Nonthermal Food Processing Alternatives and Their Effects on Taste and Flavor Compounds of Beverages

Food drinks are normally processed to increase their shelf-life and facilitate distribution before consumption. Thermal pasteurization is quite efficient in preventing microbial spoilage of many types of beverages, but the applied heat may also cause undesirable biochemical and nutritious changes that may affect sensory attributes of the final product. Alternative methods of pasteurization that do not include direct heat have been investigated in order to obtain products safe for consumption, but with sensory attributes maintained as unchanged as possible. Food scientists interested in nonthermal food preservation technologies have claimed that such methods of preserving foods are equally efficient in microbial inactivation as compared with conventional thermal means of food processing. Researchers in the nonthermal food preservation area also affirm that alternative preservation technologies will not affect, as much as thermal processes, nutritional and sensory attributes of processed foods. This article reviews research in nonthermal food preservation, focusing on effects of processing of food drinks such as fruit juices and dairy products. Analytical techniques used to identify volatile flavor-aroma compounds will be reviewed and comparative effects for both thermal and nonthermal preservation technologies will be discussed.     

Trends in microbial control techniques for poultry products

Fresh poultry meat and poultry products are highly perishable foods and high potential sources of human infection due to the presence of several foodborne pathogens. Focusing on the microbial control of poultry products, the food industry generally implements numerous preventive measures based on the Hazard Analysis and Critical Control Points (HACCP) food safety management system certification together with technological steps, such as refrigeration coupled to modified atmosphere packaging that are able to control identified potential microbial hazards during food processing. However, in recent years, to meet the demand of consumers for minimally processed, high-quality, and additive-free foods, technologies are emerging associated with nonthermal microbial inactivation, such as high hydrostatic pressure, irradiation, and natural alternatives, such as biopreservation or the incorporation of natural preservatives in packaging materials. These technologies are discussed throughout this article, emphasizing their pros and cons regarding the control of poultry microbiota and their effects on poultry sensory properties. The discussion for each of the preservation techniques mentioned will be provided with as much detail as the data and studies provided in the literature for poultry meat and products allow. These new approaches, on their own, have proved to be effective against a wide range of microorganisms in poultry meat. However, since some of these emergent technologies still do not have full consumer's acceptability and, taking into consideration the hurdle technology concept for poultry processing, it is suggested that they will be used as combined treatments or, more frequently, in combination with modified atmosphere packaging.     

The inhibitory effect of plant essential oils on foodborne pathogenic bacteria in food

Abstract

In recent years, with the continuous improvement of people's living standard, the importance of healthy lifestyles is becoming more and more recognized. Therefore, food safety has attracted much attention. This has prompted people to study new technologies that can guarantee food safety without the use of preservatives. Compared with other types of food preservatives, essential oils (EOs) are gotten more attention, because they meet the current development trend of food additives about "green", "safety" and "health". Therefore, this paper focuses on the research of effective contribution of EOs to inhibit the growth of foodborne pathogens, systematically summarized the commonly used EOs and their main extraction methods and chemical components and, the antibacterial mechanism of EOs on food borne pathogens, systematically analysis the specific application case of EOs in food discussed. Hoping to provide some reference and help to the relevant researchers.     

The effects of sublethal doses of essential oils and their constituents on antimicrobial susceptibility and antibiotic resistance among food-related bacteria: A review

BackgroundEssential oils (EOs) and their individual constituents (ICs) have demonstrated strong and wide-spectrum antimicrobial activities against food-related bacteria. Frequently, the concentrations of EOs or ICs required to inhibit bacteria in foods are higher than those that are organoleptically acceptable, and their use at sublethal concentrations in combination with other preservation technologies has been proposed.Scope and approachBacteria have the capacity to develop physiological responses to sublethal growth conditions, which can lead to decreased susceptibility toward the same or other stressing agents, including resistance to antibiotics. Despite this knowledge, studies regarding the efficacy of EOs and ICs have mostly focused on doses that inactivate target bacteria in laboratorial media or in real foods, while less is known about the implications of their use at sublethal concentrations on bacterial susceptibility to antimicrobials, physical processes and antibiotic resistance. This review presents the available studies focused on the effects of the exposure of food-related bacteria to EOs or ICs at sublethal concentrations on alterations in susceptibility to homologous or heterologous stressing agents, including antibiotic-resistance, and related physiological responses in bacteria experiencing these stresses.Key findings and conclusionsThe findings of the available studies show that changes in susceptibility to antimicrobials and physical procedures as well as in antibiotic resistance vary with the target bacterium and the applied stress condition. Moreover, the observed stress-induced physiological responses have been varied. Notably, for the majority of the studies, the exposure of food-related bacteria to these stresses has not resulted in relevant changes in the sensitivity of the bacteria to antimicrobials, physical processes or antibiotics, which indicate that changes in bacterial sensitivity are not a major problem when considering the use of EOs or ICs in food preservation.     

