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Title: Semi-quantitative food tests (for reducing sugars).
Aim 1. To make the Benedict tet emi!"#antitati$e
%. To &'e&a'e di((e'ent concent'ation o( )*#coe #in)
e'ia* di*#tion
+. To etimate the "#antit, o( )*#coe -o' )*#coe/ in a ('#it
0#ice o*#tion.
B, no ,o# ho#*d 2e (ami*ia' ith the #e o( the Benedict o*#tion
hen tetin) (o' 'ed#cin) and
non!'ed#cin) #)a'. Yo# ho#*d 'eca** that the Benedict o*#tion
-2*#e/ i an a*ka*ine o*#tion o(
co&&e' -II/ #*&hate -C#SO3/. The a*deh,de o' ketone
)'o#& o( a monoaccha'ide #)a' i a2*e to'ed#ce C#%4ion to C#45
ite*( 2ein) o6idied to a ca'2o6,* -!COO7/ )'o#&. A 2'ick 'ed
&'eci&itate o(
co&&e' -I/ o6ide i (o'med.
Yo# ho#*d a*o 'emem2e' that the 'ed#cin) #)a' inc*#de a**
monoaccha'ide5 #ch a )*#coe and
('#ctoe5 and the diaccha'ide ma*toe.
The Benedict tet can 2e made emi!"#antitati$e5 meanin) that it i
a 'o#)h etimation o( the amo#nt
o( 'ed#cin) #)a' &'eent in a o*#tion. The (ina*
&'eci&itate i** a&&ea' )'een to ,e**o to o'an)e
to'ed!2'on ith inc'eain) amo#nt o( 'ed#cin) #)a'. -The initia*
,e**o co*o#' 2*end ith the 2*#e
o( the co&&e' #*&hate o*#tion to )i$e the )'een
co*o#'ation./
In thi e6&e'iment5 ,o# a'e )i$en a tock )*#coe o*#tion o(
knon concent'ation -%/. Uin) thi
)*#coe o*#tion and diti**ed ate' ,o# ho#*d 2e a2*e to c'eate at
*eat five di((e'ent )*#coeconcent'ation to o2tain a 'an)e o( co*o#'
ith the Benedict tet. Uin) thee co*o#' tanda'd5 the
&e'centa)e concent'ation o( )*#coe in a ('#it 0#ice o*#tion
co#*d 2e dete'mined.
Requirements:
8 tet t#2e
Tet t#2e 'ack La2e*
S,'in)e 9 1cm: and ;cm:
8 ma** 2eake'
1 *a')e 2eake' % )*#coe o*#tion
Diti**ed ate'
F'#it 0#ice o*#tion
Benedict o*#tion Sto&c*ock
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CAPE BIOLOGY UNIT 1 FOOD TESTS
;. Ue the (o**oin) (o'm#*a to )#ide ,o# on makin) di*#tion5 and
(i** in the ta2*e?
C1@1 C%@%he'e?C19 initia* concent'ation o( the tock o*#tion
@19 $o*#me o( tock o*#tion to 2e taken to &e'(o'm the
di*#tion
C%9 concent'ation o( the di*#ted am&*e
@%9 (ina* tota* $o*#me o( the di*#ted am&*e
Table !oncentrations and volume of "# glucose to be used to make
diluted solutions.
C1-/ C%-/ @1-cm:/ @o*#me o( diti**ed ate' -cm:/ @%-cm:/
%
% ; = ;
1
=.;
=.%
=.1
Note? @o*#me o( diti**ed ate' @%!@1
8. Add %cm: Benedict o*#tion to each o( the tet t#2e.
. Then add =.;cm: o( each )*#coe o*#tion and =.;cm: o( the ('#it
0#ice to the a&&'o&'iate tet t#2e
#in) a c*ean ,'in)e each time.
. Gent*, ti' the content to en#'e mi6in).
. P*ace a** 8 tet t#2e in the 2oi*in) ate' 2ath (o' e6act*, to
min#te.
1=. @e', ca'e(#**, 'emo$e a** t#2e ('om the 2oi*in) ate' 2ath
and &*ace them on the tet t#2e 'ack
11. O2e'$e the t#2e ca'e(#**, and 'eco'd ,o#' o2e'$ation in an
a&&'o&'iate (o'mat.
1%. emem2e' to dec'i2e hat concent'ation o( )*#coe ,o#' ('#it
0#ice contain.
$iscussion %uestions for !onsideration
1. hat i the Benedict tet #ed (o' and ho doe it o'k
%. hat doe emi"#antitati$e mean5 e&ecia**, in the conte6t o(
o#' aim
+. hat co*o#' a'e ,o# e6&ectin) to 'e#*t ('om a
emi"#antiati$e Benedict tet3. Dec'i2e ,o#' 'e#*t and the t'end o'
&atte'n ,o# o2e'$ed.
;. E6&*ain ,o#' 'e#*t 9 h, did ,o# )et a 'an)e o( co*o#'5
and hat a the &oi2*e
concent'ation o( ,o#' ('#it 0#ice8. E$a*#ate ,o#' &'oced#'e
in te'm o( the $a'ia2*e mani*ated and ke&t contant5
&'eca#tion
,o# took hen ettin) #& and ca'',in) o#t the
e6&e'iment
. State an, a#m&tion ,o# made a2o#t ,o#' 'e#*t and the ('#it
0#ice.. hat e'e the *imitation o( the e6&e'iment5 a e** a an,
e''o' e6&e'ienced o' antici&ated
. 7o co#*d the e6&e'iment 2e im&'o$ed o' 2e made mo'e
"#antitati$e
-% )*#coe 9 dio*$e 1=) o( )*#coe in 3==m* o( diti**ed ate' and
made #& to ;==m*./
I( % )*#coe %) )*#coe in 1==m* ate'
o =.; m* o( % )*#coe contain %)H1==m* 6 =.;m* o( )*#coe =.=1)
)*#coe -1=m) )*#coe/and =.;m* o( 1 )*#coe contain =.==;) )*#coe -;
m) )*#coe/
and =.;m* o( =.; )*#coe contain =.==%;) )*#coe -%.;m)
)*#coe/
%
