A novel method of shrimp blanching by CO2 heat pump: Quality,energy, and economy analysis

To reduce the energy consumption of the shrimp blanching process and improve the economic value of the blanched product, a transcritical CO₂ heat pump blanching system (THPB system) was designed in this paper. The trends of astaxanthin were investigated at atmospheric pressure near boiling temperature, combined with the color and structural properties of shrimp samples, and the optimal blanching times of 270 s and 240 s were obtained at 90°C and 95°C, respectively. In contrast to the fuel blanching system (FB system) at 100°C, the annual standard coal consumption of the THPB system with 90°C blanching is decreased by 79%, and the annual operating cost can be saved by CNY 63,800, with a payback period of about 3.13 years.Industrial relevanceBlanching is one of the effective ways to prolong the shelf life of shrimp. However, the research on the blanching time and temperature of shrimp is not comprehensive. In addition, the traditional fuel blanching process has high energy consumption and pollution, and can no longer meet the quality requirements of the modern food processing industry. Heat pump has been shown to have better performance in food drying, but it is less used in blanching. The information presented in this study may provide other insights into food processing.     

培养条件对Streptococcus equisimilis合成透明质酸相对分子质量的影响

作者比较了不同培养条件对Streptococcus equisimilis合成透明质酸相对分子质量的影响。结果表明:高质量浓度葡萄糖有利于长链透明质酸的合成,当发酵体系葡萄糖初始质量浓度从20g/L上升至80g/L,相对分子质量从1.24×106增大到2.02×106,提高了62.9%。葡萄糖补料培养不利于高相对分子质量透明质酸的合成,利用葡萄糖间歇和连续补料培养的方式得到透明质酸相对分子质量分别为1.53×106和1.42×106,比分批培养下降了19.9%和25.7%。在33~39℃范围内,较低温度有利于高相对分子质量透明质酸的合成,在33℃培养条件下透明质酸相对分子质量最高可达2.54×106。发酵液p H显著影响透明质酸的相对分子质量,在p H8时,达到了最高的2.38×106。较高溶氧水平有利于高相对分子质量透明质酸的合成,在0~45%溶氧浓度范围内,相对分子质量随溶氧水平的增加从1.16×106提升至2.43×106,增长了109.4%。本研究结果为后续高相对分子质量透明质酸的生产提供有用的实验依据。     

反胶团萃取鱼精蛋白的初步研究

鱼精蛋白是一种重要的药用蛋白质,初步研究了反胶团法提取纯化鱼精蛋白的过程。结果表明,采用2-乙基己基琥珀酸酯磺酸钠（AOT）/异辛烷体系萃取鲑鱼鱼精蛋白,萃取率接近100%,异丙醇显著强化反萃过程。采用反胶团法萃取纯化鱼精蛋白从技术角度来说是可行的。     

Structural and physical properties of soybean protein isolate films with ohmic heating treatment: Impacts of electric field

The effects of ohmic heating (OH) and conventional heating (CON) on the structural and physical properties of soybean protein isolate (SPI) and SPI films were studied. When the electric field was varied from 0 to 12 V·cm⁻¹, the fluorescence intensity, average particle size, and polydispersity index (PDI) of the OH-SPI were the least at 9 V·cm⁻¹ and increased thereafter. Meanwhile, the free SH-group content and surface hydrophobicity were the maximum at 9 V·cm⁻¹ and decreased thereafter. Moreover, the α-helix content decreased and the random coil content increased noticeably at 12 V·cm⁻¹. In terms of the properties of the SPI films, the mechanical properties and water resistance of the OH-SPI films were superior to those of the CON-SPI films. When the electric field was 9 V·cm⁻¹, the tensile strength of the OH-SPI film increased from 2.76 MPa to 4.34 MPa, and the elongation at break of the OH-SPI films improved. Moreover, the water resistance of the OH-SPI films was the best at this electric field.     

