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.     

Damage to intact fruit affects quality of slices from ripened tomatoes

Breaker stage fruit (cvs 901 and Bobcat) were subjected to different types of physical damage: 3 impacts of a steel ball (67 g) from a height of 33, 66 or 99 cm, 8 impacts of the ball from 99 cm, or dropping the fruit once 1 m onto a hard surface. Fruit were then held at 20 °C until full red, sanitized, sliced and stored at 5 °C. Damaged fruit were less firm than undamaged fruit when ripe. Slice quality (appearance, translucency, lycopene content, juice loss) and shelf-life were affected by damage to the fruit. Lycopene concentrations were higher in undamaged (4.0 mg/kg) than damaged fruit (3.5 and 2.7 mg/kg with 3 impacts from 99 cm and drop damage) and decreased during storage at 5 °C. Translucency increased with time and onset was more rapid in moderate to high damage fruit. Juice loss was higher in slices from undamaged (6–8 g/100 g FW) than damaged fruit (1–4 g/100 g). Severe damage resulted in collapse of locular tissue and moderate damage may have induced mealiness. PG activities differed little between slices from severely damaged and undamaged fruit and no differences in PME activities were found.     

Microstructure and bioaccessibility of different carotenoid species as affected by high pressure homogenisation: A case study on differently coloured tomatoes

The effect of high pressure homogenisation (HPH) on structure (Bostwick consistency, particle size distribution and microstructure) and carotenoid in vitro bioaccessibility of different tomato pulps was investigated. HPH decreased tomato particle size due to matrix disruption and increased product consistency, probably due to the formation of a fibre network. Homogenisation also resulted in a decrease of in vitro bioaccessibility of lycopene, ζ-carotene, and lutein. Such decrease was attributed to the structuring effect of HPH. An inverse relation between tomato consistency and carotenoid in vitro bioaccessibility was found. This dependency was affected by carotenoid species and its localisation within the matrix. It could be observed that one matrix (e.g. (homogenised) red tomato pulp) can contain carotenoids with a very low bioaccessibility (lycopene) as well as carotenoids with a very high bioaccessibility (lutein), indicating that carotenoid bioaccessibility is not solely dependent on the matrix.     

不同烤烟基因型非挥发性有机酸和高级脂肪酸含量的变异分析

研究了56个烤烟基因型非挥发性有机酸和高级脂肪酸含量的变异。结果表明:(1)非挥发性有机酸和高级脂肪酸在不同基因型间存在广泛的变异。非挥发性有机酸总量为(27.52±7.23)mg.g-1,其中苹果酸、柠檬酸和乙二酸等3者的含量之和占总量的84.92%。高级脂肪酸总量平均为(10.11±1.24)mg.g-1,其中饱和高级脂肪酸含量为(4.52±0.48)mg.g-1,不饱和高级脂肪酸含量为(5.59±0.79)mg.g-1,二者分别占总量的44.71%和55.29%。(2)聚类分析根据各种有机酸的含量大小分为高、中、低3个类群:非挥发性有机酸含量依次为(35.28±3.23)mg.g-1、(25.96±1.91)mg.g-1和(18.22±2.28)mg.g-1;饱和高级脂肪酸含量依次为(5.35±0.26)mg.g-1、(4.62±0.17)mg.g-1和(4.07±0.19)mg.g-1;不饱和高级脂肪酸含量依次为(7.05±0.57)mg.g-1、(5.78±0.29)mg.g-1和(4.80±0.27)mg.g-1。一般同一种有机酸含量在不同基因型类群之间差异较大,而在类群之内则差异较小。     

A simple ion-exchange chromatographic determination of non-volatile organic acids in some Spanish exotic fruits

High-performance liquid chromatography (HPLC) permits accurate determination of non-volatile acids in fruit. The Spanish exotic fruits assayed were kiwi fruits (Actinidia chinensis), cvs Hayward, Bruno, Monty and Abbot; mangoes (Mangifera indica), cvs Smith and Lippens; papayas (Carica papaya), cv Solo; pineapples (Ananus comosus), cv Smooth Cayenne; and bananas (Musa cavendishii), cv Enana. Sample preparation for HPLC analysis basically consisted of methanol extraction, followed by an easy clean-up with a C18 cartridge. Separation of the different acids was accomplised using an ion-exchange column and detection was monitored at 214 nm. Reproducibility of the minor organic acids was quite acceptable, and the procedure described offers a rapid analytical alternative to gas chromatography. Oxalic, oxoglutaric, citric, galacturonic, tartaric, ascorbic,l-malic, quinic, succinic, fumaric andd-malic acids can be quantified by this method.

