Role of bioactive metabolites from Acremonium camptosporum associated with the marine sponge Aplysina fulva

Acremonium camptosporum, a fungus associated with the marine sponge Aplysina fulva, was collected from the isolated mid-Atlantic Saint Peter and Saint Paul Archipelago, Brazil, and was found to produce secondary metabolites that displayed antibacterial activities. Mass spectra data obtained by UPLC-ESI-MS/MS analyses of these extracts were compared to several databases and revealed the presence of several different cytotoxic acremonidins and acremoxanthones. The close association between the sponge and the fungi with its compounds could be of strategic importance in defending both from the high predation pressure and spatial competition in the warm-water scarps of the islands.

Pharmacokinetics, Pharmacodynamic Efficacy Prediction Indexes and Monte Carlo Simulations of Enrofloxacin Hydrochloride Against Bacterial Strains That Induce Common Clinical Diseases in Broiler Chickens

Pharmacokinetic parameters and efficacy prediction indexes (C_max/MIC₉₀ and AUC₀₋₂₄/MIC₉₀) of an enrofloxacin hydrochloride (ENR-HCl) veterinary product soluble in water were determined in healthy broiler chickens of both sexes after a single oral dose of ENR-HCl (equivalent to 10 mg ENR base/kg bw). Monte Carlo simulations targeting C_max/MIC₉₀ = 10 and AUC₀₋₂₄/MIC₉₀ =125 were also performed based on a set of MIC (minimum inhibitory concentration) values of bacterial strains that induce common clinical diseases in broiler chickens and that showed to be susceptible to ENR-HCl. Plasma concentrations of ENR and its main metabolite ciprofloxacin (CIP) were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma concentration-time curves were found to fit a non-compartmental open model. The ratio of the area under the plasma concentration-time curve (AUC) of CIP/ENR was 4.91%. Maximum plasma concentrations of 1.35 ± 0.15 μg/mL for ENR-HCl and 0.09 ± 0.01 μg/mL for CIP were reached at 4.00 ± 0.00 h and 3.44 ± 1.01 h, respectively. Areas under the plasma vs. time concentration curve in 24 h (AUC₀₋₂₄) were 18.91 ± 1.91 h × μg/mL and 1.19 ± 0.12 h × μg/mL for ENR-HCl and CIP, respectively. Using a microbroth dilution method, the minimum inhibitory concentration (MIC₉₀) values were determined for ENR-HCl for 10 bacterial strains (Mycoplasma gallisepticum, Mycoplasma synoviae, Avibacterium paragallinarum, Clostridium perfringens, Escherichia coli, Pseudomonas aeruginosa, Salmonella ser. Enteritidis, Salmonella ser. Gallinarum, Salmonella ser. Pullorum, and Salmonella ser. Typhimurium), which are the most common causes of infectious clinical diseases in broiler chickens. In summary, the PK/PD ratios and Monte Carlo simulation were carried out for ENR-HCl in poultry, which due to its solubility was administered in drinking water. The PK/PD efficacy prediction indexes and Monte Carlo simulations indicated that the ENR-HCl oral dose used in this study is useful for bacterial infections in treating C. perfringens (Gram-positive), E. coli and S. ser. Enteritidis (Gram-negative) and M. gallisepticum bacteria responsible for systemic infections in poultry, predicting a success rate of 100% when MIC ≤ 0.06 μg/mL for E. coli and S. ser. Enteritidis and MIC ≤ 0.1 μg/mL for M. gallisepticum. For C. perfringens, the success rate was 98.26% for MIC ≤ 0.12. However, clinical trials are needed to confirm this recommendation.

Development and application of a liquid chromatography-mass spectrometry method for the determination of sugars and organics acids in araza, ceriguela, guava, mango and pitanga

Abstract The intrinsic characteristics of many tropical fruits cause high post-harvest losses and prevent their commercialization as fresh fruits. Information about their composition is crucial for defining processing conditions and identifying opportunities for product development. However, the analytical methods generally used to quantify sugars and organic acids are costly and time-consuming. Simultaneous analysis by Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS/MS) is a very sensitive and reproducible technique, allowing for accurate simultaneous multi-analyte quantitation in complex systems. Thus, a LC-ESI-MS/MS Multiple Reaction Monitoring (MRM) method was developed using reverse phase column for detecting and quantifying sugars and some organic acids in only 4 min, in selected fruits as following: araza (Psidium cattleianum L.), ciriguela (Spondias purpurea L.), mango (Mangifera indicaL.), guava (Psidium guajava L.) and pitanga (Eugenia uniflora L.). All fruits had a similar concentration of glucose and fructose, except for pitanga that presented higher values of both. The content of citric, malic and tartaric acids was quantitated; some fruits stood out by their high content of organic acids, for instance, araza was rich in citric acid. The newly generated data on the composition of tropical fruits allowed establishing a correlation between the carbohydrate content and the physical properties of the fruit pulps, assist in product development.

