Application of nonthermal processing technologies in extracting and modifying polysaccharides: A critical review

Polysaccharides are natural polymer compounds widely distributed in plants, animals, and microorganisms, most of which have a broad spectrum of biological activities to promote human health. They could also be used as texture modifiers in food industry due to their excellent rheological and mechanical properties. Many researchers have shown that nonthermal processing technologies have numerous advantages, such as high extraction efficiency, short extraction time, and environmental friendliness, in the extraction of polysaccharides compared with the traditional extraction methods. Moreover, nonthermal technologies could effectively change the physicochemical properties and structural characteristics of polysaccharides to improve their biological activities or processing properties. Therefore, a comprehensive summary about the extraction and modification of polysaccharides by nonthermal technologies, including ultrasound, high hydrostatic pressure, pulsed electric fields, and cold plasma, was provided in this review. In particular, the underlying mechanisms, processing operations, and current application status of these technologies were discussed. In addition, the applications of combining nonthermal techniques with other technological methods in polysaccharide extraction and modification were briefly introduced.     

Application of High-Intensity Pulsed Electrical Fields in Food Processing

High-intensity pulsed electric fields (HIPEF) treatment is gaining popularity as a nonthermal processing technology due to its instant penetration characteristics and short processing time. It is evolving as a potential alternative to other thermal and chemical unit operations in food processing. In recent years, numerous research groups have demonstrated the possibility of inactivation of a range of microorganisms and food quality-related enzymes. This article focuses on the potential to use the HIPEF treatment as a preservation technology and as an adjunct to other processing steps, such as extraction, osmotic dehydration, air dehydration, and rehydration.     

Application of High-Intensity Pulsed Electrical Fields in Food Processing

High-intensity pulsed electric fields (HIPEF) treatment is gaining popularity as a nonthermal processing technology due to its instant penetration characteristics and short processing time. It is evolving as a potential alternative to other thermal and chemical unit operations in food processing. In recent years, numerous research groups have demonstrated the possibility of inactivation of a range of microorganisms and food quality-related enzymes. This article focuses on the potential to use the HIPEF treatment as a preservation technology and as an adjunct to other processing steps, such as extraction, osmotic dehydration, air dehydration, and rehydration.     

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.     

Flavonoids in fruits and vegetables after thermal and nonthermal processing: A review

ABSTRACT

Consumers currently demand more nutritious food, which is minimally processed and naturally produced. Flavonoids are one of the major plant metabolites found throughout the plant kingdom, especially in fruits and vegetables. Flavonoids exert tremendous positive effects on health and protect against various diseases. Fruits and vegetables are difficult to store for a long period, owing to their perishable nature even at low temperatures. Therefore, processing is necessary to prolong their shelf lives and increase nutritional values. Thermal processing has been used in the food sector since ancient times. However, nonthermal processing has become more attractive to consumers and product developers recently, owing to the retention of beneficial health properties after nonthermal processing. The present review will address the effects of thermal and nonthermal processing methods such as blanching, drying, high-pressure processing, ultrasound, pulsed electric field, and ultraviolet irradiation on total and individual flavonoid content in fruits and vegetables. In addition, this text will elucidate the stability characteristics as well as bioavailability, cytotoxicity, and transformations of flavonoids during thermal and nonthermal treatments.     

Microbiological Aspects Related to the Feasibility of PEF Technology for Food Pasteurization

Processing unit operations that seek to inactivate harmful microorganisms are of primary importance in ascertaining the safety of food. The capability of pulsed electric fields (PEF) to inactivate vegetative cells of microorganisms at temperatures below those used in thermal processing makes this technology very attractive as a nonthermal pasteurization process for the food industry. Commercial exploitation of this technology for food pasteurization requires the identification of the most PEF-resistant microorganisms that are of concern to public health. Then, the treatment conditions applicable at industrial scale that would reduce the population of these microorganisms to a level that guarantees food safety must be defined. The objective of this paper is to critically compile recent, relevant knowledge with the purpose of enhancing the feasibility of using PEF technology for food pasteurization and underlining the required research for designing PEF pasteurization processes.     

Influence of Innovative Processing on γ‐Aminobutyric Acid (GABA) Contents in Plant Food Materials

Over the last several decades, γ‐aminobutyric acid (GABA) has attracted much attention due to its diverse physiological implications in plants, animals, and microorganisms. GABA naturally occurs in plant materials and its concentrations may vary considerably, from traces up to μmol/g (dry basis) depending on plant matrix, germination stage, and processing conditions, among other factors. However, due to its important biological activities, considerable interest has been shown by both food and pharmaceutical industries to improve its concentration in plants. Natural and conventional treatments such as mechanical and cold stimulation, anoxia, germination, enzyme treatment, adding exogenous glutamic acid (Glu) or gibberellins, and bacterial fermentation have been shown effective to increase the GABA concentration in several plant materials. However, some of these treatments can modify the nutritional, organoleptic, and/or functional properties of plants. Recent consumer demand for food products which are “healthy,” safe and, having added benefits (nutraceuticals/functional components) has led to explore new ways to improve the content of bioactive compounds while maintaining desirable organoleptic and physicochemical properties. Along this line, nonthermal processing technologies (such as high‐pressure processing, pulsed electric fields, and ultrasound, among others) have been shown as means to induce the biosynthesis and accumulation of GABA in plant foods; and the main findings so far reported are presented in this review. Moreover, the most novel tools for the identification of metabolic response in plant materials based on GABA analysis will be also described.     

