r s o f a l k a l i f o r th e n e u t r a l i z a t i o n of a c id e n d -p ro d u c ts o f m e tab o lism . ^ I n p l o t t i n g pH v a lu e s a g a in s t added a c id o r a l k a l i th e r a t h e r common t i t r a t i o n cu rv e i s th e r e s u l t . The S -shaped cu rv e i s c h a r a c t e r i s t i c of b u f f e r a c id s o r a l k a l i s , and d e m o n stra te s th a t in th e m iddle p o r tio n of th e cu rv e where h a l f of th e a c id i s n e u t r a l i z e d ( r a t i o o f s a l t t o a c id i s eq u al to u n ity ) th e r a t e o f change of pH i s th e l e a s t . ^ A one p e r c e n t s o lu t io n of W itte p eptone was found t o have a pH v a lu e o f 6 .8 7 . To eq u al p o r tio n s of th e s o lu tio n were added s u c e s s iv e ly in c re a s in g am ounts of N/10 l a c t i c a c id and th e r e s u l t i n g pH was m easured i n each c a s e . There was a ls o added t o eq u al p o r tio n s of th e s o lu tio n s u c e s s iv e ly in c r e a s ing am ounts of N/lO NaOH and th e r e s u l t i n g pH m easured a s b e f o r e . I f th e pH v a lu e s were p l o t t e d a s o r d in a te s and amount of a c id o r a l k a l i added i n each c a s e a s a b s c i s s a s , a d i s t i n c t S -shaped b u f f e r curve would r e s u l t . 3 I f th e same th in g were done u s e in g a f iv e p e r cent s o lu t io n of W itte 1 P h i l i p B. Hawk and O laf Bergeim , P r a c t . P h v so . Chem. ( P h ila d e lp h ia : P . B la k is to n * s and Son, 1937)", p . 4 2 0 . 3 L oo. c i t . 3 w. M a n sfie ld C la rk , o n . c i t .. p . 51. H t ra tio 37 p e p to n e , a much f l a t t e r cu rv e would r e s u l t d is p la y in g more b u f f e r a c t i o n . Then i f a t h i r d curve sh o u ld be p l o t t e d add ing th e a l k a l i to a d i l u t e a c i d - d i s t i l l e d w a te r s o lu t io n , th e cu rv e would be v e ry much s te e p e r showing p r a c t i c a l l y no b u f f e r a c tio n b e in g d is p la y e d by th e w a te r (see page 3C 6 ) . The b u f f e r a c t i o n t h e r e f o r e must be dependent upon th e k in d , and a l s o th e c o n c e n tr a tio n of th e c o n s t i t u e n t s p r e s e n t . I f we have th e weak a c id HA i t w i l l re a c h e q u i l i b - erium i n th e s o lu t io n ac c o rd in g to th e law o f mass a c t i o n HA ^ H+ + A* (1) The speed t o th e r i g h t b ein g eq u al to k^ and to th e l e f t i s k 2 . S in ce th e r a t i o of a c o n s ta n t to a c o n s ta n t i s a n o th e r c o n s ta n t we have (A*) * (H+) _ kx _ (HA) ; k a = K (2) 3 L et (s)' equal c o n c e n tr a tio n o f t o t a l m a te r ia l when s a l t s of a c id a r e p r e s e n t i n a m ix tu re o f b o th th e n (S) * (A*) ♦ (HA); + ( s ) . (3) I n t h i s fo rm u la (s ) r e p r e s e n ts sum of c o n c e n tr a tio n o f un d i s s o c i a t e d s a l t s . In most c a s e s however, i t seems t h a t th e s a l t s form ed a r e so n e a rly c o m p le te ly io n is e d th a t we may assume (s ) to be n e g l i g i b l e . Then from th e two e q u a tio n s above (3) and (3) we may o b ta in (4) (A*) % (S) J K a ♦ (HA) (4 ) = 38 The r a t i o ( * ) /( S ) r e p r e s e n ts th e f r a c t i o n d i s s o c i a t e d . This r a t i o i s o fte n g iv e n th e symbol . P e rc e n ta g e d i s s o c i a t i o n th e n g ein g eq u a l to 100 < x . The l a s t e q u a tio n may be w r i t t e n t <* = L - r - (5) : Ka ♦ (H*) I S o lv in g t h i s e q u a tio n f o r (H"^) we g e t 1 - c X (H*) a K ----------------------------------------------- (6) < x Taking th e lo g r ith m of th e r e c i p r o c a l o f each sid e o f (6) we o b ta i n 1 1 * Log -------- a lOg — lOg (7) (H*) , K a 1 - < * S ince lo g l / ( H ‘ 1 ‘) s pH lik e w is e lo g 1/K^ S pKa th e r e f o r e we * " may w rite pH = • » ■ lo g —i (8) . 1 - < * v The b e s t u n i t t o e x p re s s b u f f e r v a lu e i s th e d i f f e r e n t i a l r a t i o dB /d(pH ),^ e x p re s sin g th e r e l a t i o n s h i p betw een th e in c re m en t ( in gram e q u iv a le n ts p e r l i t e r ) o f stro n g b ase B added to a b u f f e r s o lu tio n and th e r e s u l t a n t increm ent i n pH. Thus th e in crem en t o f a stro n g a c id i s th e n e g a tiv e e q u i v a l- 1 Donald D. Van S lyke, ojo. c i t .. p . 528. 