Non-volatile Organic Acids Research Articles

Chemometric profiling of pre-climacteric Sri Lankan mango fruit ( Mangifera indica L.)

There is no published information on the genotypic variation of major biochemical constituents in mango fruit endemic to Sri Lanka. Accordingly, non-structural carbohydrates, non-volatile organic acids and total phenolics were determined from the peel and pulp of pre-climacteric Sri Lankan mango cultivars ( viz. Willard, Karutha Colomban, Vellai Colomban, Ampalavi, and Malgova) at three different maturity stages. Principal components analysis revealed distinct clustering of samples according to their biochemical profiles of peel and pulp at three maturity stages. Sugar concentrations generally declined with maturity in both peel and pulp except for cv. Willard. Fructose was the predominant sugar in both peel (56.2–106 mg/g dry weight (DW)) and pulp (67.4–141 mg/g DW), followed by glucose and sucrose. Starch concentration increased with maturity and was higher in pulp (26.0–55.0% DW) than peel (18.2–38.9% DW) at full mature stage. Dry matter as a proportion of fresh weight (FW) increased with maturity.

Simultaneous determination of non‐volatile, semi‐volatile, and volatile organic acids in tobacco by SIM–Scan mode GC–MS

A method for simultaneous determination of seven nonvolatile organic acids (NVOAs), five semivolatile organic acids (SVOAs), and twelve volatile organic acids (VOAs) in tobacco by synchronous SIM (Selected Ion Monitoring)-scan mode GC-MS was developed. The collection of NVOAs and SVOAs data was performed in full-scan mode, and that of VOAs data was carried out with SIM. Recoveries of NVOAs and SVOAs varied from 90.0 to 103.0%, and RSDs were less than 4.0%; recoveries of VOAs ranged from 89.5 to 99.3%, and their RSDs were less than 3.0%. Twelve tobacco samples were analyzed by the described method, and the results show that the method is applicable for the simultaneous determination of VOAs, NVOAs, and SVOAs in tobacco.

The gas-phase ozonolysis of unsaturated volatile organic compounds in the troposphere

The gas-phase reactions of ozone with unsaturated hydrocarbons are significant sources of free radical species (including *OH) and particulate material in the Earth's atmosphere. In this tutorial review, the kinetics, products and mechanisms of these reactions are examined, starting with a discussion of the original mechanism proposed by Criegee and following with a summary presentation of the complex, free radical-mediated reactions of carbonyl oxide (Criegee) intermediates. The contribution of ozone-terpene reactions to the atmospheric burden of secondary organic aerosol material is also discussed from the viewpoint of the formation of non-volatile organic acid products from the complex chemistry of ozone with alpha-pinene. Throughout the article, currently accepted understanding is supported through the presentation of key experimental results, and areas of persistent or new uncertainty are highlighted.

천연 게 향료 제조를 위한 농축 붉은 대게 가공 자숙액의 특성

This study was red snow crab Chionoecetes japonicus cooker effluent (RSCCE) for making a natural crab-like flavorant. The RSCCE (<TEX>$1\;^{\circ}Brix$</TEX> in the initial state) was concentrated up to <TEX>$40^{\circ}Brix$</TEX> to determine the optimal conditions for making a natural flavorant. During concentration, the amino-N content and total acidity increased with the concentration time, while the pH was maintained in range 7.94-8.78. In the acceptance test and quantitative description analysis (QDA), <TEX>$20^{\circ}Brix$</TEX> RSCCE had the best quality in terms of taste (5.87), odor (6.00), and overall acceptance (5.80). Of the taste compounds analyzed in <TEX>$20^{\circ}Brix$</TEX> RSCCE, lactic acid was an abundant non-volatile organic acid, and the nucleotide 5'-inosine monophosphate (IMP) was present, as were four free amino acids: tyrosine, glutamic acid, alanine and glycine. The taste and odor of boiled crabmeat were retained in <TEX>$20^{\circ}Brix$</TEX> RSCCE based on the QDA.