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Einfache Bestimmung von nicht-flüchtigen organischen Säuren in verschiedenen spanischen tropischen Früchten durch Ionenaustausch-Chromatographie

Zusammenfassung Die Ionenaustausch-Chromatographie wird als einfache Methode zur Bestimmung von nichtflüchtigen organischen Säuren in tropischen Früchten beschrieben. Die Proben waren Kiwis (Actinidia chinensis), cvs Hayward, Bruno, Monty und Abbot; Mangos (Mangifera indica), cvs Smith and Lippens; Papayas (Carica papaya), cv Solo; Ananas (Ananus comosus), Cv Smooth Cayenne; und Bananen (Musa cavendishii), cv Enana. Als Probenvorbereitung für die HPLC dienten eine Methanolextraktion und eine Reinigung mit C-18-Cartridges. Die verschiedenen Säuren wurden an einer Ionenaustauschsäule getrennt. Die Detektion erfolgte bei 214 nm. Die Methode ermöglicht die Quantifizierung von Ascorbinsäure, Citronensäure, Oxalsäure, Galakturonsäure, Oxoglutarsäure, Chinasäure, Traubensäure, Fumarsäure, Weinsäure,l-Apfelsäure undd-Apfelsäure.

     

非挥发性有机酸与卷烟主流烟气总粒相物pH关系研究

以国内具有代表性的卷烟为研究对象,分别对卷烟样品的非挥发性有机酸含量和卷烟主流烟气粒相物pH进行了测定,通过数学分析研究了非挥发性有机酸含量对烟气粒相物pH的影响.主流烟气粒相物pH值评价指标与有机酸的关联分析结果表明,苹果酸、十五酸、油酸对主流烟气粒相物pH值相对影响较大.对影响主流烟气粒相物pH值的11种非挥发性有机酸的主成分分析结果表明,亚油酸,油酸,苹果酸,棕榈酸,草酸和亚麻酸对主流烟气粒相物pH值相对影响较大.综上可得,苹果酸和油酸对主流烟气粒相物pH值具有较大影响.     

Colour of post-harvest ripened and vine ripened tomatoes (Lycopersicon esculentum Mill.) as related to total antioxidant capacity and chemical composition

Greenhouse grown tomatoes (cvs ‘Durinta’, ‘Favorita’ and ‘Liberto’) were harvested green and vine ripe. Colour measurements and chemical analyses were performed on green, post‐harvest red and vine‐ripe fruits. Partial least square (PLS) regression was applied to predict the ferric reducing ability of plasma (FRAP) by means of colour measurements (L*, a* and b*). The PLS showed that 78% of the variation in colour were able to predict 74% of the variation in FRAP value. Chemical variables and colour variables together were able to predict 88% of the variation in FRAP by means of PLS regression. Linear regression showed a high negative correlation between high values of L*, b* and FRAP, and a high positive correlation between titratable acidity, a*, hue, a*/b*, soluble solids, vitamin C, dry matter and FRAP values. Thus, colour measurements of intact tomatoes can be used as a non‐destructive method to assess total antioxidant capacity of tomatoes.     

