The non-volatile organic acids of the differently coloured areas of the walls of 'blotchy' ripened tomatoes

A comparative study has been made of the individual non-volatile organic acids in ethanolic extracts of the red and green areas of the walls of tomato fruit showing symptoms of ‘blotchy’ ripening. The titratable and total acidites of the green areas were lower, and the combined acidity higher than those of the red areas. Potassium concentrations in the differently coloured areas did not differ significantly. Concentrations of the dicarboxylic amino-acids, pyrrolidonecarboxylic, malic and citric acids in the green areas were all significantly lower than in the corresponding red areas. Citric acid concentrations were much lower and glutamic acid concentrations higher than those found previously in the walls of uniformly ripened fruit of similar colours. The malic/citric acid ratio in the green areas was approximately double that in the red areas. In both cases values were greater than those normally encountered in evenly ripening fruit. The proportions of the total acidity present as malic acid in the differently coloured areas was strikingly similar to that found in the walls of normally ripened fruit of the same colour and variety. On the other hand the proportion of citric acid was markedly reduced in the ‘blotchy’ fruit walls. It is suggested that low citric acid concentrations combined with the persistence of high polyphenol-oxidase activity may be conducive to ‘blotchy’ ripening of tomato fruit.     

福建省4 个果梅主栽品种果实营养品质、香气成分分析与评价

以福建省4 个果梅主栽品种青竹梅、龙眼梅、杭梅和白粉梅为试材,分析测定果实的主要性状和营养成分,包括单果质量、果实大小、VC、总酚、类黄酮、可溶性糖、有机酸、香气组分以及矿质元素含量。结果表明,4 个果梅品种VC、总酚、类黄酮、可溶性糖、有机酸、香气组分以及矿质元素含量存在显著差异。果梅主要可溶性糖为蔗糖,其次为葡萄糖和果糖;主要有机酸为柠檬酸,其次为苹果酸、琥珀酸、乙酸和奎宁酸;4 个果梅品种果实共检测出110 种挥发性物质,包括30 种酯类、26 种醇类、17 种醛类、15 种酮类、7 种酸类以及15 种其他类,其中有26 种物质为4 个品种共有成分,2-己烯醛、己醛、己醇和反式-罗勒烯醇可能是果梅特征香气的重要物质;4 个果梅品种含有较高的K、Ca和Se含量。通过主成分分析提取,得出综合得分品种最高为青竹梅,青竹梅果实挥发性物质相对总含量高于其他3 个品种且综合品质最佳,适宜作为选育果梅良种的育种材料。本研究结果为明确果梅营养价值评价及其在良种选育、生产加工中的合理利用提供理论依据。     

Organic acids of various kinds of vegetables. IV. Changes in the acids and sugar in tomatoes, sweet peppers and cucumbers during development and ripening

Concentrations of organic acids and sugars in tomatoes and sweet peppers change notably during ripening. The concentration of malic acid decreases while that of citric acid increases considerably and in redripe fruits clearly exceeds the content of malic acid. Several maxima and minima in acid concentrations occur during development. Both species show constant proportions of citric and isocitric acid (200:1 and 30:1 respectively). In sweet pepper, quinic and ascorbic acid can be found in noticeably higher amounts than in tomatoes. Additionally, succinic acid was detected in tomatoes and fumaric and shikimic acid in sweet pepper. Glucose and fructose, in approximately equal amounts, are the main sugar components; their concentrations are increased during ripening, especially in sweet peppers. The leaves of tomatoes and sweet pepper contain more malic acid and less citric acid than redripe fruits, though here as well citric acid predominates. There is considerably less glucose and fructose present in the leaves of sweet pepper than in the fruits while sucrose is increased. Sucrose is the main sugar component in the leaves. Compared to tomatoes and sweet peppers, egg-plants contain more amounts. - Potatoes contain citric, malic, quinic, succinic, fumaric, and soluble oxalic acid (in order of decreasing amounts). - In cucumbers malic acid notably exceeds citric acid. Both acids hardly change in concentration during ripening. Sugar content decreases during ripening.     