Upgrading Bio-oil over Different Solid Catalysts

Solid acid 40SiO2/TiO2−SO42- and solid base 30K2CO3/Al2O3−NaOH were prepared and compared with catalytic esterification activity according to the model reaction. Upgrading bio-oil by solid acid and solid base catalysts in the conditioned experiment was investigated, in which dynamic viscosities of bio-oil was lowered markedly, although 8 months of aging did not show much viscosity to improve its fluidity and enhance its stability positively. Even the dehydration by 3A molecular sieve still kept the fluidity well. The density of upgraded bio-oil was reduced from 1.24 to 0.96 kg/m3, and the gross calorific value increased by 50.7 and 51.8%, respectively. The acidity of upgraded bio-oil was alleviated by the solid base catalyst but intensified by the solid acid catalyst for its strong acidification. The results of gas chromatography−mass spectrometry analysis showed that the ester reaction in the bio-oil was promoted by both solid acid and solid base catalysts and that the solid acid catalyst converted volatile and nonvolatile organic acids into esters and raised their amount by 20-fold. Besides the catalytic esterification, the solid acid catalyst carried out the carbonyl addition of alcohol to acetals. Some components of bio-oil undertook the isomerization over the solid base catalyst.

Microbial populations and activities in the rhizoplane of rock-weathering desert plants. I. Root colonization and weathering of igneous rocks.

Dense layers of bacteria and fungi in the rhizoplane of three species of cactus (Pachycereus pringlei, Stenocereus thurberi, Opuntia cholla) and a wild fig tree (Ficus palmeri) growing in rocks devoid of soil were revealed by bright-field and fluorescence microscopy and field emission scanning electron microscopy. These desert plants are responsible for rock weathering in an ancient lava flow at La Purisima-San Isidro and in sedimentary rock in the Sierra de La Paz, both in Baja California Sur, Mexico. The dominant bacterial groups colonizing the rhizoplane were fluorescent pseudomonads and bacilli. Seven of these bacterial species were identified by the 16S rRNA molecular method. Unidentified fungal and actimomycete species were also present. Some of the root-colonizing microorganisms fixed in vitro N(2), produced volatile and non-volatile organic acids that subsequently reduced the pH of the rock medium in which the bacteria grew, and significantly dissolved insoluble phosphates, extrusive igneous rock, marble, and limestone. The bacteria were able to release significant amounts of useful minerals, such as P, K, Mg, Mn, Fe, Cu, and Zn from the rocks and were thermo-tolerant, halo-tolerant, and drought-tolerant. The microbial community survived in the rhizoplane of cacti during the annual 10-month dry season. This study indicates that rhizoplane bacteria on cacti roots in rock may be involved in chemical weathering in hot, subtropical deserts.

저온저장한 수삼의 가공 중 성분변화

10월 초에 채굴한 6년근 수삼을 4<TEX>$^{\circ}C$</TEX><TEX>$\pm$</TEX>1<TEX>$^{\circ}C$</TEX>, RH 87∼92%에 10주간 저장하면서 1주 간격으로 시료 채취하여 동결건조 인삼과 홍삼을 제조하여 성분변화를 비교조사 하였다. 총당은 저장기간의 경과에 따라 홍삼은 약간 감소하였고, 환원당은 증가하여 저장전 1.48%에서 10주째는 23.33%였다. 유리당은 홍삼에서 fructose는 증가하였으나 glucose와 sucrose 는 증가후 감소하였고 maltose는 6.62%에서 점차 감소하였으며, 동결건조인삼은 fructose, glucose, sucrose 모두 증가하여 특히 sucrose는 저장전 10.96%에서 7주째는 24.38%로 증가하였고 maltose는 검출되지 않았다. 물추출물의 수율은 7 <TEX>$.$</TEX> 8주째가 약간 높았고, pH는 3 <TEX>$.$</TEX> 4주째가 약간 높았으며. 탁도는 동결건조인삼은 변화가 없으나 홍삼은 감소하였다. 비수용성 단백질은 홍삼에서 검출되지 않았으며 동결건조인삼은 저장기간의 경과에 따라 비수용성단백질은 감소하고 수용성단백질은 증가하는 경향을 보였다. 페놀화합물은 홍삼과 동결건조인삼에서 각각 저장 7주와 9째 가장 높았으나 그 양은 홍삼이 높았다. 비휘발성유기산은 동결건조인삼과 홍삼 모두 citric acid는 감소하였고, glutamic acid와 pyruvic acid는 동결건조인삼에서 미량이었으나 홍삼은 최고 37 <TEX>$\mu$</TEX>g/g과 592 <TEX>$\mu$</TEX>g/g이 검출되었다. The six-year old fresh ginseng collected at earlier October was stored for 10 weeks in the condition of 4<TEX>$^{\circ}C$</TEX><TEX>${\pm}$</TEX>1<TEX>$^{\circ}C$</TEX> and RH 87∼92%, and the chemical components were investigated in an interval oi one week by taking sample of it after making it to the freeze-dryed ginseng and the red ginseng. The total sugar content of the red ginseng was a little reduced as the period of storage elapsed, and the reducing sugar content was 1.48eic before it was stored and was increased to 23.33% after 10 weeks of storage. For the free sugar of the red ginseng, the content of the fructose was increased, bit the contents of the glucose and the sucrose were gradually decreased after it was a little increased. The content of the maltese was 6.62% before storage and it was gradually decreased. For the free sugar of the freeze-dryed ginseng, the contents of the fructose, the glucose and the sucrose were increased. Especially the content of the sucrose was 10.96% before it was stored and was a increased to 24.38% after 7 weeks of storage, and the content of maltose was not detected. The yield of water extract was a little high at 7-8 weeks of storage and the pH was a little high at 3-4 weeks of storage. The turbidity was not changed for the freeze-dryed ginseng but was decreased for the red ginseng The water non-soluble protein was not detected in the red ginseng, and for the freeze-dryed ginseng the water non-soluble protein was reduced and the water soluble protein was increased as the period of storage was elapsed. The contents of the phenolic compounds for the red ginseng and the freeze-dryed ginseng and have their peak values after 7 and 9 weeks of storage respectively, and the amount of phenolic compounds was larger for the red ginseng. For the content of the non-volatile organic acids, the content of the citric acid was decreased both for the red ginseng and the freeze-dryed ginseng, and the contents of the glut-matic acid and the pyruvic acid were very small for the freeze-dryed ginseng, but were detected in the red ginseng at a maximum value of 37 <TEX>${\mu}$</TEX>g/g and 592 <TEX>${\mu}$</TEX>g/g respectively.

