Investigation of The Bubble Foam Separation Technique To Extract Protein From Whey

American Journal of Applied Sciences 5 (5): 468-472, 2008
ISSN 1546-9239
© 2008 Science Publications

Investigation of The Bubble Foam Separation Technique To Extract Protein
From Whey

Mohammed Matouq
Al-Balqa Applied University, Chemical Engineering Department,
Faculty of Engineering Technology, P.O. BOX 4486, Amman 11131, Jordan

Abstract: Separation of proteins from whey; namely ? – Lactoglobulin and ? – Lactalbumin was
obtained using the bubble foam column technique. Two types of whey were conducted in this study;
yogurt whey and cheese whey. The effect of gas flow-rate and the height of the whey (liquid holdup)
inside the column were studied at room temperature and at constant pH of whey. Whey used here
obtained from local dairy factory as waste, and was used to investigate the performance ability of
bubble column to extract very low concentration portion from waste. Enrichment ratio showed that the
possibility of extracting protein from whey was high. Results showed that enrichment ration was
higher for yogurt whey from that of cheese whey. The results also showed that the efficiency of
separation of these proteins increased with decreasing both the air flow-rate, and wheys volume inside
the column. The maximum amount of protein obtained at air flow-rate = 0.2 Liter/ min at experimental
condition.

Keywords: Whey, Foam Separation, Bubble Column, Waste Recovery, clean technology,

environmental management

INTRODUCTION
Vorukan and Prokop[3] investigated foam

fractionation to recover low concentration cellulose
Foam fractionation is a well-documented protein
effectively. They found that separation by foam without
purification technique, which has potential use in the
surfactant could not purify since the cellulose alone
preliminary stages of the downstream processing of
could not produce enough amount of foam. Addition of
recombinant and other proteins. The advantages of the
surfactant, can increase the foamate volume and
process include, ease of operation, mechanical enhance the enrichment value.
simplicity and therefore low cost compared to existing
Foam fractionation plays an important role in
purification methods. Much research has been diverse fields both for recovering valuable solutes and
conducted using single protein solution but limited
for rejecting impurities and pollutants in dilute
work exists for protein mixtures. In order to solutions. A continuous recovery of Au(III) via foam
successfully purify one protein component from any
separation from its hydrochloric acid solutions was
mixture of proteins, the surface activities of proteins
studied using a nonionic surfactant by Akita et al [4,5,6]
must differ.
and was compared with other separation techniques.
Foam fractionation or adsorptive bubble separation
They claimed that about 90 % of Au (III) recovered in
processes had been widely applied in ineral floatation.
the foamate phase with high selective recovery of
The techniques were based on the difference of surface
Au(III) from multi-metals solution.
tension between materials to be separated. This
Kumar et. al [7] investigated separation of proteins
technique is also applied in solid wastewater treatment.
from their binary mixtures (BSA–casein, BSA–
The recovery or removal of dilute organic compounds
lysozyme) using static foams. They found out that there
contained in industrial wastewater is possible, because
is a strong interaction between the two proteins and the
organic compounds often show low surface tension and
presence of one strongly influences the adsorption of
could be enriched at air-water interface [1]
the other. The concentration of a protein in the foam
Burapatana et. al [2], used foam fractionation to recover
depends not only on the amount adsorbed at the
cellulase from an aerated water solution effectively.
interface but also on the liquid associated with it.
The addition of a surfactant increased the foamate
Perihan et al. [8] investigated the feasibility of foam
volume and enhanced the concentration of cellulase.
fractionation to separate total whey proteins and single
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Am. J. Applied Sci., 5 (5): 468-472, 2008

fractions. The investigation focused on the effects of
in the connected tube was accomplished till it reached
different process parameters such as the pH value, the
10mm external diameter at its final stage so as to break
initial protein concentration, the flow rate and the
the foam. At the end of U tube the foam was collected
addition of sodium dodecyl sulfate concentration as a
and broken down during the experiment. The lower part
surfactant. Their results showed that whey proteins
of the column was fitted with a glass frit of Pyrex
could be almost completely enriched into the foam
sintered disc of porosity 16-40µm (grade 3). Two
fraction at pH values between 2 and 3.
openings were fixed to the column to fill and empty the
Whey is the residual liquid substance that is column.
obtained by separating the coagulum from milk during
cheese making. Most commercial whey supplements
are derived from cow’s milk, which is comprised of
6.25% protein: 20% in the form of whey. It is a
complex ingredient made up of protein, lactose, fat and
minerals. Protein is the best-known component of whey
and is made up of many smaller protein sub-fractions
such as: ?-lactoglobulin,
?-lactalbumin,
immunoglobulins (IgGs), glycomacropeptides, bovine
serum albumin (BSA) and minor peptides such as
lactoperoxidases, lysozyme and lactoferrin. Each of the
sub-fractions found in whey has its own unique

biological properties.


