Emulsion electrospinning: Fundamentals,food applications and prospects

BackgroundIn the past decades, many natural bioactive compounds with antioxidant, immunoregulatory, antimicrobial, and anticancer activities have been successfully identified in plant and animal materials. However, due to their poor solubility, unfavorable flavor, low bioavailability and instability during food processing and storage, the development of bioactive compounds used in the food industry presents many technological challenges.Scope and approachEmulsion electrospinning is a novel and simple technique to fabricate core-shell nanofibers, and either water-in-oil (W/O) or oil-in-water (O/W) emulsions can be electrospun to directly encapsulate hydrophilic or hydrophobic compounds into core-shell fibers, respectively. This review introduces fundamentals and advantages of emulsion electrospinning as well as its food applications. The effects of different types of emulsifiers on the formation of emulsion systems and emulsion-based electrospun fibers are highlighted. Further, the existing limitations and scope for future research are discussed.Key findings and conclusionsRecent studies have found that the emulsion-based electrospun nanofibers can enhance the encapsulation efficiency, stability, and bioavailability of bioactive compounds, as well as achieve targeted delivery and controlled release, thus providing new strategies to improve their barrier performance compared to conventional electrospinning and therefore facilitating the development of emulsion-based electrospun mats in the food industry.     

In vitro antioxidant activity and in vivo photoprotective effect of a red orange extract

Ultraviolet radiation causes damage to the skin, which may result in both precancerous and cancerous skinlesions and acceleration of skin ageing. Topical administration of enzymatic and non-enzymatic antioxidants is an effective strategy for protecting the skin against UV-mediated oxidative damage. Hence, a systematic study to evaluate the in vitro antioxidant activity and in vivo photoprotective effect of a standardized red orange extract (ROE) has been undertaken, where the main active ingredients are anthocyanins, hydroxycinnamic acids, flavanones and ascorbic acid. For the in vitro experiments, the ROE was tested in three models: (1) bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test); (2) peroxidation, induced by the water-soluble radical initiator 2,2'-azobis(2-amidinopropane) hydrochloride, of mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LUVs) (LP-LUV test); and (3) UV-induced peroxidation of phospatidylcholine multilamellar vesicles (UV-IP test). The in vivo antioxidant/radical scavenger activity was assessed by determining the ability of topically applied ROE to reduce UVB-induced skin erythema in healthy human volunteers. The results obtained in the DPPH, LP-LUV and UV-IP tests demonstrated the strong antioxidant properties of ROE, with a clear relationship between ROE scavenger efficiency and its content in antioxidant compounds. In particular, the findings obtained in the UV-IP test provide a strong rationale for using this extract as a photoprotective agent. During in vivo experiments, ROE provided to efficiently protect against photooxidative skin damage when topically applied immediately after skin exposure to UVB radiations. Interestingly, the protective effect of ROE appears higher than that elicited by another natural antioxidant (tocopherol) commonly employed in cosmetic formulations. In conclusion, the present findings demonstrate that ROE affords excellent skin photoprotection, which is very likely a result of the antioxidant/radical scavenger activity of its active ingredients. Thus, ROE might have interesting applications in both anti-photoageing and after-sun cosmetic products.     

静电纺丝技术在保护活性成分及益生菌中应用的研究进展

随着近几十年来不同纳米技术的迅速发展,将生物活性成分捕获到高分子基质中进行控释已成为一个热门的研究领域。将生物活性成分加入到不同的封装基质中是一种独特的方法,它可以保护这些有价值的成分在不利的体外或体内环境中不致失活,最大限度的提高其稳定性和生物利用率。与传统封装技术相比,静电纺丝技术具有许多优势,如所产纤维的孔隙率高、表面体积比高、结构上与细胞外基质相似以及对生物活性化合物具有高包封率等,这些结构和功能上的优势使得静电纺丝技术在保护生物活性成分方面成为一种更好的选择。本文主要综述了静电纺丝的基本工作原理、纳米纤维聚合物的选择、影响纳米纤维特性的参数,分析了静电纺丝纳米纤维的优势,并探讨了静电纺丝技术在包封不同类型生物活性化合物中的应用,为该技术在食品加工中的深入研究及应用以及相关创新食品的开发提供了参考。     

