Determination of structural and mechanical properties, diffractometry, and thermal analysis of chitosan and hydroxypropylmethylcellulose (HPMC) films plasticized with sorbitol

In this work, the structural, mechanical, diffractometric, and thermal parameters of chitosan-hydroxypropylmethylcellulose (HPMC) films plasticized with sorbitol were studied. Solutions of HPMC (2% w/v) in water and chitosan (2% w/v) in 2% acetic acid solution were prepared. The concentration of sorbitol used was 10% (w/w) to both polymers. This solutions were mixed at different proportions (100/0; 70/30; 50/50; 30/70, and 0/100) of chitosan and HPMC, respectively, and 20 mL was cast in Petri dishes for further analysis of dried films. The miscibility of polymers was assessed by X-ray diffraction, scanning electronic microscopy (SEM), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The results obtained indicate that the films are not fully miscible at a dry state despite the weak hydrogen bonding between the polymer functional groups.

Biosensor for determination of glucose in real samples of beverages

A biosensor was developed for spectrophotometric determination of glucose concentrations in real samples of orange juice energetic drinks, and sport drinks. The biosensor consisted of glucose oxidase (GOD) and horseradish peroxidase (HRP) immobilized onto polyaniline activated with glutaraldehyde (PANIG). Immobilization parameters were optimized for GOD, and maximum immobilization yield was 16% when 5.0 mg of PANIG and 8.9 U prepared in 0.1 mol.L-1 sodium phosphate buffer (pH 7.0) reacted for 60 minutes at 4 °C with gentle stirring. The linear operational range for glucose determination using optimized operational parameters was between 0.05 and 6.0 mg.mL-1 with a very good reproducibility of response. The results obtained in the biosensor were compared with those obtained using free enzymes (commercial kits) and then validated through statistical analysis using the Tukey test (95% confidence interval).

Determination of acrolein, ethanol, volatile acidity, and copper in different samples of sugarcane spirits

Seventy-one samples of sugarcane spirits from small and average size stills produced in the northern and southern Minas Gerais (Brazil) were analyzed for acrolein using HPLC (High Performance Liquid Chromatography). Ethanol and copper concentrations and volatile acidity were also determined according to methods established by the Ministry of Agriculture, Livestock and Supply (MAPA). A total of 9.85% of the samples tested showed levels of acrolein above the legal limits, while the copper concentrations of 21.00% of the samples and the volatile acidity of 8.85% of the samples were higher than the limits established by the Brazilian legislation. The concentration of acrolein varied from 0 to 21.97 mg.100 mL-1 of ethanol. However, no significant difference at 5% of significance was observed between the samples produced in the northern and southern Minas Gerais. The method used for determination of acrolein in sugarcane spirits involved the formation of a derivative with 2,4-dinitrophenylhydrazine (2,4-DNPH) and subsequent analysis by HPLC.

Marolo (Annona crassiflora Mart.): a study of value chain and processing

This article aims to discuss the needs and problems of marolo value chain, as well as to evaluate the rehydration process of this fruit as a possibility of using it as a by-product during the interharvest growth periods. The study of the value chain included interviews with producers, handlers, and fruit and by-product sellers. In order to evaluate the rehydration process of this fruit, marolo was dehydrated using a conventional procedure and freeze-drying. The experiments were conducted in a completely randomized design and a triple factorial scheme (2 × 2 × 6). ANOVA was performed, followed by the Tukey's test (p < 0.05). Regression models were generated and adjusted for the time factor. The precariousness of the value chain of marolo was observed. The best procedure for marolo dehydration should be determined according to the intended use of the dehydrated product since the water-absorption capacity of the flour is higher and convective hot-air-drying is more effective in retaining soluble solids and reducing damage to the fruit. These results aim at contributing to the marolo value chain and to the preservation of native trees in the Brazilian savanna biome and can be used to analyze other underutilized crops.

Development and optimization of a HPLC-RI method for the determination of major sugars in apple juice and evaluation of the effect of the ripening stage

The sugars in apple juice prove its authenticity and its sensory and nutritional properties. The aim of this study was to develop and validate a simple analytical method using high performance liquid chromatography with refractive index detection (HPLC-RI) to determinate and quantify the sugars sucrose, D-glucose, D-fructose, and D-sorbitol polyol in apple juices, as well as to analyze the juices from the Fuji suprema and Lis Gala cultivars at three ripening stages. The analytical performance parameters evaluated indicated that the method was specific for the compounds analyzed, and the linearity of the calibration curves of sugars showed high correlation coefficients (close to 1.0). The limits of detection and quantification are consistent with recommendations available in the literature for this type of matrix. Sample preparation is simple and generates small amount of residues. Over 70% of the sugars were determined in the juices of apples at the pre-ripe stage, with an increase during senescence. This method is applicable for the determination of sugars in juices and evaluation of apple ripening.

