Spray-dried zein capsules with coencapsulated nisin and thymol as antimicrobial delivery system for enhanced antilisterial properties

Food grade antimicrobial delivery systems were studied in this work to enhance the effectiveness of antimicrobials inhibiting the growth of Listeria monocytogenes during storage. Corn zein was used as a carrier biopolymer and nisin and thymol as antimicrobials. Capsules produced by spray drying demonstrated different microstructures and release characteristics of nisin at different usage levels of thymol. Better release profiles were achieved when glycerol was additionally used to prepare capsules. Capsules showing sustained release of significant amounts of both antimicrobials effectively inhibited the growth of L. monocytogenes at pH 6.0 and 30 °C in the growth medium. Capsules were also more effective than free antimicrobials in inhibiting the growth of L. monocytogenes in 2% reduced fat milk at 25 °C. Our work showed that engineered delivery systems have promise to fulfill the antimicrobial effectiveness during shelf life storage of foods to ensure microbiological safety.     

alpha-Casein improves the gel properties of dried egg white

The effects of addition of alpha-casein (alpha-CN) to dried egg white (DEW) were investigated by measuring transparency, hardness, and water-holding capacity (WHC) of the heat-induced gels. A DEW concentration of 8% (w/w) was required for formation of a self-supporting gel following heating at 80 degrees C for 20 min at pH 7. Solutions of alpha-CN, even up to a protein concentration of 12% (w/w), did not gel under the same conditions. The addition of alpha-CN (0.5-4%) to 8% DEW caused the increase in gel hardness gels, as compared with DEW gels alone at a total amount of protein concentrations, and the mixed gels became transparent with the increase of added alpha-CN concentrations. The 10% mixed protein solutions of alpha-CN (3-6%) and DEW (4-7%) formed transparent gels, although each protein did not gel individually at their protein concentrations. Mixture with 2:8 mixing ratio of alpha-CN to DEW at a total protein concentration of 10% showed synergistic effects in improving DEW gel properties above pH 7 and below 25 mM NaCl. The improvements (hardness, transparency, and WHC) of DEW gel by alpha-CN seem to be caused mainly by the inhibition of alpha-CN against heat coagulation of DEW protein.     

Ultrasonic spectroscopy and differential scanning calorimetry of liposomal-encapsulated nisin

The thermal stability of phosphatidylcholine (PC) liposomes (colloidal dispersions of bilayer-forming polar lipids in aqueous solvents) in the presence and absence of the antimicrobial polypeptide nisin was evaluated using differential scanning calorimetry (DSC) and low-intensity ultrasonic spectroscopy (US). PC liposome mixtures with varying acyl chain lengths (C16:0 and C18:0) were formed in buffer with or without entrapped nisin. Gel-to-liquid crystalline phase transition temperatures (T(M)) of liposomes determined from DSC thermograms were in excellent agreement with those determined by ultrasonic velocity and attenuation coefficient measurements recorded at 5 MHz. The dipalmitoylphosphatidylcholine (DPPC) T(M) measured by DSC was approximately 41.3 and approximately 40.7 degrees C when measured by ultrasonic spectroscopy. The T(M) of distearoylphosphatidylcholine (DSPC) and DPPC/DSPC 1:1 liposomes was 54.3 and 54.9 degrees C and approximately 44.8 and approximately 47.3 degrees C when measured by DSC and US, respectively. The thermotropic stability generally increased upon addition of nisin. Analysis of the stepwise decrease in ultrasonic velocity with temperature indicated an increased compressibility corresponding to a loss of structure upon heating.     

