Food safety, particularly with reference to microorganisms, is a critical matter for human life so that technology and systems for food sterilization and pasteurization to prevent the occurrence of contamination, spoilage and foodborne illness by harmful microorganisms need to be established on a scientific basis. For the future in the 21^st century, construction of a novel foundation is a high priority. In this preface of the present special issue related to such food processes, the author's opinions on several problems and proposals are presented from three viewpoints. First, from the scientific aspect, we need to clarify the question of why and how microorganisms are killed by physical and chemical treatments. Second, from the technological aspect, the concept of interactions among three fundamental elements, food, technology and microorganisms, require quantitative characterization and a synthesis for practical application in a user-friendly style. Finally, from the aspect of systems for the control of harmful microorganisms, HACCP (hazard analysis and the critical control point) and risk assessment have evolved. For further development, a novel theoretical basis should be constructed to accompany ongoing studies in predictive microbiology. In addition, the author focuses on establishment if institutional and organizational elements to facilitate fundamental research and development in the science and technology of microorganism control, including food sterilization and pasteurization.

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This overview concerns injured microbes occurring after pasteurization of food and sanitization of manufacturing environments, focusing on definitions, properties and means of detection. When microbial cells are exposed to a relatively mild physical or chemical stress, they may be sublethally injured and then recover through repair during subculture after treatment. Besides the general model of sublethal injury, we propose a basal model covering not only sublethally injured but also lethally injured cells. It should be noted that a comprehensive approach to cell injury should be employed, considering qualitative as well as quantitative aspects, because even with one stress two or more injury pathways are likely. To detect and count injured cells, cultivation and non-cultivation methods, with multiplication and non-multiplication approaches, should take into account primary and secondary injury processes. The plate count (colony counting) method is a classical but one of the most effective tools for assay of injured cells along with the differential plating method. As a representative non-culture method, staining of cells with two fluorescent dyes having different staining principles, such as CFDA and PI, can be cited. Occurrence of injured cells depends upon the balance of reaction rates between injury and death kinetics. Also in the physiological sense, occurrence and properties of injured cells vary markedly with the kind of stressor, whether it be heat, irradiation, high hydrostatic pressure, low pH, disinfectants or others. In conclusion, injured microbes are in an unstable or metastable state, different from viable but non-culturable bacteria, biofilm cells, spores and even growing cells, all of which are in physiologically stable state. Finally we describe a mini-history of research into injured microbes in Japan and also introduce the activity of the Japanese Research Society of Injured Microbes, which was established in April 2016.

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Approximately 80 % of the microbial flora in vegetables are bacteria, whose counts vary widely within and among vegetable types. These epiphytic bacteria are mostly phytopathogenic and soilborne organisms that do not usually present a public health concern. However, many opportunities for potential pathogenic cross-contamination of produce exist from production through shipping, and some foodborne pathogens can survive and grow on fresh and fresh-cut vegetables. Washing produce with sanitizers is an important step to reduce the microbial population after harvesting and during the processing of fresh-cut vegetables. A 100 to 200 ppm chlorine solution prepared from sodium hypochlorite is widely used in the food industry, but high concentrations of this agent for increased effectiveness may cause off-odor, nutrient loss, and formation of toxic by-products. The Japanese have devised alternatives to sodium hypochlorite such as electrolyzed acidic water, including strongly acidic (pH < 2.7, 20–60 ppm of available chlorine), weakly acidic (pH 2.7–5.0, 10–60 ppm), and slightly acidic (pH 5.0–6.5, 10–80 ppm) variants and ozonated water (1–10 ppm) that are used in some commercial plants. Treatments with either electrolyzed acidic or ozonated water were effective in reducing microbial counts on fresh-cut vegetables by 0.5 to 2 log relative to the tap water-rinsed control, without quality loss. In addition to these disinfectants, natural antimicrobial agents derived from plants and animals such as ferulic acid, calcind calcium, fumaric acid, and mustard and hop extracts reduced the microbial counts on fresh-cut vegetables by 0.3 to 1 log as compared to tap water-dipped controls. Treatments combining the disinfectant and antimicrobial agent have demonstrated increased effectiveness due to synergism. On fresh-cut lettuce, antimicrobial effects were greater with treatment of electrolyzed acidic water followed by fumaric acid agent than that of fumaric acid agent followed by electrolyzed acidic water. However, the former treatment induced a sour taste with fresh-cut lettuce, thus the agent with subsequent washing treatment should be better. Therefore, it is important to understand which disinfectant and agent are best for commercial use with each individual fresh-cut vegetable. Future trends regarding eliminating foodborne pathogens and persistent spore-former microbes from fresh and fresh-cut vegetables include physical treatment with hot water, superheated vapor, and high-pressure, alone or in combination with chemical sanitization. In addition, the presence of bacteria injured sublethally by sanitizers on fresh and fresh-cut vegetables must be taken into account for evaluating microbiological quality and safety of produce.

