Enzymatic Transformations Involved in the Biosynthesis of Microbial Exo‐polysaccharides Based on the Assembly of Repeat Units

Microbial exo‐polysaccharides can serve as valuable biopolymers in medicine, food and the feed industry as well as in various technical applications as substitutes of petro‐based polymers or with unusual performance. Due to their different natural functions, they have vastly diverse structures, which lead to a very different properties. This structural diversity is brought about by complex biosyntheses based on enzymes whose genes are mostly encoded in clusters within the genomes of the different microbial species. The organisation of the genes and the chemical structures of the corresponding polysaccharides are closely related. Here, we will mainly focus on the genetics and biosynthesis of some major bacterial hetero‐polysaccharides that are based on repeat unit assembly and will present specific examples of enzymatic transformation steps. Finally, a short outlook will be given on how in vivo modifications based on enzymatic transformations could be used to engineer these polymers.     

Spray-Drying Microencapsulation of Anthocyanins by Natural Biopolymers: A Review

There has been an increased interest in the development of food colorants from natural sources as alternatives to synthetic dyes because of both legislative actions and consumer concerns. Anthocyanins are of great interest for the food industry since they give a wide range of colors as well as nutraceutical activities. Nevertheless, due to their low stability to environmental conditions during processing and storage, introducing those compounds into foods is challenging. Microencapsulation may be an efficient way to introduce such compounds into those products. An important step in developing microcapsules is the selection of a biopolymer (wall material) which meets the required criteria. Hence, this review will focus on microencapsulation of anthocyanins with different biopolymers through spray drying to develop natural colorant pigments which possess high stability, solubility, and dispersibility. Our goal is to give updated information regarding microencapsulation of anthocyanins by spray drying, as well as its effectiveness, developments, and optimized conditions which will be discussed.     

Polyhydroxyalkanoates: Recent Advances in Their Synthesis and Applications

Polyhydroxyalkanoates (PHAs) are microbial biopolymers (polyesters) that have a wide range of functions and applications. They serve in nature mainly as carbon and energy storage materials for a variety of microorganisms. In past decades, their utilization has attracted much attention, from commodities and degradable plastics to specialty performance materials in medicine. PHA biosynthesis has been well understood, and it is now possible to design bacterial strands to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are very manifold: some are derived from food‐based carbon sources (e.g., fats and oils (triglycerids)), thus raising concerns with regard to the sustainability of their productions in terms of crop area and food. In addition, hemicellulose hydrolysates, crude glycerol, and methanol are very promising carbon sources for the sustainable production of PHAs. The integration of PHA production within a modern biorefinery is an important issue and can result in a simultaneous production of biofuels and bioplastics. Furthermore, many chemical‐synthetic procedures by means of efficient catalysts can give access to a variety of PHAs. This article summarizes recent developments in these fields and emphasizes the importance of a sustainable PHA‐based industry. Practical Applications: Practical applications of the microbial polyesters PHAs are, for example, a variety of sustainably produced commodities as well as special applications in (bio)medicine, for example, tissue engineering.     

Industrial application of microbial lipases: A review

Commercial microbial lipases have been used in dairy and other food processes, and lipases produced in situ by microorganisms are important in making foods palatable and acceptable. Microbial lipases have been used in detergents, pharmaceuticals, cosmetics, leather processing, production of aliphatic acids, and in the treatment of domestic and industrial wastes. Manufacturers offer lipolytic enzymes in powder form free of other enzymes, and sometimes they are microencapsulated for specialized applications.     

