The selective effect of food-grade guar gum on chalcopyrite-monoclinic pyrrhotite separation using mixed aerofloat(CSU11) as collector

The flotation separation of chalcopyrite from monoclinic pyrrhotite using food-grade guar gum(FGG) as a depressant was studied through flotation tests, kinetic studies, dynamic potential measurements, adsorption experiments, and infrared spectral analyses. The microflotation results showed that the flotation separation of chalcopyrite from monoclinic pyrrhotite could not be realized by adding mixed aerofloat(CSU11) alone. The depressant FGG exhibited a selective depression effect on monoclinic pyrrhotite by controlling the pulp pH range from 5.0 to 6.0, with a maximum floatability variation of 79.36% in the presence of CSU11. The flotation kinetics, zeta-potential, adsorption, and infrared spectroscopy studies revealed that the FGG could absorb more strongly on the surface of monoclinic pyrrhotite than on the surface of chalcopyrite. In addition, the results revealed that the interaction of FGG with the monoclinic pyrrhotite surface was governed primarily by strong chemisorption, whereas FGG mainly bonded to chalcopyrite through hydrogen bonding. This difference was responsible for the excellent depression selectivity of FGG toward monoclinic pyrrhotite flotation and weak depression effect toward chalcopyrite flotation.

The Study of Food-Grade Induced Expression and Enzymatic Properties of L-Arabinose Isomerase from Lactobacillus plantarum WU14 with High D-Tagatose Yield

L-arabinose isomerase (L-AI) is the key enzyme for D-galactose isomerization of D-tagatose by biological method. In this research, Lactobacillus plantarum WU14 with high D-tagatose yield was identified as Lactobacillus plantarum was isolated from the number of lactic acid bacteria from pickled vegetables. The crude L-arabinose isomerase activity of Lactobacillus plantarum WU14 with high D-tagatose yield was 13.95 U/mL under the optimal temperature 60&degC, pH 7.17 and substrate concentration 0.8 mol/L, and the conversion rate of 56.12% could be gained after 28 hours. Protein structure and specific of L-Arabinose Isomerase of Lactobacillus plantarum WU14 were researched. The results showed that L-arabinose isomerase is mainly composed of alpha helix and random coil. Then the recombinant L-AI gene was inserted into the food-grade expression vector pRNA48 and expressed in L. lactis NZ9000 successfully. The target protein expression reached the maximum amount when the induced concentration of nisin reaches 30 ng/mL after 12 h. And the crude enzyme activity of recombinant bacteria reached 6.21 U/mL under 60&degC. Otherwise the optimal conversion rate recombinant of L. lactis NZ9000/pRNA48-L-AI can reach 39.21% under the temperature of 50&degC, pH 7.17 and D-galactose concentration was 0.6 mol/L.

Construction of a Food-Grade Expression Vector Based on pMG36e by Using an α-Galactosidase Gene as a Selectable Marker

Construction of a food-grade expression vector for application to lactic acid bacteria（LAB） is of importance for dairy fermentation system. An α-galactosidase（aga） gene encoding an enzyme degrading melibiose was amplified by PCR from the plasmid p RAF800 of Lactococcus lactis NZ9000. The aga gene was introduced into pMG36 e to substitute the p rimary antibiotic selectable marker of pMG36 e, resulting in construction of a new food-grade expression vector pMG36-aga. To testify the expression efficiency of exogenous gene in pMG36-aga, a 1.5 kb long α-amylase（amy） gene from Ba cillus li cheniformis was cloned by PCR and introduced into the plasmid pMG36-aga. The resultant plasimd pMG36-aga-amy was transformed into L. lactis ML23 by electroporation. The positive clones were selected with the medium containing melibiose as the sole carbon source. Th e selection efficiency of aga was 8.71×103 CFU with a standard deviation of 9.1×102 CFU ？g-1 DNA of pMG36-aga. Furthermore, the SDS-PAGE analysis showed that the pMG36-aga-amy expressed a 56.4 kDa protein which was the same as the putati ve molecular weight of α-amylase. The starch plate assay also indicated that L. lactis ML23 displayed high activity of α-amylase by expressing of amy gene of pMG36-aga-amy.