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Since novel food processing by high hydrostatic pressure (HHP) was first commercialized for jam products in Japan in 1990, the market for HHP-processed foods has been growing year by year. Most of the efforts for practical HHP food processing have been devoted to effective microbial inactivation.

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Foods and foodstuffs must be decontaminated by killing putrefactive and food poisoning microorganisms to maintain wholesomeness. In addition, they must be protected by suitable packaging materials during distribution to the market to prevent microbial contamination from the immediate environment. For this reason it is essential to sterilize packaging materials, too. Sterilizing the containers for aseptic packaging by germicides causes concerns about unwanted persistence and much effort is required for complete removal. Ultraviolet light and ionizing radiation have been utilized to control microorganisms. Of particular interest, electron beams from electron accelerators have higher penetration power than UV, and have already been widely put to practical use in sterilization of medical devices together with Co-60 gamma rays. Radiation sterilization has been expanded to cover packaging materials for aseptic packaging, such as the large capacity thick bag-in-box (BIB) used for liquid food transport, pharmaceutical packaging, such as eye drop containers, plastic caps for PET bottles and containers for beverages, plastic disposable trays and containers for dairy products. The use of irradiation sterilization has grown year after year, for example reaching the economic scale of 20 billion yen in 2007. More recently, low-energy electron beams less than 1 MeV, which have been applied for curing and cross-linking of polymers, have been attracting attention as a means of sterilizing packaging materials because they can be employed without radiation control under the Japanese Act on Prevention of Radiation Disease Due to Radioisotopes. Practical use of low energy electrons for germfree filling of beverages into PET bottles has already started and great expansion can be expected in the future.

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Recognizing the importance of quality control and knowledge of food manufacturing processes and distribution networks is essential for application of the HACCP system. Microbial control based on the hurdle technology theory is most important to maintain food-safety in Japan. Meanwhile, in the field of heat sterilization, both process operators and auditors need to be flexible to control residual microorganisms after pasteurization at low-temperature.

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Soymilk is one of those remarkable beverages, as well as material for tofu making. It contains almost 4 % protein, which has a good amino acid balance and health benefits. For soymilk making, the first step is commonly imbibition of the soybeans. Removing the imbibition step is expected to show some merits such as a decrease in the risk of microbial growth, cutting down water waste from imbibition and saving imbibition time. So the effect of removing the imbibition step on soymilk making was examined. Namely, non-imbibed soybeans (whole beans) were milled with the necessary amount of water in a blender under various conditions (revolution of blender and milling time) to prepare soymilk with no imbibition. Yield of the soymilks were almost equivalent between non-imbibed and imbibed beans, but solid content was lower in non-imbibed beans at low revolution of the blender. With increasing revolution, solid content increased and finally became almost equivalent to that prepared from imbibed beans. Thus, removing imbibition is thought to have only a slight effect on dispersion of soymilk and to be effective for improving soymilk processing conditions. Soymilk for beverages is quite different from that for tofu making. The soymilk for beverages is produced by milling imbibed or non-imbibed seeds at high temperature. High temperature milling is used to inactivate lipoxygenase, which is known to cause beany flavor. So soymilk prepared by high temperature milling was then characterized to analyze precipitation, denaturation and protein aggregation. For the result, milling at temperatures from 70 to 80 ℃ allowed precipitation and denaturation to increase and accelerate growth of aggregates, but over 80 ℃ , the size of protein aggregates decreased and were more dispersible. In addition to inactivating the lipoxygenase, milling over 80 ℃ was also shown to improve dispersion of soymilk. By replacing water bath heating with a Joule heating device, soymilk is shown to be much more rapidly and exactly heated. Using the Joule heating device, soymilk was prepared with various heating rates. For the results, heating rate affected the quality of soymilk and also tofu curd derived from the soymilk. An increase in heating rate decreased precipitation and viscosity. From the above data, processing conditions, such as imbibition, milling and heating are thought to greatly affect quality of soymilk. Further investigation on processing of soybean is thought to be important in the future.

