不同抗氧化剂对降低豆奶中脂肪氧化酶活性的研究

用不同的抗氧化剂对豆奶中脂肪氧化酶活性的影响进行了比较，并对各种抗氧化剂进行了不同水平试验，实验表明，在没食子酸丙酯（PG），HBA，BHT，抗坏血酸（AA）中，PG对抑制豆奶中脂肪氧化酶活性方面效果更好，EDTA，柠檬酸（CA），AA与PG结合实验表明，PG中加入CA，AA，能够增强PG对脂肪氧化的抑制效果。     

不同抗氧化剂对降低豆奶中脂肪氧化酶活性的研究

对不同的抗氧化剂对豆奶中脂肪氧化酶的活性的影响进行了比较，并对各抗氧化剂进行了不同水平的试验，实验表明，在没食子酸丙酯(PG)、BHA、BHT、抗坏血酸(AA)中，PG对抑制豆奶中脂肪氧化酶活性方面效果更好。EDTA、柠檬酸(CA)、AA与PG结合实验表明，PG中加入CA、AA，能够增强PG对脂肪氧化酶的抑制效果。     

肉制品脂肪氧化抑制的研究

研究了几种抗氧化剂对肉制品（火腿肠）脂肪氧化的抑制作用，比较了这些抗氧化剂（添加剂）作用的相对强弱，通过实验及数据处理，认为没食子酸丙酯（ＰＧ）在肉制品中上较理想的抗脂肪氧化的功能，发现了大豆蛋白，含亚硝基亚铁血色原的色素也具有一定的抗脂肪氧化的能力。     

植酸及其他几种抗氧化剂抗氧化作用的研究──植酸及单一抗氧化剂抗氧化性能的研究（Ⅰ）

本文比较研究了在６０℃下植酸与其它几种抗氧化剂（ＶＥ、ＢＨＡ、ＢＨＴ、ＰＧ、ＴＢＨＱ）对不同种类油脂（猪油、精炼豆油和花生油）的抗氧化性能比较。     

酸性豆乳饮料稳定性的研究

本文叙述一种酸性豆乳饮料的制作方法，由于该饮料不确定而引起脂肪上浮和蛋白质沉淀，使产品外观和口感欠佳，针对此问题，对不同ＨＬＢ值的混合乳化剂和稳定剂的效果进行实验，结果表明：当混合乳化剂量为０．１％（其中单甘酯和蔗糖酯１：１）ＣＭＣ和ＰＧＡ各为０．２％时，大大增加饮料的稳定效果，达到预期目的。     

藻酸丙二醇酯粘度的研究

研究了食品增稠剂藻酸丙二醇酯（ＰＧＡ）的粘度特性。实验表明：ＰＧＡ的粘度与其浓度之间存在着半对数线性关系（Ｒ２＝０．９７４０）；在ｐＨ２～１０范围内，ＰＧＡ的粘度几乎无变化，但当ｐＨ≥１１时，ＰＧＡ的粘度下降；ＰＧＡ与羧甲基纤维素（ＣＭＣ）具有良好增粘效应，但与海藻酸钠之间的效应较复杂。     

乌骨鸡对延缓果蝇衰老作用的研究

本文分析比较了乌骨鸡和普通肉鸡的一般营养成分,并对乌骨鸡进行了延缓果蝇衰老的生物学实验。结果表明：（１）乌骨鸡肉中的微量元素Ｃｕ、Ｚｎ、Ｓｅ、Ｇｅ及维生素（ＶＢ１、ＶＢ２、ＶＢ５、ＶＥ）含量明显高于ＡＡ肉鸡,而其它成分含量相近。（２）乌骨鸡和普通肉鸡相比能显著延长果蝇的平均寿命（Ｐ〈０．０５）。但对最高寿命的延长作用不明显;乌骨鸡能提高果蝇的性活力,降低果蝇脂褐素含量（Ｐ〈０．０５）,表明乌骨鸡能     