29 e n t, o r -d B . In th e s e term s a s o lu tio n h a s a b u f f e r v a lu e o f one when a l i t e r w i l l ta k e up one gram e q u iv a le n t o f s tro n g a c id o r a l k a l i p e r u n i t change in pH* ^ I f base i s added to a s o lu t io n , pH i s in c r e a s e d , so t h a t b o th dB and d(pH) a r e p o s i t i v e . I f a c id i s added b o th dB and d(pH) a re n e g a tiv e . The r a t i o dB/d(pHO i s , th e r e f o r e , alw ays a p o s i t iv e n u m e ric a l v a l u e . Going ahead w ith th e m a th em atic al d e r iv a tio n of th e d i f f e r e n t i a l r a t i o dB/d(pH) we may r e w r i te (8) w ith th e 2 n a t u r a l lo g rith m pH a pKo - ► 0 .4 3 4 3 I n — ----- (9) . 1 - ta k in g th e f i r s t d e r iv a tiv e we g e t 1 - < * d(pH) = 0 .4343 — d (-----------) (10) 1 - < * th e d e r iv a tiv e of w ith r e s p e c t t o pH i s d = 3 .3 0 3 (1 -<*) *• (11) d(pH) : TOien th e amount of b u f f e r a c id in th e s o lu tio n e q u a ls th e amount o f b u f f e r s a l t w ill be eq u al to 0 . 5 . S o lving ( l l ) we fifid* d*/d(pH ) » 2.303(1 - 0 .5 ) 0 .5 = 0 .5 7 8 , which i s th e maximum v a lu e o b ta in e d by a u n iv a le n t a c i d . D isre g a rd in g 1 Donald D. Van S ly k e, op.. c i t .. p . 528. % W. M a n sfie ld C lark , o n . c i t .. p p . 55-7 30 (s) a s b e f o re we may w r ite Base added (B) 1 o< = ------------------ = and d * = — d(B) (13) : T o ta l a c id : (S) ; (s) S o lving (12) f o r d(B) and d iv id in g by (10) we o b ta in (13) d(B )/d(pH ) = 2 .3 0 3 * (1 - * ) ( S ) (13) S u b s titu t in g th e v alu e of c < i n (5) i n to e q u a tio n (13) we o b t a i n th e tr u e v a lu e o f th e r a t i o d ( B ) i , K. (H*) # x - — 2 .3 0 3 (S) ------ —---------- 5- (14) d(pH) , (Ka (Hr ) ) which i s o f te n r e f e r r e d to a s / 3 . ^ I f a s tro n g b ase i s added to w a te r we may assume th a t th e b ase i s co m p letely d i s s o c i a t e d . Then d(B) = d(0H*) and d(B) d(0H») (OH*) _ - --------------------- =------------= 2 .3 0 3 (H*) (15) d(pH) . d lo g (0H») 0 .4 3 4 3 • For th e same re a so n in c a se o f a stro n g a c id added t o w a te r we would have d(B )/d(pH ) s 2 .3 0 3 (H*) (16) The b u f f e r e f f e c t i n stro n g a c id o r a l k a l i n e s o lu tio n s i s th e sum of th e s e two e f f e c t s , 2 /3 s d(B )/d(pH ) = 3 . 303( (H *4 *) f (0H +)). (17) I f th e v a lu e s of /3 a r e p l o t t e d a s o r d in a te s a g a in s t 1 Donald D. Van S lyke, lo o , c i t . 2 W. M a n sfie ld C lark , o n . c i t .. p . 56, 31 th e c o rre sp o n d in g pH v a lu e s a s a b s c is s a s , a cu rv e w i l l r e s u l t (page 33) from which th e b u f f e r v a lu e of a m ix tu re may be r e a d i l y d eterm in ed f o r any g iv e n pH. I t i s p o s s ib le t o make a v e ry a c c u r a te a p p ro x im a tio n o f th e v a lu e s o f / 3 by the* fo llo w in g m ethod: p l o t pH v a lu e s a s a b s c is s a s , and p l o t a s o r d in a te s , /3 i n gram e q u iv a le n ts o f b ase added p e r l i t e r . Then i n p la c e of dB and dpH, i n f i n i t e s i m a l in c re m e n ts , we may u se m easurable in c re m e n ts a B and a pH. The o n ly d if f e r e n c e i s t h a t dB/dpH w ill o b ta in th e e x c a t slo p e of th e ta n g e n t to th e t i t r a t i o n cu rv e f o r a l l v a lu e s o f pH, w h ile 2iB/apH o b ta in s th e slo p e f o r th e mean v a lu e o f pH. 1 I f th e in c re m e n ts a r e ta k e n sm all enough v a lu e s of /3 a r e s u f f i c i e n t l y a c c u r a te f o r n e a r l y a l l p u rp o s e s . There a r e many s u b s ta n c e s th a t can cause b u f f e r a c tio n th e m ost im p o rta n t a r e a c e t a t e s , b o r a te s , c i t r a t e s , phos p h a te s , and p h t h a l a t e s . In c a se th e r e i s a s o l i d phase d i s p e rs e d in th e r e a c t i n g m ix tu re , th e s e p a r t i c l e s may ad so rb some component o f th e a c id -b a s e e q u ilib r iu m . Henderson c a l l ed a t t e n t i o n t o t h i s w h ile Bovie and o th e r s have shown th e 2 b u f f e r in g e f f e c t o f c h a r c o a l. A number of b u f f e r s occur i n n a tu r e in th e form of complex o rg an ic compounds, w h ile a m in o -a c id s, p e p to n e s, b e e f b r o th , m alt e x t r a c t , g e l a t i n e , 1 Donald D. Van S lyke, o p . c i t .. p . 53. ^ W. M a n sfie ld C la rk , o p . c i t . , p . 