Red Tomato Products as an Alternative to Reduce Synthetic Dyes in the Food Industry: A Review

Most dyes used in the food industry are synthetic and can be a health hazard. Red tomato may serve as a natural alternative dye to replace synthetic colorants. This study aimed to review the literature on the addition of red tomato products (powder tomato, paste, freeze-dried, tomato peel powder, tomato pomace) to reduce the usage of synthetic dyes in the food industry. Red tomato products have been used as coloring in pasta, bologna, sausages, cookies, crackers, macaroons, hamburgers, breads, muffins, cheeses, and nuggets. The trans-cis isomerization of lycopene by oxidative processes directly affects the color of the pigment. The lycopene contained in tomato has antioxidant activity and could reduce or eliminate other oxidants and/or synthetic preservatives in food. Moreover, tomatoes in foods have high sensory scores, nutritional appeal, and marketing potential. However, its use as a food colorant has been not extensively explored. Therefore, further studies are still required, especially on the stability of carotenoids in tomatoes used in processed foods.     

Synthesis and Application of Rylene Imide Dyes as Organic Semiconducting Materials

Rylene imide dyes have been among the most promising organic semiconducting materials for several years due to their remarkable optoelectronic properties and high chemical/thermal stability. In the past decades, various excellent rylene imide dyes have been developed for optoelectronic devices, such as organic solar cells (OSCs) and organic field‐effect transistors (OFETs). Recently, tremendous progress of perylene diimides (PDIs) and their analogues for use in OSCs has been achieved, which can be attributed to their ease of functionalization. In this review, we will mainly focus on the synthetic strategies toward to latest PDI dyes and higher rylene imide analogues. A variety of compounds synthesized from different building blocks are summarized, and some properties and applications are discussed.     

A Brief History of Colour,the Environmental Impact of Synthetic Dyes and Removal by Using Laccases

The history of colour is fascinating from a social and artistic viewpoint because it shows the way; use; and importance acquired. The use of colours date back to the Stone Age (the first news of cave paintings); colour has contributed to the social and symbolic development of civilizations. Colour has been associated with hierarchy; power and leadership in some of them. The advent of synthetic dyes has revolutionized the colour industry; and due to their low cost; their use has spread to different industrial sectors. Although the percentage of coloured wastewater discharged by the textile; food; pharmaceutical; cosmetic; and paper industries; among other productive areas; are unknown; the toxic effect and ecological implications of this discharged into water bodies are harmful. This review briefly shows the social and artistic history surrounding the discovery and use of natural and synthetic dyes. We summarise the environmental impact caused by the discharge of untreated or poorly treated coloured wastewater to water bodies; which has led to physical; chemical and biological treatments to reduce the colour units so as important physicochemical parameters. We also focus on laccase utility (EC 1.10.3.2), for discolouration enzymatic treatment of coloured wastewater, before its discharge into water bodies. Laccases (p-diphenol: oxidoreductase dioxide) are multicopper oxidoreductase enzymes widely distributed in plants, insects, bacteria, and fungi. Fungal laccases have employed for wastewater colour removal due to their high redox potential. This review includes an analysis of the stability of laccases, the factors that influence production at high scales to achieve discolouration of high volumes of contaminated wastewater, the biotechnological impact of laccases, and the degradation routes that some dyes may follow when using the laccase for colour removal     

Cancer chemoprevention by carotenoids

Carotenoids are natural fat-soluble pigments that provide bright coloration to plants and animals. Dietary intake of carotenoids is inversely associated with the risk of a variety of cancers in different tissues. Preclinical studies have shown that some carotenoids have potent antitumor effects both in vitro and in vivo, suggesting potential preventive and/or therapeutic roles for the compounds. Since chemoprevention is one of the most important strategies in the control of cancer development, molecular mechanism-based cancer chemoprevention using carotenoids seems to be an attractive approach. Various carotenoids, such as β-carotene, a-carotene, lycopene, lutein, zeaxanthin, β-cryptoxanthin, fucoxanthin, canthaxanthin and astaxanthin, have been proven to have anti-carcinogenic activity in several tissues, although high doses of β-carotene failed to exhibit chemopreventive activity in clinical trials. In this review, cancer prevention using carotenoids are reviewed and the possible mechanisms of action are described.     