药用植物内生真菌多糖研究进展

真菌多糖具有多种生理活性,广泛应用于医药、农业、食品等行业。基于植物内生真菌生长过程中会产生与宿主相同或相似的生理活性成分,药用植物生理活性的多样性赋予了其内生真菌活性的多样性,药用植物内生真菌是开发新型天然活性多糖的资源宝库。综述了近些年来关于药用植物内生真菌作为诱导子调节植物生长、代谢及其体外抗氧化、抗肿瘤、抑菌、降血糖等多种生理作用的研究进展。并对今后的研究方向进行展望,以期为药用植物内生真菌多糖的开发利用提供参考。     

新型功能性低聚糖的生产与研究

综述了功能性低聚糖的生产制备方法及各自的特点。功能性低聚糖因具有独特的生理功能,是目前食品工业研究开发的热点。迄今为止,制备途径主要可分为以下４种：（１）由天然植物中提取;（２）糖基转移,包括化学转移和酶转移;（３）聚合法,包括化学聚合与酶聚合;（４）多糖降解,包括化学降解和酶法降解。     

Measuring protein quality

An alternative to the time-consuming and expensive PER assay for measuring food protein quality is needed by the food industry. Many biological and chemical-based assays for measuring protein quality have been described in the literature. Most of these are still too complicated, time-consuming, or too narrow in the range of foods they will test for daily quality control use. In the past five years, rapid methods have been developed that employ chemical assays for essential amino acid composition and availability or biological assays that measure protein digestibility and growth on food proteins. Most of these assays can be completed in five days or less and are applicable to a broad range of foods. These developments have brightened the prospects for the eventual development of a rapid assay that the food industry routinely can use to monitor protein quality. This paper has discussed two assays that were tested with a wide variety of foods and that take less than 72 hr to complete. The C-PER assay, uses data on the in vitro protein digestibility and EAA composition of a food protein to predict its protein quality in terms of PER. The C-PER technique is not limited by the protein, fat, additive or spice levels in the food to be tested, and is therefore applicable to a wide range of food ingredients and processed foods. The second assay is based on the growth of the protozoanTetrahymena thermophila WH₁₄ on a proteolytic enzyme hydrolyzed food sample along with in vitro protein digestibility data to predict protein quality in terms of T-PER. Because theTetrahymena are more difficult to control on a day to day basis, the error of the T-PER estimate is greater than that for the C-PER estimate. Also, sinceTetrahymena growth is greatly affected by various food additives and spices, caution should be used when this assay is used to measure protein quality in foods where the composition is not definitely known. The T-PER assay is best suited for assaying protein quality in protein-containing food ingredients, such as meats, flours, protein concentrates and isolates, or on foods where the exact composition is known.     

Biopolymer-based functional composites for medical applications

Over the last decade, numerous biopolymers have received more attention in medical applications involving novel biomaterials because of their biocompatibility, biodegradability, and ease of processing. To date, many biopolymer-based functional composites have been developed to increase the value of raw biopolymers obtained from natural sources or microbial systems. This review article covers general information on various biopolymers, important methods for biopolymer-based composites preparation including their advantages and disadvantages, and surface topography for tissue engineering. In addition, this article provides comprehensive knowledge and highlights recent research on functional biopolymer composites used in various medical applications, such as tissue engineering comprising skin, bone, cartilage, vascular graft, and other organs, implantable medical devices including stent and barrier membrane, and some delivery systems of bioactive agents. Furthermore, the article presents a brief overview on several challenges and future scope in this field.     

褐藻多糖硫酸酯的生物活性及应用前景

褐藻多糖硫酸酯是褐藻的重要活性成分,可用于药品、保健品、食品和化妆品等领域。介绍了近年来褐藻多糖硫酸酯的生物活性研究进展,详细讨论了其抗凝血、抗肿瘤、免疫调节、抗炎等作用和工业应用前景。     

生物高聚物玻璃化转变温度计算

目前玻璃化转变温度一般都通过实验获得．但是同一样品采取不同方法,结果有较大差别。采用传统测量方法,既浪费时间又很繁琐,并且测量仪器昂贵。应用基因贡献法计算生物高聚物及共混、共聚的玻璃化转变温度,计算结果与实验值吻合较好。介绍塑性方程如Gordon-Taylor和Couchman-Karasz方程。这些信息有利于食品科学研究及冷冻食品加工和储藏。     

Freshwater Plants Synthesize Sulfated Polysaccharides: Heterogalactans from Water Hyacinth (Eicchornia crassipes)