530. : cur ve N o. : ; < f ; 1 ; - ■ A l « 1 # -'3 c /ue t< f H * J ctie ' !o t« < » J -* / A f A f \ "/3« f 0 - Z M - ace tic ac 4 • 1 .w i 9 - 4 - t % wp A |ll -+ -/J 4 *• ac et i c a :k4 .w* A r t 9 *99i ( 4 ; » ^ \ * k > ' < 1 i i 1 1 i 0 X t l 2 23 p H-i » w ae S < 3 i f t S >#- an /•** M 1 ,xti l r c > 5 \ ^ ce tic A < id ■ ■ j a/ 4 Ac e t a 1 : e w C O 33 e t c . , have s i m i l a r p r o p e r t i e s .^ These s u b s ta n c e s a r e u s u a l l y a m p h o te ric , and may a c t a s a b a se i n a c id s o lu t io n s or a s an a c i d in a l k a l i n e s o l u t i o n s . Hence t h e i r c a p a c ity o f r e moving h y d rio n s and a n io n s , and th e re b y o f r e s i s t i n g a change i n pH. T h e ir mode of i o n i z a t i o n may be e x p re sse d th u s : HT * ROH ^ HROH ^ R H *- OH*. 3 (A c id ic ) (B asic) The o rg a n ic am pholytes a r e of g r e a t im portance in b io lo g y . A m ino-aeids, which c o n ta in b o th a c id ic (-COOH) and b a s ic (-HHg) g ro u p s, a r e an exam ple. B. EXPERIMENTAL W O RK OH THE BUFFER ACTIOH OF DEHYDRATED Y2BSTABLES l a . C o lo rim e tric T i t r a t i o n . The d i r e c t t i t r a t i o n of a w a te r s o lu t io n of th e v e g e ta b le p ro d u c ts , by means of in d i c a t o r s , was im p o s sib le due t o th e c o lo r of th e v e g e ta b le i t s e l f . In o rd e r t o over come t h i s e f f e c t th e fo llo w in g p ro c e e d u re was p u rsu e d . A th r e e gram sample of th e sp in a ch powder was made up w ith 50 c c . of d i s t i l l e d w ate r and s t i r r e d f o r two m in u te s . At t h i s tim e 10 p e r c e n t, a l k a li n e f r e e , h ig h flo w su p er c e l l was added t o a i d in f i l t e r i n g . The m ix tu re was f i l t e r e d by means of s u c tio n . Due t o th e c o l l o i d a l n a tu r e o f th e m ix tu re , f i l t e r i n g was p r a c t i c a l l y im p o s s ib le * J u l i u s G ra n t, ego. c i t . . , p p . 1 9 -3 1 . 2 L oo. c i t . 34 w ith o u t th e su p er c e l l . The r e s id u e was washed w ith a meger amount o f d i s t i l l e d w a te r and th e combined f i l t r a t e s re c o v e re d . To th e f i l t r a t e was added 0 .6 gram o r 10 p e r c e n t n o r i t , which a l s o was n e u t r a l to a c id by p re v io u s e x a m in a tio n . The n o r i t ad so rb e d a la r g e m a jo r ity o f th e g reen c o lo r in g m a tte r i n th e s o l u t i o n and a f t e r a second f i l t e r i n g , th e f i l t r a t e was a f a i r l y c l e a r w a te r e x t r a c t o f th e sp in a c h sam p le. The f i l t r a t e was made up to 200 c c . w ith d i s t i l l e s w a te r, and t i t r a t e d w ith 0 .5 2 3 2 N. h y d r o c h lo ric a c id u se in g m ethyl orange a s an i n d i c a t o r . The r e s u l t s o b ta in e d a re shown i n th e 'f o llo w in g t a b l e : TABLE D COLORIMETRIC TITRATIOH RESULTS OB DEHYDRATED VEGETABLES Grams Spinach c c . 0 .5 2 3 2 H. HC1 3 3 .2 3 3 3.28 3 3.33 2 b . E le c tr o m e tr ic T i t r a t i o n . S in ce th e d e c o lo r iz a tio n p ro c e s s removed th e c h lo r p h y ll and p ro b ab ly o th e r o rg a n ic m a tte r, th e o rd in a ry t i t r a t i o n method does n o t g iv e a tr u e 35 v a lu e of a c id n e u t r a l i z i n g povrer a s i t e x i s t s in th e a c tu a l v e g e ta b le s o l u t i o n ; a n o th e r means was th e n t o be fo u n d . The e l e c t r o m e tr ic method seemed t o be th e o nly way th a t would g iv e d e f i n i t e r e s u l t s . The quinhydrone method i s o nly a c c u r a t e up t o pH 8 . T h e re fo re s in c e a l a r g e r pH range was d e s ir e d , to t e s t a l s o f o r b u f f e r a c tio n a g a in s t b a s e s , th e hydrogen e le c tr o d e method was s e l e c t e d . A s tu d e n t p o te n tio m e te r was assem bled and s ta n d a r d iz e d . The calom el h a l f c e l l , u se in g a s a t u r a t e d KC1 b rid g e , was u se d a g a in s t th e hydrogen e l e c t r o d e . A m ech an ical s t i r r e r was i n s t a l l e d t o in s u r e c o n s ta n t a g i t a t i o n . The te m p e ra tu re co u ld be c o n t r o ll e d by a w a te r b a th o r bunsen b u rn e r, and d e term in ed by a therm om eter whi ch was suspended i n th e s o lu tio n a t a l l tim e s . The a c id o r a l k a l i c o u ld be added by means of a b u r e t t e to which a d ro p p e r was a t ta c h e d . In a l l c a s e s hy d ro c h l o r i c a c id , 0 .5 3 3 3 N. was used f o r th e a c id and sodium h y d ro x id e, 0 .5332 N. f o r th e a l k a l i . The f i r s t ru n was a check ru n t o g iv e r e s u l t s o f th e a c id b e in g added t o 50 c c . o f d i s t i l l e d w a te r, sm all amounts a t a tim e and th e co rresp o n d in g p o t e n t i a l d if f e r e n c e a c ro s s th e c e l l was m e asu red . The pH v a lu e was d eterm in ed d i r e c t l y by th e fo rm u la : V o 1 j s * — e pH r --------- s ------ - ; .0001983 T. 1 J u l i u s G ra n t, o n . c i t .. p . 