薏苡仁的抗诱变性研究

应用Ａｍｅｓ试验方法，对薏苡仁的丙酮提取液进行抗诱变性研究。选用直接致突变物亚硝基胍（ＭＮＮＧ）和间接致突变物苯并（α）芘　　（Ｂ（α）Ｐ）为模型致突变物，进行诱导鼠伤寒沙门氏菌ＴＡ９８移码型、ＴＡ１００碱基置换型回复突变抑制作用实验。观察不同浓度薏苡仁丙酮提取液的抑制突变效果。结果表明：薏苡仁对ＭＮＮＧ和Ｂ（α）Ｐ诱导的鼠伤寒沙门氏菌ＴＡ９８、ＴＡ１００引起的回变菌落数随加入样品浓度增加而减少。经统计学分析呈显著性差异。提示：薏苡仁有抑制突变作用。该物作为防癌保健食品具有重要意义。     

三种食品抗氧化剂对核桃油抗氧化作用的影响

测定了目前国内外常用的三种食品抗氧化剂,２,６－二叔丁基对－甲酚（ＢＨＴ）、没食子酸丙酯（ＰＧ）、特丁基对苯酚（ＴＢＨＱ）对核桃油在保存过程中因过氧化而产生的哈变的抑制作用,结果表明,３０℃下经６０３h后,对照组的过氧化值最大值仅４６．１２,实验组过氧化值均低于此值,且以添加０．０２％ＴＢＨＱ组的过氧化值最低,仅为１６．５４,不同抗氧化剂组合实验显示,６０３h后,各实验组过氧化值均低于对照组,且以０．０１％ＰＧ＋０．０２％ＴＢＨＱ＋０．１５％柠檬酸组效果最好,过氧化值为８．５２,０．０２％ＢＨＴ＋０．０２％ＴＢＨＱ组和０．００５％ＢＨＴ＋０．００５％ＴＢＨＱ＋０．００５％ＢＨＴ组最差,因此０．０１％ＰＧ＋０．０２％ＴＢＨＱ＋０．１５％柠檬酸为核桃油抗氧化的最佳抗氧化剂。     

植酸及其它几种抗氧化剂抗氧化作用的研究──复合抗氧化剂的抗氧化性能研究（Ⅱ）

利用烘箱法及Ａ．Ｏ．Ｍ法，以几种食用油脂为测试对象，通过添加植酸溶液及植酸与几种抗氧化剂（ＶＥ、ＢＨＡ、ＢＨＴ、ＰＧ、ＴＢＨＱ）所构成的复合抗氧化剂，考察它们对油脂稳定性的影响，验证植酸的抗氧化增效作用。     

In vitro and in vivo antioxidant properties of ferulic acid: A comparative study with other natural oxidation inhibitors

Ferulic acid exhibits a wide range of therapeutic effects that are attributed to its potent antioxidant capacity. However, in vitro antioxidant properties of ferulic acid have not been elucidated in detail. Evidence that polyphenols, including ferulic acid, act as antioxidants in vivo is also limited. In order to elucidate in more detail the scientific background of antioxidant activities of ferulic acid, we carried out in vitro and in vivo experiments. We focused on superoxide anion scavenging activity, xanthine oxidase inhibition activity, and chain-breaking activity. The combined antioxidant activity from radical scavenging and xanthine oxidase inhibition of ferulic acid was much weaker than that of (−)-epigallocatechin gallate (EGCG) and ascorbic acid. On the other hand, EGCG, ascorbic acid and ferulic acid exhibited chain-breaking activity and prevented ischaemia-reperfusion-associated intestinal injury. Chain-breaking activity may play a contributory role in the protective effect of ferulic acid on oxidative injury in humans and in in vivo studies.     

