Diseño y adaptación de la huerta para el envejecimiento

The c ompari s on o f 0 . 30-H perchloric ac i d with 0 . 1 2-l\'1 and 0 . 73-H t ri chlo roac et ic acid as preci pit ant s for case in-rennet reactions has shovvn that perchloric acid quenches the react i o n s similarly t o 0 . 1 2-M

t ri chloroac e t ic acid

.

Thus perch loric ac i d c an be use d

a s a prec ipitant t o measure t h e rat e of

h

ydrolysis o f

t h e labi le ph enylalanine -m e th i onine bond of k

-

c ase in

.

Th e rat i o o f reaction pro ducts soJ.uble in 0 . 3 0-H

perch l o ri c ac i d t o tho se s o luble in 0 .

1 2-H

t r i ch l o ro a c e t i c acid i s gre at e r than 1 . 0 and there fore a larger absorbanc e reading i s obt aine d wh en perchlo ri c

ac i d i s us e d as th e pre c ipi t ar:tt for case in-rennet

re act i ons . The large r abso rbance value give s a s t e e pe r curve against tir·" e and h enc e a J:lore accurate e s t i ·nat e

o f the st age of the reacti o n

.

It appears that per­

ch lori c a c i d i s a m o st suit able pre c i pitant f o r c a s e in­ r ennet rea,c t i ons and allowe

d

th e d eve l opmen-t; of the assay rneth o d des c r i bed above .

The assa�r e s t imat e d reruw t act ivity by measuring

th e quant ity of p e pt i d e s rele as ed in one minute from

s o dium cas einate under cont ro l l e d c ondi t i ons and has several advantages over oth e r m ethods of as say ing rennet act i vity . In part i cular the m e thod utilises a me asure d

end

-

po int wh i ch i s more reliable than th e o bs e rve d end­ po int of s everal other methods

(

Be rri dge , 1 9 5 5 ;

Ernst rorn , 1 95 8 ; Doulliard & Ri badeau Duma.s , 1 970 ) and c an m easure rennet act ivity one fo rt i eth that n o rmally r.1 e asure d by a Tl1 i lk c oagulat i on as say at least as

accurat ely. No re fe renc e rennet i s require d as one bat ch of subst rat a is calibrate d against anoth e r bat ch

and as rennet act ivity i s m e asured direct ly i t i s not c o�plicat e d by th e secondary phase of � i lk c oagulati on

.

C ondit i ons for the as s ay are s irnilar t o tho s e fotmd i n c om"' ercial u s e of. rennet and th is i s of value when

H easurer:1 ent o f renne t a_ctivity i s o bt aine d _{over a ranc;e} of act_{ivi t i}e s wh i ch are _{wide t o allow a relia.bl e} es_timate _{o f ac t ivity from s erial} d i lut i ons _{o f a rennet} of unknown act ivi ty . Th e _{as s ay c an be perf o rm e d i n} large num bers qui t e rapidly a.nd require s no spec i al e quipm ent .

All rennet a s s ay s report ed in thi s th e s i s vvere c onduct e d wi th th e _{above � e th o d un l e s s otherw i s e}

CHAPrER I I I

ENZYHE PURI:FICA'r iON

7·Tost proteolytic

enzyl"'e s

c an. c oagu­

lat e

m i lk under s_uitabl

e

c ondit ions and there fore m i lk

c o e{,rt:tlat int:;

enzy, e s

have be en

obt aine d

fron1 virtuall;y

ever�r

c las s of living o reani s .,

(Ernstront ,

1 96 5 ) .

As the t:r'ao_i t i onal 111 i lk coagLJ.lat i n g enzy:rt e ,

rennin ,

is ext rac t e d from the abon1asu·.., s

o f

you_ng J"l i lk-fed calve s

(

Plac e k ,

Bavi s o t t o & Jadd ,

1 96 0 ;

C larke ,

1 9 G 9 ;

Calvy , 1 97 2 )

the stomachs o f other

animals

have been widely inve st i eat ed as

a source

of m i lk c oagu.lat ing enzymes .

The

c omrn e rc ial l;yr more feas i b1e sourc

e

s inve s t i eat e d inc lude

cattle

( No rthrup , 1 93 3 ;

Chow

&

Kas s e l l ,

1 96 8 ;

I<'ox ,

1 9 6 9 ,

b ;

Gre e n ,

1 97 2 ) ,

ki

ds

(Yama'Tio to

&

Tak8llaGhi

1

1 9 53 ) ,

ch i ckens

(

Bohak , 1 9G 9 ;

Gre en ,

1 97 2 ) ,

svvine

(Rajo.:;aplan,

T-1o ore &

St e i n , 1 96 G )

and lar.1bs

(

Alais,

1 96 3 ;

Oruntae va

& Seitov ,

1 97 1 ;

O ' Le ary & Fox ,

1 973 ) .

The enzyme ::l ext ract e d from c alve s , kids and

young

lambs are

pre dominant ly

rennir1s

whi l e the

e n zym e s

extr

act

e

d frOP1 cattle 1 ch i ckens ,

swine

�:md ol

der larn bs

are pre don; inant ly

p

e

ps

i

ns or

a ntore

even

rt"J ixt ure

of both rennins an d

p

epsi

n

s depend ing upon the

age

of th e ani

�al

at sl

a

u

sh

ter and the nature of it s diet

In document La agricultura urbana como herramienta para el bienestar de las personas mayores del Centro de Protección Social Bosque Popular de Bogotá (página 100-104)