?-Lactoglobulin binds and stabilizes fat-soluble
Fig. 1: Experimental setup for the semi-batch process
vitamins (e.g., A and D). This makes it an excellent
to separate protein from whey
source for protein fortification in low-fat nutraceutical

beverages with added fat-soluble vitamins.
Collected whey was obtained from the dairy
?
factory near to our Engineering Faculty, as waste. The
-Lactalbumin is quite similar in structure to human
whey is the product of either of cream yogurt or white
milk and is readily digestible. It is often used in infant
cheese. Before any conducted experiment the pH for
formulas to make them more like human milk. Since
both cheese whey and yogurt were measured at room
it’s not as easily heat-denatured as ?-lactoglobulin, ?-
temperature. In most conduced experiments the
lactalbumin is the protein of choice for clear temperature was found to be around 25o C. The pH for
sports/nutraceutical beverages.
whey yogurt was measured by a pH meter of (The
The goal of the current study is to examine the use
Oyster- pH/conductivity+ TDS Meter) and found to be
of foam fractionation to reduce the volume of whey
within the range of (3.5-4.25). For the cheese whey the
wastes from dairy industry via concentration.
pH found equal to 3.83.

Here the separation of protein was conducted in
Air was introduced via compressor through a
bubble foam column, the industrial application of such
plastic pipe and was measured by a flow meter. The air
techniques is in a great advantage. The bubble column
volumetric flow-rate was set at 0.2 liter/min all over the
operations and design are easier than other processes
experiment.
used to recover or separate the proteins, like ultra-
The yogurt whey that obtained from the
filtration or membrane. This can be mainly attributed to
commercial factory was poured inside column without
low operational and maintenance cost for bubble any further treatment, from the top opening. Three
column. The efficiency of proteins separation in bubble
different heights (250, 200, and 150mm) of liquid whey
column is also promising.
inside the column were selected as one of the variable

parameters to be investigated, while keeping the air
MATERIALS AND METHODS
velocity constant at 0.2 liter/min. Shortly after the

compressor started, bubble was noticed to be formed
Figure 1 shows the apparatus used to conduct
and due to the continuous airflow foam was hold up till
experimental work. The apparatus made of 50mm
it broke at the top of the collected end point. A glass
internal diameter Pyrex Glass column opened from the
beaker was adjusted to the column to collect foamate.
two sides with an external diameter of 55mm and
When the quasi-steady state assumed to be reached
650mm long. At the upper side end of the column a U-
and the collected foamate samples were taken and
tube glass was fitted to the column. A gradual reduction
analyzed by using spectrophotometer, with two cells
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Am. J. Applied Sci., 5 (5): 468-472, 2008

chamber, each 5ml volume crystals. The analysis was
lowered, enrichment value increased. Although the
done at 280 nm wavelengths. The same procedure was
difference in enrichment value can not be noticed
repeated for the cheese whey.
significantly over the increasing air flowrate range from

0.911 to 1.45 l/min at the same liquid hold.
RESULTS AND DISCUSSIONS
It is clear that the maximum air flowrate was

1.85l/min, for all cheese whey volumes. This indicates
Yogurt Whey: Figure 2 shows that when decreasing air
that above this value, no separating for protein from the
flowrate, the enrichment value is increasing. The figure
whey can be obtained. The reason can be attributed to
also reveals that the best separation for protein obtained
the fact that, when the air flowrate increases the chance
at air flowrate of 0.20 l/min. No experimental works
for the protein molecules to be absorbed at the bubble
were conducted below this flowrate value. Below this
surface will be less, hence all the collected foam will
value it was noticed that the whey started to leak
contain less amount of protein and this will decrease the
through the frit filter, and preventing| air from flowing
enrichment ratio. Moreover, the higher air flow will
through pipe feed. When the air flowrate reached 1.85
give bigger bubble size with less protein absorption rate
l/min, the enrichment value almost closed to 1, which
on the surface of the bubble. This leads to draw a
means that above this gas flow, the separation is almost
conclusion, at low air flowrate, better mixing for the
difficult. For this reason all experimental work will be
substances inside the column will be obtained,
conducted at a lower value of 1.85 l/min, and the
consequently there will be enough time for proteins to
maximum gas flow will be considered here at 1.45
transfer from bulk solution and to be absorbed on the
l/min. These values will consider as best working
surface of the bubble, to go upward of the top of the
conditions for air flowrates used to produce bubble
column to generate foamate. In addition to that
inside the column. Figure 2, indicates that there is a
increasing the air flowrate will have its significant
trend of decreasing in the enrichment value as the whey
effect on diffusion rate from the bulk to the bubble
volume (height of whey multiplied by the column cross
surface and consequently this will lower the enrichment
section area) increasing, while keeping the air flowrate
value.
at constant flow. The liquid holdup (el)defined here as
the volume of liquid divided by the total volume of the
empty column, consequently the gas holdup will be 1-
el. This behavior can be noticed when experimental
results re-plotted again as illustrated in figure 3

