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Highlights • Photobacteria exploit horizontal gene transfer for niche adaptation. • P. phosphoreum divides into two subspecies with no correlation to isolation origin or metabolism. • P. phosphoreum has wider tools for stress response and antimicrobial activity. • P. iliopiscarium divides in two clades (marine/terrestrial) with distinct environmental adaptation. • P. carnosum forms by one single clade with wide sugar utilization., Photobacterium (P.) is a genus widely studied in regards to its association with and ubiquitous presence in marine environments. However, certain species (P. phosphoreum, P. carnosum, P. iliopiscarium) have been recently described to colonize and spoil raw meats without a marine link. We have studied 27 strains from meat as well as 26 strains from marine environments in order to probe for intraspecies marine/terrestrial subpopulations and identify distinct genomic features acquired by environmental adaptation. We have conducted phylogenetic analysis (MLSA, ANI, fur, codon usage), search of plasmids (plasmidSPADES), phages (PHASTER), CRISPR-cas operons (CRISPR-finder) and secondary metabolites gene clusters (antiSMASH, BAGEL), in addition to a targeted gene search for specific pathways (e.g. TCA cycle, pentose phosphate, respiratory chain) and elements relevant for growth, adaptation and competition (substrate utilization, motility, bioluminescence, sodium and iron transport). P. carnosum appears as a conserved single clade, with one isolate from MAP fish clustering apart that doesn't, however, show distinct features that could indicate different adaptation. The species harbors genes for a wide carbon source utilization (glycogen/starch, maltose, pullulan, fucose) for colonization of diverse niches in its genome. P. phosphoreum is represented by two different clades on the phylogenetic analyses not correlating to their origin or distribution of other features analyzed that can be divided into two novel subspecies based on genome-wide values. A more diverse antimicrobial activity (sactipeptides, microcins), production of secondary metabolites (siderophores and arylpolyenes), stress response and adaptation (bioluminescence, sodium transporters, catalase, high affinity for oxygen cytochrome cbb3 oxidase, DMSO reductase and proton translocating NADH dehydrogenase) is predicted compared to the other species. P. iliopiscarium was divided into two clades based on source of isolation correlating with phylogeny and distribution of several traits. The species shows traits common to the other two species, similar carbon utilization/transport gene conservation as P. carnosum for the meat-isolated strains, and predicted utilization of marine-common DMSO and flagellar cluster for the sea-isolated strains. Results additionally suggest that photobacteria are highly prone to horizontal acquisition/loss of genetic material and genetic transduction, and that it might be a strategy for increasing the frequency of strain- or species-specific features that offers a growth/competition advantage., Graphical abstract Image, graphical abstract

Pseudomonas fragi is the predominant bacterial species associated with spoiled aerobically stored chilled meat worldwide. It readily forms biofilms on meat under refrigerated temperature conditions used in the meat industry. Biofilm growth leads to slime development on meat which in turn becomes a major quality defect. To understand the genetic regulation that aids P. fragi to survive under chilled conditions used in the meat industry, as well to obtain an overview of the transcriptomic behavior of this organism when grown as biofilms, RNA sequencing was carried out for the main stages of the P. fragi 1793 biofilm. RNA was extracted at different stages of the biofilm cycle namely initiation, maturation and dispersal. At the same time, the biofilm growth was assessed by fluorescent staining and imaging using confocal laser scanning microscope. The results of RNA sequencing were verified by qRT-PCR using twelve genes that were most significantly up and down regulated at each stage. Differential expression analysis at biofilm maturation revealed 332 significantly upregulated genes and 37 downregulated genes relative to initiation. Differential expression analysis at biofilm dispersal reveled 658 upregulated and 275 downregulated genes relative to initiation. During biofilm maturation and dispersal, genes coding for flp family type IVb pilin, ribosome modulation factor, creatininase were the most upregulated genes while genes encoding for iron uptake systems including TonB-dependent siderophore receptor and taurine transport were significantly down regulated. The results show that protein synthesis and cellular multiplication cease after the biofilm population maximum has reached.

