Ava Clark
Partner: Emma Kobelsky
B03
Nutritional Composition of Beer
Introduction:
The purpose of the experiment was to determine the nutritional composition of beer,
specifically the amounts of sugar, protein, and amino acids. This was significant because beer
can then positively or negatively contribute to an individual’s diet. The determination of
reducing sugars was completed by a DNS assay, which occurs by one molecule of 3,5-
dinitrosalicylic acid (DNS) reacts with one molecule of reducing sugar under basic conditions
and heat, which was then measured with the spectrophotometer at 540 nm to find glucose
concentration. To find protein concentration in the sample of Kokanee beer the Folin-Lowry
assay was used. It works by complexing two adjacent peptide bonds in a protein with a Cu2+ ion
(Biuret reaction) and then adding Folin-Ciocalteu reagent, which improves sensitivity of protein
detection and oxidizes the metal ion to produce a blue color that was detected with
spectrophotometry at 750 nm. The Ninhydrin assay was used to determine amino acid
concentration due to ninhydrin reacting with deprotonated primary amines, giving an orange-red
colour that was detected at 570 nm with the spectrophotometer [1]. The techniques employed for
this experiment included spectrophotometry, which works by detecting the intensity of light that
passes through the sample (absorbance), providing information on the concentration of the solute
[2]. Based off of the literature, it was hypothesized that the amount of sugars present would be
minimal because they are added in small quantities to balance sourness and bitterness [3], protein
would be present in amounts ranging from 0.15-0.40% [4], and glycine has previously been
found at 0.63 – 0.74 g/mL (0.0083-0.010 mM) [5].
, Ava Clark
Partner: Emma Kobelsky
B03
Nutritional Composition of Beer
Methods:
No changes were made to the online lab manual pp. 2.1-2.6 [1].
Results:
Table 1.0: Concentration of Glucose (mole/mL) and Corresponding Absorbance Readings at
540 nm for the DNS Assay.
Standard Curve Unknown
Tube Number 1 2 3 4 5 6 7
Glucose 0.000 0.200 0.400 0.600 0.800 0.224 0.455
Concentration
(mole/mL)
Absorbance 0.000 0.100 0.253 0.372 0.502 0.143 0.291
at 540 nm
The trend in Table 1.0 shows that as absorbance at 540 nm increases, glucose
concentration (mole/mL) for the standard curve also increase, giving rise to a linear relationship
between absorbance and glucose concentration. Unknown tube 6 falls between tube 2 and tube 3,
while unknown tube 7 falls between tube 3 and tube 4.
Table 2.0: Concentration of Protein (mg/mL) and Corresponding Absorbance Readings at 750
nm for the Folin-Lowry Assay.
Standard Curve Unknown
Tube Number 1 2 3 4 5 6 7
, Ava Clark
Partner: Emma Kobelsky
B03
Nutritional Composition of Beer
Protein 0.000 0.007 0.014 0.027 0.041 0.014 0.038
Concentration
(mg/mL)
Absorbance 0.000 0.091 0.136 0.246 0.354 0.117 0.315
at 750 nm
The trend in Table 2.0 shows that as absorbance at 750 nm increases, protein
concentration (mg/mL) for the standard curve also increase, giving rise to a linear relationship
between absorbance and protein concentration. Unknown tube 6 has the same protein
concentration as tube 2, but a lower absorbance. Unknown tube 7 falls between tube 4 and tube
5.
Table 3.0: Concentration of Glycine (mole/mL) and Corresponding Absorbance Readings at
570 nm for the Ninhydrin Assay.
