To inquest a pertinent technology of preservation seasonal (summer, autumn, winter) nutritive values, effects of potassium sorbate, gamma radiation and their combinations preserved at low temperature on sensory, chemical and microbial properties of freshwater prawn (Macrobrachium rosenbergii, de Man-1879) as well as isolation and identification of associated micro-flora with their sensitivity to potassium sorbate and gamma radiation were investigated during February 2003 to April 2004. Nutritive analysis marked seasonal and body-part variations in moisture, protein, lipid, ash, calcium and phosphorus contents i.e., summer, autumn and winter as 80.07%, 80.37%, 76.99%; 19.20%, 18.03%, 21.30%; 1.23%, 1.07%, 2.99%; 1.48%, 2.00%, 1.21%; 0.19%, 0.21%, 0.14% and 0.10%, 0.08% & 0.10% in edible-part while 77.27%, 76.27%, 73.34%; 16.45%, 17.03%, 19.79%; 1.40%, 1.02%, 4.33%; 6.60%, 7.33%, 6.25%; 2.24%, 2.78%, 1.67% and 0.17%, 0.15% & 0.21% in head-on respectively.
Quality appraisal of treated (potassium sorbate-2%, gamma radiation-2kGy and their combination) and preserved (00C and 40C) samples were done by organoleptic, chemical and microbial evaluation at an interval of 7 days. The shelf life of freshwater prawn at 40C was 14-21 days which was extended to 21-28 days at 00C. Maximum shelf-life (28 days) was found in combined treated prawn that was stored at 00C.
Associated micro-flora were isolated and identified based on their cultural, microscopic, biochemical & physiological characteristics. Among 30 bacterial strains – thirteen (40.33%) were collected from control, nine (30%) from chemical treated, five (16.67%) from radiation treated and three (10%) from combined treated samples. Total 9 bacterial species were identified in which Staphylococcus aureus (23.33%), Bacillus subtilis (20.33%), Micrococcus varians (16.67%) and Escherichia coli (13.33%) were frequent species. Among 10 mould strains – seven (70.00%) were collected from control, three (30.00%) from radiation treated while no colonies were found from chemical and combined treated samples. Total 4 genus of moulds were identified in which Aspergillus (40.00%) was dominant. Potassium sorbate (0, 1, 2, 3, 4 & 5 %) and gamma radiation (0, 2, 4, 6, 8 & 10 kGy) were applied for the sensitivity on identified bacterial species. Staphylococcus aureus, Bacillus subtilis, Micrococcus varians & Escherichia coli were completely eliminated at 4, 5, 3 & 4 % potassium sorbate and 6, 8, 4 & 6 kG gamma radiation doses.
Table of Contents
1. Introduction
1.1 General introduction
1.2 Fundamentals of fish biochemistry
1.3 Contamination of fish and fish products
1.4 Spoilage of fish and fishery products
1.5 Fundamentals of fish preservation
1.5.4. Preservation by combined process
1.6 Freshwater prawn: General aspects
1.7 Aims of present study
1.8 Objectives of present study
2. Review of literature
2.1 Proximate composition of fish and fish products
2.2 Fish preservation by low temperature, chemicals and radiation
2.3 Sensory, chemical and microbial changes of fishes
2.4 Micro-flora associated with fish & fishery products
2.5 Sensitivity to potassium sorbate
2.6. Sensitivity to gamma radiation
3. Materials & methods
3.1 Research affiliations and study periods
3.2 Proximate compositions and mineral contents
3.2.1 Proximate compositions:
3.2.1.1 Determination of moisture content
3.2.1.2 Determination of protein content
3.2.1.3 Determination of fat content
3.2.1.4 Determination of ash content
3.2.2 Mineral contents
3.2.2.1 Determination of calcium content
3.2.2.2 Determination of phosphorus content
3.3 Preservation by combined treatment
3.3.1 Sample collection and sample preparation
3.3.2 Freshness estimation of preserved freshwater prawns
3.4 Isolation and identification of micro-flora
3.5 Chemical and radiation sensitivity of micro-flora
3.6 Statistical analyses
4. Results
4.1 Seasonal proximate compositions and mineral contents
4.2 Quality assessment of preserved freshwater prawn
4.3 Isolation and identification of bacterial flora
4.4 Isolation and identification of mould-flora
4.5 Radiation and chemical sensitivity of micro-flora
5. Discussion
5.1 Seasonal proximate compositions and mineral contents
5.2 Quality assessment of freshwater prawn
5.3 Isolation and identification of micro-flora
5.4 Sensitivity of potassium sorbate and gamma radiation
6. Conclusion
Research Goals and Focus Areas
The primary objective of this research is to investigate effective preservation technologies for Macrobrachium rosenbergii (giant freshwater prawn) to mitigate post-harvest losses and maintain nutritional quality. The study evaluates seasonal variations in nutritional composition and assesses the efficacy of combined preservation methods using low temperature, potassium sorbate, and gamma radiation to extend shelf life and control microbial spoilage.
- Seasonal assessment of proximate nutritive values (moisture, protein, lipid, ash, calcium, phosphorus).
- Evaluation of shelf-life extension using potassium sorbate and gamma radiation at different low temperatures.
