不同水煮时间对青椒中VitC的影响

为研究不同水煮时间对青椒中VitC含量的影响,利用高效液相色谱法测定新鲜青椒中VitC的含量,并在相同条件下,将青椒煮沸不同时间后测定青椒中VitC的含量,比较两者结果。结果表明:煮沸时间的不同,对青椒中VitC含量的影响不同,加热时间越长,青椒中VitC的含量损失越多,水中VitC的含量相对越多。     

咖啡酸维生素C酯的合成、抑菌活性和抗氧化性研究

研究了以3,4-二羟基苯甲醛、丙二酸和维生素C为原料,经过Knoevenagel缩合和直接酯化一锅法合成咖啡酸维生素C酯的方法,并考察了咖啡酸维生素C酯的抑菌活性和抗氧化性。在催化剂SO42-/ZrO2的作用下,3,4-二羟基苯甲醛与丙二酸首先发生Knoevenagel缩合生成咖啡酸,产物不需要分离,加入维生素C继续进行酯化反应,以85.1%的产率得到了咖啡酸维生素C酯,产物结构用1HNMR和IR进行确证。抑菌活性实验表明,咖啡酸维生素C酯对金黄色葡萄球菌、大肠杆菌、枯草杆菌、酿酒酵母、青霉、黄曲霉和黑曲霉均有较强的抑制作用,对细菌和酵母的抑制作用高于霉菌。抗氧化性实验表明,咖啡酸维生素C酯可以有效清除DPPH自由基和羟基自由基,清除效果明显好于维生素C。     

复合VE对延长富含油脂食品保质期的影响

为了延长富含油脂食品的保质期,对VE、Vc、柠檬酸对炒制花生粉油脂氧化酸败的抑制作用进行了研究。通过跟踪样品中过氧化值(POV)的变化来检测炒制花生粉油脂的氧化酸败程度。结果表明,VE、Vc、柠檬酸对炒制花生粉油脂氧化酸败确实有抑制作用,Vc、柠檬酸对VE的抗氧化作用有协同增效的作用,直接添加适当比例的VE、Vc、柠檬酸到炒制花生粉当中,可以延长富含油脂食品的保质期。     

维生素C棕榈酸酯乳化性能的研究

维生素C 棕榈酸酯是一种良好的抗氧化剂,在许多国家己批准作为抗氧化剂使用。本实验考察了维生素C 棕榈酸酯对两种蛋白溶液表面张力及乳化稳定性的影响,并与几种常用乳化剂的乳化能力进行了比较,认为维生素C 棕榈酸酯是一种良好的乳化剂。     

Technical note: forms and route of vitamin C supplementation for cows.

The purpose of this study was to compare the effect of multiple oral supplementation of two forms of vitamin C on plasma ascorbic acid concentrations in dairy cows. Vitamin C was administrated at the rate of 40 g/d during a 5-d period. The supplements were vitamin C in the form of a fine powder and vitamin C coated with ethyl cellulose. In addition, another group of cows provided with vitamin C in the form of fine powder through an abomasal fistula was enrolled in the study. The effect of vitamin C supplementation was assessed by the change in plasma ascorbic acid concentrations during a 5-d period of vitamin C supplementation. A tendency existed for cows that were dosed with vitamin C in the abomasum to have higher ascorbic acid than cows supplemented orally. In the abomasum-dosed cows, plasma ascorbic acid value varied between 3.6 and 4.4 micrograms/ml; the maximum ascorbic acid content was 4.4 micrograms/ml at 54 h. Cows dosed orally with vitamin C coated with ethyl cellulose had higher plasma ascorbic acid concentrations than did cows that received vitamin C in the form of fine powder. In the former group, the maximum ascorbic acid concentration occurred at 30 h after dosing (5 micrograms/ml).     