基于BSTFA衍生化法白酒不挥发有机酸研究

白酒中不挥发性有机酸可能是白酒呈酸味的重要化合物,为明晰白酒原酒中不挥发性有机酸的组成与含量,采用N,O-双(三甲基硅烷基)三氟乙酰胺(N,O-bis(trimethylsilyl)trifluoroacetamide,BSTFA)衍生化结合气相色谱-质谱(GC-MS)研究白酒中不挥发有机酸,共检测到27种有机酸。通过定量这些有机酸在7种香型白酒原酒中的分布,发现羟基酸的种类最多,且总浓度最高。在检测的所有有机酸中乳酸含量最高,在几百mg/L至几个g/L之间,远远高于其他不挥发有机酸。大多数不挥发有机酸在酱香型、芝麻香型白酒中的含量较高,在清香和凤香白酒中的含量较低。     

Identification and quantitative analysis of sugars and non-volatile organic acids in Chinese gooseberry fruit (Actinidia chinensis Planch.).

The free sugars and non-volatile organic acids in Chinese gooseberry fruit were extracted and separated by lead salt and ion-exchange procedures. Sugars and acids were identified and quantitatively determined by gas-liquid chromatography (g.l.c.) of their trimethylsilyl (TMS) derivatives. Glucose, fructose, sucrose and trace amounts of sorbitol accounted for the total sugars. Citric, quinic and malic are the major acids, the outstanding feature being the high content of quinic acid in mature fruit. Small amounts of phosphoric, ascorbic, glucuronic, galacturonic, oxalic, succinic, fumaric, oxalacetic and p-coumaric acids are also present. Qualitative and quantitative analysis of acids prepared as lead salts agreed closely with the determination of acids isolated by the ion-exchange procedure. Identifications of sugars and acids were confirmed by paper and thin-layer chromatography. Reducing sugars, total sugars and titratable acidity were determined by AOAC methods and the results compared with those from g.l.c.     

谷氨酸发酵过程不同溶氧水平产有机酸

运用HPLC法对标准溶氧水平和低溶氧水平谷氨酸发酵液中的α-酮戊二酸、乳酸、柠檬酸、琥珀酸进行了跟踪检测。结果发现,在不同溶氧水平谷氨酸发酵过程中,四种有机酸的变化趋势比较相似,但其浓度有一定差别。产酸期有机酸分泌到胞外;发酵后期琥珀酸和柠檬酸作为碳源被细胞吸收利用,而乳酸较少被吸收到胞内。低溶氧水平发酵液中乳酸的大量积累,耗糖快、最终糖酸转化率偏低。     

Free amino acids and other non-volatile compounds formed during processing of Iberian ham

Fifty-five legs from Iberian pigs were traditionally processed into dry cured hams. Free amino acids and other non-volatile compounds in the water-soluble fraction from the biceps femoris muscle were analyzed by HPLC. At the drying stage and in the last months in the cellar the largest increases in these water-soluble compounds took place. There was a clear influence on free amino acid formation of salt content and on the formation of peptides of the temperature at each processing stage. As the amount of non-volatile compounds in the water-soluble fraction increases with processing time, their determination could provide a maturation index for Iberian ham.     

Non-volatile organic acids of grasses

Non-volatile organic acids have been determined in S24 ryegrass and S37 cocksfoot harvested on three cutting dates over the period of ear emergence and in eight grasses harvested on two cutting dates. In both S24 ryegrass and S37 cocksfoot the concentrations of shikimic, quinic and total acids decreased with increased age of the plant. Correlation coefficients are given between the concentrations of acids in eight grasses and the ‘preference ranking’ of the grasses estimated in an investigation into the grazing preferences of sheep and cattle, and a regression is given for relating ‘preference ranking’ to the contents of citric and quinic acids.     

有机酸提取技术研究进展

有机酸提取对于研究和利用有机酸具有重要意义。文章综述了近年来有机酸的提取技术,系统介绍了不同技术在有机酸提取方面的原理、特点和应用。     

The identification and quantification of some non-volatile oxidation products of fatty acids developed during prolonged storage of wheat flour

Three white bread flours, stored in good conditions for 5 years have been investigated for the presence of non-volatile oxidation products of linoleic acid. Two products have been identified and their rate of accumulation with time of storage determined.     