Status of methodology for the determination of fat-soluble vitamins in foods, dietary supplements, and vitamin premixes

Fat-soluble vitamins (FSVs) include vitamin A, carotenoids, vitamins D, E, and K. New legislation is being introduced in many countries to reinforce regulatory compliance of declared concentrations of vitamins and other micronutrients in food products and dietary supplements. The levels of FSVs are likely to be more closely scrutinized due to their potential health risks associated with overdosing, in particular of vitamin D. However, a proviso of stricter regulatory compliance is that analytical methods must be fit-for-purpose, providing adequate accuracy and precision. Official methods have been published by organizations such as AOAC INTERNATIONAL, European Committee for Standardization, International Dairy Federation, U.S. Pharmacopeia, and International Organization for Standardization. The methods available for foods, dietary supplements, and vitamin premixes are evaluated in this review. In general, these methods show adequate precision for regulatory compliance; however, the field of application has not often been evaluated for a sufficiently large range of food matrixes. Gaps have been noted in the range of published official procedures, particularly for carotenoids and vitamin premixes. The potential of some recent developments in sample preparation and chromatographic techniques were evaluated to provide improved procedures for FSV analysis the future.     

Latest Insights on Novel Deep Eutectic Solvents (DES) for Sustainable Extraction of Phenolic Compounds from Natural Sources

Phenolic compounds have long been of great importance in the pharmaceutical, food, and cosmetic industries. Unfortunately, conventional extraction procedures have a high cost and are time consuming, and the solvents used can represent a safety risk for operators, consumers, and the environment. Deep eutectic solvents (DESs) are green alternatives for extraction processes, given their low or non-toxicity, biodegradability, and reusability. This review discusses the latest research (in the last two years) employing DESs for phenolic extraction, solvent components, extraction yields, extraction method characteristics, and reviewing the phenolic sources (natural products, by-products, wastes, etc.). This work also analyzes and discusses the most relevant DES-based studies for phenolic extraction from natural sources, their extraction strategies using DESs, their molecular mechanisms, and potential applications.     

Synthesis of heterocyclic compounds via Michael and Hantzsch reactions

Heterocycles represent the largest diversity of organic compounds with signifcant chemical, biomedical, and industrial applications. They exist in numerous natural products, dyes, and as scaffolds in diverse drugs and related pharmaceutically active substances. Substantial attention has been paid to develop various elegant methods to synthesize heterocycles. Among different strategies, Michael and Hantzsch reactions are considered as effective approaches for construction of heterocycles and their corresponding fused derivatives. This review covers this area especially in the last 10 years. The heterocyclic systems reported in this review are classified according to the kind of the heterocyclic systems.     

Characterization of natural organic colorants in historical and art objects by high‐performance liquid chromatography

High‐performance liquid chromatography plays an important role in analysis of historical organic colorants. A number of papers have been published in this field over the last 30 years. Classification of the most commonly used natural dyes and an overview of high‐performance liquid chromatography methods with main focus on recent works (2008 to the beginning of 2014) are provided. The review deals with an entire analytical protocol covering sample preparation, chromatographic separation, and suitable detection (UV/visible and fluorescent spectroscopy and mass spectrometric techniques). High‐performance liquid chromatography has been successfully used in the complete characterization of some organic dyestuffs present in historical and art objects. The possibilities and difficulties for identification of natural sources of historical colorants are also discussed.     

The Identification of Cotton Fibers Dyed with Reactive Dyes for Forensic Purposes

Some of the most common microtraces that are currently collected at crime scenes are fragments of single fibers. The perpetrator leaves them at a crime scene or takes them away, for example, on their clothing or body. In turn, the microscopic dimensions of such traces mean that the perpetrator does not notice them and therefore usually does not take action to remove them. Cotton and polyester fibers dyed by reactive and dispersion dyes, respectively, are very popular within clothing products, and they are hidden among microtraces at the scene of a crime. In our recently published review paper, we summarized the possibilities for the identification of disperse dyes of polyester fibers for forensic purposes. In this review, we are concerned with cotton fibers dyed with reactive dyes. Cotton fibers are natural ones that cannot easily be distinguished on the basis of morphological features. Consequently, their color and consequently the dye composition are often their only characteristics. The presented methods for the identification of reactive dyes could be very interesting not only for forensic laboratories, but also for scientists working in food, cosmetics or pharmaceutical/medical sciences.     

