Pollution Control Implications of Protein
Recovery Systems
RICHARD M. AHLGREN, Manager
Protein Processing Systems
Aqua-Chem, Inc.
Milwaukee, Wisconsin 53201
INTRODUCTION
Human nutrition and food shortages are one of the key elements in many of the
international and social problems facing our world today. Food supplies, together with
energy sources rank near the top of the list in virtually all national and international
problem areas. Still another problem which sometimes becomes subverted to food and
energy issues is that of environmental management and pollution control. Usually the latter
problem, environmental management, is only dealt with openly and considered a real
problem when the first two areas, nutrition and energy, appear to be fully satisfied and
under control. With advanced technology, the answer to one of these major problems often
provides answers or assistance in alleviating the other two.
The world wide deficiency in protein is now estimated to be about nine billion pounds
annually. There is virtually no presently developed single source of protein in the world
which could be tapped to satisfy this entire need. In addition to the probable inability of any
single current production method to yield this quantity of protein, there is also the aspect
that either physiologically or aesthetically, no single protein source is acceptable to all
people. In some cases, physiological difficulties are caused by the ingestion of certain
protein rich foods by people having a natural intolerance to portions of these products. An
example of this is the basic intolerance of some people to milk or milk products. Coupled
with this are the many variations in religious dogma or tenets held by some people so that
certain protein sources are not even considered as viable foods.
A measure of protein utilization in the human body has been adapted. This scale is
known as the Protein Efficiency Ratio or PER. On this scale, protein sources are rated
relative to each other. The generally considered mid-point of the scale is casein derived from
whole milk, which is said to have a protein efficiency ratio of 2.5. Near the top of the scale is
whole egg with a PER of 3.5. Lactalbumin or milk protein ranks just below whole egg at a
PER of 3.2. Fish, whole milk, and beef range between 3.0 and 2.6. Yeast protein and soy
generally fall in the range between 2.4 and 2.0. Oil seeds and grains are considered at the
lower end of the scale, between 1.7 and 1.0.
In addition to the protein efficiency with respect to human nutrition, foods are also
rated with respect to functionality. Functionality is a broad measure of the compatibility or
acceptability of the physical properties of the protein sources themselves or their influence
1036