144. 36 ”2" r e p r e s e n ts th e p o t e n t i a l d if f e r e n c e i n v o l t s , "e* th e v o lta g e of th e calom el c e l l which i s v a r i a b l e due t o tem per a t u r e , and "T" i s th e a b s o lu te te m p e ra tu re o f th e s o l u t i o n a t th e hydrogen e l e c t r o d e . When th e a c id was p l o t t e d a s a b s c is s a s and th e c o r r e s ponding pH v a lu e s a s o r d in a te s , th e low er p o r tio n of cu rv e (10) was th e r e s u l t . In o rd e r t o o b ta in th e r e s t o f th e c u rv e , a new sample of w a te r was u se d and a l k a l i was added in a s im i l a r maner a s th e a c i d . The r e s u l t s were p l o t t e d a s b e fo r e , on th e same g raph form ing th e u p p e r p a r t of th e c u rv e . T his c u rv e i s v e ry a b ru p t showing t h a t w ater h a s no b u f f e r v a lu e a s i s a l s o shown i n g raph ( 2 4 ). Hext th e v a r io u s v e g e ta b le p ro d u c ts w ere t i t r a t e d . In each c a s e t h r e e gram s of th e powdered v e g e ta b le was made up t o 50 c c . w ith d i s t i l l e d w a te r, and a llo w e d t o s ta n d f o r a p p ro x im a te ly two m in u tes b e f o r e t i t r a t i o n . F i t s t t h e a o id was added as b e f o r e , and r e s u l t s ta b u la t e d a s shown i n t a b l e s (■10) t o (3 3 ), th e n t o a new sam ple th e a l k a l i was added under th e same c o n d i tio n s . Thus each graph r e p r e s e n ts th e a c id r e s i s t i n g power a s shown by one sample an d th e a l k a l i r e s i s t in g power a s shown by a s im ila r sample u n d e r s im ila r c o n d i tio n s . D u p lic a te ru n s were made on each p r o d u c t. The c o l l o i d a l s o l u t i o n was v e ry h a rd to keep from form ing b u b b le s and f r o th in g over th e s id e of th e v e s s e l due t o th e hydrogen b ein g passed th ro u g h th e s o lu t io n , which w ould reduoe th e c o n c e n tr a t io n . 37 U su a lly a g i t a t i o n from an e x t r a s t i r r i n g ro d would overcome t h i s t r o u b l e . Care a l s o had to be ta k e n t o in s u re a g a in s t p o iso n in g of th e p la tin u m i n th e hydrogen e l e c t r o d e . Between each ru n th e e l e c t r o d e was c le a n e d o ff i n a q u a - r e g ia and r e p l a t i n i z e d in s ta n n ic c h lo r id e s o lu tio n # The fo llo w in g p ro d u c ts were t i t r a t e d : la b o r a to r y de h y d ra te d sp in a c h , l e t t u c e and c e le r y , and com m ercially de h y d ra te d s p in a c h . Most of th e ru n s were made a t 35° C. w ith th e e x c e p tio n of sp in a c h i n which th re e d i f f e r e n t te m p e ra tu re s were u s e d . The f i r s t te m p e ra tu re was 35° C. or ab o u t room te m p e ra tu re , th e second was 33° C. w h ile th e t h i r d was 3 7 .5 ° C. j u s t body te m p e r a tu r e . I t was found t h a t th e b u f f e r v a lu e rem ained q u ite c o n s ta n t a t a l l te m p e r a tu r e s . However a s i s shown i n graph (34) th e sp in a c h s o lu tio n had q u ite a n o tic e a b le b u f f e r v a lu e a t a l l tim e s . T his may a l s o be n o tic e d by th e d i s t i n c t i v e S-shaped t i t r a t i o n cu rv e which i s a t no tim e v e ry e r e c t • A ll of th e v e g e ta b le s showed a d e f i n i t e b u f f e r v a lu e o r te n d e n c y . P la c in g them i n t h e i r o rd e r o f d e c re a s in g b u f f e r t v a lu e would a rra n g e them a s f o llo w s : sp in a c h , com m ercial sp in a c h , l e t t u c e , and c e le ry # ... . . : - - 38 j % m 9 i p o^L t * T a r l B l l a » * 44 #A Q T A X 9 t > (' * i t ; 0 i i s < i i > i o c c. c C c. o 0 1 X o 9 H C l f J m ■ - T ItT a t i O 'n (: u i - V ( 1 M * 1 • o 0 / a t e r 15 °c. - 39 CHECK RUN WITHOUT VEGETABLE TABLE X c c . Base M i l l i - Y o