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Introduction
“Green Odor” emitted by leaves is composed of six unsaturated C6 alcohols and aldehydes with Z- or E-double bonds and two saturated compounds. In response to environmental stimuli, neutral fat, phospho-and galacto-lipids in chloroplasts are hydrolyzed by lipolytic acyl hydrolase to yield α-linolenic and linoleic acids. Then, by lipoxygenase and the hydroperoxide lyase, these acids yield (Z)-3-hexenal and n-hexanal via unstable (S)-13-hydroperoxide intermediates. Finally, by alcohol dehydrogenase these aldehydes are reduced to corresponding alcohols. On the other hand, pyrethrin activity is induced by an original blend of “Green Odor” and (E)-β-farnesene and is formed finally by Lipase/Esterase from chrysanthemoyl CoA and pyrethrolone, respectively. Namely, the pyrethrin forming activities are exactly controlled by the blend ratio of “green odor” and the terpene. This unexpected original finding means that the “Green Odor” is a very important messenger of plant origin.

“Green Odor”
This article describes components, biosynthesis and seasonal changes of the green odor. Green odor emitted by leaves is composed of six unsaturated C6-alcohols, -aldehydes with Z- or E-double bond and two saturated compounds. In these homologues, (E)-2- hexenal is named “leaf aldehyde”, whereas (Z)-3- hexenol is referred to as “leaf alcohol”. Leaf aldehyde was found in fresh green leaves of certain bushes by Curtius T. at Heidelberg University in 1912. Meanwhile, Leaf alcohol was found in fresh tea leaves by my teacher Takei S. at Kyoto University in 1933. In 1960 and 71, I found ｓ(E)-3- and (E)-2-hexenols and then in 1973 and 81, I found (Z)- and (E)-3-hexenals from fresh tea leaves. These eight compounds are collectively regarded as “Green odor”. Until today I have investigated them from a multi disciplinary approach of organic chemistry, biochemistry, molecular biology, aroma-physiology and -psychology.
At first, in the biosynthetic pathway of green odor it should be noted for the unexpected findings that the precursor of green odor does not possess six carbons, such as glucoses, but eighteen carbons; α-linolenic (1) and linoleic acids (2). In response to various environmental stimuli, neutral fat, phospho- and galacto-lipids in tea chloroplasts are hydrolyzed by lipolytic acylhydrolase to result in (1) and (2). Then, by lipoxygenase (LOX) these acids are converted to unstable (S)-13-hydroperoxide-intermediates. Following that, by hydroperoxide lyase (HPO lyase) the cleavage of the single bond between carbon-12 and -13 of these intermediates results in (Z)-3-hexenal and n-hexanal. By alcohol dehydrogenase these aldehydes are reduced to corresponding alcohols. It should be noted that the pathway from lipids to (Z)-3-hexenal is a one way reaction, whereas the alcohol-aldehyde redox reaction is an equilibrium. By this equilibrium the concentration balance between six unsaturated alcohols and aldehydes should result in induced bioactive function. Particularly, the lipoxygenase reaction passes through the complex stereochemical steps, that is the removal of a H proton from C11 in α -linolenic acid to form an (S)-13-hydroperoxide-intermediate. This stereochemical coordination is left rotation of R1->R2->R3- bound to asymmetric carbon-13. (Z)-3- and (E)-2-hexenals produced by LOX and HPO lyase differ largely by plant species.
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In the pre-farming period, wild acorns, potatoes and herbs were the most important foodstuffs for our ancestors. The main nutritional component of acorns and potatoes is starch, and they were the staple foodstuffs, while those of herbs are vitamins, minerals and dietary fiber, and they were the subsidiary foodstuffs. But the potatoes and herbs contain harsh components such as alkaloids, saponins, tannins, organic and inorganic salts, and the acorns alone contain tannins with an astringent taste. The harsh components are water-soluble components in the vacuoles of cells. People changed the wild materials to edible foodstuffs by removing harshness with techniques of water-extraction, heat-treatment or dilute acid and alkali-treatment, etc. But the starchy foodstuffs must be heated below 60 ℃ , because the onset temperature of starch gelatinization is about 60 ℃ . Further, the acorns are a nut with a hard pericarp and the tannins are contained in the cotyledon of the seeds. Therefore, people need to grind acorns with a mortar and pestle before removal of tannins. They established the techniques of removal of tannins from the acorns though trial and error.

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