Effects Of Different Doses Of Gamma Ray Irradiation Biology Essay

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The research was carried to examine the effects of different doses of gamma-ray irradiation on physicochemical properties of flour and starch granule structure of wheat when compared to non-irradiated wheat. Irradiation by gamma rays is to protect the wheat from rodents, insects, pests etc and to ensure the quality and safety during storage. Lower ranges of gamma radiation can also increase the shelf-life period. The results revealed that the moisture content of wet gluten and titratable acidity were greatly affected by irradiation treatment. Their values decreased as the dose of gamma-rays increased. The micro-structure of wheat (starch granules) was also affected due to gamma-rays. The reason behind that could be the free radicals liberated by gamma-rays disrupts the α-(1-4) and α-(1-6) linkages in the amylase content of starch. The parameters of flour viscosity were decreased with increase in gamma-ray dosage. On the contrary, there was no significant effect on dry gluten content, ash and protein contents. Hence the gamma radiation has shown a significant effect on the physicochemical properties of flour and starch granule structure of wheat.

Wheat is the most widely grown cereal in the world and its production is increasing globally. Since wheat is rich in carbohydrate (starch), gluten and its derivatives, it has become the national staple food of 43 countries. The physicochemical properties of wheat flour such as gluten index, fat acid value, amount of protein, ash content etc determines the quality of wheat. These properties can then be related to components in wheat like starch, fat, ash, enzyme (Hoseney, 1994). These properties may vary due to various factors during cultivation (weather, fertilization, and temperature), storage (humidity, storage time, temperature) and post-harvest processing (milling). The protein content can be increased by N-fertilization during cultivation of the wheat. Elevated temperatures during storage and 2nd milling during processing of wheat can also alter the protein quality.

The harvested grain has to be stored for a long time in the developing countries. During storage, severe losses of grain happen due to the invasion of insects, rodents and pests (Gralik and Warchalewski, 2006). Effective storage techniques are required to prove the safety and quality of wheat during storage (Jin song, Harold and Yi-Zhong, 2009). Recent developments in processing of post-harvest grain involve the Gamma-ray irradiation, an ionic and no heat process to protect wheat from insect infestation and microbial contamination (Jinsong et al, 2005). Lower doses of gamma-radiation can also increase the shelf life period of wheat. The effect of gamma rays on foods especially wheat and rice have received wide importance because of food safety interests. Using gamma radiation on foods is internationally recognised for maintaining the quality of foods for a long time (Suhag, Racova, Polovka, 2006). This method of irradiation is followed in many countries but there is some contradiction in some countries. The reason for this is because of the influence of gamma radiation could result in change in the quality. It has been testified that gamma radiation generates free radicals that cleaves larger molecules like proteins and fats into smaller fragments like Dextrin. Hence, before irradiation of wheat grain by gamma-rays, the aftermath of the treatment and its influence on the physicochemical properties of wheat should be considered.

The introduction is focusing on the physicochemical properties that are affected by gamma-ray irradiation treatment, organisms that are responsible for wheat grain losses, how gamma-ray irradiation can prevent these losses and the advantages and contradictions involved in gamma-irradiation process. The introduction clearly stated the main objectives of the study; the effect of gamma-rays before wheat drying, on the physicochemical properties and on the starch granule structure with the aid of an electronic microscope.

Hypothesis Testing

Setting up a hypothesis and testing it is the basis for any type of research design. A hypothesis is an assumption that has been put forward because it is conceived to be true but has not been proved. Once an assumption has been developed, it can be resolved into two hypotheses between which one hypothesis is accepted; the null hypothesis against the alternative hypothesis.

The hypothesis being tested here is that "effect of gamma-rays on physicochemical properties, flour viscosity and microstructure of wheat".

Null Hypothesis:

A Null Hypothesis is a statistical test that proposes that no statistical significance exists in a set of given observations. It is used to find out the difference or relationship between two variables with the notion at the beginning that there is no difference between the two variables. A null hypothesis is tested for possible rejection under the presumption that it is true. Depending on the data, the null hypothesis is either will or will not be rejected but can never be accepted. It is denoted by H₀.  