Effect of organic growing systems on sensory quality and chemical composition of tomatoes

Tomato plants were grown in the greenhouse in the soil, in confined beds, or in combined beds where the roots could also develop in the soil outside the bed. The beds were filled with compost based on clover grass hay, deep litter and peat and harvested in early summer and autumn in 2002 and 2003, and in the soil treatment the same compost was incorporated into the soil. The tomato fruit quality was assessed by sensory analysis and content of chemical components as, e.g. dry matter, soluble solids, citric acids and volatile components. The content of minerals was mainly determined to evaluate possible limitations in nutrient supply. Due to only minor effects of growing systems on sensory quality and chemical composition of tomato fruits it is concluded that it is possible to produce tomato fruits in confined and combined soil bed systems without any loss in eating quality. Actually the results indicate that a slight increase in quality of tomatoes from the confined and combined systems is obtained. The present result points to the fact that confined and combined growing systems may be new relevant commercial growing systems, in which the quality of tomatoes seems to be ensured, and in which nutrient loss and root diseases contamination can be reduced.     

The growth of salmonellae in tomatoes

The growth of Salmonella enteritidis, S. infantis and S. typhimurium in tomatoes was studied at 7,22 and 30 degrees C. The pH values of tomatoes varied from 3.99 to 4.37 before incubation and from 3.90 to 4.36 after incubation at different temperatures. No growth was observed at 7 degrees C. S. enteritidis, S. infantis and S. typhimurium grew from cell densities of 1.2 x 10(1), 0.7 x 10(1) per g to 2.0 x 10(6), 2.3 x 10(6) and 7.1 x 10(6) per g, respectively, at 22 degrees C in 24 h. At 30 degrees C, the number of bacteria was about one logarithmic unit higher than at 22 degrees C after the same incubation time. The results of this study demonstrated a possible risk of tomatoes as vehicles of Salmonella spp.     

The effects of the organic acids in cocoa on the flavour of chocolate

Samples (54) of dried fermented cocoa beans from different world regions were analysed for levels of organic acids, pH and titratable acidity. The effects of the organic acids on the flavour characteristics of cocoa were examined by sensory evaluation of chocolate made from samples of cocoa beans. Concentrations (g kg^?1) of acids ranged from 1.3 to 11.8 for acetic, 1-6 to 9-9 for citric, 0.6 to 11.1 for lactic and 2.1 to 6.5 for oxalic. pH values ranged from 4.6 to 5.8, while titratable acidity ranged from 0.08 to 0.31 equivalents of sodium hydroxide per kg sample. Cocoas from South East Asia and the South Pacific tended to be more acidic than West African beans in terms of both chemical and sensory characteristics. Lactic and acetic acids were found to be in greater concentrations in cocoas from the former regions and were considered to be largely responsible for higher acid flavour scores. In contrast, citric and oxalic acids were generally lower in these beans. Flavour assessments of cocoas with and without added organic acids indicated that oxalic acid played an important role in chocolate flavour. These results suggest that a reduction in the levels of acetic and lactic acids only, may not be sufficient to produce a desirable flavour balance.     

Cyclodimers of p-coumaric and ferulic acids in the cell walls of tropical grasses

Cell walls from leaves and stems of three tropical grasses (Setaria anceps cv Nandi (Schumach) Moss), pangola grass Digitara decumbens Stent and spear grass Heteropogon contortus (L) Beauv ex Roemer & Schultes were extracted with alkali, and ether-soluble fractions were prepared from the acidified solutions. Cyclobutane dimers derived from p-coumaric acid (CA: 3-(4-hydroxypheny) propenoic acid) and ferulic acid (FA: 3-(4-hydroxy-3-methoxyphenyl) propenoic acid) were found in all plant residues. Structural information on the dimers was obtained by gas chromatography-mass spectrometry. Stem cell walls differed from those of leaf in having major dimer components which contained residues tentatively identified as coniferyl alcohol (3-(4-hydroxy-3-methoxyphenyl)-2-propen-l-ol). Species differences in leaf cell wall cyclodimers were evident. Pangola and setaria grasses had dimers mainly derived from FA, whereas spear grass had over 70% of dimers derived from CA. Di-esterification of some dimers in the cell walls was confirmed by the release of dimers containing the reduced forms of CA and FA (coumaryl and coniferyl alcohols respectively) when leaf cell walls were extracted with borohydride. Head to tail dimerisation giving derivatives of truxillic acid (t-2, c-4-diphenyl-r-l, t-3-cyclobutanedicarboxylic acid) predominated, although evidence was obtained for the presence of head-to-head coumaric acid dimers (derivatives of truxinic acid, t-3, t-4-diphenyl-rl, c-2-cyclobutanedicarboxylic acid) in setaria stem and spear grass leaf. The results suggested that cyclodimers in grass cell walls occurred in cross-linking structures of varying complexity between macromolecules, where they would possibly contribute to fibre strength and thus have an adverse efect on the nutritional value of forage.     