lts , PH c c . A cid M i l l i v o l t s . pH 0 .0 573 5 .5 0 .0 573 5 .5 0 .3 5 889 1 0 .9 0 .3 5 365 3 .0 0 .5 913 1 1 .3 9 .5 353 1 .8 1 .0 936 1 1 .6 1 .0 341 1 .6 1 .5 949 1 1 .8 1 .5 336 1 .5 3 .0 956 1 1 .9 3 .0 333 1 .4 3 .5 960 1 3 .0 3 .5 339 1 .4 3 .0 964 13.1 3.0 336 1 .3 3 .5 968 1 3 .3 3 .5 334 1 .3 4 .0 971 1 3 .3 4 .0 333 1 .3 5 .0 977 1 3 .4 5 .0 319 1 .3 6 .0 983 1 3 .4 6 .0 316 1 .1 7 .0 985 1 3 .5 7 .0 314 1 .1 8 .0 988 1 3 .5 8 .0 311 1 .0 9 .0 993 1 3 .6 9 .0 310 1 .0 1 0 .0 994 1 3 .6 1 0 .0 307 1 .0 - - - - - ■ ■ - 40 - § 1 . # a a t 4 S i f P j 0 £ X Q * JL f - 4 v A Y A X o i \ i \ 4: i o / * 1 4 : ( ; i > 4 0 c c. 4 * c c . P, A t - V 9 & £ i ' T i t r a t i o R t ’* 4 1 w e V o . , \ 1 > t n a c h ( ► r a “ V C. 41 SPINACH 2 5 ° C. T A B L E X I cc. Base M illi volts . pH cc. Acid M illi volts. pH 0.0 600 6.0 0.0 598 5.9 0.5 643 6.6 0.5 562 5.3 1.0 686 7.4 1.0 535 4.8 1.5 747 8,4 1.5 517 4.5 2.0 788 9.1 3.0 505 4.3 3.5 819 9.6 2.5 498 4.3 3.0 845 10.1 3.0 484 4.0 3.5 860 10.3 3.5 473 3.8 4.0 886 10.6 4.0 463 3.6 5.0 909 11.1 5.0 446 3.3 6.0 938 11.5 6.0 430 3.1 7.0 939 11.6 7.0 413 3.8 8.0 946 11.7 8.0 397 3.5 9.0 955 11.9 9.0 381 3.1 10 .0 963 13.0 10.0 370 1.9 11.0 968 13.1 11.0 360 1.8 12.0 973 12.3 13.0 353 1.7 T A B L E XII 0.0 600 6.0 0.0 600 6.0 0.5 633 6.5 0.5 566 5.4 1.0 680 7.1 1.0 536 4.8 1.5 734 8.2 1.5 514 4.5 2.0 785 9.1 3.0 499 4.3 3.5 818 9.6 3.5 488 4.0 3.0 848 10.1 3.0 478 3.9 3.5 867 10.4 3.5 466 3.7 4.0 880 10.7 4.0 456 3.5 5.0 906 11 .1 5.0 439 3.3 6.0 937 11.5 6.0 431 3.9 7.0 942 11.7 7.0 403 3.6 8.0 953 11.9 8.0 388 3.4 9.0 960 13.0 9.0 374 2.1 10 .0 965 12.1 10.0 363 3.0 12.0 974 12.3 13.0 348 1.7 : - - ‘ * - ! " » ' . ; . . . ■ - 43 • ■ ' f t - a r 11 iYV- • 3: ■ * f » 1 A JV 9 7 A J o i r < r i ; S c? J / 2 . k t► e 1 0 c m + * .......i£ c c. © v > X ..v c' " 7 o J * K •f « x Ti t r ,3 1 f 0 7 1 Cl x r Vfi - N 0.1 e s / j i 7 1 3 c H t t ' ° C -----. r t is I X 1 9 t + 1m a 4 * 5 **> 1 A 0 7 A s o ( > f i ' i & » Ji » 2 t ( ; i * i o c c . /* c c - Q r* 0 A n < ■ * V / o c 1 2 T i t r ii t i o n C l I T Vre f o . j : 3 S /« r n ac A i v . 44 SPINACH 35° C. T A B L 2 XIII c c . Base M illi volts . PH CO. Acid M illi volts.. pH 0.0 59k 5.8 0.0 565 5.4 0.5 616 6.3 0.5 536 4.7 1.0 663 7.0 1.0 504 4.3 1.5 715 7.9 1.5 485 4.0 3.0 760 8.7 3.0 471 3.8 3.5 791 9.3 3.5 461 3.6 3.0 800 9.4 3.0 449 3.4 3.5 831 9.8 3.5 439 3.3 4.0 838 10.0 v 4.0 430 3.1 5.0 880 10.7 5.0 410 3.7 6.0 903 11.0 6.0 389 3.4 7.0 915 11.3 7.0 379 3.0 8.0 933 11.4 8.0 365 1.8 9.0 930 11.5 9.0 341 r.6 10.0 936 11.6 10.0 343 1 .5 11.0 944 11.7 11 .0 334 1.4 13.0 949 11.8 13.0 338 1.4 SPINACH 330 c . TABL2 XIV 0.0 600 5.9 0.0 600 5.9 0.5 636 6.4 0.5 553 5.3 1 .0 653 6.8 1.0 536 4.7 1 .5 703 7.6 1.5 510 4.5 3.0 870 8.6 3.0 500 4 .3 3.5 800 9.3 3.5 485 4.1 3.0 834 9.7 3.0 474 3.8 3.5 848 10.0 3.5 465 3.7 4.0 863 10.3 4.0 455 3.5 5.0 896 10.8 5.0 436 3.3 6.0 915 ' 11.1 6.0 418 3.9 7.0 935 11.5 7.0 400 3.6 8 .0 944 11.6 8.0 384 3 .3 9.0 951 11.7 9.0 373 3.1 10.0 957 11.8 10.0 363 1.9 11.0 963 11.9 11.0 354 1.8 13.0 967 13.0 13.0 345 1.7 .. 1 5 11 12 T 11 • V&V 5 ^ a J k £ # A V/ X v Q T A / I 0 II ( > i i O 9 / ! i ‘ < > 4> 1 o c c . A / Cc . o A T • £ t T o •* K * 1 * ret t a t i e n C a: r V < ' N o . l f $ pi i t a < 7** c. ■ Tchl : - - 9 1.2 £ K* £ u ? £ V a A 4 ” 0 u >?1 l ? l v # € r* \ «. £ V c * > q 0 / 0 t \3 I9 } 'r ! t / ■ f t r 9 i> (J 0 r x > ^ L h A f 1 0/ r r * (S > / / 4 : C 7 * X t - : 9f :: . : . : SPINACH 32° 0 47 T A B L E X V oc • Base M illi volts, pH cc. Acid M illi volts . pH 0.0 600 5.9 0.0 597 5.9 0.5 631 6.4 0.5 557 5.3 1.0 665 7.0 1.0 533 4.8 1.5 718 7.9 1.5 514 4.5 3.0 762 8.6 2.0 500 4.3 2.5 694 9.1 3.5 488 4.1 3.0 818 9.5 3.0 479 3.9 3.5 837 9.8 3.5 468 3.7 4.0 855 10.1 4.0 459 3.6 5.0 882 10.6 5.0 443 3.3 6.0 906 11.0 6.0 435 3.0 7.0 935 11.3 7.0 410 3.8 8.0 936 11.5 8.0 393 3.5 9.0 945 11.6 9.0 380 3.3 10.0 951 11 .7 10.0 366 2.0 11.0 956 11.8 11.0 356 1.8 12.0 962 11.9 13.0 349 1.7 S P IN A C H 37.5° C. T A B L E X V I 0.0 590 5.8 0.0 600 5.9 0.5 635 6.5 0.5 561 5.3 1.0 725 7.9 1.0 535 4.9 1.5 773 8.8 1 .5 515 4.6 2.0 833 9.7 3.0 498 4.3 3.5 840 9.8 3.5 487 4.1 3.0 854 9.9 3.0 476 3.9 3.5 878 10.4 3.5 463 3.7 4.0 899 10.8 4.0 454 3.5 5.0 925 11.3 5.0 431 3.2 6.0 941 11.5 6.0 414 2.9 7.0 951 11 .6 7.0 397 2.6 8.0 960 11.7 8.0 366 2.4 9.0 967 11.8 9.0 356 2.2 10.0 970 11.9 10.0 347 3.0 11.0 975 12.0 11.0 340 1.8 12.0 978 12.1 12.0 334 1.6 48 Tt trati r y e O 71 pi.t » a 49 1 V f ? t « * c f f Q * i 2 2 U 0 7 A J 0 i > < ; 4: j O i /; > I : ( : £I X 0 c c. C C * 6 A V \C y / *± % 0 p h * 1 * J L --------------------------- n r r a ■ n c u r i/e A'o .