Polyether ionophores residues in Minas Frescal cheese by UHPLC-MS/MS

An analytical method was developed and validated for the determination of three polyether ionophores (monensin, lasalocid, and salinomycin) in 60 samples of Brazilian Minas Frescal cheese by UHPLC-MS/MS. Linearity ranged from 1 to 8 μg kg^-1 for monensin and salinomycin, and from 0.50 to 4 μg kg^-1 for lasalocid. Limits of detection and quantitation were 0.50 μg kg^-1 and 1 μg kg^-1, respectively, for both monensin and salinomycin, and 0.25 μg kg^-1 and 0.50 μg kg^-1, respectively, for lasalocid. Recoveries were between 69% and 84% with coefficients of variation up to 16.28% for repeatability and 13.79% for intermediate precision. A total of 60 samples of Minas Frescal cheese were analysed and only monensin residues were found. Monensin was detected in 55% of the samples and quantified in 5 of them at mean levels varying from 1.00 to 1.73 μg kg^-1. The proposed method demonstrated the suitability for monitoring these substances in cheese.

Applicability of MALDI-TOF MS for determination of quinolone residues in fish

MALDI-TOF MS approach for determination of six quinolones residues in fillets of pangasius (Pangasionodon hypophthalmus) was studied, considering that is a very sensitive analytical technique with simple and high-throughput operation, contributing to knowledge regarding application of this technique to the determination of small-molecular-weight organic compound residues in foods. LIFT-MS/MS showed to be a successful approach to identify the presence of all quinolone residues in the fish fillet, at their respective MRL level. This study opens an important field of research for the development of simple and high-throughput bioanalytical screening methods for the determination of veterinary drug residues in foods.

Development and validation of an analytical method for the determination of 17β-estradiol residues in muscle of tambaqui (Colossoma macropomum Cuvier, 1818) by LC-MS/MS and its application in samples from a fish sexual reversion study

Tambaqui (Colossoma macropomum Cuvier, 1818) is the main native fish species farmed in Brazil, and 17β-estradiol (E₂) is a natural steroid hormone commonly used for the production of female fish monosex population, which, in tambaqui, shows a higher growth rate than the male. Thus, to assess whether the fish meat of treated tambaqui contains hormonal residue levels, a high-performance liquid chromatography coupled with electrospray tandem mass spectrometry (LC-MS/MS) method for the determination of E₂ residues in fish muscle was developed and validated. A QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) dispersive solid phase extraction method was used for the sample preparation. The chromatographic separation was performed in a Poroshel EC-18 reverse phase column. The mobile phase was a mixture of acetonitrile with 0.01% ammonium hydroxide (A) and water with 0.01% ammonium hydroxide (B). The ratio of A:B phases was 60:40 (v/v) used in an isocratic mode. The method validation was performed according to Commission Decision 2002/657/EC and Veterinary International Conference Harmonization (VICH GL49). Since matrix effects were observed, matrix-matched analytical curves are recommended for quantitation. The linearity, selectivity, intraday and interday precision, accuracy, decision limit, detection capability, and detection and quantitation limits of the method are reported. The limits of detection and quantitation were 0.3 ng/g and 1.0 ng/g, respectively. At these limits and slaughtering fish 7 months after the end of the treatment, the muscle of tambaqui did not show detectable hormone residue level. Thus, consumption of tambaqui edible tissue from fish treated with E₂ for the purpose of sexual reversion is unlikely to represent a risk associated with the exposure of human subjects as residue levels of this hormone are not detected in the fish muscle.