有机酸对黑糯玉米芯色素辅色效果的研究

为改善黑糯玉米芯色素的色泽,提高黑糯玉米芯色素的稳定性,拓宽黑糯玉米芯色素的应用范围,研究了几种不同有机酸对黑糯玉米色素芯辅色作用效果。结果表明,单宁酸、丙二酸和顺丁烯二酸能显著增加黑糯玉米芯色素的吸光度,三者复合使用,辅色效果更显著。通过中心复合设计和多项式回归分析得到3种有机酸对黑糯玉米芯色素吸光度影响的回归方程为:Y=0.810657+0.0422131X1+0.0765179X2+0.151818X3+0.0255187X12-0.00471013X22-0.00471013X32-0.0975X1X2-0.03975X1X3-0.01825X2X3。     

Recovery of n-3 polyunsaturated fatty acids and conjugated linoleic acids in ripened cheese obtained from milk of cows fed different levels of extruded flaxseed

The aim of the study was to investigate whether the addition of extruded flaxseed (EF) in dairy cow diets had an effect on milk fat and individual fatty acids (FA) recovery in cheese after 90 d of ripening. Eighteen Holstein-Friesian cows, divided into 3 experimental groups (6 cows/group), were fed 3 isonitrogenous and isoenergetic diets with 0 (CTR), 500 (EF500), or 1,000 g/d (EF1000) of EF in 3 subsequent periods (2 wk/each), following a 3 × 3 Latin square design. Dry matter intake (DMI) and milk yield were recorded daily. Individual milk samples were collected on d 7 and 13 of each period to determine proximate and FA composition. Eighteen cheese-making sessions (2 for each group and period) were carried out, using a representative pooled milk sample obtained from the 6 cows of each group (10 L). At 90 d of ripening, cheeses were analyzed for proximate and FA composition. Cheese yield was computed as the ratio between the weights of ripened cheese and processed milk. Recoveries of fat, individual FA, and grouped FA were computed as the ratio between the corresponding weights in cheese and in milk. Inclusion of EF did not affect DMI, milk yield, or milk composition. Compared with CTR, the 2 diets containing EF increased the proportion of C18:3n-3 and total n-3 FA, in both milk and cheese. Cheese yield and cheese fat percentage did not differ among diets. Likewise, milk fat recovery in cheese was comparable in the 3 treatments and averaged 0.85. The recoveries of individual FA were, for the most part, not dissimilar from fat recovery, except for short-chain saturated FA (from 0.38 for C4:0 to 0.80 for C13:0), some long-chain saturated FA (0.56 and 0.62 for C20:0 and C21:0, respectively), and for C18:3n-6 (1.65). The recovery of saturated FA was lower than that of monounsaturated FA, whereas recovery of polyunsaturated FA was intermediate. Compared with medium- and long-chain FA, short-chain FA were recovered to a smaller extent in cheese. No differences in recovery were found between n-6 and n-3 FA. In conclusion, FA have different recoveries during cheese-making, with lower values for the short-chain compared with long-chain FA, and for saturated FA compared with unsaturated FA. The addition of EF in dairy cow diets did not influence cheese yield or fat recovery in cheese, irrespective of the inclusion level. The experiment confirmed that feeding cows with EF represents a successful strategy for improving the FA profile of dairy products, through an increase of n-3 FA.