Re: Reducing Water Activity in Caviar

From: Ted Labuza (tplabuza@umn.edu)
Date: Fri Aug 24 2007 - 14:57:31 PDT

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    -- 
Dr. Ted Labuza  
Morse Alumni Distinguished Teaching Professor of Food Science and
Engineering
Department of Food Science and Nutrition Univ. of Minnesota  Rm. 136 A 1354
Eckles Ave. St Paul 55108
email - tplabuza@umn.edu ext Msg  6513072985@mobile.mycingular.com  Cell
651-307-2985
Office ( 612-624-9701            UM 7  fax 612-625-5272          NFNC 7
Fax 661-483-3302
web     http://www.ardilla.umn.edu/Ted_Labuza

    From: Ted Labuza <tplabuza@umn.edu>
Date: Thu, 23 Aug 2007 09:16:49 -0500
To: SPINALI <spinali@seafoodhaccp.com>
Conversation: Reducing Water Activity in Caviar
Subject: Re: Reducing Water Activity in Caviar

    Maltodextrin would have little effect. Water activity lowering in solution
is based on Raoult's law where

    aw (a is small case and w is subscript) = moles of water/(mole water + moles
solute)

    For 1000 g water (155.53 moles) adding in 500 g or maltodextrin

    Maltodextrins have a log normal distribution of molecular weight. Using the
average which is ~ 100,000
500 g = 0.005 moles

    aw = (55.53/55.535)=0.999

    Essentially no effect
Your best bet would be things like glycerol or maltitol but they will impart
undesirable flavor
To achieve  0.97 you need to substitute in the above equation for aw (0.97)

    The answer is 1.71 moles per Kg of water

    So if in 100 g of caviar you have 70 g water you need to add 0.07 kg water x
1.7 mole/kg water = 0.12 moles of solute

    For a 200 MW substance then you are adding 200 x 0.12 = 24 g of solute per
70 g water or a 25.5 % (w/weight total) solution. This would probably be
unacceptable

    Salt as NaCl (MW = 858.4) is more effective due to lower MW and the
dissociation into 2 moles of solute ie Na+ and Cl- so for 70 g water you
have 
aw=0.97=(70/18.01)/((70/18.01)+2 n)) = 3.89/(3.89+2n)

    So n = 0.058 moles = 3.42 g salt   which is 3.42/(73.42) = 4.5 % salt
solution, yes very salty but inhibitory to many spoilage organisms but would
allow growth of Staph, botulinum and some Listeria species ie it is still a
PHF.

    -- 
Dr. Ted Labuza  
Morse Alumni Distinguished Teaching Professor of Food Science and
Engineering
Department of Food Science and Nutrition Univ. of Minnesota  Rm. 136 A 1354
Eckles Ave. St Paul 55108
email - tplabuza@umn.edu ext Msg  6513072985@mobile.mycingular.com  Cell
651-307-2985
Office ( 612-624-9701            UM 7  fax 612-625-5272          NFNC 7
Fax 661-483-3302
web     http://www.ardilla.umn.edu/Ted_Labuza

    From: SPINALI <spinali@seafoodhaccp.com>
Date: Wed, 22 Aug 2007 21:30:35 -0400
To: <owner-seafood@ucdavis.edu>, <seafood@ucdavis.edu>,
<spinali@seafoodhaccp.com>
Conversation: Reducing Water Activity in Caviar
Subject: Reducing Water Activity in Caviar

    Dear All:

    Hope this is the right address to post a message/question.  We are looking
for an inexpensive but effective way to reduce the water activity in
spoonbill roe to an acceptable level for caviar that will be kept under
refrigeration.  I believe the water activity should be 0.97 or less.
Salting the product to acceptable levels creates an unpalatable product.
Will maltodextrin work?  Any suggestions?

    All advice would be appreciated.

    Thank you,
-- 
BILL SPINALI
FDA Consulting Services, LLC
Tel: 978-283-1195
eFax: 801-684-7155
Cell: 617-308-7611
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