Introduction
Shrimp are captured, processed, and traded by more countries
than any other seafood. They are among the most valuable
seafood products and are consumed all over the world. In
the leading industrialized nations the taste for shrimp in various
forms and species is still growing. Thermal processing is one
of the most effective means of preserving food (Karel and others
1975) and canned shrimps, which helps in preservation, has very
good market demand. Various researchers (Hu and others 1955;
Goldfarb 1970;Ravishankarandothers 2002;Binduandothers 2004)
have proven the technical and commercial feasibilities of using
retortable pouches for thermal processing. The advantages of retortable
pouches include shelf stability, lower weight, and storage
space, ease of opening and preparation, and reduced heat exposure
resulting in improved quality. Pouches in general use today consist
of 3 film layers such as polyester, aluminum foil, and cast polypropylene
(Griffin 1987).
Reduction of heating time using pouches has been reported by a
number of workers (Lampi 1977; Chia and others 1983;Durance and
Collins 1991). Chia and others (1983) reported 34%, 32%, and 37%
lessprocessingtimeforpouchedrainbowtrout, pollock,andshrimp,
respectively, compared to canned products. Durance and Collins
(1991) reported a 48% reduction for chum salmon in pouches compared
with cans. Ali and others (2005a) reported a reduction in processing
time with increased rotation for thermally processed tuna
in oil in retort pouches.
Various researchers have compared the quality attributes of
canned and pouched products. Heidelbaugh and Karel (1970) reported
no significant differences in sensory scores for cranberry
sauce and vegetables with bacon processed in metal cans or plastic
films and laminates of polyester, aluminum foil, and polyethylene.
Dymit (1973) reported that after 8 y, shrimp in retort pouches weresuperior in flavor and color to canned products. Chen and George
(1981) showed that green beans processed in pouches had better
flavor, texture, and overall acceptability than when processed in a
can but the color of the canned beans was preferred. Durance and
Collins (1991) reported significantly less off-flavor and greater acceptance
of chum salmon in retort pouches than cans. Chia and
others (1983) reported that the pouched products were firmer in
texture and lighter in color. Gopal and others (2001) reported that
mackerel fish curry processed in retortable pouches had a shelf life
of not less than 12 mo at ambient temperature. One of the main
features in appreciating seafood is the texture (Cheret and others
2005). The appearance and the odor are also very important for
consumers. Sanchez-Brambila and others (2002) reported the sensory
characteristics and instrumental texture attributes of papain
treated abalones. The texture profile analysis (TPA), which measures
the compression force of a probe and the related textural parameters
of a test food during 2 cycles of deformation of various
foodstuffs including fruits, vegetables, bakery, meat products, and
seafood, specifically retorted products, has been reported (Panifield
and Campbell 1990; Durance and Collins 1991; Sanchez-Brambila
and others 2002; Caine and others 2003). Cheret and others (2005)
reported that high pressure treatment improved the textural quality
of sea bass. Ali and others (2005b) showed an improved texture of
canned sardine in oil in pouches compared to cans.
“Kuruma” is a delicious popular curry product best known in India.
It can be prepared with vegetables, chicken, mutton, fish, and
shrimp.Thepresentworkwasundertaken with themainobjective of
comparing the relative processing time of Shrimp Kuruma, a value
added product, in retortable pouches, and aluminum cans and the
effect of containers on the proximate composition and quality parameters,
including sensory and instrumental texture quality.
Materials and Methods
Shrimp
Indian white shrimp (Feneropenaeus indicus, previously Penaeus
indicus) were collected from a commercial fish-landing center inCochin, India. The average size of the shrimp was 125 to 130 mm
with counts of 5 to 6 shrimp per 100 g. The shrimp were kept in
high-density polyethylene boxes and transported in ice to the laboratory.
Upon arrival, shrimp were washed with chilled water and
hand peeled and deveined. Shrimp were precooked in 4% brine for
4 min at 100 ± 2 ◦C, drained and cooled under a fan.
Kuruma preparation
The recipe for the Kuruma preparation is given in Table 1.
Chilli powder, coriander powder, and turmeric powder were gently
warmed and blended with 50 mL water. Half of the chopped onion
was fried and blended using a mixer grinder (Sumeet Asia Kechen
Machines, 550Watts, Sumeet Research andHoldings Ltd., Chennai,
India). The other half of the onion, green chilli, and ginger were
fried in refined sunflower oil, then mixed with the fried paste of
onion and powdered chilli-coriander-turmeric mixture. Tomatoes
were cut into small pieces, blended in a mixer grinder, and added to
the above paste and cooked gently with salt.
Thermal processing
Retortable pouches, 16 cm×20 cm made with 12.5 μmpolyester
(outer layer), 12.5 μmaluminum foil (middle layer), and 85 μmcast
polypropylene (inner layer) (M.H. Packaging, Ahmedabad, India)
and aluminum cans, 301 × 206 or 77 mm × 60 mm, (diameter
× height) (8 oz or 226 g) (M/s. Klass Engg. Pvt. Ltd., Bangalore,
India) were filled with 128 g precooked shrimp and 68 g Kuruma
to maintain equal pack weights of 196 g. A thermocouple (Ellab
SSA- 12050-G700-TS stainless steel, Ellab Co. Reodovre, Denmark)
tip was immobilized in the geometric center of both canned and
pouched product. Residual air was removed by steam exhausting
and the sealed containers were processed in an over pressure autoclave
(Model No. 5682, John Fraser and Sons Ltd, Newcastle-upon-
Tyne, UK) at 121.1 ◦C. Cold point temperature was monitored in 3
separate containers using a data recorder (EllabCFT9008,Reodovre,
Denmark). Initially, the process was done at 3 different lethality (F0)
values, that is, 7.0, 8.0, and 9.0, separately for cans and pouches to
standardize the optimum process parameters. The products processed
at lethality 8.0 in both cans and pouches were found suitable
according to the sensory panels. The F0 8.0 was then used in
the further study. The process time was calculated by the formula
method of Stumbo (1973). The cook value, which is a measure of
heat treatment with respect to nutrient degradation and textural
changes that occur during processing, was determined by measuring
the extent of cooking and nutritional loss during processing in
a manner similar to the D value, except that the reference temperature
is 100 ◦C instead of 121 ◦C, and z value is 33 ◦C, which
is required for the denaturation of thiamine (Ranganna 2000). After
processing, the samples were kept at ambient temperature for
2 wk for conditioning. After conditioning, 5 canned and 5 pouched
samples were taken for analysis. The shrimp were separated from
Table 1 --- Ingredients for Shrimp Kuruma