£ 7 3 ^ i 7 7 a c f t < 3 / . £ V. j i t • - - w i i _ i________________ i 50 SPINACH 3 7 .5 ° C. T A B L E XVII C O • Base M illi volts. P H cc. Acid M illi volts, pH 0.0 580 5.6 0.0 596 5.9 0.5 616 6.0 0.5 - 556 5.1 1.0 653 6.6 1.0 534 4.9 1.5 714 7.8 1.5 515 4.5 2.0 783 8.9 3.0 501 4.3 2.5 813 9.3 3.5 489 4.1 3.0 836 9.6 3.0 478 3.9 4.0 863 10.3 4.0 456. 3.6 5.0 894 10.7 5.0 438 3.3 6.0 905 10.9 6.0 418 3.0 7.0 917 11 .1 7.0 401 3.7 8.0 933 11.3 8.0 387 3.4 9.0 944 11.5 9.0 371 3.2 10.0 951 11.6 10.0 360 3.0 11.0 953 11.7 11 .0 351 1.9 13.0 964 11.8 13.0 345 1 .8 SPimCH 37.50 c . T A B L E XVIII 0.0 594 5.9 0.0 600 5.9 • 0.5 635 6.5 0.5 563 5.3 1.0 672 7.1 1.0 540 5.0 1.5 735 7.9 1.5 533 4.7 2.0 773 8.8 3.0 509 4 .5 2.5 805 9.3 3.5 498 4.3 3.0 827 9.7 3.0 488 4 « 1 4.0 859 10.1 4.0 468 3.8 5.0 881 10.5 5.0 454 3.5 6.0 900 10.8 6.0 437. 3.3 7.0 910 10 7.0 433 3.0 8.0 932 11.3 8.0 405 3.8 9.0 ' 932 11.3 9.0 393 3.6 10.0 943 11.5 10.0 377 3.4 11.0 953 11.6 11.0 367 3.2 13.0 957 11.7 13.0 257 2.2 ■ - ■ . 1 . . ■ : . t::- . - . ...: ... . - j 4 . - - * 51 ■ . . ■ ■ ■ - - 0 f lf - - t 9 t m £ 1 4 4 ** 4 /> t Q T A X 0 (* < \ \ I i O » / 1 : 4[ < : j\ s e C c . r / c c. iC” w A V JT * X sJ P c f ■ J L t Ti t r z . t i < > 7) C a r Nc 4 8 s t p i ?? 4 < :fc : i..w ' 57: f c • - - ■ ■ ■ - ..... . ; ...... - 53 - f * 1? t i £ 1 Q a m *x //» /V 0 A 1 o I » I; ^ t i O I ] i \ 4 : < > i J 1 a c c. ec. - |g l / X ) £ J w * f JL T (.1■ r a 11 < ‘ T T t Z ui " V € ' (\f 1 % i 4 ? c >7W i )/sl /? ^ < : h Z6 . P C • C O M M . SPIHACH 25° C. 53 T A B L E X IX cc. Base M illi volts, pH cc. Acid M illi volts pH 0.0 565 5.4 0.0 550 5.1 0.5 602 6.0 0.5 525 4.7 1.0 653 6.8 1.0 503 4.3 3.0 767 8.0 1.5 483 4.0 2.5 805 9.4 3.0 464 3.7 3.0 839 9.9 3.5 447 3.4 3.5 863 10.4 3.0 431 3.1 4.0 887 10.8 3.5 415 3.8 5.0 914 11.3 4.0 400 3.6 6.0 933 11.5 5.0 375 3.1 7.0 943 11 .7 6.0 357 1.8 8.0 953 11.9 7.0 350 1.7 9.0 959 13.0 8.0 344 1 .6 10.0 966 13.1 9.0 338 1.6 11 .0 970 12.3 10.0 334 1 .5 12.0 976 13.3 11.0 330 1.4 13.0 979 13.3 13.0 327 1.3 L E T T U C E 35° C. T A B L E X X 0.0 580 5.6 0.0 585 5.7 0.5 634 6.5 0.5 535 4 .8 1.0 680 7.3 1.0 499 4 .3 1.5 730 8.1 1.5 475 3.8 3.0 769 8.8 3.0 459 3.5 3.5 804 9.4 3.5 446 3.3 3.0 840 10.0 3.0 436 3.2 3.5 870 10.5 3.5 429 3.1 4.0 887 10.8 4 .0 433 3.9 4.5 889 11.0 4.5 413 3.8 5.0 910 11.3 5.0 405 3.7 6.0 934 11 .4 6.0 396 3.5 7.0 937 11.6 7.0 385 3.3 8.0 946 11.8 8.0 373 3.1 9.0 951 11.9 9.0 370 3.0 10.0 956 13.0 10.0 367 3.0 13.0 968 13.1 12.0 359 1.9 54 cc. n CiLrve___ 11 « c t: L 5 aC " • ' 5 5 - 1 % * w - r * C 1 1 o£- I Q 1 a atv 0 7 A i 0 i* tr ii i o / 1 : i < > (» i o cc. i f * cc. o 4 * • * \ $£> v nc^ 1 J * T\1 r a t \ 0 1\ Cu. rv/< ) A to. 2 J i e t "uc ■ e i15* *c. LETTUCE 35° 0 . T A B L E X X I 00 . Base M illi volts P H cc • Acid M illi volts p H 0.0 583 5.8 0.0 580 5.6 0.5 630 6.4 0.5 541 4.9 1.0 671 7.3 1.0 500 4.3 1.5 730 8.3 1.5 477 3.8 3.0 768 8.8 3.0 455 3.5 3.5 800 9.3 3.5 437 3.3 3.0 835 9.9 3.0 434 3.0 3.5 863 10.4 3.5 410 3.7 4.0 881 10.7 4.0 397 3.5 5.0 908 11.1 5.0 375 3.3 6.0 934 11.4 6.0 360 1.9 7.0 934 11 .6 7.0 347 1.7 8.0 944 11.8 8.0 343 1.6 9.0 950 11.9 9.0 337 1 .5 10.0 956 13.0 10 .0 333 1.5 13.0 966 13.1 13.0 337 1.4 C E L E R Y 350 C. T A B L E XXII 0.0 585 5.8 0.0 585 5.8 0.5 643 6.6 0.5 540 4.9 1.0 693 7.5 1.0 513 4.6 1.5 750 8.5 1.5 493 4.1 3.0 774 8.9 3.0 467 3.7 3.5 834 9.7 3.5 453 3.5 3.0 873 10.6 3.0 439 3.3 3.5 897 10.9 3.5 435 3.0 4.0 914 11.3 4.0 409 3.7 5.0 938 11.6 5.0 387 3.4 6.0 953 11 .9 6.0 368 3.0 7.0 961 13.0 7.0 348 1.8 8.0 968 13.1 8.0 343 1.7 9.0 971 13.3 9.0 338 1.6 10.0 977 13.3 10.0 334 1.5 13.0 986 13.5 13.0 330 1.4 j " " - - - 07 # S P ■ : ■ * V j # « r <r« H =e a • » A v 7 a 1 O i! (> i ; O » / i > i ! • < ; e> j o C c. c c c . o A X v \ J i f 2 ■ T i t T ^ LjLo £ e n C . a r < 'e N 0* £’2 1 e r y rc. r / y z t - 58 f c - f 9 - J 3 J ? T J J * f t z z a X L 10 o 1 Cl X 0 i * i : i i i O > I j ! 4i < * « ! i o c c . ...