聚醚酯的热氧化和抗热氧化

本文讨论了各类抗氧化剂对共聚醚酯热氧化稳定性的影响。经测试分析，确定了各类抗氧化剂抑制共聚醚酯热氧化降解的规律，证实了它们之间的协同效应。     

食品抗氧化剂及其进展(三)

４主要抗氧化剂和抗氧增效剂按中国规定可允许使用的各种抗氧化剂及其基本情况参见表５。４．ＢＨＡ（叔丁基羟基茴香醚）ＢＨＡ是由２－叔丁基羟基茴香醚（简称２—ＢＨＡ）和３－叔丁基羟基茴香醚（３－ＢＨＡ）两种异构体以９：１的比例混合而成混合体。ＢＨＡ有一个活性羟基,因此只能提供一个氢。ＢＨＡ［Ｉ］经脱氢而成为ＡＯ自由基,再经自由基重排和偶合作用后,获得两种双酚二聚体［１１］和［６］：曾做过这样试验［７］ＢＨＡ的苯或大豆油溶液用紫外线照射后,这三种物质的变化情况见图５。可以看出,随着２－ＢＨＡ含量逐渐减少…     

氨基乙酸二硫代甲酸钴与稀土醋酸盐配合物的合成研究

在丙酮—水溶液中，用稀土醋酸盐与氨基乙酸二硫代甲酸钴［Ｈ６Ｃｏ２（Ｇｃ）５·ＣＳ２］反应，制备出十种稀土元素的多极配合物二通过元素分析和红外光谱分析确定了配合物组成为［ＲＥ２Ｃｏ２·（Ｇｃ）５·ＨＡＣ·ＣＳ２·ＸＨ２Ｏ］．ＲＥ＝Ｌａ～Ｌｕ，Ｙ，而Ｃｅ，Ｐｍ，Ｐｒ，Ｈｏ，Ｔｍ和Ｙｂ等除外，Ｘ＝２，５，８，Ｇｃ＝－Ｓ２ＣＮＨＣＨ２ＣＯ２－．研究了配合物的溶解性，并用红外光谱和热谱分析对新配合物进行表征．     

OCC／ONC涨价在先，美国出口废纸紧随其后

［浆纸商务网讯］美国向亚洲出口的旧箱纸板（ＯＣＣ）和８号旧新闻纸（ＯＮＰ）３月份继续涨价,已达到连续１０个月涨价记录。东、西两岸出口各类废纸价格继续上扬。（东岸分类白切边除外）西岸涨幅最大,由于西岸比东岸运费每吨低２０美元,西岸出口ＯＣＣ卖方码头ＦＯＢ价为１３５～１４０美元／吨,比２月份价格上升１７．５０美元／吨,比１９９９年５月份价格上升１２９%。中国和韩国仍是ＯＣＣ和ＯＮＰ的主要买家。东岸价格上升７．５０美元／吨,达１１０～１２０美元／吨。东岸ＯＣＣ出口价比１９９９年５月份出口价上升１４２%。有消息…     

中国专利文摘

专利申请号９９１１７４１０公开号１２５８７７８专利名称一种新型造纸施胶沉淀剂及其制造方法文摘本发明涉及的新型施胶沉淀剂由包括有铝、铝的氧化物、无机酸铝的盐类及它的化合物（Ａ）和碱金属盐及其化合物或氧化物（Ｂ）聚合,或再与含硅化合物（Ｃ）复聚合而成以下通式的聚合物：［Ａｌ２（ＯＨ）ｎ（ＳＯ４）３－ｎｘＨ２Ｏ］ｍ（１）式中：ｎ＝３－５ｍ＝１－１０或［Ａｌ２Ｓｉ（ＯＨ）ｎ（ＳＯ４）３－ｎｘＨ２Ｏ］ｍ·（２）式中：１≤ｎ≤５ｍ≤１０或［Ａｌ２（ＯＨ）ｎ（ＳＯ４）３－ｎｘＨ２Ｏ］ｍ·［Ａｌ２Ｓｉ（ＯＨ）ｎ…     

文摘

文摘ＷＣ轧辊的ＣａＷＯ４皮膜形成技术［刊，日］／井泽胜等／／材料—１９９４，７（２）—４３５生产表面光滑的线材，多使用碳化钙（ＷＣ）轧辊，但由于使用条件的不同ＷＣ轧辊表面也产生粗糙状况而影响线材表面质量。日本住友金属公司研制出对ＷＣ轧辊表面涂ＣａＷＯ...     

山东省部分水果及制品中展青霉素污染调查分析

山东省部分水果及制品中展青霉素污染调查分析宋家玉，邢金川，林艺山东省卫生防疫站（２５００１４）吴南，王玉华中国预防医科院营养与食品卫生研究所（１０００５０）１９９Ｏ年２月至１９９３年５月我们用ＴＬＣ法￣［１］进行了苹果、山楂等制品中展青霉素（Ｐａｔｕ...     

