人体营养的微量元素(二)

七、钴在微量元素中,只有钴必须以特殊结合形式——氰基钻胺,即维生素B_(12),供应,才能在人体内有生理作用。所以钴在人类营养中的问题主要是维生素B_(12)的膳食来源、供给、吸收问题,而不是钴本身的问题。所有一般膳食中含的钴只有很小一部分来自维生素B_(12),其钴含量与维生素B_(12)含量不一定有相关。FAO/WHO联合专家组在1970年发表了人体的维生素B_(12)需要量和建议的每日摄入量,并考虑到食物中影响这种维生素稳定性及其利用     

用大肠桿菌测定豆类发酵食品中维生素B_12的活性

用大肠桿菌测定维生素B12,培养基简单,方法易於掌握,但蛋氨酸有干摄作用。豆类发酵食品中游离的蛋氨酸含量很高,不能使用以碱破壞维生素B12来改正结果的方法。本实验利用活性炭吸附作用,以pH4.5的醋酸纳缓(?)液洗脱去蛋氨酸,最後用热的65％酒精洗脱吸附在活性炭上的维生素B_12,其回收率平均为98.8％。由於酒精洗脱液含有极微量的蛋氨酸,在测定时仍应与碱破壤法结合使用。 利用此种方法分析了9种发酵食品,其中以臭豆腐乳含量最高,每百克合有1.88—9.800微克的稚生素B_12活性。     

维生素B_(12)与叶酸对辐射损伤的效应研究——一、尿中亚胺甲基谷氨酸排出量

选取刚断奶的雄性大鼠,饲以含有1％琥珀酰磺胺噻唑的、无维生素B_(12)和叶酸的饲料,并经口每日每鼠补给不同量维生素B_(12)和叶酸,以组氨酸负荷尿中亚胺甲基谷氨酸的排出量为主要指标,观察急性辐射损伤时维生素B_(12)与叶酸的营养效应。其主要结果如下: 1.当大鼠仅摄食实验饲料,3—5周内就出现了明显的缺乏维生素B_(12)与叶酸的症状,如食欲锐减,体重增长率减慢继而下降,尾血白细胞总数下降,24小时尿中亚胺甲基谷氨酸排出量明显高于正常(由正常的0.55mg增至14～17mg)等。摄食维生素B_(12)0.02μg与叶酸0.5μg组的上述症状较未补充者轻。摄食维生素B_(12)0.1μg与叶酸2.5μg组的食欲、体重增长率等已较正常,但组氨酸负荷尿中亚胺甲基谷氨酸排出量仍高于正常(由正常0.55mg增至3.41mg)。摄食维生素B_(12)0.3μg与叶酸7.5μg组在上述各项指标上均显示与正常无差别。) 2.上述经口补充不同量维生素B_(12)与叶酸的各组动物,经700rad照射(实验饲养36天时后,除摄食维生素B_(112)0.3μg与叶酸7.5μg组外,其余两组的组氨酸负荷尿中亚胺甲其谷氨酸排出量均比照射前更为增加,(分别由12.36增至23～28mg、3.41增至6～9mg/24h),显示照后此两种维生素的缺乏或不足程度加重。 3.摄食维生素B_(12)0.02μg与叶酸0.5μg的大鼠?     

B族维生素片中维生素B_(12)电感耦合等离子体质谱法间接测定

目的建立电感耦合等离子体质谱(ICP-MS)法间接测定B族维生素片中维生素B_(12)含量的方法。方法样品经微波消解后,采用在线加入内标校正基体效应,用ICP-MS测定钴离子浓度间接测定样品中维生素B_(12)的含量。结果本方法在1.0~100.0μg/L线性范围内具有良好的线性关系(r0.999),加标回收率为95.0%~104.0%,相对标准偏差(RSD)为1.17%~3.03%,方法检出限为0.014 mg/kg,定量下限为0.041 mg/kg。结论本方法简单、灵敏、准确,适用于B族维生素片中维生素B_(12)的测定。     

中老年人易缺乏的营养素

维生素A(和可转化为维生素A的β—胡萝卜素) 存在于深绿色叶菜类及黄色蔬菜中,可以使眼睛适应昏暗光线,保护皮肤组织。摄入较多的维生素A虽不能医治弱视,但摄入不足会使中老年人视力受到损害。 叶酸 属于B族维生素,有助于机体产生红细胞,摄入不足会产生贫血症。富含叶酸的食物有:叶菜类、绿色蔬菜、某些水果、豆类、肝脏、强化谷物制品、小麦胚芽和强化麦片。 维生系B_(12) 也叫钴胺素,与叶酸一起产生红细胞。摄入不足同样会产生贫血症,某些老年人还会引起神经方面的问题。肉、鱼、蛋、乳制品都含有丰富的维生素B_(12)。中老年人应多吃维生素B_(12)强化的食品及补充剂。     

