三个新品种桉木制浆造纸性能评价

桉树是一种速生树种,适宜造纸.雷州林业局是我国最早进行桉树人工林培育单位之一.本文对该林业局新培育的3个新品种的桉树进行了化学组成和纤维形态分析;并研究了它们的蒸煮和漂白性能,同时与原有品种进行了比较,结果显示,新品种桉树具有较好的制浆造纸性能.     

“九华佛茶”品牌建设的思考

2002年,池州市实施茶叶品牌整合战略,推出主打品牌——“九华佛茶”品牌。通过两年多的运营,“九华佛茶”品牌建设初见成效,但也暴露出一些问题,对此,本文从多方面进行分析,提出了一些具体对策。     

鲑鱼皮制革工艺的研究

前言随着淡水养殖的逐年增加和不断发展,淡水鱼的深加工也在迅速发展,作为副产品之一的鱼皮会越来越多,从而确保了鱼皮制革原料的稳定,鱼皮制革的长足发展势在必行。从皮革制品的市场分析,随着广大消费者对皮革制品认知程度的加深,鱼皮革制品的市场也越来越广阔。天然鲑鱼皮革的各项理化指标,均可达到同类型牛羊皮革制品的指标,而且以其轻软、薄透、结实耐用的特点,特别是人工难以模仿的独特自然花纹,而得到广大消费者的青睐。用鲑鱼革制成的箱包、票夹、皮鞋、服装饰品等都是高档消费品,除了具有实用价值以外,还具有艺术价值。作为一种新型…     

猕猴桃干酒超滤澄清技术研究

为避免猕猴桃干酒的后浑浊,提高其非生物稳定性,采用过滤分离的方法,对用中空纤维膜超滤澄清的猕猴桃干酒的工艺技术进行了研究。试验结果表明:超滤澄清猕猴桃干酒的最佳工艺参数为:干酒温度20～25℃,超滤压力0.04M Pa,猕猴桃干酒的流量6L/h,超滤时间17m in。用中空纤维超滤膜处理猕猴桃干酒,可降低能耗,缩短加工时间,改善产品质量。超滤能除去酒中大部分易引起沉淀、浑浊的蛋白质及酚类物质,干酒的色泽得到一定程度的改善,而对其营养成分和风味物质影响不大。超滤处理猕猴桃干酒是一种较理想的澄清方式,澄清效果显著。     

基于CZT的电力谐波参数高精度估计

提出了一种基于CZT的电力系统谐波参数高精度估计方法.利用CZT实现频谱细化的特点,首先从复杂信号中提取基波分量,将其减去.然后对剩余信号加5项Rife-Vincent窗,进行FFT分析.最后根据提取基波频率求出各次谐波频率,对Rife-Vincent窗函数在频域插值.仿真验证表明5项Rife-Vincent窗抑制频谱泄露效果很好,在非同步采样的情况下,对含有30次谐波的复杂信号进行仿真分析,结果与传统双谱线插值算法有几乎相同的估计精度,但计算时间约节省了一半.     

The impact of processing on phytic acid,in vitro soluble iron and Phy/Fe molar ratio of faba bean (Vicia faba L.)

BACKGROUND: Faba bean is one of the important legumes in Asian countries. It is also a major source of micronutrients in many rural areas. Unfortunately, the bioavailability of iron from faba bean is low because it is present as an insoluble complex with food components such as phytic acid. The influence of soaking, germination and fermentation with the expectation of increasing the bioavailability of iron was investigated. RESULTS: Fermentation treatments were most effective in decreasing phytic acid (48–84%), followed by soaking at 10 °C after preheating (36–51%). Steeping faba beans for 24 h at 25 °C had the least effect on the removal of phytic acid (9–24%). With increased germination time at 30 °C, phytic acid progressively decreased from 9 to 69%. Most wet processing procedures, except soaking after wet preheating, caused losses of dry matter and iron (8–15%). In vitro iron solubility, as a percentage of total iron in soaked faba bean after dry preheating, was significantly higher than in raw faba bean (P < 0.05). Fermentation and germination did not have significant effects on the solubility of iron. CONCLUSION: The expected improvement of iron bioavailability levels due to lower phytic acid was not confirmed by increasing levels of in vitro soluble iron. Soaking, germination and fermentation can decrease phytic acid in faba bean. However, results from in vitro solubility measurement of iron showed little improvement of iron bioavailability in fermented and germinated faba beans over untreated raw faba beans (P < 0.05). It seems that componets of dietary fibre other than phytic acid are more important in binding iron. Probably, a complex association between dietary fibre and iron is the reason for the poor bioavailability of iron in faba bean. Copyright © 2009 Society of Chemical Industry     

