Delactosed whey (DLW), which has ~24% protein, is a by-product of lactose
production and is mostly used as animal feed. DLW applications can be expanded to
include food products, and its economic value improved by amplifying its protein
functionality. Moderate enzymatic hydrolysis can significantly enhance protein
functionality. It is, therefore, hypothesized that subjecting DLW to enzymatic proteolysis
will lead to enhanced functionality. To amplify and improve the functionality of DLW
via enzymatic hydrolysis, hydrolysis conditions need to be optimized. The infinite
number of possible combinations of factors and their levels to be tested makes the task
quite challenging. Using response surface methodology (RSM), the number of
experimental units necessary to find the optimal point can be tailored depending on the
time and resource constraints of the experimenter.
The first objective was, therefore, to amplify the functional properties of the protein
component of DLW by enzymatic hydrolysis using response surface methodology
(RSM). The second objective was to monitor the functional properties and sensory
quality of beef patties fortified with selected DLW hydrolysates as compared to those
fortified with whey protein isolate (WPI) and whey protein concentrate 34% (WPC 34).
In order to determine the optimal hydrolysis conditions, a Box-Behnken design with 4
independent variables at 3 levels was generated and implemented. The variables chosen,
temperature (x1), enzyme-to-substrate (e/s) ratio (x2), time (x3) and pH (x4), are known to
have the most significant influence on the degree of hydrolysis (DH) and protein
functionality. The design had 27 experimental units that included 3 center points to assess
the pure error. Each experimental unit was run in triplicate and the means of DH and
measured functional properties were recorded as the y responses. The behavior of each
response was explained by a quadratic equation. The effect of the independent variables
on each response was evaluated and tridimensional response plots were generated. The
conditions at which the responses were maximal/optimal were then determined. To
validate the model, experimental data was obtained using the predicted optimized levels. iii
In triplicate, ground beef patties were formulated using selected DLW hydrolysates, with
optimized functionality, non-hydrolyzed DLW, WPC34 or WPI. A control sample was
formulated without the addition of any whey protein ingredient. Cook loss due to losses
in water and fat was assessed. Texture analysis of the cooked patties was done using a
TA-XT2 texture analyzer. Sensory analysis was conducted to determine differences in
various attributes among the different beef patties.
Several response surface models were compared to determine the best fit for the RSM
data collected. The point within the range of experimentation with the highest fitted value
was determined. Using the model with the best fit (high R2 and P ≤ 0.05) for each
response, prediction equations were generated and used to determine optimal hydrolysis
conditions. Within the range tested, the emulsification capacity and activity of the DLW
hydrolysates, produced under optimal conditions, were comparable to, if not greater, than
that of WPI, which is known for its exceptional functionality attributes. The RSM
approach provided an understanding of the effect of each hydrolysis parameter on the DH
and on the assessed emulsification properties. Results highlighted that the extent of hydrolysis had a significant effect on the final functionality. While emulsification
properties were enhanced significantly, hydrolysis of DLW was detrimental to the
Beef patties formulated with hydrolyzed DLW, with optimal emulsification
properties, lost about half as much moisture as the control. The fat loss in the beef patties
formulated with hydrolyzed DLW was about 5 times less than that of the control. The
beef patty formulated with Alcalase hydrolyzed DLW had significantly (P < 0.05) higher
compression force than the control. The functional performance of DLW hydrolysates in
the formulated beef patties was comparable to that of WPI. While instrumental
measurements indicated functional differences, the formulation with hydrolyzed DLW
did not affect the sensory quality of the beef patties.
Results of this work showed, for the first time, that the functionality of the protein
component of DLW can be amplified upon limited and controlled hydrolysis. The tested
DLW hydrolysates can be incorporated into meat products to amplify the functional properties without jeopardizing the overall sensory quality. Therefore, functionally iv
enhanced DLW have a great potential to reduce processing cost by replacing WPI, while
maintaining acceptable quality.
University of Minnesota M.S. thesis. September 2012. Major: Food Science. Advisor: Baraem Ismail. 1 computer file (PDF); xiii, 107 pages, appendices A-G.
Folly, Edem-Elikplim E..
Enhancing the functionality of delactosed whey by enzymatic hydrolysis using Response Surface Methodology Approach (RSM).
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