Food adulteration can be defined as adding removing or replacing any substance which will eventually exaggerate the natural quality of any food product. Producing food with high quality and safety should be the main focus of food industry. But as in for today food manufacturers are more tend to manufacture food with adulterants (Mi et al., 2015). These food adulteration can be unintentional or intentional. Unintentional food adulteration is a result of ignorance or lack of facilities to maintain food quality. Intentional food adulteration is done by manufactures to gain more profit. Most of the time these manufactures only look after their profit not the public health who consume the food. In a transition era which most of the people are starting to focus on having vegan meals as for health issues, as some individuals are allergic several meat products such as pork and chicken. And also for some religious beliefs such as halal food. Food manufactures are more tend to adulterate vegetarian food with types of meat in order to enhance the taste and smell of the food to gain more profit (Cheng et al., 2019). This fraud food adulterant is a major problem which have an impact on consumer confidence on vegetarian prepared food which is in the market today. A common type of food adulteration is contamination of chicken in vegetarian food. Most common types of vegetarian food which has a higher probability of adulteration are the products which are sold as vegetarian sausages, vegetarian meatballs and vegetarian nuggets. Considering the reasons why manufactures tend to use chicken in vegetarian food, it has been found out that meat of chicken has the ability to enhance the taste as well as the smell of the prepared food comparing to other taste enhancers available in the market today. Intentional and unintentional chicken meat contamination in vegetarian food is a major health issue, as some individuals specifically presented with allergic to chicken meat. Some of these allergies of chicken meat can be lethal. However individuals who are allergic to chicken often allergic to other bird meat such as dove, quail, goose, and turkey (Fujimura et al., 2008).
DNA based detection methods have drawn attention over the years as they are fast and accurate. This method is often sensitive and specific. Using DNA labels and use of polymerase chain reaction (PCR), these traces of Chicken DNA can be detected. Polymerase Chain reaction (PCR) has the ability to multiply and make thousands of copies of a single strand DNA or RNA in a matter of minutes. Considering the amount of meat of chicken available in vegetarian prepared food products as they are only added as taste enhancers, PCR plays a key role being able to multiply the DNA available in trace amounts in the sample. PCR detection of chicken DNA can be done routinely in a laboratory to identify chicken contamination in vegetarian food and even to identify other type of adulteration which involve chicken contaminations.
As it is mentioned above, food adulteration mislead consumers and weakens the consumer trust. Therefore suitable methods of detecting such food adulterations are now available. But there are several challenges when it comes to detection, most important and common barriers are, most of the time analytical methods usually vary depending on the type sample, as in for , solid, semi- solid and liquid samples and also depend on cooked and un-cooked samples. And another challenge is to use a specific marker, the marker which is used to identify the adulterant should be highly specific (Primrose, 2019).
Physical and Biochemical Methods of detection
Considering the available methods, there are chemical and physical methods and also some of the methods are molecular methods which deals with the most important functional and structural unit of life which is the DNA (Deoxyribonucleic Acid). Most of the time detection method vary depending on the sample using. For an example to identify meat adulteration there are physical methods which include comparing the colour , texture , consistency and marbling between types of meat. Considering biochemical methods of detecting food adulterations, there is gas chromatography which is combined with a very powerful detector, the mass spectrometer has the ability to identify food adulteration and also adulterations in beverages as well. Gas chromatography and Mass spectrophotometer can be used combined and also as two different detection methods (Posudin, Peiris and Kays, 2015). ELISA also can be used to identify contamination of chicken in various type of food. This technique can be used to identify type of antigens or proteins in chicken meat by using monoclonal antibodies. Sandwich ELISA is a specific type of ELISA which has a higher accuracy than the general ELISA technique (Martín et al., 1991). Nuclear magnetic resonance has the ability to identify contaminations in food samples, it has the ability to identify adulterant and also to prove structural identification of the contamination. Although physical and chemical detection methods are easy and cost effective for routine laboratory detection methods, the results generated by these techniques can be less accurate and specific.
DNA based detection methods
A challenge which can be encountered in detecting is, most of the time specific markers will not be available as some types of processed food and contaminations can vary geographically as well. Therefore DNA based detecting methods has drawn attention as they can more accurate, specific and time efficient comparing with other physical and chemical methods (Bansal et al., 2015), (Primrose, 2019). Using a DNA based detection methods to identify food adulteration can be advantageous when the adulterants are biological substances. All cellular organisms contain DNA therefore there are various methods which can be used, such as microarray, southern blot, polymerase chain reaction (PCR) and Random Amplified Polymorphic DNA. Microarray have the ability identify and hybridize with the complementary strand in the sample, and then graphically indicate if the relevant DNA is present in the sample or not.
