HPLC Analysis of Organic Acids and Sugars in Tomato Juice

1-Ethyl-3-methylimidazolium acetate pretreatment for maximizing reducing sugar recovery from mixed cabbage residue

Vegetable waste, including mixed cabbage residue (MCR), is considered a promising raw material for bioenergy production because of its high lignocellulosic component. In this study, the pretreatment of MCR by ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) was optimized based on response surface methodology. The optimal condition for MCR pretreatment was determined at 55.8 °C, with a reaction of 2.65 h and liquid-solid ratio of 4.60:1 v/w. Hydrolysis of pretreated MCR from optimal pretreatment conditions generated a maximum glucose yield of 156.65 ± 7.66 mg/g MCR. Untreated and pretreated MCRs were successfully characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The pretreated MCR exhibited increased clear pores and incomplete structure. Moreover, compared with untreated biomass, decreased lignin, decreased hemicellulose, increased surface area, and cellulose crystallinity were observed. Thus, [Emim][OAc] pretreatment is a promising alternative approach for higher glucose production from MCR.

Dynamic Change of Carbon and Nitrogen Sources in Colonized Apples by Penicillium expansum

Penicillium expansum is a necrotrophic pathogen, which actively kills host cells and obtains nutrients from dead cells to achieve infection. However, few reports have elucidated the differential levels of carbon and nitrogen sources over increasing distances of the leading edge in fungal colonized fruit tissues during colonization. Our results showed that the highest consumption of sucrose and fructose, as well as the accumulation of glucose, were found in the decayed region of P. expansum-colonized ‘Delicious’ apple fruit compared with the healthy region at the leading edge and the healthy region 6 mm away from the leading edge. As nitrogen sources, the contents of methionine, glutamate, leucine, valine, isoleucine and serine were the lowest in the decayed region compared with the healthy regions during colonization. In addition, the titratable acidity, oxalic acid, citric acid, succinic acid and malic acid showed the highest accumulation in the decayed region compared with the healthy regions. P. expansum colonization induced the accumulation of saturated fatty acids in the decayed region, while the level of unsaturated fatty acids was the lowest. These changes were not observed in the healthy regions. These results indicated that P. expansum kills cells in advance of its colonization in order to obtain the nutrients of the apple tissue from the distal leading tissue of the colonized apple. It is understood that more carbon and nitrogen sources are required for fungal colonization, and a stronger defense response against colonization occurred in the fruit, causing the transit of nutrients from the distal tissue to the infected sites.

Comparison of Quality Characteristics of Tomato Paste Produced under Atmospheric Conditions and Vacuum Evaporations

Herein we report a comparison study of the quality characteristics of tomato paste produced under atmospheric conditions and vacuum evaporation. Tomato pulp (5 Brix) was evaporated under vacuum and at atmospheric pressure using a developed evaporation equipment for household application. Various quality i.e. a* and a*/b* color values, soluble solids content, dark speck amount, titratable acidity, lycopene content and sensory properties of tomato paste were compared. The final total soluble solid contents were not affected by evaporation method whereas the lycopene content in vacuum evaporated samples was found as higher than that in the atmospheric ones at the same soluble solid content. Overall preference scores of vacuum evaporated tomato paste have approximately equal scores with the paste produced at atmospheric conditions.

Quantification of sugars and organic acids in tomato fruits

Sugar and organic acid contents are major factors for tomato fruit flavour and are important breeding traits. Here we provide an improved protocol for accurate quantification of the main sugars, glucose and fructose, and the organic acids, citric acid and malic acid, present in tomato. The tomato extract is spiked with lactose and tricarballylic acid as internal standards and loaded onto a NH2 solid phase extraction (SPE) column. The sugars appear in the flow-through and are subsequently analysed by HPLC using a Nucleodur NH2 column and a refractive index detector. The organic acids bind to the SPE column and are eluted with 400 mM phosphoric acid. For analysis, the organic acids are separated by HPLC using a Nucleodur C18ec column and detected by UV absorption at 210 nm. The method shows excellent inter-day and intra-day reproducibility for glucose, fructose and citric acid with standard deviations of 1–5%. Quantification of citric acid by HPLC and GC–MS showed perfect agreement with a deviation of less than 3%.

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Simple method for quantification of glucose, fructose, citric acid and malic acid in tomato.

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Efficient removal of interfering compounds by solid phase extraction.

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High intra and inter-day reproducibility.

Chemical and functional characterization of seed, pulp and skin powder from chilto (Solanum betaceum), an Argentine native fruit. Phenolic fractions affect key enzymes involved in metabolic syndrome and oxidative stress

The aim of this work was to assess the nutritional and functional components of powder obtained by lyophilization of whole fruits, seeds, pulp and skin from chilto (Solanum betaceum Cav) cultivated in the ecoregion of Yungas, Argentina. The powders have low carbohydrate and sodium content and are a source of vitamin C, carotenoid, phenolics, potassium and fiber. The HPLC-ESI-MS/MS analysis of the fractions enriched in phenolics allowed the identification of 12 caffeic acid derivatives and related phenolics, 10 rosmarinic acid derivatives and 7 flavonoids. The polyphenols enriched extracts before and after simulated gastroduodenal digestion inhibited enzymes associated with metabolic syndrome, including α-glucosidase, amylase and lipase and exhibited antioxidant activity by different mechanisms. None of the analyzed fruit powders showed acute toxicity or genotoxicity. The powders from the three parts of S. betaceum fruit may be a potential functional food and the polyphenol enriched extract of seed and skin may have nutraceutical properties.