Covalent Triazine Frameworks(CTFs) for Photocatalytic Applications

Covalent triazine frameworks(CTFs) as a new type of porous organic polymers(POPs) with nitrogen-rich content, high chemical stability, visible light sensitive, metal-free and fully conjugated structure, have gained considerable attention in the last ten years owing to their great potential in extensive applications, especially for photocatalysis systems. In this review, we propose to provide current progress in the design and synthesis of CTFs, along with an emphasis on their photocatalytic applications. Firstly, a brief background including the development of photocatalytic areas is provided. Then, synthetic strategies of CTFs are described and compared. Furthermore, the evolution of CTF materials in photocatalysis fields and strategies for enhancing photocatalytic performance is presented. Finally, some perspectives and challenges on synthesizing high crystalline CTFs and designing excellent catalytic performance of CTF materials are discussed, inspiring the development of CTF materials in photocatalytic applications.     

Cyanine Dyes Containing Quinoline Moieties: History,Synthesis, Optical Properties,and Applications

Cyanine dyes carrying quinoline moieties are an important class of organic molecules that are of great interest for applications in many fields like medicine, pharmacology, and engineering. Despite their exceptional properties, such as stability, high molar extinction coefficients, and high pH-sensitivity, this class of dyes has been less analyzed and reviewed in the last few decades. Therefore, this review article focuses on discussing the history of quinoline compounds, various synthetic routes to prepare quinolinium salts and symmetrical and asymmetrical mono-, di-, tri-, penta- and heptamethine cyanine dyes, containing quinoline moieties, together with their optical properties and applications as photosensitizers in photodynamic therapy, probes in biomolecules for labeling of nucleic acids, as well as imaging agents.     

Stir-bar sorptive extraction: A view on method optimisation,novel applications,limitations and potential solutions

Introduced in 1999 as a novel solventless sample preparation method, stir-bar sorptive extraction (SBSE) has become a popular analytical technique for the pre-concentration of organic compounds into a polydimethylsiloxane (PDMS)-coated stir-bar. In the last 10 years, hundreds of applications in the environmental, food and biomedical fields can be found in the literature. However, only PDMS-coated stir-bars are commercially available, which reduces the applicability of SBSE to the extraction of the non-polar compounds due to the poor extractability of more polar analytes. In this review, a view on method optimisation, limitations, potential solutions such as in-house coatings and derivatisation and novel applications in multi-residue analysis and passive sampling are revised.     

Anthocyanins Recovered from Agri-Food By-Products Using Innovative Processes: Trends,Challenges, and Perspectives for Their Application in Food Systems

Anthocyanins are naturally occurring phytochemicals that have attracted growing interest from consumers and the food industry due to their multiple biological properties and technological applications. Nevertheless, conventional extraction techniques based on thermal technologies can compromise both the recovery and stability of anthocyanins, reducing their global yield and/or limiting their application in food systems. The current review provides an overview of the main innovative processes (e.g., pulsed electric field, microwave, and ultrasound) used to recover anthocyanins from agri-food waste/by-products and the mechanisms involved in anthocyanin extraction and their impacts on the stability of these compounds. Moreover, trends and perspectives of anthocyanins’ applications in food systems, such as antioxidants, natural colorants, preservatives, and active and smart packaging components, are addressed. Challenges behind anthocyanin implementation in food systems are displayed and potential solutions to overcome these drawbacks are proposed.     

Occurrence and Determination of Carotenoids and Polyphenols in Different Paprika Powders from Organic and Conventional Production

Paprika powder is a good source of different carotenoids and polyphenols, which play a key role in preventing certain diseases (some kinds of cancer and cardiovascular diseases). They can also be used as natural food colorants. Organic production is characterized by strict rules, but products obtained in this way contain more bioactive compounds, such as carotenoids and polyphenols. The aim of this study was to measure and identify carotenoids and polyphenols in different paprika samples (sweet, hot, smoked, and chili) obtained by organic and conventional production. Quantitative and qualitative carotenoid and polyphenols analysis showed that the experimental samples contained different concentrations of these compounds.     