Despite significant advancements in food science and technology, food-borne illnesses remain a major challenge worldwide. Although the food industry traditionally relies on good manufacturing practices and implementation of hazard analysis critical control points for reducing food contamination during manufacture, preventing food contamination and spoilage during postprocessing storage or transport remains a technological challenge requiring further research. Nearly 30%–50% (~1.2–2 billion tones) of all food produced globally is wasted due to inadequate storage or poor transportation practices. As more and more consumers demand a safe and minimally processed product with enhanced shelf life, edible coatings incorporated with natural antimicrobials represent a safe, effective, and environmentally friendly technology to achieve this goal. Antimicrobial edible coating matrices based on complex polysaccharides, proteins, lipids, or their derivatives have been successfully developed. This chapter will discuss the development, effectiveness, and advantages of antibacterial edible coatings formulated with an array of natural antimicrobials for controlling bacterial contamination and spoilage of meat products, fresh fruits, and vegetables. In addition, the antibacterial mechanism of various ingredients and their effect on the biochemical and physical properties of coating matrix will be discussed.

The concept of meat deterioration and detection is always an area of interest for the food technologists, food quality control agencies, and the meat industry. Meat is not only nutritious to consumers, but is also an excellent source of nutrients for microbial growth. Muscle foods are described as spoiled if organoleptic changes make them unacceptable to the consumer. These organoleptic characteristics can include changes in appearance, the development of odors, and slime formation. Meat spoilage is the result of decomposition and the formation of metabolites by the growth of microorganisms. The organoleptic changes vary according to the species of microflora, the characteristics of the meat, and processing methods. The microbial spoilage detection thus is very important and direct and indirect methods of detection of spoilage bacteria are widely studied. Enumeration methods using ATP bioluminescence and fluorescent techniques are already in use and are popular due to quick results. Molecular methods to detect a group of spoilage bacteria using techniques like multiplex polymerase chain reaction have already been tried. Detection of spoilage by screening for microbial metabolites is the common approach and identifying specific bacteria is not necessary. The concept of an electronic nose using odor sensors, for example, conducting organic polymers and metal oxide conductors, is promising for spoilage detection. The modified versions of spectroscopy are widely studied in the field of meat deterioration detection. Fourier transform infrared spectroscopy, electrical impedance spectroscopy, and near-infrared spectroscopy are some of those methods. The use of lasers especially laser speckle imaging has been already put into use in this field. The latest technology introduced in the field of meat spoilage detection is the use of smartphones with different attachments. These attachments make the smartphones perform the duties of high-end equipment such as biosensors, fluorescence readers, calorimeters, etc., which can be used to detect spoilage.

Amine-responsive bilayer films were developed by using agar (AG), anthocyanins (AN), gellan gum (GG) and TiO 2 nanoparticles for visual monitoring of meat spoilage. The AG-AN layer worked as the sensing layer to volatile amines, while GG-TiO 2 layer served as the light barrier layer and simultaneously the conducting layer to improve the illumination stability and electrochemical writing ability of the AG-AN layer, respectively. The Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) spectra indicated the successful fabrication of bilayer films. Illumination experiments showed that the incorporation of TiO 2 in the GG-TiO 2 layer significantly improved the illumination stability of AN in the AG-AN layer. Meanwhile, electrochemical writing process could be easily conducted on the AG-AN layer in the presence of GG-TiO 2 layer, indicating the feasibility of ink-free printing on bilayer biopolymer films. The AG-AN/GG-2%TiO 2 film presented a limit of detection of 0.018 mM to trimethylamine (TMA), a typical basic gas generated during meat spoilage. Based on its good illumination stability and sensing ability to basic gases, the AG-AN/GG-2%TiO 2 film exhibited rose red-to-green color changes along with the spoilage of pork and silver carp, indicating its great potential for monitoring meat spoilage in intelligent food packaging.

