无籽西瓜果实不同部位维生素C和番茄红素含量测定

为了研究西瓜不同部位维生素C、番茄红素含量,对6个红瓤和1个黄瓤无籽西瓜品种果实不同部位总维生素C(TAA)、还原型维生素C(AA)、氧化型维生素C(DHAA)和番茄红素含量进行测定,并检测红瓤无籽西瓜整瓜贮藏2个月后各成分损失率。结果表明,不同无籽西瓜品种之间果实TAA、AA和DHAA及番茄红素含量差异显著;果实不同部位TAA、AA和DHAA及番茄红素含量也有很大差异,中间部位均大于近皮部。TAA、DHAA和番茄红素含量相关性达到极显著水平,AA和DHAA含量相关性达到显著水平。室温下整瓜贮藏2个月后果实不同部位TAA、AA、DHAA和番茄红素含量损失率为20%～50%。     

不同微波渗糖工艺对低糖果脯维生素C保存的影响

研究了预处理方式、微波渗糖和干燥工艺等不同加工工艺对低糖果脯维生素C保存的影响,通过追踪测定各个工艺环节中维生素C保存的变化来寻求最佳微波渗糖工艺条件。结果表明,3种预处理方式在维生素C含量保存上以食盐预处理最好,微波预处理次之,热水漂烫预处理最差,质量分数2%的食盐溶液中浸泡30 min时果坯维生素C含量为1.083 0 mg.g-1,效果较好;微波渗糖时采用30%的微波火力渗糖20 min,后期干燥时选用60℃干燥6 h,与其他处理差异显著,果脯口感纯正,可以使多维营养得到最大程度的保存。     

杨梅果肉维生素C含量测定法评价

杨梅作为我国南方著名的特色水果,口味好,风味独特,在果实品质研究中维生素C含量的测定是必不可少的.维生素C（简称Vc）又叫抗坏血酸,是一种已糖衍生物,包括还原型Vc和氧化型Vc两种,以前新鲜果品中以测定还原型Vc为主.现有的Vc测定方法主要是全量测定法（测定还原型和氧化型Vc的总含量）如国标荧光法,2,4-二硝基苯肼法）和还原型Vc测定法（2,6-二氯靛酚滴定法、碘滴定法、钼蓝比色法、碘酸钾萃取分光光度法、原子吸收测定法、荧光法、色谱法等）两大类.有些方法既可测定全量,也可测定还原型Vc,如酶法,但目前这样的方法相对较少.尽管测定Vc方法很多,但在我国特色水果杨梅Vc的具体测定过程中,问题不少,还是没有简单满意的检测方法.下面就杨梅果肉VC测定过程中应用的几种测试方法简单作个评价.     

果品维生素C含量测定中的几个问题

维生素Ｃ(以下简称Ｖｃ),又叫抗坏血酸,是一种己糖衍生物。在果树种质资源研究、品种育种、贮藏加工和果品质量监测中,经常需要测定Ｖｃ含量。Ｖｃ分析方法的研究一直很活跃,在果品研究有关文章中已有大量报道[1～11]。但在实际工作中,果品Ｖｃ含量的测定还应注意下面几个问题。1　测定方法Ｖｃ包括还原型Ｖｃ和氧化型Ｖｃ两种,新鲜果品中以还原型Ｖｃ为主[1]。现有的Ｖｃ测定方法主要是全量测定法(测定还原型Ｖｃ和氧化型Ｖｃ的总含量。如文献[2]方法、荧光法[3]、2,4二硝基苯肼法[4]等)和还原型Ｖｃ测定法(如文献[5]方法、2,6二氯靛酚滴定…     

新鲜果蔬维生素C测定方法

水果和蔬菜是重要的维生素C(Vc)源,因此,Vc定量在水果蔬菜营养分析中占据重要位置。Vc是由L—抗坏血酸(还原型,简称AsA)、D—抗坏血酸(脱氢型,简称DAsA)及二酮古乐糖酸(DKG)组成。后者无生物活性。AsA+DAsA占新鲜植物体内Vc总量的90％以     

野生玫瑰果还原型维生素C含量及影响因素的研究

该文以野生玫瑰果为试验材料,研究不同品系、不同采果期、不同栽培条件和贮存时间对还原型维生素C含量的影响。试验表明:4个不同品系在同一采果日还原型维生素C含量差异较大,7月末之前C品系显著高于其他3个品系;4个不同品系还原型维生素C含量都在7月10日最高,随着果实成熟均呈下降趋势;7月末之前下降速度较快,以后趋于平稳。A品系在稀植条件下还原型维生素C含量显著高于密植的。以测定还原型维生素C含量为目的时果实在-70℃冰箱中贮存不应超过4个月。     