Evaluation of the leaching of florfenicol from coated medicated fish feed into water

Florfenicol is one of the most-used antimicrobial agents in global fish farming. Nevertheless, in most countries, its use is not conducted in accordance with good practices. The aim of this work was to evaluate the leaching of florfenicol from coated fish feed into the water. Analytical methods were developed and validated for the quantitation of florfenicol in medicated feed and water by UHPLC-MS/MS. Florfenicol residues in the water were quantified after 5- and 15-min exposures of the medicated feed in the water at 22 and 28 °C and at pH 4.5 and 8.0. The influence of pellet size and three coating agents (vegetable oil, carboxymethylcellulose, and low-methoxylated pectin) on the leaching of the drug was also assessed. Pellet size, coating agent, water temperature, and time of exposure significantly (p < 0.05) affected florfenicol leaching, while water pH did not interfere with the leaching. Coating with vegetable oil was the most efficient method to reduce florfenicol leaching, while coating with carboxymethylcellulose presented the highest leaching (approximately 60% after 15 min at 28 °C). Thus, the coating agent has a significant effect on the florfenicol leaching rate and, consequently, on the necessary dose of the drug to be administered. Moreover, it is worth mentioning that higher florfenicol leaching will pose a greater risk to environmental health, specifically in terms of the development of bacteria resistant to florfenicol. Additional studies are needed with other polymers and veterinary drugs used in medicated feed for fish farming.

Depletion study, withdrawal period calculation and bioaccumulation of sulfamethazine in tilapia (Oreochromis niloticus) treated with medicated feed

The residue depletion of sulfamethazine (SMZ) was evaluated in tilapia (Oreochromis niloticus) after 11 days of administration of medicated feed containing SMZ, at the dose of 422 mg/kg body weight (bw). The determination of SMZ in feed and tilapia fillet was carried out using the QuEChERS approach for sample preparation, and high performance liquid chromatography with diode array detector (HPLC-DAD) and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) for quantitation, respectively. Both methods were validated based on international and Brazilian guidelines and shown to be suitable for the intended purposes. The withdrawal period to reach the maximum residue level (MRL) of 100 μg/kg, according to the European Union (EU) legislative framework to all substances belonging to the sulfonamide (SA) group (EU, 2010), was 10 days (260 °C-day). After treatment, the maximum level of SMZ accumulation in the tilapia muscle was 1.6 mg/kg. SMZ was shown to be quickly excreted by tilapia. Thus, considering the acceptable daily intake of SMZ established by the Codex Commission (0-0.05 mg/kg bw), and a factor of 5 times the upper amount of fish consumption in Brazil (38 kg/year), this study showed that there is a low risk of adverse effects to consumers. This study offers subsidies not only for the establishment of public policies with regard to the use of veterinary drugs currently not allowed in a country by their legal legislative framework for fish farming, but also to fish producers for the proper handling to ensure safe fish fillets.

Multiresidue Method for Quantification of Sulfonamides and Trimethoprim in Tilapia Fillet by Liquid Chromatography Coupled to Quadrupole Time-of-Flight Mass Spectrometry Using QuEChERS for Sample Preparation

A multiresidue method for detecting and quantifying sulfonamides (sulfapyridine, sulfamerazine, sulfathiazole, sulfamethazine, sulfadimethoxine, sulfamethoxazole, and sulfamethoxypyridazine) and trimethoprim in tilapia fillet (Oreochromis niloticus) using liquid chromatography coupled to mass spectrometry was developed and validated. The sample preparation was optimized using the QuEChERS approach. The chromatographic separation was performed using a C18 column and 0.1% formic acid in water and acetonitrile as the mobile phase in the isocratic elution mode. Method validation was performed based on the Commission Decision 2002/657/EC and Brazilian guideline. The validation parameters evaluated were linearity (r ≥ 0.99); limits of detection (LOD) and quantification (LOQ), 1 ng·g^-1 and 5 ng·g^-1, respectively; intraday and interdays precision (CV lower than 19.4%). The decision limit (CCα 102.6-120.0 ng·g^-1 and 70 ng·g^-1 for sulfonamides and trimethoprim, respectively) and detection capability (CCβ 111.7-140.1 ng·g^-1 and 89.9 ng·g^-1 for sulfonamides and trimethoprim, respectively) were determined. Analyses of tilapia fillet samples from fish exposed to sulfamethazine through feed (incurred samples) were conducted in order to evaluate the method. This new method was demonstrated to be fast, sensitive, and suitable for monitoring sulfonamides and trimethoprim in tilapia fillet in health surveillance programs, as well as to be used in pharmacokinetics and residue depletion studies.