Globally one-third of foods produced for human consumption is wasted each year. This wastage is primarily due to spoilage that deems food unacceptable for consumers. Among the various food products, meat is one of the most perishable commodities due to its moderate pH and high nutrient and moisture content. The primary factors that contribute to meat spoilage include microbial growth, lipid oxidation, and enzymatic autolysis. The nutrient breakdown in meat by microbial growth and autolysis results in the development of off-odors and flavors, slime formation, and discoloration, thereby making it unacceptable for human consumption. This chapter provides an overview of microbial spoilage of meat, spoilage microbiome, mechanisms and factors contributing to microbial spoilage, its effect on meat quality, and methods to detect microbial spoilage in meat.

This chapter will introduce the reader to an alternative heat-processing technology (i.e., ohmic heating) and will explore the potential for this technology in the pasteurization of meat and meat products. The chapter begins with an overview of conventional thermal processing and the calculation of pasteurization units and cook values from time–temperature profiles. It then goes on to introduce the basic principles of ohmic heating including fundamentals of electrical circuitry and the mechanism of ohmic heating. The main factors influencing heat generation rate are then considered, including electrical field strength, electrical conductivity with reference to the impact of meat product formulation, and size reduction on conductivity. Microbial reduction and product quality in ohmically heated meat products are then considered. Although electrical fields when applied to foods in other forms (e.g., high voltage pulsed electrical fields) have been shown to inactivate microorganisms by nonthermal means (i.e., electroporation), it is largely believed that microbial inactivation under ohmic heating occurs predominantly by thermal means. The volumetric nature of ohmic heating means products can be elevated to target temperatures in considerably shorter time than by conventional heating, which opens the real possibility of continuous cooking of meat products. In terms of quality assessments, cook loss/yield of meat products in ohmically cooked products is generally superior to conventionally cooked in noncomminuted meats and comparable to conventional in highly comminuted products. From a textural perspective, ohmic and conventionally cooked products are generally comparable. However, in larger diameter products greater uniformity in the surface versus center texture and surface versus center color has been reported in ohmically cooked products compared to products cooked conventionally. This can largely be attributed to the volumetric nature of ohmic heating which avoids over heating surfaces while waiting for the cold spot in the geometric center to reach target temperatures. From an economic perspective, ohmic heating offers considerably improved energy consumption, higher cooking yields, and increased product throughput. Overall it would appear that ohmic heating has considerable potential as a technology for the pasteurization of meat and meat products, whereas commercial systems need to be developed, and industry awareness needs to be increased if ohmic heating is to achieve its true potential in this sector.

In this chapter several aspects of fruit juice microbiology are addressed, with an overview of spoilage microorganisms and pathogens. Data on the different fruit juices, sources of contamination, spoilage caused by microorganisms, outbreaks involving foodborne pathogens, and mycotoxins produced in fruit juice are provided. Additionally, the international guidelines required for fruit juice safety are discussed.

Raw meat is one of the most shelf-unstable food materials due to its abundance in nutrients ideally suited for microorganisms. Because most spoilage bacteria are mesophilic, temperature control to below or above their optimum growth condition is essential to meat quality protection. While low-temperature preservation (refrigeration and freezing) is effective to retard microbial growth and proliferation, heat treatments (pasteurization and sterilization) have also been used to inactivate both pathogenic and spoilage microbes. Apart from delayed microbial growth, biochemical and chemical reactions occur during postmortem storage of fresh meat, and several endogenous proteolytic enzymes are involved in the aging-induced changes in meat tenderness and flavor. Unwanted textural changes also occur in frozen meat. Of the various available preservation techniques for fresh and cooked meat, temperature control remains the most effective and “green” method, or a main component in “hurdle technology,” to achieve the purpose.

Meat and meat products and fish and fish products represent excellent growth media for a large variety of spoilage microorganisms, originating from breeding, fishing, harvesting, preslaughter husbandry practices, and handling during slaughtering, processing, and selling. This microbial population includes psychrotolerant and/or psychrotrophic Gram-negative and Gram-positive bacteria, molds, and yeasts, whose metabolic activity may lead to the production of ammonia, biogenic amines, nonproteic nitrogen compounds, alcohols, ketones, aldehydes, esters, gas (CO2), and other molecules, being responsible of off-odors, off-flavors, discoloration, slime, and swelling of the packages. The storage temperature and the processing technologies may limit or slow down the microbial growth and improve meat and fish shelf life.