青椒（维生素C宝库）

青椒含有丰富的维生素C和维生素A，两者的含量均随其成熟程度而增加。青椒中维生素C的含量是西红柿的几倍，与草莓和柠檬的含量差不多。其富含的维生素C、维生素K，可以防治坏血病，对牙龈出血、贫血、血管脆弱有较好的辅助治疗作用。同时，青椒特有的清香味道和所含的辣椒素有刺激唾液分泌的作用，能增进食欲，帮助消化，促进肠蠕动，防止便秘。此外，青椒有温中下气、散寒除湿的作用，     

一氧化氮处理对韭菜维生素C含量的影响

以地产农家新鲜韭菜为试材,研究了常温、常压下用硝普钠溶液处理对韭菜贮藏保鲜效果的影响。结果表明:选择不同浓度的硝普纳(SNP)溶液,处理韭菜时间的长短对其保鲜效果的影响各不相同,1.0μmol/L SNP、浸泡1.5h对延缓维生素C含量下降的作用最大。说明适宜浓度外源NO处理能够降低延缓芹菜氧化衰老进程,对采后芹菜有显著的保鲜效果。     

维生素C及衍生物的稳定性分析

本研究分析了光照、空气、温度和储藏时间对市场上8种常见维生素C原料稳定性的影响。结果表明，8种维生素C在日光、紫外光照射及避光条件下6 h后保留率在95%左右；在密封条件下加热处理时，维生素C的降解较慢，而当样品与空气接触时，其降解加快，随温度增高而加快；在有氧条件下，当温度升高至50℃及以上时，所有样品降解明显。比较热及储藏稳定性发现，乙基醚维生素C具有最高的稳定性，维生素C、100目维生素C、复配维生素C和96%颗粒维生素C次之，维生素C钠、复配维生素C钠和维生素C钙具有最低的热和储藏稳定性。研究结果将为果蔬保鲜及和维生素C稳定化提供理论参考。     

枣品种果实维生素C含量变化的研究

枣果实的含糖量(鲜枣18.68—35.28%)不但在各种水果中是最高者之一,而且其维生素 C(V—C)含量也是最高者之一,所以枣果实被称为“活维生素丸”。1987—1989年,我们对121份鲜枣果实、94份干枣果实维生素 C 含量进行了测定。根据三年测定结果,对维生素 C 含量进行了分级,并对其果实发育期维生素 C 含量动态进行了研究。     

干制苹果片无硫复合护色液的优化配制

以苹果为试材,选用氯化钠、氯化钙、柠檬酸、EDTA-2Na、异抗坏血酸钠为试剂,采用响应面法对苹果片干制过程中的褐变进行了护色研究。结果表明:氯化钠1.05%、氯化钙0.63%、柠檬酸0.94%、EDTA-2Na 0.16%、异抗坏血酸钠1.65%为最优护色工艺参数。     

Physico-chemical properties and antioxidant capacity of different jujube (Ziziphus jujuba Mill.) cultivars grown in loess plateau of China

The physico-chemical properties and antioxidant capacity of the five main jujube varieties: Junzao, Lingbaozao, Jinzao, Zanhuangzao and Lizao collected from loess plateau of China were determined. The analyzed components included fruit yield, moisture content, total mass per fruit, pH, titratable acidity (TA), reducing sugars, total sugars, total soluble solids (TSS), ascorbic acid, total phenolics content, total flavonoids content and several pure phenolic compounds. The output of the analyses showed higher amounts of ascorbic acid and phenolics in these jujube varieties than in some common fruits. The antioxidative capacity of the jujube extracts, evaluated with the reducing power, the β-carotene bleaching, the 2,2-diphenyl-1-picrylhydracyl (DPPH•), and the 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonicacid) (ABTS•⁺) scavenging methods, showed that the antioxidant activity of the extracts of Lingbaozao was excellent for free radical scavenging and a potent natural antioxidant of commercial value. Statistically significant differences were observed between jujube cultivars investigated with regards to the measured parameters except rutin content of fruit. These results demonstrated that the cultivar was the main factor which influences the physico-chemical properties and antioxidant activity of jujubes.     

大果优质南酸枣新株系‘南酸枣3号’选育研究

‘南酸枣3号’是从福建省福州市闽侯县南酸枣实生株中选育出的新株系。果实广椭圆形，未成熟时果皮绿色，成熟后果皮金黄色，果大且外观好，果肉白色，粘糊状。丰产，10年生树株产130kg。平均单果重18．5g，果实纵横径3．3cm×3．0cm，可食率64．9％。果实主要营养成分含量为可溶性固形物7．9％、总糖6．8％、可滴定酸4．3％、维生素C74．0mg·（100g）-1、总果胶3．3％、水溶性果胶2．5％。     

Inter-Relations of Hesperidin,Some other Natural Components and Certain Enzyme Systems in Developing Shamouti Orange Fruits

The relationships of a large number of components and enzyme systems of the Shamouti orange fruit have been studied during the growth period extending from April to December. Data have been evaluated with the help of an electronic computer.

