水果还原型VC和氧化型VC的含量及稳定性研究

分析测定了常见水果的还原型VC（Ascorbic acid, AA）与氧化型VC（Dehydroascorbic acid, DHA）的含量，并研究了空气和热处理对其AA与DHA含量的影响。结果表明，不同的水果种类，其AA与DHA含量有较大差异，除大枣以外，富含AA的水果，其DHA占总VC的比例大，AA含量低的水果，其DHA占总VC的比例小；水果破碎后与空气接触能够明显降低水果AA含量，增加其DHA含量；加热时间对水果AA含量有极显著的影响，但加热温度对不同水果有不同的影响，不同的水果种类，其DHA对加热温度和时间的反应不同。     

Preharvest and postharvest factors related to off-odours of fresh-cut iceberg lettuce

The influence of different preharvest and postharvest factors affecting off-odour development of fresh-cut iceberg lettuce in low-O₂ modified atmospheres (MA) was investigated. Fresh-cut iceberg lettuce developed undesirable off-odours under low O₂ and elevated CO₂ atmospheres. A strong relationship between CO₂ concentration and off-odour development was observed. Significant differences in off-odour development existed among different cultivars in two harvests in consecutive years. The influence of maturity stage was evaluated, comparing fresh-cut product from immature and over-mature heads with commercial ones. Higher CO₂ concentrations and higher accumulation of ethanol and acetaldehyde were detected in the headspace of MA-packed lettuce from immature heads. Differences in respiration rate of the fresh-cut product from heads cultivated during the winter–spring seasons were around 30%. Respiration rate of fresh-cut iceberg lettuce increased when medium temperature during cultivation increased. Changes in the product weight generated different CO₂ levels which correlated with the production of ethanol and acetaldehyde and other off-odour metabolites related with the lipoxygenase (LOX) pathway such as hexanal, 1-hexanol, and cis-3-hexen-1-ol. Volatile compounds such as cis-3-hexen-1-ol, β-elemene, ethyl acetate and dimethyl sulphide increased their content more than 10 times compared with other volatiles. Moreover, differences in the initial flushed gas-mixture with or without CO₂ showed higher CO₂ concentrations and the development of stronger off-odours when samples were flushed with an enriched CO₂ gas-mixture. In summary, visual quality of fresh-cut iceberg lettuce is important but so are odour and flavour. MAP currently used for fresh-cut lettuce may need some modification to inhibit off-odours and achieve better aroma and flavour qualities for preserving “freshness” of the cut product. Screening for cultivars with low browning potential and fermentation, harvested at optimum maturity stage and with an adequate package design are recommended.     

植酸对控制打浆中水果Vc损失的效应

研究了植酸对控制草莓、猕猴桃和山楂果实打浆工序中 Vc损失的效应。结果表明，植酸对三种水果打浆工序中还原型Vc（AA）和氧化型Vc（DHA）的保护效果不一，植酸可以明显提高山楂打浆中的AA和DHA保存率；对猕猴桃仅提高其DHA保存率，不能提高AA保存率。对草莓AA和DHA的保存效果则与猕猴桃相反。     

A rapid colorimetric method for screening black currant juices for vitamin C content

Summary A rapid laboratory method was developed for screening black currant juices for ascorbic acid content in a plant breeding programme.     

Vitamin C in broccoli (Brassica oleracea L. var. italica) flower buds as affected by postharvest light,UV-B irradiation and temperature