Process development for producing a food-grade glucose solution from rice straws

In this paper, processes for producing a food-grade glucose solution through enzymatic hydrolysis of celluloserich solids obtained from rice straws are presented. The rice straws were pretreated by acid-catalyzed steam explosion, and the reaction efficiency, toxicity control, and process economic feasibility were studied. Mass transfer resistance to the hydrolysis reaction was reduced by grinding with glass beads. A higher glucose concentration could be obtained by feeding more cellulose in the hydrolysis reaction; however, this also resulted in the production of undesired byproducts. Thus, a soaking process for the cellulose solids in water was developed to effectively reduce the generation of byproducts in the hydrolysis reaction. The resulting food-grade glucose solution can provide 414 kilocalories per liter, and could be used during a food-shortage crisis in the future.The current production cost is estimated to be 0.82 USD·L^(-1).

Optimization of compression formulation and load of food-grade tracers for grain traceability using central composite design

Food-grade tracers have been developed as an identification technology for grain traceability from original harvest to final destination for transportation.The characteristics of food-grade tracers must be able to satisfy the environmental demands for grain traceability.To optimize the food-grade tracer production process,the effects of direct compression formulation and load on the mechanical characteristics were studied using response surface methodology(RSM)with central composite design(CCD).Among the four tested formulations,Formulations#2(consisting of 35.00%lactose 100 mesh,64.50%microcrystalline cellulose 102 and 0.50%magnesium stearate)and#4(consisting of 38.00%lactose 100 mesh,50.00%microcrystalline cellulose 102,11.00%pregelatinized starch and 1.00%magnesium stearate)were selected for tracer production based on their physical properties as powders.The value of Carr’s flowability index was 68 for both Formulations#2 and#4,which was the highest among all the formulations.Therefore,Formulations#2 and#4 also had the best powder flowability.The magnesium stearate ratio(1.00%-3.00%)and pressure(6.00-16.00 kgf)were used as independent variables to detect changes in the breaking rate,peak shear force and friction coefficient of tracers compressed by the selected formulations.The optimal production parameters could be achieved at a magnesium stearate ratio of 2.25%and pressure of 16.00 kgf for Formulation#2 and at a magnesium stearate ratio of 1.02%and pressure of 16.00 kgf for Formulation#4.Under these optimal conditions,the tracers had good impact characteristics(breaking rate),compression characteristics(peak shear force)and frictional characteristics(friction coefficient).Moreover,Formulation#2 was more suitable for production because compared to Formulation#4,its breaking rate and friction coefficient values were lower,and its peak shear force value was higher.

Optimization of tracer coating parameters and their effects on the mechanical properties and quality of food-grade tracers for grain traceability

The purpose of this study was to optimize the coating process of food-grade tracers to manufacture tracers with good physical,mechanical and practical properties and an excellent appearance.The effects of the coating weight gain(1.00%-5.00%),coating solution spray rate(1.50-7.50 g/min)and tablet bed temperature(30℃-40℃)on the coating appearance quality,moisture absorption rate,friction coefficient,peak shear force,breaking rate,barcode recognition rate,transport wear rate and transport recognition rate were analysed using a Box-Behnken design(BBD)of response surface methodology(RSM).The experimental data were fitted to quadratic polynomial models by multiple regression analysis.The mathematical models of the barcode recognition rate,transport wear rate and transport recognition rate exhibited no statistically significant difference in these data.The optimum coating parameters were as follows:a 5.00%coating weight gain,spray rate of 5.47 g/min and tablet bed temperature of 35.42℃.Under the optimized conditions,the tracers had a good appearance(coating appearance quality),moisture resistance(moisture absorption rate),and frictional(friction coefficient),compression(peak shear force),and impact characteristics(breaking rate).