Chemical Characteristics of Commercial Korean Soy Sauce Produced by Alkali Treatment Following Acidic Hydrolysis

Alkali treatment following acidic hydrolysis (ATAH) is a commonly used practice for reducing the levels of monochloropropanediol in commercial Korean soy sauce. This study investigated the chemical compounds produced in commercial Korean soy sauce made by ATAH. The levels of amino-N, total acidity, pH, salinity and Brix of the soy sauce were 6.66%, 2.52%, 19.81%, 4.57 and 35.01, respectively. The major fatty acids were C18:2n-6, C16:0, C18:1n-9 and C18:3n-6. The concentration of polyunsaturated fatty acids were especially high, with of C18:2n-6 (49.8%) being the highest followed by C18:3n-6 (3.8%) and C18:3n-3 (2.4%) in that order. Among the non-volatile organic acids, the concentration of levulinic acid (1,206.28 mg/100 g) was the highest, while the taste value of citric acid was the highest. Among the ATP related compounds, IMP concentration (31.19 mg/100 g) was highest followed by AMP, hypoxanthine and GMP in that order. The concentrations of free and total amino acids in soy sauce were 6,136.94 mg/100 g and 8,702.76 mg/100 g, respectively. On the other hand, the taste value of glutamic acid, a major amino acid flavor determinant in soy sauce, was highest of all the amino acids, which is desirable since most free amino acids such as methionine, histidine and phenylalanine have a bitter taste that detracts from the flavor of soy sauce.

Crescimento radicular e produção de ácidos orgânicos em cultivares de soja com diferentes tolerâncias ao alumínio

A elucidação dos mecanismos que definem o comportamento diferencial entre genótipos de soja quanto à toxidez de Al facilita a utilização da variabilidade genética existente ou produzida. O objetivo deste trabalho foi avaliar a influência do Al no crescimento radicular, na modificação do pH da solução e no conteúdo de ácidos orgânicos em extratos de raízes de cultivares de soja tolerantes ao Al, FT-1 e FT-6 (Veneza) e sensíveis, IAC-13 e Paraná. As plantas cresceram por nove dias em solução contendo 50 mg L-1 de Ca e 0,0 e 0,2 mg L-1 de Al, com pH inicial de 4,76. Houve maior crescimento de raízes nas cultivares tolerantes e não houve alterações do pH da solução relacionadas à tolerância das cultivares ao alumínio. A presença do Al reduziu o conteúdo dos ácidos cítrico, lático, succínico, oxálico e málico, em ambos os grupos de cultivares avaliados, porém com maior redução no grupo das cultivares sensíveis. O ácido cítrico foi encontrado em maior quantidade nas cultivares tolerantes. A capacidade das cultivares de soja FT-1 e FT-6 (Veneza) de alterar o conteúdo de ácidos orgânicos não-voláteis, principalmente o ácido cítrico, que pode complexar o Al, indica que este mecanismo pode ser muito importante para a tolerância a esse elemento.

