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Ultraviolet light (UV, UVC) disinfection is a well-established technology for air, water, and surfaces treatments. In the last decade, UV technology found more applications in food production chain because this is economic, effective, and versatile dry processing technology that can potentially improve safety and preservation quality of different categories of foods. Traditional way of generating UVC light is using high-voltage arc-discharge mercury or amalgam lamps that can generate photons solely at 253.7 nm. Light-emitting diodes or LEDs are semiconductor devices that can also emit UVC light, but depending on the material properties of the diodes, they can emit photons at multiple wavelengths in the UV range between 255 and 365 nm. The germicidal effects of UV LEDs against bacteria, viruses, and fungi already have been demonstrated and reported along with the first applications for disinfection of air, water, and surfaces made for the “point of use” integration. Despite the fact that there are no commercial applications in food production yet, the UV LEDs are the next wave in the LED revolution that can bring numerous advantages for food processing, safety, and plants facilities disinfection. This chapter will present the introduction in basics of LEDs technology and will discuss the unique advantages of this technology for food safety applications. Also, economical, energy saving, and sustainability aspects of UV LED applications are introduced.

Safety of food processing facilities and finished products can greatly benefit from application of UV light technologies to control microbial hazards through treatments of air, nonfood and food contact surfaces, ingredients, packaging, raw and finished products. Low-pressure lamps emitting light at 253.7 nm are currently approved as a main radiation sources for treatment of juices, surfaces, or vitamin D generation with the limitations in terms of ozone production. Currently, UV LED technology is quickly extending in the UVB and UVC germicidal range as alternative to traditional UV lamps. Despite the low efficiency of UVB and UVC LEDs (approximately at 4%), LEDs are on growing trend and UVA LEDs are already being incorporated into point-of-use units to serve the defense and outdoor industries and tested for water treatment. Food safety application is the next step of UV LED adaption by industry. This chapter will review the germicidal action of UVA, UVB, UVC, and blue light, existing research, and first reported application of UV LEDs against foodborne pathogens at multiple wavelengths. Understanding of bacterial action spectra is also discussed to provide basis for optimization of the most effective treatment using single or wavelengths combinations. Considerations for UV LED treatment of fresh produce with some reported effects on quality and nutritional attributes are included.

The basic of light-emitting diodes (LEDs) technology and manufacturing features will be presented in this chapter. The fundamental principles of light emission by semiconducting materials, design of LEDs chips and types of packages, requirements to LEDs system are discussed for better understanding of this new light technology. The differences and application areas in production and postharvest processing of fruit and vegetables of visible and UV LEDs are also included to better understand LEDs potential in food industry.

At present, there are a few techniques based on the unique properties of light to treat a variety of foods and food-related microflora that are explored for preservation operations and can result in improved quality, nutrition, and desired functionality. This includes continuous ultraviolet (UV)-C lamps and light-emitting diodes, pulsed UV (PUV) light, and pulsed light (PL). Each light-based technology is characterized by specific emission spectra, inactivation mechanisms, and unique advantages and disadvantages that lead to applications differences. This chapter will summarize the basics of generation and emission of PL and PUV, mechanisms of microbial inactivation, effects on quality and nutrition, and existing applications with emphasis on nutritional and other quality effects. Available light sources and commercial equipment, the pros and cons of the PL and PUV for preservation and improving quality and functionality of food and beverages are presented.

The light technologies have been slowly taking the niche for surfaces disinfection and preservation of solid and liquid foods as a mild heating or solely nonthermal and nonchemical treatment.

Application of continuous and pulsed ultraviolet (UV-C) and pulsed light technologies for disinfection of food contact services and food surfaces is discussed as a novel nonthermal purely physical method. The features and efficiency of commercially available sources of continuous and pulsed light, such as mercury lamps, light-emitting diodes and pulsed UV-C, and light sources, are reviewed. The factors affecting the UV disinfection efficiency on the food and contact surfaces are presented along with the principles of light-based disinfection process design.

The ultraviolet (UV) light technology has been slowly taking its niche for decontamination and preservation of liquid foods and beverages as a truly nonthermal and nonchemical treatment. Even though the term “irradiation” is frequently used for this treatment, UV is also considered as a light. UV light is safe to use; an ecologically clean technology because it is free of chemicals, waste effluents; and it typically does not produce by-products and can provide energy and cost savings opportunities for food manufacturers. Recently, commercial UV systems have been developed using thin film laminar, turbulent or complex vortexes flow patterns that are capable to deliver efficient treatment to control pathogenic, and spoilage contaminants in many categories of fluid food products, ingredients, drinks, and soft beverages. The existing and potential applications of UV light include juice products, milk, sugar syrups, liquid eggs and egg components, wine, and protein ingredients. This publication summarizes the recent knowledge and essential information on UV light technology for safety and extension of shelf life of a variety of fluid food products and beverages.

Ultraviolet (UV-C) light technology at 253.7 nm is a nonthermal method to pasteurize and/or extend shelf life of juices, sugar syrups, and heat-sensitive compounds and is accepted by consumers and regulators. In addition to the ability to inactivate microorganisms in these products, UV-C light can destroy some mycotoxins and undesirable chemicals (food processing contaminants) such as furan and its derivatives that can be formed in foods during thermal treatment and storage. This article discusses the effects of UV-C light at multiple wavelengths of 222, 254, and 282 nm on destruction of mycotoxin of patulin in apple juice and cider. In addition, the reported effect of UV-C treatment on furan formation in major components of apple cider such as sugars (fructose, sucrose, and glucose) and organic acids (mainly malic acid) are summarized. The ability of UV-C light at 254 nm to reduce concentrations of hydroxymethylfurfural (5-HMF) in fructose syrups is presented.