Synergistic effects of combinatorial Lactiplantibacillus plantarum fermentation and vegetable oils supplementation on the lycopene level,antioxidant capacities and flavor volatiles of tomato pulp

The objective of this study was to investigate the effects of Lactiplantibacillus plantarum (L. plantarum) fermentation and three types of vegetable oils (corn oil, peanut oil, and olive oil) supplementations on the physicochemical properties, bioactive components, and flavor volatiles of tomato pulp. Tomato pulp supplemented with oils was excellent food matrices for L. plantarum growth, and the colony counts remained above 8.3 log CFU/mL at the end of fermentation. The contents of total phenol, carotenoids and lycopene were dramatically increased after fermentation, and oils supplementation exhibited a synergistic promotion effect, especially for the combination of L. plantarum fermentation and 3% olive oil supplementation exhibiting the highest lycopene level (30 mg/mL), the strongest DPPH radical scavenging activity (84.24%) and FRAP (16.45 mmol Trolox/L). Furthermore, synergistic L. plantarum fermentation and oils supplementation decreased aldehydes content, and increased alcohols, esters, and ketones formation, meaning the improved flavor characteristics of fermented tomato pulp.Industrial relevanceIn this study, a functional beverage of tomato pulp was prepared by the combination of L. plantarum fermentation and vegetable oils supplementation. Colony counts, lycopene level, antioxidant capacities, and flavor characteristics were dramatically improved at the end of fermentation. This study provides an innovative technology to improve the release of lycopene from plant tissue and provide a functional beverage of tomato pulp with high health benefits.     

Study on the preparation of Ni–La–Ce oxide catalyst for steam reforming of ethanol

Two schemes for design and preparation of Ni–La–Ce oxide catalysts for steam reforming of ethanol were proposed in this work. The one via citrate complexing method was designed as NiO supported on ceria-lanthanum oxide (CL) solid solution, in which the strong interaction between NiO and CL solid solution was beneficial to inhibit the aggregation of NiO particles, and the abundant of oxygen vacancies existed in CL solid solution was in favor of carbon elimination from catalyst surface. The other was schemed as LaNiO₃ with perovskite structure loaded on CeO₂ support by using impregnation method, in which the particles of metal Ni derived from reduction of LaNiO₃ were highly dispersed, and the formation of La₂O₂CO₃ in the reaction process could act as the carbon scavenger. Both of the catalysts exhibited very good performance for steam reforming of ethanol (SRE), complete C₂H₅OH conversion was obtained with 70.3% of H₂ selectivity at 400 °C over the catalyst obtained from former method and complete C₂H₅OH conversion was achieved at 450 °C with 67% of H₂ selectivity over the catalyst from latter method. The catalyst made according to the citrate complexing method was more active for SRE and more selective for H₂ production. Both of the catalysts displayed very good anti-sintering ability which was tested at 650 °C and at a high space velocity of 180,000 ml g_cat⁻¹ h⁻¹ with reaction mixture of H₂O/C₂H₅OH = 3 in mole ratio. The results indicated that both of oxygen vacancy and La₂O₂CO₃ possessed the ability to remove the deposited carbon, and compared with La₂O₂CO₃ the oxygen vacancy could reduce one third more of the carbon deposited according to TG tests.     

环丙沙星、恩诺沙星、磺胺二甲嘧啶串联单链抗体的制备及融合表达产物抗原特性的分析

目的建立免疫学快速检测动物制品中的环丙沙星、恩诺沙星、磺胺二甲嘧啶残留,制备融合表达蛋白并进行评价。方法利用传统单克隆抗体制备方法分别制备环丙沙星、恩诺沙星、磺胺二甲嘧啶的单克隆抗体,通过聚合酶链式反应(polymerasechainreaction,PCR)获得3种单抗的单链抗体(single-chainvariable fragment,Sc-Fv),再通过套嵌PCR方法,使用柔性氨基酸Linker将已获得的单链抗体进行串联并通过分子生物学技术获得高效融合表达,以纯化的多联融合单链抗体为探针,结合前期技术建立的免疫学快速检测技术,对融合表达产物的抗原特性进行初步的分析。结果制备的单克隆抗体抗原抗体反应性良好,效价较高,融合表达抗体蛋白能够很好的与3种相应药物反应。结论本研究初步建立了特异性较高的3种药物的融合表达抗体的制备方法,且该抗体具有良好的反应原性。     

