And to augment what Peter is saying, what type of salt is being used? Some
try to use cheaper lower-quality salt where the impurities are too high,
meaning that heavy metals can promote rancitity. Only a good food-grade
99.9% pure salt should be used.
Also, what is the oxygen transferrance data on the packaging film? It
should be very low.
Paul G. Taylor
Evergreen Food Ingredients
2210 Black Lake Blvd. S.W.
Olympia, WA 98512-5604 U.S.A.
Phone: (360)754-1718; Fax: (360)705-1359
www.everfoodingr.com (under construction)
E-mail: pault@everfoodingr.com
----- Original Message -----
From: "P Howgate" <phowgate@rsc.co.uk>
To: <richard@fishonline.co.uk>; "seafood" <seafood@ucdavis.edu>
Sent: Thursday, December 19, 2002 5:55 AM
Subject: Re: vacuum packing to prevent oxidation
> Dear Richard
>
> I suppose the first question to ask is how does the client know the
product
> is oxidising? If the pack is truly a vacuum pack, where is the oxygen
coming
> from to cause oxidation? If it is a chemically induced oxidation involving
> an oxygen-containing compound rather than gaseous oxygen, then I can not
> visualise a packaging that will prevent the oxidation. I can not see how a
> gas-flushed package containing 40% oxygen can be better than
> vacuum-packaging in preventing oxidation. Usually products produced by
> pickle salting, where the product is maintained below the surface of the
> brine, does not develop oxidative rancidity during the pickling stage; I
> note you report that your client's product does develop rancidity in
> 'traditional wooden tubs' and I wonder if the problem resides in the
salting
> process.
>
> Are you sure your client really is measuring oxidation rather than a
> microbiological spoilage effect? 14% salt content in the water phase is
not
> very high, Aw about 0.93, and not sufficient to inhibit microbiological
> spoilage by salt-tolerant microorganisms.
>
> Peter Howgate
>
>
> ----- Original Message -----
> From: "Richard Chivers" <richardchivers@btconnect.com>
> To: "seafood" <seafood@ucdavis.edu>
> Sent: Thursday, December 19, 2002 12:00 PM
> Subject: vacuum packing to prevent oxidation
>
>
> >
> > A client of mine produces a pilchard product with a salt content in the
> > water phase of 14%, either whole or in fillets. He wishes to pack these
> in
> > a vacuum pack that will prevent oxidation. What he has found is that
> > regardless of vacuum packing in the normal manner, light and heat will
> still
> > cause oxidation.
> >
> > He is trying gas flushing with 60% nitrogen and 40% oxygen in pouches
that
> > comply with the standard Din 53380 Part 3 . The product is to last for
up
> > to 4 months at chilled temperatures and then one month at ambient. In
> > traditional wooden tubs the product will do this although rancidity does
> > develop.
> >
> > Can anyone advise on a gas mix or pouch that would maintain quality by
> > reducing the rate of oxidation in this product.
> >
> > Richard Chivers
> >
> >
> >
>
This archive was generated by hypermail 2b29 : Thu Dec 19 2002 - 11:12:05 PST