In this study, the changes in vitamin C, l-ascorbic acid (AA) and l-dehydroascorbic acid (DHA) levels in broccoli flower buds were examined during pre-storage and storage periods, simulating refrigerated transport with wholesale distribution and retail, respectively. Broccoli heads were pre-stored for 4 or 7 days at 0 °C or 4 °C in the dark and then stored for 3 days at 10 °C or 18 °C. During storage the broccoli heads were exposed for 12 h per day to three different levels of visible light (13, 19 or 25 μmol m⁻² s⁻¹) or a combination of visible light (19 μmol m⁻² s⁻¹) and UV-B irradiation (20 kJ m⁻² d⁻¹), or they were stored in the dark. The vitamin C content in broccoli flower buds during storage was significantly affected by pre-storage period and temperature. Higher vitamin C levels in flower buds after storage were observed for broccoli heads pre-stored for 4 days or at 0 °C as compared to those pre-stored for 7 days or at 4 °C. Storage temperature also affected vitamin C in broccoli flower buds, with higher levels observed for broccoli stored at 10 °C than at 18 °C. Hence, vitamin C in broccoli flower buds was demonstrated to decrease together with increasing pre-storage period, pre-storage temperature and storage temperature. AA in broccoli flower buds was influenced mainly by storage temperature and to a minor extent by pre-storage temperature. The DHA level and DHA/AA ratio were stable in flower buds of broccoli pre-stored for 7 days, whereas increasing tendencies for both DHA level and ratio were observed after pre-storage for 4 days. These results indicate a shift in the ascorbate metabolism in broccoli flower buds during storage at low temperatures, with its higher rate observed for broccoli pre-stored for shorter time. There were no effects of the light and UV-B irradiation treatments on vitamin C, AA and DHA levels in broccoli flower buds.     

农作物新品种新技术的微观需求及影响因素分析——以油菜为例

基于我国主要油菜种植区600个农户的调查数据,通过统计分析,得出以下结论:农户普遍重视油菜新品种的潜在产量和抗性,认为现场示范和定期咨询的技术推广方式效果最佳。通过交叉表分析得出:年龄在50~60岁之间、户种植规模在1334m2以下和家庭收入处于中等水平的油菜种植户接受新品种新技术的积极性较强。油菜新品种新技术研发及推广部门可参照这些依据,采取针对性的改进措施推进油菜产业的发展。     

心里美萝卜维生素C与花青苷的相关分析

对65份心里美萝卜的维生素C与花青苷进行相关分析,结果表明,心里美萝卜维生素C含量与花青苷含量呈极显著相关(r=0.3654,P<0.01);回归处理后,得线性方程式:Y=17.06+7.31X,回归关系达极显著水平(F=9.6460,P<0.01).此结果说明由花青苷含量(X)估计维生素C含量(Y)有一定的可靠性.     

辣椒果实维生素C含量性状的遗传分析

为了解辣椒果实中维生素C(Vc)含量的遗传规律,对辣椒果实Vc含量进行遗传分析。选用Vc含量差异显著的‘L5’(高Vc含量)和‘L158’(低Vc含量)2个品种分别作为杂交的母本和父本,从而构建了3种世代群体。同时测定和分析辣椒果实Vc含量及与其他果实相关性状的相关性。结果表明:果实中Vc含量呈连续性变化趋势,受多基因控制。Vc含量与单果平均重呈显著正相关,与果肉厚呈显著负相关。Vc含量与可溶性固形物、果横径、果纵径不相关。辣椒Vc含量属于数量性状,受控于多个基因,属于C-O模型,即加性-显性-上位性多基因混合遗传模型。     

中华猕猴桃‘金阳’果实生长发育动态分析

研究南京地区‘金阳’猕猴桃果实发育规律,为其在南京及其周边地区的推广及优质丰产提供理论依据。以5年生‘金阳’猕猴桃为试验材料,定期观察并记录‘金阳’猕猴桃从坐果到成熟软化过程中的鲜重、干重、纵横径、种子发育和果肉颜色等形态指标,并测定可溶性固形物、可溶性糖、可滴定酸、有机酸、维生素C、叶绿素和类胡萝卜素等含量。结果表明,‘金阳’猕猴桃花后0～40 d果实迅速膨大,鲜重快速增加;花后20～116 d干物质不断积累;花后83 d种子开始变黑,花后97 d种子完全变黑成熟。‘金阳’果实成熟前,可溶性固形物变化幅度较小,可溶性糖含量呈上升趋势,维生素C和可滴定酸均呈先上升后下降的趋势,有机酸中奎宁酸、苹果酸、柠檬酸的含量较高。‘金阳’花后138～154 d,果实达到可采收状态。果实采收后,硬度迅速下降,并且类胡萝卜素/叶绿素的比值升高,果肉颜色由绿色转为黄绿色,再变为黄色。南京地区可食用状态下‘金阳’猕猴桃单果重为80.5 g,果肉金黄色,维生素C的含量为129 mg/100 g,可溶性固形物的含量为14%,可滴定酸的含量为1.4%,果实经济性状良好,因此‘金阳’猕猴桃适宜在南京地区推广。     