Procyanidins: extraction and micro‐ encapsulation

As by‐products of grape juice and wine production, grape seeds are a rich source of procyanidins but are usually discarded as waste. We have treated grape seeds with supercritical fluid extraction to remove the oils and have extracted the procyanidins from the residues. In order to extend the shelf life, micro‐encapsulating methods for procyanidins were studied: the use of gum arabic and maltodextrin as wall materials (the contents of arabic gum and maltodextrin were 40% and 60%, respectively). The raw materials were then mixed (the ratio of core substance to wall material was 30:70 w/w and the content of the slurry was 20% w/v). After homogenisation, spray drying was used to prepare microcapsules. The micro‐encapsulation efficiency was up to 88.84%. Analysis of the product showed that the procyanidin was not changed during the processing and the procyanidin microcapsule membrane was uninterrupted and with fairly good integrity. The stability of the products was also obviously improved. Copyright © 2007 Society of Chemical Industry     

多粘菌素B抑制丝状真菌的定量测定方法研究

为规范抗菌肽抑制丝状真菌的活力评价方法,采用多粘菌素B为抗菌肽研究对象,以黑曲霉(Aspergillus niger ATCC 16404)和产黄青霉(Pencillinm chrysogenum ATCC 10106)为指示菌,选用察氏培养基(20 mL培养基/90 mm平板)比较孢子萌发抑制法和菌丝生长抑制法,获得适合丝状真菌的测定方法,并进一步研究该方法的最适测定条件。结果表明,菌丝生长抑制法更适用于多粘菌素B抑制2株丝状真菌的定量检测。其中多粘菌素B抑制Aspergillus niger ATCC 16404的最适条件:指示菌培养48 h,接种菌饼直径(8.00±0.02) mm,在此条件下,测得多粘菌素B的EC₅₀为0.68 mg/mL;多粘菌素B抑制Pencillinm chrysogenum ATCC 10106的适宜条件:指示菌培养72 h,接种菌饼直径(5.80±0.02) mm,此时多粘菌素B的EC₅₀为0.45 mg/mL。本研究建立的抗菌肽抑制丝状真菌的活力测定方法具有普遍适用性,可为抗菌肽活性测定方法的规范及评价标准的建立奠定基础。     

Single-plasmid systems based on CRISPR-Cas9 for gene editing in Lactococcus lactis

Lactococcus lactis is a food-grade lactic acid bacterial species that is widely used in food and medical industries. Due to its relatively small genome and simple metabolism, L. lactis is commonly engineered to produce large quantities of recombinant proteins. The most common single-gene knockout strategy in L. lactis involves RecA-dependent homologous double-crossover recombination, which is relatively time-consuming and laborious. In this study, a precise and efficient genome-editing plasmid for L. lactis NZ9000 genome engineering, pLL, was established based on clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 technology. By studying the effects of different single guide RNA (sgRNA) promoters, the efficiency of gene deletion was optimized. For LLNZ_02045 (ldh), gene deletion efficiency of up to 50% was achieved. Effective sequential gene deletion of LLNZ_11240 (upp) and LLNZ_04580 (upp1) was also demonstrated using this tool. Additionally, the gene that encodes for uracil phosphoribosyltransferase was identified using this system. Similar robust gene deletion efficiencies of sgRNA that targeted different regions of a single gene suggested that gene deletion was not affected by the location of sgRNA binding. Thus, our study established a new gene-editing tool that may allow further investigation and understanding of the L. lactis NZ9000 genome.