Effect of garlic, onion, and their combination on the quality and sensory characteristics of irradiated raw ground beef

Irradiated raw ground beef had lower a*- and b*-values than nonirradiated ones regardless of garlic or onion treatment at 0 d. Irradiation increased TBARS values of control ground beef, but addition of 0.5% onion or 0.1% garlic+0.5% onion reduced oxidative changes during storage. Addition of garlic or onion greatly increased the amounts of sulfur compounds, but the increase was greater with garlic. With irradiation, the profiles and amounts of S-volatiles in raw ground beef changed significantly. However, the intensity of irradiation aroma in irradiated raw ground beef with garlic or onion was similar to that of the nonirradiated control. This indicated that some of the sulfur compounds unique to garlic or onion interacted with common sulfur compounds detected in irradiated meat and masked or changed the odor characteristics of irradiated raw ground beef. It was concluded that >0.5% onion or <0.01% garlic would be needed to mask or prevent irradiation aroma in irradiated raw ground beef.     

Addition of garlic or onion before irradiation on lipid oxidation, volatiles and sensory characteristics of cooked ground beef

Addition of 0.5% onion was effective in reducing lipid oxidation in irradiated cooked ground beef after 7 day storage. Addition of garlic or onion greatly increased the amounts of sulfur volatiles from cooked ground beef. Irradiation and storage both changed the amounts and compositions of sulfur compounds in both garlic- and onion-added cooked ground beef significantly. Although, addition of garlic and onion produced large amounts of sulfur compounds, the intensity of irradiation odor and irradiation flavor in irradiated cooked ground beef was similar to that of the nonirradiated control. Addition of garlic (0.1%) or onion (0.5%) to ground beef produced a garlic/onion aroma and flavor after cooking, and the intensity was stronger with 0.1% garlic than 0.5% onion treatment. Considering the sensory results and the amounts of sulfur compounds produced in cooked ground beef with added garlic or onion, 0.5% of onion or less than 0.1% of garlic is recommended to mask or change irradiation off-odor and off-flavor.     

以多糖和蛋白质为基质利用静电纺丝技术构建生物活性物质递送体系的研究进展

食品在加工和储藏过程中会受到高温、离子强度、酸碱性等诸多因素的影响,导致其生物活性物质极其不稳定。同时,如果这些生物活性物质直接暴露于胃肠道环境中,其生物利用率迅速降低且容易被降解,这些不利因素极大地限制了生物活性物质在食品工业化生产中的应用。因此,如何有效地包埋生物活性物质成为研究的热点问题。静电纺丝技术是一种新兴的活性物质包埋技术,利用该技术制备的纳米纤维在食品工业中具有潜在的应用价值。本文主要综述了静电纺丝的原理、影响因素和类型,以天然多糖和蛋白质为基质通过静电纺丝制备生物活性物质递送体系(纳米纤维)的研究进展,纳米纤维的制备过程、影响因素及其改善方法,并展望了静电纺丝在食品科学领域中的应用前景。     

Electrospinning of nanofibers: Potentials and perspectives for active food packaging

Electrospun nanofibers with structural and functional advantages have drawn much attention due to their potential applications for active food packaging. The traditional role of food packaging is just storage containers for food products. The changes of retailing practice and consumer demand promote the development of active packaging to improve the safety, quality, and shelf life of the packaged foods. To develop the technique of electrospinning for active food packaging, electrospun nanofibers have been covalently or non‐covalently functionalized for loading diverse bioactive compounds including antimicrobial agents, antioxidant agents, oxygen scavengers, carbon dioxide emitters, and ethylene scavengers. The aim of this review is to present a concise but comprehensive summary on the progress of electrospinning techniques for active food packaging. Emphasis is placed on the tunability of the electrospinning technique, which achieves the modification of fiber composition, orientation, and architecture. Efforts are also made to provide functionalized strategies of electrospun polymeric nanofibers for food packaging application. Furthermore, the existing limitations and prospects for developing electrospinning in food packaging area are discussed.     

