Microwave processing techniques and their recent applications in the food industry
TL;DR: In this article, a review focusing on recent applications of microwave processing technologies including microwave drying, heating, and sterilizing in fruit (banana, apple, olive, sour cherries, pomegranate arils, blueberries, kiwifruit, aronia, strawberry, and grape tomato), vegetables (potato, bamboo shoot, purslane leaves, onion, green bean, pumpkin, eggplant, edamame, sea tangle, garlic, kale, red cabbage, tomato, cassava, lentils, chickpea, broccoli, Brussels spr
Abstract: Background Microwave processing techniques have been extensively used in the food industry due to its significant reduction in cooking time and energy consumption. Microwave processing technologies such as microwave drying, heating and sterilizing play a significant role in food quality and safety control. However, few reviews have been published in recent years summarizing the latest developments in the application of microwave technology in the food industry. Scope and approach This review focuses on recent applications of microwave processing technologies including microwave drying, heating, and sterilizing in fruit (banana, apple, olive, sour cherries, pomegranate arils, blueberries, kiwifruit, aronia, strawberry, and grape tomato), vegetables (potato, bamboo shoot, purslane leaves, onion, green bean, pumpkin, eggplant, edamame, sea tangle, garlic, kale, red cabbage, tomato, cassava, lentils, chickpea, broccoli, Brussels sprouts, cauliflower, jalapeno peppers, and coriander foliage), and meat products (sardine fish, restructured silver carp slices, sea cucumber, beef semitendinosus muscle, bovine supraspinatus muscle, camel longissimus dorsi muscle, foal meat, bovine gluteus medium muscle, chicken steak, mature cows semimembranosus and semitendinosus muscles, kavurma (a ready-to-eat meat product), salmon, cod, drumettes, and beef slices), changes in product quality as affected with microwave processing are discussed in details, and future directions of research are presented. Key findings and conclusions Microwave drying has the advantages of low energy consumption and high efficiency as compared to conventional drying, while producing more porous structure of foods. Microwave drying usually combines with other conventional drying to enhance the quality of a food product. Compared with the traditional method, microwave heating or cooking can generally retain higher levels of bioactive components, antioxidant activity and attractive color of vegetables, while microwave cooking with water can cause a serious drop in nutrients due to leaching and thermal liability. Microwave sterilization has the capacity to completely inactivate microorganisms and effectively destroy enzyme activity, and less effect on antioxidant activity, texture and color of food products compared with conventional pasteurization.
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TL;DR: It was concluded that there are no best activating agents; rather, each agent reacts uniquely with a precursor, and the optimum choice depends on the target adsorbent.
Abstract: The choice of activating agent for the thermochemical production of high-grade activated carbon (AC) from agricultural residues and wastes, such as feedstock, requires innovative methods. Overcoming energy losses, and using the best techniques to minimise secondary contamination and improve adsorptivity, are critical. Here, we review the importance and influence of activating agents on agricultural waste: how they react and compare conventional and microwave processes. In particular, adsorbent pore characteristics, surface chemistry interactions and production modes were compared with traditional methods. It was concluded that there are no best activating agents; rather, each agent reacts uniquely with a precursor, and the optimum choice depends on the target adsorbent. Natural chemicals can also be as effective as inorganic activating agents, and offer the advantages that they are usually safe, and readily available. The use of a microwave, as an innovative pyrolysis approach, can enhance the activation process within a duration of 1–4 h and temperature of 500–1200 °C, after which the yield and efficiency decline rapidly due to molecular breakdown. This study also examines the biomass milling process requirements; the influence of the dielectric properties, along with the effect of washing; and experimental setup challenges. The microwave setup system, biomass feed rate, product delivery, inert gas flow rate, reactor design and recovery lines are all important factors in the microwave activation process, and contribute to the overall efficiency of AC preparation. However, a major issue is a lack of large-scale industrial demonstration units for microwave technology.
165 citations
Cites background from "Microwave processing techniques and..."
...Progress in the food area seems to have continued, with microwaves being used in particular for lower-temperature applications, such as drying, although interestingly, even for this type of application, there are issues with the formation of hot spots [203]....
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TL;DR: In this paper, the effects of electric fields and electromagnetic wave including pulsed electric field, microwave, radio frequency and gamma irradiation on the changes in food protein structure (primary, secondary, tertiary and quaternary) and functionality (solubility, apparent viscosity, emulsifying, foaming, and gelling properties).
