叶酸形式、稳定性及天然化叶酸的研究进展

叶酸作为甲基供体参与了许多重要的生物化学反应过程。叶酸缺乏会引发新生儿神经管畸形、癌症、心血管疾病等。天然叶酸存在于各类食品中，但稳定性差，在加工过程中会大量损失，生物利用度低。合成叶酸常用于膳食补充剂及强化食品中，相比天然叶酸稳定性较好，生物利用度较高，但存在代谢风险。天然化叶酸是天然叶酸的稳定形式，无代谢障碍，可直接被人体吸收利用。目前，天然叶酸和合成叶酸的稳定性研究通常只聚焦在pH、温度、光照、氧气等其中一个因素。本文对比了天然叶酸和合成叶酸的代谢途径，总结了光照、温度、pH和氧气对天然叶酸和合成叶酸稳定性的影响。另外，介绍了天然化叶酸的研究进展，为其在食品领域中的开发应用提供理论依据。     

食品中维生素B_(12)和叶酸微生物检测法的研究进展

微生物检测法作为传统的经典方法,是目前国标方法中最主要的检测方法。微生物法虽然具有耗时长、准确度较低、重复性差等特点,但对于含量低,且低于仪器检出限的维生素仍然需要微生物法进行测定。微生物法目前主要应用于婴幼儿食品和乳品中维生素的检测,在其他食品类别中的研究相对较少。本文分别阐述了微生物法测定食品中维生素B_(12)和叶酸的应用情况及研究进展,主要内容包括对国标方法关键点的控制,对国标方法进行优化升级,建立了高通量快速检测方法,为微生物法测定这两种维生素提供一定的参考。食品中VB_(12)和叶酸的微生物检测方法正处于优化和开发创新的阶段,这对规范使用与提升利用率具有较大的促进作用。随着新技术的发展,高通量、多组分同时检测将是维生素检测未来发展趋势。     

用于叶酸检测的荧光传感器构建及应用研究进展

叶酸是一种水溶性B族维生素。快速且准确地检测叶酸是保证食品药品安全有效的重要手段,也是辅助临床诊断的有效途径。近年来,基于荧光传感器的叶酸检测方法因其更快的响应速度、更高的灵敏度和便捷性而受到广泛关注。本文按照构建检测叶酸用荧光传感器所用的材料进行分类,对不同类型传感器的构建及其特点进行综述。此外,介绍了这些传感器在食品药品质量控制、临床检测评估和细胞成像等方面的应用情况,并对其发展方向和应用前景进行了展望。     

植物源食品中叶酸的生物合成与调控及其提取与检测技术研究进展

叶酸作为一碳代谢时的辅因子,是生物体的必需物质,对人体健康至关重要。本文综述了植物源食品中叶酸的类型与结构、叶酸合成途径及相关酶、叶酸代谢调控、发芽富集技术、叶酸提取与检测技术,并对开发快速而准确的叶酸测定方法、研发植物性食品中叶酸的富集与提取技术进行了展望。     

产叶酸乳酸菌的筛选及对发酵乳的影响

为筛选出高产叶酸的乳酸菌并研究该乳酸菌对发酵乳的影响,采用高效液相色谱(HPLC)法从5种乳酸菌菌株:植物乳杆菌、嗜热链球菌、保加利亚乳杆菌、干酪乳杆菌、嗜酸乳杆菌的发酵液中检测叶酸含量,并通过检测复合发酵乳的pH、持水力、质构特性和感官特性来研究产叶酸的乳酸菌对发酵乳品质的影响。结果表明:植物乳杆菌产叶酸量最高,其次是嗜酸乳杆菌,分别为51.40和34.77 μg/mL。并且以基础菌发酵乳为对照组,添加产叶酸乳杆菌发酵乳为实验组,实验组与对照组相比,其质构特性和感官品质会提高,同时pH也显著下降(p<0.05)。本实验为开发功能性发酵乳提供了一定的理论依据。     