Effects of dietary vitamin C on neutrophil function and responses to intramammary infusion of lipopolysaccharide in periparturient dairy cows

Neutrophil function and the severity and incidence of mastitis in dairy cows is related to the intake of many antioxidant nutrients. Because vitamin C is the major water-soluble antioxidant in mammals, we examined the effect of dietary vitamin C on neutrophil function and responses to intramammary infusion of lipopolysaccahride (LPS) in periparturient dairy cows. At 2 wk before anticipated calving, Holstein cows were fed diets that provided 0 (16 cows) or 30 (15 cows) g/d of supplemental vitamin C (phosphorylated ascorbic acid). Treatments continued until 7 d after cows received an infusion of 10 μg of LPS into one quarter of the mammary gland (on average, this occurred 32 d postcalving). Supplementation of vitamin C increased plasma concentrations of vitamin C at calving, but no differences were observed in samples taken 24 h postinfusion. Concentrations of vitamin C in milk (24 h postinfusion) and in neutrophils (calving and 24 h postinfusion) were not affected by treatment, but vitamin C concentrations in neutrophils isolated from milk were about 3 times greater than concentrations in blood neutrophils. The LPS infusion did not alter concentrations of vitamin C in plasma or milk, suggesting that the LPS model did not produce the same effects as a bacterial infection of the mammary gland with respect to antioxidant effects. Supplemental vitamin C had no effect on neutrophil phagocytosis or bacterial kill. Dietary vitamin C reduced the milk somatic cell count but did not affect the febrile response or milk production following LPS infusion.     

Unexpected sources of vitamin C

Sausages are quite common in the Norwegian diet. Presently the vitamin C content in sausages is listed as zero in the Norwegian Food Composition Table as well as in several other countries’ food composition tables. In the present study, five different kinds of sausages were analysed for relevant nutrients including vitamin C. One composite sample consisting of 15–16 subsamples was analysed for each sausage type. Vitamin C was measured by high-performance liquid chromatography (HPLC) with electrochemical detection as the sum of l-ascorbic acid and dehydro-ascorbic acid. The vitamin C content in the analysed sausages varied from 11 to 40 mg/100 g. This is explained by addition of vitamin C as an antioxidant by the manufacturer mainly to preserve colour. When recalculating vitamin C intakes from the most recent Norwegian national dietary surveys in adults, children and youths using the updated vitamin C values, total vitamin C intake increased by 3–10%. Other processed meat products such as cold cuts may also contain vitamin C as an antioxidant, and a larger impact on vitamin C intake may be seen if also these products turn out to contain considerable amounts of vitamin C. When planning analytical projects for food composition databases, care should be taken to include vitamin C for products where this vitamin may have been added for antioxidant purposes.     

无花果中维生素C含量的测定

目的 采用分光光度法测定无花果和无花果干中维生素C的含量。方法 选取一定浓度维生素C标准液进行波长扫描, 确定维生素C的最大吸收波长, 将待测样品匀浆处理后在此波长下进行分光光度测定。结果 维生素C的最大吸收波长为520 nm, 校准曲线方程Y=0.0208X+0.001(r2=0.9998), 无花果和无花干果中维生素C含量分别为69.08 mg/100 g和64.06 mg/100 g, 加标回收实验中回收率均在90%以上。结论 无花果中含有较高的维生素C, 且无花果维生素C含量高于无花果干中维生素C含量。     

Effect of chitosan and chitooligosaccharide on vitamin C and polyphenols contents in cherries and strawberries during refrigerated storage