Characterization of cigar tobaccos by gas chromatographic/mass spectrometric analysis of nonvolatile organic acids: application to the authentication of Cuban cigars.

A reliable method based on gas chromatographic/mass spectrometric (GC/MS) profiling of nonvolatile organic acids is described for the characterization of cigars. The method involves an aqueous extraction of ground tobacco and selective isolation of the acids by simply stirring strong anion exchange (SAX) disks in the aqueous tobacco extract. The acids are then directly silylated on the disk with N-methyl-N-trimethylsilyl-trifluroacetamide (MSTFA) in acetonitrile in an autosampler vial. Elution of the derivatized acids in situ allows the sample to be directly analyzed by GC/MS without further sample handling. Compared to the conventional disk-extraction technique using a vacuum manifold, this method is much less labor intensive, and is desirable for multiple sample analysis. Nicotinic acid, succinic acid, glyceric acid, malic acid, pyroglutamic acid, threonic acid, citric acid, uracil, and an unidentified acid were reproducibly quantified in tobacco samples. Principal component analysis (PCA) of the acid profiles of the filler tobaccos of 18 Cuban cigars and 31 non-Cuban cigars shows separation of the two groups, indicating that the acid profiles are potentially useful in the authentication of Cuban cigars.

Contributions of Nonvolatile Phytochemicals to Nutrition and Flavor

Small fruit are rich in several types of phytochemicals, vitamins, and minerals. These compounds have health functional properties that may protect humans from cardiovascular disease and certain cancers. Several of these phytochemicals, such as dietary fiber, anthocyanins, and polyphenolics, also contribute to small fruit quality. Other components contribute to appearance and taste. Nonvolatile organic acids contribute to the perceived sourness of small fruit and changes in levels can alter visual color by affecting cellular pH and anthocyanin structure. The soluble sugars glucose, fructose, and sucrose contribute directly to the perceived sweetness of the fruit and provide carbohydrates for other metabolic functions such as phenolic and ascorbic acid synthesis.

Analysis of gas‐aerosol partitioning in the Arctic: Comparison of size‐resolved equilibrium model results with field data

Size‐resolved aerosol mass and gas concentrations were measured during the European Arctic Aerosol Study (EAAS). A thermodynamic equilibrium model was applied to the data in order to (1) test whether gas‐aerosol equilibrium appeared to be obtained by NH3, HNO3, HCl, HCOOH, and CH3COOH, and (2) test the sensitivity of gas‐aerosol equilibrium to several nonvolatile organic acids that were measured. Model results indicated that all submicrometer, accumulation‐mode aerosols appeared to be near equilibrium with NH3. Supermicrometer, coarsemode aerosols of recent marine origin appeared to be out of equilibrium with HNO3 and closer to equilibrium with HCl, while continentally influenced aerosols sometimes appeared to be near equilibrium with both HNO3 and HCl. However, the observed gas‐aerosol partitioning of HCOOH and CH3COOH could not be explained by effective Henry's law partitioning, consistent with other studies. Nonvolatile organic acids measured were methanesulfonate, oxalate, succinate, and glutarate. Sensitivity tests indicated that methanesulfonate retained ∼30% of NH4+ under marine conditions but had &lt;3% impact on other species and under other conditions. Whereas oxalic acid was predicted to be ∼15–30% dissociated in the aerosol solution, succinic and glutaric acids were predicted to be &lt;10% dissociated, limiting their ability to influence gas‐aerosol partitioning. Together, the three dicarboxylic acids were responsible for retaining 0–2% of predicted NH4+ and displacing 0–6% of predicted Cl− and NO3−. Model results were sensitive to the assumed mixing state of the aerosols, as well as the degree of aerosol size resolution represented by the model.

Phosphate-solubilizing microorganisms associated with the rhizosphere of mangroves in a semiarid coastal lagoon

