Sent: November 20, 1998
From: Lee Rawlinson AHG EFAS [SMTP:L.Rawlinson@cefas.co.uk]
To: 'John Castell' <CastellJ@mar.dfo-mpo.gc.ca>
QUESTION:
I am looking to preserve concentrated algae (algal pastes made with a
continuous centrifuge) and have one or two notes on using glycol but
there is precious little detail.
Does anyone know any techniques using glycerol or glycol, or perhaps glycol derivatives such as propylene glycol (food grade)?
I have also heard of the use of a salt brine used by a Bob Engel (?) who had problems with bacteria in a cornmeal slurry; could this be used and if so in what concentrations?
Lee Rawlinson
CEFAS
Fisheries laboratory
Benarth road
Conwy
Wales UK
LL32 8UB
Tel:- +44 (0) 1492 593883
Fax:- +44 (0) 1492 592123
e-mail: l.rawlinson@cefas.co.uk
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COMMENTS 1:
I suggest one avenue might be to check with Gordon Jones of Innovative Aquaculture: InnovativeAqua@compuserve.com
They produce and market concentrated algal pastes.
I will send your request to our live feed server list to see if they have
more information. There are several companies in Japan that market algal pastes or algal concentrates. That might be a good starting place as well.
John Castell
Department of Fisheries and Oceans
Biological Station
St. Andrews, NB E0G 2X0, Canada
Phone (506) 529-5904
Fax (506) 529-5862
E-mail: CastellJ@mar.dfo-mpo.gc.ca
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COMMENTS 2:
I was working with Nano paste few years ago as a possible substitute
for live alga supplement to sea bream larval tanks. We found that a
mixture of 9% food grade propylene glycol + 1% BHT at pH-8.1 added immediately after concentrating at low speed (important to not damage the algae cells) was the best way to preserve the algae. Although it depends on how dry (or wet) is your final paste and more important on your algae species and harvest timing in regard with growth phase, you may expect over 75% survival of Nano after 4-6 months at -20C, but leaching increases significantly after only 2 months. Propylene glycol allows to preserve the algae at -20C without freezing and is a neutral compound that can easily be metabolized into lactic acid. BHT reduces the production of oxidative products of the leaking amino and fatty acids.
Moti
harel@umbi.umd.edu