膜材料及其构成对调节控释肥料养分释放特性的影响

试验采用水溶出率实测法研究了自行研制的控释肥料养分释放的特性。以养分释放速率和释放期为主要指标评价了膜材料及其构成对调节控释肥养分释放特性的影响。结果表明,膜材料M2的控释性能优于膜材料M1;用膜材料M1包膜肥料的养分累积释放曲线呈对数曲线,而用膜材料M2包膜肥料的养分累积释放曲线呈直线型。在膜的比面重(单位肥料面积上所含膜材料的重量)为20～80g/m2范围内,随着比面重的增加,包膜肥的初期溶出率降低,释放期延长;通过调节膜材料组成与比面重可以研制出释放期不同的控释肥料。     

Differential effects of soil properties on leaf nitrogen release

 Identifying the determinants of the N dynamics of plant prunings or litter is important for the efficient management of agroecosystems in order to improve their productivity. The plant materials in these ecosystems are managed as soil surface mulches or are incorporated into the soil. Numerous studies have been conducted to investigate which plant chemical parameter best governs N release. In these studies, different plant materials have been incorporated into a soil with a set of known characteristics. The objective of the present study was to examine the effects of different soil properties on N release from plant leaves, when they were incorporated into soils under non-leaching conditions. A laboratory incubation experiment (for 8 weeks) was carried out with dried and ground leaves of six leguminous plants and wild sunflower, which were mixed with three soils (alfisol; ultisol, udult; ultisol, humult). Leaf cellulose was the major chemical parameter that determined leaf N release in the alfisol and ultisol, udult. In the ultisol, humult, the C/N ratio and hemicellulose concentration were better related to N release. Cellulose was not a good indicator of N release in the ultisol, humult, possibly due to a low soil pH which did not favour the activity of the cellulose-degrading enzymes of microbes active in decomposition. Soil pH determined the specific C source that was used to generate energy for microbial action and N mineralization/immobilization. It also had an effect on the nitrification of the mineralized N. The levels of labile soil C fractions governed the mode or nature of N release (i.e. mineralization or immobilization). The levels of labile leaf C fractions incorporated into the soils governed the extent of N release. The soil N concentration in the decomposable organic matter pool, as compared to the leaf N concentration, determined whether leaf N limited its own release. It is recommended from this study that, in grouping different leaf materials as sources of N, the properties of soils into which they are incorporated should also be considered, in addition to leaf quality in terms of its chemical composition. In future studies, the relationships identified under laboratory conditions in this experiment should be verified under field conditions. Received: 3 December 1997     

Combined application of biochar with compost and fertilizer improves soil properties and grain yield of maize

A pot study was conducted to assess the combined effect of biochar (B) with compost (Com) and inorganic fertilizers (F) for improving nutrient acquisition and productivity of maize. Seven different treatments, including B (1% w/w), F (Recommended nitrogen, phosphorus and potassium (NPK): 60, 30 and 25 mg kg^─1), Com (1.5% w/w), Com+F (1.5% + NPK), B+F (1% + NPK), B+Com (0.5% + 0.75%), B+Com+F (0.5% + 0.75% + NPK) along with a control (C) without B, Com and F were applied in pots with four replications. The results showed that growth and grain yield of maize increased by the application of B, Com and F compared with C, but B+Com+F was more effective than their sole application (i.e. B, Com and F). Highest leaf chlorophyll content, gas exchange attributes and nutrient concentrations: N, P and K in shoot and grains were observed, where B+Com+F was applied followed by Com+F > B+F > B+Com > F > Com > B > C. Soil properties such as soil organic carbon (SOC), N, P, and K were significantly increased, whereas soil pH was decreased by the combination of B with Com and F. Hence, application of B in combination with Com and F (B+Com+F) could be a good management strategy to enhance crop productivity and improve soil properties.     