Milk’s combination of water, fats, proteins, and vitamins allows for the growth of a variety of bacteria, especially psychrotrophic bacteria that are able to grow under cold conditions. Raw milk, pasteurized milk, cheese, and other dairy products support different and diverse groups of microorganisms which can cause product spoilage. Light can also contribute to the spoiling of dairy products. There are many techniques, however, such as pasteurization and special packaging, which are used to protect these dairy products from the adverse effects of microbial overgrowth and light. Farmers, dairy processors, and consumers use many methods to measure the degree of spoilage and gage milk quality. Preventing microbial growth and extending shelf life not only can alleviate costs for producers, retailers, and consumers, but also can limit the environmental impact of dairy product production and consumption.

The spoilage of foods by microorganisms presents a significant loss of the food supply in both developed and developing countries. The nature of the loss is different. In developed countries the loss occurs from the retailer to the consumer and with the consumers themselves. In developing countries food is spoiled because of a lack of infrastructure. A variety of intrinsic and extrinsic factors influence the growth of microorganisms in foods and their subsequent spoilage. New food processing methods hold promise for increasing shelf life of food products and reducing spoilage.

Black pepper (Piper nigrum L.) is one of the most widely used spices, and the constituent parts of its essential oil contribute to its value. Although traditionally used as a culinary ingredient, fragrant aromatic, and medicine, it is presently used in the food, cosmetic, and pharmaceutical industries. The recognition of the antioxidant and antimicrobial properties of the essential oil of black pepper fostered research and proposals for its potential use as a natural food preservative. This is because existing methods of food preservation involving the use of synthetic preservatives have been reported to have undesirable effects on health and sometimes do not completely eliminate microorganisms. Essential oil of black pepper has been used to preserve orange juice and pork. Also its effect on meat spoilage organisms has been extensively studied, prompting the call for further studies and its subsequent adoption as a natural preservative.

Monitoring of meat and fish spoilage by electronic tongues (e-tongue) is a particular application that has been developed at a later stage in comparison with the analysis of other types of foods of liquids. The reason for this delay has been the difficulty of finding measuring methods able to achieve a good contact between the electrodes of the tongue and the samples in order to obtain a good reproducibility of the results. In this chapter we report an overview of work devoted to the use of potentiometric, voltammetric, or impedance spectroscopy electronic tongues in the monitorization of fish or meat spoilage.

Yeast spoilage is when growth of undesirable yeasts occurs on or in foods and beverages. Implications of food spoilage, along with the known factors that can contribute to yeast growth, are considered. Biochemistry of spoilage is discussed, with examples of three common spoilage yeasts.

It is important that canned foods be commercially sterile, i.e. the condition achieved by the application of heat, which renders the food free from any viable micro-organisms (including spores) of public health significance and any micro-organisms capable of reproducing in the food under ambient (i.e. normal nonrefrigerated) conditions of storage and distribution. The safety of the product is nonnegotiable, but the quality of the product is important, because if there is any microbiological or chemical spoilage activity the product will not be acceptable to consumers. This chapter covers the various kinds of spoilage that can occur.

High-pressure processing (HPP) is a non-thermal mild technology of particular interest to the meat sector since it guarantees microbiological safety and extends product shelf-life without modifying nutritional and sensory characteristics. This chapter reviews published information on the effect of HPP on the volatiles of pork meat products. Pressurization does not markedly modify the volatile profile of pork meat products immediately after treatment, but the volatile profiles of treated and untreated products during storage usually differ. The effect of HPP greatly depends on the treatment conditions, particularly pressure level, and on the type of meat product. Sampling techniques for the analysis of volatile compounds in meat products are also discussed.

This article is a revision of the previous edition article by D.R. Twiddy, P. Wareing, volume 3, pp 2045–2050, © 1999, Elsevier Ltd.