A food-grade industrial arming yeast expressing β-1,3-1,4-glucanase with enhanced thermal stability

The aim of this work was to construct a novel food-grade industrial arming yeast displaying β-1,3-1,4-glucanase and to evaluate the thermal stability of the glucanase for practical application. For this purpose, a bi-directional vector containing galactokinase (GAL1) and phosphoglycerate kinase 1 (PGK1) promoters in different orientations was constructed. The β-1,3-1,4-glucanase gene from Bacillus subtilis was fused to α-agglutinin and expressed under the control of the GAL1 promoter. α-galactosidase induced by the constitutive PGK1 promoter was used as a food-grade selection marker. The feasibility of the α-galactosidase marker was confirmed by the growth of transformants harboring the constructed vector on a medium containing melibiose as a sole carbon source, and by the clear halo around the transformants in Congo-red plates owing to the expression of β-1,3-1,4-glucanase. The analysis of β-1,3-1,4-glucanase activity in cell pellets and in the supernatant of the recombinant yeast strain revealed that β-1,3-1,4-glucanase was successfully displayed on the cell surface of the yeast. The displayed β-1,3-1,4-glucanase activity in the recombinant yeast cells increased immediately after the addition of galactose and reached 45.1 U/ml after 32-h induction. The thermal stability of β-1,3-1,4-glucanase displayed in the recombinant yeast cells was enhanced compared with the free enzyme. These results suggest that the constructed food-grade yeast has the potential to improve the brewing properties of beer.

Phase behavior of supercritical CO_(2) microemulsion with food-grade surfactant AOT

Phase behavior of scCO2 microemul- sion formed with food grade surfactant sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) was studied Critical microemulsion concentration (cμc) was de- duced from the dependence of pressure of cloud points on the concentration of surfactant AOT at con- stant temperature and water concentration. The re- sults show that there are transition points on the cloud point curve in a very narrow range of concen- tration of surfactant AOT. The transition points were changed with the temperature and water concentra- tion. These phenomena show that lower temperature is suitable to forming microemulsion droplet and the microemulsion with high water concentration is likely to absorb more surfactants to structure the interface.

基于pyrF的乳酸乳球菌食品级表达载体的构建

基于pyrF筛选标记和来源于乳酸乳球菌(Lactococcus lactis,L.lactis)的基因组DNA为表达元件,构建L.lactis食品级表达载体,用于食品和药用多肽的表达和生产。首先,利用NZ3900 pyrF基因列构建同源重组突变盒,构建NZ3900 ΔpyrF突变株;然后,分别以来源于L.lactis的repA和repC基因为复制元件、pyrF基因为筛选标记、P_(32)和P_(8)为启动子、以及Tusp_(45)和TpepN为终止子,构建食品级表达质粒pLD;最后以绿色荧光蛋白ZsGreen为报告基因,验证ZsGreen在NZ3900 ΔpyrF突变株的表达及pLD-ZsG的遗传稳定性。实验结果表明,原养型ZsGreen阳性转化子可在普通Elliker培养基中正常生长,在荧光显微镜下观察到明显的绿色荧光信号;此外,PCR和Western blotting也证实ZsGreen能在NZ3900中表达且能稳定传代至30代,说明pLD食品级表达载体构建成功且使得外源蛋白在L.lactis中稳定表达。综上所述,基于pyrF营养缺陷型标记构建的L.lactis食品级表达载体的方法切实可行,可为推动L.lactis在食品和药用多肽生产中的应用提供研究基础。

食品薄膜封窖在酱香型白酒生产中的应用研究

酱香型白酒生产中的传统封窖方式不仅工作效率低下、末端处理成本较高,且因使用的窖泥为资源匮乏的本地紫红泥,大量使用不利于生态环境保护。为实现企业的可持续发展,通过使用食品薄膜替代部分窖泥,并优化封窖操作流程,以达到减少窖泥使用量的同时提高工作效率和节约成本的目的。本文简述了食品薄膜封窖和窖泥封窖的操作流程差异,并对食品薄膜封窖在酱香型白酒生产中的应用进行试验研究,对食品薄膜和窖泥封窖两种方式的基酒产质量、出窖窖面糟醅理化指标、出窖窖面糟醅微生物指标、基酒骨架成分含量、相关食品安全指标、工作效率及成本等进行对比分析。结果表明,两种封窖方式的基酒质量、出窖窖面糟醅理化、出窖窖面糟醅微生物指标上无明显差异,基酒骨架成分含量相似度较高,相关食品安全指标均符合国家标准,食品薄膜封窖相较于窖泥封窖工作效率提高了41.67%、总成本相差不大、窖泥使用量减少66.67%。综合分析后判断出食品薄膜封窖在酱香型白酒生产中的应用具有可行性。