Valorisation of food wastes to produce natural pigments using non-thermal novel extraction methods: a review

Waste or by-products produced during food processing can be used as a potential source of bioactive compounds including natural pigments. Natural pigments/colourants have numerous health benefits whereas the synthetic colourants have many negative effects on human health. Thus, there is a considerable interest worldwide in pigments extraction from natural sources. Conventional extractions such as soxhlet extraction, water distillation, and solvent extraction have many limitations such as large solvent consumption, long extraction time, and low extraction yields. Therefore, novel techniques such as high pressure, ultrasound, negative pressure and electric field have been employed to assist the pigment extraction process. The novel extraction methods are being developed with the primary aim of higher pigment yield, lower solvent consumption, minimised environmental effects and the convenience of extraction. With this perspective, the present review provides recent insights into the recovery of natural pigments from food wastes/by-products and the application of novel non-thermal technologies for their recovery.     

Application of pulsed electric fields at oil yield and content of functional food ingredients at the production of rapeseed oil

In this study the effect of pulsed electric fields (PEF) on oil yield and content of functional food ingredients of rapeseed (Brassica napus) is discussed. For the analysis hulled and non-hulled rapeseed was used and solvent extraction or pressing for oil separation and oil quality were compared. In dependency of applied PEF treatment intensity (42–84 kJ kg^− 1) oil yield increased by pressing as well as solvent extraction from and higher concentrations of tocopherols, polyphenols, total antioxidants and phytosterols were measured in the oil. No effect on unsaturated properties and saponification values were investigated, and higher concentration of chlorophyll and free fatty acids in the oil were determined. Besides PEF treatment and oil separation method the hulling of rapeseed has an obvious effect on oil quality.Industrial relevanceThe application of pulsed electric fields as a nonthermal food processing technology is interesting for increased extraction processes of plant materials. For consumers gentle processed products get more and more interesting. Results of this study show, that pulsed electric fields can be used as a pretreatment before oil separation to increase oil yield and content of functional food ingredients under gentle conditions.     

花色苷分子结构修饰及其生理活性研究进展

花青素是植物界分布最广、种类众多的一类天然色素,是植物的主要呈色物质,在自然界中多以糖苷（花色苷）的形式存在,具有多种重要的生理功能和生物活性。花色苷具有酚羟基,结构稳定性较差,易受外界条件如pH值、温度、光、O2、金属离子和酶等因素的影响,在食品加工中易分解失去原有的鲜艳颜色,限制了花色苷的贮藏和在食品加工领域中的应用。花色苷分子结构修饰可增加其对外界环境和食品添加剂及食品加工中的稳定性,使其在较大pH值范围内呈现良好色泽。本文系统介绍了不同类型（花色苷酰基化、花色苷酯基化及形成吡喃类衍生物）花色苷结构修饰的原料来源、结构特征及其生理活性,为进一步开展花色苷的结构稳定性与生理活性研究及其在食品加工领域中的护色与应用提供参考。     

Pulsed electric field‐assisted extraction of valuable compounds from microorganisms

Microorganisms (bacteria, yeast, and microalgae) are a promising resource for products of high value such as nutrients, pigments, and enzymes. The majority of these compounds of interest remain inside the cell, thus making it necessary to extract and purify them before use. This review presents the challenges and opportunities in the production of these compounds, the microbial structure and the location of target compounds in the cells, the different procedures proposed for improving extraction of these compounds, and pulsed electric field (PEF)‐assisted extraction as alternative to these procedures. PEF is a nonthermal technology that produces a precise action on the cytoplasmic membrane improving the selective release of intracellular compounds while avoiding undesirable consequences of heating on the characteristics and purity of the extracts. PEF pretreatment with low energetic requirements allows for high extraction yields. However, PEF parameters should be tailored to each microbial cell, according to their structure, size, and other factors affecting efficiency. Furthermore, the recent discovery of the triggering effect of enzymatic activity during cell incubation after electroporation opens up the possibility of new implementations of PEF for the recovery of compounds that are bounded or assembled in structures. Similarly, PEF parameters and suspension storage conditions need to be optimized to reach the desired effect. PEF can be applied in continuous flow and is adaptable to industrial equipment, making it feasible for scale‐up to large processing capacities.     

