玉米醇溶蛋白基纳米颗粒的制备及应用研究进展

玉米醇溶蛋白是玉米中的主要储藏蛋白,是天然的两亲性高分子材料,因其具有自主装特性及在不同溶液中呈现不同的溶解特性,可通过多种方式构建成纳米颗粒,进而对生物活性物质进行荷载和输送,或用来稳定乳液。近年来,玉米醇溶蛋白基纳米颗粒在食品和营养物质运输领域的研究不断深入。研究发现,利用玉米醇溶蛋白与蛋白质、多糖、多酚、表面活性剂等物质进行复合,可以得到更加稳定且对生物活性物质包埋率、荷载量更高的玉米醇溶蛋白基纳米颗粒。本文对玉米醇溶蛋白基纳米颗粒的制备方法与种类、应用情况和目前存在的问题进行了综述,为玉米醇溶蛋白在食品领域的实际应用提供理论参考。     

Zein molecules in aqueous acetic acid solution: Self-assembling behaviors and formation mechanism of gluten-free doughs

The assembly behavior of biopolymers is affected by the type of solvent used. Previous investigations have focused on the self-assembly of zein molecules in aqueous ethanol. In this study, the self-assembly behavior of zein molecules in aqueous acetic acid solutions and their application in the development of zein-based gluten-free doughs was investigated. Zein molecules in low concentrations of acetic acid (30%–60%, v/v) assembled into irregular entities, in medium concentrations (70%, v/v) there was intermediate transition, and at high concentrations (80%–100%, v/v) they formed regular spheres. Interestingly, protein fibril formation was found to occur in 50% zein solutions in 50% and 60% acetic acid, as self-standing gels with solid-like properties resulted and the findings were verified using rheology. The 50% zein solutions in 70% acetic acid could form viscoelastic masses after anti-precipitation with the addition of excess water. Gluten-free dough with wheat-like properties was obtained by mixing the viscoelastic zein masses with wheat starch at room temperature. SEM observations showed that the formation mechanism for zein-based doughs involves the dispersion of starch granules in a three-dimensional zein network. These results will help to improve our understanding of zein assembly behavior regulation, and provide technical support for the development of zein in gluten-free food products.     

乳酸对玉米醇溶蛋白基面团品质提升的作用

以玉米醇溶蛋白、玉米淀粉、沙蒿胶为原料制备玉米醇溶蛋白基无麸质面团（简称Z面团）,以玉米淀粉和沙蒿胶所制面团（简称NZ面团）为对照。通过调控面团中乳酸含量（L）和原料粉含量（F）的比例（简写为L/F,mL/g）,比较乳酸含量对Z面团与NZ面团粉质性能的影响规律,表明玉米醇溶蛋白是影响Z面团粉质性能的关键组分。面团中L/F为2∶50的Z面团（Z2）稳定时间最长,弱化度最低,粉质质量指数最高,加工品质良好。探究在乳酸调节下,Z面团中玉米醇溶蛋白的理化性质与结构变化,发现乳酸会引起玉米醇溶蛋白的脱酰胺反应和蛋白质水解,促进α-玉米醇溶蛋白二倍体向单倍体转变,改变玉米醇溶蛋白的表面疏水性和二级结构组成。基于以上研究,将Z面团制为面条,考察乳酸含量对玉米醇溶蛋白基面条蒸煮品质的影响,其中Z2面条不易断条,蒸煮损失最少,质地良好。综上,适量的乳酸可改善玉米醇溶蛋白基无麸质面团粉质性能,提高玉米醇溶蛋白的表面疏水性,增加β-折叠占比,优化玉米醇溶蛋白基面条蒸煮品质。     

