共查询到19条相似文献,搜索用时 171 毫秒
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脂肪酸值的大小及变化是判断粮食品质变化的重要指标,是现有分析粮食品质的一种重要方法.但其测定过程中的影响因素较多,测定结果的再现性也较差,文章对粮食脂肪酸值测定过程中的主要影响因素进行了分析和探讨. 相似文献
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研究了环糊精抑制脂肪氧合酶催化活性的影响因素,单因素实验发现环糊精浓度、反应体系的温度、pH以及Fe3+和Fe2+均影响环糊精抑制脂肪氧合酶活性的行为;正交实验发现,在温度35℃,pH4.0,环糊精浓度为10mmol/L,Fe3+浓度为0.005μmol/L,Fe2+浓度为0.01μmol/L的条件时,环糊精抑制脂肪氧合酶达到最好抑制效果。以上结果表明,环糊精能够直接与脂肪氧合酶发生作用,从而抑制脂肪氧合酶的活性,但该行为受环境条件的影响。本文为CD-酶超分子体系的研究以及CD在大豆除腥中的应用提供一定的参考。 相似文献
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过氧化值是用来衡量油脂酸败程度,从而衡量油脂质量的一项指标。该指标的检测大多采用碘量法。由于油脂氧化过程复杂,所形成的氢过氧化物极不稳定,加上碘量法测定的影响因素也很多,使测定结果的精确性受到影响。多次试验表明,油脂氧化的时间阶段性、溶液的pH值、测定的温度、加水量、反应时间长短和摇动的剧烈程度等都对其测定结果产生明显的影响。 相似文献
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辐照及贮藏条件对食品脂肪氧化影响的研究 总被引:9,自引:1,他引:9
^60Coγ射线辐照能加速食品脂肪氧化,辐照食品在贮藏的前期,其脂肪氧化速度与对照相比无明显区别,随着贮藏时间的延长,其脂肪氧化速度明显加快;不同辐照食品的脂肪氧化速度不同;贮藏温度对辐照食品脂肪氧化的影响较大,贮藏温度越高,脂肪氧化速度越快,但温度对不同辐照食品脂肪氧化的影响程度有所差别;抗氧化剂可明显地抑制吃一堑照对食品脂肪氧化的影响和贮藏温度对辐照食品脂肪氧化的影响。 相似文献
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乳粉制品中脂肪过氧化值测定方法的研究 总被引:3,自引:0,他引:3
阐述了乳粉制品中脂肪过氧化值的测定方法;比较了提取脂肪时试样经干燥和未经干燥对过氧化值的影响;比较了不同提取溶剂对过氧化值的影响。结果表明,在提取脂肪时试样不需要进行干燥,采用石油醚做提取溶剂。 相似文献
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Khalid M Al‐Ismail Mohammad A Humied 《Journal of the science of food and agriculture》2003,83(1):39-43
Brined white (Nabulsi) cheese was studied for cholesterol oxidation and for oxidative and hydrolytic rancidities during cheese processing, during storage in closed transparent and light‐protected glass jars at room temperature for 3, 6 and 9 months and during storage on an open tray exposed to atmospheric air and light for 1, 2 and 3 weeks. The peroxide value (PV), free fatty acid (FFA) content and 7‐ketocholesterol level were determined. The cheese processing steps (curd formation, salting and boiling in brine) had no significant effect on PV, FFAs and 7‐ketocholesterol. However, the storage conditions had a significant effect (p ≤ 0.5) on these parameters. Peroxides were not detected or were very low in the freshly boiled cheese, while the FFA content was 2.9 g kg?1. The PV and FFA content increased to approximately 5 meq kg?1 and 11 g kg?1 respectively after 9 months of storage in transparent or light‐protected jars. The 7‐ketocholesterol level was 1.2 µg g?1 in the freshly boiled cheese and reached maximum values of 2.3 and 5.2 µg g?1 after 9 months of storage in light‐protected and transparent jars respectively. Cheese samples displayed on an open tray showed a higher increase in PV, FFAs and 7‐ketocholesterol than samples stored in closed jars, reaching values of 6.1 meq kg?1, 6.8 g kg?1 and 8.8 µg g?1 respectively after 3 weeks of storage. © 2002 Society of Chemical Industry 相似文献
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Only a few results are available on the size of human milk fat globules (MFG), despite its significance regarding fat digestion in the infant, and no data are available at <24 h postpartum (PP). We measured the MFG size distribution in colostrum and transitional human milk in comparison with fat globules of mature milk and infant formula. Colostrum and transitional milk samples from 18 mothers were collected regularly during 4 d PP and compared with mature milk samples of 17 different mothers and 4 infant formulas. The size distribution was measured by laser light scattering. For further characterization, the ζ-potential of some mature MFG was measured by laser Doppler electrophoresis. The MFG diameter decreased sigmoidally in the first days. At <12 h PP, the mode diameter was 8.9 ± 1.0 μm vs 2.8 ±0.3 μm at 96 h PP. Thus, the surface area of MFG increased from 1.1 ±0.3 to 5.4 ±0.7 m2/g between colostrum and transitional milk. In mature milk, the MFG diameter was 4 μm on average and increased with advancing lactation, whereas the droplets in infant formula measured 0.4 μm. The ζ potential of mature MFG was −7.8 ± 0.1 mV. The fat globules are larger in early colostrum than in transitional and mature human milk and in contrast with the small-sized fat droplets in infant formula. Human MFG also have a low negative surface charge compared with bovine globules. These structural differences can be of nutritional significance for the infant. 相似文献
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