Multi-walled carbon nanotubes/nickel hydroxide composite applied as electrochemical sensor for folic acid (vitamin B9) in food samples

Folic acid (FA) acts as an essential nutrient for body functions. Several countries have already proposed a resolution for flour fortification with iron and FA; thus, of food industry concern. Therefore, a new electroanalytical method based on a composite material of functionalized MWCNTs with nickel hydroxide (f-MWCNT-Ni(OH)₂) is hereby proposed. This composite material was characterized by FT-IR, TGA, SEM and TEM techniques. An inorganic ionic silsesquioxane polymer (Si4Pic⁺Cl⁻) was used to disperse the composite and applied on the modification of a glassy carbon electrode (GCE). Linear response from 0.5–26 μmol L⁻¹ was obtained based on FA electrochemical oxidation through differential pulse voltammetry. The LoD and LoQ values obtained were 0.095 μmol L⁻¹ and 0.3 μmol L⁻¹ of FA, respectively. The GCE/f-MWCNT-Ni(OH)₂-Si4Pic⁺Cl⁻ was applied for the quantification of FA in wheat flour, fortifier, and dietary supplement. Validation was performed through a comparison with molecular absorption spectrometry, showing the accuracy of the newly proposed method.     

魔芋属三种食疗植物中的营养成分分析

<正> 魔芋食用、药用历史悠久,据中国植物志和本草考证结果,其原植物应为花魔芋(A.konjac)和疏毛魔芋(A.sinensis)。但近年刘佩瑛又将生产“金河芋角”的魔芋的原植物定为一个新种,即白魔     

计算机在制粉工艺动态参数监测中的应用

计算机应用于制粉工艺动态参数的监测，能及时准确地反映生产状况，指导操作与生产管理。通过企业生产运行，证明其监测系统性能稳定、数据准确、效果显著。     

魔芋精粉对五种二价金属离子的体外结合研究

本研究采用体外模拟体内胃肠道环境某些条件用透析方法研究了魔芋精粉与Ｐｂ＾２＋、Ｃｄ＾２＋、Ｆｅ＾２＋、Ｚｎ＾２＋、Ｃａ＾２＋的结合。并探讨了加热处理、ｐＨ改变及环境共存离子的竞争作用对结合的影响。结果表明，魔芋精粉与五种离子的结合具ｐＨ依赖性，ｐＨ５￣５．６时发生不同程度的结合，ｐＨ１．５时无结合，ｐＨ６．５时随离子浓度增加魔芋精粉与Ｐｂ＾２＋、Ｃｄ＾２＋的结合降低，与Ｃａ＾２＋的结合增加，与Ｚｎ     

胡芦巴胶对混合粉制面包及生面团品质的影响

去皮高粱粉和粟米粉作面包用粉的替代物，以不同比例添加使用。胡芦巴胶部分替代面粉，替代率可达０．９％，研究了胡芦巴胶对流变特征及面包品质的影响。添加胶越多，生面团吸水量亦越高；添加胡芦巴胶后，生面团的稳定时间、断裂时间和机械耐力指数均有提高。按４∶１的面粉／高粱粉配方，添加０．６％胶可增大面包体积２１．８％，而０．９％的胶添加量能增大面包体积２１．３８％．     

Bakers' exposure to flour dust

We aimed to characterize bakers' personal exposure to airborne flour dust with respect to the health-related aerosol fractions inhalable, extrathoracic, and thoracic dust, and to examine possible production-related determinants of dust exposure.

Sixty-eight bakers from 7 bakeries in Bergen, Norway (2009–2012) participated in the exposure assessment, comprising full-shift personal samples of inhalable dust (n = 107) and thoracic dust (n = 61). The relation between possible determinants and exposure was estimated using mixed effects models, while associations between the various aerosol fractions across task groups and type of bakeries were described by Pearson's correlation coefficients.