Effects of Ultraviolet Light and High‐Pressure Processing on Quality and Health‐Related Constituents of Fresh Juice Products

Fresh juices are highly popular beverages in the global food market. They are perceived as wholesome, nutritious, all‐day beverages. For a fast growing category of premium juice products such as cold‐pressed juices, minimal‐processing nonthermal techniques such as ultraviolet (UV) light and high‐pressure processing (HPP) are expected to be used to extend shelf‐life while retaining physicochemical, nutritional, and sensory characteristics with reduced microbial loads. Also, UV light and HPP are approved by regulatory agencies and recognized as one of the simplest and very environmentally friendly ways to destroy pathogenic organisms. One of the limitations to their more extensive commercial application lies in the lack of comparative effects on nutritional and quality‐related compounds in juice products. This review provides a comparative analysis using 92 studies (UV light: 42, HPP: 50) mostly published between 2004 and 2015 to evaluate the effects of reported UV light and HPP processing conditions on the residual content or activity of bioactive compounds such as vitamins, polyphenols, antioxidants, and oxidative enzymes in 45 different fresh fruit and vegetable juices (low‐acid, acid, and high‐acid categories). Also, the effects of UV light and HPP on color and sensory characteristics of juices are summarized and discussed.     

Principles and recent applications of novel non-thermal processing technologies for the fish industry—a review

Thermal treatment is a traditional method for food processing, which can kill microorganisms but also lead to physicochemical and sensory quality damage, especially to temperature-sensitive foods. Nowadays consumers’ increasing interest in microbial safety products with premium appearance, flavor, great nutritional value and extended shelf-life has promoted the development of emerging non-thermal food processing technologies as alternative or substitution to traditional thermal methods. Fish is an important and world-favored food but has a short shelf-life due to its extremely perishable characteristic, and the microbial spoilage and oxidative process happen rapidly just from the moment of capture, making it dependent heavily on post-harvest preservation. The applications of novel non-thermal food processing technologies, including high pressure processing (HPP), ultrasound (US), pulsed electric fields (PEF), pulsed light (PL), cold plasma (CP) and ozone can extend the shelf-life by microbial inactivation and also keep good sensory quality attributes of fish, which is of high interest for the fish industry. This review presents the principles, developments of emerging non-thermal food processing technologies, and also their applications in fish industry, with the main focus on microbial inactivation and sensory quality. The promising results showed great potential to keep microbial safety while maintaining organoleptic attributes of fish products. What’s more, the strengths and weaknesses of these technologies are also discussed. The combination of different food processing technologies or with advanced packaging methods can improve antimicrobial efficacy while not significantly affect other quality properties under optimized treatment.     

Nonthermal Technologies for Fruit and Vegetable Juices and Beverages: Overview and Advances

In recent years, there has been a growing interest in the design of novel nonthermal processing systems that minimally modify sensory, nutritional, and functional properties of fruit and vegetable juices and beverages. The benefits of nonthermal treatments are strongly dependent on the food matrix. Thus, an understanding of the effects that these technologies exert on the properties of juices and beverages is important to design and optimize technological parameters to produce value‐added products. This review covers research on nonthermal electrical treatments, high pressure processing, ultrasound, radiation processing, inert gas treatments, cold plasma, and membrane processing. Advances towards optimization of processing conditions, and combined technologies approaches have been also extensively reviewed. This information could be useful to: (1) manage processing systems and optimize resources; (2) preserve nutritional value and organoleptic properties, and (3) provide processing conditions for validation of these technologies at the industrial scale.     