炭肥比和膨润土粘结剂对炭基肥颗粒理化及缓释特性的影响

为探究炭肥比和膨润土粘结剂对生物炭基肥理化及缓释特性的影响,以生物炭为基底,分别制备了炭肥比1:4,膨润土粘结剂质量分数为20%、15%、10%、5%和粘结剂质量分数10%,炭肥比为1:6、1:5、1:4、1:3的柱状尿素和氯化钾生物炭基肥颗粒,分析了生物炭基肥颗粒的理化及缓释特性。结果表明,在炭肥比为1:4条件下,膨润土粘结剂质量分数越高,生物炭基肥微观结构越紧密,力学和缓释特性越好,质量分数为20%时,氯化钾和尿素生物炭基肥平均抗压强度分别为286.78和281.27 N,前3天养分淋出率分别为45.53%和36.87%。在膨润土粘结剂质量分数为10%条件下,炭肥比越高,生物炭基肥缓释性能越好,炭肥比为1:3时,氯化钾和尿素生物炭基肥前3天养分淋出率分别为42.06%和40.32%。同时,氯化钾生物炭基肥表面孔隙先增后减,炭肥比为1:6和1:3的平均抗压强度分别为271.25和282.42 N。尿素生物炭基肥内部结构中孔隙变多,炭肥比为1:6时,平均抗压强度为最大值267.84 N。综合考虑,满足中等肥料浓度要求时,膨润土粘结剂质量分数为20%、炭肥比为1:4或膨润土粘结剂质量分数为10%、炭肥比为1:3的生物炭基肥成型配方较优。     

Involvement of dehydroalanine and dehydrobutyrine in the addition of glutathione to nisin

Nisin variants and fragments were reacted with glutathione, and the products of the reactions were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography/mass spectrometry (LC-MS). Reactions between glutathione and either [Ala5]nisin or [Ala33]nisin resulted in products with two glutathione molecules conjugated to one nisin variant molecule. Only one glutathione molecule was added to [Ala5,Ala33]nisin. Fragmentation of the nisin molecule resulted in nisin 1-12, nisin 1-20, and nisin 1-32 fragments. Each fragment retained two dehydro residues, which subsequently underwent reaction with glutathione. The data indicated that the dehydroalanine residues of nisin are sites of addition for glutathione. Such addition renders the nisin molecule inactive.     

Double mulching improves soil properties and productivity of maize-based cropping system in eastern Indian Himalayas

A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize (Zea mays L.) - based cropping sequences. Results revealed that double mulching with in-situ maize stover mulch (MSM) + fresh biomass of white hoary pea (WHP-Tephrosia candida) and MSM + fresh biomass of ragweed (RW- Ambrosia artemisiifolia) improved soil moisture content (SMC) and leaf relative water content of crops during dry season. The soil organic carbon (SOC) content and stocks under MSM + WHP and MSM + RW mulches were significantly higher than that under no mulch at 0–15 cm depth. The soil microbial biomass carbon and dehydrogenase activity were maximum under MSM + WHP/RW. The highest system productivity was obtained from maize-French bean (Pole type-PT) sequence under MSM + RW followed by MSM + WHP. The water productivity was the highest under MSM + WHP. While SOC content was the highest under maize-French bean (PT), the maximum plant available nitrogen and phosphorus were obtained under maize-black gram sequence.Thus, double mulching technology involving MSM and RW (available in plenty) is a viable option for improving soil, crop and water productivity under rainfed hill ecosystems of eastern Indian Himalayas.     

Delayed volatile compound release properties of self-assembly structures in emulsions

Temporal release and retention of aroma compounds from structured emulsions (where unsaturated monoglycerides are added to the oil) and conventional oil-in-water emulsions were studied using in vitro dynamic headspace analysis by proton-transfer reaction mass spectrometry and static headspace analysis by gas chromatography-mass spectrometry. Under dynamic conditions, the structured emulsion exhibited delayed release compared to the oil-in-water emulsion containing the same lipid content of 5%. The time to maximum concentration T max of amphiphilic and lipophilic aroma compounds increased by a factor of 1.2 (for 3 E-hexenal) to 1.9 (for octanal). The aroma release profile of the 5% lipid structured emulsion was close to that obtained for the oil-in-water emulsion containing 10% lipid. Under static conditions, the 5% lipid structured emulsion retained more of the most lipophilic aroma compounds than its counterpart 5% oil-in-water nonstructured emulsion. The present study provides potential solutions for modulating aroma release profiles of reduced-fat foods by self-assembly structures.     