The objective of this research was to investigate the effect of treatment with chitosan and chitooligosaccharide on vitamin C and polyphenols contents in cherries and strawberries during refrigerated storage. Chitosans and chitooligosaccharides, as well as vitamin C and polyphenols are associated with reduced risk of cardiovascular diseases and cancer. Synthesis of vitamin C in strawberries and loss of vitamin C in cherries were observed during refrigerated storage. The treatment with chitosan and chitooligosaccharides inhibits vitamin C synthesis in strawberries and promotes vitamin C synthesis in cherries. Lower values of anthocyanin content for strawberries and higher values of anthocyanin content for cherries treated with chitosan and chitooligosaccharide compared with anthocyanin content in control strawberries and cherries were found after 7 days storage at 4 °C. Total phenols content in strawberries decreased and in cherries increased after storage 7 days at 4 °C and more pronounced changes observed for samples treated with high molecular weight chitosan. The correlation between moisture content in treated and non-treated strawberries and contents of vitamin C, anthocyanin and total phenols was shown. No correlation between moisture content and content of vitamin C, anthocyanins and total phenols was found for cherries.     

Analysis of vitamins A,E and C,iron and selenium contents in infant milk-based powdered formula during full shelf-life

The stability of vitamins A, E and C, and the iron and selenium content were determined in two types of long chain-polyunsaturated fatty acid (LC-PUFA) supplemented milk-based powdered infant formulas (IF), during an 18-month storage period at 25 and 40 °C. The first type (IF-A) was supplemented with vitamin A as retinol acetate. The second type (IF-B) was supplemented with vitamin A as retinol palmitate. Both types were also supplemented with vitamin E as α-tocopherol acetate and with vitamin C as ascorbic acid. The two formulas studied had higher vitamin A (140% and 139%), vitamin E (109% and 198%) and vitamin C (167% and 118%), but lower iron (65.0% and 65.3%) and selenium (72.9% and 79.4%) than the amounts declared on the label. As expected, all the studied vitamins showed decreases during storage, and these decreases were higher in formulas stored at 40 °C. The losses of vitamin A at 40 °C after 18 months of storage were 27.5% in IF-A and 29% in IF-B, while vitamin E losses under the same conditions were 23.1% and 28.1%, and vitamin C losses under the same conditions were 28.4% and 48.6%. All these losses justify the over-fortification of the aforementioned vitamins in these LC-PUFA supplemented IFs. Iron and selenium content remained unchanged throughout storage.     

Is the anti-stress effect of vitamin C related to adrenal gland function in rat?

The aim of this study was to investigate whether vitamin C influences the stress response system of the adrenal gland. Adrenalectomized (ADX) rats and non-ADX rats were administered vitamin C and were subjected to electroshock stress (ES) for 5 days. After loading the final stress, stress-related behaviors and corticosterone (CORT), vitamin C, and adrenocorticotropin-releasing hormone (ACTH) levels in the blood were measured. Vitamin C supplementation decreased CORT levels in non-ADX rats. Stress decreased the mean value of rearing frequency in both non-ADX and ADX rats, while vitamin C partially enhanced it only in non-ADX. Vitamin C supplementation decreased mean ACTH level in both groups. It also significantly decreased freezing time increased by stress. Lastly, vitamin C motivated both groups to cross over an electric field more frequently as compared to their respective control groups. These results suggest that the alleviating effect of vitamin C on stress-related rearing behavior was exerted via modulation of CORT, but its effect on freezing behavior may be attributed to corticotropin-releasing hormone (CRH) or ACTH.     

VC脂质体的制备与稳定性测定

以卵磷脂和胆固醇为膜材,采用薄膜- 超声法制备VC 脂质体。通过单因素考察生产工艺对包封率的影响以及正交设计法进行工艺优化。得出制备VC 脂质体最佳工艺：制备温度65℃、卵磷脂:胆固醇=5:1、总脂材:VC=25:1、总脂材:表面活性剂(吐温-80)=10:2,在此条件下包封率可达42.1%,平均粒度为373.9nm;将脂质体在4℃下密闭放置15d,以脂质体的粒径变化为指标考察其稳定性。结果表明,脂质体悬液粒径无明显变化,脂质体悬液稳定性良好。     

Effect of maternal dietary vitamin C intake on the level of vitamin C in breastmilk among nursing mothers in Baghdad,Iraq