鲜枣贮藏过程中维生素C含量变化规律的研究

鲜枣贮藏过程中维生素Ｃ含量先下降,后略上升又下降;不同品种、不同成熟度、不同采后处理方法,对贮藏过程中维生素Ｃ含量变化规律的影响不同,速冻和热处理对Ｖｃ有破坏作用。脆果率高、贮藏效果好的处理维生素Ｃ含量也高,因此鲜枣贮藏过程中脆果率的高低可作为维生素Ｃ保存效果的指标。     

铅与维生素C对小鼠肝脏脂质过氧化的影响

以五周龄昆白系小鼠为试验动物,在饲喂小鼠普通日粮基础上每天灌喂一定量铅（Pb）、维生素C（Vc）、Vc+Pb,Vc用量200mg/kg,Pb四个浓度分别为1.2g/L 、0.4g/L、0.13g/L、0.043g/L,饲喂期三周,检测小鼠肝脏中铅与丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性变化。结果表明：铅在小鼠肝脏中大量蓄集,并引起MDA含量增加;加Pb组与空白对照组相比SOD酶活性降低,且随着铅浓度的降低而升高;CAT活性测定显示： Pb1、Pb2组与空白对照组相比差异显著（p<0.05）,Pb3组差异极显著(p<0.01),除Vc+Pb4组与Pb4组相比差异不显著(P>0.05)外,其他Vc+Pb组与其对应加Pb组比较,均差异显著（p<0.05）;POD活性测定表明：Vc组与空白组相比差异极显著(p<0.01),Pb1、Pb3组与空白组比较差异显著（p<0.05）,Pb2、Pb4与空白组比较差异极显著(p<0.01),除Vc+Pb1组与Pb1组差异不显著(P>0.05),其他Vc加Pb组与单独加Pb组相比差异极显著(p<0.01)。因此,Pb可增强小鼠肝脏脂质过氧化,而Vc可减轻铅引起的过氧化损伤     

Baby-leaf and multi-leaf of green and red lettuces are suitable raw materials for the fresh-cut industry

Consumer demand for softer leaves with variation in taste, shape and colours has encouraged the development of new lettuce products of baby-sized leaves. The objective of this study was the comparison of whole-head lettuce, as the most common raw material for fresh-cut, with baby-leaf and multi-leaf as the newest baby-sized lettuce leaves. Lettuces (Lactuca sativa L.) of the types Green Leaf, Red Leaf and Lollo Rosso were cultivated in the same field with different plant densities, under commercial conditions. Although baby-leaf was subjected to far less wound damage than the shredded lettuce from the whole-head, leaf age could play an important role in increasing respiration rate and determining postharvest quality. After 9-11 d of storage, minimally processed products from the three types of raw material showed good visual quality without differences among them. However, over the 12-d storage period, quality decreased to the limit of marketability mainly due to browning of the cut edge surface of the fresh-cut product from whole-heads and decay due to the soft tissue in the case of baby-leaves. Additionally, with the processing of whole-heads, the increase in cut-damage surfaces and availability of cell nutrients provided conditions that favoured the growth of lactic acid bacteria (LAB) and total coliforms compared to uncut surfaces of baby-sized leaves. The ratio between the oxidized and reduced forms of ascorbate (DHA/AA) increased 2-4 times after 9-11 d of storage. Furthermore, baby-sized leaves had higher phenolic contents than the shredded product from the whole-head which probably contributed to reaching a shelf-life of 11 d. In conclusion, the new green and red baby-sized leaves both at immature and mature stages provided high quality lettuce for the fresh-cut market, meeting specific requirements regarding visual quality, microbial load and high content of phytochemicals.     