Effect of preservation techniques and food additives on staphylococcal thermonuclease

Staphylococcal TNase was found to retain its activity fully even after exposure to chilling and refrigeration temperatures for 24 h. It was not inhibited by p-hydroxy benzoic acid, sorbic acid, methylpropyl p-benzoic acid and sodium nitrite in the concentration range of 0.04 to 0.5%, whereas it was inhibited by 100 ppm of butylated hydroxy anisole (BHA), 200 ppm of butylated hydroxy toluene (BHT), and 300 ppm of propyl gallate. There was not complete inhibition of S. aureus and TNase by tocopherol (TP) and ascorbic acid (AA) even at concentration of 300 ppm. These results indicate that TNase can be used as an index of potentially enterotoxin producing S. aureus contamination in foods subjected to chilling, refrigeration as well as in foods containing common preservatives and antioxidants.     

Purification of polyphenol oxidase and the browning control of litchi fruit by glutathione and citric acid

Polyphenol oxidase (PPO, EC 1.10.3.2) was purified to homogeneity from litchi peel yielding a single protein with a molecular weight of about 75.6 kD by Sephadex G‐100 gel filtration, and a 108‐fold purification of PPO achieved. The enzyme was determined to be composed of two similar subunits. Glutathione, L ‐cysteine and citric acid suppressed PPO activity markedly, whereas ascorbic acid and n‐propyl gallate showed a little inhibition. Moreover, the effect was enhanced by the addition of citric acid. On the basis of the inhibition of PPO activity in vitro, the use of 10 mmol l ⁻¹ glutathione and 100 mmol⁻¹ l citric acid was found to give good control of the browning of litchi fruit, and an 80–85% inhibition of PPO activity was observed. It is suggested that application of glutathione in combination with citric acid may slow down the browning of litchi fruit. © 1999 Society of Chemical Industry     

The effect of ascorbic acid,citric acid and low pH on the extraction of green tea: How to get most out of it

Green tea seems to have a positive impact on health due to the therein-found flavanols. The amounts of these substances depend on tea preparation. In this paper, the influence of steeping time (3–7 min) and temperature (70–100 °C) on the content of the main flavanols in green tea (epicatechin EC, epicatechin gallate ECg, epigallocatechin EGC, and epigallocatechin gallate EGCg) is presented. Furthermore, additives (phosphate buffers, ascorbic acid in different amounts, and citric acid) are used to investigate the influence of pH, antioxidative, and chelating agents, simulating the addition of lemon juice or pure vitamin C.     

DPPH antioxidant assay revisited

Scavenging of DPPH free radical is the basis of a common antioxidant assay. A number of protocols have been followed for this assay resulting in variation in the results of different laboratories. We present a perspective of the protocols followed by different workers with incongruity in their results and recommend a standard procedure within the sensitivity range of spectrophotometry. Three common standard antioxidants viz. ascorbic acid, BHT and propyl gallate have been used in this study. The IC₅₀ values for ascorbic acid and propyl gallate were 11.8 μM and 4.4 μM in methanol and 11.5 μM and 4.7 μM in buffered methanol as reaction medium, respectively. The free radical scavenging by BHT was markedly influenced by the reaction medium. The IC₅₀ values were 60.0 μM and 9.7 μM when the reaction was done in methanol and buffered methanol, respectively.     

Antioxidant and modified atmosphere packaging prevention of discoloration in pork bones during retail display

The objective of this study was to evaluate the ability of antioxidants to prevent discoloration in pork rib bones. Pork rib bones were removed from carcasses, frozen (−20 °C, 24 h), split lengthwise, exposed to antioxidant solutions (ascorbic acid, citric acid, propyl gallate or ascorbic/EDTA mix), packaged (modified atmosphere [80% O₂ and 20% CO₂] or air), then displayed in a retail case at 4 °C for 8 days. Dark pigment formation was visually evaluated during the display period. Instrumental color was determined at the end of the 8-day display period. Visual bone discoloration increased over time for all treatments. After 2 days of display, samples treated with propyl gallate were visually redder, less discolored and less green/black than samples treated with other antioxidants. After 8 days of display, propyl gallate-treated samples had higher a* and b* values, as well as chroma (intensity). However, this difference was no longer large enough to be visually detected.     

