Contributions of Omics Approaches for the Detection of Food Adulterants
Issues regarding genuineness and safety of imported foods have amplified due to the globalization of food market. Any form of food variation that may occur throughout artisanal or industrial manufacturing processes to which consumers are susceptible and attention towards elements of food is a must as these can have a serious impact on the nutritional and health conditions (Galimberti et al., 2013; Byrd-Bredbenner et al., 2015; Remington et al., 2015; Gharibzahedi and Jafari, 2017). Adulteration of food is a common problem found in low- and middle-income nations but occasionally in some developed countries (Faour-Klingbeil and Todd, 2020; Grace, 2015). The countries having low-economic zones, such as some of the Asian nations like Bangladesh, Indonesia, India, Vietnam, and many African countries are suffering more. This kind of practice is done simply to increase their earnings with less investment and equipments (Hossain et al., 2008; Rashid
2007a; Hoffmann et al., 2019). There are reports of planned intercontinental food fraud where the seeds imported from numerous non-EU countries, are mislabeled as organic and shipped to EU countries via Malta or Italy, involving seven countries in total and thousands of tonnes of com, soybeans, wheat, rapeseed, and sunflower seeds (Delwiche, 2016; Kim et al., 2020; Celik et al., 2019; Zio et al., 2020).
Exhaustive labeling and reporting details about the original raw materials in packed foods is done due to enhancement in awareness of the consumer in terms of food quality and safety which has led to search for products giving guarantees about the lack of injurious chemical and microbial impurities (Van Rijswijk and Frewer, 2008, 2012; Nocella et al., 2014). Food adulteration topics have driven to the expansion of new diagnostic tools in the context of food science (Garcia-Canas et al., 2012; Kalpana et al., 2019; Kumar et al., 2019). The consumers' concern about what is in their food and the safety of the food they eat has led to the growth and application of diagnostic methods and techniques in food science. Foodomics is the omics" technology applied in food analysis (Garcia-Canas et al., 2012; Pimentel et al., 2018; Xu, 2017). These techniques are often more sensitive and specific alternatives to identify, monitor the food contamination due to microbes and their toxins, and also certify the preexisting methods used to explore the quality of food (Dupuis et al., 2008; Gaso-Sokac et al., 2010; Giacometti et al., 2013).
DNA-based technologies have greater acceptance due to proper authentication satisfaction achieved by the customers and this has led to a greater demand (Galimberti et al., 2013; Bohme et al., 2019). There are various factors which contribute to this greater demand as shown in Fig. 1. This chapter discusses various omics approaches employed for the detection of food adulterants.
Figure 1. Factors responsible for demand of DNA-based approaches.
Food Adulterant Issues
There are various chemical intoxicants which are responsible for causing doubts about the quality of food among the people and these are discussed in the following sections.
These are the potential chemicals which are used since the Green Revolution to kill pests, microbes, and insects that are responsible for causing serious damages to the crop. There are various kinds of pesticides based on their chemical nature and also on the target organism which has led to use of their unprecedented amounts in the soil. It has been observed by scientists that ultimately these pesticides are finding their way to crops and finally on to the plate of the human being (Pang et al., 2020; Carvalho, 2017; Reeves et al., 2019; Mahmood et al., 2016). Several health-related issues have been identified in persons who are consuming the pesticide-affected food. Among the category of children, newborn babies are more susceptible to the effect of pesticides and even the unborn babies are also affected from the mother (NRDC, 2001; Cho et al., 2016; Fatma et al., 2018; Sapbamrer and Hongsibsong, 2019). Many harmful pesticides having more half-life are banned (Kaur and Goyal, 2019; Gupta and Gupta, 2020).
2.2 Heavy Metals
Metals are a potential part of the various food material due to contamination of water supply. Many researchers have proposed the contamination of foodstuff by heavy metals. One such recent study by researchers from Pakistan have reported the presence of five heavy metals, i.e., lead (Pb), Cadmium (Cd), copper (Cu), zinc (Zn), and nickel (Ni) in milk (Yi et al., 2017; Atooh and Sowley, 2018; Hembrom et al., 2020; Balint et al., 2018). Their concentration is more than the recommended levels by the International Dairy Federation (Arif et al., 2019). Islam et al. (2014) studied the effects of the presence of heavy metals, mainly nickel (Ni), cadmium (Cd), lead (Pb), zinc (Zn), arsenic (As) and copper (Cu) in cereals and pulses on the health of people in Bangladesh. The target hazard quotient and hazard index were assessed to evaluate the carcinogenic risk associated with such adulteration. The concentrations of As and Pb were found to exceed the permissible limit and would certainly cast a carcinogenic impact besides causing nutritional deficiency (Islam et al., 2014). Redan et al. (2019) reported the presence of high concentrations of heavy metals like As, Pb and Cd in the alcoholic fermented beverages which were using diatomaceous earth (DE) in the filtration process. The chemical properties of the beverage and type of filter used were found to be the major driving factors for heavy metal introduction. Treating DE with Ethylene Diamine Tetraacetic Acid (EDTA) mitigated the Pb amount while the mixture of water, citric acid and EDTA reduced the as amount to a significant extent in beer and wine under investigation (Redan et al., 2019).