维生素B_(12)和甲钴胺有区别吗

正张大爷患糖尿病10多年,近来感觉双脚发凉和麻木。医生诊断是糖尿病并发周围神经炎,开了甲钴胺片(弥可保)给他服用。张大爷听病友说,甲钴胺和维生素B_(12)是同类药,但价格大大高于维生素B_(12),因此他向医生咨询:能否用维生素B_(12)替代甲钴胺?维生素B_(12)和甲钴胺是同一药物吗?维生素B_(12)是具有钴啉环结构的维生素B族化学物质的总称。首先发现的是氰钴胺,按维生素命名排序     

中国传统发酵豆制品维生素K2含量分布

目的 测定不同类型的发酵豆制品中维生素K₂含量，分析维生素K₂含量的差异。方法 综合考虑中国传统发酵豆制品(豆豉、腐乳、豆酱)工艺、地域、销量、原料、风味等因素，纳入98种典型发酵豆制品，运用高效液相色谱法测定发酵豆制品中维生素K₂主要亚型的含量，并分析主要的影响因素。结果 中国豆类发酵食品普遍含有维生素K₂,且以甲萘醌-7亚型为主。豆豉的维生素K₂含量最高，为437.55μg/100 g,腐乳和豆酱中维生素K₂含量较低，分别为7.48μg/100 g和2.47μg/100 g。细菌型豆豉中维生素K₂含量(403.94μg/100 g)高于毛霉型豆豉(232.98μg/100 g)和米曲霉型豆豉(81.00μg/100 g)(P<0.05),黄豆型豆豉(610.41μg/100 g)中维生素K₂含量大于黑豆型豆豉(178.08μg/100 g)(P<0.05),干豆豉中维生素K₂...     

新用维生素B12

维生素B_(12)又叫钴胺素,是目前已知维生素中唯一含金属元素的一种,而其所含的金属元素钴也只有以维生素B_(12)的形式才能发挥微量元素的作用。如果缺乏维生素B_(12)会影响核酸、蛋白质的生物合成及脂肪酸的代谢,抑制骨髓血细胞的成熟,使中枢神经系统发生退行性病变,导致恶性贫血。     

美女莫忌荤

爱美,是女人的天性。现实生活中,一些女性为追 求健美苗条的体态,不顾一切地节食减肥,并将 鱼、肉等荤食视为饮食之忌,一日三餐,滴荤不沾,造成营养不足,严重影响了身体健康。 在日常饮食中,维生系B_(12)最为缺乏,肉类食品是唯一能提供足量维生素B_(12)的食品。一些植物蛋白如花生、豆类虽也含有微量的维生素B_(12),但由于甚少且不易被机体吸收,所以根本不能满足身体需要。长期素食者会因维生素B_(12)缺乏引起口腔、神经方面病症,还会     

男性不孕与维生素B_(12)

维生素B_(12)在机体内以氰钴胺(CN-B_(12))、羟钴胺(OH-B_(12))、钴酰胺(DBCC)、甲钴胺(CH_3-B_(12))的形式存在,只有DBCC与甲钴胺在体内有辅酶活性,尤其是甲钴胺参与转甲基反应,促进体内核酸、蛋白合成与磷脂合成等,因此,男性不孕症与维生素B_(12)的关系受到了重视。一、维生素B_(12)缺乏时对雄性生殖器官的影响及给与维生素B_(12)的效果维生素B_(12)缺乏实验主要是对血象与代谢等进行观察,关于各器官变化的报告不多,尤其对雄性生殖器官影响的研究报道很少。梅村给大鼠以缺乏维生素B_(12)的饮食达115日,从组织学上研究全身各器官,发现     