Sulfated polysaccharides (SP) are found mainly in seaweeds and animals. To date, they have only been found in six plants and all inhabit saline environments. Furthermore, there are no reports of SP in freshwater or terrestrial plants. As such, this study investigated the presence of SP in freshwaters Eichhornia crassipes, Egeria densa, Egeria naja, Cabomba caroliniana, Hydrocotyle bonariensis and Nymphaea ampla. Chemical analysis identified sulfate in N. ampla, H. bonariensis and, more specifically, E. crassipes. In addition, chemical analysis, FT-IR spectroscopy, histological analysis, scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDXA), as well as agarose gel electrophoresis detected SP in all parts of E. crassipes, primarily in the root (epidermis and vascular bundle). Galactose, glucose and arabinose are the main monosaccharides found in the sulfated polysaccharides from E. crassipes. In activated partial thromboplastin time (APTT) test, to evaluate the intrinsic coagulation pathway, SP from the root and rhizome prolonged the coagulation time to double the baseline value, with 0.1 mg/mL and 0.15 mg/mL, respectively. However, SP from the leaf and petiole showed no anticoagulant activity. Eichornia SP demonstrated promising anticoagulant potential and have been selected for further studies on bioguided fractionation; isolation and characterization of pure polysaccharides from this species. Additionally in vivo experiments are needed and are already underway.     

Nutritional contribution of soy protein to food systems

From the nutritional point of view, soybeans can play a significant role in at least three aspects: as a source of supplementary and complementary protein, as a source of calories, and as a source of nitrogen. The protein role is probably the most important for food systems of developed and underdeveloped populations, while the role as a source of protein and calories applies more to food systems of developing populations. Soy protein efficiently supplements cereal grain protein, because it corrects the lysine deficiency of cereals. In some cases, for example with maize, it also corrects the tryptophan deficiency. On the other hand, the essential amino acid pattern of soybean protein complements that of other protein sources, for example cereal grains, cottonseed flour, and, in general, lysine deficient protein sources. This makes feasible the preparation of foods of optimum protein quality and of a high protein content. Because of its quality, soybean protein can replace animal protein without a significant decrease in nutritive value, for example as milk and meat extender; for diets low in quantity and quality of protein and deficient in calories, soybeans, as full-fat flour, provide both. Because of cultural eating habits, it is difficult to conceive the use of soybeans as complete substitutes of common beans; therefore, efforts should be made to use soy protein in combination with common foods used by populations to whom soybeans are foreign food. Examples of the nutritional benefits derived from the use of soybean protein as flour or protein concentrate or as full-fat soybean flour are given, particularly for foods consumed in Latin American countries. Besides the role soybeans play in human foods, they also play a significant role in the animal industry as a very important component of diets. The efficiency of the swine and poultry industry would be lower if it were not for the nutritional contribution of soybeans.     

Biobased adhesives,gums, emulsions,and binders: current trends and future prospects

Biopolymers derived from renewable resources are an emerging class of advanced materials that offer many useful properties for a wide range of food and nonfood applications. Current state of the art in research and development of renewable polymers as adhesives, gums, binders, and emulsions is the subject of this review. Much of the focus will be on major biopolymers such as starch, proteins, lignin, oils, and their derivatives found in both natural and modified forms, but other biopolymers of promising commercial interest will also be included where warranted. Polymers produced in nature are remarkably diverse in their chemistry, thermomechanical properties, rheology, plasticity, and chemical reactivity. In particular, their capacity to undergo a wide array of chemical modifications yields materials with tailored properties suitable for use as adhesives, gums, coatings, emulsions, and binders. Many such materials are now widely used in commercial products like building materials, lubricants, sealants, coatings, bonding aids, pharmaceuticals, paper, glues, flocculants, processed and frozen foods, as well as tissue engineering and bone repair products. This review provides a general overview of biobased polymers highlighting their source, availability, properties, and usage in industrial products along with the future prospects, challenges, and opportunities they offer.     

Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.     

