Food processing by high hydrostatic pressure

The use of high hydrostatic pressures (HHP) for food processing is finding increased application within the food industry. One of the advantages of this technology is that because it does not use heat, sensory, and nutritional attributes of the product remain virtually unaffected, thus yielding products with better quality than those processed traditional methods. HHP have the ability to inactivate microorganisms as well as enzymes responsible for shortening the life of a product. In addition to lengthening the shelf-life of food products, HHP can modify functional properties of components such as proteins, which in turn can lead to the development of new products. Equipment for large-scale production of HHP processed products are commercially available nowadays. Guacamole, sliced ham, oysters, and fruit juices are some of the products currently available on the market. HHP technology is one of the most promising nonthermal processes.     

超高压技术在虾类保鲜与加工中的应用

本文通过对国内外利用超高压技术在虾类杀菌、钝化多酚氧化酶、消除过敏原、脱壳、提取虾青素以及对肌肉色泽、p H、水分含量、蛋白质、风味、质构和组织结构的影响等方面的研究进行阐述,深入分析其作用机制和应用前景,并提出今后研究的关键技术与发展方向,为超高压技术在虾类保鲜与加工中的产业化应用提供理论参考。     

The influence of high pressure on bio-system reaction kinetics and the preservation of vitamin C

Producing of safer products by applying high pressure on biosystem, is a novel non-thermal technology with significant results in maintaining the natural characteristics of the food items. Modeling of the microorganism kinetics inactivation by the high pressure was determined and certificated by an experimental approach. It is established that the basic laws of the joint influence of the factors of high pressure, temperature and process time on microorganisms and vitamin C are reproduced in the framework of the linear kinetics. By choosing the values of the process parameters (pressure, temperature, duration of the process), the averaged thermodynamic characteristics of micro flora can be changed, as well as the value of the activation barrier of the biochemical reaction. Based on these results, working 40 min at the pressure 400 MPa, and temperature 300 K, the microorganism activity is minimum, and the vitamin C contain is preserved about 90 percent.     

高压法提取天然色素

本文研究利用高压方法提取植物中的天然色素，以提取番茄中的番茄红素为例，将番茄先进行高压处理，然后用有机溶剂提取番茄红素。在本研究中，最佳的高压条件为：200MPa、3次加压、每次加压15min。在此条件下，前3次的提取量是未经高压处理时的4．8倍。     

Effect of high pressure processing on sugar‐snap cookie dough preservation and cookie quality

In this study, cookie dough was subjected to high pressure processing (HPP) to evaluate the effect of this technology on the microbiological features and on the quality characteristics of both the dough and the cookies. HPP reduced the microbial counts of mesophilic bacteria and yeast/molds. Microbiological inactivation in the cookie dough was maintained for 7 days of storage at ambient temperature suggesting extended shelf‐life of the cookie dough. Cookie dough treated with HPP had higher density. Upon baking the spread rate of HPP treated dough was higher resulting in less baking time. The HPP cookie dough and the corresponding cookies made from them had darker tones compared to the untreated dough. Digital images of cookie surfaces showed that HPP cookies had smoother surface and tiny cracks which were evenly distributed.

Practical applications

The utilization of high pressure for processing represents an opportunity to aid in the preservation and extension of self‐life of cereal products. Cookie dough, traditionally not preserved a room temperature, can be processed by high pressure and stored at ambient temperature. Cookies prepared with high pressured cookie dough spread faster during baking reducing total cooking time significantly, reducing, thus, processing time. Cookie quality characteristics are not significantly affected by high pressure processing.     

超高压技术对病原微生物的杀灭作用

高压杀菌技术是世界食品加工业中的一项高新技术。对食品高压处理技术的产生、发展，高压对病原微生物的影响及食品高压处理技术的应用前景、存在的问题及研究开发的课题作了综述。     

天然淀粉的超高压糊化压力研究

在悬浮液浓度为5%(w/v),温度为(20±2)℃时,对8种不同淀粉进行高压处理5 min使淀粉发生糊化,采用X射线衍射测试技术得到了各种淀粉完全糊化的压力:小麦淀粉和木薯淀粉约为500 MPa,玉米淀粉、荸荠淀粉、糯小麦淀粉和糯米淀粉均为550 MPa,糯玉米淀粉约为650 MPa,马铃薯淀粉为750 MPa.     