The vitamin C content of breastmilk was investigated in a group of nursing mothers attending maternal and child health centers in Baghdad during 1998-2000. Two hundred healthy, nonsmoking, 28- to 38-year-old lactating women were studied. Individual samples of breastmilk were obtained for estimation of vitamin C. Dietary data were collected by using 24-hour food recalls. The mean intake of vitamin C was far below the Food and Agriculture Organization/World Health Organization requirement of 26 +/- 2.13 (SD) mg/day). The vitamin C content of breastmilk was significantly correlated with the maternal intake of vitamin C (r = 0.61, p < .01). The vitamin C content of breastmilk varied with the season. The level was much higher in summer (3.9 +/- 1.05 mg/100 ml) than in winter (3.02 +/- 2.01 mg/100 ml; p < .05). This fluctuation indicates the dependence of breastmilk vitamin C on dietary intake. The results show the need to increase the consumption of vegetables and fruits and to monitor maternal ascorbic acid intake.     

蓝靛果微波泡沫干燥过程中维生素C降解过程模拟

受干燥条件影响,食品原料中营养成分常发生降解,为阐明微波泡沫干燥条件对蓝靛果中维生素C稳定性的作用规律,本研究在对各影响因素进行通径分析的基础上,分阶段建立维生素C降解动力学模型,并据此建立多物理场仿真模型.结果表明:干燥过程中物料温度和含水率对维生素C降解同时存在直接影响和间接影响,温度升高和含水率下降均会导致维生素...     

北京地区几种野菜主要营养素的测定

本文对北京地区自然条件及人工规模化栽培条件下生长的几种野菜叶片在采收后进行处理保存，定期测定氨基酸与维生素C的含量。结果表明：野菜中含有的氨基酸种类和数量随时间的延长变化不大；野菜在人工规模化栽培条件下维生素C的含量少于自然条件下生长时维生素C的含量：热烫处理有降低维生素C含量作用。     

外源因素对萌发大豆中VC含量的影响

大豆不含VC,但在萌发过程中会产生VC,且生成量随萌发天数的延长而增加。在大豆萌发过程中分别采用葡萄糖、L-半乳糖、D-甘露糖、碘化钾浸泡以及紫外光照射,研究外源因素对VC含量的影响。结果表明：葡萄糖、L-半乳糖、碘化钾溶液浸泡以及紫外光照射对VC合成均有不同程度的促进作用,其中L-半乳糖浸泡的作用最大,与未处理相比VC增加了8.43mg/100g;其次是葡萄糖浸泡,VC增加了4.23mg/100g,且较低葡萄糖质量浓度下延长浸泡时间优于高质量浓度短时浸泡。紫外光照射从第5天开始对VC合成的促进作用明显加强。     

The hepatoprotective potential of Spirulina and vitamin C supplemention in cisplatin toxicity

Spirulina platensis is a microalgae with potent dietary phyto-antioxidant, anti-inflammatory and anti-carcinogenic properties. We investigated the mechanism of cisplatin induced hepatotoxicity and whether this natural antioxidant provided protection against cisplatin hepatotoxicity. The study was carried out in a mice model where the animals were segregated into different groups according to their treatments, e.g. control group with no treatment, cisplatin treated, cisplatin + Spirulina treated, cisplatin + vitamin C treated and cisplatin + Spirulina + vitamin C treated. The liver marker enzymes were found to be elevated following cisplatin treatment, signifying hepatotoxicity. The supplementation of Spirulina and vitamin C could effectively bring down the levels of these enzymes. Light microscopy also showed that cisplatin treatment induced liver injury and that histopathological abnormalities were prevented by Spirulina and vitamin C supplementation. This protective effect was further substantiated by the estimation of antioxidant levels and extent of lipid peroxidation in the Spirulina, vitamin C and Spirulina + vitamin C supplemented groups as compared to cisplatin alone.     