造纸文摘

细叶桉 ＣＴＭＰ Ｈ２Ｏ２高白度漂白［刊］刘晏…／国际造纸．１９９９,１８（５）： ２２～２５ 对细叶桉ＣＴＭＰ进行了单段及两段Ｈ２Ｏ２漂白研究,确定了Ｈ２Ｏ２漂白适宜的工艺条件。ＡＤＶＡＮＴ ＯＣＳ在废纸脱墨生产线上的应用［刊］沈祖相…／国际造纸．１９９９,１８（５）：４７～５０ 介绍美国Ｂｌａｃｋ Ｃｌａｗｓｏｎ公司日处理１５０吨的废纸脱墨浆生产线的工艺情况,并具体分析了采用ＡＢＢ公司的Ａｄｖａｎｔ ＯＣＳ开发控制系统,作为废纸脱墨生产线的控制系统运行过程及情况。沸石在制浆造纸工业中的潜在应用［刊］…     

蓖麻油脱水反应宏观动力学

本文提出以ＮａＨＳＯ４为催化剂，蓖麻油脱水反应宏观动力学方程，脱水属一级反应，在１８０～２２０℃脱水反应区间，动力学方程式ｒ＝ｋｏｅｘｐ（Ｅ／ＲＴ）·［ＶＯＨ］，其中活化能Ｅ＝４３．３２ｋＪ／ｍｏｌ，频率因子ｋｏ＝６．４１×１０－２［ｍｉｎ］－１。为ＤＣＯ工业生产与设计提供理论依据。     

空间C[0,1]的一个新的Schauder基

引入了区间［０，１］上一个新的标准正交系｛ｇａｌｋ（ｔ）｝∞０，证明了它在［０，１］上是一致有界的且是空间Ｃ［０，１］的Ｓｃｈａｕｄｅｒ基，同时｛ｇａｌｋ（ｔ）｝∞０的Ｌｅｂｅｓｇｕｅ函数｛Ｌ（Ｇ）ｎ（ｔ）｝在［０，１］上也是一致有界的，且｛ｇａｌｋ（ｔ）｝∞０还是［０，１］上的一个收敛系。     

Thermal Stability of Total Lipids Extracted from Zlatibor Bacon

In this study, non-oxidative and oxidative thermogravimetric analysis was applied as a method for determining the thermal stability of the total lipids extracted from Zlatibor bacon in different phases of production (raw samples, 10th and 30th day of smoking and 30th day of storage). The activation energies of the thermal degradation and oxidation of the total lipids extracted from examined samples were determined. A moderate increase of the activation energy, as well as the other information gained from TG analyses, indicated that there were no significant oxidative changes in Zlatibor bacon lipids during the production and storing.     

Identification of degradation pathways and products of cyanidin-3-sophoroside exposed to pulsed electric field

Pulsed electric field (PEF) can induce the degradation of anthocyanins. In this study, the degradation products and postulated degradation mechanism and pathways of cyanidin-3-sophoroside (Cy-3-soph) by PEF were investigated using a combination of UV–vis spectra and HPLC-MS. Four isomers of quinonoid benzoyloxyphenylacetic acid esters resulting from the oxidative degradation of Cy-3-soph at pH 1.5 and 3.5 were detected in a model solution after PEF. The prevailing degradation pathway was different from thermal degradation. Cy-3-soph was degraded through a Baeyer–Villiger oxidation by the nucleophilic attack of hydrogen peroxide and then further oxidised by other oxidants, such as the hydroxyl free radical induced by the electrochemical reactions during PEF treatment. The thermal degradation pathways at pH 1.5 and 3.5 were also involved in the degradation of Cy-3-soph during PEF treatment.     

稳定剂及其在聚酯生产中的应用

聚酯生产中会发生热降解和热氧降解等副反应，聚酯合成中需加入稳定剂抑制副反应。概述了热稳定剂和抗氧剂在聚酯生产中的应用发展，阐述各种稳定剂、抗氧剂之间具有协同效应，生产中稳定剂和催化剂可组成催化稳定体系。     

Effect of Oxygen on Thermal Degradation of 5-Methyl-5,6,7,8-Tetrahydrofolic Acid

Previous studies of thermal degradation of folic acid have not given consistent rate expressions or activation energies. The present study employed a model system which eliminated oxygen mass transfer limitations to examine degradation as a result of heating. A pseudo first-order reaction rate constant (k_365.K) and an activation energy (E_a) for thermal degradation due to an oxidative mechanism were estimated to be 0.154 ± 0.044 min^?1 and 16.3 kcal/mol, respectively. In the presence of N₂, these parameters were estimated to be 0.094 ± 0.009 min^?1 and 23.3 kcal/mol, respectively. While elimination of oxygen will not ensure folic acid retention, the overall degradation rate will be reduced significantly.     