改性玉米秸秆复合高吸水树脂的尿素吸收及缓释性能

为了提高化肥的利用率、降低环境污染和提高玉米秸秆的高附加值综合利用水平,以过硫酸铵和亚硫酸氢钠为氧化还原引发剂,将植酸改性玉米秸秆与衣康酸、乙烯基吡咯烷酮和丙烯酰胺接枝共聚制备植酸改性玉米秸秆复合高吸水性树脂（PCS-SA,phytic acid-modified corn stalk-composite superabsorbent）,该文重点研究了衣康酸与乙烯基吡咯烷酮质量比对PCS-SA尿素溶液吸肥速率、保肥率以及缓释速率的影响,采用扫描电镜（SEM,scanning electronic microscope）和傅里叶红外光谱（FTIR,fourier transform infrared spectroscopy）对PCS-SA的结构和形貌进行了表征。结果表明衣康酸与乙烯基吡咯烷酮质量比为70:30制备的PCS-SA对尿素吸附量为3.81 g/g,40 min尿素溶液吸肥率达到最大值（360 g/g）,PCS-SA吸肥凝胶去离子水中3 d尿素释放率为66.14%,在土壤中5 d尿素释放率为47.6%,明显降低了尿素的释放速率、提高了土壤的保肥能力。FTIR谱图初步证实PCS-SA的结构,SEM表明PCS-SA具有不规则的凹凸波状表面,并伴有许多大微孔和小毛细孔。该研究为PCS-SA在农林等领域的应用提供试验依据和参考。     

膜特性对包膜控释肥养分控释性能的影响

为了研究膜特性对包膜控释肥养分控释性能的影响,该文通过膜的拉伸试验、扫描电镜和养分水中溶出率法对P1和P2树脂膜（不同包膜比率,不同添加剂含量）的机械性质、微观结构和养分控释特性进行了研究,结果表明,P1树脂膜机械性能较差,易发生龟裂现象,且通透性较大;P2树脂膜机械性能较好,但通透性较差;仅通过改变包膜比率不能达到改变两种膜的控释性能的目的。在不同包膜比率两种膜中分别添加适量的高分子疏水物质和可降解改性淀粉,可明显改善膜壳的机械性质、微观结构并起到了对养分释放速率的调控作用。两种膜材料包膜的控释肥料的控释性能均可通过改变各自的包膜比率和添加物的比例来调控,其关系可用函数关系模拟,且拟合度均达到显著水平。     

添加固体颗粒提高太阳能集热管内导热油光热转换性能

利用太阳辐照玻璃真空管加热导热油的试验装置,试验研究了添加不同种类和不同质量分数的固体颗粒对导热油光热转换特性的影响,通过测量闷晒温度和闷晒太阳辐照量间接比较了3种试验流体的热性能;理论分析了固体颗粒对导热油吸热与对流传热的强化机理。结果表明：添加铜箔颗粒可提高导热油平均温度14℃;同等试验工况石墨-油分别与铜箔-油和铝箔-油的最大温差达3.3和7℃;质量分数3%～3.2%的铜箔颗粒对提高导热油闷晒温度较有利,增大含量对光热转换的强化效果不明显。石墨-油和铜箔-油显示出良好的光热转换性能。该研究为导热油在太阳能热发电和热管热水器领域的应用提供科学参考。     

松香凹凸棒石粘土包膜尿素的制备及缓释性能的研究

矿物和有机物复合包膜有利于提高肥料的利用效率.以松香的无水乙醇溶液为粘结剂,凹凸棒石粘土作为内包层,石蜡作为外层,采用熔融喷雾包膜的方法制备一种缓释包膜尿素.通过扫描电镜( SEM)分析得出,尿素内部形成一层以松香和凹凸棒石粘土为内包层的均匀膜,根据水浸泡试验和抗压强度测定表明,添加凹凸棒石粘土增加了包膜层的强度,松香...     