- Isolation and identification of bacterial and mould micro-flora associated with freshwater prawns.
- Determination of the sensitivity of major spoilage-causing micro-flora to chemical and radiation treatments.
Excerpt from the Book
1.1 GENERAL INTRODUCTION
As a riverine deltaic country Bangladesh with its warm tropical climate is supremely located and offers an enormous reserve of fresh water, brackish water and marine water fishes as well as the prawns and shrimps. Bangladesh has 0.33 million hectors of inland water and 480 km coastline. During 2000-01 fiscal year about 1.61 million metric ton of fish including prawns and shrimps were produced from different sources (Choudhury, 2001). Bangladesh earns a lot of foreign currency in every year through the export of fish and fishery products that contribute about 5.14% of total export earnings (BBS, 2002) from which 85% of this earning coming from prawns and shrimps (Choudhury, 2001). Bangladesh is exporting frozen shrimps to about 30 countries of the world of which USA, Japan, Belgium, UK, Netherlands and Germany are the most foremost buying countries. Bangladesh offers scientific process and unique combination of natural resources and export friendly infrastructure, thereby making country’s fisheries items genuinely popular all over the world, due to their original taste of the products.
Bangladesh is one of richest country in the world in fresh water fish diversity (Shafi and Quddus, 1982). Fisheries sector plays an imperative role in the economic maturity of Bangladesh contributing about 5.5% of the countries GDP during 2000 – 01 fiscal years (Choudhury, 2001). This sector also acts an important role in rural employment and poverty alleviation. About 8% people of our country are directly or indirectly dependent on fish and fisheries (Islam, 1995). Fish and fishery products have got their supremacy to human consumption for its excellent protein source. About 63% animal proteins come from fish alone (Choudhury, 2001). Supply of fish was 32.8 g out of 57 g protein per person per day in our country (Ali, 1970). It has reported that the daily intake of our protein per person in Bangladesh is around 7-9 g which is 32% of the normal commitment for an adult which indicate there is massive protein deficiency (Haque, 1974).
Summary of Chapters
1. Introduction: Provides background on the fisheries industry in Bangladesh, the nutritional importance of freshwater prawns, and the urgent need for effective preservation technologies.
2. Review of literature: Compiles existing research on the biochemical composition of aquatic products, preservation techniques, and the associated microbial flora.
3. Materials & methods: Outlines the systematic procedures used for analyzing proximate composition, conducting microbial analysis, and performing sensitivity tests for chemical and radiation treatments.
4. Results: Presents detailed data on the seasonal variations of nutritional components and the outcomes of quality assessment and microbial isolation experiments.
5. Discussion: Evaluates the experimental findings, compares them with previous studies, and discusses the implications for preservation and quality control.
6. Conclusion: Synthesizes the research findings, confirming the superiority of combined preservation treatments for extending the shelf life and safety of freshwater prawns.
Keywords
nutritive values, low temperature, potassium sorbate, gamma radiation, freshwater prawn, Macrobrachium rosenbergii, bacterial-flora, mould-flora, shelf-life, food preservation, TVB-N, TMA-N, quality assessment, fisheries, Bangladesh
Frequently Asked Questions
What is the primary scope of this research?
The research focuses on preserving Macrobrachium rosenbergii (giant freshwater prawn) in Bangladesh using a combined approach of low-temperature storage, potassium sorbate, and gamma radiation to prevent spoilage and maintain nutritional quality.
What are the key themes explored in this study?
The study centers on three main pillars: evaluating seasonal nutritive value, identifying and controlling spoilage-causing micro-flora, and determining the effectiveness of chemical and radiation treatments for shelf-life extension.
What is the core objective or research question?
The objective is to establish a pertinent preservation technology that can successfully reduce post-harvest losses and enhance the safety and quality of freshwater prawns for consumer use.
Which scientific methodologies were employed?
The study utilized standard chemical analysis methods (Micro-Kjeldahl for protein, solvent extraction for fat, incineration for ash) and microbiological assessments, including pour plating for bacterial counts and spread plating for mould counts, alongside statistical analysis using ANOVA and Pearson correlations.
What topics are covered in the main body of the work?
The work details the seasonal proximate analysis, experimental preservation treatments at 0°C and 4°C, identification of various bacterial and mould species, and the determination of their specific sensitivity thresholds to potassium sorbate and gamma irradiation.
Which keywords characterize this work?
The work is characterized by terms such as Macrobrachium rosenbergii, gamma radiation, potassium sorbate, microbial spoilage, shelf-life, proximate composition, and cold storage.
What was the observed effect of combined treatment on shelf life?
The study found that the combination of 2% potassium sorbate and 2 kGy gamma radiation, stored at 0°C, provided the maximum shelf-life extension, keeping the prawns in an acceptable condition for up to 28 days.
How did bacterial and mould populations respond to radiation?
Bacterial and mould populations showed significant sensitivity to gamma radiation; specifically, higher doses effectively inhibited or eliminated major spoilage organisms, with the study determining specific dose requirements (e.g., 8 kGy for total elimination of Bacillus subtilis).
- Quote paper
- Mohammad Abdul Salam (Author), 2004, Effect of Preservation Methods on Giant Freshwater Prawn, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/285100