Abstract: Background Protein is an essential component of human diet and can be applied to many aspects in food systems due to its abundant nutritional value and functional properties. There are many physical methods that have been used to modify the inherent structure of protein to expand its application areas in the food industry. Among them, electric fields and electromagnetic wave technologies have attracted increasing attention on their abilities to modify food protein structure and functionality, due to the advantages of energy efficiency, food safety and minimal loss of nutrients. Scope and approach The current review presents the effects of electric fields and electromagnetic wave including pulsed electric field, microwave, radio frequency and gamma irradiation on the changes in food protein structure (primary, secondary, tertiary and quaternary) and functionality (solubility, apparent viscosity, emulsifying, foaming, and gelling properties). The affecting factors such as protein concentration and pH, and the strength and duration of electric fields and electromagnetic wave on the mechanisms and effectiveness of changes in protein structure and functional properties are introduced, and the advantages and limitations of these technologies for protein modification are also discussed. Key findings and conclusions Applications of electric fields and electromagnetic wave can induce the conformational changes of protein via the creation of free radicals or larger or smaller molecules, damaging the primary, secondary, tertiary and quaternary structure of protein, and thus influence the functional properties. Therefore electric fields and electromagnetic wave are useful methods to modify food protein structure and functionality for the food industry, and active researches focus on multi-technology corporations for modifying protein structure are urgently required.
109 citations
17 Aug 2020
TL;DR: In this article, the effect of NTP and plasma-treated water (PTW) on seed germination and growth enhancement is discussed, as well as the change in biochemical analysis, e.g., the variation in phytohormones, phytochemicals, and antioxidant levels of seeds after treatment with NTP.
Abstract: In recent years, non-thermal plasma (NTP) application in agriculture is rapidly increasing. Many published articles and reviews in the literature are focus on the post-harvest use of plasma in agriculture. However, the pre-harvest application of plasma still in its early stage. Therefore, in this review, we covered the effect of NTP and plasma-treated water (PTW) on seed germination and growth enhancement. Further, we will discuss the change in biochemical analysis, e.g., the variation in phytohormones, phytochemicals, and antioxidant levels of seeds after treatment with NTP and PTW. Lastly, we will address the possibility of using plasma in the actual agriculture field and prospects of this technology.
86 citations
TL;DR: In this article, the impact and interaction mechanism of food components under additional treatments by innovative technologies has not been well-discussed in the present literatures and the authors aim to summarize recently available information regarding the impact of innovative food processing technologies on several main food components (i.e. protein, polysaccharide and polyphenol), as well as their interactions or complexation with other natural products in model systems.
Abstract: Backgrounds Innovative food processing technologies including ultrasound, microwave and high-pressure treatment have been widely applied for preservation and valorization of nutrients in food resources with high efficiency. However, these treatments are also reported to induce modifications and interactions of food components. The impact and interaction mechanism of food components under additional treatments by innovative technologies has not been well-discussed in the present literatures. Scope and approach This study aims to summarize recently available information regarding the impact of innovative food processing technologies on several main food components (i.e. protein, polysaccharide and polyphenol), as well as their interactions or complexation with other natural products in model systems. In this regard, the data published in literatures were retrieved and the effects of ultrasound, microwave, high pressure homogenization and high hydrostatic pressure on food components were mainly presented. Key findings and conclusions Ultrasound, microwave and high-pressure treatments can modify the physicochemical and functional properties of food components with different effects, depending on processing parameters, conditions and food matrix. The modification of food components induced by innovative technologies treatment may be promising or unwilling. By processing conditions monitoring and adjusting, interaction of food components can be promoted without destroying the primary structures of the compounds.
79 citations
TL;DR: Microwave-assisted thermal sterilizsation technology has promising potentials and has been expected to have comparable results if not better to retorting in sterilization while ensuring better sensory qualities and attribute that influence consumer acceptance.
Abstract: Microwave-assisted thermal sterilizsation (MATS) technology combines the energy from microwaves of long-wavelength (915 MHz) along with hot water immersion to sterilize food in polymeric packages. MATS is presumed to be a successful sterilization method to eliminate pathogens including bacterial spores, improve the shelf-life of food products while the nutritive qualities and flavours are not affected (within consumer acceptance). From the regulatory point of view, it is a thermal technology for pre-packaged commercial sterilization of homogeneous and nonhomogeneous foods as accepted by the Food and Drug Administration (FDA). Scope and approach This review covers the technical progress, advantages and challenges associated with MATS technology with a comparison to conventional methods and its potential in the food industry. This comprehensive background study is worth considering while developing protocols and validation assays for MATS. Key findings MATS is postulated to not only eliminate the edge-heating issues, but it also reduces the heat exposure time to minimize the effect on heat-sensitive components while achieving maximum microbial inactivation. MATS technology has promising potentials and has been expected to have comparable results if not better to retorting in sterilization while ensuring better sensory qualities and attribute that influence consumer acceptance. Hence, bridging the gaps with enhanced efforts in the field of food safety and sensory science would not only provide an upper hand to the technology but would also increase commercialization by meeting the market needs.