Effect of high pressure preservation on the quality of dry cured beef “Cecina de Leon”

Microbiological, physicochemical and sensory quality of “Cecina de León” vacuum packed was evaluated after high pressure treatment (500 MPa, 5 min) and further chilling storage at 6 °C for up to 210 days. The objective was to determine if high pressure processing is a valid preservation method to reduce the growth of spoliage microorganisms without modification of its quality properties along of the chilling storage time for this Spanish beef dried meat product. Since, this product is usually presented to the consumer in vacuum packed slices and cuts, these two retail sale systems were studied. High pressure processing at 500 MPa for 5 min avoided the growth of enterobacteria, enterococci and pseudomonads and delayed the growth of lactic acid bacteria, Micrococcaceae and yeasts and moulds. Besides, no change was found after pressure treatment and during refrigerated storage, in physicochemical and sensory parameters. It could be concluded, on the basis of the results, that the high pressure treatment was an efficient method for preserving the safety of “Cecina de León” without decreasing their sensory properties.Industrial relevanceHigh pressure processing is finding increasing use in the food industry because of its relative advantages versus other food processing methods in eliciting minimal changes in the flavour and nutritional qualities of the final product and in extending the shelf life. The study aimed the evaluation of microbiological, physicochemical and sensory characteristics at vacuum packed slices and cuts of “Cecina de León” during subsequent extended chilled storage. High pressure processing was a valid preservation method to reduce the growth of spoilage microorganisms without any changes on “Cecina de León” quality properties along wide chilled storage.     

高压对肌肉蛋白凝胶性的影响

高压技术对肌肉蛋白的凝胶特性的作用和在食品工业上新的应用这两个方面引起了人们的兴趣,高压对凝胶的稳定作用依赖于蛋白系统本身的特性和高压处理的条件,压力和温度是相关联的两个条件,它们会引起不同的影响,这主要依赖于温度和压力的大小以及它们的作用顺序。综述了影响高压对肌肉蛋白凝胶稳定性的4种不同的温度和压力的组合:(1)在低温和常温对原料肉的高压处理;(2)在高压条件下对原料肉的加热处理;(3)在加热前对原料肉的高压处理;(4)振动或逐步脉冲的高压。     

High‐pressure processing and preservation of food

Abstract

High pressure alone or in combination with other technologies offers great potential for producing foods with natural characteristics. Pressure works independent of size and geometry of food resulting in even preservation. The preservative effect itself is influenced by a number of factors with different foods requiring different levels of pressure. Various microorganisms also vary in their response to high pressure and the effect depends on the physical state of the microorganism and the composition of the medium. Because enzymes have a high resistance to pressure, enzymatic and oxidative spoilage are the major limiting factors in shelf‐life extension of pressure‐processed foods. This paper briefly reviews the effects of high pressure on various foods, enzymes, and microorganisms; and discusses some of the advantages and disadvantages associated with the use of this technology.     

Bacterial inactivation by high-pressure homogenisation and high hydrostatic pressure

The resistance of five gram-positive bacteria, Enterococcus faecalis, Staphylococcus aureus, Lactobacillus plantarum, Listeria innocua and Leuconostoc dextranicum, and six gram-negative bacteria, Salmonella enterica serovar typhimurium, Shigella flexneri, Yersinia enterocolitica, Pseudomonas fluorescens and two strains of Escherichia coli, to high-pressure homogenisation (100-300 MPa) and to high hydrostatic pressure (200-400 MPa) was compared in this study. Within the group of gram-positive bacteria and within the group of gram-negative bacteria, large differences were observed in resistance to high hydrostatic pressure, but not to high-pressure homogenisation. All gram-positive bacteria were more resistant than any of the gram-negative bacteria to high-pressure homogenisation, while in relative to high hydrostatic pressure resistance both groups overlapped. Within the group of gram-negative bacteria, there also existed another order in resistance to high-pressure homogenisation than to high hydrostatic pressure. Further it appears that the mutant E. coli LMM1010, which is resistant to high hydrostatic pressure is not more resistant to high-pressure homogenisation than its parental strain MG1655. The preceding observations indicate a different response of the test bacteria to high-pressure homogenisation compared to high hydrostatic pressure treatment, which suggests that the underlying inactivation mechanisms for both techniques are different. Further, no sublethal injury could be observed upon high-pressure homogenisation of Y. enterocolitica and S. aureus cell population by using low pH (5.5 7), NaCl (0 6%) or SDS (0-100 mg/l) as selective components in the plating medium. Finally, it was observed that successive rounds of high-pressure homogenisation have an additive effect on viability reduction of Y. enterocolitica and S. aureus.     

利用一次高压喷射液化法生产系列大米麦芽糖浆

采用一次高压喷射、两次加酶完成液化的工艺，通过控制液化DE值，添加不同的酶制剂糖化，可生产不同类型的麦芽糖浆，残渣生产高蛋白粉。该工艺淀粉的转化率高达96％以上。     

Promoting structure formation by high pressure in gluten-free flours

In order to evaluate the potential of high pressure (HP) treatment to improve the functional properties of gluten-free flours, the effect of HP on the rheological properties of three gluten-free batters was investigated. Buckwheat, white rice and teff batters (40 g/100 g) were treated for 10 min at 200, 400 or 600 MPa. Changes in the microstructure of the batters after HP-treatment were observed using scanning electron microscopy. Pasting profiles revealed HP-induced starch gelatinisation. Furthermore, Lab-on-a-Chip capillary gel electrophoresis revealed protein polymerisation by thiol/disulphide-interchange reactions in white rice and teff batters. For buckwheat proteins however, no such cross-linking mechanism was observed, which was explained by the absence of free sulfhydryl groups. An increase in viscoelastic properties at higher pressures was observed, and could be explained by the modifications occurring in starch and protein structure. Overall, this study has shown that HP-treatment has the potential to improve functional properties of gluten-free batters.     