乳酸调控玉米醇溶蛋白基面团流变特性和微观结构的研究

改善无麸质谷物食品品质一直是科学家关注的热点。本研究以玉米醇溶蛋白、玉米淀粉、沙蒿胶为原料,制备玉米醇溶蛋白基无麸质面团。采用两种乳酸引入方式,通过调节面团中乳酸和玉米醇溶蛋白的比例（L/Z比）,探究乳酸对玉米醇溶蛋白基无麸质面团的流变性质和面团中玉米醇溶蛋白微观结构的影响规律。结果表明:面团中L/Z比的增加,会导致乳酸添加组（T面团）和乳酸预处理玉米醇溶蛋白组面团（C面团）的储能模量（G′）下降,损耗系数（tanδ）逐渐上升。乳酸引入方式的不同,会导致面团的流变性能存在差异。当L/Z比一定时,T面团的G′低于C面团,tanδ高于C面团。随面团中L/Z比增加,T面团的拉伸性能呈先上升后下降趋势,当L/Z比从0:10增加到2:10时（T0~T2）,T面团的拉伸性逐渐提高,面团中玉米醇溶蛋白团块状聚集减少,逐渐联结成网;T2拉伸性能最佳,面团中玉米醇溶蛋白网络质地均一,具备应用潜力;T3~T5时,面团的拉伸性逐渐下降,面团中玉米醇溶蛋白网络变弱,对淀粉颗粒包裹水平下降。C面团拉伸性较差,无法有效进行相关实验,可能与面团中未能构建起结实而连贯的蛋白质网络有关。     

Multifunctional nanocellulose/metal and metal oxide nanoparticle hybrid nanomaterials

Abstract

Nanocellulose materials are derived from cellulose, the most abundant biopolymer on the earth. Nanocellulose have been extensively used in the field of food packaging materials, wastewater treatment, drug delivery, tissue engineering, hydrogels, aerogels, sensors, pharmaceuticals, and electronic sectors due to their unique chemical structure and excellent mechanical properties. On the other hand, metal and metal oxide nanoparticles (NP) such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP have a variety of functional properties such as UV-barrier, antimicrobial, and magnetic properties. Recently, nanocelluloses materials have been used as a green template for producing metal or metal oxide nanoparticles. As a result, multifunctional nanocellulose/metal or metal oxide hybrid nanomaterials with high antibacterial properties, ultraviolet barrier properties, and mechanical properties were prepared. This review emphasized recent information on the synthesis, properties, and potential applications of multifunctional nanocellulose-based hybrid nanomaterials with metal or metal oxides such as Ag NP, ZnO NP, CuO NP, and Fe₃O₄ NP. The nanocellulose-based hybrid nanomaterials have huge potential applications in the area of food packaging, biopharmaceuticals, biomedical, and cosmetics.     

Use of quantum nanodot crystals as imaging probes for cereal proteins

Quantum dots (QDs) also known as fluorescent semiconductor nanocrystals have unique optical and chemical properties. Their properties make them excellent fluorescent probes for biological applications which enable long term high quality imaging with the ability to conjugate to multiple biological targets. There are many applications of QDs in the biomedical field; however no applications exist in imaging of food structures. In this paper a detailed protocol for the use of QDs in imaging of gluten network in flat bread and zein in corn extrudates by combining covalent bioconjugation principles to the rules of immunohistochemistry is presented. In this study water soluble CdSe/ZnS core/shell quantum dots containing carboxyl terminated groups were used. The quantum dots had a wavelength of emission of 620 nm. Confocal laser scanning microscopy was used to observe the structure of cereal proteins tagged by QDs to visualize their location within the food matrix. Optical sections were collected within a sample size of 20 μm and processed with Zen 2009 image analysis software (Carl Zeiss MicroImaging GmbH) to obtain three dimensional images. Results showed that QDs can be covalently conjugated to both gluten and zein. They provide long term bright stable imaging capability for wheat gluten with very little quenching after multiple laser excitations overtime.     

Nanomaterials for products and application in agriculture,feed and food

BackgroundNanotechnology applications can be found in agricultural production, animal feed, food processing, food additives and food contact materials (hereinafter referred to as agri/feed/food). A great diversity of nanomaterials is reported to be currently used in various applications, while new nanomaterials and applications are reported to be in development.Scope and approachIt is expected that applications of nanomaterials in agri/feed/food will increase in the future and thereby increase the human and environmental exposure to such materials. To gain up-to-date knowledge we explored and reviewed the already marketed and in-development applications of nanomaterials in the agri/feed/food sectors upon the request of the European Food Safety Authority (EFSA). In this paper the results of the project are highlighted and discussed in more detail.Key findings and conclusionsThe majority of the applications of nanomaterials that we identified concerned application in food as food additives and food contact materials, while much fewer applications seem to be developed for agriculture and feed. Nano-encapsulates, silver, titanium dioxide and silica are the most often mentioned nanomaterials in the literature. About half of the identified applications are claimed to be already in use. In-development applications are found for nano-encapsulates and nano-composites in novel foods, food and feed additives, biocides, pesticides and food contact materials.     