Bioeffects of chromium(III) on the growth of Spirulina platensis and its biotransformation

BACKGROUND: In this study the bioeffects of chromium(III) (Cr(III)) on the growth of Spirulina platensis and its biotransformation were investigated. Spirulina platensis was batch cultured in Zarrouk medium containing different concentrations of CrCl₃ · 6H₂O. Total and organic Cr contents in S. platensis were determined by inductively coupled plasma mass spectrometry (ICP‐MS), and Cr speciation was assayed by high‐performance liquid chromatography/ICP‐MS. RESULTS: Results based on the dry weight, growth curve, chlorophyll yield and morphology change of S. platensis indicated that the growth of S. platensis was facilitated by Cr(III) below 4.51 mol L^?1 and inhibited by a higher concentration of Cr(III). It was found that Cr(III) could be accumulated efficiently in S. platensis, with a highest Cr yield of 173.17 g kg^?1 and a highest organic Cr proportion of 50.19 g kg^?1 (96.04% of the total concentration of Cr). No evidence of oxidation of Cr(III) to Cr(VI) in S. platensis cells was found. CONCLUSION: The results of this study suggest that S. platensis could potentially be used as a safe food carrier to accumulate Cr(III) through some metabolic process. Copyright © 2009 Society of Chemical Industry     

Mass spectrometric detection of marker peptides in tryptic digests of gelatin: A new method to differentiate between bovine and porcine gelatin

Gelatin is a mixture of polypeptides obtained by hydrolysis of collagen primarily from bovine and porcine skin and bones. The similarity between different gelatins makes it difficult to trace their species origin. In this work, a new method for differentiation between bovine and porcine gelatin was developed based on detection and identification of marker peptides in digested gelatins. Sequence alignment analysis indicates that bovine and porcine Type I collagen contain differential sequences. The gelatins were digested by trypsin, and the resulting peptides were analyzed by high performance liquid chromatography/tandem mass spectrometry (HPLC–MS/MS). The marker peptides specific for bovine and porcine were successfully detected in the digested bovine and porcine gelatin, respectively. Comparative analysis indicated that more marker peptides could be detected in gelatin with a higher mean molecular weight. It was found that proline hydroxylation was a key factor affecting the peptide identification. For peptides such as GPPGSAGSPGK and GPPGSAGAPGK detected in digested bovine and porcine gelatin, respectively, the sequence should be verified manually since the mass shift caused by proline hydroxylation can be confused with the mass difference between Ser and Ala residues. The results indicate that detection of marker peptides in the digested gelatin sample using HPLC–MS/MS is an effective method to differentiate between bovine and porcine gelatin.     

中药渣及袋栽平菇中重金属含量的研究

用原子吸收分光光度法对药渣及用药渣栽种的平菇中重金属元素铅、铜、镉含量进行了测定,并用单项累积污染超标倍数Pe进行评价。结果表明:药渣中铜、铅、镉均被检出,铜的平均含量为14.32 mg/kg,镉的平均含量为0.212 5 mg/kg,均低于中国药典2005版和绿色行业标准的限量标准;铅平均含量为8.356 mg/kg,高于中国药典2005版和绿色行业标准1.67倍,其单项累积污染超标倍数Pe为0.67。用药渣栽种的平菇(试验组)中重金属铅、镉均未检出,说明平菇对药渣中的铅未产生富集现象,铜平均含量为9.199 mg/kg,低于国家食品(蔬菜、食用菌)卫生限量标准,平菇中铜、铅、镉含量是安全的。     

中国食品安全风险交流的现状、问题、挑战与对策

风险交流是中国食品安全体系中最薄弱的环节,随着食品安全风波不断,中国政府不断加大食品安全重点整治力度,落实政府监管职责.本文从政府、公众、媒体、风险交流学科等不同角度分析了中国食品安全风险交流的现状、问题与挑战,并针对性地提出了对策措施.