2010年杭州市售发酵性食品中氨基甲酸乙酯调查与分析

目的 调查2010年杭州市售发酵性食品中氨基甲酸乙酯含量.方法 2010年在杭州大、中、小型3家超市采集237份发酵性食品,包括黄酒、白酒、葡萄酒、啤酒、料酒、酱油、食醋、腐乳等8类食品,采用D5-氨基甲酸乙酯核素稀释技术,硅藻土固相萃取净化样品,然后用气相色谱-质谱法测定样品中氨基甲酸乙酯.结果 237份发酵性食品中氨基甲酸乙酯检出率为100%,含量范围为2.0 ~515.0 μg/kg,氨基甲酸乙酯含量平均值(中位数)从高到低依次为红腐乳[182.2 μg/kg(161.2 μg/kg )]、黄酒[159.6 μg/kg(121.0 μg/kg)]、料酒[86.8 μg/kg(95.6 μg/kg)]、白酒[72.0 μg/kg(60.5 μg/kg )]、酱油[47.2 μg/kg(40.7 μg/kg)]、食醋[26.7 μg/kg(31.8 μg/kg )]、葡萄酒[15.7 μg/kg(16.8 μg/kg )]、啤酒[2.2 μg/kg(2.3 μg/kg)].结论 2010年杭州市发酵性食品中均存在氨基甲酸乙酯,尤以红腐乳、黄酒中氨基甲酸乙酯含量为高.

Abstract：

Objective To observe the ethyl carbamate concentrations in different commercial fermented foods in Hangzhou in 2010.Methods In 2010,237 commercial fermented food samples of eight categories,including yellow wine,white spirit,wine,beer,cooking wine,sauce,vinegar and fermented bean curd,were purchased from 3 different size markets respectively in Hangzhou.The ethyl carbamate was measured by gas chromatography-mass spectrometry in selection ion mode,after the samples were coupled with D5-ethyl carbamate,and purified by diatomite solid phase extraction column.Results The results showed that ethyl carbamate was detected in all samples analyzed (100%) with the range from 2.0 μg/kg to 515.0 μg/kg.The ethyl carbamate average(median)levels in 8 food catergories were descending with fermented red bean curd (182.2 μg/kg (161.2 μg/kg)),yellow wine (159.6 μg/kg (121.0 μg/kg)),cooking wine (86.8 μg/kg (95.6 μg/kg)),white spirit (72.0 μg/kg (60.5 μg/kg)),soy sauce (47.2 μg/kg(40.7μg/kg)),vinegar (26.7 μg/kg (31.8 μg/kg)),wine (15.7 μg/kg (16.8 μg/kg)) and beer (2.2 μg/kg (2.3 μg/kg)).Conclusion The ethyl carbamate was detected in all fermented foods in Hangzhou in 2010,and the levels of ethyl carbamate in red bean curd and yellow wine were higher than others.     

Discovery of an S-equol rich food stinky tofu,a traditional fermented soy product in Taiwan

A recent epidemiological study showed that daily intake of mg quantities of S-equol is required for health-promoting effects in menopausal women. However, the maximum equol content in food was reported to be approximately 130 μg/100 g in egg yolk. The objective of this study was to find a high equol-containing food. We measured the equol content of 33 egg yolks and 21 fermented soybean foods. Equol was detected in 28 egg yolks at the maximum content of 43 μg/100 g. In the fermented soybean foods, equol was detected only in stinky tofu. We examined 16 stinky tofu samples purchased during different seasons and the average equol content was 1.39 mg/100 g, ranging from 0.34 to 2.68 mg/100 g. Equol was present in stinky tofu as the S-enantiomeric form and as an aglycon type. This is the first report demonstrating that stinky tofu contains high levels of S-equol, which may exert beneficial effects in menopausal women.     

烟台市发酵性调料中氨基甲酸乙酯污染状况调查

目的:探讨烟台市发酵调料中氨基甲酸乙酯(ethyl carbamate,EC)污染状况,对本地区发酵性调料的食品安全性进行调查与评估。方法:随机选取2011年烟台市超市及食品供销部的158份发酵食品,应用基质固相分散萃取(MSPD)技术GC/MS定量分析各类发酵调料食品中EC的含量。结果:(1)158份发酵性调料食品中阳性样品数为117份,阳性率为74.05%,其中黄酒及料酒中EC阳性率最高,平均含量分别为73.1μg/kg、66.4μg/kg,酱油和食醋中EC的含量相对较低,平均含量为40.3μg/kg、29.1μg/kg,腐乳EC平均含量为27.5μg/kg;(2)EC阳性腐乳样品数为36份,其中红腐乳19份,白腐乳17份,两组间EC含量水平无显著差异性。结论:烟台市发酵调料食品中普遍存在EC,其中黄酒及料酒中EC阳性率最高,且EC含量最高值为100.2 mg/L,发酵调料的食品安全问题应进一步加强监管、严格调控。     