Evaluation of peach and nectarine fruit quality and correlations between sensory and chemical attributes

Sensory attributes and chemical composition in peach and nectarine fruits of nine different cultivars were evaluated and compared. The cultivars investigated in the research were: ‘Maria Marta’, ‘Romestar’, ‘325 × A/8’, ‘224 × A/13’, ‘V × S/4’, ‘Bea’, ‘Maria Aurelia’, ‘Venus’ and ‘Spring Red’. In sensory evaluation the ‘Maria Aurelia’ was the highest rated, and the ‘224 × A/13’ was the lowest. The cultivars ‘325 × A/8’, ‘224 × A/13’, ‘V × S/4’ and ‘Spring Red’ were poor in sugars; however, the ‘Spring Red’ was rich in organic acids. Similarly, the ‘Maria Aurelia’ and ‘Venus’ fruits had higher contents of organic acids and were also rich in sugars. Furthermore, the relationships among sensory and chemical attributes of fruit quality were studied. The sensory evaluations of sweetness, taste, and aroma were well correlated with some chemically measured attributes of peach and nectarine quality: sweetness was influenced by citric acid, shikimic acid and sugars/organic acids ratio; aroma was correlated with total organic acids, sucrose, sorbitol and malic acid; taste was related to malic/citric acid ratio, total sugars, sucrose, sorbitol and malic acid. The results of the research indicate that sensory evaluation provides a good tool in the quick assessment of peach and nectarine fruit quality. Copyright © 2005 Society of Chemical Industry     

江津甜橙3个变异品种的果实品质及酸组分分析

以江津甜橙的优选品种锦橙及其低酸变异品种长叶橙和高酸大果芽变品种大果锦橙为试材,测定果实膨大至成熟期的多项品质指标及其果汁中柠檬酸、奎宁酸和苹果酸含量的变化趋势。结果表明,在果实发育过程中,各品种果实大小于10月下旬基本定型,可溶性固形物含量逐渐增加、可滴定酸含量逐渐下降。在所测酸组分中,柠檬酸为主要有机酸;在果实发育过程中,柠檬酸含量逐渐降低,苹果酸含量呈相反的变化趋势,奎宁酸含量呈先下降后上升再下降的趋势,最大值出现在11月中旬。在果实成熟阶段,锦橙平均单果质量和柠檬酸含量介于长叶橙和大果锦橙之间,可溶性固形物含量为最高;长叶橙单果质量最小(155.27 g),可滴定酸含量最低(0.55%),其中柠檬酸组分含量为6.95 mg/g;大果锦橙则相反,单果质量达311.92 g,可滴定酸含量为1.02%,其中柠檬酸含量为11.72 mg/g。3个品种总体上呈酸度越高,柠檬酸含量越高,奎宁酸含量越低的趋势。     

桑葚果实不同发育期品质测定及其相关性分析

本研究对湛江地区7个桑葚品种青果期、转色期、成熟期三个时期桑葚果的单果重、可溶性固形物、可滴定酸含量及糖和有机酸组成和含量进行了测定,并进行了相关性分析。结果表明,在成熟过程中桑葚果实的可溶性固形物和糖含量呈增加的趋势,而酸则呈降低的趋势;在桑葚果实品种中检测出柠檬酸、苹果酸、奎宁酸、琥珀酸、酒石酸、酮戊二酸、抗坏血酸、草酸共8种有机酸,其中柠檬酸的含量最高,其在不同品种不同发育期含量为44.84%~80.86%,其次为奎宁酸和苹果酸;果糖和葡萄糖是桑葚重要的糖组成,其含量在成熟期的台湾长果桑的含量分别达到57.79 mg/g和66.72 mg/g,并且只有在台湾长果桑中检测到蔗糖;通过相关性分析,可滴定酸与可溶性固形物、果糖、葡萄糖、果重呈负相关,且可溶性固形物、果糖含量、葡萄糖含量三者之间呈极正相关。     

