Keywords

5.1 Introduction

One of the major healthcare concerns for mankind in the modern era is foodborne pathogens causing severe illness and deaths worldwide. There is an increased awareness among people worldwide about food safety. Food safety has become a major health concern globally as foodborne diseases have outspread in both developing and developed countries to alarming levels (Zhao et al. 2014). The increased globalization of food supplies due to cross-country trades has made food safety as the most vital concern (Lan et al. 2017). Unhealthy and unhygienic food can cause various dreadful diseases eventually leading to deaths (Sharma et al. 2015). The current worldwide situation from a health perspective is dire. Currently, the most significant food safety concerns are caused by the consumption of contaminated food. Foodborne pathogens affect food safety at various stages including food manufacturing, handling, food distribution, and finally the consumption by the customers. Thus, monitoring and real-time detection of food contaminants hold utmost importance to ensure the availability of risk-free and contaminant-free foods. The current global situation in the twenty-first century from a food safety perspective is dire. Over the years, foodborne pathogens have become a major factor contributing to society’s ill health, thus increasing the morbidity and mortality rate to alarming levels in both developed and developing countries. Foodborne pathogens are basically the microbes such as bacteria, fungi, viruses, and several other parasites that have capabilities to infect humans consuming contaminated foods. Major foodborne pathogens responsible for illness and deaths worldwide include foodborne bacteria such as Escherichia coli O157:H7, Staphylococcus aureus, Clostridium perfringens, Salmonella enterica, Campylobacter jejuni, Toxoplasma gondii, Listeria monocytogenes, other Shiga toxin-producing E. coli strains (non-O157 STEC), Norovirus and Vibrio spp., etc. (Velusamy et al. 2010; Zhao et al. 2014). Foodborne illnesses have been exacerbated by these contaminants resulting in a number of dreadful diseases and disorders such as recurring intestinal inflammation, reactive arthritis, blindness, mental disability, chronic kidney diseases, and even deaths. Yasmin et al. 2016 documented that an estimated two million deaths happen every year due to around 200 diseases and disorders like diarrhea, cancer, etc. caused due to consumption of contaminated foods. Thus, the World Health Organization has endorsed food safety as “from farm to plate (and everywhere in between) make food safe” on World Health Day, 2015. The US Centers for Disease Control and Prevention in their reports documented that in the United States, 1 among 6 people get ill per year and approximately 3000 people die because of foodborne diseases (CDC 2011). The US Department of Agriculture in their reports documented an approximate cost of $15.6 billion attributed to illnesses caused due to foodborne pathogens (CDC 2016). Foodborne pathogens are the root cause of severe health issues associated with the consumption of contaminated foods globally. Thus, the effective, accurate, and real-time detection of these contaminants is the only possible measure to ensure global food safety from a public health perspective (Arora et al. 2013). It should be taken care of to maintain proper hygiene and aseptic environment during the production, processing, and packaging of foods so as to minimize the outbreaks of diseases and disorders as a consequence of consumption of contaminated foods (Arora et al. 2013). Thus, looking at the current global food safety and health concerns, there is a desperate need for developing much efficient methods of foodborne pathogen detection besides improving the existing methods. Biosensing technologies have put forward themselves as an alternative for rapid and effective detection of foodborne pathogens. A vast range of signal transducers have been developed in the recent time to detect foodborne pathogens. Their sensitivity and results vary significantly based upon the features of the transducers and the biological materials being used as analytes. However, the development of highly sensitive biosensors for rapid, effective detection and identification of foodborne pathogens for ensuring food safety still remains a challenging task in front of global food safety organizations due to one or other technical obstacles. The purpose of this chapter is to review the biosensing methods available for quick, on-site, and efficient detection of major foodborne pathogens along with various challenges that need to be addressed as well as improvements that are required to make biosensing devices a real utility in the upcoming future for ensuring global food safety.

5.2 Current Public Health Situational Analysis in Developed and Developing Countries

The current global situation in the twenty-first century from food safety and public health perspective is dire. The world’s population explosion and the insatiable quest for advancement by mankind have brought about very grave consequences on man’s livelihood. A continuous surge in the world population has led to a huge strain on the available societal food resources. This has been exacerbated by the rapidly increasing populations especially in developing countries. In developing countries, the emergence of slum areas in the periphery of major urban cities has led to an increase in the levels of poverty, poor living conditions, illiteracy, unemployment, crime, violence, alcoholism, substance and drug abuse, prostitution, and smoking, thus contributing to society’s ill health. The excessive pervasiveness and recurrence of foodborne diseases worldwide especially in developing countries clearly suggest that food safety concerns need to be addressed. Thus it becomes imperative to ensure quick, effective, and on-site detection of foodborne pathogens so as to minimize their prevalence (Zhao et al. 2014). Thus, in this context, there has been a continuous demand for the development of efficient and quick detection methods for the detection of foodborne pathogens from a global public health perspective. A significant number of microorganisms have been reported with the ability to generate toxins responsible for causing foodborne illnesses. These include microorganisms such as E. coli O157, S. aureus, Bacillus cereus, Clostridium botulinum, C. perfringens, Vibrio cholera, etc. (Fusco et al. 2011). Communicable diseases and mental health issues may rank high among the illnesses. It is not uncommon to confront cases of diarrheal diseases, malaria, respiratory infections such as tuberculosis, HIV/AIDS, psychosis, depression, and suicide. On the extreme end of the continuum, in the developed countries, are the noncommunicable diseases such as diabetes, cardiovascular diseases, and cancer. These usually come about due to consumption of contaminated foods and contaminated water. The same diseases are also gaining prominence and recognition in developing countries especially among the middle and upper classes.