Why PCR is the ideal detection method?
Most important DNA based method is the polymerase chain reaction technique (PCR). There are several types of PCR available which has specialized features. Generally PCR has the ability to produce large amounts of DNA products from a single DNA template. Since there are several types of PCR available and each of the type has a specific feature, for an instance Real Time PCR has the ability to present a real time graphical quantification of the PCR products. And reverse transcriptase PCR has the ability to produce copies of DNA using a RNA template. Using PCR instead of other DNA based methods and other type of physical and biochemical methods is beneficial as PCR has the ability to identify pathogens present in food. And also PCR is ideal to identify chicken meat contamination as the food products with chicken contamination undergo various processes such as baking, frying and boiling, even after the sample undergo such alterations PCR has the capability to detect chicken DNA (Fujimura et al., 2008). Basically the PCR technique is a very simple, less time consuming, accurate technique which also has the ability to detect considerable amount of types of meat and other food types even though they have undergone food processing.
However this technique also has its own limitations. PCR is not a very sensitive technique, therefore the sample should be extracted properly, DNA extraction from processed food is difficult procedure to carry out, if the DNA extraction has not carried out properly, impurities can inhibit PCR or alter the products of the PCR. Therefore, considering the available DNA extraction methods to extract DNA from vegetarian food products. CTAB (Cetyl Trimethyl Ammonium Bromide) DNA extraction method is a protocol to extract DNA from plant cells. As the sample of interest is vegetarian processed food, CTAB method is the ideal DNA extraction method which can be followed. The purity of the extracted DNA can be determined by a spectrophotometer (Mafra et al., 2008). And also researches have shown when detecting chicken meat DNA in vegetarian food samples, DNA extraction should be done to extract chicken DNA as well, therefore using standard protocol DNA can be extracted (Kumari et al., 2015). When the DNA is extracted properly according to the given protocol, PCR can be conducted with the use of primers which have the ability to detect the specific type of species in the sample. In a situation which is to identify chicken meat contamination in vegetarian prepared. Two types of primers can be used one primer is to detect the chicken meat DNA if present , and the other primer is to detect the other vegetarian food substances in the food product as it marketed as “vegan food” . Considering the possible primers which can be used, most important one is trnL. Chloroplast trnL (UAA) has been an important intron to detect plant species. This gene has its specific advantages as this trnL (UAA) has thoroughly investigated including its evolution for the past years. Also the low intraspecific variation indicate a greater benefit if the amplicons produced to be hybridized. (Taberlet et al., 2007). And for chicken meat there are few primers which can be used one of important primer is Cyt b gene primer. Cyt b gene is a mitochondrial DNA, it the most extensively used and sequenced DNA for vertebrates and also like the trnL gene, Cyt b gene’s evolution is well observed. Therefore it’s very advantageous (Yacoub, Fathi and Sadek, 2013). Using these two primers can be an ideal manner to identify the chicken contamination in vegetarian food.
Worldwide reported incidents of meat contaminations
There are considerable amount of instances and incidents, where food manufactures contaminate meat in various types of food. This is a very common in the sector of processed food. Food manufactures contaminate cheap types of meat with very expensive types of meat. Most common type of meat adulteration according to reported incidents is addition of pork meat with other type of processed meat in order to reduce the production cost. However this a crucial issue due to various religious and health purposes (Ha et al., 2017). Also another research has been carried out identify the chicken meat fraudulent, and the researchers have identified turkey meat in several products which have labeled has chicken (Abuzinadah et al., 2013). Other than adulteration of meat with other type of meat species, food manufactures tend contaminate vegan food products with meat, this type of incident has reported in United kingdom, a team of research has been able to detect pork and turkey traces in two types of vegetarian food products (Morley, Heighton and Newell, 2018). Furthermore contamination of chicken meat in vegetarian food should be further investigated.
How Chicken meat can be a food additive? The chemistry behind.