Mathematical modeling of microwave dried celery leaves and determination of the effective moisture diffusivities and activation energy

Celery (Apium graveolens L. var. secalinum Alef) leaves with 50±0.07 g weight and 91.75±0.15% humidity (~11.21 db) were dried using 8 different microwave power densities ranging between 1.8-20 W g-1, until the humidity fell down to 8.95±0.23% (~0.1 db). Microwave drying processes were completed between 5.5 and 77 min depending on the microwave power densities. In this study, measured values were compared with predicted values obtained from twenty thin layer drying theoretical, semi-empirical and empirical equations with a new thin layer drying equation. Within applied microwave power density; models whose coefficient and correlation (R²) values are highest were chosen as the best models. Weibull distribution model gave the most suitable predictions at all power density. At increasing microwave power densities, the effective moisture diffusivity values ranged from 1.595 10-10 to 6.377 10-12 m2 s-1. The activation energy was calculated using an exponential expression based on Arrhenius equation. The linear relationship between the drying rate constant and effective moisture diffusivity gave the best fit.

Forced-air, vacuum, and hydro precooling of cauliflower (Brassica oleracea L. var. botrytis cv. Freemont): part I. determination of precooling parameters

The aim of the present study was to precool cauliflower using forced-air, vacuum and high and low flow hydro cooling methods. The weight of the precooled cauliflower heads (5000±5 g) was measured before they were placed in standard plastic crates. Cauliflower heads, whose initial temperature was 23.5 ± 0.5 ºC, were cooled until the temperature reached at 1 ºC. During the precooling process, time-dependent temperature and energy consumption were measured, and during vacuum precooling, the decreasing pressure values were recorded, and a curve of time-dependent pressure decrease (vacuum) was built. The most suitable cooling method to precool cauliflower in terms of cooling time and energy consumption was vacuum, followed by the high and low flow hydro and forced-air precooling methods, respectively. The highest weight loss was observed in the vacuum precooling method, followed by the forced-air method. However, there was an increase in the weight of the cauliflower heads in the high and low flow hydro precooling method. The best colour and hardness values were found in the vacuum precooling method. Among all methods tested, the most suitable method to precool cauliflower in terms of cooling and quality parameters was the vacuum precooling method.

Forced-air, vacuum, and hydro precooling of cauliflower (Brassica oleracea L. var. botrytis cv. Freemont): Part II. Determination of quality parameters during storage

Cauliflower heads, which were precooled using four different methods including vacuum, forced-air, and high and low flow hydro precooling, were stored under controlled atmosphere and room conditions. Controlled atmosphere conditions (CA) were as follows: 1°C temperature, 90 ± 5% relative humidity, and 0:21 [(%CO2:%O2) – (0:21) control] atmosphere composition. Room conditions (RC) were: 22±1°C temperature and 55-60% humidity. Various quality parameters of the cauliflower heads were assessed during storage (days 0, 7, 14, 21, 28, and 35) under controlled atmosphere and room conditions (days 0, 5, and 10). During storage, weight loss, deterioration rate, overall sensory quality score, hardness, and colour (L, a, b, C and α) were evaluated. In the present study, the strength and quality parameters of cauliflower under CA and RC conditions were obtained. Vacuum precooling was found to be most suitable method before cauliflower was submitted to cold storage and sent to market. Furthermore, the storage of cauliflower without precooling resulted in a significant decrease in quality parameters.

Development of a rapid method for the determination of antibiotic residues in honey using UPLC-ESI-MS/MS

Abstract An accurate, reliable and fast multianalyte/multiclass ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and validated for the simultaneous analysis of 23 pharmaceuticals, belonging to different classes amphenicols, sulfonamides, tetracyclines, in honey samples. The method developed consists of ultrasonic extraction followed by UPLC–ESI–MS/MS with electrospray ionization in both positive mode and negative mode. The influence of the extraction solvents and mobile phase composition on the sensitivity of the method, and the optimum conditions for sample weight and extraction temperature in terms of analyte recovery were extensively studied. The identification of antibiotics is fulfilled by simultaneous use of chromatographic separation using an Acquity BEH C18 (100 mm x 2.1 mm, 1.7 µm) analytical column with a gradient elution of mobile phases and tandem mass spectrometry with an electrospray ionization. Finally, the method developed was applied to the determination of target analytes in honey samples obtained from the local markets and several beekeepers in Muğla, Turkey. Ultrasonic-extraction of pharmaceuticals from honey samples is a well-established technique by UPLC–ESI–MS/MS, the uniqueness of this study lies in the simultaneous determination of a remarkable number of compounds belonging to 23 drug at the sub-nanogram per kilogram level.