The current dilemma is to strike a balance between feeding the majority of the increasing population on available food sources and worrying about the possible after effects of consuming the foods if they are having one or the other forms of foodborne pathogens.

5.3 Technologies Available for Detection of Foodborne Pathogens

The extremity and recurrence of foodborne diseases occurring as an after effect of consuming contaminated foods have made it inevitable for the scientific communities worldwide to develop the technologies for quick, efficient, accurate, and on-site detection of major foodborne contaminants even at extremely low levels. Foods contaminated with pathogens have become a major concern worldwide as food safety has a direct interrelationship with economy and society. Some of the available technologies that can be employed for the detection of foodborne pathogens are enzyme-linked immunosorbent assays, microarray-based techniques, and methods based on polymerase chain reactions along with conventional methods of detection. These technologies can be an answer to the food safety issues faced by most of the developing countries which are currently struggling to feed the majority of their population in the wake of limited food availability, changing weather patterns, erratic rains, and land degradation and limitation. However, majority of these methods are time-consuming. The duration of time taken varies from hours to several days to give an output in the form of result. Thus, to overcome these shortcomings, detection based on biosensors plays a pivotal role in quick and effective detection of food contaminants. Biosensing technologies have emerged as an effective and rapid detection method and have extended their utility in a wide range of areas that include food safety, environmental monitoring, and clinical studies. Biosensing devices are reckoned as highly efficient detection methods due to properties like high sensitivity, specificity, quickness, applicability in various fields, and cost-effectiveness (Thakur and Ragavan 2013; Singh et al. 2020). Advances and developments in biosensing technologies have significantly improved the quality of life as they have the abilities to detect even minute levels of analytes under question (Arora et al. 2013). Foodborne pathogen detection using biosensing technologies has attained significant importance in the food sector for ensuring food safety. Biosensors possess the ability to detect low levels of pathogens and toxins making the foods highly contaminated. Biosensing methods possess certain properties like real-time detection, on-site detection, high sensitivity, selectivity, etc. which makes this technology advantageous over conventional methods of foodborne pathogen detection. These salient features give an indication of biosensing technology being used as stand-alone devices for foodborne pathogen detection in the near future (Zhao et al. 2014).

5.4 Biosensors for Detection of Foodborne Pathogens

Biosensor devices for foodborne pathogen detection in general possess as minimum as three elements which include a biological capture molecule, a measure for converting the interaction between capture molecule and target into a detectable signal, and a readout (output) system (Lazcka et al. 2007; Velusamy et al. 2010). Methods such as enzyme-linked immunosorbent assays and those based on polymerase chain reaction are considered as quick detection methods. However, these methods take several hours to days for reaching at some kind of interpretations and results (Velusamy et al. 2010). The urgency for development of highly sensitive, quick, proficient, and accurate detection methods has paved a way for the development of biosensing technology. Biosensors are basically the sensing devices which can be utilized for analyzing and detecting the substances (analytes) in question by translating a biological response to a detectable signal (Velusamy et al. 2010). Biosensing devices comprise of a biological sensing element coupled to a transducer which translates the biological response to a measurable signal. Biosensors fulfill the requirements of desired features of high sensitivity, rapidness, real-time detection, and economic analysis of analyte under investigation. Biosensor devices are portable, offer on-site detection, and possess the ability for both on-site and in laboratory detection of multiple pathogenic organisms. These characteristics make biosensors highly advantageous over other available technologies of foodborne pathogen detection which otherwise would take several hours for their detection. The abovementioned advantages of biosensing technology have made it possible to ensure correct and on the spot detection of foodborne pathogens present (if any) before consuming the food (Rasooly and Herold 2006). Different biosensors work on different fundaments of analyte detection. Overall sensitivity of a biosensor device relies upon the characteristics of transducer and upon the types of biological materials utilized as biorecognition element for analysis (Palchetti and Mascini 2008). Different biological substances which are used as biorecognition elements in biosensor devices include antibodies, peptides, nucleic acids, bacteriophages, aptamers, etc. Some biosensors utilize labeled probes or reagents for analyte detection (Bhunia et al. 2010). The performance of a biosensor device is evaluated by assessment of parameters like sensitivity, specificity, selectivity, rapidness in detection, size of device, ability to manufacture on large scale, and cost factor (Arugula and Simonian 2014). An ideal biosensor device must possess the ability to analyze undefined samples within seconds and must have the capability of simultaneous detection of multiple analytes. Biosensors have been developed and applied for the detection of various foodborne pathogens (Table 5.1) including Escherichia coli O157:H7, Staphylococcus aureus, Bacillus, Salmonella, Listeria monocytogenes, and Cryptosporidium as well as various microbial toxins such as staphylococcal enterotoxins and mycotoxins (Asiello and Baeumner 2011).