Kinetics of ascorbic acid degradation in potato blanching

Degradation kinetics of ascorbic acid was investigated on potato strips wrapped in aluminium foil and blanched for 5–60 min at different temperatures between 65°C and 100°C. The results confirmed that first order kinetics is adequate in describing the degradation reaction. The value of the rate constant was found to pass through a maximum at 85–90°C, indicating the inactivation of oxidative enzymes around these temperatures. Comparison of the degradation losses based on the present investigation with results on total loss of ascorbic acid during blanching reported in the literature showed that thermal degradation accounts for a considerable portion of the total loss.     

Study of chemical modifications and fungi degradation of thermally modified wood using DRIFT spectroscopy

A mild thermal treatment of wood leads to improved macroscopic properties (dimensional stabilization and resistance against fungal degradation). The chemical modifications induced by the thermal treatment were investigated by means of DRIFT spectroscopy on wood blocks in order to explain the new macroscopic properties on a molecular level. The formation of new ether linkage was observed in addition to the well-known acidic hydrolysis reactions of wood. Fungal attack was found to take place even after thermal degradation of pentosanes by a standard oxidative way. A competition between depolymerization and condensation reactions was observed.     

Influence of the chemical structure on the thermal degradation of the glucosinolates in broccoli sprouts

Glucosinolates are secondary plant metabolites occurring in Brassica vegetables. Food processing significantly reduces glucosinolate content, among other things due to thermal degradation. As there is only little information about thermal glucosinolate breakdown, the influence of the chemical structure as well as the influence of different pH to thermal degradation of individual glucosinolates was studied by analysing desulphoglucosinolates with HPLC-DAD. Thermal degradation was forced by heating broccoli sprouts at 130 °C in dry medium, whereas the influence of the pH was studied by cooking at 100 °C in aqueous medium. Within each group of glucosinolates differences in thermal degradation were revealed. Within the sulphur containing aliphatic glucosinolates the oxidative state of the sulphur atom as well as the side chain length influenced the reactivity. Among the indole glucosinolates great differences in stability were observed. A hydroxyl function in the side chain generally seems to destabilise glucosinolates. Glucosinolates were most stable towards thermal treatment in neutral and slightly acidic medium, whereas they degraded more rapidly in basic medium.     

The effect of cooking on the fatty acid composition of longissimus muscle from beef heifers fed rations designed to increase the concentration of conjugated linoleic acid in tissue

Longissimus dorsi (LD) muscle from 60 Charolais crossbred heifers, aged for 14 days was used to investigate the effect of cooking on the content of PUFA and CLA fatty acids. Animals were offered a control diet of grass silage and concentrates (CO) or rations designed to enhance the concentration of CLA in tissue, i.e. unsupplemented grazed pasture (G), sunflower-oil supplemented grazing (SFG) or linseed-oil oil supplemented grazing (LSG). The SFG diet was the most effective for increasing the concentration of CLA but also caused the highest n-6/n-3 fatty acid ratio. There were no changes in the relative distribution of fatty acids upon cooking (140°C for 30min) and this procedure can be recommended because it preserves the nutritional value of the meat. It is concluded that irrespective of the change in the fatty acid composition of LD due to alteration in the diet of the cattle, cooking did not cause thermal degradation of PUFA, or thermal degradation or oxidative synthesis of CLA.     

Study of chemical modifications and fungi degradation of thermally modified wood using DRIFT spectroscopy

A mild thermal treatment of wood leads to improved macroscopic properties (dimensional stabilization and resistance against fungal degradation). The chemical modifications induced by the thermal treatment were investigated by means of DRIFT spectroscopy on wood blocks in order to explain the new macroscopic properties on a molecular level. The formation of new ether linkage was observed in addition to the well-known acidic hydrolysis reactions of wood. Fungal attack was found to take place even after thermal degradation of pentosanes by a standard oxidative way. A competition between depolymerization and condensation reactions was observed.     

Assessment of the oxidative and hydrolytic degradation of the lipid fraction of mortadella by means of HPSEC analyses of polar compounds

The aim of this work was to use the HPSEC analysis of polar compounds to assess the level of oxidative and hydrolytic degradation of the lipid fraction of mortadella. The results indicated high primary oxidative degradation of the lipid fraction in the samples, with a mean value for oxidized triacylglycerols of 1.77%, and low secondary oxidation, with a mean value for triacylglycerol oligopolymers of 0.16%. In addition, in some cases, significant hydrolytic degradation was found. HPSEC analysis of polar compounds, to evaluate the level of oxidative and hydrolytic degradation of the mortadella lipid fraction, could be used as an alternative to commonly used techniques, some of which are not always reliable.