Standard Curve Unknown
Tube Number 1 2 3 4 5 6
Glycine 0.000 0.005 0.015 0.025 0.013 0.028
Concentration
(mole/mL)
Absorbance 0.000 0.000 0.116 0.304 0.164 0.348
at 570 nm
The trend in Table 3.0 shows that as absorbance at 570 nm increases, glycine
concentration (mole/mL) for the standard curve also increased, giving rise to a linear
relationship between absorbance and glycine concentration. Unknown tube 5 falls between tube
Partner: Emma Kobelsky
B03
Nutritional Composition of Beer
Introduction:
The purpose of the experiment was to determine the nutritional composition of beer,
specifically the amounts of sugar, protein, and amino acids. This was significant because beer
can then positively or negatively contribute to an individual’s diet. The determination of
reducing sugars was completed by a DNS assay, which occurs by one molecule of 3,5-
dinitrosalicylic acid (DNS) reacts with one molecule of reducing sugar under basic conditions
and heat, which was then measured with the spectrophotometer at 540 nm to find glucose
concentration. To find protein concentration in the sample of Kokanee beer the Folin-Lowry
assay was used. It works by complexing two adjacent peptide bonds in a protein with a Cu2+ ion
(Biuret reaction) and then adding Folin-Ciocalteu reagent, which improves sensitivity of protein
detection and oxidizes the metal ion to produce a blue color that was detected with
spectrophotometry at 750 nm. The Ninhydrin assay was used to determine amino acid
concentration due to ninhydrin reacting with deprotonated primary amines, giving an orange-red
colour that was detected at 570 nm with the spectrophotometer [1]. The techniques employed for
this experiment included spectrophotometry, which works by detecting the intensity of light that
passes through the sample (absorbance), providing information on the concentration of the solute
[2]. Based off of the literature, it was hypothesized that the amount of sugars present would be
minimal because they are added in small quantities to balance sourness and bitterness [3], protein
would be present in amounts ranging from 0.15-0.40% [4], and glycine has previously been
found at 0.63 – 0.74 g/mL (0.0083-0.010 mM) [5].
, Ava Clark
Partner: Emma Kobelsky
B03
Nutritional Composition of Beer
Methods:
No changes were made to the online lab manual pp. 2.1-2.6 [1].
Results:
Table 1.0: Concentration of Glucose (mole/mL) and Corresponding Absorbance Readings at
540 nm for the DNS Assay.
Standard Curve Unknown
Tube Number 1 2 3 4 5 6 7
Glucose 0.000 0.200 0.400 0.600 0.800 0.224 0.455
Concentration
(mole/mL)
Absorbance 0.000 0.100 0.253 0.372 0.502 0.143 0.291
at 540 nm
The trend in Table 1.0 shows that as absorbance at 540 nm increases, glucose
concentration (mole/mL) for the standard curve also increase, giving rise to a linear relationship
between absorbance and glucose concentration. Unknown tube 6 falls between tube 2 and tube 3,
while unknown tube 7 falls between tube 3 and tube 4.
Table 2.0: Concentration of Protein (mg/mL) and Corresponding Absorbance Readings at 750
nm for the Folin-Lowry Assay.
Standard Curve Unknown
Tube Number 1 2 3 4 5 6 7
, Ava Clark
Partner: Emma Kobelsky
B03
Nutritional Composition of Beer
Protein 0.000 0.007 0.014 0.027 0.041 0.014 0.038
Concentration
(mg/mL)
Absorbance 0.000 0.091 0.136 0.246 0.354 0.117 0.315
at 750 nm
The trend in Table 2.0 shows that as absorbance at 750 nm increases, protein
concentration (mg/mL) for the standard curve also increase, giving rise to a linear relationship
between absorbance and protein concentration. Unknown tube 6 has the same protein
concentration as tube 2, but a lower absorbance. Unknown tube 7 falls between tube 4 and tube
5.
Table 3.0: Concentration of Glycine (mole/mL) and Corresponding Absorbance Readings at
570 nm for the Ninhydrin Assay.
Standard Curve Unknown
Tube Number 1 2 3 4 5 6
Glycine 0.000 0.005 0.015 0.025 0.013 0.028
Concentration
(mole/mL)
Absorbance 0.000 0.000 0.116 0.304 0.164 0.348
at 570 nm
The trend in Table 3.0 shows that as absorbance at 570 nm increases, glycine
concentration (mole/mL) for the standard curve also increased, giving rise to a linear
relationship between absorbance and glycine concentration. Unknown tube 5 falls between tube