Enhancing Food Processing by Pulsed and High Voltage Electric Fields: Principles and Applications

ABSTRACT

Improvements in living standards result in a growing demand for food with high quality attributes including freshness, nutrition and safety. However, current industrial processing methods rely on traditional thermal and chemical methods, such as sterilization and solvent extraction, which could induce negative effects on food quality and safety. The electric fields (EFs) involving pulsed electric fields (PEFs) and high voltage electric fields (HVEFs) have been studied and developed for assisting and enhancing various food processes. In this review, the principles and applications of pulsed and high voltage electric fields are described in details for a range of food processes, including microbial inactivation, component extraction, and winemaking, thawing and drying, freezing and enzymatic inactivation. Moreover, the advantages and limitations of electric field related technologies are discussed to foresee future developments in the food industry.

This review demonstrates that electric field technology has a great potential to enhance food processing by supplementing or replacing the conventional methods employed in different food manufacturing processes. Successful industrial applications of electric field treatments have been achieved in some areas such as microbial inactivation and extraction. However, investigations of HVEFs are still in an early stage and translating the technology into industrial applications need further research efforts.     

Toward a Philosophy and Theory of Volumetric Nonthermal Processing

Nonthermal processes for food preservation have been under intensive investigation for about the past quarter century, with varying degrees of success. We focus this discussion on two volumetrically acting nonthermal processes, high pressure processing (HPP) and pulsed electric fields (PEF), with emphasis on scientific understanding of each, and the research questions that need to be addressed for each to be more successful in the future. We discuss the character or “philosophy” of food preservation, with a question about the nature of the kill step(s), and the sensing challenges that need to be addressed. For HPP, key questions and needs center around whether its nonthermal effectiveness can be increased by increased pressures or pulsing, the theoretical treatment of rates of reaction as influenced by pressure, the assumption of uniform pressure distribution, and the need for (and difficulties involved in) in‐situ measurement. For PEF, the questions include the rationale for pulsing, difficulties involved in continuous flow treatment chambers, the difference between electroporation theory and experimental observations, and the difficulties involved in in‐situ measurement and monitoring of electric field distribution.     

高压脉冲电埸在食品加工中的应用前景

高压脉冲电场用于食品加工(杀菌、果蔬榨汁、成分提取等)已有很多研究,因其特有的微观作用机理.是一种非常有前景的新兴技术.综述了近十年来国内外用PEF处理食品的研究.对其进行分类介绍.讨论系统设计的要点.指出工业化需解决的几个问题.     

高压脉冲电场杀菌电力系统的研究

高压脉冲电场用于液态食品杀菌 ,具有时间短、能耗低 ,能有效保存食品营养成份和天然色、香、味特征 ,非常具有工业化应用前途。本文重点介绍高压脉冲电场杀菌电力系统的结构特点和应用。     

New trends in food processing

In this work some of the newest trends in food processing are reviewed. This revision intends to provide an updated overview (including works published until February 2001) on the newest food processes, including food manufacturing, preservation, and control. Modern processes for food and food ingredients manufacturing based on membrane technology, super-critical fluid technology, and some applications of biotechnology are presented, mainly applied to obtain functional foods, "all-natural" enriched foods, probiotics and prebiotics. Also included is a critical assessment concerning non-thermal preservation techniques used for food preservation, such as high hydrostatic pressure, pulsed electric fields, ultrasound, pulsed light, hurdle systems, etc. Finally, a group of new analytical techniques (i.e., molecular techniques such as Polymerase Chain Reaction (PCR), food image analysis, and biosensors) and their use for food and process control is reviewed.     

Natural Pigments: Stabilization Methods of Anthocyanins for Food Applications

The production of natural food pigments continues to grow worldwide. The global market is expected to grow at a compound annual growth rate of 6.22%, by revenue, over the period 2015 to 2019. Pigments such as anthocyanins, carotenoids, betalains, and chlorophylls have been used to color foods. However, there are challenges related to color losses during food processing, storage, and commercialization due to a low stability of natural pigments compared to synthetic colorants. This review summarizes the most recent studies and patents aimed at enhancing anthocyanin stability in food systems. The stabilizing methods include additions of copigment compounds, such as polymers, phenolic compounds, and metals. In addition, the exclusion of O₂ during processing and storage, hard‐panned candy coating methods for blue, green, and brown colors, and various encapsulation techniques were considered. Combining strategies and evaluating new materials capable of stabilizing anthocyanins will enhance their potential for use as value‐added natural food pigments.     

特殊粒色小麦研究进展

特殊粒色小麦富含蛋白质、氨基酸和对人体有益的微量元素和矿物质,具有较好的加工品质,且籽粒中含有较多的天然色素,应用价值和开发潜力较大。从特殊粒色小麦的种植培育、特性、产品开发利用研究现状及存在问题进行综述,对特殊粒色小麦的应用前景进行了展望,以期为拓宽特殊粒色小麦的开发利用途径提供重要的参考依据。     

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.     

非热物理加工新技术对食品品质的影响及应用

阐述了超高压技术、辐照技术、脉冲电场技术、超声波技术等非热物理加工新技术的定义及特点,并综述了这些新技术对食品成分的影响及其在食品加工中的应用。