Early in July, towards the end of the first period of growth, peel thickness attains its maximum, cell divisions almost cease, growth of internal fruit parts (endocarp) begins and many fruit components (as ascorbic and dehydroascorbic acids and the bioflavanoid hesperidin) and many enzymic systems (as peroxidase, catalase, indole acetic acid oxidase and ascorbic acid oxidase) attain their maximum values and activities when expressed on a total nitrogen basis. This points to higher metabolic activity of tissues during the first period of growth.

During the second period (July to December) concentrations and activities of components decrease, relative to fresh and dry weight and to total nitrogen, partly because of dilution by inert cellular components and partly through decreasing metabolic activity. Only by expressing results on a per fruit basis (because of the large increase in volume of individual fruits) do the values of some components, especially reducing sugars and catalase activity, continue to increase.

The ascorbic acid system, hesperidin, and enzymes effective in oxidation of ascorbic acid, in degradation of the growth hormone indole-3-acetic acid and otherwise active in oxido-reduction reactions are interrelated' both when the curves are compared and after the time effect has been removed. This suggests that these systems are interrelated irrespective of the age of the fruit.     

H2O2诱导低温胁迫下草莓苗抗冷性研究

以草莓品种“丰香”为试材,研究了在低温胁迫下叶面喷施低浓度H2O2后草莓相关抗逆性生理指标的特性.结果表明:不同浓度H2O2处理抑制低温胁迫草莓叶细胞电解质渗透率和丙二醛(MDA)含量的增加,增强了草莓叶细胞内超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和谷胱甘肽还原酶(GR)的活性.     

红枣多糖在加工过程中的变化研究

本文研究了红枣多糖在红枣清汁加工过程中的变化,分析了不同加工工艺、不同果浆酶以及不同澄清剂对枣汁的处理效果。实验结果表明,酶解可提高红枣多糖含量,经澄清、超滤、吸附后红枣多糖含量明显降低。因此对酶解工艺和澄清工艺进行优化,筛选出果浆酶PECTINEX SMASH XXL能提高多糖含量和出汁率,采用复合澄清剂能提高枣汁稳定性,但不能提高枣汁多糖含量。     

酶法脱酯从柚皮中制取低甲氧基果胶的工艺研究

以新鲜柚皮为原料,添加碳酸钠激活内源果胶酯酶制备低甲氧基果胶。以果胶甲氧基含量和得率为指标,通过正交实验优化酶法脱酯及酸提取的工艺条件,确定最优低甲氧基果胶制备工艺。结果表明:加入果皮浆液量0.15%的果胶酯酶激活剂碳酸钠,在pH 7.5、45℃的下脱酯50 min,然后采用85℃p、H 3.56、0 min进行酸水解提取果胶。在此工艺条件下制备的果胶甲氧基含量为5.9%,符合低甲氧基果胶标准,且果胶得率较高,为3.0%。     

Growth and ripening season effects on antioxidant capacity of strawberry cultivar Selva

There is wide awareness on the importance of antioxidants in cell protection against free radicals constantly produced by the cell metabolism. In this work, carried out with strawberry cultivar “Selva”, the antioxidant capacity and content of the main accepted antioxidants – ascorbic acid, dehydroascorbic acid, total phenols and anthocyanins – were determined along 10 growth stages of the fruit. Strawberries were harvested in winter and summer. Minimum/maximum temperatures in the two seasons were 6.3 °C/14.9 °C and 14.5 °C/27.8 °C, respectively. Antioxidant capacity in the small green stage was 27 mmol DPPH/100 g fresh tissue, keeping noticeably high values in the large-green one. Towards the white stage, antioxidant capacity reduced, to remain mostly constant. The antioxidant capacity was higher in those stages where cell division was more important and this parameter correlated mostly with the contents of total phenols and ascorbic acid.     

Physiological Studies During the Growth and Development of Different Varieties of Guavas (Psidium Guajava L.)

In a study of three seed-bearing varieties of guava and one seedless variety changes in size and specific gravity and in the content of water, titratable acid, reducing and non-reducing sugars, tannins, pectin, and ascorbic acid were recorded at intervals from fruit-set to harvest. Respiration rates were also determined during this period.

Patterns of change were generally similar in seeded and unseeded varieties, though the sugars and ascorbic acid contents rose earlier and to higher levels in the seedless than in the seeded, and the fruits matured and fell from the trees earlier.

Increasing ascorbic acid content, concurrent with declining pectin content in the seeded varieties, is consistent with the hypothesis that pectin degradation and ascorbic acid are linked, but in the seedless variety a rapid rise in the ascorbic acid content occurred during a period of pectin accumulation. The end of the initial rapid decline in respiration rate generally coincided with the beginning of reducing-sugar accumulation.