Nutrient content of milk and milk products: vitamins of the B complex and vitamin C in retail market milk and milk products

A survey was undertaken to update and extend information on the water-soluble vitamin content of milk and milk products on retail sale. The results are discussed in relation to previously published data. Apart from vitamin C the levels of vitamins in retail pasteurized cows' milk were very similar to those found in milk from the processing dairy. Levels of total vitamin C and folic acid in UHT full cream milk were negligible; vitamin B₆ and vitamin B₁₂ were respectively 73 and 56% of the levels in pasteurized milk. Except for nicotinic acid, pantothenic acid and biotin, the levels of vitamins in sterilized milk were lower than in pasteurized milk, particularly vitamin C, folic acid and vitamin B₁₂. When compared on an equivalent dilution basis, vitamin B₆, thiamine, folic acid and, especially, vitamin B₁₂ in evaporated milk were lower than in pasteurized cows' milk. In comparison, in full cream condensed milk only vitamin B₆ was particularly low; vitamin C was particularly well preserved. With the exception of vitamin B₁₂, vitamin levels in reconstituted spray dried milk were similar to those in pasteurized cows 'milk. Levels in filled' spray dried milk were on average 70% of those in ordinary dried milks. Apart from vitamin B₁₂ the levels of B vitamins in non health food yogurt were generally higher than in pasteurized milk, especially folic acid. The levels of vitamin B₁₂ and folic acid in goats' milk were only 22 and 11 % respectively of those in cows' milk, but the nicotinic acid level was four times higher. The level of vitamin C in raw sheep's milk was about five times that in pasteurized cows' milk; other levels, apart from folic acid which was similar, were between 1.3 and 5.2 times those in cows' milk.     

Effects of Processing and Storage on the Water-Soluble Vitamin Content of Human Milk

Effects of four heat treatments (62.5°C, 30 min; 72°C, 15 sec; 88°C, 5 sec; and 100°C, 5 min) and frozen storage (?20°C, 4 wk) on water-soluble vitamin content of composite samples of mature human milk were determined. No changes in riboflavin, biotin, and total pantothenic acid content were observed after any of the treatments. Heating at 100°C for 5 min decreased thiamin, vitamin B₁₂, and vitamin C contents. Vitamin Bs content was reduced by heating at 88°C and 100°C. Free folate was not affected by heating while total folate concentration was decreased similarly by all heat treatments. During frozen storage at ?20°C, niacin and free pantothenic acid concentrations were reduced; riboflavin, vitamin Bs, biotin, total pantothenic acid, vitamin C, and vitamin B₁₂ were unaffected; while measurable thiamin and free folate concentrations increased. Overall, the two lower temperature treatments were less detrimental to the water-soluble vitamins in human milk.     

Changes in vitamin C concentrations in plasma and milk from dairy cows after an intramammary infusion of Escherichia coli

Plasma and milk concentrations of ascorbic acid and dehydro-L-ascorbic acid (DHAA) were measured before and after 21 Holstein cows (approximately 26 DIM) were given an intramammary infusion of Escherichia coli. Blood, milk from the unchallenged quarters, and milk from the challenged gland were sampled immediately before challenge (d 0) and 24 h and 7 d postchallenge. Plasma vitamin C (ascorbic acid + DHAA) concentrations decreased 39%, and concentrations of vitamin C and ascorbic acid in milk from the challenged quarter decreased 52 and 62%, respectively, in samples taken 24 h postchallenge. No change was observed in vitamin C concentrations in milk from unchallenged quarters. The concentration of DHAA in milk from challenged quarters increased 67% 24 h postchallenge. The duration of clinical mastitis, peak body temperature, number of colony-forming units of E. coli isolated from the infected gland, and loss in milk yield were associated with a change in concentration of vitamin C in milk from the challenged quarter. Increased severity of clinical signs was associated with large decreases in concentration of vitamin C in milk from the challenged quarter. Similar, but statistically weaker, relationships were observed for changes in plasma vitamin C concentrations.