静电纺丝技术包埋天然酚类化合物研究进展

天然酚类化合物因其对人体健康具有众多益处,近年来在食品、营养学和医药等领域得到了广泛的关注。然而,酚类化合物较差的溶解性、稳定性和生物利用度等严重地限制了其应用。如何有效地保护和运载这些酚类化合物并保持其生物活性成为研究的热点问题。静电纺丝是一种易于操作且成本低廉的纳米级纤维制备技术,所制备的纳米纤维可作为纳米载体对生物活性物质进行包埋和控制释放,因此可作为包埋酚类化合物的一种有效方法。本文概述了静电纺丝技术的基本原理、类型、影响参数、常用的聚合物基质和优势,对静电纺丝技术包埋天然酚类化合物的相关研究进行了综述,最后展望了其在食品工业的应用前景,以期为静电纺丝技术在食品领域应用提供一定的理论指导。     

Characterizing Red Radish Pigment Off-Odor and Aroma-Active Compounds by Sensory Evaluation,Gas Chromatography-Mass Spectrometry/Olfactometry and Partial Least Square Regression

Aroma-active compounds of red radish pigment extracts (water extract, phosphoric acidified water extracts (PAW), 10 min water or phosphoric acidified water preheated extracts (HW or HPAW), Chongqing, and Yunan extracts) were identified and characterized via sensory evaluation, gas chromatography-mass spectrometry (GC-MS), and gas chromatography-mass spectrometry with olfactometry (GC-MS/O). Three sensory attributes, namely radish odor (desirable) and radish off-odor and sulfur-like odor (undesirable), were selected to characterize the red radish pigment extracts. The correlation between the aroma-active compounds (GC-MS) and sensory attributes was studied using partial least square regression (PLSR). The sensory evaluation results revealed that Chongqing (9.30 and 8.80), water (9.00 and 9.10), Yunan (7.80 and 8.00), and HW (6.90 and 7.20) extracts showed higher radish off-odor and sulfur-like odor scores, while PAW-2.5 (7.70) and HPAW-2.5 (7.60) extracts showed higher radish odor scores. Sulfur-containing compounds, allyl isothiocyanate, 1-butyl isothiocyanate, acetonitrile, oxygen-containing compounds, terpenes, and naphthalene were positively and significantly correlated with radish off-odor and sulfur-like odor but negatively and significantly correlated to radish odor. 3-(Methylthio)propyl isothiocyanate and pyridine were positively and significantly correlated to radish odor. Additionally, 3-buten-1-yl isothiocyanate and 4-(methylthio)-3-butenyl isothiocyanate showed positive but not significant impact on radish odor. Based on their higher volatile concentration, the aroma-active compounds of the four extracts were evaluated using GC-MS/O. Thirty-three aroma-active compounds with different odor intensities were identified to be the major odorant compounds for red radish pigment extracts by panelists. Conclusively, the red radish pigment extraction conditions play a great role in its sensory characteristics.     

Discrimination of Swiss Cheese from 5 Different Factories by High Impact Volatile Organic Compound Profiles Determined by Odor Activity Value Using Selected Ion Flow Tube Mass Spectrometry and Odor Threshold

Swiss cheese contains more than 200 volatile organic compounds (VOCs). Gas chromatography‐mass spectrometry has been utilized for the analysis of volatile compounds in food products; however, it is not sensitive enough to measure VOCs directly in the headspace of a food at low concentrations. Selected ion flow tube mass spectrometry (SIFT‐MS) provides a basis for determining the concentrations of VOCs in the head space of the sample in real time at low concentration levels of parts per billion/trillion by volume. Of the Swiss cheese VOCs, relatively few have a major impact on flavor quality. VOCs with odor activity values (OAVs) (concentration/odor threshold) greater than one are considered high‐impact flavor compounds. The objective of this study was to utilize SIFT‐MS concentrations in conjunction with odor threshold values to determine OAVs thereby identifying high‐impact VOCs to use for differentiating Swiss cheese from five factories and identify the factory variability. Seventeen high‐impact VOCs were identified for Swiss cheese based on an OAV greater than one in at least 1 of the 5 Swiss cheese factories. Of these, 2,3‐butanedione was the only compound with significantly different OAVs in all factories; however, cheese from any pair of factories had multiple statistically different compounds based on OAV. Principal component analysis using soft independent modeling of class analogy statistical differentiation plots, with all of the OAVs, showed differentiation between the 5 factories. Overall, Swiss cheese from different factories was determined to have different OAV profiles utilizing SIFT‐MS to determine OAVs of high impact compounds.     