Whey of cheese: Figure 4, shows the result for the
separation of protein from cheese whey. The figure
indicates that as the whey volume increases, the
enrichment value decreases at constant air flowrate.
This result refers to the same reasons that mentioned
above for the yogurt whey. Moreover, cheese whey

produced less foam in comparison to that of whey's
Fig. 2: The effect of liquid holds up on the enrichment
yogurt. However, it was noticed that both cheese whey
value at different constant air flow rates
and yogurt whey had the same dynamic behavior

toward enrichment ratio. This can be clearly noticed by
From figures 2 and 3, it is clear that the
comparing both Fig.2 and Fig. 4. In addition to that, the
enrichment value increasing, with the decrease in the
maximum enrichment values are higher for whey's
whey volume inside the column (at constant air
yogurt than for that of cheese, due to the higher ability
flowrate). These obtained values for enrichment values
of yogurt whey to generating foam inside the column.
are in a good agreement with those in literature, i.e.,
Figure 5 shows the result of enrichment value for
Zaid and Hosasin,[9], Hossain and Fenton [10]. In their
cheese whey. Here it is interesting to mention that
investigation they got 2-8 enrichment value, within pH
when there is enough self foam generation (in case of
ranges of 5-10 for extracting single protein from a
whey yogurt) the enrichment value will be higher, as it
mixture of water and protein.
can be revealed by comparing both figures 2 and 4,
Both yogurt and cheese whey's experiments
which means self-foam generation will give better
showed that as the height of the whey inside the column
enrichment values. Moreover, when the air flowrate
increases, the proteins concentration in the foamate
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Am. J. Applied Sci., 5 (5): 468-472, 2008

decreases. This is true due to the fact that, as the height
increases the zone available for separation and to be
enriched by reflux will be less. According to these
results, it is better to keep the height as much as lower
than half of the column, to enhance the separation zone
and to keep the gas flow as low as it is possible, say
0.20 l/min.

Fig. 5: The effect of air flowrate on the enrichment
value for cheese whey at constant liquid
holdup

CONCLUSIONS

Separation of protein from both yogurt whey and

Fig. 3: The effect of air flowrate at constant liquid
cheese whey were successfully obtained from whey
holdup on the enrichment value for yogurt
waste.Whey cheese gives less foam during
experimental works, compared to yogurt whey. This
whey
has its effect on the enrichment value. It was noticed

that higher enrichment value was obtained for yogurt
In the case of cheese whey, the results showed that
whey than that of cheese whey. The results showed that
there are less foam generation, even when the air
there is a limited value for air flowrates above of that
flowrate was increasing several times higher from of
no separation could be obtained and this value was
that for yogurt whey. In addition to that, the same value
found equal to 1.85 l/min. Although cheese whey
for
the air flowrate used in
the
yogurt whey's
contains higher protein content in the original sample
experiments was not able to increase the enrichment
compared to yogurt's whey, better protein separation
value for cheese whey. The enrichment value will be
obtained for yogurt whey. Cheese whey generates less
less when the whey volume inside the column is
foam, compared to yogurt this will make bubble foam
higher. This behavior was the same as explained before
separation not suitable to extract protein without adding
for the yogurt whey, adding to that less foam foaming agent, this is due to the high concentration of
generation.
fat in the cheese whey that breaks down foam and
decreases its stability.
As the height decreases, the amount of separated
protein increases, then the efficiency of the foam
separation process increases too. The same was noticed
when the gas flow rate decreases, the amount of
separated proteins increases

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