Bakers' overall geometric mean personal exposure to inhalable, extrathoracic, and thoracic dust were 2.6 mg/m³ (95% CI: 2.0, 3.2), 2.2 mg/m³ (95% CI: 1.9, 2.7), and 0.33 mg/m³ (95% CI 0.3, 0.4), respectively. A total of 29% of the measurements of inhalable dust were above the Norwegian Occupational Exposure Limit of 3 mg/m³. The exposure variability of inhalable dust could not be explained by any of the examined production-related determinants, while the daily production volume explained 18% of the variance in thoracic dust exposure. Overall, the thoracic dust represented 15% of the inhalable dust, being rather stable across the production-related determinants. The overall correlation between inhalable and thoracic dust was nevertheless moderate (r = 0.52, p < 0.001), with the highest correlation for craft bakers (r = 0.62) and no correlation during dough forming (r = 0.01).

Bakers are exposed to flour dust at a level that most likely represents an excess risk of developing chronic diseases of the respiratory system, and a decrease of present exposure level is imperative. Extrathoracic dust—likely the most relevant sub-fraction in respect to flour-induced sensitization and occupational rhinitis—represented the main proportion of the measured inhalable dust. The variation in correlation coefficients between the dust fractions across bakery types and task groups underlines the need of more knowledge about how these aerosol fractions are distributed across the production process and bakery types.     

Thiamin fortification of bread-making flour: Retention in bread and levels in Australian commercial fortified bread varieties

In Australia, thiamin is mandatorily added to bread-making flour with the main purpose of fortification and reducing the prevalence of Wernicke–Korsakoff syndrome. This study aims to measure the retention of added thiamin through laboratory-scale bread processing and provide an update on thiamin contents in commercially fortified bread and flatbread varieties since the introduction of the program in 1991. Even though baking caused degradation loss of thiamin (approximately 16%), the laboratory fortified white bread had a 25% higher thiamin content than its corresponding flour, and laboratory fortified wholemeal bread showed a 16% increase (p < 0.05). Thiamin levels in commercially fortified bread and flat bread varieties ranged between 0.24 and 1.9 mg/100 g (dry weight basis). It can be suggested that most of the bread varieties were made from flour fortified at the minimum mandated level (0.64 mg/100 g flour). Samples of flat bread varieties (white without yeast, wholemeal with yeast and wholemeal without yeast) showed low thiamin levels (0.24–0.49 mg/100 g, dry weight basis). The results suggest that the flat bread varieties were likely made from either commercially under-fortified flour or unfortified general-purpose flour, as only bread-making flour is fortified with thiamin.     

燕麦饼干的开发

以燕麦粉和特一粉为原料，按一定比例配粉制作酥性饼干，通过单因素试验和多因素正交试验，确定最佳配比，获得了比较满意的燕麦饼干制品。     

Influence of Stereochemistry on Relative Reactivities of Glucosyl and Mannosyl Residues in Konjac Glucomannan (KGM)

Methylation in water with NaOH/MeI is applied to study the influence of the stereochemistry on relative reactivities of d ‐mannosyl (M) compared to d ‐glucosyl (G) units in konjac glucomannan (KGM). The pH is kept constant at 13.6 over the course of the reaction and aliquots are removed after various time intervals. Methyl distribution in G and M residues is determined after perethylation, hydrolysis, and conversion to O‐ethyl‐O‐methyl‐alditol acetates. The order of relative rate constants determined for the O‐methyl Konjac glucomannans (M‐KGMs) in degree of substitution (DS) range 0.3–0.8 is G‐k ₆ > M‐k ₆ > G‐k ₂ ≈ M‐k ₂ > M‐k ₃ > G‐k ₃. Oligosaccharides obtained by partial hydrolysis after full protection of M‐KGM with MeI‐d ₃ are labeled with m‐amino‐benzoic acid and measured by liquid chromatography–electrospray ionization–mass spectrometry. DS/DP profiles are in full agreement with random distribution of methyl groups. Thermal properties of M‐KGMs are analyzed by differential scanning calorimetry and thermogravimetric analysis. Decomposition temperature increases with DS, while the temperature of an endothermic change decreases.

     

国产高效液相色谱仪测定面粉中过氧化苯甲酰

目的建立国产高效液相色谱仪测定面粉中过氧化苯甲酰的方法。方法高效液相色谱法。结果方法的精密度为(0.5-1.5)%,回收率为(95.3-104)%均能满足实验要求。以1.00 g样品进行测定的最低检出浓度为0.004 mg/kg,过氧化苯甲酰浓度在(0.002?0.01)mg/mL范围内相关系数r=0.999 8。结论该方法操作简便、快速、结果可靠,可在基层实验室推广使用。