Control of Pathogenic and Spoilage Microorganisms in Fresh‐cut Fruits and Fruit Juices by Traditional and Alternative Natural Antimicrobials

ABSTRACT: Traditional antimicrobials have been extensively used for many years. However, consumers are currently demanding wholesome, fresh‐like, and safe foods without addition of chemically synthesized preservatives. The application of novel natural antimicrobials to assure safety of fresh‐cut fruits and unpasteurized juices while preventing quality loss is a promising alternative. The effectiveness of these natural substances added to fruit derivatives has been studied by different researchers. Antimicrobials of animal (lactoperoxidase, lysozyme, and chitosan), plant (essential oils, aldehydes, esters, herbs, and spices), and microbial origin (nisin) can be used to effectively reduce pathogenic and spoilage microorganisms in fresh‐cut fruits and fruit juices. Nevertheless, the use of these compounds at a commercial level is still limited due to several factors such as impact on sensory attributes or, in some cases, regulatory issues concerning their use. Therefore, extensive research on the effects of each antimicrobial on food sensory characteristics is still needed so that antimicrobial substances of natural origin can be regarded as feasible alternatives to synthetic ones.     

Nonthermal preservation of foods using combined processing techniques

In the last 2 decades, consumer demand for fresher, higher quality, and safer food has promoted research on nonthermal methods of food preservation for the inactivation of microorganisms and enzymes as an alternative to thermal processes. However, the high resistance of certain enzymes and microorganisms to nonthermal processes, especially bacterial spores, limit their application. To expand the use of nonthermal processes in the food industry, combinations of these technologies with traditional or emerging food preservation techniques are being studied. The use of nonthermal processes in combination with other preservation technologies presents a number of potential benefits to food preservation. The purpose of this article is to review some successful combinations of different nonthermal technologies, such as high hydrostatic pressure, ultrasound, pulsed electric fields, and irradiation, with traditional or emerging food preservation technologies.     

Combining nonthermal technologies to control foodborne microorganisms

Novel nonthermal processes, such as high hydrostatic pressure (HHP), pulsed electric fields (PEFs), ionizing radiation and ultrasonication, are able to inactivate microorganisms at ambient or sublethal temperatures. Many of these processes require very high treatment intensities, however, to achieve adequate microbial destruction in low-acid foods. Combining nonthermal processes with conventional preservation methods enhances their antimicrobial effect so that lower process intensities can be used. Combining two or more nonthermal processes can also enhance microbial inactivation and allow the use of lower individual treatment intensities. For conventional preservation treatments, optimal microbial control is achieved through the hurdle concept, with synergistic effects resulting from different components of the microbial cell being targeted simultaneously. The mechanisms of inactivation by nonthermal processes are still unclear; thus, the bases of synergistic combinations remain speculative. This paper reviews literature on the antimicrobial efficiencies of nonthermal processes combined with conventional and novel nonthermal technologies. Where possible, the proposed mechanisms of synergy is mentioned.     

Nonthermal physical technologies to decontaminate and extend the shelf-life of fruits and vegetables: Trends aiming at quality and safety

Minimally processed fruits and vegetables are one of the major growing sectors in food industry. This growing demand for healthy and convenient foods with fresh-like properties is accompanied by concerns surrounding efficacy of the available sanitizing methods to appropriately deal with food-borne diseases. In fact, chemical sanitizers do not provide an efficient microbial reduction, besides being perceived negatively by the consumers, dangerous for human health, and harmful to the environment, and the conventional thermal treatments may negatively affect physical, nutritional, or bioactive properties of these perishable foods. For these reasons, the industry is investigating alternative nonthermal physical technologies, namely innovative packaging systems, ionizing and ultraviolet radiation, pulsed light, high-power ultrasound, cold plasma, high hydrostatic pressure, and dense phase carbon dioxide, as well as possible combinations between them or with other preservation factors (hurdles). This review discusses the potential of these novel or emerging technologies for decontamination and shelf-life extension of fresh and minimally processed fruits and vegetables. Advantages, limitations, and challenges related to its use in this sector are also highlighted.     

非热杀菌技术在即食肉制品中的应用研究进展

即食肉制品在生产和消费环节极易受到微生物污染,严重影响其品质和安全。传统热杀菌技术虽然能有效灭活微生物,但会对即食肉制品的营养和感官品质产生不良影响。近年来,非热杀菌技术逐渐受到关注,该技术处理温度低,对食品的风味、色泽和营养成分影响较小,避免了传统热杀菌技术造成的食品品质劣变问题。目前,在即食肉制品中应用较为广泛的非热杀菌技术主要有超高压、辐照、紫外照射、脉冲光照射和冷等离子体。本文综述上述5 种非热杀菌技术对即食肉制品的杀菌作用及对其品质的影响,以期为非热杀菌技术在即食肉制品加工中的应用提供参考。     

Edible alginate-based coating as carrier of antimicrobials to improve shelf-life and safety of fresh-cut melon