基于UPLC-MS/MS探究烘焙程度对咖啡豆中有机酸含量影响

为探究烘焙工艺对咖啡豆口感的影响,本文研究了烘焙程度对咖啡豆中有机酸含量的影响。采用新建立超高效液质联用法（UPLC-MS/MS）测定不同烘焙条件下7种有机酸的含量。结果表明:7种有机酸化合物在0.5～20.0 mg/kg范围内线性关系良好,决定系数均大于0.990。7种有机酸的加标回收率在81.9%～104.7%,RSD为0.53%～6.64%。洪都拉斯咖啡豆样品检测结果显示随烘焙程度增加,苹果酸和柠檬酸含量下降,富马酸含量先升后降,琥珀酸、酒石酸、莽草酸和奎尼酸含量上升。轻度烘焙下苹果酸与柠檬酸总量最高,达到1201.5 mg/kg,酸度最佳;奎尼酸含量最少,为1363.7 mg/kg,涩度最低。肯尼亚、印尼、巴西、萨尔瓦多咖啡豆中有机酸在相同烘焙条件下表现相似。     

Metabolism of citric and malic acids during ripening of tomato fruit

Tomato fruit at various stages of ripeness were injected with ¹⁴C-labelled citric and malic acids. The ¹⁴CO₂ evolved by individual fruit was determined over a 72 h period and the fruit then analysed for the incorporation of ¹⁴C into sugars, amino acids and individual non-volatile organic acids. In mature green tomato fruit citric and malic acids were found to be metabolised to a comparable extent. Appreciable interconversion occurred together with oxidation to CO₂ and some labelling of glutamic acid and glutamine. In red fruit, citric acid was not as readily oxidised to CO₂ and little conversion to malic acid was observed. On the other hand, malic acid was oxidised to CO₂ and converted to citric acid as rapidly as in green fruit with, in addition, appreciable conversion to glutamic acid. These results are discussed in relation to the changes in concentration of the endogenous acids which take place during the ripening of tomato fruit.     

Changes in the non-volatile organic acids of tomato fruit during ripening

A study has been made of the individual non-volatile organic acids in ethanolic extracts of tomato fruit during ripening. Whole fruit of three varieties and the outer walls and locular contents of one variety each at five stages of ripeness from mature green to full red were analysed. No trace of many of the K rebs-cycle acids could be detected. Maximum citric acid concentrations were found at either the green-yellow or yellow-orange stage of ripeness according to variety. Malic acid concentrations and the malic/citric acid ratio decreased progressively as the fruit ripened. Glutamic acid increased approximately ten-fold and aspartic acid more than doubled from the mature green to red stage of ripeness, but changes in pyrrolidonecarboxylic acid (PCA) during ripening were not statistically significant. In general, similar trends were observed in whole fruit and in the outer walls and locular contents, but malic, citric, glutamic and aspartic acid concentrations were higher in the locular contents than in the outer walls at all stages of ripeness. Alcohol-insoluble solids (AIS) decreased markedly between the green and green-yellow stages and then more slowly with further ripening.     

Preharvest application of methyl jasmonate increases fruit quality and antioxidant capacity in raspberries

The effects of preharvest methyl jasmonate (MJ) application on fruit quality, flavonoid content and antioxidant capacity in black raspberry cv. Jewel (Rubus occidentalis L) and red raspberry cv. Autumn Bliss (Rubus idaeus subsp.) were studied under field condition. Raspberries treated with MJ had higher soluble solids content, total sugars, fructose, glucose, sucrose and lower titratable acids (TAs), malic acid and citric acid than untreated fruit. MJ also significantly enhanced the content of flavonoids and the antioxidant capacities in the fruit. The cv. Jewel had higher soluble solids and lower TAs compared with the cv. Autumn Bliss. On the basis of fresh weight of fruit, ‘Jewel’ also had significantly higher anthocyanin, total phenolic content and antioxidant activity than ‘Autumn Bliss’.