Biology Reference
In-Depth Information
58% of carrageen, ~31% alginates, and ~11% agar (Bixler and Porse
2011
). The
demand particularly for carrageen could not be met lately mainly due to the
increased demands of the Chinese hydrocolloid industry. Moreover, collective
quantity does not always suffice, since species as well as geographical location
and climate where the seaweeds are grown and the season of harvest determine the
chemical characteristics of the hydrocolloids and their quality. Quality is also
influenced by the extraction methodology (Bixler and Porse
2011
).
Aware of the fact that there is a great variety of chemical compositions and
therefore bioactive properties in the different species of seaweeds Løvstad Holdt
and Kraan (
2011
) supply a wealth of current knowledge on bioactive compounds of
the most important species in 21 tables comprising the various polysaccharides,
proteins, peptides, and amino acids as well as lipids and fatty acids, pigments,
vitamins, iodine, phenolic components, and undesirable substances like heavy
metals: The vast range of biological activities they listed originated from in vitro
investigations up to clinical studies. Most spectacular are the antibacterial and
antiviral activities that may partly be responsible for the records on positive effects
against tumors and HIV. Important beneficial effects for human health lie also in the
reduction of blood cholesterol levels and anti-diabetes and anti-hypertension
effects. In addition to direct pharmaceutical uses of algal ingredients, a high-tech
medical use of alginate as part of a matrix that can carry protein drugs is being
developed. It utilizes the mucoadhesive property of alginate helping to retain the
drugs in the gastrointestinal tract for a longer period, thereby improving drug
bioavailability and effectiveness in the intestine (George and Abraham
2006
).
While the list of beneficial effects of seaweeds and their ingredients on humans is
long, the process of getting them authorized as food or medical items can be as well
(Løvstad Holdt and Kraan
2011
).
22.3.3 Seaweed in Agriculture and Animal Diets
The large amounts of minerals, trace elements, vitamins, and iodine among other
components render seaweeds, particularly the brown ones, a valuable addition not
only to food but also to livestock feed and soil fertilization (lit. in Bartsch et al.
2008
; Craigie
2011
). Some direct or indirect beneficial effects hold for plants as
well as animals of very different classes. An example is antihelmintic properties of
seaweed extracts that can help not only mammals but also plants like tomatoes
which suffer from nematode infestations in their roots (Løvstad Holdt and Kraan
2011
; Craigie
2011
). While commercial seaweed extracts have been available for
60 years, only 1% of the current seaweed industrial production goes into agricul-
tural use, even though according to Craigie (
2011
) “seaweed extracts can modify
plant and animal responses at a fundamental level.” However, the appropriate
utilization of seaweed meal or extracts in agriculture and as feed addition has to
be experimentally secured in advance of extensive use. Craigie (
2011
) reviews the
history of seaweed utilization and the development of extracts and the responses of