Resveratrol nanoparticle system improves dissolution properties and enhances the hepatoprotective effect of resveratrol through antioxidant and anti-inflammatory pathways

Resveratrol (RES), a well-known antioxidant and anti-inflammatory compound, is abundant in red wine and exerts numerous pharmacological effects, including hepatoprotection and cadioprotection. Unfortunately, RES is restricted in clinical application due to poor dissolution property and adsorption. In addition, red wine as a supplement for preventing disease is not recommended for patients with alcohol-related disorders. To address these limitations, we successfully developed a novel RES nanoparticle system (RESN) and demonstrated that RESN could circumvent the physicochemical drawbacks of raw RES with respect to dissolution, such as the reduction of particle size, amorphous transformation, and hydrogen-bond formation. In addition, we employed an animal model of CCl?-induced hepatotoxicity to estimate the potential of the nanoparticle formulation to improve the hepatoprotective effect of orally administered RES. Our results demonstrated that RESN can diminish liver function markers (aspartate aminotransferase and alanine aminotransferase) by decreasing hepatocyte death due to CCl?-induced hepatotoxicity in rats, when compared with RES administration. The effect was achieved by reducing oxidative stress (decreased reactive oxygen species and lipid peroxidation) and lowering inflammatory cytokines (decreased tumor necrosis factor-α and interleukin 1β) and protein expression (cyclooxygenase-2, inducible nitric oxide synthase, cytosolic phospholipase A2, and caspase-3). In conclusion, enhancement of the dissolution of RES through a nanoparticle engineering process can result in increased hepatoprotective effects mediated by antioxidant and anti-inflammatory activities. Consequently, we suggest that RESN deserves further study, perhaps in prophylaxis of chronic liver diseases.     

Comparative study on the antioxidant and biological activities of carvacrol, thymol, and eugenol derivatives

Four derivatives of thymol, carvacrol, and eugenol were synthesized: 4-(hydroxymethyl)-5-isopropyl-2-methylphenol, 4,4'-methylenebis(5-isopropyl-2-methyl)phenol, 4-allyl-6-(hydroxymethyl)-2-methoxyphenol, and 4-(hydroxymethyl)-2-isopropyl-5-methylphenol. The obtained derivatives showed remarkably better antioxidative properties according to 1,1-diphenyl-2-picrylhydrazyl assay (50% inhibitory concentrations = 4-156 microg/mL) and Rancimat assay (protection factors = 1.55-5.84) when compared with parent compounds and values similar to or better than those of butylated hydroxytoluene and vitamin C. At concentrations of 10 mM carvacrol derivatives had no toxic effect on viability of Escherichia coli K-12 (determined by minimum inhibitory concentrations). Other phenol derivatives showed reduced cytotoxic effect on E. coli K-12 at concentrations of 2-5 mM on the basis of 50% lethal dose measurements. In comparison with the parent compounds, phenol derivatives showed reduced cytotoxic effect for Saccharomyces cerevisiae cells (determined by yeast colony reduction). On the other hand, the majority of synthesized compounds had dose-dependent antiproliferative effects on human uterine carcinoma cells (HeLa), which makes them potentially interesting for the adjuvant experimental cancer treatments. The 4,4'-methylenebis(5-isopropyl-2-methyl)phenol derivative of carvacrol showed lower inhibiting capacity also for the HeLa cells, which makes this particular derivative attractive as an efficient antioxidant with negligible cytotoxic effects.     