Table 5.1 Foodborne pathogen detection using different biosensors
Full size table

5.4.1 Optical Biosensors

Optical biosensors present themselves as a sturdy alternate to conventional methods of analysis on the basis of characteristics like high specificity, high sensitivity, relatively small size, and economic feasibility (Luo et al. 2004). Biosensing of analytes using biosensor device basically depends upon an enzymatic system, whereby the enzyme transforms the analyte in question to a product which can be either oxidized or reduced at a working electrode and maintained at a specific potential. An optical biosensor is a compact analytical device containing a biological sensing element coupled to an optical transducer which translates the biological response to a detectable signal (Dongyou 2010). Analyte detection through optical transducers offers advantages like economic feasibility and utilization of electrodes which are biodegradable. Optical biosensing technology can be further classified into various subclasses on the basis of a number of phenomena like fluorescence, phosphorescence, chemiluminescence, refraction, absorption, reflection, dispersion, etc. Over the past few years, several types of optical biosensors have been developed for quick, efficient, accurate, and real-time detection of various foodborne pathogens and toxins in foods before their consumption (Velusamy et al. 2010).

5.4.2 Electrochemical Biosensors

The underlying basic principle in the operation of electrochemical biosensors is concerned with their abilities of detecting distinct molecules. Electrochemical biosensors are specifically utilized for detecting biomolecules like glucose, hybridized DNA, DNA-binding drugs, etc. The electrochemical biosensing technique involves production or suppression of detectable electrons or ions by distinct chemical reaction types (Kovacs 1998). The electrochemical biosensing method of pathogen detection is transduction-based systems which have been utilized for identification and quantification of various foodborne pathogens. These biosensors can be further classified into potentiometric, conductometric, amperometric, and impedimetric types on the basis of the phenomenon in observation such as potential, conductance, current, and impedance, respectively (Velusamy et al. 2010). Electrochemical biosensors can be classified into amperometric, potentiometric, impedimetric, and conductometric responses, based on observed parameters such as current, potential, impedance, and conductance, respectively (Velusamy et al. 2010). Pedrero et al. 2009 reported that electrochemical biosensors principally utilize electrochemical impedance spectroscopy as a method of transduction for simultaneous detection of multiple foodborne pathogens. Biosensors based upon impedance spectroscopy measure the deviations in the electrical attributes of bacterial cells (coupled to or attached to the electrodes) for detecting foodborne pathogens (Yang and Bashir 2008).

5.4.3 Piezoelectric Biosensors

Piezoelectric biosensors utilize immensely sensitive piezoelectric crystals which possess the abilities of detecting even minor deviations in mass. There are two main types of mass-sensitive biosensors: bulk wave devices and surface acoustic wave devices. Piezoelectric crystals start vibrating at a particular frequency upon applying an alternating current with a fixed frequency. This specific frequency at which piezoelectric crystals vibrates depends upon the mass of the crystals along with the fixed electrical frequency. Piezoelectric biosensors have been extensively utilized for pathogen detection, and their performances in studying the affine interactions have been immensely referred.

5.4.4 Immunosensors

Immuno-biosensors basically rely on antibody-antigen-specific interactions. Their work involves detection of antigen binding to antibody by reaction onto the surface of a transducer which in turn translates changes in the surface parameters to a measurable electric signal (Gomez et al. 2010). The real-time measurement of immunological reactions is rather arduous due to the difficulty in the diffusion of antigen onto immobilized antibodies especially in cases of extremely low level of contaminants. However, a majority of immune biosensors generate results within 20–90 min range which is closer to real-time detection as compared to other conventional methods of pathogen detection.

5.5 Future Prospects

The conventional methods of foodborne pathogen detection although have good sensitivity are time-consuming when it comes to practical applicability. This time taken for giving output in the form of results varies from hours to days. The need of the hour is the development of a technology that fulfills the requirements of an ideal pathogen detection method. Thus to overcome these limitation, new technologies are required in terms of efficiency, accuracy, ability to perform on-site detection in real time, and economic feasibility. Biosensor technology is one such method that has overcome the limitations of conventional methods to significant extents. A vast range of signal transducers have been developed for the detection of foodborne pathogens. Even though biosensing technology holds enormous potential for foodborne pathogen detection, several challenges still need to be addressed to make the biosensor technology a real utility in ensuring global food safety. These challenges include factors like being able to perform in the long run, ease in use, cost-effectiveness, access to common people, increasing the sensitivity, increasing the pathogen detection limit, and development of transducers able to detect multiple pathogens in one food sample in real time. The future of biosensing technology will depend upon the applicability and suitability of the biosensors in the long run and the ability to provide quick and accurate results for on-site and real-time detection and identification of foodborne pathogens so as to meet the consumer demand for safe foods as well as for ensuring global food safety. However, despite the broader applicability and the great potential of biosensing technologies, there is still a great chance for further developments in the near future.