Preservation of fatty duck liver by high pressure treatment

Fatty liver samples from duck were treated with high pressures and packaged in multilayer films. Microbiological analysis, permeability of the films to oxygen and fat loss, caused by melting, were assessed after pressure or thermal treatment. Microbiological analysis showed a noteworthy reduction in the total aerobic mesophilic flora and eradication of the coliform flora, whichever film or treatment was used. Nevertheless, a significant bacterial flora was observed during storage at 4 °C from 42 days with a polyethylene/polyamide/polyethylene film and a sample which had been treated with pressure. But, treatment at 550 MPa for 55 °C and 20 min, in combination with two low oxygen permeability films (ethylene and vinyl alcohol copolymer) gave a product with long storage life (90 days) at 4 °C and a significant reduction in the melting of lipids.     

超高压提取葡萄籽总黄酮的研究

利用超高压技术提取葡萄籽中黄酮类化合物。在单因素实验的基础上,采用正交实验法对葡萄籽中黄酮类化合物的超高压提取工艺进行优化,以总黄酮的提取率为指标,用分光光度法测定其含量。得到最佳工艺条件为:乙醇体积分数75%、提取压力325MPa、保压时间6min、提取温度50℃、料液比1:35(g/mL),优选结果经验证实验,获得较高得率为7.29%。     

Pasteurization of food by hydrostatic high pressure: chemical aspects

Food pasteurized by hydrostatic high pressure have already been marketed in Japan. There is great interest in this method also in Europe and USA. Temperature and pressure are the essential parameters influencing the state of substances including foods. While the influence of temperature on food has been extensively investigated, effects of pressure, also in combination with temperature, are attracting increasing scientific attention now. Processes and reactions in food governed by Le Chatelier's principle are of special interest; they include chemical reactions of both low- and macromolecular compounds. Theoretical fundamentals and examples of pressure affected reactions are presented.

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Zusammenfassung Mit Hilfe hydrostatischen Hochdrucks pasteurisierte Lebensmittel werden in Japan bereits vermarktet. Auch in Europa und USA ist das Interesse an dieser Methode groß. Temperatur und Druck sind die wichtigsten Parameter, die den Zustand der Materie -auch von Lebensmitteln — beeinflussen. Während die Einwirkung von Temperatur auf Lebensmittel seit langem Gegenstand von Untersuchungen ist, ist der Einfluß des Druckes auch in Kombination mit Temperatur auf Lebensmittel ein relativ junges Forschungsgebiet. Generell sollten Vorgänge und Reaktionen in Lebensmitteln untersucht werden, die dem Prinzip von Le Chatelier unterliegen. Hierzu gehören chemische Reaktionen niedermolekularer und makromolekularer Verbindungen. Es werden theoretische Grundlagen und Beispiele für durch Druck beeinflußte Reaktionen vorgestellt.

     

谈低压法高纯度液体二氧化碳的生产

CO2是发酵法酒精的副产品。每生产100g酒精理论上同时生成95．5gCO2。由于不可避免的损失，实际可以回收的CO2约40—65g(因酒精生产的工艺而异)。国内实际达到的最高回收量约48g(1988．上海)。改造前我厂一直采用传统的高压法回收CO2，质量差、产量低、经济效益少。年产CO2 1500t，回收率只有5％。大量本来可以回收的CO2白白放空浪费了。     

Physiological damages of Listeria monocytogenes treated by high hydrostatic pressure

A fluorescent glucose analogue, 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose (2-NBDG), which had been developed previously for the analysis of glucose uptake activity by living cells, was investigated to evaluate its applicability for assaying the viability of yeasts. Fluorescence intensities of the yeast population were measured by fluorescence spectrophotometry upon exposure to antifungal agents after staining with 2-NBDG and were compared to the number of colony forming units (CFU). A good correlation was obtained between the yeast viability, determined by the CFU, and the accumulation of 2-NBDG by yeast cells (correlation constant: r=0.98). Susceptibility testing of amphotericin B and miconazole against yeast strains by plate count and 2-NBDG fluorescence method yielded corresponding results. In conclusion, we found that staining with 2-NBDG is a rapid and sensitive method for the assessment of yeast cell viability.     

壳聚糖的高压均质降解动力学研究

采用高压均质技术(piston-gap型高压均质机)降解壳聚糖,考察循环次数及原料相对分子质量对其降解效果的影响,研究高压均质降解动力学,探讨其降解产物相对分子质量与循环次数之间的关系。结果表明:高压均质降解效果随循环次数的增加及原料相对分子质量的增大而提高;壳聚糖的高压均质降解过程遵循一级反应动力学;壳聚糖降解产物的相对分子质量与循环次数之间存在函数关系。