The phosphate-solubilizing potential of the rhizosphere microbial community in mangroves was de- monstrated when culture media supplemented with in- soluble, tribasic calcium phosphate, and incubated with roots of black (Avicennia germinans L.) and white (La- guncularia racemosa (L.) Gaertn.) mangrove became transparent after a few days of incubation. Thirteen phosphate-solubilizing bacterial strains were isolated from the rhizosphere of both species of mangroves: Ba- cillus amyloliquefaciens, Bacillus licheniformis, Bacillus atrophaeus, Paenibacillus macerans, Vibrio proteolyti- cus, Xanthobacter agilis, Enterobacter aerogenes, Ente- robacter taylorae, Enterobacter asburiae, Kluyvera cryo- crescens, Pseudomonas stutzeri, and Chryseomonas lu- teola. One bacterial isolate could not be identified. The rhizosphere of black mangroves also yielded the fungus Aspergillus niger. The phosphate-solubilizing activity of the isolates was first qualitatively evaluated by the for- mation of halos (clear zones) around the colonies grow- ing on solid medium containing tribasic calcium phos- phate as a sole phosphorus source. Spectrophotometric quantification of phosphate solubilization showed that all bacterial species and A. niger solubilized insoluble phosphate well in a liquid medium, and that V. proteo- lyticus was the most active solubilizing species among the bacteria. Gas chromatographic analyses of cell-free spent culture medium from the various bacteria de- monstrated the presence of 11 identified, and several unidentified, volatile and nonvolatile organic acids. Those most commonly produced by different species were lactic, succinic, isovaleric, isobutyric, and acetic acids. Most of the bacterial species produced more than one organic acid whereas A. niger produced only suc- cinic acid. We propose the production of organic acids by these mangrove rhizosphere microorganisms as a possible mechanism involved in the solubilization of in- soluble calcium phosphate.

Differentiation of raspberry varieties according to anthocyanin composition

Four Spanish raspberry (Rubus idaeus L.) cultivars, Autumn Bliss, Heritage, Rubi, and Ceva, were studied in order to determine, qualitatively and quantitatively, both anthocyanins and vitamin C composition, owing to their significance as dietary compounds with antioxidant activity and also to the relation with color quality. Raspberry anthocyanin composition, determined by HPLC and GC-MS, was characteristic to each cultivar. The higher anthocyanin content expressed as cyanidin-3-glucoside was found in the late cultivars, Rubi (96.08 mg/100 g f.w.) and Ceva (122.88 mg/100 g f.w.). Three cultivars showed cyanidin-3-sophoroside (63.86–21.91 mg/100 g f.w.) and cyanidin-3-glucoside (25.12–14.00 mg/100 g f.w.) as the major pigments, while Autumn Bliss had a similar relative amount of cyanidin derivatives, cyanidin-3-rutinoside being the pigment in major concentration (10.53 mg/100 g f.w.). The vitamin C contents were determined by HPLC. The Rubi cultivar showed the highest amount of vitamin C (31.14 mg/100 g f.w.). The organic acids were determined by HPLC as fruit constituents related to color quality. Citric acid was the main non-volatile organic acid (90%) in all raspberry cultivars and the Rubi cultivar showed the highest total non-volatile organic acids content (2003 mg/100 g f.w.). Hunter color CIE values were also determined, showing that Rubi was the reddest raspberry cultivar.

Biodegradation of crude oil into nonvolatile organic acids in a contaminated aquifer near Bemidji, Minnesota

As the result of a pipeline burst, a body of light aliphatic crude oil floats atop the groundwater in a shallow sand and gravel aquifer in a remote area outside Bemidji, Minnesota. Biodegradation has resulted in the formation of a plume of DOC downgradient from the oil body. Groundwater has also been contaminated in an area known as the spray zone, from vertical infiltration of DOC resulting from biodegradation of crude oil in the overlying unsaturated zone. The majority of DOC in the contaminated groundwater is in the form of nonvolatile organic acids (NVOA's) which represent the partial oxidation products of the crude oil constituents. The NVOA's have been classified into three fractions according to their isolation on XAD resins: hydrophobic neutrals (HPO-N), hydrophobic acids (HPO-A) and hydrophilic acids (HPI-A). These fractions of NVOA's were isolated from a well downgradient from the oil body (well 530; DOC=21 mg C/l), from a well in the spray zone (well 603; DOC=15 mg C/l) and from an uncontaminated well upgradient of the oil body where the naturally occurring DOC is 2.9 mg C/l (well 310). The three sets of NVOA's were characterized by elemental analyses, molecular weight determinations, 14C ages and liquid phase 1H and 13C NMR. The crude oil and the saturate, aromatic, resin and asphaltene fractions of the crude oil were similarly analyzed by elemental analysis and NMR. The NVOA's from the contaminated wells were clearly distinguishable from the naturally occurring groundwater DOC. Based upon molecular weights, sulfur contents, aromaticities and the presence of methyl groups bonded to aromatic rings, the characterization data suggests that the NVOA's originate from the C 18 or greater alkylaromatic, naphthenoaromatic and sulfur-containing constituents of the crude oil, including possibly the resins and asphaltenes.