Moxidectin residues in lamb tissues: Development and validation of analytical method by UHPLC-MS/MS

The development and validation of a throughput method for the quantitation of moxidectin residues in lamb target tissues (muscle, kidney, liver and fat) was conducted using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). To achieve higher recovery of the analyte from the matrices, a modified QuEChERS method was used for sample preparation. The chromatographic separation was achieved using a Zorbax Eclipse Plus C18 RRHD column with a mobile phase comprising 5mM ammonium formate solution +0.1% formic acid (A) and acetonitrile +0.1% formic acid (B) in a linear gradient program. Method validation was performed based on the Commission Decision 2002/657/EC and VICH GL49. To quantify the analyte, matrix-matched analytical curves were constructed with spiked blank tissues, with a limit of quantitation of 5ngg^-1 and limit of detection of 1.5ngg^-1 for all matrices. The linearity, decision limit, detection capability accuracy, and inter- and intra-day repeatability of the method are reported. The method was successfully applied to incurred lamb tissue samples (muscle, liver, kidney and fat) in a concentration range from 5 to 200μgkg^-1, which demonstrated its suitability for monitoring moxidectin residues in lamb tissues in health surveillance programs, as well as for pharmacokinetics and residue depletion studies.

Monosodium glutamate as a tool to reduce sodium in foodstuffs: Technological and safety aspects

Sodium chloride (NaCl) is the most commonly used ingredient to provide salty taste to foods. However, excess sodium in the bloodstream has been associated with the development of several chronic noncommunicable diseases. In order to limit sodium intake to levels considered safe, the World Health Organization (WHO) recommends for adults a daily intake of not more than 5 g of NaCl (less than 2 g of sodium). One of the strategic actions recommended by the Pan American Health Organization (PAHO) to reduce sodium intake is reformulation of processed foods. This recommendation indicates there is an urgent need to find salt substitutes, and umami compounds have been pointed as an alternative strategy. Like salty, umami is also a basic taste and the major compound associated to umami is monosodium L-glutamate (MSG). The available scientific data on the toxicity of MSG has been evaluated by scientific committees and regulatory agencies. The Joint FAO/WHO Expert Committee on Food Additives and the Scientific Committee on Food of the European Commission established an acceptable daily intake (ADI) not specified, which indicated that the substance offers no health risk when used as a food additive. The United States Food and Drug Administration and the Federation of American Societies for Experimental Biology classified MSG as a Generally Recognized as Safe (GRAS) substance. In this paper, an overview about salty and umami taste physiology, the potential applications of MSG use to reduce sodium content in specific industrialized foods and safety aspects of MSG as food additive are presented.

Antibacterial Compounds from Marine Bacteria, 2010-2015

This review summarizes the reports on antibacterial compounds that have been obtained from marine-derived bacteria during the period 2010-2015. Over 50 active compounds were isolated during this period, most of which (69%) were obtained from Actinobacteria. Several compounds were already known, such as etamycin A (11) and nosiheptide (65), and new experiments with them showed some previously undetected antibacterial activities, highlighting the fact that known natural products may be an important source of new antibacterial leads. New broad-spectrum antibacterial compounds were reported with activity against antibiotic resistant Gram-positive and Gram-negative bacteria. Anthracimycin (33), kocurin (66), gageotetrins A-C (72-74), and gageomacrolactins 1-3 (86-88) are examples of compounds that display promising properties and could be leads to new antibiotics. A number of microbes produced mixtures of metabolites sharing similar chemical scaffolds, and structure-activity relationships are discussed.

L-glutamate: a key amino acid for senory and metabolic functions

Glutamic acid or its ionic form L-glutamate (GLU) is one of the most abundant amino acids in nature and it plays important functions at the cellular and systemic levels. For instance, in the intestine and liver, GLU is a source of energy and is the precursor of key biological molecules. At the central nervous system of mammals, GLU acts as an excitatory neurotrausmitter due to the interaction with specific receptors. In addition, GLU has been related with short- and long-term potentiation, memory and the learning. Furthermore, consumption of GLU or its monosodium salt (monosodium glutamate, MSG) as a food additive is responsible for the umami taste. The consumption of MSG has been considered safe for different agencies responsible for the evaluation of the safe use of food additives, which have establish an Acceptable Daily Intake (ADI) "not specified", or classified as Generally Recognized Safe Substance (GRAS). This review focuses on important metabolic aspects of GLU and its role in food tasting and MSG safety.

