Role of Biosensors in Quality and Safety of Dairy Foods

ABSTRACT

The dairy industry is one of the many industries that are concerned with the occurrence of pathogenic bacteria, where a pathogenic microbe further leads to a destructive influence on human health. The food-borne outbreaks of diseases from bacterial pathogen contamination and chemicals are veiy common around the world. Improper pasteurization and even incidents of the presence of contaminating microbes after pasteurization occurs most often. Daily products are consumed in large volumes so infrequent contamination of commercially distributed products may end up in several sicknesses. Biosensors can help in the analysis of food quality. Biosensors facilitate to hold out the procedures that are selective, sensitive, rapid, cost-efficient, and moveable. These devices are excellent substitutes for the current conservative techniques. The current trend is a biosensor application within the food processing discipline. The fundamental principle, biosensor development, history, and their classification are discussed in this chapter. Primary contaminants in food processing can be identified with the use of biosensors.

INTRODUCTION

One of the primary concerns in human health is food safety and food-bome infections. Although the level of food safety has improved the food-borne outbreaks from microbial spoilage, chemicals, yet these are still frequent [34]. In food spoilage, poultry (18%), dairy (18%), and beef (13%) commodities are primary culprits. The dairy industry has been a common source of health complaints (14%) and deaths (10%) from spoiled dairy products. The process of pasteurization removes most of the pathogens in milk and milk products, however, sometimes inappropriate pasteurization and chances of contamination after pasteurization usually occur [24].

Dairy products are consumed on a large scale around the globe, which may lead to infrequent spoilage of commercially distributed daily products resulting in various illnesses [25]. In the daily industiy, a large number of outbreaks of diseases and illnesses are associated with Campylobacter spp. in raw milk [17]. In many of the industrialized countries, 30% of the total population every year suffer from food-borne diseases (FBD) mainly associated with L. monocytogenes, Campylobacter, E. coli 0157:H7, Salmonella, S. aureus, B. cereus, E.faecalis, etc., compared with other uncommon food- borne bacterial pathogens [2, 6].

Milk is one of the important constituents in our daily diet; therefore its assurance for quality and safety is an essential component for the welfare of humanity. Dairy producers will be benefited with products that will have consistency in organoleptic and compositional features, longer shelf-life, and most importantly safe for human consumption. These unique qualities drive to increase the use of superior grade products.

In India, the quality of milk and milk products are governed by FSSAI (Food Safety and Standards Authority of India) regulations for both microbial and non-microbial contaminants. Therefore, it is mandatory to test the daily products for the presence of pathogenic agents before transporting into the market. Presently, conventional testing methods have been used for the evaluation of microbial and non-microbial contaminants in daily products. There are shortcomings in these conventional methods, which take several days to complete the testing of products and are costly and laborious. These time-consuming processes result in the delivery of partially processed products in the market as a result of which the industiy has the only option of banning and recalling the product.

The industries are under tremendous pressure to meet the consumer requirement and there is an urgent need for substitute methods to replace conventional techniques. The alternate methods must be cheap, rapid, easy, and validated. Primary contaminants (like antibiotics, pesticides, heavy metals, bacterial pathogens) can be identified using the biosensor method in the dairy supply chain.

This chapter discusses the basic working principle of a biosensor along with its developmental history and classification.

BIOSENSORS

In the biosensor, the biochemical moiety is integrated with the transducer or electrode to produce a physical signal that is then translated to indicate the quality and safety of daily products. Procedures involving biosensors are very selective, rapid, sensitive, cost-effective, and portable. In the dairy industry, biosensor devices are excellent substitutes for the existing conventional techniques [29].

13.2.1 TYPES OF BIOSENSORS

The types of biosensors are listed in Table 131.1.

TABLE 13.1 Classification of Biosensors

Signal Transduction

Electrochemical

Amperometric, potentiometric, Conductometric, and Impidometric

Mass Sensitive

Piezoelectric and Cantilever biosensors

Optical

Optical density, Bioluminescence, Chemiluminescence, Fluorescence, Phosphorescence, Refractive index, Surface Plasmon/Total Internal Reflection, Diffraction, and Polarization

Thermometric

Energy, exo-thermic, and endo-thermic reactions

Biorecognition Molecule

Antibodies

Monoclonal, and Polyclonal

Enzyme

Catalytic types and inhibition types

Lectin

Carbohydrate-binding proteins

Nucleic acid

Hybridization, and Low weight compound interaction

Protein

Metatropic receptors, and Ionotropic receptors

Spores

Bacterial endospores-inhibition type and germination types

Whole-cell

Micro-organisms, immune cells, and tissues

13.2.2 REQUIREMENTS OF A BIOSENSOR

The development of a biosensor requires the following features for its potential use in daily plants [28].

• Limit of Detection (LOD): Minimum concentration or analyte detection ability with least number of steps for analysis.

  • Quick Response Time and Recovery Time: Real-time monitoring and small recoveiy time.
  • Reproducibility7 of Signal Response: It should show the same reaction/signal.
  • Selectivity or Specificity7: Biosensors should have no interference with analyte having an analogous structure.
  • Stability7 and Operating Life: Biochemical and bioaffmity activity is retained for a longer period.
  • • The linearity of the response of biosensors reaction must cover the concentration range.
  • 13.2.3 PRINCIPLE OF OPERATION OF A BIOSENSOR

As shown in Figure 13.1, the transducer, which creates a physical variation associated with the biochemical or bioaffmity intercation of a ligand with an analyte has been explained in detail by Thakur et al. [29] as follows:

  • • Exo-thermic or endo-thermic reaction, i.e., enzyme thennister.
  • • Oxidation-reduction reaction, i.e., Amperometric biosensors.
  • • Change in the transducer physico-optical characteristics during biochemical or biomolecular interaction, i.e., Optical-based biosensors.
  • • Change in the oscillation of vibrating material immobilized with biomolecules, i.e., Piezo-electric-based biosensors.
Graphical representation of biosensor

FIGURE 13.1 Graphical representation of biosensor.