Alternative Hypothesis:

If the data is strong enough to reject the null hypothesis, then the null hypothesis is rejected and alternate hypothesis is accepted. If the null hypothesis is rejected (p<0.05) in favour of alternative hypothesis it concludes that there is a significant relationship between the two groups or variables, indicating differences between the groups. Alternative hypothesis is denoted by H1.

Errors in Hypothesis Testing:

Two types of errors may arise during hypothesis testing.

Type 1 Error: Occurs when null hypothesis (Hâ‚€) is rejected when it is actually true. That is, H1 is wrongly accepted.

Type 2 Error: Occurs when null hypothesis is not rejected when it is actually false. That is, H1 is wrongly accepted.

General Design for Research

The design for the research is basically that wheat was obtained and after drying five samples of wheat at 105⁰C, the moisture content (25%) was determined. The dried wheat was divided into five samples and packed in polythene bags. The samples were then exposed to gamma irradiation at different doses like 0 kGy, 0.6, 1.5, 2.4 and 2 kGy respectively. The samples were then taken for micrology observation to analyse the effect of irradiation on the starch granule and structure of wheat grain; microstructures of irradiated samples were prepared and observed by using a XL30-ESEM electron microscope. Wheat grains were cut with a knife and the untouched broken surface was picked up for micrology observation.

The irradiated samples were then dried in an oven at a constant temperature of 50⁰C until the moisture content reaches to 13.5%. The grain was milled and the wheat flour was obtained after separating the bran. The observations done were that for:

Gluten content: 25gms of flour was mixed with 12.5 mL water and the resulting paste was

washed with water for 10min by using a Perten Glutomatic Gluten Index Machine. Then the wet gluten piece was centrifuged for 1 min using a Perten Centrifuge that gives the wet gluten yield. The wet sample is dried for 30 min and after cooling gives the dry gluten weight and the corresponding percentages were calculated.

Titratable Acidity: 100g sample (Triplicates)is neutralized with sodium hydroxide, using

phenolphthalein as an indicator.

Ash Content: 2g of each sample (Five samples) were incinerated at 910⁰C for 3h in an oven.

Protein Content: determined by Kjeltec TM 2300 Analyser.

Determination of Starch Viscosity: 3g of sample and 25 mL water were mixed thoroughly and

the resulting mixture is sent into Rapid Visco Analyser for Starch Viscosity Determination.

Phenolphthalein was used as an indicator for determining the Titratable acidity according to the AOAC International procedure, 1990. Even, the methodology followed for determining Ash content was setup by American Association of Cereal Chemistry (AACC).

All the methods followed were standard methods and are internationally recognised indicating a good methodology overall. The author has used the reports of FAO/IAEA/WHO/ICGFI and confirmed that the irradiated foods are nutritionally rich and safe for human consumption. However, some sections need a few adjustments. If the wheat samples would have been collected from different places apart from sticking to one place, there would be a better opportunity to compare the results obtained for different varieties of wheat grown in different climatic conditions. The author carried his research on only one wheat species; the physicochemical properties may vary between different species of wheat grown in different climates. The negative impact of gamma-ray irradiation treatment on larger molecules like protein etc was not enlightened in a proper manner.

There are no indications that the overall gamma-irradiation treatment was operated effectively and there were no signs of recognition by the USDA or the FDA. The storage conditions can also change the grain quality, gluten content, enzyme activity etc (Mehmet Murat Karaog lu, Melek Aydeniz, Halis Gurbuz Kotancilar & Kamil Emre Gerc¸elaslan, 2009). The author has not mentioned about the factors (storage conditions) that may influence the physicochemical properties other than gamma irradiation.

Evidence Based Methods:

This is of prime importance while carrying out a research. This method is used to ensure that the researcher has thorough knowledge of certain evidence before starting the research and has used qualified material to carry the research. Another important step while doing a research is to avoid any kind of subjective influence or bias. Therefore, the researcher should clearly define the population that is being targeted.

The main aim of this is to assure the readers that the best possible treatments were used in the research. In an effort to avoid the bias, the author has analysed the sample in triplicates for determining the titratable acidity, ash and protein contents. Techniques like heating and drying were done at suitable temperatures recommended by international associations like AOAC and AACC. All these procedures prove that appropriate steps have been taken to eliminate bias to a larger extent possible.