臭氧水处理对冷藏期内草鱼鱼片挥发性成分的影响

为研究臭氧水处理对草鱼鱼片挥发性成分的影响,本文采用快速气相电子鼻、顶空固相微萃取结合气相色谱-质谱联用(Gas chromatography-mass spectrometry,GC-MS)的方法对对照组、4 min处理组和8 min处理组在4 ℃冷藏0、5以及10 d时的样品进行检测分析。主成分分析(principal components analysis,PCA)与判别因子分析(discriminant factor analysis,DFA)结果表明臭氧水处理可有效改变草鱼鱼片的挥发性成分,贮藏期各样品气味差异明显;GC-MS检测发现整个贮藏期间样品包含43种主要挥发性物质,新鲜样品中主要含有己醛、戊醛、1-辛烯-3-醇、2,3-辛二酮等土腥气味物质,这些物质经臭氧水处理后可被有效去除,且去除效果随处理时间延长而增强;在贮藏期内,样品挥发性成分变化较大,但臭氧水处理组所含硫代乙酸甲酯、吲哚以及胺类等具有腐臭气味的挥发性物质含量均低于对照组。臭氧水处理可有效去除新鲜草鱼鱼片的土腥气味并具有延缓贮藏期内样品腐臭气味产生的作用。     

顶空固相微萃取结合气相色谱-质谱联用法对3种洋葱挥发性风味成分的分析

为研究洋葱挥发性成分,利用顶空固相微萃取法提取洋葱的挥发性风味成分,通过气相色谱-质谱联用法分析测定,以总峰面积和化合物个数为指标考察萃取纤维头、萃取温度、萃取时间和解吸时间4个因素对萃取效果的影响,得出最优萃取条件为:萃取纤维头50/30 μm DVB/CAR/PDMS,萃取温度60 ℃,萃取时间60 min,解吸时间5 min。利用最优萃取条件对三种色泽洋葱挥发性风味成分进行分析鉴定。结果表明:三种色泽洋葱共鉴定得到挥发性风味物质61种,其中白皮、红皮、黄皮洋葱分别测到37、40、49种挥发性成分,相对含量分别占流出组分总量的70.29%、81.92%、79.03%。61种挥发性成分中含硫化合物27种、醛类13种、醇类13种、酮类4种,其他4种。三种色泽洋葱的共有挥发性成分有22种,其中含硫化合物占比较大,特别是二异丙基二硫醚和(E)-1-丙烯基-2-丙烯基二硫醚相对含量的总和在三种色泽洋葱的挥发性成分中占比率都超过了20%,对形成洋葱特征风味贡献较大。红皮和黄皮洋葱的含硫化合物的相对含量远高于白皮洋葱,红皮洋葱中2-甲基-2-戊烯醛相对含量高于白皮和黄皮洋葱。     

Microencapsulation of Propolis in Protein Matrix Using Spray Drying for Application in Food Systems

Propolis presents several health benefits due to the presence of bioactive compounds, mainly phenolic compounds; however, its application in food is limited due to undesirable odor and low water solubility. The bioactive compounds are usually susceptible to degradation by exposure to light, heat, or oxygen or by interaction with other compounds, which may limit its biological activity. The study aimed the propolis extract microencapsulation using rice, pea, soybean, and ovoalbumin proteins as wall material by spray drying and to analyze their in vitro digestion. The propolis extract presented a high concentration of apigenin. Encapsulation efficiency was greater than 70%, and it was maintained the antioxidant activity of propolis (88% inhibition of DPPH for propolis extract and >?73% for the microparticles). The DSC, ATR-FTIR, and X-ray diffraction techniques confirmed the encapsulation. The microparticles showed different shapes, sizes, and physical characteristics. The microparticles encapsulated with pea protein could be used in formulations of Minas Frescal cheese due to the controlled released, whereas the other microparticles could be used in pudding formulations.     