The ability of gallate and pyrogallol moieties of catechins to inhibit P-glycoprotein function

The role of structure–activity relationships in the ability of catechins to inhibit P-glycoprotein (P-gp) function was investigated with respect to gallate and pyrogallol moieties. Experiments using octyl derivatives of gallic acid indicated that the gallate moiety required the catechol group and a neighboring carbonyl group to inhibit P-gp. On the other hand, the pyrogallol moiety appeared to require three hydroxyl groups to inhibit P-gp, according to comparisons between (−)-epicatechin gallate (ECG) and (−)-epigallocatechin gallate (EGCG). The difference in the number of hydroxyl groups that gallate or pyrogallol moieties required for P-gp inhibition, was due to the presence of a carbonyl group. The P-gp inhibition by catechins was restricted by their hydrophobicity. The pyrogallol moiety of EGC did not appear to inhibit P-gp because of its low hydrophobicity. The P-gp inhibitory activity of EGCG was speculated to be increased by the addition of long carbon chains to the C3″of gallate moieties.     

橡子仁萃取物成分分析及对α-淀粉酶、α-葡萄糖苷酶的抑制作用

为探索橡子仁萃取物的成分组成及对α-淀粉酶、α-葡萄糖苷酶的抑制作用,以栓皮栎橡子仁为材料,采用超声波辅助乙醇提取和有机溶剂萃取,制备橡子仁乙酸乙酯、正丁醇、水萃取物,通过紫外吸收光谱、高效液相色谱分析各萃取物的化学成分组成,通过抑制率测定、抑制动力学和荧光猝灭试验分析各萃取物的体外抑酶效果及作用机制。结果表明:三种橡子仁萃取物结构高度相似,主要为单宁类物质;乙酸乙酯萃取物含表儿茶素没食子酸酯、没食子酸、没食子儿茶素没食子酸酯等9种物质;正丁醇萃取物含表儿茶素没食子酸酯、儿茶素、没食子儿茶素没食子酸酯等16种物质;水萃取物含没食子酸、绿原酸等21种物质。三种橡子仁萃取物均可有效抑制α-淀粉酶、α-葡萄糖苷酶活性,乙酸乙酯、正丁醇、水萃取物对α-淀粉酶的半抑制浓度（IC₅₀）分别为1.047、1.122、4.031 mg/mL,对α-葡萄糖苷酶的IC₅₀值分别为0.014、0.028、0.037 mg/mL。三种萃取物对两种酶的酶抑制类型多为混合型抑制,荧光猝灭类型多是以静态猝灭为主,动态猝灭为辅的混合猝灭。     

Effects of Catechins and Their Related Compounds on Cellular Accumulation and Efflux Transport of Mitoxantrone in Caco‐2 Cell Monolayers

The ability of catechins and their related compounds to inhibit breast cancer resistance protein (BCRP) function in Caco‐2 cell monolayers was investigated with mitoxantrone as a BCRP substrate. The gallate or pyrogallol moiety on the catechin structure seemed to promote increased cellular accumulation and inhibit efflux transport of mitoxantrone. The ability of gallate catechins such as (?)‐epigallocatechin gallate (EGCG) and (?)‐epicatechin gallate (ECG) to increase cellular accumulation and inhibit efflux transport of mitoxantrone was greater than that of nongallate catechins. Gallic acid octyl ester (GAO) also increased intracellular mitoxantrone accumulation. Experiments using GAO derivatives indicated that the gallate moiety required the presence of a long carbon chain for BCRP inhibition. Cellular accumulation and reduced efflux transport of mitoxantrone were greater with epigallocatechin 3‐(3″‐O‐butyl) gallate than with EGCG. EGCG inhibition of BCRP seemed to be restricted by hydrophobicity. The co‐administration of catechins, particularly EGCG and related compounds, with greater hydrophobicity may increase the therapeutic activities of BCRP substrates such as mitoxantrone.