Streptomycin and dihydrostreptomycin residues in bovine milk from the Brazilian retail market

Pasteurised bovine milk from retail markets in the State of São Paulo, Brazil, was analysed for the presence of streptomycin (STP) and dihydrostreptomycin (DHSTP) residues. An ELISA kit was used for screening and a LC-APCI-MS/MS QToF method for confirmatory analysis. Both methods were intra-laboratory validated and found suitable for screening and confirmatory testing, respectively, for STP and DHSTP residues in pasteurised bovine milk at concentration levels below the maximum residue limit (MRL) established for these substances (200 µg kg(-1) expressed as the sum of the concentrations of STP and DHSTP). No residues of STP and DHSTP at detectable levels were found in the analysed samples (n = 299).

Enrofloxacin assay validation and pharmacokinetics following a single oral dose in chickens

The pharmacokinetics of enrofloxacin (ENRO), a fluoroquinolone antimicrobial agent, was studied in male broiler chickens (Cobb) after single oral administration of 10 mg of ENRO/kg b.w. A high-performance liquid chromatography-photodiode array detector (DAD) (HPLC-DAD) method was developed and validated and used for quantitation of ENRO and its major metabolite ciprofloxacin in plasma. The HPLC analyses were carried out using a cationic-octadecyl mixed column and 0.05 mol/L phosphate buffer (pH 2.5)/acetonitrile as mobile phase. The sample preparation of plasma consisted of the precipitation of proteins followed by solid phase extraction on cationic-octadecyl mixed cartridges. The method was validated considering linear range, linearity, selectivity, sensitivity, limit of detection (LOD), limit of quantitation (LOQ), intra- and inter-day precisions and accuracy. The LOD and LOQ for both fluoroquinolones were 60 and 200 ng/mL for plasma. The plasma concentration vs. time graph was characteristic of a two-compartment open model. The maximal plasma concentration of 1.5 +/- 0.2 mg/mL was achieved at 9 +/- 2 h. The elimination half-life and the mean residence time of ENRO were 1.5 +/- 0.2 and 15.64 h, respectively. The area under the concentration-time curve was calculated as 35 +/- 4 mgxh/mL.

Occurrence of ivermectin in bovine milk from the Brazilian retail market

High-performance liquid chromatography (HPLC) with fluorescence detection was used for the quantification of ivermectin residues in bovine milk intended for human consumption. After liquid-liquid extraction of ivermectin and purification of the extract, the compound was derivatized with 1-methylimidazol in N,N-dimethyl formamide to form a fluorescent derivative, which was separated by HPLC, using reversed-phase C18, with methanol : water (96 : 4 v/v) mobile phase at a flow rate 0.7 ml min-1. The excitation and emission wavelengths of the fluorescence detector were adjusted at 360 and 470 nm, respectively. The linearity of the method was in the range 10-100 ng ivermectin ml-1. Based on a sample of 5.0 ml, the limit of detection and the limit of quantification for ivermectin in milk were 0.6 and 2 ng ml-1, respectively. The recovery rate varied from 76.4 to 87.2%, with an average of 77.9 +/- 3.2%, at four fortification levels. The inter-day precision of the method was 13% (n = 5). Of 168 samples analysed, 17.8% contained ivermectin above the limit of quantification. Nevertheless, none of the samples contained ivermectin above the maximum residue limit (10 ng ml-1) established by the Brazilian Ministry of Agriculture.

Plasticizers in Brazilian food-packaging materials acquired on the retail market

Packaging materials intended for direct food contact were acquired on the Brazilian retail market and analysed for their plasticizer content. Analyses were carried out by gas chromatography with flame ionization detection. Di-2-ethyl-hexyl adipate (DEHA), di-2-ethyl-hexyl phthalate (DEHP) and di-iso-decyl phthalate (DIDP) plasticizers were identified in films and closure seals in concentrations ranging from 12 to 19% (w/w), 15 to 44% (w/w) and 10 to 11% (w/w), respectively. Brazilian regulations state that for use with foods with a fat content above 5%, the levels of DEHP and DIDP in the plastic material should be no greater than 3%. The results obtained demonstrate a lack of conformity. It would be advisable to include information on the labels of packaging materials about their restrictions of use in order to advise manufacturers and consumers about their proper usage.

