A study on the quality of shelled eggs marketed in and around Hyderabad – India
This study was carried out with the aim of finding the quality of the shelled eggs marketed in and around the city of Hyderabad, which is the fourth largest city in India with a population of around 6,255,256. The population density of the city has been ascertained at 14,192 per square kilometre. This is the fastest growing city in India and its population is estimated to reach 10,457,000 by 2015. This study also applies to the other parts of the country as the same practices and techniques are practiced in the rearing, packing, transportation, storage and marketing of eggs.
The poultry industry is considered to be one of the richest in the country as poultry meat is the most preferred by the citizens. This is because of the large diversity in cultures, religions and customs and also because the price of chicken is low compared to the other meats. Therefore, shelled eggs are considered to be one of the best-selling agricultural produce in the country. However, India faces several problems as most of the farmers are poor and lack knowledge of the latest techniques and practices.
Improper techniques regarding rearing; such as the use of contaminated feed materials and using feed ingredients with no knowledge of how the nutritive value affects the quality of the final product. Unhygienic rearing practices are widespread in the country, as quality control measures such as in poultry production, are absent.
Samples of shelled eggs were collected from several parts in and around the city, from all parts of the supply chain i.e. every stage the egg passes through was assessed for the external, internal and microbial quality. Deterioration in the quality at different stages was marked and the reasons for this deterioration were evaluated and measures for preventing this deterioration were suggested. The harmful, disease-causing bacteria Salmonella entiritidis was found in some of the samples.
This study was done using the lab facilities at Loyola Academy Degree and P.G College (affiliated to Osmania University), which is located in the city of Hyderabad, India. The college is accredited by NAAC with ‘A’ grade. The lab is equipped with all equipment related to livestock production and microbiology.
The external and internal parameters of the egg were studied to find the overall quality of the egg. Techniques of candling, shell index, albumen and yolk index (percentages making up the physical composition of the egg) were used to evaluate the physical quality of the egg. The microbial aspects were studied by taking culture samples from the external part (shell) and the internal contents of the shelled eggs. Microbiological techniques such as streak plating and gram staining, along with the help of ready-made bacteria enumeration kits, were used to detect the type of bacteria present in a sample.
The enumeration of bacteria (microbial analysis) was done with the help of Himedia biochemical kits (bacteria enumeration kits). Ready-made culture medium (culture plates) was used for culturing the bacterial colonies. The tests were conducted in the sterile environment of a laminar airflow chamber. The biochemical kits contained 24 wells with different media in each well. The reactions of the culture in each well (depicted by a change in colour of the wells) were compared to the bacteria enumeration table provided by the manufacturer of the kits to get the result of the bacteria present in a particular sample.
Literature was reviewed relating to several aspects of egg quality to compare the findings with previous findings, and measures were suggested to improve the quality standards of the shelled eggs marketed in India.
The poultry Industry in India and certain neighbouring countries has faced a lot of losses over the past two decades due to a drop in consumption levels and the endemic bird flu (Avian Influenza, which haunted several Asian countries over the past few decades). However, my study is confined to poultry egg contamination. Shelled eggs are contaminated by several organisms. Contamination occurs either before the egg has been laid or after the laying has commenced. Most of the contamination is seen on the shell, however the internal contents of the egg are generally sterile as the shell and the shell membrane are mostly impermeable to microbes, and the albumen contains several antibodies to prevent entry and growth of harmful microbes.
India, with poultry population of more than 489 million and an estimated egg production of more than 47 billion per year, ranks among the top three countries in egg production in the world (FAO, 2002). However, practices followed in Indian poultry production are quite old. Most of the farms are small scale farms with 1,000 to 5,000 birds per farm.
Developed countries like the UK and the US take measures to sterilise the egg surface from every possible contamination (especially by Salmonella enteritidis). India does not take any such measures and hence the risk of egg contamination arises.
Most Indian farmers are ignorant of the latest management practices in keeping their birds safe and this makes them more vulnerable to the incidence of diseases, which may cause improper egg formation and ultimately lead to losses. Improper cooking is another important factor that leads to the spread of diseases. Several techniques have already been devised for safe poultry production, which are being followed in developed countries. However implementing these in India is a tough process, as the farmers are poor and ignorant and the farms are located at distant places devoid of marketing and storage facilities.
India today is one of the leading poultry producers in the world and also possesses the potential to dominate the globe in the near future. However, the quality of the end product is not very high. Moreover, poultry farmers, traders, exporters and consumers are not fully aware of the problems poultry can cause if contaminated with harmful bacteria and viruses in the end product.
The finished product is often not accepted by other countries because of the presence of chemical residues. Furthermore, India is not able to find suitable export opportunities because of lack of education in the above facts, despite of having good infrastructure.
The reasons for this are
- Poor farm practices
- Low quality feed and ingredients used in feed
- Old processing methods.
HACCP (Hazard Analysis Critical Control Point) procedures are lacking in Indian poultry processing, which gives a large scope for contamination and spoilage of the final product. There is no implementation of methodology to control critical control points in Indian poultry farms, which makes the customer more vulnerable to contaminants.