Plant genetic resources of Nepal: A guide for plant breeders of agricultural, horticultural and forestry crops

Summary Nepal is rich in indigenous wild and landrace plant genetic resources for agronomic, horticultural, forestry, or medicinal uses, but much of this germplasm remains uncollected and awaits economic development. We list 485 entries (species, or genera for ornamental plants) in 14 categories, and compare these to existing germplasm collections in Nepal and the United States to highlight collection and conservation needs. To help plant plant collecting, we outline the key botanical and logistical data and legal framework for planning field work in Nepal.     

检测草莓果中多组分的新方法——近红外光谱法

用近红外光谱法（ＮＩＲｓ）分析草莓中的蔗糖、葡萄糖、果糖、柠檬酸、苹果酸和维生素Ｃ等６种成分，与高效液相色谱法（ＨＰＬＣ）有测值相比较，其相关系数分别为０．９９２０、０．９９１４、０．９８８８．０．９９５４．０。９９４９和０．９９８０，标准误差为０．０２１、０．０３５、０．０６５、０．０４４、０．０２９．０。７２７。说明ＮＩＲｓ法与ＨＰＬＣ法的准确度相似。由于此法具有快速、非破坏、样品不需要预处理     

不同产地谷子籽粒营养品质与食味品质的比较研究

为了在现有谷子品种的基础上,明确有利于提高谷子籽粒营养品质和食味品质的生长环境,本文对‘长农38号’、‘长农39号’、‘长农41号’谷子在长治和沁县两个生态点谷子籽粒的营养品质与食味品质进行比较分析。结果表明:种植地区对‘长农38号’谷子籽粒的维生素B1、直链淀粉、粗蛋白和‘长农41号’的维生素B1、粗脂肪的影响较大,变异系数均在10%以上;对‘长农39号’谷子籽粒的营养品质影响较小,变异系数均在10%以下。通过食味品质的比较可以看出种植在沁县的‘长农38号’谷子籽粒的一致性高于长治,种植在长治的‘长农39号’、‘长农41号’谷子籽粒的一致性低于沁县;种植于长治的‘长农38号’、‘长农39号’谷子籽粒的色泽高于沁县,种植于长治的‘长农41号’谷子籽粒色泽与沁县的评分结果一样;种植于沁县的3个基因型谷子籽粒食味品质的分数合计结果均高于长治。因此通过优化谷子栽培管理措施对提高谷子籽粒品质具有重要意义。     

四十种瓜菜中超氧化物歧化酶含量测定

采用化学发光法测定了40种蔬菜、瓜、果中的超氧化物歧化酶(SOD)的含量,并在此基础上探讨了9种蔬菜中维生素E、C、蛋白对SOD的影响以及它们之间的关系.还观察了蔬菜中SOD的热稳定性.结果表明,不同蔬菜、瓜、果间SOD含量的差异很大,其范围在1.26～176.10×10~(-3)g/g蛋白之间;去除脂溶性维生素E时SOD有不同程度的下降;维生素C及蛋白与SOD无明显对应关系;加热处理后样品的SOD仍得到较好保存.     

不结球白菜维生素C含量主基因+多基因遗传分析

以高维生素C含量不结球白菜自交系乌塌菜和低维生素C含量不结球白菜自交系二青杂交获得的6个世代(P₁、P₂、F₁、B₁、B₂和F₂)株系为材料, 应用植物数量性状主基因+多基因混合遗传模型, 对不结球白菜中维生素C含量进行遗传分析。结果显示, 不结球白菜中维生素C含量受1对加性主基因+加性-显性多基因控制, 其中2011年结果中, 主基因的加性效应为13.15, 在B₁、B₂、F₂世代中主基因的遗传率分别为54.38%、38.58%和18.69%, 多基因的遗传率分别为24.69%、36.92%和40.7%; 2013年结果中, 主基因的加性效应为6.04, 在B₁、B₂、F₂世代中主基因的遗传率分别为1.88%、6.41%和45.04%, 多基因的遗传率分别为39.67%、16.57%和16.91%。可见, 不结球白菜维生素C性状受环境影响较大, 在不结球白菜高维生素C含量品种选育过程中, 要注重环境影响, 并可以通过分子标记辅助选择, 对性状进行改良。     