The effect of malic acid and essential oils (EOs) of cinnamon, palmarosa and lemongrass and their main active compounds as natural antimicrobial substances incorporated into an alginate-based edible coating on the shelf-life and safety of fresh-cut "Piel de Sapo" melon (Cucumis melo L.) was investigated. Melon pieces (50 g) were coated with alginate-based edible coating containing malic acid (EC) and EOs or their active compounds before to be packed in air filled polypropylene trays and stored at 5 degrees C for shelf-life and sensory studies. On the other hand, melon pieces were inoculated with a Salmonella Enteritidis (10(8) CFU/ml) culture before applying the coatings containing malic acid and EOs or their active compounds to safety study. Controls of fresh-cut melon non-coated or coated with EC without EOs were also prepared. EC was effective to improve shelf-life of fresh-cut melon from microbiological (up to 9.6 days) and physicochemical (>14 days) points of view in comparison with non-coated fresh-cut melon, where microbiological and physicochemical shelf-life was up to 3.6 days and lower than 14 days, respectively. In addition, the incorporation of EOs or their active compounds into the edible coating prolonged the microbiological shelf-life by more than 21 days in some cases due probably to an enhanced antimicrobial effect of malic acid+EOs; however, some fresh-cut melon characteristics were affected such as firmness and color causing a reduction of physicochemical shelf-life. Significant reductions (p<0.05) of S. Enteritidis population in inoculated coated fresh-cut melon were achieved, varying the effectiveness of the coatings depending on the EOs or the active compound and their concentrations. According to the results, palmarosa oil incorporated at 0.3% into the coating appear to be a promising preservation alternative for fresh-cut melon, since it had a good acceptation by panellists, maintained the fruit quality parameters, inhibited the native flora growth and reduced S. Enteritidis population.     

Antimicrobial activity of essential oils on Salmonella enteritidis, Escherichia coli, and Listeria innocua in fruit juices

The antimicrobial properties of essential oils (EOs) and their derivatives have been known for years. However, the information published about the minimal effective concentration of EOs against microorganisms in fruit juices is scarce. In this study, both MIC and MBC of six EOs (lemongrass, cinnamon, geraniol, palmarosa, or benzaldehyde) against Salmonella Enteritidis, Escherichia coli, and Listeria innocua were determined by the agar and broth dilution methods, respectively. All of the six EOs inhibited the microbial (Salmonella Enteritidis, E. coli, and L. innocua) growth at a concentration from 1 microl/ ml (MIC). These studies led to choosing the three most effective EOs. Lemongrass, cinnamon, and geraniol were found to be most effective in inhibiting the growth of the microorganisms and thus were used for the MBC analysis. On this last point, significant differences (P < 0.05) among EOs, their concentrations, and culture media (apple, pear, and melon juices, or tryptone soy broth medium) were found after comparing the results on MBC for each microorganism. A concentration of 2 microl/ml from lemongrass, cinnamon, or geraniol was enough to inactivate Salmonella Enteritidis, E. coli, and L. innocua in apple and pear juices. However, in melon juice and tryptone soy broth medium, concentrations of 8 and 10 microl/ml from cinnamon, respectively, or 6 microl/ml from geraniol were necessary to eliminate the three microorganisms, whereas lemongrass required only 5 micro/ml to inactivate them. These results suggest that EOs represent a good alternative to eliminate microorganisms that can be a hazard for the consumer in unpasteurized fruit juices. The present study contributes to the knowledge of MBC of EOs against pathogenic bacteria on fruit juices.     

Protein Oxidation in Processed Meat: Mechanisms and Potential Implications on Human Health

Processed meats represent a large percentage of muscle foods consumed in the western world. Various processing steps affect the physicochemical properties of the meat, compromise its nutritional components, or produce some compounds that are of health concern. Hence, the impact of oxidation on human health and the aging process and the influence of diet on these harmful reactions are of growing interest. Past decades have seen more focus on lipid oxidation, microbial deterioration, and pathogenicity, as well as production of carcinogenic compounds during meat processing. The oxidation of protein, which is a major component in meat systems, has received less attention. Protein oxidation has been defined as a covalent modification of protein induced either directly by reactive species or indirectly by reaction with secondary by‐products of oxidative stress. Not only are these modifications critical for technological and sensory properties of muscle foods, they may have implications on human health and safety when consumed. Cooking, for example, has been observed to increase free radical generation while it also decreases the antioxidant protection systems in meat, both of which contribute to protein oxidation. Many other meat processing techniques, as well as other emerging technologies, may significantly affect protein oxidation and protein overall quality. This paper explores the current understanding of meat processing techniques and their possible effects on the status of protein oxidation and nutritional value, as well as their possible implications on human health.     