£ c c . o c w A I t •? V* £m 1 J> T it r a . t i e 71 £ U. r v e Ni K 2* J C © 1 © r y 9 i *r ° c . - - / 59 C E L E R Y 25° C. T A B L E XXIII cc • Base M illi volts - PH cc • Acid M illi volts pH 0.0 585 5.7 0.0 585 5.7 0.5 643 6.7 0.5 535 4.8 1.0 698 7.5 1.0 510 4.4 1.5 749 8.4 1.5 487 4.0 2.0 782 9.0 2.0 470 3.8 2.5 820 10.6 2.5 455 3.5 3.0 873 10.9 3.0 440 3.3 3.5 ' 894 11.2 3.5 430 3.1 4.0 914 11.6 4.0 418 3.9 5.0 937 11.8 5.0 397 2.5 6.0 948 12.0 6.0 375 3.2 7.0 957 12.1 7.0 363 2.0 8.0 963 12.1 8 .0 354 1.8 9.0 968 12.2 9.0 344 1 .7 10.0 972 12.3 10.0 340 1.5 12.0 978 12.3 12.0 332 1 .4 50 M V> VJ «* SUM M ARY AND CONCLUSION I n t h i s r e s e a r c h th e l i t e r a t u r e was se a rc h e d to a s c e r t a i n p re v io u s work on d e h y d r a tio n o f v e g e ta b le s A sm all d e h y d ra tio n p l a n t was s e t up and many p ro d u c ts were s u c e s s f u l l y d e h y d ra te d . D ehydrated sam ples were p r e p a r ed of th e f o llo w in g : sp in a c h , d a h lia s , l e t t u c e , c e le r y , c a r r o t s , to m ato es and o ra n g e s . These sam ples were a l l i n good c o n d itio n a f t e r a p e r io d of one y e a r . I t was proved th a t p u lv e r iz e d d e h y d ra te d p ro d u c ts have b u f f e r te n d e n c ie s tow ard b o th a c id s and b a s e s . T his a c tio n i s l i k e l y due to th e f a c t t h a t f in e n e s s of s u b d iv is io n f r e e s th e b u f f e r s a l t s r e t a i n e d in th e p l a n t c e l l . A lso th e c h lo ro p h y ll and o th e r s u b s ta n c e s p r e s e n t c a u se b u f f e r e f f e c t s . T his r e s e a r c h shows t h a t th e d e h y d ra tio n o f v e g e ta b le s i s com m ercially p r a c t i c a l . The p ro d u c ts occupy l i t t l e sp ace, keep w e ll and a r e th u s v e ry good s u b s t i t u t e f o r f r e s h v e g e t a b le s d u rin g th e s e a s o n when th e s e a re n o t a v a i l a b l e . De h y d ra te d v e g e ta b le s have c e r t a i n p h y s io lo g ic a l a d v a n ta g e s . The f in e n e s s of s u b d iv is io n makes p o s s ib le a v e ry much h ig h e r c o e f f i c i e n t o f d ig e s tio n making a v a ila b le p r a c t i c a l l y a l l of th e m in e ra l s a l t s o f th e v e g e ta b l e . I t was shown a l s o t h a t such p ro d u c ts have a c e r t a i n a c id n e u t r a l i z i n g power due to b u f f e r a c tio n when f i r s t in g e s te d — even b e f o r e m e ta b o lism . These p ro d u c ts a r e in such a c o n d itio n t h a t th e y r e a d i l y form an em u lsio n and may a d m in is te r a i d to th o s e who from stomach or i n t e s t i n a l u l c e r s can n o t t o l e r a t e o rd in a ry f ib o ro u s veg e t a b l e s * I t would a p p e a r t h a t th e r e sh o u ld be a g r e a t f i e l d f o r th e u s e of th e s e v e g e ta b le p r o d u c ts , e s p e c i a l l y when combined w ith o th e r fo o d p r o d u c ts . BIBLIOGRAPHY OH DEHYDRATION B rin c h and S pehr, "Drying F r u i t s . " French P a t . 696.910, A p ril 15, 1930. Chem. Aba.. V o l. 35, p . 3783, 1 931. C h r i s t i e , A.. W. and N ic h o ls, P . F ., "Drying Cut F r u i t s . " C a l i f . A a r. E x p t. S t a . B u l l . 484, p p . 1 -4 6 , 1930. Chem. A bs.. V o l. 24, p . 3810, 1930. S k ro th , C. V ., " F r u it and V e g e ta b le D eh y d ratio n From a Tech n i c a l S ta n d p o in t." Am. J . o f Pub. H e a lth . V o l. 8, p p . 305 7, 1918. Chem. A b s.. V o l. 13, p . 1319, 1918. F a lk , G ., "C arb o h y d rates of F re sh and D ehydrated V e g e ta b le s ." I n d . Eng. Chem.. V o l. 11, p . 1133, 1919. F a lk , G ., F ra n k e l, E . M. and McKee R . H ., "Low T em perature Vacuum Food D e h y d ra tio n ." I n d . Eng. Chem. . V o l. 11, p p . 4 6 5 -6 , 1 9 3 3 . F ra p s, G. S. and T r e ic k l e r Ray, " E ffe c t of S to ra g e on V itam in "A" I n D ried F o o d s." I n d . Eng. Chem., V o l. 35, 1036-9, 1919. G ore, H. C. and M angels, C. E ,, " R e la tio n of M o istu re C ontent To The D e te r i o r a tio n Of R aw -dried V e g e ta b le s Upon Comm on S to r a g e ." U. S . B ur. Of Chem., J . I n d . Eng. Chem.., . V o l. 13, p p . 533-4, 1931. Chem. A b s ., V o l. 15, p . 3934, 1921. G oubert, A. A ., "D rying V e g e ta b le s ." U. S.. P a t . 1. 305,599, 1919. Chem. A b s .. V o l. 13, p . 3113, 1919. H arriso n ,' B . S ., "D rying F r u i t s and V e g e ta b le s , " U. S.. Pat_. 1 ,3 8 7 ,8 1 0 , 1 9 3 1 . Chem. A ba. V o l. 15, p4033, 1 9 3 1 . Lormand, C ., " C a ta ly s ts o f D e h y d ra tio n ." I n d . Eng. Chem.. V o l. 16, p . 