中国食品级润滑油发展现状及前景展望

作为食品行业重要的配套产品,食品级润滑油对保障食品安全具有不可替代的重要作用。该文对食品级润滑油的产品特性、分类、认证标准、使用现状等进行分析,并结合中国食品级润滑油的发展现状,指出食品级润滑油发展面临的机遇与挑战。

食品级钛白粉的工艺创新研究

食品级钛白粉常作为食品增白剂使用,主要作用是提高食品的光泽度和白度。食品级钛白粉对重金属和杂质含量要求严苛,需要在现有的金红石型钛白粉生产工艺基础上做出针对性的改变。文章主要从配矿、二洗、砂磨、干燥等工序上进行食品级钛白粉的工艺创新研究,探讨食品级钛白粉的工艺改进路径。

茶多酚-淀粉纳米颗粒稳定Pickering乳液的特性

在蜡质玉米淀粉糊化过程中添加茶多酚(tea polyphenols,TP),并采用乙醇沉淀法制备纳米颗粒用于稳定食品级Pickering乳液。通过考察添加TP后淀粉纳米颗粒(starch nanoparticles,SNP)的结构性质、颗粒性质和乳化特性,探究其对Pickering乳液物理稳定性和氧化稳定性的影响。结果表明,TP与淀粉的羟基通过氢键发生相互作用;添加TP导致SNP的粒径由187.00 nm增加至233.80 nm,接触角由53.41°增加至80.60°,Zeta电位绝对值由|-17.20|mV增加至|-22.10|mV;利用TP-SNP稳定的Pickering乳液形成了大量的小乳滴;通过激光共聚焦扫描显微镜观察发现,TP-SNP能吸附在油水界面,形成一层物理屏障,抑制油滴聚结;通过检测Pickering乳液在15 d贮藏期油脂氧化产物的生成量,发现TP-SNP具有延缓乳液油脂氧化的作用,说明TP-SNP可以作为一种具有抗氧化功能的食品级颗粒乳化剂稳定Pickering乳液。

海阳市绿色食品(A级)网纹甜瓜生产技术规程

海阳市地处山东半岛南部,自然条件适宜甜瓜的生长,目前备受市场青睐的品种是网纹瓜‘鲁厚甜1号’。本文分析了‘鲁厚甜1号’的绿色食品级(A级)生产技术规程,从种子消毒、催芽、育苗、定植、生长期管理、病虫草害防治及采收管理等方面详细阐述绿色食品网纹甜瓜的生产技术,以期为实现其绿色高质生产提供技术标准。

石灰石制备食品级球霰石碳酸钙微球及其机理研究

以石灰石为原料,利用HNO3酸解和Ca(OH)_(2)沉淀除杂精制得到Ca(NO_(3))_(2)溶液,在氨氛围下采用CO_(2)碳化法制备食品级球霰石型碳酸钙。探讨了碳化工艺参数对碳酸钙晶型调控的影响,并利用扫描电子显微镜、X射线衍射仪以及傅里叶变换红外光谱仪对产物进行表征,提出了NH_(4)^(+)和NH_(2)COO^(-)共同作用调控球霰石晶型生成的机理。结果表明,氨氛围有助于球霰石的稳定成核。当NH_(3)·H_(2)O浓度为13%(质量分数)、CO_(2)流量为0.5 L/min、反应温度为25℃、反应时间为25 min时,制得2~5μm的单一相球霰石碳酸钙微球,产物的纯度达到99.5%(质量分数),质量符合《食品安全国家标准食品添加剂碳酸钙》要求。本研究可为石灰石的高值化利用和亚稳态球霰石型碳酸钙的制备提供理论基础。

