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Background and Objective:
The original
purpose of this project was to develop Hemp Protein Powders and Hemp
Protein Isolates by further processing hemp seed cake or hemp meal,
the byproduct remaining after hemp seed oil extraction. This protein
enriched hemp seed cake naturally contains approximately 31-33% protein,
48% carbohydrates and 7-9% after the cold-press extraction process. The
objective was to develop a method or process by which this protein could
be concentrated into powders (40-60% protein), concentrates (60-90%
protein) or isolates (+90% protein). Hemp protein is potentially a high
value product as it contains significant quantities of 20 amino acids
including all of the essential amino acids.
Procedure
and Project Activities:
Initial laboratory scale work
was completed to determine the optimum extraction pH for the
recovery of the protein from hemp seed
cake, the base raw material. This work was performed at the POS Pilot
Plant in Saskatoon under the direction of Rick Green.
This lab scale work first
involved establishing the optimal pH ranges for producing a protein
powder concentrate by aqueous leaching, ethanol leaching and by enzyme
assisted leaching processes. Three processes and various pH levels were
compared to determine which process produced a protein concentrate
yielding the highest recovery and purity of protein. Extraction at pH
6.5 produced the highest recovery of protein at 89% and a purity of
46.3%.
The second step
of the lab scale work involved producing a protein isolate. The hemp
protein isolate was prepared following a similar process for soybean
protein isolate. From the protein concentrate tests, the optimum
isoelectric pH was determined to be pH 6.5, but the effective alkaline
pH levels for dissolving the proteins needed to be determined. The
optimum extraction pH for the protein purity and yield was determined to
be 64.7% at pH 11.0 producing a protein purity between 92-100%.
Protein powder concentrates and
isolates produced were both spray dried and vacuum dried, after which
amino acid profile analysis was conducted. Comparison tables between
hemp protein powder concentrate and protein isolates to that of soybean
were prepared and evaluated.
These initial lab scale steps produced the following
interim conclusion:
De-fatting of the hemp
flour was required for effective wet processing of the protein
concentrate and isolate. The effect of pH on preparation of hemp
protein concentrate and isolate was determined. Extraction at pH 6.5
produced the highest recovery of protein at 89% and a purity of 46.3%
protein. However, initial milling and sifting tests conducted, produced
a similar protein content simply by air and screen classification of
hemp seed cake. Thus, the preparation of a hemp protein concentrate by
wet processing (i.e. aqueous, ethanol or enzyme assisted aqueous
leaching) may not be practical, nor cost effective.
Hemp protein isolate with a
protein content greater than 92% and protein recovery greater than 64%
was produced using an extraction pH of 11 and precipitation pH of 6.5.
In comparison to soy protein,
the hemp contained a higher level of methionine, lower level of lysine,
and similar levels of other essential amino acids.
The protein concentrates and
isolates were effectively spray dried using an air inlet temperature of
150°C
and outlet temperature of 80°C.
In the next step of the project,
the applicant evaluated the employment of this baseline data collected
during the lab scale work and applying it to a commercial process in a
pilot scale setting. In February 2002, they presented their proposal to
Greg Willie of Bio Processing in Saskatoon. A request for quotation was
made to produce a minimum of 1000 kg of the protein powder concentrate
and several hundred kilos of the protein isolate. The intention was to
use this product for distributing samples to companies worldwide that
had expressed an interest in utilizing these hemp protein derivatives in
their products.
Unfortunately, it became
apparent very quickly that this type of value-added processing would be
extremely cost-prohibitive to pursue further. The cost quoted back to
commercially produce 1000 kgs was over $82.00 per kg and reduced to
$29.00 per kg for volumes in excess of 4500 kgs.
At this point in the research
project, a decision was made to abandon the development of a hemp
protein isolate, and rather focus on the development of a hemp protein
powder or hemp protein concentrate that could be produced utilizing
relatively inexpensive existing processing technologies.
Hemp Oil Canada then directed
research efforts in two directions simultaneously.
The first was to contract with
the University of Manitoba, Food Sciences Department to utilize the
baseline data collected in the initial steps performed at the POS Pilot
Plant and develop a processing method to further de-fat the mechanically
produced protein powder.
The second direction was to join
forces with another hemp food company that was coincidentally
researching the development of a hemp protein powder at the same time.