Evaluation of the nitrate content in leaf vegetables produced through different agricultural systems

The nitrate content of leafy vegetables (watercress, lettuce and arugula) produced by different agricultural systems (conventional, organic and hydroponic) was determined. The daily nitrate intake from the consumption of these crop species by the average Brazilian consumer was also estimated. Sampling was carried out between June 2001 to February 2003 in Campinas, São Paulo State, Brazil. Nitrate was extracted from the samples using the procedure recommended by the AOAC. Flow injection analysis with spectrophotometric detection at 460 nm was used for nitrate determination through the ternary complex FeSCNNO+. For lettuce and arugula, the average nitrate content varied (p < 0.05) between the three agricultural systems with the nitrate level in the crops produced by the organic system being lower than in the conventional system that, in turn, was lower than in the hydroponic system. For watercress, no difference (p < 0.05) was found between the organic and hydroponic samples, both having higher nitrate contents (p < 0.05) than conventionally cultivated samples. The nitrate content for each crop species varied among producers, between different parts of the plant and in relation to the season. The estimated daily nitrate intake, calculated from the consumption of the crops produced by the hydroponic system, represented 29% of the acceptable daily intake established for this ion.

LC-APCI-MS-MS methodology for determination of glybenclamide in human plasma

A liquid chromatographic/atmospheric pressure chemical ionization tandem mass spectrometric method (LC-APCI-MS-MS) for the determination of glybenclamide in human plasma is described. Glypizide, an analogue of glybenclamide, was used as internal standard. The analyte was extracted from plasma with diethyl ether/dichloromethane (70:30 v/v). The chromatography uses C18 and 0.01 mol L(-1) acetic acid/acetonitrile (20:80 v/v) as stationary and mobile phase, respectively. Quantitation was preformed by using multiple reaction monitoring (MRM) of the precursor ion (m/z 494.2-->368.8) and the related product ion (m/z 446.0-->347.3) using the internal standard method. The analytical curve was linear in the range 1-300 ng mL(-1), and for a 400-microL sample of human plasma, the limit of determination of the method was 1 ng mL(-1). The coefficients of variation of the method for intra-assay (within-run precision) and inter-assay (between-run precision) were less than 10%. The method was shown to be suitable for pharmacokinetic studies.

Aspectos de legislação do mercado internacional de embalagens plásticas para alimentos

RESUMO: Neste artigo de revisão são abordados aspectos de legislação relacionados ao uso seguro de componentes de materiais de embalagem plástica para alimentos. São apresentados os sistemas de regulamentação adotados no Brasil, Estados Unidos da América, União Européia e MERCOSUL.

Estabilidade térmica de embalagens de poli (tereftalato de etileno (PET): determinação de Oligômeros

RESUMO: Embalagens plásticas para alimentos contendo poli(tereftalato de etileno (PET) foram submetidas a diversas condições de aquecimento. Oligômeros foram identificados por cromatografia líquida de alta eficiência acoplada à espectrometria de massas, quantificados e usados como parâmetro de avaliação da estabilidade térmica do PET. Pequenas variações foram verificadas na distribuição dos oligômeros unicamente nas amostras aquecidas a 230 °C, o que sugere estabilidade térmica do PET nas condições de aquecimento utilizadas. Os resultados obtidos indicam que o uso do polímero é adequado para utilização como material de embalagem para alimentos a serem aquecidos em fornos convencionais ou de microondas.

Comparison of Enzymic, Gas-Liquid Chromatographic, and High Performance Liquid Chromatographic Methods for Determining Sugars and Organic Acids in Strawberries at Three Stages of Maturity

Free sugars and major nonvolatile organic acids present in strawberries at 3 degrees of ripeness were determined by 3 analytical methods: enzymic, gasliquid chromatographic, and high performance liquid chromatographic. Results showed that variability in sugar composition due to both degree of ripeness and method of analysis was greater for sucrose than for glucose and fructose. Sucrose was almost completely hydrolyzed in the overripe fruit. Acid results showed that there was little variation in citric acid levels due to ripeness or method of analysis; malic acid, however, decreased greatly in overripe fruit. Malic acid also showed high variability due to method of analysis. The glucose:fructose ratios for the underripe, ripe, and overripe fruit were 0.86,0.92, and 0.60, respectively. The citric:malic ratios were 1.58, 2.39, and 14.86 for the underripe, ripe, and overripe stages, respectively.