Process standardization and shelf- life evaluation of instant rice based meal
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Date
2021
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Abstract
The present study entitled “Process standardization and shelf life evaluation
of Instant rice based meal” was carried out with the objective to standardize the processing
conditions of the ingredients of the developed instant rice based meal, to develop for the
improvement of the formulation using different levels of the developed meal ingredients, to
assess the reconstitution and organoleptic property of the best selected instant rice based meal
and to evaluate the shelf life of the selected formulation using different packaging materials.
The study was carried out in the Food Science laboratory of the Department of Food Science
and Nutrition, Post Harvest Technology Laboratory of the Department of Horticulture,
Nanotechnology Laboratory in the Department of Plant Pathology, Assam Agricultural
University, Jorhat during 2016-2019. The raw materials were procured from the local market
of Jorhat district and Horticulture farm, Assam Agricultural University, Jorhat. To develop
the instant rice based meal formulations, precooked dehydrated ingredients were used.
Initially a base meal (35% rice, 25% pulses, 20% vegetables, 5% RBO, 12% spices and
condiments) was prepared by combining cereal, pulses, vegetables, spices and condiments
and from the Base meal three formulations were developed and standardized viz.,
Formulation I (30% rice, 28% pulses, 24% vegetables, 5% RBO, 11% spices and
condiments), Formulation II (30% rice, 29% pulses, 23% vegetables, 5% RBO, 11% spices
and condiments) and Formulation III (30% rice, 30% pulses, 22% vegetables, 5% RBO, 11%
spices and condiments) by changing the proportion of ingredients used in base meal and by
incorporating other new ingredients. All the ingredients were individually processed by
microwave cooking + blanching (MCB) and pressure cooking + blanching (PCB) and then
dried at different temperatures. Nutrient analysis was done following the standard methods
and acceptability trial was conducted using 9 point hedonic scale by semi-trained panelist.
Process standardization for all the ingredients used in the formulation of instant rice based
meal was done by trial and error method following the standard procedures. According to the
acceptability score, it was found that Formulation III (PCB) had scored the highest score in
terms of flavour (7.90±0.13), taste (8.00±0.07), texture (8.01±0.10) and overall acceptability
(8.15±0.12) by the base meal (PCB) i.e., 7.78±0.12, 7.78±0.15, 7.70±0.11 and 7.90±0.09 for
flavour, taste, texture and overall acceptability respectively. Formulation I (PCB) was
judged with the score of 8.10±0.15 followed by Formulation II (PCB) i.e., 7.95±0.18 in terms
of overall acceptability. Among the formulations processed by microwave cooking +
blanching, Formulation III was judged best with the highest overall acceptability score of
8.26±0.20, followed by Formulation I (8.10±0.17), Base meal (8.05±0.19), and Formulation
II (7.90±0.18). The results showed that highest acceptability was in Formulation III (MCB),
whereas lowest acceptability was recorded in Formulation II (MCB). The instant meal
prepared from pressure cooked + blanched (PCB) ingredients showed that the moisture
content of Base meal, Formulation I, Formulation II and Formulation III and were not
statistically different (p<0.05) from each other. The results of the protein content of the
instant rice based meal formulations prepared by using microwave cooked + blanched (MCB)
and pressure cooked + blanched (PCB) ingredients were found to be in the range of
22.63±0.23g/100g (Base meal) to 26.77±0.17g/100g (Formulation III) and 21.54±0.21g/100g
(Base meal) to 25.19±0.16g/100g (Formulation III) respectively and were significantly
different at p<0.05. The total mineral, crude fibre and carbohydrate content of the instant rice
based meal formulations prepared by using microwave cooked + blanched (MCB) were
found to be significantly higher (p<0.05) as compared to the instant formulations prepared
from pressure cooked + blanched (PCB) ingredients. But the mineral content did not vary
significantly (p<0.05) between the instant rice based meal formulations prepared by using
microwave cooked + blanched (MCB) and pressure cooked + blanched (PCB) ingredients
and this may be because of the fact that minerals like iron, calcium and phosphorus are heat
stable therefore cooking method and temperature do not appear to reduce the quantity or
availability of this mineral but they were found to differ significantly (p<0.05) within the
formulations
The best selected formulation on the basis of sensory scores and nutrient
composition i.e., Formulation III was then vacuum packed in two packaging material i.e.,
aluminium laminated pouch and HDPE pouch of 200 gauge and was further subjected to
storage studies i.e., sensory evaluation, nutrient composition, peroxide vale, free fatty acid
value and total microbial count at a regular interval of 2 months for a period of 6 months.
With the advancement in storage period, nutrient content, peroxide value, free fatty acid
value and total microbial count increased significantly (p<0.05) and was however within the
permissible limit indicating acceptability of the formulations upto a period of 6 months.
Highest peroxide value of Formulation III was observed in HDPE pouch starting from 0 day
till 6 months i.e., from 1.81±0.26 meq O2/kg (0 day) to 4.42±0.12 meq O2/kg (6months) in
MCB and from 1.87±0.27 meq O2/kg (0 day) which gradually increased to 4.84±0.32 meq
O2/kg after 6months of storage.. The free fatty acid (FFA) content of Formulation III (MCB)
stored in the aluminium laminated pouch was in the range of 0.18±0.04mg/100g at 0 day to
3.45±0.12mg/100g after 6 months of storage and that stored in HDPE pouch showed a
gradual increase from 0.18±0.04g/100g at 0 day and finally to 3.79±0.14g/100g at 6 month across storage. The FFA content of Formulation III (PCB) stored in the aluminium laminated pouch increased from an initial value of 0.18±0.03mg/100g at 0 day to a final value of 3.40±0.12mg/100g at 6 month while the Formulation III stored in HDPE pouch increased significantly (p<0.05) from 0.18±0.04mg/100g in 0 day to 3.82±0.26 mg/100g in 6 months. Statistically, it was observed that a significant decrease (p<0.05) in the FFA content was observed in the Formulation III packed and stored in aluminium laminated pouch when compared to the Formulation III stored in HDPE pouch. The total microbial count of the formulations significantly increased (p<0.05) with the increase in the period of storage. The results of total microbial count of Formulation III (MCB) stored in the aluminium laminated pouch and HDPE pouch increased significantly (p<0.05) from 1.72×103cfu/g (2 months) to 4.02×103cfu/g (6 months) and 1.90×103cfu/g to 5.14×103cfu/g respectively. The total microbial count of the Formulation III (PCB) stored in aluminium laminated pouch and HDPE pouch increased significantly (p<0.05) with the advancement of storage days from 1.84×103cfu/g at 2 months to 4.21×103cfu/g at 6months and 2.12×103cfu/g at 2months to 5.38×103cfu/g at 6months of storage respectively. Thus, it can be concluded that microwave processed Formulation III packed and stored in aluminium laminated pouch is the best packaging material for storing instant rice based meal due to its barrier function against the migration of moisture, oxygen and other gases.