The purpose of this co-funded work was to identify the best method to
mechanically mill and sift the hemp seed cake into a fine powder with
most of the fiber content removed which would concentrate the protein.
In May 2002, Hemp Oil Canada
contracted with the University of Manitoba, Food Sciences Department
under the direction of Dr. Arnie Hydamaka and Dr. Susan Arntfield to
identify both a processing method and the optimum level of protein
extraction that could be achieved.
A decision was made to utilize a
“food grade” ethanol as the extracting solvent. The purpose of this
process development would be to maximize the final protein content while
minimizing the final fat content. The University of Manitoba conducted 4
different extraction tests on the milled hemp meal. The first test
involved testing various ethanol concentrations; the second test
examined the effect of heat on the extraction; the third test compared
double extractions to single extractions; and the fourth test examined
the optimum extraction time.
The University of Manitoba tests
determined and concluded that using a 95% ethanol as an extracting
solvent in a double solvent extraction process (1 hour + 1 hour), the
fat content of the hemp meal could be reduced to below 1%, thus
concentrating the protein remaining in the powder to greater than 58%.
Further results concluded that only a high concentration of ethanol had
an effect on reducing fat and that introducing heat had little affect on
reducing the fat content.
Also in May 2002, Hemp Oil
Canada joined forces with the hemp food company, formally known as
Ancient Harvest of Vancouver, BC to determine the best method to
mechanically mill and sift the hemp seed cake into a fine powder. The
step of sifting the hemp seed cake would remove most of the shell fiber,
thereby concentrating the protein. This development work was performed
both in BC and with a flour mill manufacturer in Maple Creek, SK. Hemp
Oil Canada agreed to co-fund and participate in this research. In
addition, Hemp Oil Canada separately worked with a number of other mill
and sifting manufacturers to determine optimum processing conditions.
The joint research determined
that modifications to existing flour mills and sifting systems could be
made to optimize the protein content of the hemp powders produced. The
applicant concluded that hemp seed cake could be fine milled down to
particles as small as 120 mesh/124 microns. However, the fibrous shell
of the seed would produce particles no smaller than 60 mesh/246 microns.
Therefore, removal of the shell could be achieved by either further air
classification of the material or sifting over a 60 mesh screen.
Approximately 54% of the material remaining above a 60 mesh screen was
identified as primarily fiber, while 46% of the material through a 60
mesh screen was identified as having a protein content >50%. The
highest test sample result was 53.5%.
Conclusions:
From the work
performed in this research project, the following conclusions were
drawn:
-
Hemp protein concentrates and
isolates can be produced from hemp seed cake. However the production
of such concentrates is both cost prohibitive and employs the
introduction of solvents and heat that may damage the proteins and
amino acid assay. In addition, the introduction of such solvents
would not be considered “natural, organic or friendly” to today’s
conscious consumers.
-
Hemp protein powder could be
further concentrated utilizing a 95% ethanol solution in a double
extraction process. However, the maximum concentration of protein
achieved in the resulting powder was only 58%. As with the production
of a concentrate or isolate, this value-added step may not be
considered “natural, organic or friendly” to today’s conscious
consumers. Although the applicant would recommend further research be
conducted in this direction, it may be also a cost prohibitive step
considering the high cost of this process and equipment infrastructure
required, as well as the relatively small gain of protein.
-
The custom milling and sifting
of hemp seed cake into a hemp protein powder would appear to be the
most cost effective, low heat and non-chemical process to employ.
This method not only insures the presence of live active enzymes, but
it is also a natural process which can be “certified organic” which is
trend now growing tremendously in the marketplace. Of the three
processing methods researched, this process offers the most cost
effective entry in terms of processing infrastructure. It provides a
relatively high protein content at the lowest cost of production.
Since completing this research
project, Hemp Oil Canada has purchased the necessary flour milling and
sifting equipment needed to produce +50% protein content powders which
are already having a tremendous impact on their sales in the
marketplace.
Consumers are looking for
natural, organic, plant-based sources of protein to supplement their
diet and the hemp protein powder fills the need very nicely.
Hemp Oil Canada is now “private
labeling” this product for no less than 4 other hemp food companies at
this time.
Acknowledgements:
This project was made possible
due to the funding from the Governments of Manitoba and Canada through
the Canada-Manitoba Agri-Food Research and Development Initiative
(ARDI).
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