A more accurate method to evaluate the quality of
proteins is the determination of the protein efficiency
ratio (PER), expressed in terms of weight gain per
unit of protein consumed by the test animal in shortterm
feeding trials. However, still more specific nitrogen
balance methods can be applied to evaluate
the nutritive quality of a protein. One of these principles
is the estimation of the biological value (BV),
which is a measure of nitrogen retained for growth or
maintenance. Another parameter, which reflects the quality of a
protein, is the digestibility coefficient (DC). Finally, the
net protein utilization (NPU) – equivalent to the
calculation BV×DC – is a measure both of the
digestibility of the protein and the biological value of
the amino acids absorbed from the food. Selected data of
such metabolic studies are summarized in Table 3.
The cellulosic cell wall, which represents about 10%
of the algal dry matter, poses a serious problem in
digesting/utilizing the algal biomass, since it is not
digestible for humans and other non-ruminants. Hence,
effective treatments are necessary to disrupt the cell wall
to make the protein and other constituents accessible for
digestive enzymes. Several authors have studied the
effect of different post-harvesting treatments on the
digestibility of various algal species by evaluating the
PER of the treated biomass, demonstrating the important
role of proper processing the algal biomass (Table 3).
A more accurate method to evaluate the quality ofproteins is the determination of the protein efficiencyratio (PER), expressed in terms of weight gain perunit of protein consumed by the test animal in shorttermfeeding trials. However, still more specific nitrogenbalance methods can be applied to evaluatethe nutritive quality of a protein. One of these principlesis the estimation of the biological value (BV),which is a measure of nitrogen retained for growth ormaintenance. Another parameter, which reflects the quality of aprotein, is the digestibility coefficient (DC). Finally, thenet protein utilization (NPU) – equivalent to thecalculation BV×DC – is a measure both of thedigestibility of the protein and the biological value ofthe amino acids absorbed from the food. Selected data ofsuch metabolic studies are summarized in Table 3.The cellulosic cell wall, which represents about 10%of the algal dry matter, poses a serious problem indigesting/utilizing the algal biomass, since it is notdigestible for humans and other non-ruminants. Hence,effective treatments are necessary to disrupt the cell wallto make the protein and other constituents accessible fordigestive enzymes. Several authors have studied theeffect of different post-harvesting treatments on thedigestibility of various algal species by evaluating thePER of the treated biomass, demonstrating the importantrole of proper processing the algal biomass (Table 3).
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