2.3 Antibiotics and Hormones
Antibiotics were given to many animals to treat against various infectious diseases. Previously milk having less bacterial count was considered as pure but later milk containing its residues led to great concern regarding its usage. And they were labeled as food adulterants. According to a study by the Centre for Science and Environment, many brands of honey sold in India contain different amount of antibiotics (Mendez et al., 2017; Gauglitz et al., 2020; Cheng et al., 2019; Gomiero, 2018). Consumption of antibiotics like this can lead to development of resistance and some serious disorders might also occur (India Today, 2018; Dickey et al., 2017). In the past few decades, the presence of several antibiotics, like tetracycline, macrolide, aminoglycoside, penicillin, and amphenical are reported in the food products (Ronquillo and Hernandez, 2017). Due to incomplete absorption and metabolization of the antibiotics and hormones injected in the animal body, large concentrations of these are excreted directly into the sewage system and waste water movement leads to their dispersal into the environment, thereby, affecting the animal and human health (Kim et al., 2013; Bartelt-Hunt et al., 2011). Kolodziej and Cwiertny (2012) reported the adverse effect on the ecosystem due to the presence of synthetic hormones and their degradation products in the fresh water sources (Kolodziej and Cwiertny, 2012).
2.4 Radio Nuclides
The presence of radionuclides is responsible for the contamination of food depending on the type of soil, uptake and accumulation by the plant, and chemical characteristics of the radionuclide (Samavat et al., 2006). By means of gamma ray spectrometry, various food crops that are commonly consumed by the people of southern region of India were estimated for the presence of 226Ra, 22sRa, 22sTh, 40K. They reported high concentrations of 40K in rice and tapioca. In their study, they mentioned that high amount of radionuclide in food crops might be due to the enhanced use of fertilizers (Shanthi et al., 2010; Rolle et al., 2017; Weller et al., 2018; Elsaman et al., 2020). Shigeoka et al. (2019) reported the devastating influence of the earthquake and tsunami observed in Japan in the year 2011. The Fukushima Daiichi nuclear power plant directly added large-scale quantities of radioactive material into the water bodies and contaminated the marine ecosystem. All the 15 marine algal species and sea-grass species under investigation were found to be loaded with UOmAg, 134Cs, and 137Cs radioactive nuclides (Shigeoka et al., 2019).
Preservatives have been used to enhance the shelf-life of food. But usage of many preservatives was considered as adulterants as they are responsible for posing a threat to human life (Rosculete et al., 2019; Linke et al., 2018; Khoshnoud et al., 2018; Mirza et al., 2017). One such example is the usage of formaldehyde to preserve milk. There are reports of cases where sulphites are added to wine and dried fruits so as to prevent bacterial spoiling and browning, respectively. Nitrates and nitrites are used as additives for bacon, sauces, etc. to enhance their color and shelf-life. They generate nitrosamines, responsible for causing cancer (Mohammadzadeh-Aghdash et al., 2019; Abusaloua et al., 2019). Esimbekova et al. (2017) reported the negative impact of food preservatives on protein digestion. The activity of pancreatic enzymes, chymotrypsin and trypsin, was highly altered in the presence of food preservatives, such as sodium benzoate, sorbic acid and potassium sorbate even at low concentrations. It was also observed that with passage of time, adverse effects of these chemical moieties on human metabolism tend to proliferate (Esimbekova et al., 2017). Hmcirova et al. (2019) studied the activity of intestinal bacteria under the influence food additives. Bacteroides coprocola and Clostridium tyrobutyricum displayed extreme sensitivity to sodium nitrite. However, sodium benzoate and potassium sorbate were observed to influence the microflora of Enterococcus faecalis, Bifidobacterium Longum, Lactobacillus paracasei, and Escherichia coli, respectively (Hrncirova et al., 2019).
2.6 Hazardous Chemicals
Chemicals, such as calcium carbide, sodium cyclamate, cyanide, and formalin, are potentially dangerous and they are extensively used for maturing of green tropical fruits so as to increase their shelf-life and keep them fresh (Amin et al., 2004; The daily Prothotn Alo, 2005). Dyes are used in the textile industry and the ones which are cheaper are used for coloring fruits, vegetables, beverages, soft drinks, popular sweetmeats, confectioneries to attract the customers (Billah, 2007). Formalin preservative is commonly used in labs to prevent internal decomposition of various animal samples, but fishmongers are using the same chemical to preserve fish for the very same reason (Amin et al., 2004; Rashid, 2007b; Ullah, 2005). If such types of food are consumed, then they are responsible for causing several health disorders, such as liver and kidney failure, autism, metabolic dysfunctions, and cancer (Hossain et al., 2008; Billah, 2007; Kumar et al., 2019; Azad and Ahmed, 2016; Mohammad et al., 2018).