Changes in pH, acids, sugars and other quality parameters during extended vine holding of ripe processing tomatoes

BACKGROUND

Two important quality attributes of processing tomatoes are pH and titratable acidity. These and other quality attributes can be affected by tomato fruit maturity and over-maturity. We have determined the magnitude of these maturity effects in four processing tomato cultivars commonly grown in California.

RESULTS

Allowing tomatoes to remain on the vine for up to 4 weeks after ripening resulted in an increase in fruit pH of between 0.01 and 0.02 unit per day for the four cultivars examined. The increase in pH was paralleled by a decrease in titratable acidity, due to a loss of citric acid. Glucose and fructose concentrations also declined with increasing maturity after ripening. Other quality parameters (color, lycopene, total pectin, pectin solubility, and Bostwick consistency) all showed little change.

CONCLUSION

Vine holding of ripe fruit adversely affects quality, especially pH and titratable acidity. Recent problems with high tomato juice pH encountered by tomato processors in California could be the result of increased average fruit maturity at harvest.

Effects of rhizodeposition of non-transgenic and transplastomic tobaccos on the soil bacterial community

The effect of root-released compounds of transplastomic tobacco (Nicotiana tabacum) on the soil bacterial community structure, and their potential to support horizontal gene transfer (HGT) to bacteria have been studied. Soil microcosms were exposed to root-released compounds collected from transplastomic and non-transgenic tobacco cultivars. Cluster analysis of automated ribosomal intergenic spacer analysis (ARISA) profiles of the soil bacterial community after 48 h incubation grouped the transgenic cultivar apart from the non-transgenic, indicating that it had a rhizodeposition pattern different from the parental plants. However, these differences were less than between the two non-transgenic tobacco cultivars studied. NMR characterization of the root-released compounds showed some differences in chemical fingerprinting pattern between the transplastomic and the parental cultivar. However, the effect on bacterial community structure was transient, and tended to disappear after 96 h of incubation. The potential of root-released compounds as a source of transforming DNA for bacteria was investigated by using four potential recipient species. No transformants were obtained following exposure of all the recipients to the root-released compounds. Root-released compounds amended to transgene donor DNA decreased the transformation frequency of Acinetobacter baylyi strain ADP1200, while Azospirillum, Agrobacterium, and Sinorhizobium strains failed to develop competence also in the presence of an external added transgene source. Detection of plastid sequences by PCR suggested that a very low amount of fragmented plastid donor DNA was present in the root-released compounds.

Rapid determination of minority organic acids in honey by high-performance liquid chromatography

A rapid high-performance liquid chromatographic method for the determination of organic acids in honey is reported. Malic, maleic, citric, succinic and fumaric acids were identified and quantified in 15 min. First time repeatibility, reproducibility and recoveries were determined out for these acids in honey samples. Maleic acid was also quantified for first time by a chromatographic method. The organic acids were removed from honey by using a solid-phase extraction procedure with anion-exchange cartridges. Previously, the solution of honey was adjusted to pH 10.50 with 0.1 M NaOH and stirred for 15 min at room temperature. Then, this solution was adjusted to pH 5.00 with 0.1 M H2SO4. This procedure was carried out to avoid interferences in the baseline. The chromatographic separation was achieved with only one Spherisorb ODS-2 S5 column thermostated at 25 degrees C. Metaphosphoric acid (pH 2.20) was used as mobile phase at a flow-rate of 0.7 ml/min. Organic acids were detected with a UV-vis detector (215 nm). The precision results showed that the relative standard deviations of the repeatability and reproducibility were < or =3.20% and < or =4.86%, respectively. The recoveries of the organic acids ranged from 62.9 to 99.4%. Under optimum conditions the detection limits ranged from 0.0064 to 7.57 mg/kg and the quantification limits ranged from 0.025 to 10.93 mg/kg.

Solid-phase extraction procedure to remove organic acids from honey

A solid-phase extraction procedure was applied to remove organic acids from honey. Malic, maleic, citric, succinic and fumaric acids were isolated with an anion-exchange cartridge. The different parameters which affected the extraction procedure were studied and optimised to establish the optimal conditions for maximum recovery of organic acids and minimum extraction of interferences. The optimised procedure used a cartridge which was activated with 10 ml of 0.1 M sodium hydroxide solution (percolation rate 3 ml/min). A 10 ml volume of honey solution was passed at a flow-rate of 0.5 ml/min. The cartridge was washed with 10 ml of water (3 ml/min) and organic acids were eluted with 4 ml of 0.1 M sulfuric acid (0.5 ml/min). This solution was injected directly into the chromatograph. When this procedure was carried out on standard solutions of organic acids, recoveries between 99.2 and 103.4% were found. If this procedure was applied to honey samples these recoveries were also satisfactory and ranged from 62.9 to 99.4%.

Routine high-performance liquid chromatographic determination of carboxylic acids in wines and champagne

Carboxylic acids have an important influence on the biological stability and the organoleptic properties of wines. A simple, rapid and reproducible high-performance liquid chromatographic method for the determination of the main carboxylic acids (tartaric, malic, shikimic, lactic, acetic, citric, succinic, fumaric and propionic acids) in wines is described. There is no interference from either sugars or amino acids. The method does not need any preparation or extraction of the sample. The linearity, the level of detection, the repeatability and the reproducibility were studied for each acid. The results are compared with those obtained by chemical and enzymatic assays.