Vitamin profile of some standardized nigerian composite dishes

The purpose of the study was to determine the vitamin content of twenty standardized dishes commonly consumed in Nigeria. Representative samples of twenty Nigerian dishes were analyzed for fat-soluble (vitamins A, D, E, and K) and water-soluble (vitamin C and B- complexes) vitamins. The foods analyzed included those based on cereals, starchy tubers and roots, legumes, and vegetables. The analysis was carried out using spectrophotometry. The results revealed the following concentrations (mg/100 g): vitamin C , undetectable to 2.692 mg/100 g; thiamine, 0.011-1.094 mg/100 g; riboflavin, 0.011-0.816 mg/100 g; pyridoxine, undetectable to 0.412 mg/100 g; niacin, 0.070-0.967 mg/100 g; pantothenic acid, 0.060-1.193 mg/100 g; biotin, undetectable to 2.092 mg/100 g; B12, 0.045-2.424 μg/100 g; folate, 7.822-101.764 μg/100 g; total vitamin A, undetectable to 121.444 μg RE/100 g; vitamin D, undetectable to 2.445 IU/100 g; vitamin E, undetectable to 2.627 IU/100 g; and vitamin K, 0.266-13.091 μg/100 g. The results suggest that these dishes are good sources of fat-soluble and water-soluble vitamins and will provide baseline data that will be valuable in complementing available food composition data, and in estimating dietary intake of vitamins in Nigeria.     

Vitamin K content of foods and dietary vitamin K intake in Japanese young women

Several reports indicate an important role for vitamin K in bone health as well as blood coagulation. However, the current Adequate Intakes (AI) might not be sufficient for the maintenance of bone health. To obtain a closer estimate of dietary intake of phylloquinone (PK) and menaquinones (MKs), PK, MK-4 and MK-7 contents in food samples (58 food items) were determined by an improved high-performance liquid chromatography method. Next, we assessed dietary vitamin K intake in young women living in eastern Japan using vitamin K contents measured here and the Standard Tables of Food Composition in Japan. PK was widely distributed in green vegetables and algae, and high amounts were found in spinach and broccoli (raw, 498 and 307 microg/100 g wet weight, respectively). Although MK-4 was widely distributed in animal products, overall MK-4 content was lower than PK. MK-7 was observed characteristically in fermented soybean products such as natto (939 microg/100 g). The mean total vitamin K intake of all subjects (using data from this study and Japanese food composition tables) was about 230 microg/d and 94% of participants met the AI of vitamin K for women aged 18-29 y in Japan, 60 microg/d. The contributions of PK, MK-4 and MK-7 to total vitamin K intake were 67.7, 7.3 and 24.9%, respectively. PK from vegetables and algae and MK-7 from pulses (including fermented soybean foods) were the major contributors to the total vitamin K intake of young women living in eastern Japan.     

Nutritional Profile of Local and Western Fast Foods Consumed in Bahrain

The aim of this study was to determine the proximate, mineral, and vitamin content of 16 commonly consumed fast foods (local and Western-based) in Bahrain. Samples were collected from several food outlets in Manama city, the capital of Bahrain, and analyzed using standard methods. In general, the findings revealed that local fast foods had higher cholesterol and energy content (ranging from 0–118 mg and 762–1796 kJ/100 g, respectively) compared to Western fast foods (ranging from 11–34 mg/100 g and 980–1172 kJ/100 g, respectively). Protein content was higher in most of the local fast foods compared to the Western fast foods (5.8–30.4 g/100 g and 10.3–17.9 g/100 g, respectively). Most of the minerals were higher in local fast foods, but calcium (16–153 mg/100 g) and phosphorous (54–273 mg/100 g) were higher in Western fast foods. Some of these foods had considerable levels of vitamin B₆ (0.03–0.25 mg/100 g), vitamin B₁₂ (0.1–2.3 μg/100 g), folacin (9.0–106 μg/100 g), and niacin (1.0–12.1 mg/100 g), while the rest of the vitamins were present to a lesser extent. Fat, energy, and sodium levels were also higher in local fast foods. It is evident that the conception that local fast foods are healthier than Western-based fast foods is inappropriate. Hence, nutrition education programmes need to focus on the nutritional aspects of both local and Western fast foods.     