叶酸及其应用

本文对叶酸的化学结构、理化特性、来源、吸收、需要量等作了介绍,同时对叶酸的提取工艺与检测方法作了详细说明、并展望叶酸的应用前景。     

乳酸菌生物合成叶酸的研究及应用进展

叶酸是人体不可或缺的水溶性B族维生素,参与人体中核酸的生物合成、DNA甲基化反应、同型半胱氨酸再生蛋氨酸等重要的代谢活动。大部分乳酸菌的生长是消耗叶酸的,但越来越多的研究发现,很多种属的乳酸菌也具备合成叶酸的能力。使用产叶酸的乳酸菌作为发酵剂发酵食品,提高食品中的叶酸含量,是研发叶酸强化食品的新方向。文章主要对乳酸菌合成叶酸的通路、调控策略、影响因素以及作为发酵剂的应用情况和发酵产物中叶酸含量的检测方法等方面的研究进展及应用情况进行了概述,为乳酸菌叶酸合成机制的深入研究及高产叶酸乳酸菌的应用提供理论依据。     

叶酸与5-甲基四氢叶酸的生物学特征与应用

叶酸在胚胎期、出生后以及成人期都非常重要,叶酸缺乏会导致多种疾病的发生.近年来,随着国内外相关文献报道,叶酸代谢过程中的关键酶亚甲基四氢叶酸还原酶和甲硫氨酸合成酶还原酶的基因存在多态性,导致个体存在叶酸代谢障碍,由此,对于5-甲基四氢叶酸的开发研究成为关键.本文对叶酸及其代谢过程进行综述,并介绍了活性叶酸及天然化叶酸的...     

果胶提取技术研究进展

果胶是一种重要天然植物提取物,在医药、食品、化工等领域中有广泛应用。本文分别对果胶物化性质、应用及近年来国内外对其进行提取的技术研究和发展现状进行了阐述。通过与传统提取方法的比较,着重讨论各提取新技术的优势和不足,提出研究改善的重点及未来提取技术的研究发展趋势,为果胶研究和开发提供参考。     

Optim纤维及产品的开发与应用

介绍羊毛细化技术研究的方法和成果 ,主要对澳大利亚的羊毛细化技术及Optim纤维的种类、结构、性能、开发与应用进行了阐述 ,指出Optim纤维的开发与应用具有广阔的前景。     

Reduction of folic acid during baking and implications for mandatory fortification of bread

A pilot scale study designed to quantify the reduction of folic acid during bread baking in Ireland was undertaken. Flour was fortified with different concentrations of folic acid and used to make four different types of commercial bread. The dispersal of folic acid in flour on a pilot scale was variable but better homogeneity would have been achieved in the final bread due to batch size and thorough mixing of the dough. Generally, the heat degradation of folic acid during baking was between 21.9% and 32.1%. Whilst the percentage degradation of folic acid in white pan loaves, white baguettes and brown soda bread were similar the result in wholemeal bread was found to be significantly higher than in other bread types tested. Taking into account all variables affecting folic acid concentration during baking, a concentration of c. 225 μg 100 g^?1 folic acid would be needed in flour to deliver commercial bread in Ireland with an average folic acid content of 120 μg 100 g^?1 in line with Government requirements.     

Characteristics of reduced fat milks as influenced by the incorporation of folic acid

Folic acid plays an important role in the prevention of neural tube defects (e.g., spina bifida and anencephaly), heart defects, facial clefts, urinary abnormalities, and limb deficiencies. Milk and milk products serve as a potential source for folic acid fortification because of the presence of folate-binding proteins that seem to be involved in folate bioavailability. Although milk is not a good source of folic acid, fortification could help in the prevention of the above-mentioned defects. The objective of this study was to examine the physicochemical characteristics of reduced fat milks fortified with folic acid. Reduced fat milks were prepared using 25, 50, 75, and 100% of the recommended dietary allowance of 400 μg of folic acid. Treatments included addition of folic acid at these levels before and after pasteurization. Color, pH, fat, protein, viscosity, folic acid concentration, folate-binding protein concentration, folate-binding protein profile, standard plate count, and coliform counts were determined on d 1, 7, 14, and 21. A consumer acceptability test was conducted on d 7. Data from the consumer panel were analyzed using ANOVA (PROC GLM) with means separation to determine the differences among treatments. Data obtained from the color, pH, fat, protein, viscosity, folic acid concentration, folate-binding protein concentration, standard plate count, and coliform counts were analyzed using the GLM with a repeated measure in time. Significant differences were determined at P < 0.05 using Tukey's Studentized Range Test. There were no differences in the electrophoretic mobility of folate-binding protein in the samples. The concentration of folic acid was significantly higher in reduced fat milks fortified with folic acid after pasteurization compared with the treatments in which folic acid was added before pasteurization. The consumer panelists did not find any significant differences in flavor, appearance, or texture of folic acid fortified reduced fat milks compared with that of the control. Fortification of reduced fat milks with folic acid can be accomplished without adversely affecting the product characteristics.     