Assessment of antioxidant activity and phycocyanin release of Spirulina loaded poly(ε-caprolactone) electrospun nanofibers

PCL with biodegradable property and Spirulina with various biological activities offer good alternative ingredients for the fabrication of functional nanofibers in tissue engineering. The aim of the study is to obtain PCL/Spirulina nanofibers with low diameters and to determine their wettability, antioxidant activity, and phycocyanin release to evaluate their potential as bioactive scaffolds in different applications. PCL/acetic acid/pyridine solutions with three different Spirulina concentrations were electrospun and the obtained nanofibers were investigated. The thinnest PCL/Spirulina nanofibers (117.20 nm) were obtained at 1.5% Spirulina concentration. Although PCL nanofibers with 6% Spirulina concentration showed the highest antioxidant activity and amount of phycocyanin released, PCL nanofibers with 3% Spirulina concentration having similar in vitro results showed superiority when considering the diameter and uniformity of the nanofibers and the cost of the material. The PCL/Spirulina nanofibers with small diameters and antioxidant activity could be regarded as potential extracellular matrix material for tissue engineering.     

Characterisation of onion (Allium cepa L.) by-products as food ingredients with antioxidant and antibrowning properties

Processing and stabilising onion wastes (residues and surpluses of onion) could solve the environmental problem derived from a great onion wastes disposal. Moreover, obtaining stabilised onion by-products as natural antioxidant food ingredients could be advantageous to food industry, not only to improve the use of onion wastes but also to obtain new natural and functional ingredients. The aim of this study was to characterise onion by-products – juice, paste and bagasse – from two Spanish onion cultivars – ‘Figueres’ and ‘Recas’ – that have been stabilised by thermal treatments – freezing, pasteurisation and sterilisation – in order to evaluate the effect of the processing and stabilisation treatment on the bioactive composition, antioxidant activity and polyphenol oxidase (PPO) enzyme inhibition capacity. The results obtained triggered to choose one onion by-product offering better characteristics for its potential development as a food ingredient: source of antioxidant and antibrowning bioactive compounds. In this study it was shown that processing of ‘Recas’ onion wastes to obtain a paste (mixture content) and applying a mild pasteurisation were the best alternatives to obtain an interesting stabilised onion by-product with good antioxidant properties that made useful its use as functional food ingredient.     

The thermostability, bioactive compounds and antioxidant activity of some vegetables subjected to different durations of boiling: Investigation in vitro

This research was performed in order to compare the water and acetone extracts of raw and boiled for 10, 20, 40 and 60 min Korean lotus roots (KLR) and Polish white onion (PWO) in the contents of their bioactive compounds, antioxidant activity and thermostability.It was found that polyphenols (mg GAE/g), flavanols (μg GAE/g), flavonoids (mg CE/g), anthocyanins (mg CGE/kg) and tannins (mg CE/g) in water extract of raw lotus roots were 14.18 ± 0.7, 8.41 ± 0.5, 1.09 ± 0.06, 21.3 ± 1.2 and 7.29 ± 0.4, and of white onion - 11.11 ± 0.6, 6.78 ± 0.3, 0.71 ± 0.03, 17.00 ± 0.9 and 1.64 ± 0.08, respectively, and significantly higher in KLR (P < 0.05). The antioxidant activity of raw KLR water extract (139.4 ± 6.1, 53.1 ± 3.6 and 89.3 ± 4.6 μmol TE/g for DPPH, CUPRAC and ABTS, respectively) was significantly higher than in white onion (23.84 ± 1.8, 31.9 ± 2.1 and 38.14 ± 2.6 for DPPH, CUPRAC and ABTS, respectively, P < 0.05).The thermostability of the water KLR extract’s of polyphenols, flavanols, flavonoids, anthocyanins and tannins was high and even after 60 min of boiling remains as 40.0, 42.3, 50.5, 41.4 and 41.0%, respectively. After 60 min of boiling the most thermostable compounds were flavonoids - remaining at 50.5% in water extract of KLR. Also after 60 min of boiling the thermostability of the antioxidant activity of water extracts of KLR remained significantly high: 40.6, 42.3, 46.3 and 43.6%, according to DPPH, FRAP, ABTS and CUPRAC assays, respectively.Similar relationship was obtained with acetone extracts, but the value was lower than with the water ones. In conclusion, the contents of some bioactive compounds, the antioxidant activity and the thermostability in water and acetone extracts of KLR are significantly higher than the same indices in PWO. FTIR and fluorimetry can be used as additional markers for the characterization of bioactive compounds in vegetables.     