Physicochemical Properties of Zein-Based Films by Electrophoretic Deposition Using Indium Tin Oxide Electrodes: Vertical and Horizontal Electric Fields

In this study, biodegradable and biocompatible zein films were prepared by electrophoretic deposition using indium tin oxide electrodes with two different modes: vertical and horizontal electric fields. The effects of the different mode of the electric field in the presence of ethanol on mechanical, hydrophobicity, water resistance properties, microstructures, and thermal stability of zein films were investigated. The results indicated that the physiochemical properties (tensile strength, hydrophobicity, water vapor permeability, water absorption, and thermal stability) of zein films prepared from the vertical electric field were superior to those of zein film produced from the horizontal electric field and the control. The results of scanning electron microscope demonstrated the presence of the compact and homogenous structures of zein films manufactured in electric fields. In summary, the knowledge achieved from this study could facilitate to prepare the zein-based films using a readily and scale-up method.     

Chemical composition,health effects,and uses of water caltrop

BackgroundWater caltrop (Trapa spp.) has been cultivated for food and traditional medicine in Asia for thousands of years. It is, however, considered as a pest in North America due to the adverse effects on ecological systems. Thus, a better understanding of the chemistry and potential applications of water caltrop may suggest strategies to utilize this aquatic plant.Scope and approachThis review summarizes the chemical composition, nutritional benefits, processing, and food and industrial uses of different parts of water caltrop from diverse species. The relationships between the components and potential uses of water caltrop are discussed.Key findings and conclusionsPeels and kernels of water caltrop are rich in starch, dietary fiber, essential amino acids, and certain types of phenolics and minerals, and showed a range of bioactivities such as anti-cancer and antioxidant capacities. Water caltrop has been utilized in diverse food and non-food sectors. There is great potential of water caltrop for various applications due to the unique chemical composition and abundance of supply.     

Microencapsulation of flax oil with zein using spray and freeze drying

Microencapsulation of flax oil was investigated using zein as the coating material. Central Composite Design - Face Centered was used to optimize the microencapsulation with respect to zein concentration (x₁) and flax oil concentration (x₂) using spray drying. Also, freeze drying was carried out at two zein:oil ratios. The quality of microcapsules was evaluated by determining encapsulation efficiency, flowing properties (Hausner ratio), and evaluating the morphology with scanning electron microscopy. The response surface model for microencapsulation efficiency showed a high coefficient of determination (R² = 0.992) and a non-significant lack of fit (p = 0.256). The maximum microencapsulation efficiencies were 93.26 ± 0.95 and 59.63 ± 0.36% for spray drying and freeze drying, respectively. However, microcapsules prepared by spray and freeze drying had very poor handling properties based on the Hausner ratio. The bulk density decreased with an increase in zein concentration at the same flax oil concentration. The morphology of the flax oil microcapsules depended on the zein:flax oil ratio and the process used for microencapsulation. Flax oil microcapsules prepared by spray drying appeared to be composed of heterogeneous spheres of various sizes at high zein:flax oil ratios. Microcapsules prepared by freeze drying resulted in agglomerated small spheres. These microcapsules might find a niche as functional food ingredients.     

The food matrix: implications in processing,nutrition and health

Abstract

The concept of food matrix has received much attention lately in reference to its effects on food processing, nutrition and health. However, the term matrix is used vaguely by food and nutrition scientists, often as synonymous of the food itself or its microstructure. This review analyses the concept of food matrix and proposes a classification for the major types of matrices found in foods. The food matrix may be viewed as a physical domain that contains and/or interacts with specific constituents of a food (e.g., a nutrient) providing functionalities and behaviors which are different from those exhibited by the components in isolation or a free state. The effect of the food matrix (FM-effect) is discussed in reference to food processing, oral processing and flavor perception, satiation and satiety, and digestion in the gastrointestinal tract. The FM-effect has also implications in nutrition, food allergies and food intolerances, and in the quality and relevance of results of analytical techniques. The role of the food matrix in the design of healthy foods is also discussed.     