75 citations
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TL;DR: In this paper, the microwave-assisted processes in which carbon materials are produced, transformed or used in thermal treatments (generally, as microwave absorbers and catalysts) are reviewed and compared with those obtained by means of conventional (non-microwave-assisted) methods in similar conditions.
866 citations
TL;DR: In this paper, various applications of microwave food processing such as microwave cooking, microwave pasteurization and microwave assisted drying were extensively reviewed and the advantages and the factors affecting the microwave cooking of food materials have been reviewed.
673 citations
TL;DR: In this paper, the authors summarized their results and the solutions offered by them to lessen the non-uniformity of heating and highlighted the current applications of microwave energy in the industrial sector.
Abstract: Use of microwaves has increased largely in the domestic household in the last few decades due to the convenience of using microwave ovens. In the industrial sector, microwave processing is used in some of the unit operations, while it is yet to capture a major place in the industrial applications. The major drawback associated with microwave heating is the non-uniform temperature distribution, resulting in hot and cold spots in the heated product. The non-uniform temperature distribution not only affects the quality of the food but also raises the issue of food safety when the microorganisms may not be destroyed in the cold spots. The temperature distribution during microwave heating has been studied in a wide variety of products by several researchers. This paper summarizes their results and the solutions offered by them to lessen the non-uniformity of heating. The current applications of microwave energy in the industrial sector are also highlighted.
393 citations
TL;DR: In this article, the effect of microwave power during the vacuum-microwave drying (VMD) on sour cherries in terms of drying kinetics, includ- ing the temperature profile of dried material, as well as on some quality factors of the finished product including phenolic compounds, antioxidant capacity, and color.
Abstract: The aim of this study was to determine the effect of microwave power during the vacuum-microwave drying (VMD) on sour cherries in terms of drying kinetics, includ- ing the temperature profile of dried material, as well as on some quality factors of the finished product including phenolic compounds, antioxidant capacity, and color. The content of phenolic compounds, antioxidant activity, and color change were used as quality indicators of dried sour cherries. Sour cherries were dehydrated by convective drying (CD) at tem- peratures of 50 °C, 60 °C, and 70 °C and by VMD at the initial microwave power of 240 W, 360 W, and 480 W reduced to 240 W and 120 W in order to avoid a rapid increase in temperature at the critical moisture content of ca. 1 kg/kg dry mass. Control samples were prepared by freeze drying (FD). The increase in air temperature during CD as well as the increase in material temperature during VMD deteriorated dried product quality in terms of the content of phenolic compounds, antioxidant activity, and color, which was consis- tent with anthocyanins content. However, VMD turned out to be much better than CD and competitive to FD. The best quality of the dried product and its more attractive color were achieved at VMD at 480 W followed by drying at microwave power reduced to 120 W, which corresponds to anthocyanins content. In addition, the drying process had a positive impact on contents of quercetin and keampferol derivatives. Dried sour cherries have a long shelf life and therefore may be a fine alternative to fresh fruit all year round.
296 citations
TL;DR: The overall results of this study demonstrate that fresh Brassica vegetables retain phytochemicals and TAC better than frozen samples.
Abstract: This study evaluated the effect of common cooking practices (i.e., boiling, microwaving, and basket and oven steaming) on the phytochemical content (carotenoids, chlorophylls, glucosinolates, polyphenols, and ascorbic acid), total antioxidant capacity (TAC), and color changes of three generally consumed Brassica vegetables analyzed fresh and frozen. Among cooking procedures, boiling determined an increase of fresh broccoli carotenoids and fresh Brussels sprout polyphenols, whereas a decrease of almost all other phytochemicals in fresh and frozen samples was observed. Steaming procedures determined a release of polyphenols in both fresh and frozen samples. Microwaving was the best cooking method for maintaining the color of both fresh and frozen vegetables and obtaining a good retention of glucosinolates. During all cooking procedures, ascorbic acid was lost in great amount from all vegetables. Chlorophylls were more stable in frozen samples than in fresh ones, even though steaming methods were able to bet...
245 citations