洋葱中黄酮类化合物的分布及其抗氧化活性的研究

洋葱是黄酮类化合物含量较高的蔬菜之一,本研究对新疆产的红皮洋葱、黄皮洋葱和白皮洋葱等3个主要的洋葱品种分别采用浓度为95%和60%的乙醇溶液提取其中的黄酮类化合物,并比较了各种提取物对羟基自由基和DPPH自由基清除能力。结果表明,三个品种中的黄酮类化合物的含量以红洋葱最高,黄洋葱次之,白洋葱的含量最低,洋葱提取物的抗氧化能力与其中的黄酮类化合物的含量呈正相关关系。     

Processes to Preserve Spice and Herb Quality and Sensory Integrity During Pathogen Inactivation

Selected processing methods, demonstrated to be effective at reducing Salmonella, were assessed to determine if spice and herb quality was affected. Black peppercorn, cumin seed, oregano, and onion powder were irradiated to a target dose of 8 kGy. Two additional processes were examined for whole black peppercorns and cumin seeds: ethylene oxide (EtO) fumigation and vacuum assisted‐steam (82.22 °C, 7.5 psia). Treated and untreated spices/herbs were compared (visual, odor) using sensory similarity testing protocols (α = 0.20; β = 0.05; proportion of discriminators: 20%) to determine if processing altered sensory quality. Analytical assessment of quality (color, water activity, and volatile chemistry) was completed. Irradiation did not alter visual or odor sensory quality of black peppercorn, cumin seed, or oregano but created differences in onion powder, which was lighter (higher L^*) and more red (higher a^*) in color, and resulted in nearly complete loss of measured volatile compounds. EtO processing did not create detectable odor or appearance differences in black peppercorn; however visual and odor sensory quality differences, supported by changes in color (higher b^*; lower L^*) and increased concentrations of most volatiles, were detected for cumin seeds. Steam processing of black peppercorn resulted in perceptible odor differences, supported by increased concentration of monoterpene volatiles and loss of all sesquiterpenes; only visual differences were noted for cumin seed. An important step in process validation is the verification that no effect is detectable from a sensory perspective.     

Effects of onion on physicochemical properties,lipid oxidation and microbial growth of fresh pork patties

Onions with or without heating (100 °C, 30 min) were extracted with water or methanol, and antioxidant and antimicrobial activities of onion extracts were evaluated. Product characteristics of fresh pork patties containing various onion extracts were measured during refrigerated storage. Water extracts of onions showed higher extraction yield and iron chelating ability than methanol extracts (P < 0.05), whereas, the latter was more effective than the former in phenolic compounds and reducing power (P < 0.05). The addition of onion extracts [water extract from fresh onion (WEFO), methanol extract from heated onion (MEHO) and their combinations (WEFMEHO)] to pork patties decreased redness, increased yellowness, and inhibited lipid peroxidation (P < 0.05). One per cent of WEFMEHO in pork patties had antioxidant activities as effective as butylated hydroxyl toluene (BHT, 0.01%). Redness and yellowness decreased and increased with the addition of onion extract, respectively (P < 0.05).