2.3. Study design
The present work was specifically designed to study the effects
of freezing and modified atmosphere packaging (MAP) (100% N2
and 50% N2–50% CO2) compared to vacuum packaging and conventional
method of sulphite (SUL) treatment on the melanosis and
selected chemical qualities of Giant Red Shrimp (GRS) (A. foliacea)
during 12-month period. Choosing the abovementioned was
necessitated by our quest for an alternative to the chemical
approach of sulphite treatment commonly/traditionally used by
the fishery sector. In this context, the commonly/traditionally used
sulphite treatment performs the function of control because it is
the basis of comparison to the other alternative treatments. Well
thought through also is the choice of adapting 100% N2 and 50%
N2 + 50% CO2, which emanated from the biochemical reactions that
foundationally underpin the enzymatic production actuating theformation of black spot of shrimp. In fact, it is to authors’ comprehension
that given the important role oxygen plays in this reaction,
removing the oxygen from this reaction and replacing it on one
hand with only inert gas, and on the other, with gas mixture containing
inert + another acidifying-enhancing gas, would cumulatively
demonstrate improved ‘food technovation’. For emphasis,
the investigated characteristic qualities involved proximal and
gas compositions, melanosis scoring, chemical parameters of pH,
TVB, TBA as well as FAAs. A total of 40 kg of shrimp that were
divided into four lots sufficed for the study. Each lot apportioned
equally into barrier bags that contained about 800 g of GRS samples.
Immediately on-board, GRS samples were quickly processed.
Specifically, whereas prior to packaging 100% N2 MAP and vacuum
packaged samples was subject to blast freezing (35 C), samples
of 50% N2 + 50% CO2 MAP underwent treatment prior to blast freezing.
This approach was selected to allow for CO2 dissolution at
water phase (Devlieghere, Debevere, & Van Impe, 1998) of the
GRS flesh. Essentially, experimental/laboratory analyses commenced
from day 3 after harvest of GRS samples. Prior to all analytical
tests, the shrimp were beheaded, peeled and deveined. In
most cases, experimental/laboratory analyses were regularly
implemented every two months during the 12-month period,
which afforded between 5 and 7 data points of outcomes of storage
measurements of tested parameters against storage time. Unless
otherwise indicated, analyses were repeated three times and independently
per treatment using different GRS samples. All chemicals
and reagents employed are of analytical grade.