Deleterious changes of a chemical or microbial nature in meat lead to consumers’ rejection of the product. Due to the diversity of chemicals in meats, a wide variety of microorganisms can be present. Raw meat shelf-life extension is generally achieved by either freezing or chilling, while processed meats are subjected to various fabrication processes. In both cases, the aim is inhibition of microbial growth to various degrees. The native initial microflora, the meat substrate, the alterations during processing, the added ingredients, and the storage temperature, time, and gas atmosphere, among other factors, define the rate and extent of spoilage.

Food canning and heat treatment is currently the most important application in the world for the commercial preservation of food. It involves dispensing the food in a container that is hermetically sealed to be impermeable to liquids, gases, and microorganisms before being subject to sufficient heat to inactivate toxins, enzymes, and undesirable microorganisms.

This article is a revision of the previous edition article by Karen M.J. Hansen, Derrick A. Bautista, volume 3, pp 2051–2056, © 1999, Elsevier Ltd.

This article is focused on bacterial spoilage of certain representative fresh food commodity groups and how spoilage progresses for each commodity group. The intrinsic and extrinsic characteristics that most prominently contribute to microbiological spoilage of each commodity are considered. Interactions between pathogenic and spoilage bacteria that affect the quality and safety of each commodity group are discussed. In addition, the role that bacterial pathogens play as spoilage organisms is addressed. Commodity groups included in this article are meat and poultry, seafood, raw and pasteurized milk, and minimally processed vegetables.

This article is a revision of the previous edition article by Maurice O. Moss, volume 3, pp 2056–2062, © 1999, Elsevier Ltd.

Yeasts and molds are important microorganisms related to human welfare, safety, and food resources. They contribute greatly to the food industry in areas such as winemaking, single-cell protein production, brewing, baking, vitamin production, etc. However, under certain conditions they can act as potential spoilage organisms in food, especially in processed, preserved, and refrigerated food. Enumeration and identification of yeasts and molds from foods are of great importance in understanding the value of these organisms in various food systems as well as their role in spoilage. Knowledge of how certain yeasts and molds colonize meat products and of their effects on the meat products is essential in order to prevent economic losses during spoilage or to maximize desirable fermentation of certain cured meat products by yeasts and molds. Occasionally, some pathogenic yeasts and molds might occur in meat and meat products that may pose food safety issues.

A seafood product is considered spoiled when it is deemed by consumers to be unacceptable for consumption due to poor appearance, flavor, or texture. Microbial spoilage occurs when the formation of off-flavors, off-odors, discoloration, or slime reach objectionable levels, the determination of which is influenced by cultural and economic background. Spoilage of seafood depends on the types and populations of microbial contaminants, intrinsic factors (pH, water activity, enzyme activity, and nutrient content), and extrinsic environmental factors (temperature, package head space gas composition, and storage time). Although spoiled seafoods generally are not unsafe, spoiled fish of the Scombridae family can result in the formation of toxic biogenic amines such as histamine.

Meats are spoiled by microorganisms on or in them when the microorganisms cause changes that consumers regard as undesirable or offensive. Undesirable changes include discoloration, off-odors, off-flavors, slime, and visible microbial colonies. The spoilage conditions that develop depend on intrinsic qualities of the fresh or processed meat, such as the substrates provided for bacterial growth and the pH and water activity of the meat; and extrinsic factors such as the atmosphere around the meat and the storage temperature. The article discusses how these various qualities and factors affect the compositions of spoilage flora and the spoilage activities of their component organisms.

Milk and dairy products are important components of the diet worldwide. The quality and shelf life of liquid milk as well as dairy products are often compromised by flavor, odors, and visual defects arising from the bacterial growth and activities of heat-stable enzymes produced by psychrotrophic bacteria before processing. This article focuses on the liquid milk spoilage characteristics, as well as the flora and enzymatic activities involved, and reviews some methods allowing for the detection or prediction of milk spoilage.

