1.1 INTRODUCTION
The never-ending consumer demand for safe, convenient, and quality food products has urged the food industries to hunt for novel food processing technologies. The consumer’s preference for minimally processed foods is witnessing exponential growth. This demand has diverted the research and developments in public-funded research institutes as well as in industries towards the development of novel non-thermal technologies, which tend to maintain the fresh-like properties of the food products along with its extended shelf-life. Some of the non-thermal technologies are high-pressure processing (HPP), PEF, irradiation, ozone, cold plasma, and ultrasound [8, 16, 37].
The efficient and economical production of quality food products are now becoming the top priority of food industries. At the same time, the industries have started adopting innovative techniques, which are eco-friendly and utilize minimal energy and water. One such emerging non-thermal food processing technique is high-pressure processing (HPP) [6, 27, 29, 46, 64, 71, 74, 102]. Though the technology was introduced a century back, yet the commercial and consumer acceptance has happened only during recent years. The technology has been widely adopted by the food industries in United States, South Korea, Japan, and Spain, accounting for sales of about US $10 billion [47].
HPP technology allows the extension of the shelf life of the product without altering much of its physical, biochemical, and nutritional characteristics. Since the food quality is directly related with the biochemical, nutritional, and microbial attributes of the foods, HPP guarantees the production of high-quality food products [82]. The consumer’s perception of high-quality foods depends on the fresh-like properties of the food even after processing. HPP is often termed as cold pasteurization technology, wherein the pre-packed food material either in the solid or liquid state is exposed to 300–600 MPa for a shorter holding time [35, 83]. However, the process does not entail any heating source, yet the increase in pressure results in heat generation in a minimal amount that does not affect the food quality. This attribute has made the HPP processed products comparable to the unprocessed products [51, 96].
High-pressure food processing was initially experimented in the University of West Virginia, USA [44] for extending the shelf life of milk for a period of 4 days. The high-pressure of about 600 MPa was applied to milk for one hour at room temperature. During the 1980s, the research conducted at the University of Delaware (USA) showed the reduction of microbial and enzymatic activities of high-pressure processed foods without much alteration of basic natural compositions. Unlike the thermal treatments, HPP deactivates microorganisms of the food and has the ability to produce fresh-like products with better functional properties [2]. This unique property of HPP led to the widespread development of this technology by food industries across many countries. Thereon from the 1990s, the technology started gaining momentum, and many Japanese programs on HPP created awareness among the research institutes, corporate of different countries.
During 1988–1993, a research consortium was formed by the Japanese food industry for the commercialization of HPP. It was followed by the US Army initiative to conduct research on HPP during 1993–1995 by signing a joint contract with Professor Hoover of the University of Delaware and Professor Farkas of Oregon State University. HPP studies were widened for the processing of various value-added fruits and vegetable products (like juices, salad dressings, sauces, jams, and jellies) [43, 70]. In addition, innovations and interventions were made in HPP towards raw ingredients aiming at advanced and fresh-like sensorial and functional properties [12].
The high-pressure processing technology entails sealing the sample within the packaging material and placing it within a high-pressure chamber. The packaging material must withstand the sample being exposed to higher pressures of about 300–600 MPa. The adhesion between the multi-layered pouches needs to be highly stable to contain the sample during processing. Even hairline leakages in the package could cause a threat to the microbial contamination of the product [50].
Packaging materials selected for HPP should be highly impermeable to water vapor, oxygen, and moisture and are able to retain the color, fresh flavor, and aroma of the contained sample. The heavy capital cost of the pressure vessel and the allied components of the HPP set up had resulted in the limited commercial success of this technology [10]. However, with the advancement of science and technology, the equipment cost has been reduced, and commercialization has started up in different countries. More than 230 HPP machines have been installed globally for producing HPP food products during 2012. The first commercially processed HPP food was released by Japan in 1990 by Meidiya [97]. Currently, commercial HPP food products, namely ready-to-eat meats and meat products, fruit juices, and jams are available in U.S.A., France, Italy, Portugal, Spain, and Poland.
The US Department of Agriculture (USDA) and US Food and Drug Administration (FDA) has recognized HPP as a safe post-packaging pasteurization technology for shelf-stable high acid foods provided the processing is achieved targeting the E. coli O157:H7 as an indicator strain. FDA in 2009 had approved HPP for the manufacturing of low acid foods and formulated suitable regulations. Since 2004, the Canadian markets have witnessed the HPP processed foods. Since then, Health Canada assessed various HPP processed foods, such as applesauce, fruit juices, ready-to-eat meat products, etc. Initially, the European Commission (EC) had considered the available legislation on novel foods for HPP food products, b...