UV light radiation is similar to visible light in all physical aspects, except that it does not enable us to see things. Different wavelengths of electromagnetic spectra cause different types of effects on people. For example, gamma rays are used in cancer therapy to kill cancerous cells and infrared light can be used to keep you warm. UV light has shorter wavelengths (higher frequencies) compared to visible light but has longer wavelengths (lower frequencies) compared to X-rays. Some UV exposure is essential for good health. It stimulates vitamin D production in the body. In medical practice, UV lamps are used for treating psoriasis and for treating jaundice in newborn babies.

The inactivation of essential groups of food microorganisms by pressure, their resistance to pressure, and factors to consider in order to develop preservation process using HPP are described in this section. The determination of inactivation rate parameters such as D- and z-values is given to characterize microbial reduction under pressure.

The advantages of UV processing for the products that were recently commercialized are discussed. This includes fresh juices, wines, raw and cheese milk, sugar syrups, whey proteins, and whole eggs and eggs components. Each application is described from the point of process objective, unique value-added advantages and effects of UV light on quality and nutritional parameters. The chapter provides a perspective of UV based non-thermal processing solutions for food manufactures.

The chapter discusses a number of commercial UV systems that have been developed and validated for different categories of low UVT and opaque fluid food products. The advantage of laminar, turbulent, static surface refreshment flows and dynamic vortexes flow is presented. The examples of commercial UV systems such as CiderSure, Aquionics, SurePure and MicroTek Processes are given along with the ranges of their application in food industry.

This section reviews a range of fluid parameters such as physico-chemical (pH, water activity, viscosity); optical characteristics (absorption coefficient, absorption spectrum and penetration depth), processing parameters (UV fluence, UV dose, flow pattern) that can critically effect efficiency of UV treatments. The examples of measured parameters for juice products, the effect of wavelength in UVC range are presented.

Minimizing microbial contamination on the surface of food products is a basis for longer shelf life and improved safety. Both cUV and PL treatments have been tested for inactivation of spoilage and pathogenic microflora on the surface of a wide variety of solid foods. Chapter 5 will briefly review reported results when UV light was used to reduce microbial contamination on the surfaces of fruits, fresh-cut produce and meat products both raw and packed ready to eat, eggs, and seafood. The analysis of the available information will provide a perspective of commercial feasibility of cUV and PL treatments as processing aids for the surface treatment of different categories of raw and finished products. The examples of commercially available UV units for surfaces treatment are presented.

The practical approaches for the evaluation of energy consumption for UV treatments of fluids are presented along with the examples of calculation of applied energy for three types of commercial UV systems. This includes laminar, turbulent and Dean flow system. The energy calculation has been made for pasteurization process of apple juice that achieves 5 log microbial reduction. The concept of electrical energy per order is used and demonstrated the electrical energy saving for turbulent flow systems.

Application of HPP for raw and RTE meat and poultry products, fruits and vegetable processing, cold pressed juices, seafood and dairy categories are discussed. The range of operating pressures to be applied to achieve shelf-life extension, pasteurization, and nonthermal extraction treatments of different categories of finished and raw seafood products are presented.

The section is focused on HPP process parameters for operations of pasteurization and sterilization. The differences in HPP cycles are discussed. The definitions of HPP parameters are given with the detailed effects of the critical product parameters and ranges of their variations. The impact, importance of proper documentation, and control in regards to HPP efficacy is discussed.

The packaging aspect of HPP is discussed. The requirements for plastic packaging materials and their compatibility with HPP technology are detailed along with the packaging design and a brief review of reported studies.

This chapter will review factors affecting interaction of UV light with the surfaces of solid materials. The approaches on how to determine the required and applied UV doses on the surfaces along with the definition of the UV decimal reduction dose or D-value are briefly discussed. Possible environmental effects of UV lamps applications at the food plants and vice versa effects of food plant environment on the design and applications of UV sources that need to be considered are reviewed. The current regulatory status of the approved UV treatments of food products is presented.

The chapter provides a brief overview of available sources of UV light such as mercury, amalgam and eximer lamps and discusses their technical characteristics that are important to compare electrical and UV efficiency and their advantages for various applications. The described UV sources have been successfully tested for treatment of low UVT fluid ingredients, drinks and beverages.

This section discusses the photochemical effects caused by UVC light to cause microbial inactivation along with mechanisms of dark repair and photo-reactivation; the approaches of how to quantitatively characterize linear and non-linear inactivation kinetics of organisms caused by UV light, and the effects of various wavelengths on inactivation in apple juice. The DUV decimal reduction dose and δ scale parameters are defined to characterize UV resistance of different groups of microorganisms. The examples of experimental studies are given to illustrate the importance of correct determination of kinetic parameters for UV process development in opaque fluids.

The chapter presents new processing opportunities when HPP is combined with low temperatures in freezing and thawing operations for premium meat and fish products. Additionally, HPP potential in developing meat products with reduced sodium chloride content is discussed.