Biological Aspects in Food Preservation by Ultraviolet Light: a Review

The potential to commercialize nonthermal ultraviolet (UV) light technologies as new methods for preserving food products has caught the attention of a food industry that wishes to fulfill consumers' demands for fresh products. Numerous investigations have demonstrated UV light's ability to inactivate a wide range of microorganisms. However, the lack of UV sensitivity data from pathogenic and spoilage bacteria is evident. In addition, the main factors associated with UV light in terms of microbial lethality remain unclear. This review surveys critical factors (process, microbial, and environmental parameters) that determine UV microbial resistance and assess the effects of such factors on the inactivation mechanism and repair pathway efficiency. The effects of some of these factors, such as prior sublethal stresses and post-recovery conditions of UV treatments, may extensively improve the damage repair capacity and thus microbial survivability. Further research is needed to establish adequate control measures pre- and post-UV treatments. Furthermore, the possibility of combining UV light with conventional preservatives and other nonthermal technologies was assessed. The combination of UV light with mild heating or oxidant compounds could offer promising treatments to enhance the safety and stability of minimally processed foods.     

Alternatives to conventional thermal treatments in fruit-juice processing. Part 2: Effect on composition,phytochemical content,and physicochemical,rheological, and organoleptic properties of fruit juices

Traditional thermal techniques may cause losses in nutritional quality and phytochemical contents, and also in physicochemical, rheological, and organoleptic properties of processed fruit juices. This paper provides an overview of the effect on these qualities by the use of alternatives to traditional thermal treatments in fruit-juice processing, for three key operations in fruit-juice production such as microbial inactivation, enzyme inactivation, and juice-yield improvement. These alternatives are UV light, high-intensity light pulses, γ-irradiation, pulsed electric fields, radiofrequency electric fields, Ohmic heating, microwave heating, ultrasound, high hydrostatic pressure, supercritical carbon dioxide, ozonation, and flash-vacuum expansion. Although alternatives to heat treatments seem to be less detrimental than the thermal treatment, there are many parameters and conditions that influence the output, as well as the nature of the juice itself, hampering comparisons between different studies. Additionally, future research should focus on understanding the mechanisms underlying the changes in the overall quality of fruit juices, and also on scaled-up processes, process design, and optimization that need to be deal with in detail to maximize their potential as alternative nonthermal technologies in fruit-juice processing while maintaining fruit-juice attributes to the maximum.     

浆果果汁真伪鉴别技术研究进展

以蓝莓、树莓为代表的浆果类水果素有“黄金水果”的美誉,由于产量低、保质期短和价格高昂,浆果果汁掺假、造假、错误标签等导致的食品质量和安全争议不断发生,果汁真伪鉴别技术面临巨大挑战。目前,常用的浆果真伪检测方法主要是常规理化法和传统的分子生物学方法,这些方法在浆果果汁鉴定上各有优缺点。如理化方法的优势在于浆果的质量控制和品质评价,对产品中植源性成分的识别易受个体生长发育、加工条件等外部因素的影响;而基于DNA的分子生物学方法更多的用于果汁中植源性成分的识别。面对浆果果汁掺假造假现象,本文综述了近年来常用于浆果及其果汁质量控制和真伪鉴别技术的研究进展,主要包括感官技术、理化技术和分子生物学技术。     

Nonthermal Processes for Shelf‐Life Extension of Seafoods: A Revisit

For the past two decades, consumer demand for minimally processed seafoods with good sensory acceptability and nutritive properties has been increasing. Nonthermal food processing and preservation technologies have drawn the attention of food scientists and manufacturers because nutritional and sensory properties of such treated foods are minimally affected. More importantly, shelf‐life is extended as nonthermal treatments are capable of inhibiting or killing both spoilage and pathogenic organisms. They are also considered to be more energy‐efficient and to yield better quality when compared with conventional thermal processes. This review provides insight into the nonthermal processing technologies currently used for shelf‐life extension of seafoods. Both pretreatments such as acidic electrolyte water and ozonification and processing technologies, including high hydrostatic pressurization, ionizing radiation, cold plasma, ultraviolet light, and pulsed electric fields, as well as packaging technology, particularly modified atmosphere packaging, have been implemented to lower the microbial load in seafood. Thus, those technologies may be the ideal approach for the seafood industry, in which prime quality is maintained and safety is assured for consumers.