This study was carried out with an aim of finding the quality of the shelled eggs marketed in and around the city of Hyderabad, which is the fourth largest city in India with a population of 6,255,256 (population density of 14,192 per square kilometer). This is the fastest growing city in India and its population is estimated to reach 10,457,000 by 2015. This study also applies to the other parts of the country as the same practices and techniques are practiced in the rearing, packing, transportation, storage and marketing of shelled eggs.
- To study the normal physical and microbiological aspects of the egg
- To detect stages of contamination within the Indian poultry supply chain
- To detect several microbes which contaminate the egg
- Suggest measures to prevent the contamination
- Suggest measures to make safe shelled eggs available to the Indian customer
Finding techniques for the safe production of poultry is important. Raising awareness among farmers and consumers about the safe handling and consumption of the poultry products is necessary.
- To collect egg samples from several parts of the marketing chain in and around Hyderabad i.e., poultry farms, wholesale markets, retail outlets and butcher centres
- To review the literature available regarding the nature, spread and spoilage of shelled eggs
- To bring awareness of a HACCP plan for Indian poultry farms and processing plants
- Suggest techniques for safe production of eggs to Indian farmers
- Suggest measures for safe consumption of the poultry products
- To suggest steps for improvement of safety and quality in Indian poultry
As seen above, the main objective of the research is to study the quality of the poultry egg being made available in and around Hyderabad, from the time it has been laid to the time it reaches the consumer. The research was conducted in the city of Hyderabad, which is in the southern part of India. The study was performed in order to find out the constraints in egg production which lead to spoilage and the deterioration of egg quality. The microbiology and livestock management laboratory at Loyola Academy (India) was used to assess the various aspects of egg quality. The microbiology was studied by using professional and expensive microbiological equipment such as ready-made culture media, Salmonella medium, sterile transport swabs and Bacteria enumeration kits (Biochemical kits).
A study was done on several aspects such as egg formation, nutritive value of egg, external and internal egg quality and grading of shelled eggs in American and Indian standards (AGMARK). This helped me to compare my findings with the previous literature.
Egg samples were collected from different parts of the city and also outside the city from the nearby villages. The samples were collected from poultry farms, egg wholesale markets, retail outlets and butcher shops. These samples were studied for their quality traits by using candling equipment and the healthy shelled eggs were separated from the unhealthy shelled eggs. The external and internal aspects of the shelled eggs were studied and the shape index, yolk index and the albumen index were recorded. The overall quality of a batch (sample) was assessed by taking an average of the tests conducted on all the shelled eggs.
Microbial analysis of the external egg as well as the internal contents of the egg was undertaken. Spoiled shelled eggs were picked randomly from a sample and microbiological tests were conducted on them. Hi media biochemical kits were used to identify the organisms present in the shelled eggs and the danger posed by these organisms was evaluated based on the previous research.
The following are the various steps that were performed during the study.
Samples of shelled eggs were collected from poultry farms, wholesale and retail outlets in and around the city of Hyderabad in batches of 30 eggs each (one tray). Five samples were collected from each category (farms, wholesale and retail outlets). The poultry farms are usually located on the outskirts of the city from where the shelled eggs are supplied to the wholesale egg traders. Wholesale markets are the agricultural markets where farmers sell their produce and retailers procure the product. Five whole sale markets were selected to collect the samples. Samples were collected from 10 retail outlets as well i.e, five retail shops and five chicken shops (retail butchers).
In total, 20 batches of samples were collected, five each from poultry farms, wholesale outlets, retail shops and retail butchers. Each batch contained 30 eggs. The external, internal and microbiological quality of these 30 samples was evaluated. The procedure is detailed below.
All the shelled eggs were candled using a candling box. The candling box is a box which contains a 70 watt blue bulb and has a single circular opening to let the light out. The box is used generally in a dark room for best results. The egg is placed on the candling box with its broad end facing the circular opening. The internal contents of the egg are illuminated by the light and the quality of the egg can be thereby assessed.
A total of 600 shelled eggs were candled (all samples put together) from the 20 trays of collected samples. The number of healthy, cracked, stained and glassy eggs were recorded. Eggs with improper formation of the aircell and with improperly placed yolk were also recorded and the overall quality of a particular batch of shelled eggs was assessed by taking an overall average of the batch. Results of the canldling procedure are shown in the tables.
After the candling was completed, the shape index, albumen index and the yolk index of the shelled eggs was taken in the procedure given below. The shape index was taken for all the eggs in the individual trays but the albumen and yolk index was taken by selecting eggs randomly from a tray. Selection of eggs was based on the size and weight of the shelled eggs. The eggs were divided into three groups based on their weight – small, medium and large. Two eggs were taken from each groum from a tray so six eggs were evaluated per tray for the yolk and albumen index. The results of the 20 batches of eggs are are shown in the table.
Microbiological tests were conducted to find the presence of harmful bacteria in the shelled eggs. Cultures were taken from both the egg surface and internal contents. HiMedia Bacteria enumeration kit was used to evaluate the bacteria. (AN INTRODUTION TO THE KITS).