Determination of vitamin D3 in margarines, oils and other supplemented food products using HPLC

The vitamin D3 content of high fat foods, such as margarines and oils, was determined by liquid chromatography. The method involved sample saponification and an extraction process, in which the purification of the non-saponifiable matter was the critical step. A semi-preparative straight-phase clean up procedure was used to produce an adequately purified sample solution prior to the final analytical quantification step. Vitamin D2 was used as internal standard when estimating the vitamin D3 content. The overall recoveries depended on the fat content of the food sample and varied from 40% for margarines to 80% for low-fat products at a concentration of about 10 micrograms/100 g. The minimum detectable amount was 0.36 ng vitamin D3. The mean relative recovery of vitamin D3 in relation to vitamin D2 was calculated to be 0.97.     

Energy,Sugars, Iron,and Vitamin B12 Content of Commercial Infant Food Pouches and Other Commercial Infant Foods on the New Zealand Market

There has been an important shift in the New Zealand infant food market over the past decade, with the majority of complementary foods now sold in “pouches”. Along with the increasing market share of commercial infant food pouches internationally, there have been growing concerns about their nutritional quality. However, research examining the nutritional quality of these pouches compared to other forms of commercial infant foods in New Zealand has not been undertaken. Nor have any studies reported the free sugars or added sugars content of these foods. To address this knowledge gap, a cross-sectional survey of infant foods sold in New Zealand supermarkets was conducted in 2019–2020. Recipes and nutrient lines were developed for the 266 foods identified (133 food pouches). The energy, iron, vitamin B12, total sugars, free sugars, and added sugars content of infant food pouches and other forms of commercial infant foods per 100 g were compared, both within food groups and by age group. Infant food pouches contained similar median amounts of energy, iron, and vitamin B12 to other forms of commercial infant foods but contained considerably more total sugars (8.4 g/100 g vs. 2.3 g/100 g). However, median free sugars and added sugars content was very low across all food groups except for “dairy” and “sweet snacks”. All “dry cereals” were fortified with iron whereas none of the infant food pouches were. Therefore, consuming food pouches to the exclusion of other commercial infant foods may place infants at risk of iron deficiency if they do not receive sufficient iron from other sources.     

Loss of vitamin B(12) in fish (round herring) meats during various cooking treatments

The loss of vitamin B(12) in round herring meats during various cooking treatments was evaluated. Although amounts of vitamin B(12) were three times greater in the viscera (37.5 ± 10.6 μg/100 g fresh weight) than in the meats, about 73% of total vitamin B(12) found in the whole fish body (except for head and bones) were recovered in the meats (5.1 ± 1.0 μg of vitamin B(12)). The vitamin B(12) contents of the round herring's meats were significantly decreased up to ~62% during cooking by grilling, boiling, frying, steaming, and microwaving. There was, however, no loss of vitamin B(12) during vacuum-packed pouch cooking. Model experiment using hydroxocobalamin suggest that loss of vitamin B(12) is dependent on the degree of temperature and time used in conventional cooking, and is further affected by the concomitant ingredients of food. Retention of vitamin B(12) was not dependent on vacuum or temperature (or both) used in the vacuum-packed pouch cooking.     

Soy food intake behavior by socio-demographic characteristics of Korean housewives

In this study, the soy food intake behaviors including perception and intake frequency of soybean foods by sociodemographic variables were analyzed in housewives. The perception of housewives for soy foods showed that soybean paste, soybean curd, and Dambuk were high in the descending order for nutritional quality and health promotion effect, and soybean paste received the highest score in taste and flavor. Soybean sprouts received the highest evaluation score in the economic aspect. In the aspect of safe food, soybean paste received the highest evaluation score, as mush as a traditional food. The analysis of perception by sociodemographic variables showed that soybean curd, Dambuk, and soybean sprouts had higher perceptions as education level increased, and soy milk had higher perceptions in subjects with younger age and with employment. In the intake frequency, more than 50% of the subjects had soybean curd, soybean sprouts, and soybean paste more than once a week. The analysis for correlation between the intake frequency of soy foods and the degree of perception showed that taste and flavor had high correlation with the intake frequency of soy foods except soybean sprouts. The intake frequency of soybean paste, Dambuk, and soy milk had positive correlations to familiarity and that of soy milk had positive correlations to nutrition and health perception, and those of soybeam paste, soybean sprouts, and soy milk had positive correlations to safe food perception. From the above results, housewives in Korea had very high perceptions to nutritional quality and health promotion effect of soy foods and the degree of perception and accompanied intake frequency had significant differences by age, education level, and economic level among sociodemographic variables.