13.2.4 HISTORY OF BIOSENSOR TECHNOLOGY

In 1956, Leland C. Clark Jr. (the forerunner in an arena of biosensor research) published a paper on electrode to measure the oxygen concentration in the blood [7]. Later during 1967, Updike, and Hicks presented their first oxygen sensor, wherein the glucose oxidase (GOX) was immobilized on functional electrode. Guilbault and Montalvo have described an earliest potentiometric electrode for urea estimation by urease enzyme in 1970 [12]. In 1973, Guilbault, and Lubrano [11] described a platinum electrode using glucose and a lactate enzyme for the detection of hydrogen peroxide. In 1974, a heat-sensitive enzyme sensor termed ‘thermistor’ was developed by Klaus Mosbach [21].

In 1983, Liedberg used SPR technique to monitor affinity reactions in real time [18]. In 1987, MediSense at Cambridge University developed a pen-sized meter based on screen-printed enzyme electrodes for the monitoring of glucose level at home. Further, the concept was unproved into card and computer mouse-style formats, which caused a profit of USS175 million to the company by 1996.

13.2.5 CLASSIFICATION OF BIOSENSORS

The biosensor may be categorized based on the use of biological recognition mechanism or the mode of signal transduction [4].

  • By Bioreeognition/Biomoleeule: It is a biological species or a living biological system or ligand that employs biochemical reactins for recognition. It can include: nucleic acid, enzyme, antibody, proteins, lectins, bacterial spores, a cellular organelle, microorganism, whole cell, and tissue, etc.
  • • By the Transduction System: It is used to translate the biological recognition into the signal, which is measurable and can be detected and displayed.
  • 13.2.5.1 BIORECOGNITION MOLECULE

The construction of the biorecognition element forms the fundamental aspect of designing of a biosensor. Functional biological moieties having affinity and specificity include enzymes, antibodies, whole cells, and functional oligo-nucleotides [19, 26]:

  • Enzymes or Biocatalysts: These are protein molecules, which are specific to substrates, catalyze a specific biochemical reaction. In the last decade, this type of biosensor has been extensively explored. In the dairy and pharmaceutical industry, an environmental pollution control and monitoring are primary concerns [19]. In the enzyme- based optical biosensor, enzymes immobilized on solid surfaces are used to improve half-life and sensitivity. Furthermore, the use of optical transducers improves self-containment and compactness. These enzyme-based optical biosensors can control environmental pollution. Although remarkable improvements have been made to expand the quality of enzyme-optical based biosensors to extend their competences for sky-scraping selectivity, sensitivity, and response time, yet there are limitations in the detection of environmental pollution for early warning [19].
  • Antibodies: Immuno-sensors are potential tools in the area of quality and safety monitoring and diagnosis in the dairy industry exploring the specific biological interactions between specific antigen and antibody [19]. Optical or electronic transducers are used to monitor the interaction of antibody (contains two binding sites) with a particular target [8]. Hence, the antigen-antibody based immunosensor provides a highly specific interaction set-up to identify particular analyte in the food matrix. In an immunoassay, an antibody is defined by its selectivity and superiority. Therefore, it is widely known by the outcome of affinity between hapten binding to the carrier protein referred as antigen. Immunosensors are superior than enzyme-linked immune sorbent assay (ELISA), which differs with respect to its ability to regenerate and specificity. Also, there are limitations like: configuration and placing of immune cells on the exterior sensor chip are challenging [1]. The use of acids for regeneration in the antibody-based biosensor reduces the capability to recognize immobilized ligand after sensor surface reuse. This process provides firmness and consistency of an immunosensor. There is also a limit of regeneration up to several attempts, and in a repeated use, there is decrease in binding activity of ligand, which may yield inaccurate results.
  • Aptamers: -based biosensors use sequences of single-stranded DNA or RNA, respectively, which are selected by systematic evolution of ligands by exponential (SELEX) enrichment [2]. The mode of aptamer binding exploits its target selectively by folding into a tertiaiy structure [8]. The structural compatibility, piling of aromatic rings, electrostatic, and Vander Waals interfaces, hydrogen bonding, or a blend of all these effects are most common interactions of an aptamer to its target [1]. Because of their unique characteristics, aptamers serve as a useful alternative to antibodies used in immunesensors as sensing molecules [5]. Aptamers can be chemically synthesized, which minimize the batch-to-batch variations. Furthermore, chemical synthesis can also be used to modify these molecules to enhance the affinity, specificity, and stability. These molecules are also more stable, resistant to degradation and denaturation than antibodies [20].
  • DNAzvmes or Deoxvribozyuies or Catalytic DNAs: These are nucleic acids (NAs) folding into a distinct 3-D construction with specific binding pocket [33]. These catalytic DNAs are selected by iti vitro screening, made to work in the existence of a specific object. DNAzymes along with aptamers bind to a broad series of molecules, which in turn create a new class of functional NAs. [14].
  • Whole Cells: These are excellent sources to detect toxic compounds. Large number of microbe-based whole-cell biosensors have been developed, which work on the fluorescing ability of the molecule to identify toxicity and pollutants [23].
 
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