改性聚丙烯酸酯制备包膜缓释肥性能研究

为制备一种可以用于水稻种肥同播的缓控释肥料,试验以甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)为主要材料,并使用少量的羧甲基纤维素(CMC)和纳米SiO₂改性材料,制备改性聚丙烯酸酯乳液包裹肥料以达到缓释效果。选用25℃静水溶出率法,结合红外、电子显微镜等分析技术,探索了不同的原料配比和3种包膜量(10%、15%、20%)制备的改性聚丙烯酸酯缓释肥在水中的养分释放规律。结果表明：在CMC质量占固含量(BA+MMA)的5%且包膜量为20%时缓释效果最好,其在第1和28 d的累积养分释放率分别为0.5%和63.8%,低于15%和80%的限值。使用此规格的自制缓释肥进行了盆栽试验,比较了在不同施肥量和施肥方式下盆面水中全氮、全磷的含量以及水稻生长状况的差异。研究表明,缓释肥施用量为传统施肥量的70%时,相较于传统施肥方式,分别降低56.4%和88.9%的全氮和全磷流失的同时也保证了水稻的产量。     

Flavored yogurt complex viscosity influences real-time aroma release in the mouth and sensory properties

The influence of flavored yogurt texture on aroma perception and in-nose aroma release measured by atmospheric pressure chemical ionization mass spectrometry analysis was investigated. The study was carried out on six yogurts varied by protein composition and mechanical treatment. For the same matrix composition, the complex viscosity of yogurts influenced in-nose release and perception. After swallowing, aroma release and intensity of olfactory perception were stronger in low-viscosity yogurts than in high-viscosity yogurts. Moreover, the protein composition influenced aroma release only when yogurts exhibited wide variations of complex viscosity and consequently texture. In mouth, aroma release and perception were influenced more by yogurt mechanical treatment than by protein composition. On the basis of mass transfer analysis, the main physical mechanism which could explain the difference in aroma release would be the surface exchange area developed in the mouth and in the throat.     

Effects of droplet crystallization and melting on the aroma release properties of a model oil-in-water emulsion

Aroma compounds partition between the dispersed and the continuous phases in emulsions, and phase transitions in the lipid droplets profoundly affect the position of the equilibrium. In the present study, the release of ethyl butyrate, ethyl pentanoate, ethyl heptanoate, and ethyl octanoate from a series of sodium caseinate-stabilized, n-eicosane emulsions was investigated as a function of solid and liquid lipid droplet concentration. For all compounds, headspace volatile concentrations above the solid droplet emulsions were higher than those above the liquid droplet emulsions. The interaction with liquid droplets could be modeled in terms of volume-weighted bulk partition coefficients while the more nonpolar volatiles bound to the surface of solid lipid droplets. The amount of volatiles bound to solid surfaces increased with aqueous concentration up to a critical point and then rapidly increased. The critical point corresponds to the dissolution of the solid lipid in a phase of adsorbed volatile. The binding of volatiles to both solid and liquid eicosane droplets is reversible.     

Vermicompost from biodegraded distillation waste improves soil properties and essential oil yield of Pogostemon cablin (patchouli) Benth

Pre-treatment of patchouli lignocellullosic distillation waste with a consortium of microbes viz. Trichoderma harzianum – ATCC PTA-3701, Pseudomonas monteilii – HQ995498, Bacillus megaterium – ATCC 14581 and Azotobacter chroococcum – MTCC 446 significantly enhanced the bio-degradation of cellulose, hemicelluloses and lignin by 58.44%, 29.44% and 65.23%, respectively and improved the yield of vermicompost by 15%. Application of bioinoculant-enriched vermicompost (BEVC) in patchouli reduced the percent disease index (PDI) of Rhizoctonia root-rot by 36.36% and improved the essential oil yields by 59.74%, 37.70% and 37.96 as compared to plots receiving untreated (not enriched) vermicompost (VC), bioinoculant-enriched compost (BEC) and chemical fertilizers (CF), respectively. Furthermore, BEVC application resulted in a marked improvement in physical (bulk density and water holding capacity) and chemical properties (pH, percent organic carbon, available N, P and K) of the soil. In conclusion, BEVC from distillation waste can be safely utilized as a bio-organic input unambiguously particularly in situations where the use of chemical fertilizers and pesticides is restricted like organic agriculture.