叶酸的提取及抗氧化性研究

研究果蔬中叶酸的最佳提取条件及叶酸的抗氧化活性.以油菜,香菇,香蕉为原料,以提取温度、提取剂的浓度、提取时间为因素进行正交试验,确定最佳提取条件,用荧光光度法测定叶酸含量.采用Fenton体系、邻苯三酚自氧化体系,分别研究不同浓度的叶酸对羟自由基( ·OH)和超氧自由基(O2-·)的清除效果.结果表明果蔬中叶酸的最佳提...     

The determination of folic acid in milk and paediatric formulae by optical biosensor assay utilising folate binding protein

Bovine milk-derived folate binding protein was evaluated during the development of a ligand binding assay for the quantitation of folic acid. An inhibition assay format using an optical biosensor platform was automated, and was compared directly with an established assay utilising a monoclonal antibody. Alternative chemistries for immobilising folic acid to the sensor surface were considered and the optimised technique was applied to the estimation of folic acid content in milk and milk-based paediatric formulae. Samples were prepared for analysis by direct dilution into buffer and heat treatment. Analysis conditions were defined and non-specific binding considerations were evaluated. Single laboratory validation performance parameters are reported and the relative affinities for the major endogenous reduced folate in milk support the attributes of the optical biosensor assay utilising folate binding protein as compared with the antibody. The future potential for application of the described assay to total folate quantitation is discussed.     

Irradiation is useful for manufacturing ready-to-eat cooked meat products enriched with folic acid

Cooked sausages enriched with folic acid (0.6, 1.2 and 2.4 mg/100 g) were manufactured as ready-to-eat (RTE) products using E-beam radiation (2-4 kGy) as a non-thermal technology. The effects of this treatment on the folic acid content, colour, texture and sensory properties of the final products were studied. The characteristics of sausages were not affected by the presence of folic acid, independently of the amount added, and their overall acceptability was good. Doses of 4 kGy caused losses of folic acid close to 20-30% and significantly decreased the sensory quality (P<0.05). Despite this, the final content of folic acid in all products was sufficient so that 50 g of product gave 100% of the recommended daily allowance (RDA). This new RTE meat product can be considered as a source of folic acid that can help assure adequate levels of this vitamin in the general population.     

Effects of excess folic acid on growth and metabolism of water-soluble vitamins in weaning rats

In order to determine the tolerable upper intake level of folic acid in humans, we investigated the effects of excessive folic acid administration on the body weight gain, food intake, tissue weight, and metabolism of B-group vitamins in weaning rats. The rats were freely fed ordinary diet containing 0.0002% folic acid (control diet) or the same diet with 0.01%, 0.1%, or 1.0% folic acid for 29 days. The body weight gains and food intakes did not differ among the four groups. Diarrhea was not seen even in the 1.0% group. Excess folic acid did not affect the tissue weights of the brain, heart, liver, kidney, spleen, lung, or testis, or urinary excretion of other B-group vitamins. These results clearly showed that feeding a diet containing up to 1.0% folic acid did not affect the food intake, body weight gain, tissue weight, or urinary excretion of B-group vitamins in weaning rats.     

Vitamin Retention During Preparation and Holding of Mashed Potatoes Made from Commercially Dehydrated Flakes and Granules

The retention of ascorbic acid, riboflavin, niacin, Vitamin B₆ and folic acid in dehydrated potato granules and flakes during home preparation and subsequent extended periods of holding at elevated temperatures on a steam table was investigated. Losses were insignificant with all vitamins during the preparation of the mashed potatoes except for riboflavin in the case of granules and folic acid in the case of flakes. Holding the mashed products on a steam table for up to 1 hr reduced the retentions of ascorbic acid and folic acid to 63% and 56% respectively in mashed potatoes made from flakes. Retention values for ascorbic acid in granules amounted to 66–67% and for folic acid they ranged from 78–86%. The holding period exerted little or no effect on retention of riboflavin, niacin, and vitamin B₆.