Flavor comprises mainly of taste and aroma. Today most of the food manufactures tend to use flavor additives in all kind of food products. Most common type of food additive used in ready to eat food are meat stock cubes. Meat stock cubes can act as taste and smell enhancers. There are beef and chicken cubes widely used in food industry. According to researches, because of the chemical combination that is formed when chicken is being cooked, it has the ability to act as a flavor enhancer. However chicken meat flavor also depend on few production and processing factors such as breed of the chicken, diet of the bird and availability of free amino acids and nucleotides. And also as in for the postmortem factors depend on flavor irradiation, high pressure treatment, cooking, antioxidants, and pH and ageing are important. (Jayasena et al., 2013). Most of the counties even in Sri Lanka use chicken cubes as a flavor enhancer. These chicken cubes are available in beef cubes. They are basically a concentrated broth of chicken or beef. And these cubes are used in many different cuisines including vegetarian food products because of its ability enhance the flavor of any kind of food product. And also it has been found out that these chicken cubes have a protein concentration of 8.6%. (Al-Subhi, 2013)
Risks of chicken contamination in food, Health issues
Some individuals avoid chicken meat and some of the other meats due to various health issues. Considerable amount of people get anaphylaxis due to chicken meat. And also these individuals are allergic to other type of bird specifically. Most of the individual who are allergic to chicken meat can be not allergic to eggs or feathers (Can, Yazicioglu and Ciplak, 2014). Other than anaphylaxis, contamination of chicken meat without any proper preservative methods can cause other types of allergies and also can cause infections. Taking an account of statistics of poultry meat production from year 2000 to 2014 global production of poultry meat has increased in 58.8 million tonnes. Salmonella and Campylobacter are the most common bacterial infections associated with chicken meat. (Antunes et al., 2016 ),(Skarp, Hänninen and Rautelin, 2016).Other than the clinically evaluated diseases consumption of chicken contaminated food cause secondary effects as the chicken meat itself can be contaminated with antimicrobial, antifungal chemicals and also with pesticides. Contamination of chicken with such chemicals is a result of poor farming management.
Considering the above mentioned factors there’s need of producing 100% vegetarian food products in order to gain consumer trust as well as to improve healthy lifestyle. There are several researchers which have carried out to explore alternative vegan food additives. And according the research, authors have found out that mushroom stock cube has the same amount of nutrients as a common chicken stock cube, in fact they have also found mushroom cubes contain less amount of microorganisms compared to the chicken stock cube. Therefore mushroom stocks can be used as a very good substitute for chicken cubes in vegetarian food products (Al-Subhi, 2013).Soybean is another type of food additive that can be used instead of chicken meat. Soybean oil as well as soy lecithin can be used as taste enhancer, preservative and also as an emulsifier (Mortensen et al., 2017). Another type of taste enhancer which is derived from soybean in soy sauce. Soy sauce is a very common type of taste enhancer used many of the East Asian countries as well as in Sri Lanka (Kong et al., 2018). Vegetable stock cubes also can be a substitute for meat stock cubes and other meat taste enhancers. And can be used in various food products including vegetarian food products.
Future aspects and Novel methods of detection
Some of the food adulterants cannot be detected by the current detection methods. For an example when using PCR assay, the DNA extraction protocol should be properly followed to extract proper amount or pure DNA sample, for the assay to continue. While PCR assay being the most ideal technique which can be used currently. New aspects of detection methods should be considered. DNA based method being a specific technique, DNA foil technology could be the future of food adulteration detection. This method is very rapid and a simple technology which a household individual can use instead of a PCR which can be only used trained individuals. This new technology can break, lyse, extract, neutralize and stabilize DNA from various food matrices. And then to identify the target DNA (El Sheikha, 2019). Another novel method to detect food adulteration is by using a digital image processing technology with digital camera. This technique is based on the texture of the food therefore depending on the texture feature values this method can evaluate if the food has been adulterated or not, and also this technique has the ability to determine the quantity of the adulterant (Raja and Victor, 2017).
Considering the future aspects of food adulteration, rather than inventing new technologies to detect food adulteration, as scientists it should be a priority to minimize such food adulteration. As food manufactures those authorities should acknowledge the consequences of food fraud consumers are facing. Therefore not only scientists as well as the food manufactures should be responsible of minimizing food adulteration worldwide. Instead of using unhealthy cancerous food additives and poultry meat species just to enhance the taste and get more profits, scientists as well as food manufactures should be innovative to find additives which will enhance the taste of the food and simultaneously which will have health benefits.
Taking an account of all the above mentioned facts, food adulteration is major problem worldwide. Due to economic advantages food manufactures tend to alter food. Food adulteration has impacted on consumers in various aspects. Because there are individuals who doesn’t consume some of the food products due to health and religion issues. These consumers’ confidence in food manufactures have weaken. Here in this review, it has been discussed issues with intentional and non – intentional contamination of chicken meat in ready to eat vegetarian food in the market today. According to the sources found, contamination of chicken meat as a food additive in vegetarian food has major impact on consumers who have avoided consuming chicken due to health and religion issues. And also the some of the researches have described about various detection methods which can be used to identify such adulterations. PCR is a DNA based which is used by scientists to detect such food adulteration currently. And it has been mentioned that it is the most reliable technique up to now. However novel methods are being innovated to detect such adulterations rapidly and easily. But as scientists it is our responsibility to minimize food adulteration and introduce healthy food products to the world.