A级绿色食品茭白生产用药梳理及建议

茭白为区域特色小宗作物,目前尚未有标准化的绿色食品生产指导规程。本研究根据《绿色食品农药使用准则》(NY/T 393—2020)对A级绿色食品农药使用范围的规定,梳理出茭白已登记的绿色食品可用农药清单,包括36种农药,可直接用于实际生产。同时,本文通过查阅相关文献,梳理出田间防效好的A级绿色食品允许用药清单,包括16种农药,以期为实际生产中农药登记作物范围的拓展提供参考。

高酶活性β-甘露聚糖酶定向进化及其用于制备甘露寡糖

为了提高β-甘露聚糖酶的活性,采用易错PCR将来源于地衣芽孢杆菌(Bacillus licheniformis)KD-1的β-甘露聚糖酶基因manBl进行定向进化,并在枯草芽孢杆菌(B.subtilis)中进行表达,以筛选酶活性提高的β-甘露聚糖酶突变体。筛选得到的突变体ManBl(I91N/L211I),其比酶活性为15554.7 U/mg,是野生型ManBl的4.1倍,食品级表达的胞外酶产量达17601.3U/mL。分子动力学和分子对接结果表明,β-甘露聚糖酶在2个位点(I91N/L211I)的突变,导致蛋白催化口袋柔性增加,与底物结合能力提高,进而提高了酶的催化效率。β-甘露聚糖酶ManBl(I91N/L211I)水解魔芋胶产物主要由甘露六糖、甘露三糖和甘露二糖组成。报道的I91N/L211I 2个位点联合突变能够提高β-甘露聚糖酶活性;ManBl(I91N/L211I)食品级表达为该酶的绿色安全应用奠定了基础。

食品级微生物发酵中药研究进展

食品级微生物发酵中药是对传统中药炮制的传承和发展。中药经食品级微生物发酵后有效成分提取率提高、药效增强、毒副作用降低,还具有改善口感、节约资源等优势,在养殖、医疗保健、化妆品等领域拥有广阔的研究和应用前景。本文综述食品级微生物发酵中药相关研究进展,主要从发酵技术、菌种选育和药食同源性中药的角度分析发酵对其协同效应、口感等产生的影响,并总结在不同领域的应用,为后续中药的研发提供参考。

食品安全背景下食品级铝合金表面处理技术研究

铝合金具有易于加工、耐腐蚀强、导热性能好等优点,在我国食品机械及包装行业具有广泛的应用。但如果铝合金表面技术处理不当,没能达到国家要求的食品级标准,长期使用就会存在机械腐蚀、重金属迁移等风险。本文介绍了铝合金制品在食品中的应用领域,分析其在食品机械及包装行业存在的潜在安全风险,论述了电镀及化学镀技术、微弧氧化技术等表面处理技术的优缺点。

特殊食品用脂肪粉对断奶仔猪生长性能、养分消化率和肠道菌群的影响

试验旨在研究特殊食品用脂肪粉对断奶仔猪生长性能、养分消化率和肠道菌群的影响,选取同批次23日龄左右健康“杜×长×大”三元杂交断奶仔猪360头,按照体重、日龄等相近原则分为4组(对照组和试验Ⅰ~Ⅲ组),每组6个重复,每个重复15头仔猪。对照组饲喂基础日粮,试验组用5%、10%和15%的特殊食品用脂肪粉等能等氮替代相应比例的原料。结果表明:与对照组比,试验组仔猪的试验末重、日均增重和日均采食量显著提高(P<0.05),腹泻率显著降低(P<0.05),料重比均有所降低,但差异不显著(P>0.05),试验组日粮干物质、粗脂肪、粗蛋白、钙和磷的消化率均显著高于对照组(P<0.05),所有肠段中,乳酸杆菌数量显著提高(P<0.05),大肠杆菌数显著性降低(P<0.05)。结果提示:断奶仔猪日粮中添加特殊食品用脂肪粉可明显提高断奶仔猪生产性能和养分消化率,促进肠道菌群稳定,明显降低腹泻率。