Electrospun zein/PVA fibrous mats as three-dimensional surface for embryonic stem cell culture

This paper reports a new method of producing electrospun zein/polyvinyl alcohol (PVA) mats as three-dimensional (3D) cell culture surface material. The electrospun structure has many advantages and protein-based biomaterials possess unique properties preferred for cell biocompatibility. However, electrospun fiber matrices developed from proteins have poor mechanical properties and morphological stability in the aqueous environments required for cell culture. Efforts have been made to improve the properties of electrospun protein scaffolds, including dry mechanical for handling and surface hydrophilicity, but the current methods have major limitations, such as cytotoxicity and low efficiency. In this research, experimental data showed that the adding different proportion of PVA influenced the properties of the zein mats. Considering the properties of the mats and mouse embryonic stem cells growth behavior on the various electrospun mats, the EM3 (zein/PVA with mass ratios of 3:1) showed better growth status than any other mats. EM3 affixed to cover-glass could be autoclaved for 30?min at 120°C. In addition, embryonic stem cells cultured on chosen electrospun zein/PVA mats in vitro proved that culture products were easily attached onto mat and mat could be used for induction of stem cell differentiation and therefore promising mats for 3D cell culture surface applications.     

Contributions to advances in blend pellet products (BPP) research on molecular structure and molecular nutrition interaction by advanced synchrotron and globar molecular (Micro)spectroscopy

ABSTRACT

To date, advanced synchrotron-based and globar-sourced techniques are almost unknown to food and feed scientists. There has been little application of these advanced techniques to study blend pellet products at a molecular level. This article aims to provide recent research on advanced synchrotron and globar vibrational molecular spectroscopy contributions to advances in blend pellet products research on molecular structure and molecular nutrition interaction. How processing induced molecular structure changes in relation to nutrient availability and utilization of the blend pellet products. The study reviews Utilization of co-product components for blend pellet product in North America; Utilization and benefits of inclusion of pulse screenings; Utilization of additives in blend pellet products; Application of pellet processing in blend pellet products; Conventional evaluation techniques and methods for blend pellet products. The study focus on recent applications of cutting-edge vibrational molecular spectroscopy for molecular structure and molecular structure association with nutrient utilization in blend pellet products. The information described in this article gives better insight on how advanced molecular (micro)spectroscopy contributions to advances in blend pellet products research on molecular structure and molecular nutrition interaction.     

壳寡糖酶法糖基化修饰对玉米醇溶蛋白功能性质的影响

为了提高玉米醇溶蛋白的生物利用率,以微生物转谷氨酰胺酶为催化剂,壳寡糖(分子质量为1 500 Da)作为酰基受体,通过糖基化反应修饰玉米醇溶蛋白,分析糖基化修饰对玉米醇溶蛋白物化性质和抗氧化活性的影响。红外光谱和游离氨基含量的测定结果表明,在转谷氨酰胺酶的催化下,玉米醇溶蛋白与壳寡糖发生了共价结合。与玉米醇溶蛋白和交联玉米醇溶蛋白相比,糖基化玉米醇溶蛋白的表面疏水性显著降低,表明其水溶性显著改善;糖基化玉米醇溶蛋白的抗氧化活性(包括1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基、超氧阴离子自由基和羟自由基清除活性,还原力和亚铁离子螯合能力)显著提高,尤其是DPPH自由基清除活性,其EC50值为0.945 mg/m L;糖基化玉米醇溶蛋白的持水性、吸油性、乳化性和Zeta电位的绝对值均显著降低。实验结果可为糖基化玉米醇溶蛋白在食品工业的应用提供参考。     

Wettability, surface microstructure and mechanical properties of films based on phosphorus oxychloride-treated zein