Uptake and Transformation of Benzene and Toluene by Plant Leaves

The [1-6 14C]benzene and [1- 14C]toluene vapors penetrate into hypostomatous leaves of Acer campestre, Malus domestica,and Vitis viniferafrom both sides, whereas hydrocarbons are more intensively absorbed by the stomatiferous side and more actively taken up by young leaves. Benzene and toluene conversion in leaves occurs with the aromatic ring cleavage and their carbon atoms are mainly incorporated into nonvolatile organic acids, while their incorporation into amino acids is less intensive. Intact spinach chloroplasts oxidize benzene, and this process is strongly stimulated in light. Oxidation of benzene by spinach chloroplasts or by enzyme preparation from spinach leaves is almost completely inhibited by 8-oxyquinoline or sodium diethyldithiocarbamate, and slightly affected by α,α′-dipyridyl. Benzene oxidation by enzyme preparation is significantly stimulated by NADH and NADPH; in their presence, the benzene hydroxylation product, phenol, is formed in a determinable amount. It is supposed that the enzyme performing the first step of oxidative transformation of benzene in plant leaves contains copper as the prosthetic group.

Taste and flavor compounds in box thorn ( Lycium chinense Miller) leaves

Contents of selected taste components in box thorn leaves collected at different seasons (from mid-May to mid-October) were determined. Volatile flavor compounds in the box thorn leaves were extracted using a simultaneous steam distillation-extraction apparatus, and the compounds were isolated and identified by gas chromatography/mass spectrometry. Box thorn leaves contained fructose (0.58–1.54%), glucose (0.33–1.33%), sucrose (0.23–0.68%) and maltose (0.60–0.98%). Non-volatile organic acids identified were citric acid (162.3–361.3 mg%), oxalic acid (61.1–130.9 mg%), malonic acid (44.9–59.4 mg%), malic acid (15.6–34.3 mg%), succinic acid (3.7–5.1 mg%), fumaric acid (1.3–2.9 mg%), and lactic acid (0.0–1.1 mg%). Eighteen free amino acids were found in the leaves and their contents varied greatly with season. Proline (52.6–267 mg%), histidine (162–244 mg%) alanine (99.5–198 mg%), leucine (51.4–149 mg%), valine (54.5–125 mg%), isoleucine (37.0–119 mg%) and aspartic acid (46.7–111 mg%) were major amino acids in the leaves. Total tannin contents were 0.90–2.10%, showing the highest amount in October. Forty-five volatile flavor components were identified in the leaves for the first time. These included four acids, 15 alcohols, seven aldehydes, two esters, three furans, nine hydrocarbons, two ionones, and three other compounds.

Non-Volatile Organic Acids, pH and Titratable Acidity Changes in Pineapple Fruit SlicesDuring Frozen Storage

Effects of freezing and frozen storage on pH, titratable acidity and non-volatile organic acids of two pineapple fruit cultivars, Smooth Cayenne and Red Spanish, were studied. Pineapple fruit was frozen as slices in a cold room at -18°C and stored at this temperature for a 12 month period. A negative correlation was found between pH and titratable acidity in the two cultivars throughout frozen storage (r = -0.67 for Smooth Cayenne and r = -0.71 for Red Spanish). Non-volatile organic acids were determined by high performance liquid chromatography. The major components were citric and L-malic acids. A high correlation was found between these two acids during frozen storage (r = 0.75 in Smooth Cayenne and r = 0.78 in Red Spanish). There were significant differences (P < 0.01) in pH and titratable acidity between the two studied varieties after a year of frozen storage. Significant differences (P ≤ 0.05) were found in pH values during frozen storage in cv Smooth Cayenne and in citric and L-malic acids in cv Red Spanish. Freezing preservation of pineapple fruit slices led to minimal chemical changes after a year of frozen storage.

NonVolatile Organic Acids, pH and Titratable Acidity Changes in Pineapple Fruit Slices During Frozen Storage

NonVolatile Organic Acids, pH and Titratable Acidity Changes in Pineapple Fruit Slices During Frozen Storage

Recovery of Nicotine and Non-Volatile Organic Acids from Turkish Tobacco Waste.

Tobacco waste consist of unusable parts of tobacco, obtained during the physical treatment in the production of cigarettes. Nicotine, oxalic, malic and citric acids, which are relatively more valuable than the other constituents of tobacco, can be extracted from the tobacco waste, using different solvents. There are many studies in the literature related to recovery of nicotine and organic acids from tobacco, using solvents