PROCEDURE: Sufficient number of beakers, test tubes, conical flasks were autoclaved. 200 ml solutions of Peptone Water and Nutrient Broth were prepared (Nutrient medium) in conical flasks of sufficient number and autoclaved. All the equipment was arranged in a Laminar airflow chamber.
Surface Cultures: 2 dirty (stained) shelled eggs were selected from each of the 20 trays for taking the surface cultures. Peptone water was poured on the eggs and thereby the surface of the eggs was washed into a beaker. The culture is thus collected in the beaker. This culture was incubated for 24 hours (at 32oC) in order to facilitate growth and multiplication of the bacteria. After 24 hours the beaker was taken and the cultures formed in it streak plated onto petri plates (count medium) under the sterile conditions of the Laminal airflow chamber. Streak plating was done with the help of sterile cotton swabs. These cotton swabs were stored in transport media for future use.
Internal Cultures: Cracked shelled eggs were used to evaluate the internal contents of the egg. This is because cracked shelled eggs have more chance of being contaminated with bacteria. Two eggs from each tray were selected. Nutrient broth of about 25ml was added to beakers and the internal contents of the egg were emptied into the beakers. The culture is thus collected in the beaker. This culture was incubated for 24 hours inorder to facilitate growth and multiplication of the bacteria. After 24 hours the beaker was taken and the cultures formed in it are streak plated onto petri plates (count medium) under the sterile conditions of the Laminal airflow chamber. Streak plating was done with the help of sterile cotton swabs. These cotton swabs were stored in transport media for future use.
These petri plates were incubated for 24 hours (at 32oC) in order to facilitate formation of bacterial colonies (along with a few fungal colonies). These cultures were inoculated into test tubes containing nutrient broth with the help of an inoculation loop. Sterile conditions were maintained during the entire process. The test tubes were again incubated for 24 hours (at 32oC). A dense precipitate is thus formed inside the test tube. This culture is inoculated into each of the 24 wells of the bacteria identification kits. These kits were again incubated for 48 hours, the results were compared to the charts given by the supplier of the biochemical kits and the bacteria in the samples identified. Salmonella entiritidis was the main bacteria that was identified. Eschericia Coli, Enterobacter aerogenes and Sheigella were the other bacteria found.
India, as seen in the introduction, is one of the top ranked countries in poultry production. But the rearing practices used are outdated and the hygiene levels practiced in farms are low. The level of hygiene maintained in the poultry farms has an effect on the quality of the shelled eggs also. It was observed that internal contamination of eggs by Salmonella enteritidis can be the result of penetration through the eggshell or by direct contamination of egg contents before oviposition, originating from infection of the reproductive organs (Gantois et al, 2009). The egg is thus vulnerable to attack by harmful microbes in several ways.
The overall quality (internal, external) of the egg plays a vital role in deciding the final microbial characteristics of the egg. Dirty eggs have a possibility to be contaminated with bacteria on the outside, cracked shelled eggs may contain bacteria on the inside. The thickness of the shell plays a vital role in preventing bacterial penetration thus eggs with thin shells are more prone to microbial attack. Moreover the internal quality of the egg i.e. the amount of yolk and albumen also play a vital role in microbiology of the egg. The albumen (white) of eggs contains several antimicrobial agents (like conalbumin) which restrict the growth of invading microbes provided the level of contamination is low (forsythe et al, 1998).
Thus in my study, the overall quality of the poultry eggs marketed in and around the city of Hyderabad was studied. It was essential to study the overall quality of the shelled eggs from the external parameters of the eggs to the microbiology. The shelled eggs were studied from the farm stage until they reach the consumer to assess the change in quality.
Firstly, the shelled eggs were candled and the results showed that all the batches contained a few eggs which were dirty, cracked or glassy (eggs with weak shells) thus making it clear that there is a chance for bacterial contamination. However the number of cracked eggs was higher in the samples from the retail outlets than the eggs from farms.
Later the physical quality of the shelled eggs was studied i.e. the composition of the egg contents (shell, albumen and yolk) It was observed that all the batches of eggs collected were normal in their physical form. Even though there were few unhealthy eggs in the batches, they were not recorded as the readings were taken as an average of all eggs in the sample.
Microbiological tests were performed. Surface cultures were taken from the shelled eggs which were dirty on the surface and internal cultures were taken from eggs which had cracks. The enterobacteriaceae identification kit was used to find the bacteria present.
The batch samples from farms and wholesale markets contained little or no bacteria, therefore they were not considered for bacterial enumeration as the number of colonies formed from these batches were very few and thus has little or no chance of causing disease. Whereas all the five samples collected from retail outlets contained salmonella in large amounts, both on the outside (shell) as well as the inside.
From the tests performed, it was concluded that the levels of salmonella were very high in the samples collected from retail outlets compared to fresh eggs from farms. Most consumers purchase shelled eggs from retail outlets as they are the most convenient. Therefore people are at risk of salmonella infection.
The deterioration in the quality of shelled eggs is due to lack of safety procedures, storage facilities and improper transportation. In developed countries like the UK and US, shelled eggs are washed to prevent contamination. Techniques must be developed in Indian poultry farms to prevent the contamination at farm level. Additionally, storage facilities during transport and marketing must be improved.
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