Determination of additives and organic contaminants in food by CE and CEC

The application of CE to the analysis of additives and organic contaminants in food since 2001 has been reviewed. Additives included in the review are dyes, preservatives, antioxidants and sweeteners. Organic contaminants included in the review are pesticides, antibiotics and those produced during processing or cooking food. The review highlights the strategies and approaches adopted in making CE suitable for the determination of analytes at residue level and in complicated matrices.     

分子印迹聚合物在极性农药残留检测中的应用进展

极性农药包括杀菌剂、除草剂、杀虫剂等,种类丰富,成本低廉,在农业中应用广泛,其滥用易导致水资源和土壤等环境污染,人类通过间接接触动植物源性食品和环境中的极性农药残留也增加了农药暴露风险。极性农药的物理化学性质差异大,通常痕量存在于食品和环境样品等复杂基质中,这对其准确检测分析带来了挑战。分子印迹聚合物(MIPs)作为一种人工制备的选择性吸附剂,具有与模板分子在空间结构、大小尺寸和功能基团上互补的特定识别位点,且易于制备,成本低,稳定性好,重复利用率高,已被广泛用于极性农药残留的样品前处理和分析检测中。MIPs可以作为固相萃取(SPE)、固相微萃取(SPME)、磁性固相萃取(MSPE)、搅拌棒固相萃取(SBSE)等前处理方法的吸附剂,还可用于制备光、电、化学传感器,作为质谱检测的离子源基底和拉曼光谱的增强基底。目前针对极性农药残留的检测,已有许多研究报道了多种分子印迹材料用于高效分离分析各种复杂基质中的极性农药残留,但未见此方面的综述报道。该文首先介绍了MIPs的印迹策略、聚合策略,并针对传统MIPs制备和应用中存在的问题,简要概括了一些新型的分子印迹策略和制备技术;然后从极性农药残留分析的角度出发,总结归纳了分子印迹材料近年来特别是近5年来在各种极性农药残留(包括新烟碱类、有机磷类、三嗪类、唑类、脲类等)检测中的应用,并针对现存问题展望了其未来的发展方向和趋势。     

Hydrophilic carotenoids: recent progress

Carotenoids are substantially hydrophobic antioxidants. Hydrophobicity is this context is rather a disadvantage, because their utilization in medicine as antioxidants or in food chemistry as colorants would require some water dispersibility for their effective uptake or use in many other ways. In the past 15 years several attempts were made to synthetize partially hydrophilic carotenoids. This review compiles the recently synthetized hydrophilic carotenoid derivatives.     

Recent advances in phenothiazine-based dyes for dye-sensitized solar cells

Dye-sensitized solar cells(DSSCs) have attracted significant attention as alternatives to conventional silicon-based solar cells owing to their low-cost production,facile fabrication,excellent stability and high power conversion efficiency(PCE).The dye molecule is one of the key components in DSSCs since it significant influence on the PCE,charge separation,light-harvesting,as well as the device stability.Among various dyes,easily tunable phenothiazine-based dyes hold a large proportion and achieve impressive photovoltaic performances.This class of dyes not only has superiorly non-planar butterfly structure but also possesses excellent electron donating ability and large π conjugated system.This review summarized recent developments in the phenothiazine dyes,including small molecule phenothiazine dyes,polymer phenothiazine dyes and phenothiazine dyes for co-sensitization,especially focused on the developments and design concepts of small molecule phenothiazine dyes,as well as the correlation between molecular structures and the photovoltaic performances.     

Cytometric methods for measuring bacteria in water: advantages, pitfalls and applications

Rapid detection of microbial cells is a challenge in microbiology, particularly when complex indigenous communities or subpopulations varying in viability, activity and physiological state are investigated. Flow cytometry (FCM) has developed during the last 30 years into a multidisciplinary technique for analysing bacteria. When used correctly, FCM can provide a broad range of information at the single-cell level, including (but not limited to) total counts, size measurements, nucleic acid content, cell viability and activity, and detection of specific bacterial groups or species. The main advantage of FCM is that it is fast and easy to perform. It is a robust technique, which is adaptable to different types of samples and methods, and has much potential for automation. Hence, numerous FCM applications have emerged in industrial biotechnology, food and pharmaceutical quality control, routine monitoring of drinking water and wastewater systems, and microbial ecological research in soils and natural aquatic habitats. This review focuses on the information that can be gained from the analysis of bacteria in water, highlighting some of the main advantages, pitfalls and applications.