Case Studies in Novel Food Processing Technologies

Innovations in Processing, Packaging, and Predictive Modelling

C J Doona

• Publisher: Woodhead Publishing
• Year: 2010
• Print ISBN: 9781845695514
• eBook ISBN: 9780857090713
• Topic: Technology & Engineering
• Subtopic: Food Science
• Index: Technology & Engineering

Novel food processing technologies have significant potential to improve product quality and process efficiency. Commercialisation of new products and processes brings exciting opportunities and interesting challenges. Case studies in novel food processing technologies provides insightful, first-hand experiences of many pioneering experts involved in the development and commercialisation of foods produced by novel processing technologies.Part one presents case studies of commercial products preserved with the leading nonthermal technologies of high pressure processing and pulsed electric field processing. Part two broadens the case histories to include alternative novel techniques, such as dense phase carbon dioxide, ozone, ultrasonics, cool plasma, and infrared technologies, which are applied in food preservation sectors ranging from fresh produce, to juices, to disinfestation. Part three covers novel food preservation techniques using natural antimicrobials, novel food packaging technologies, and oxygen depleted storage techniques. Part four contains case studies of innovations in retort technology, microwave heating, and predictive modelling that compare thermal versus non-thermal processes, and evaluate an accelerated 3-year challenge test.With its team of distinguished editors and international contributors, Case studies in novel food processing technologies is an essential reference for professionals in industry, academia, and government involved in all aspects of research, development and commercialisation of novel food processing technologies.- Provides insightful, first-hand experiences of many pioneering experts involved in the development and commercialisation of foods produced by novel processing technologies- Presents case studies of commercial products preserved with the leading nonthermal technologies of high pressure processing and pulsed electric field processing- Features alternative novel techniques, such as dense phase carbon dioxide, ozone, ultrasonics, cool plasma, and infrared technologies utilised in food preservation sectors

1

Non-thermal food pasteurization processes: an introduction

P. Chen, S. Deng, Y. Cheng, X. Lin, L. Metzger and R. Ruan, University of Minnesota, USA

Abstract:

The food industry and consumers have significant interest in nonthermal pasteurization processes because they offer better quality and nutrition retention and are more energy efficient than traditional thermal processes. Non-thermal processes may also create value-added products and open new market opportunities. This chapter will provide an overview of several non-thermal processes with the potential for producing valued-added foods, including pulse electric field (PEF), high hydrostatic pressure (HHP), ionizing irradiation, UV light, non-thermal plasma (NTP), and concentrated high intensity electric field (CHIEF). Their respective mechanisms for inactivating microorganisms, technical characteristics, and current status of the application of these processes will be discussed.

Key words

non-thermal pasteurization

pulse electric field (PEF)

high hydrostatic pressure (HHP)

ionizing irradiation

ultraviolet (UV) light

non-thermal plasma (NTP)

and concentrated high intensity electric field (CHIEF)

1.1 Introduction

Many consumers enjoy the robust, natural flavor and taste of unpasteurized/raw apple juice or cider. However, due to associated outbreaks of foodborne illnesses, unpasteurized fruit juice has become mostly a thing of the past. In 1998, FDA adopted a regulation that forced fresh juice processors to either pasteurize their products to inactivate 5 logs of pathogenic microorganisms or attach the label ‘WARNING: this product has not been pasteurized and, therefore, may contain harmful bacteria which can cause serious illness in children, the elderly and persons with weakened immune systems’ (FDA, 1998). In 2001, FDA adopted the ruling to implement the Hazard Analysis and Critical Control Point (HAACP) procedures for the Safe and Sanitary Processing and Importing of Juice, effective February, 2002 (FDA, 2001). Apple juice production and consumption in the United States has been in decline for many years, which puts tremendous pressure on the fruit juice industry to boost consumption, while ensuring safety and retaining freshness and nutrients. In order to retain full flavor of their products, some companies have adopted a tight sanitation and HACCP program to achieve a 5-log reduction in production of unpasteurized apple juice/cider. A few producers even accept the warning label on some products, and others have combined ‘light’ or ‘ultralight’ pasteurization with HACCP, thus minimizing the decrement of flavor. However, most of the companies prefer to choose pasteurization to assure the safety of their products.

Methods of pasteurization have changed from conventional treatments used in the past. Until recently, thermal processes, especially ultra high temperature (UHT) and high temperature short time (HTST) have been the most commonly used methods in the food industry to increase shelf-life and maintain food safety. However, studies have shown that heat degrades product color, flavor, and nutrients because of protein denaturation and the loss of vitamins and volatile flavors (Processors, 1998). Therefore, there is increasing demand for alternative methods for fresh food pasteurization that ensure safety while decreasing product degradation.