Thermochemical Characterization of Eight Seaweed Species and Evaluation of Their Potential Use as an Alternative for Biofuel Production and Source of Bioactive Compounds

Algae are underexplored resources in Western countries and novel approaches are needed to boost their industrial exploitation. In this work, eight edible seaweeds were subjected to their valorization in terms of nutritional characterization, thermochemical properties, and bioactive profile. Our results suggest that seaweeds present a rich nutritional profile, in which carbohydrates are present in high proportions, followed by a moderate protein composition and a valuable content of ω-3 polyunsaturated fatty acids. The thermochemical characterization of seaweeds showed that some macroalgae present a low ash content and high volatile matter and carbon fixation rates, being promising sources for alternative biofuel production. The bioactive profile of seaweeds was obtained from their phenolic and carotenoid content, together with the evaluation of their associated bioactivities. Among all the species analyzed, Porphyra purpurea presented a balanced composition in terms of carbohydrates and proteins and the best thermochemical profile. This species also showed moderate anti-inflammatory activity. Additionally, Himanthalia elongata extracts showed the highest contents of total phenolics and a moderate carotenoid content, which led to the highest rates of antioxidant activity. Overall, these results suggest that seaweeds can be used as food or functional ingredient to increase the nutritional quality of food formulations.     

Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.     

Kinetics of Adhesion Staphylococcus aureus on Glass in the Presence of Sodium Lauryl Sulfate

Bacterial contamination of surfaces is a natural and spontaneous process that often results in the formation of biofilms. The extracellular matrix of biofilm is mostly composed of proteins, polysaccharides, and extracellular DNA and is responsible for the strong persistent ability of biofilm in the food industry. Despite cleaning and disinfection processes, persistent bacteria cause a major problem in food processing environments. Synthetic surfactants, mainly anionic surface-active agent, are commonly used as detergents, foaming agents, wetting agents, emulsifiers, and dispersants. Their tendency to adsorb to surfaces and interfaces and modify their surface tension, is considered among their main properties. They also have the ability to attach to bioactive macromolecules such as proteins, peptides, and DNA causing cell membrane damage. In order to estimate the adhesion kinetic and proliferation of pathogenic bacteria Staphylococcus aureus, the surface of glass was coated with anionic surfactant Sodium Lauryl Sulfate (SLS). Moreover, SLS was added in suspension with the culture medium. The physicochemical properties of the material were calculated using the contact angle measurement method and bacterial hydrophobicity using the microbial adhesion to hydrocarbons (MATH) test. The obtained results showed that the number of adhering cells increased gradually as a function of time. However, changing the surface properties of the glass and S. aureus has affected the rate of adherent cells with time as well as their organization. SLS inhibited the attachment of cells, whether it is added with the microbial suspension or at the surface of the support. Generally, the present article points to a relationship between the microbial adhesion, the surface chemistry of the solid material and the bacteria, and the suspension properties.     

1,3-二羟基丙酮的合成与应用研究进展

1,3-二羟基丙酮作为重要的化工医药中间体,广泛应用于化工、医药、化妆品和食品领域。主要综述了1,3-二羟基丙酮的合成方法,包括化学合成法和微生物合成法,并介绍了其在化工与医药领域的最新应用进展。     

海藻生物活性物质应用研究进展

海藻中生物活性物质可应用于医药、功能食品、食品添加剂、生态保护、动物饲料等诸多领域。本文介绍了海藻中生物活性物质的种类,包括多糖类、蛋白类、萜类、甾醇类、多酚类、环状多硫化合物、大环内酯类等,综述了这些活性物质在药品、食品、工业及农业上的应用。指出国内在生物质活性物质在医药及工业上的应用有很大潜力,目前应注重对海藻中生物活性物质的提取方法研究,并对其生物结构、生物活性、作用机理等进行分析探讨。     

Characterization and applications of a new composite material obtained by green synthesis,through deposition of zinc oxide onto calcium carbonate precipitated in green seaweeds extract

Zinc oxide was deposited onto calcium carbonate precipitated using a template of polysaccharides from Ulva lactuca green seaweeds (Black Sea). The resulted composite material was characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, UV–vis and FTIR spectroscopy. The therapeutic effect of prepared composite material was assessed in vivo as a topical application for the burns treatment and compared with that of ZnO. An increased antioxidant activity by combining zinc oxide with calcium carbonate capped with polysaccharides from green seaweeds extract in a composite material was demonstrated.