Meat and meat products are potential vehicles of hazards to human health. Types of hazards that may be present in meat products include chemicals (causing acute or long-term toxicity) and biological agents (pathogenic bacteria, viruses, parasites, and abnormal prions causing transmissible spongiform encephalopathies), as well as physical objects (may cause injury). Biological hazards are of most concern. Their occurrence in meat and meat products is unavoidable because contaminants are present in and on the animals and in their environment. Raw meat and not fully heated (canned) or fermented/dried meat products are highly perishable, which makes them prone to quick spoilage and of compromised safety due to microbial presence and growth. The quality and safety of meat and meat products are best maintained by an integrated preventive approach throughout all segments of the meat sector, including producers, processors, distributors, retailers, food service, as well as consumers. Pathogen control efforts should include: good production practices on the farm, slaughtering of animals that are disease free, processing of carcasses under sanitary and hygienic conditions, use of decontamination intervention strategies to reduce microbial levels on carcasses and fresh meat, thermal processing, drying, fermentation, acidification, use of antimicrobials, maintenance of the cold chain during distribution, and proper storage and preparation by food service and consumers.

This chapter discusses selected aspects of the formation, occurrence, prevention and elimination procedures of contaminants in processed meat products. During the technological and culinary treatment of meat, conditions are favourable for the formation of compounds harmful to human health. Such compounds include polycyclic aromatic hydrocarbons, which can contaminate meat during smoking, grilling and roasting; N-nitroso amines, which may form during salting and thermal treatment; and biogenic amines, which form during ripening. Microbial spoilage of meat products is also an issue. Finally, heterocyclic amines can form in meat and in meat products during frying, barbecuing and grilling. This chapter also includes some data on legislation limits, where these exist, as well as an outline of the analytical procedures, finding and occurrence in various meat matrices.

Molds are present in air, water, and soil and are regularly found on production equipment and in/on dairy products. Spoilage by molds occurs for many cheese types, but yogurt, sour cream, butter, sweetened condensed milk, and other dairy products are also occasionally affected. Visible growth, discoloration, structure disintegration, and off-flavors are the common quality defects. Because some mold species grow at 1–5 °C and tolerate low aw (down to 0.80) and belong to low oxygen tension, they may compete well on or in stored dairy products. Some molds are successful in resisting preservatives (e.g., sorbate). Representative species most often belong to the genus Penicillium; however, Cladosporium, Phoma, Aspergillus, Cephalosporium, Geotrichum, Mucor, Rhizobium, Alternaria, and other species also occur. Mycotoxins may be produced by some spoilage molds, and those of Penicillium and Aspergillus are well described. However, chances of mycotoxin production are very small when dairy products are kept at refrigeration temperatures. Good hygiene practice is very important to fight mold spoilage. Because air is generally an effective vehicle for distribution of mold, filtration of air and even the practice of cleanroom techniques have been introduced in some places. Vacuum-packaging or modified atmosphere packaging is used to inhibit mold growth, and application of chemical inhibitors on wrappings and product surfaces is also used.

A number of factors affect the quality of meat and poultry. Colour is an important quality attribute influencing the consumer’s purchase decision. The oxidation of muscle lipids ultimately leads to off-odours and flavours. The eating quality of meat is affected by tenderness, texture, juiciness and flavour. Microbial contamination and spoilage also have a negative impact on the sensory quality of meat and poultry. This chapter examines the use of non-meat ingredients (sodium chloride (salt), phosphates, lactates, carrageenans, whey protein, soya protein, starch and enzymes) in comminuted and whole cuts of meat and poultry. The influence of such ingredients on the quality and shelf life parameters of meat and poultry was evaluated.

The principal objective of food processing is to preserve the overall quality of the food over a certain duration known as shelf life. While operations such as heat processing, concentration, drying, irradiation, curing, smoking, etc. may serve other purposes, their main objective is, or was historically, to prevent or retard spoilage. This chapter discusses operations that assist to increase shelf life of food materials. Many food products owe their safety and shelf-stability not to a single preservation technique but to the combined effect of a number of mechanisms, acting simultaneously. While each mechanism alone would be insufficient to provide the desired protection, the combination does the job. As an example, one can assume that the shelf life and safety of dry sausage is provided by the combined effect of low water activity, relatively low pH, smoking, salt, low temperature, and perhaps spices, each one of these hurdles being not high enough to achieve the expected preservation when acting alone.