978, 1934. M angels, C. E . and G ore, H. C ., "The E f f e c t of Heat On D if f e r e n t V e g e ta b le s ." B u r. o f Chem., U, S.. D e p t. of A gri ., Wash. D. C. I n d . Eng,. Chem., V o l. 13, p . 535, 1 9 3 1 . Moore, C. C ., " S u lf u r iz in g , D eh y d ratio n and R e s u lfu rin g F r u i t . " U. S . P a t . 1 .6 3 3 .8 3 3 . 1937. Chem. A bs. V o l. 3 1 , . p . 3748, 1937. 64 H ic k o ls , P . F . and G ro ss, C. R ., "Methods o f P re p a rin g Veg e t a b l e s For D e h y d ra tio n ." B ur. of Chem. U. S. D ept, of A g r i., Chem. Age„ Hew York: 1931, V o l. 39, p p . 1 3 9 -4 1 . Chem. A bs. V o l. 15, p . 3934, 1931. Owen, B . J . , "D eh y d ratio n of V e g e ta b le M a te r ia ls Such As Root and S u rfa c e C ro p s." U. S.. P a t . 1. 781. 473. 1931. Chem. A bs. V o l. 35, p . 154, 1931. » . . . . . . , "D rying V e g e ta b le s Or O ther O rganic M a t e r i a l s ." B r i t . P a t . 367. 303. 1 9 3 5 . Chem. A bs. V o l. 33, p . 1199, 1938. Sykes, G. A ., "D rying F r u i t s and V e g e ta b le s ." B r i t . P a t . 333.740. 1938. Chem. A bs. V o l. 34, p . 3291, 1930. BIBLIOGRAPHY O H BUFFSRS B a ile y , C. H. and P e te rs o n , A. C ., " S tu d ie s of Wheat F lo u r G rades— B u ffe r A ctio n of W ater E x t r a c t s . " I n d . E ng. Chem. V o l. 13, p . 916, 1931. \ B r i t t o n , H ubert T. S ., " P r i n c ip le s of V o lu m e tric A n a ly s is ." Hydrogen Io n s . Hew York: D. Van H o stran d C o., 1939. p p . 5 0 -8 . C la rk , W. M a n sfie ld , " B u f f e r s ." The D e te rm in a tio n of Hydro gen Io n s. B a ltim o re : The W illiam s and W ilk in s C o., 1938. p p . 1 3 3 -3 . Getraan, F re d e ric k H ., "E le c tro m o tiv e F o rc e ." O u tlin e s of T h e o r e tic a l C h em istry . Hew Y ork: Jo h n W iley and Sons, 1938. p p . 5 7 1 -3 . \ G ra n t, J u l i u s , "B u ffe r S o l u t i o n s ." The Measurement of Hydrogen Ion C o n c e n tra tio n . Hew York: Longmans G reen C o., 1 9 3 0 . p p . 1 9 -2 3 . Hawk, P . B. and Bergeim ^ O la f, " R e s p ira to ry M etabolism and n e u t r a l i t y R e g u la tio n s ." P h y s io lo g ic a l C h em istry . P h ila d e lp h ia : P. B l a k i s t o n 's Son and C o., 1 936. „pp. 4 3 0 -3 . ... I n g o ld , T erence C ., "H ydrogen-Ion Phenomena In P l a n t s . " P ro - to p la sm a , V o l. 9, p p . 441-6, 1930. Chem, A bs., V o l. 3 5 ,. p . 4034, 1931. 6 5 K e e le r, 2 . A ., "The A p p lic a tio n of Io n C o n c e n tra tio n M easure m ents To th e C o n tro l of I n d u s t r i a l P r o c e s s e s ." J . I n d . . Eng. Chem. V o l. 14, p p . 395-9, 1933. K o lp ste g , P . 2 . , "Some P r a c t i c a l A sp ects of Hydrogen 2 1 e c tro d e 1 M easurem ents." I n d . Eng. Chem. V o l. 14, p p . 399-496, 1933. Lew is, W illiam C. McC., " S o lu tio n s of R eserv e A c id ity and A l k a l i n i t y . " Text-B ooks o f P h y s ic a l C hem istry. New York: Loqgmans G reen a n d .C o ., 1939. p p . 3 6 3 -3 . L e u th a rd t, F ra n z , "B u ffe r C a p a c ity and P la n t J u c i e s . " K o llo - idchem B e c h e fte . V o l. 35, p p . 1 -6 8 , 1 9 3 7 . Chem. A bs. V o l. 33, p . 445, 1938. M ic h a le lis , L ., "Laws of E l e c t r o l y t i c D is s o c i a t i o n ." Hydro gen Ion C o n c e n tra tio n . B a ltim o re : The W illiam s and W ilk in s C o., 1 936. p p . 43— 5 8 . P h i l i p , J . C ., " E le c tro m o tiv e F o rc e ." P h y s ic a l C h e m istry . New York: Longmans Green And Co., 1 9 3 5 . p p . 3 5 5 -8 . Van S ly k e, Donald D ., "The N ature and Mode of B u ffe r V a lu e s ." o f B io . Chem., B a ltim o re , 1933. V o l. 53, M ay-June. pp • 5 3 5 -6 8 . Washburn, 2 . W., "The Theory and P r a c tic e o f th e Io d o m e tric D e te rm in a tio n o f A rsen io u s A c id ." J.. o f Am. Chem. S o c.. V o l. 30, p . 36, 1 9 0 8 .

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Creator Dailey, L. R (author)

Core Title The dehydration of vegetables

Degree Master of Science

Degree Program Chemistry

Publisher University of Southern California (original), University of Southern California. Libraries (digital)

Tag agriculture, food science and technology,OAI-PMH Harvest

Language English

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Permanent Link (DOI) https://doi.org/10.25549/usctheses-c17-786818

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