Statistical Analysis

Data is of many types namely categorical, continuous and discrete. Categorical data is further divided to nominal and ordinal data. Nominal data are values that can be assigned a label in the form of a number. If a data set can be ranked or put in a sequence, it is called an ordinal data. Values are distinct and separate in discrete data. The data obtained in this research is continuous data; if a data can have values/ observations within finite or infinite range, it is called a continuous data set.

Data was subjected to Analysis of Variance test (ANOVA) which is the appropriate method for the current situation. The author has used standard deviation, F-test and LSD test to interpret the results clearly. ANOVA is used to compare more than two treatments or groups at a time. In the current situation, the wheat irradiated with gamma rays was compared with non-irradiated wheat to see if there were any significant changes in wheat structure, ash content, and protein content etc. From table 1, we observe that the p value is less than 0.05 which indicates that there was a significant difference observed in Wet gluten content, moisture of wet gluten content and titratable acidity when compared to that of non-irradiated wheat. There is no significant difference (p> 0.05) in values of dry gluten content, ash and protein content. From figure 2 and table 2, we observe that irradiation has a significant effect on peak viscosity, hot pasting viscosity and cool pasting viscosity (parameters to measure flour viscosity) and microstructure of wheat grain. Hence null hypothesis is rejected which assumed that there was no significant difference between the irradiated wheat and non-irradiated wheat referring to wet gluten, moisture of wet gluten content, titratable acidity, microstructure and flour viscosity. Contrary to this, null hypothesis is not rejected for ash and protein and dry gluten contents.

The alternate statistical method that can be proposed is Linear Regression Model. Out of the two regression models, namely simple and multiple regression, the multiple regression model could be the best model that can be proposed for the current situation. This is used when the response of one variable is explained by changes in other variables.

There is only one graph that the author has put on. It is very clear showing the viscosity changes for different doses of irradiation at different times.

Intellectual Property Rights

"Intellectual property rights (IPR), are the rights granted to creators of any human intellectual creativity". The major Intellectual property rights include patents, copyrights, trademarks, design rights, moral rights, performers' rights and rights to prevent "passing off" and breach of confidence. IPR can be granted to any creation related to industrial, scientific, literary and artistic fields.


Patents are the rights granted to the creator of an invention by the government for a definite period of time. In fact, the inventor's property cannot be used by anyone without the grant of license by that inventor. A patent let inventors to benefit from their inventions. It also protects any unauthorised buying or selling of an invention. The methods employed in the current research were not innovative; in fact the author has used the methods that were already been in use. Gamma ray irradiation method has been in use before this research. Therefore, there would be no need to patent this research.

Health and Safety:

Health and safety should be given the paramount importance. The author has stated that according to FAO, irradiated wheat is nutritionally safe for consumption but it depends on the irradiation dose. This statement is further supported by The United States Public Health Service, The American Medical Association, National Association of State Departments of Agriculture, The Institute of Food Technologists and the World Health Organization. The process of irradiation should be carefully monitored since any small mistake will lead to a severe fatal accident. Exposure to gamma rays even for a short period of time will lead to cancer. Only trained personnel should control the gamma irradiation. Also, some of the reagents used are of high health risk as they are carcinogenic and may even lead to death. While handling the reagents, safety measures such as gloves, goggles and lab coats are must.


There are no ethical issues taken into consideration, as there were no human or animal populations used in this research. If in any research, humans or animals are involved, researchers should follow strict ethical procedures as they are meant to be.

Quality Control:

For any research to get accurate results, quality assurance procedures should be followed. Laboratories with advanced technology instruments and highly qualified personnel should be selected to avoid the errors in the results. The accreditation of the laboratory should also be verified as only the laboratories which maintain standard techniques will be accredited. The quality control employed in this research was good and the equipment like electron microscopes, ion coaters etc are all adequate for the research.


The research was conducted in a well designed manner. The results were presented properly and the significance is clearly explained. There was no confusion with the graphs and tables. The sample was analysed in triplicates and hence the desired accuracy could be achieved. The hypothesis is clear explaining the effects of gamma irradiation on physicochemical properties and structure of wheat. The design is adequate to prove the hypothesis. Appropriate statistic method was used. However, there are areas that need improvement. The results would have been more accurate if samples of different species were collected from different places. But, the experiment in overall was very good.