Non-thermal methods provide such an option because they reduce overprocessing to result in more fresh-like foods featuring greater retention of color, flavor, and nutrients. Currently, there are several methods having the ‘nonthermal’ claim for liquid food product pasteurization: (1) pulse electric field (PEF), (2) high hydrostatic pressure (HHP), (3) irradiation, and (4) UV light. Two emerging processes; namely, cold or non-thermal plasma (NTP), and concentrated high intensity electric field (CHIEF), are under development. In this chapter, we will provide a brief description of each of their mechanisms of microbial inactivation, technological characteristics, and current application status of these processes. Some of these alternative processes have been studied extensively for at least two decades, but none of these alternative processes is in large-scale commercial practice for fruit juice and milk pasteurization due to technical issues or, more often, economic disadvantages. The high resistance of enzymes and bacterial spores to these processes is a major problem. Efforts are needed to improve these processes or develop new processes. It is also suggested that combinations of these processes and other methods, which are termed ‘hurdle technology’, may present potential benefits and practical uses of these processes.

1.2 Pulsed electric field

High intensity pulsed electric field (PEF) processing (Fig. 1.1) involves the application of short pulse (1–10 μs) of high voltage (typically 20–80 kV/cm) to food materials located between two metal (usually stainless steel) electrodes (Qin et al., 1996; Vega-Mercado et al., 1997). Studies of exposure of microorganisms to electric fields have indicated that electric field can cause changes to cell membranes (Pothakamury et al., 1997; Barbosa-Cánovas et al., 1999). When a voltage is applied to a cell, a sufficiently high transmembrane potential is induced across the cell membrane, causing the membrane to rupture (direct mechanical damage, the electric breakdown theory), or destabilizing the lipid and proteins layers of cell membranes, resulting in pores (electroporation theory). The damaged cell membrane loses its selective semi-permeability, which allows water to enter the cell, and results in excessive cell volume swelling, and ultimately leads to cell rupture and inactivation of the organism. Some studies have provided microscopic evidence to support this theory (Harrison et al., 1997; Calderón-Miranda et al., 1999). Recent studies showed increased membrane permeability after PEF treatment (Aronsson et al., 2005; García et al., 2007).

Fig. 1.1 Pulsed electric field (PEF) process schematic diagram.

PEF has been used to process fruit juices (Jin and Zhang, 1999), dairy products (Reina et al., 1998), and eggs (Dunn, 1996). Research found that apple juice processed with PEF at 50 kV/cm, 10 pulses, pulse width of 2 μs, and initial temperature controlled at 45 °C had a shelf-life of 28 d compared to a shelf-life of 21 d for untreated, fresh-squeezed apple juice. PEF processed apple juice showed no physical or chemical changes in ascorbic acid or sugar contents. PEF also demonstrated advantages over heat pasteurization for orange juice in terms of vitamin C, flavor, and color retention without inducing sedimentation like thermal treatments (Yeom et al., 2000). A majority of studies involving PEF focused on its effect on milk and dairy products due to the importance of the dairy industry. Model aqueous suspensions similar to milk ultrafiltrate, pasteurized milk, and raw milk have been used in those studies. Different levels of microbial inactivation were achieved with PEF treatment depending on the type of samples, type of microbe, the field strength, and the number of pulses applied during the process (Martin et al., 1997; Pothakamury et al., 1997; Bai-Lin et al., 1998; Qin et al., 1998). The inactivation of enzymes by PEF is limited, although the effect of PEF on enzymes has been shown to vary with the electric field intensity, the number of pulses applied during the process, and the intrinsic characteristics of the enzyme (Bendicho et al., 2003; Kambiz et al., 2008).

There are a limited number of studies on the effect of PEF on the nutrients and sensory quality of milk. Bendicho et al. (2002) found that PEF-treated milk showed no changes in the contents of most vitamins, except for ascorbic acid (Vitamin C), which reduced slightly. Grahl and Märkl (1996) reported that the ascorbic acid content of milk was reduced considerably (90%, data not shown) by PEF treatment, whereas the content of vitamin A and the flavor showed no significant changes. Zulueta et al. (2007) reported that high intensity PEF treatment slightly changed the amounts of total fat, saturated fatty...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor contact details
• Woodhead Publishing Series in Food Science, Technology and Nutrition
• Preface
• Chapter 1: Non-thermal food pasteurization processes: an introduction
• Part I: Case studies in high pressure and pulsed electric field processing of food
• Part II: Case studies in other novel food processing techniques
• Part III: Case studies in food preservation using antimicrobials, novel packaging and storage techniques
• Part IV: Innovations in advanced food processing techniques and predictive microbial models: case studies
• Index