Essential oils are concentrated extracts of various plants that contain their original flavor and aroma. They can be extracted using a variety of methods, including mechanical or distillation processes. It is well established that the presence of diverse aromatic components imparts a distinct flavor to essential oil. This chapter discusses essential oils derived from the Lamiaceae family, such as rosemary, thyme, mint, and basil, in detail, including their chemical composition, the presence of various volatile and non-volatile components responsible for imparting characteristic flavor, and the various health benefits associated with essential oils. It discusses several efficient and effective techniques for extracting essential oils, including steam distillation, hydro-distillation, microwave-assisted hydro-distillation, and supercritical CO2 extraction. Finally, the chapters discuss the safety, toxicity, and regulation of essential oils, including appropriate dosage limits and an explanation of the various health issues associated with excessive essential oil consumption. The essential oil can be utilized in a variety of pharmaceutical, agro-food, and non-food applications, and it is claimed that maintaining proper storage conditions extends their shelf life.

The working population growth have created greater consumer demand for ready-to-eat (RTE) foods. Pasteurization is one of the most common preservation methods for commercial production of low-acid RTE cold-chain products. Proper selection of a pasteurization method plays an important role not only in ensuring microbial safety but also in maintaining food quality during storage. Better retention of flavor, color, appearance, and nutritional value of RTE products is one of the reasons for the food industry to adopt novel technologies such as high-pressure processing (HPP) as a substitute or complementary technology for thermal pasteurization. HPP has been used industrially for the pasteurization of high-acid RTE products. Yet, this method is not commonly used for pasteurization of low-acid RTE food products, due primarily to the need of additional heating to thermally inactivate spores, coupled with relatively long treatment times resulting in high processing costs. Practical Application: Food companies would like to adopt novel technologies such as HPP instead of using conventional thermal processes, yet there is a lack of information on spoilage and the shelf-life of pasteurized low-acid RTE foods (by different novel pasteurization methods including HPP) in cold storage. This article provides an overview of the microbial concerns and related regulatory guidelines for the pasteurization of low-acid RTE foods and summarizes the effects of HPP in terms of microbiology (both pathogens and spoilage microorganisms), quality, and shelf-life on low-acid RTE foods. This review also includes the most recent research articles regarding a comparison between HPP pasteurization and thermal pasteurization treatments and the limitations of HPP for low-acid chilled RTE foods.

This study investigated the impact of two pasteurization methods on the quality of ready-to-eat green beans during storage at 2 and 7 °C. Green beans were preheated to 45 °C, then subjected to high pressure processing (HPP) at 600 MPa, 20 min. Green beans were also pasteurized by a microwave-assisted pasteurization system (MAPS) with a minimum pasteurization value of P90 °C = 10 min. Total plate counts after the treatments were below the detection limit (< 10 CFU/g) but increased to ~ 105–6 CFU/g after 1 week at 7 °C and 4 weeks at 2 °C storage. We observed swelling in high pressure- and MAPS-treated pouches at 3 and 5 weeks of storage at 7 °C, respectively, along with a sharp pH reduction. Growth of Clostridium beijerinckii and Paenibacillus spp. was detected in the swollen and non-swollen pouches after 7 weeks of storage at 7 °C, respectively. Both treatments resulted in a similar reduction in a* value, hue angle, and chlorophyll a and b. Both methods resulted in reductions in firmness, yet HPP caused less reduction compared to MAPS. Based on observed package swelling and changes in pH values, the shelf life of the treated green beans was determined to be 6 weeks for HPP and 12 weeks for MAPS, respectively, when stored at 2 °C or less, and 2 and 3 weeks, respectively, when stored at 7 °C.

In response to the increasing consumer demand for high-quality, minimally processed ready-to-eat (RTE) meals, the food industry has shown strong interests in exploring new processing technologies for production of safe RTE meals with an adequate shelf life in cold distribution chains. The purpose of this research was to understand the effect of high-pressure processing (HPP) and microwave-assisted thermal pasteurization on the quality attributes of green beans. The pasteurization conditions were selected as 600 MPa at 25 degrees C for 10 min for HPP and 70 degrees C for 2 min for processing with microwave-assisted pasteurization system (MAPS). Survival of L. innocua ATCC 51742 in green bean brine solution was analyzed right after the pasteurization processes. The quality attributes of the green beans, such as color, chlorophyll content, texture, vitamin C content, and pH, were further determined during storage at 2 degrees C for 36 days and 10 degrees C for 20 days. High-pressure treatment resulted in a 3.7-log CFU/g reduction in L. innocua ATCC 51742, whereas MAPS processing showed a 9.0-log CFU/g reduction. Both pasteurization processes provided significantly better green color retention when the beans were stored at 2 degrees C than when they were stored at 10 degrees C. Regardless of the pasteurization methods, the change in the greenness (a*) value of the beans followed similar trends during storage. Both methods caused an increase in the total color difference (Delta E) and a decrease in hue angle (yellowness) during storage (p < 0.05), but they had no significant effect on firmness, total chlorophyll content, and pH of the green beans. After the pasteurization processes, the vitamin C content of the HPP-treated green beans decreased significantly in comparison with the MAPS-treated beans (p < 0.05). This work reveals that both pasteurization treatments have a similar impact on quality attributes of green beans and that MAPS processing is more efficient in inactivating L. innocua ATCC 51742.

The food industry and the research community have shown interest in microwave pasteurization of packaged food products since the 1970s. Microwave heating offers possibilities of shorter processing time and better heating uniformity compared to conventional thermal processing using steam or hot water. It, thus, holds potential to deliver safe and higher quality foods. Factors that have hindered commercial applications of microwave pasteurization include engineering challenges in system design, relatively high costs for new equipment installation and operation, and un-familiarity with microwave heating systems. Consumer desire for convenience, food safety risks associated with e-commerce and home delivery of prepared meals, and regulatory requirements imposed by the Food Safety Modernization Act (FSMA) in the USA have generated great commercial interest in in-package pasteurization technologies. In this paper, we will review pathogens of concern in designing thermal pasteurization processes, regulatory guidelines for pasteurization, and advancements in microwave pasteurization system designs. We offer opinions as to how microwave assisted pasteurization will help the food deliver safe and high quality ready-to-eat meals to consumers through various distribution methods.