BACKGROUND: Zein, the predominant protein in corn, has been extensively studied as an alternative packaging material in edible and biodegradable films. However, films made from 100% zein are brittle under normal conditions. The aim of this investigation was to improve the film‐forming properties of zein by chemical phosphorylation. The surface hydrophobicity, surface microstructure and mechanical properties of films based on untreated and phosphorus oxychloride (POCl₃)‐treated zein were evaluated and compared. The effect of POCl₃ treatment on the rheological properties of zein solutions was also studied. RESULTS: POCl₃ treatment, especially at pH 7 and 9, led to an increase in the apparent viscosity of zein solutions. Atomic force microscopy (AFM) analysis showed that the film based on POCl₃‐treated zein at pH 7 had a stone‐like surface microstructure with a higher roughness (R_q) than the untreated zein film. The AFM data may partially account for the phenomenon that this film exhibited high surface hydrophobicity (H₀). POCl₃ treatment diminished the tensile strength (TS) of zein films from 4.83–6.67 to 1.3–2.29 MPa. However, the elongation at break (EAB) of the films at pH 7 and 9 increased from 3.0–4.5% (control film) to 150.1–122.7% (POCl₃‐treated film), indicating the potential application of zein films in wrapping foods or in non‐food industries such as sugar, fruit or troche that need good extension packing materials. CONCLUSION: The data presented suggest that the properties of zein films could be modulated by chemical phosphorylation treatment with POCl₃ at an appropriate pH value. Copyright © 2011 Society of Chemical Industry     

Effect of Salt and Ethanol Addition on Zein–Starch Dough and Bread Quality

Development of viscoelastic doughs from non‐wheat proteins allows for a wider range of gluten‐free products. Little work has been completed to describe mechanisms of zein functionality in food systems. To identify factors responsible for dough development in zein–starch mixtures and their influence on zein bread quality, a mixture of 20% zein–80% maize starch was mixed with water and various reagents. Salts, NaSCN, NaCl, and Na₂SO₄ were evaluated at concentrations from 0 to 2M for their influence on the properties of zein–starch dough systems. NaSCN at low concentrations produced softer dough. Ethanol treatments produced softer more workable dough in the absence of salts. Increasing concentrations of NaCl and Na₂SO₄ resulted in coalescing of the proteins and no dough formation. The addition of β‐ME had minimal softening effects on zein–starch dough. Specific volumes of zein–starch bread increased with decreasing NaCl addition in bread formulations. Likewise, including 5% ethanol (v/v) in the bread formula increased bread quality.     

Buckwheat starch: Structures,properties, and applications

BackgroundThere is increasing interest in utilization of buckwheat for healthy food applications. Common buckwheat (Fagopyrum esculentum) and tartary buckwheat (Fagopyrum tataricum) are cultivated in Asia, Europe, and Americas for various food formulation and production. Starch, the major component of the seeds, may account over 70% of the dry weight. Therefore, it is expected that, to a large extent, the quality of starch determines the quality of buckwheat food products. Furthermore, Buckwheat starch has great potential for various food and non-food uses due to the unique structural and functional features.Scope and approachThis review summarises the current knowledge of chemical composition, chemical structure of amylose and amylopectin, physical structure of granules, physicochemical properties, enzyme susceptibility, modifications, and uses of buckwheat starch. Suggestions on how to better understand and utilise the starch are provided.Key findings and conclusionsAmylose contents of buckwheat starch ranged from 20 to 28%. Starch granules are most polygonal with size ranging from ∼2 to 15 μm and an average diameter of ∼6–7 μm. The polymorph is A-type. The amount of extra-long unit chains of amylopectin (DP > 100) is higher than that of cereal amylopectins. Low glycaemic index of buckwheat food products could be attributed to the non-starch components. Buckwheat starch has been used as fat replacer, ingredient for extruded products, nanocomposite material, and fermentation substrate for alcoholic beverage. It may be concluded that buckwheat starch can be a unique source of specialty starch for innovative food and non-food applications.     