Preharvest application of methyl jasmonate (MeJA) in two plum cultivars. 2. Improvement of fruit quality and antioxidant systems during postharvest storage

‘Black Splendor’ (BS) and ‘Royal Rosa’ (RR) plums were treated preharvest with methyl jasmonate (MeJA) at three concentrations (0.5, 1.0 and 2.0 mM) along the on-tree fruit development: 63, 77 and 98 days after full blossom (DAFB). Both control and treated fruit were harvested at the commercial ripening stage and stored in two temperature conditions: 9 days at 20 °C or at 2 °C + 1 day at 20 °C for 50 days. Preharvest MeJA at 2.0 mM significantly accelerated whereas 0.5 mM delayed the postharvest ripening process for both cultivars, since ethylene production, respiration rate and softening were reduced significantly at the two storage conditions for 0.5 mM. In these fruit, total phenolics, total antioxidant activity (hydrophilic fraction, HTAA) and the antioxidant enzymes peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were found at higher levels in treated than control plums during postharvest storage, which could account for the delay of the postharvest ripening process and the extension of shelf-life.     

彩色小麦近等基因系籽粒中氨基酸含量的比较分析

氨基酸是蛋白质的基本组成单位,是人体必需的重要营养物质。彩色小麦被认为是一类新型的营养保健小麦品种,但对其籽粒中氨基酸含量的研究很少。本研究首次利用高效液相色谱法比较分析了种植于三个环境中的彩色小麦近等基因系(蓝粒小麦科兴611,紫粒小麦科兴617和白粒小麦轮回亲本济麦22)籽粒中多种氨基酸的含量。结果表明,蓝粒小麦科兴611的必需氨基酸含量、非必需氨基酸含量及总氨基酸含量均显著地高于紫粒小麦科兴617和白粒亲本济麦22。紫粒小麦科兴617和白粒小麦济麦22相比,必需氨基酸含量、非必需氨基酸含量及总氨基酸含量相近,甚至低于济麦22。因此,蓝粒小麦籽粒氨基酸含量高的性状,有益于满足人类营养需求,同时可作为育种材料改良小麦品种的氨基酸含量,尤其是提高限制性氨基酸的含量,进而提高小麦的营养品质。     

采前氯化钙和水杨酸处理对蟠枣采后贮藏品质的影响

为探究采前处理对蟠枣果实采后贮藏品质的影响,以新疆主栽鲜食品种蟠枣为研究对象,分别于果实花期、幼果期、膨大期、着色期采用清水(CK)、10 g/L氯化钙(CaCl₂)、100 mmol/L水杨酸(SA)和10 g/L CaCl₂+100 mmol/L SA进行采前喷施处理,采收后置于常温货架贮藏,每天统计果实的转红率、转红指数、腐烂率和失重率,测定果实的可溶性固形物含量、硬度和色泽等指标。结果表明：采前喷施CaCl₂、SA和CaCl₂+SA均可一定程度上抑制蟠枣的转红和腐烂,使其保持较低的失重率,使果实维持较高的可溶性固形物含量和硬度,保持较好的色泽,其中,10 g/L CaCl₂+100 mmol/L SA采前处理效果最佳,常温货架8 d时,果实的转红率和腐烂率分别较对照低23.34个百分点和36.66个百分点,失重率仅为1.68%,果实可溶性固形物含量维持在21.47%,硬度为9.45 kg/cm²,保持较好的商品性。综上,采前喷施10 g/L CaC...