Use of Electrospinning to Develop Antimicrobial Biodegradable Multilayer Systems: Encapsulation of Cinnamaldehyde and Their Physicochemical Characterization

In this work, three active bio-based multilayer structures, using a polyhydroxybutyrate-co-valerate film with a valerate content of 8 % (PHBV8) as support, were developed. To this end, a zein interlayer with or without cinnamaldehyde (CNMA) was directly electrospun onto one side of the PHBV8 film and the following systems were developed: (1) without an outer layer; (2) using a PHBV8 film as outer layer; and (3) using an alginate-based film as outer layer. These multilayer structures were characterized in terms of water vapour and oxygen permeabilities, transparency, intermolecular arrangement and thermal properties. The antimicrobial activity of the active bio-based multilayer systems and the release of CNMA in a food simulant were also evaluated. Results showed that the presence of different outer layers reduced the transport properties and transparency of the multilayer films. The active bio-based multilayer systems showed antibacterial activity against Listeria monocytogenes being the multilayer structure prepared with CNMA and PHBV outer layers (PHBV + zein/CNMA + PHBV) the one that showed the greater antibacterial activity. The release of CNMA depended on the multilayer structures, where both Fick’s and Case II transport—polymer relaxation explained the release of CNMA from the multilayer systems.Overall, the deposition of electrospun CNMA-loaded zein fibres on a PHBV8 layer is a promising methodology for the development of active bio-based multilayer systems, with a great potential for food packaging applications.     

PRESERVATION OF COMMERCIAL FISH BALL QUALITY WITH EDIBLE ANTIOXIDANT-INCORPORATED ZEIN COATINGS

Fish ball, a surimi product rich in lipid and protein, is a popular food in Taiwan. Because lipid oxidation is one of the major deterioration reactions for fish ball, the feasibility of preservation of fish ball quality by the application of antioxidant-incorporated zein coating was investigated. Three antioxidants including butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and n-propyl gallate (PG) were used to formulate the antioxidant zein coatings. Infrared spectroscopy was used to confirm the successful incorporation of antioxidant with zein protein; peroxide value ( POV ), thiobarbituric acid reactive substance (TBARS) and weight loss were used as the quality indicators of fish ball stored at 4C. While all three types of antioxidant-incorporated zein coatings significantly retarded the quality deterioration, PG-incorporated zein coating exerted better quality preservation effectiveness than BHA- and BHT-incorporated zein coatings.

PRACTICAL APPLICATIONS

Edible coatings have been under research for several decades. However, most of the studies are conducted for the investigations of physiochemical or mechanical properties and usually using simulated food systems. The lack of applications on the commercial food products manufactured from food plants makes the edible coatings somewhat unrealistic. Not prepared in a laboratory for academic purpose only, the fish ball used in the present study was a real commercial product. The promising results of antioxidant-incorporated zein coatings on commercial products presented in this report will enhance the confidence of food manufacturers on the edible coatings.     

QUALITY PRESERVATION OF COMMERCIAL FISH BALLS WITH ANTIMICROBIAL ZEIN COATINGS

ABSTRACT

To enhance the practical application of active edible coatings in the food industry, edible zein coatings incorporated with nisin (54.4 AU/cm²) or nisin/ethylenediaminetetraacetic acid (EDTA; 568 µg/cm²) were used to preserve the quality of commercially manufactured fish balls. The microbial load, total basic volatile nitrogen (TVB‐N) content and weight loss were served as quality indicators. The increase of microbial load of fish balls coated with antimicrobial zein during a 15‐day refrigeration storage period was less than 1 log cfu/g, while the microbial load increased about 3 log cfu/g for the control group without the coating treatment. The formation of TVB‐N was significantly (P < 0.05) reduced when fish balls were coated with antimicrobial zein. With or without antimicrobial agent, coated fish balls exerted significantly (P < 0.05) less weight loss than uncoated fish balls.

PRACTICAL APPLICATIONS

Although edible coatings or films containing bioactive substance have been intensively studied over the last few decades, most of these, still, have not had widespread commercial applications because the majority of studies were conducted with food‐simulated systems or food samples produced in laboratory. The fish balls commercially manufactured in a fishery product factory was used to demonstrate the efficacy of antimicrobial edible coating will enhance the confidence of food manufactures to apply the technology in their products.