Chemometric Analysis of <Superscript>1</Superscript>H NMR Fingerprints of <Emphasis Type="Italic">Coffea arabica</Emphasis> Green Bean Extracts Cultivated under Different Planting Densities

High planting density has been used to increase coffee production but there are few studies related to the variations it provokes in metabolite compositions. The use of ¹H NMR data associated with chemometric techniques allows the determination of metabolic fingerprints and verification of metabolic changes when coffee is subjected to high planting densities. The aim of this work is to investigate ¹H NMR spectral data of green bean extracts of Coffea arabica cv. IAPAR 59 grown in a square pattern at two planting densities, 6000 and 10,000 plants ha^?1. Thirty extracts were obtained using a simplex centroid design with four solvents (ethanol, acetone, dichloromethane, and hexane). The lyophilized extracts were dissolved in DMSO-d₆ to obtain the ¹H NMR spectra. The spectral data were analyzed with principal component (PCA) and cluster analyses (CA). Significant differences between ethanolic and non-ethanolic extracts were found by PCA. Only the ethanolic mean spectrum showed characteristic chemical shifts of sugars and trigonelline. Acetone extracts were separated by cluster analysis.     

Temperature Control of a Thermal Plasma Torch with Inductive Coupling Using the Arduino Board

Plasma torch is a device that transforms electrical energy into heat carried by a gas and its safe operation is necessary to control her temperature. This paper presents the use of the Arduino board in temperature control of a plasma torch through fuzzy control. The plasma torch of this project was built so that a flow of water can circulate through your body, allowing its cooling. The cooling system mounted consists of one radiator, one expansion vase, one water pump and one temperature sensor. The heated water coming the plasma torch is passed by the temperature sensor. This is converted in a voltage and read by an analog input port of the Arduino. This processes the information received and makes the decision to turn on/off the radiator fan and/or powered the frequency inverter water pump to control the temperature. The graph of the fuzzy control showed an oscillation between 104 °F to 122 °F around the chosen reference 113 °F. The results show that it is possible to control the temperature of a plasma torch using the Arduino board and fuzzy logic.     

Continuous catalyst-free methanolysis and ethanolysis of soybean oil under supercritical alcohol/water mixtures

This work investigates and compares the reaction performance of soybean oil transesterification under supercritical methanol and ethanol, in a continuous catalyst-free process, as a cleaner alternative to conventional chemically catalyzed process. Reactions were performed in a tubular reactor, at 20 MPa, with oil to alcohol ratio of 1:40, varying the temperature in the range from 250 °C to 350 °C, and at two levels of water concentrations, 0 and 10 wt%. Although both processes proceeded with a relatively high reaction rate, conversion achieved by methanolysis was higher than that obtained by ethanolysis. Water positively affected both process: higher ester content and triacylglycerols depletion occurred when 10 wt% water was used compared with anhydrous conditions. Temperature increase favored the conversion of soybean oil to the corresponding methyl or ethyl esters, although temperatures above 300 °C increased the fatty acid degradation degree, a phenomenon responsible for the low ester contents obtained at the highest temperatures and lowest flow rates studied.     

Isolation and characterisation of pectic substances from murta (Ugni molinae Turcz) fruits

Cell walls polysaccharides from murta fruit (Ugni molinae Turcz), an endemic Chilean species with relevant food uses, were fractionated by water, ammonium oxalate, hot diluted HCl and cold diluted NaOH extractions. The polysaccharide fractions were analysed for monosaccharide composition and physicochemical properties. Pectic substances were found in all extracts, but mainly in the oxalate and acid soluble fractions, in which they appear as homogalacturonan polymers. Murta pectin was further extracted by hot diluted acid treatment using industrial conditions, yielding 30% by weight of dry fruit. The polymer showed similar composition and physicochemical properties to those of commercial citrus pectin, presenting a galacturonic acid content of 70.9% (w/w), a molecular weight of 597 kDa, and a methoxylation degree of 57%. The FT-IR spectrum of murta pectin suggests the presence of ferulic acid residues on its structure and the NMR analysis confirmed the structure of this polysaccharide. It is concluded that murta fruit can be considered as a valuable source of high quality pectin.     

Confined melting in deformable porous media: A first attempt to explain the graphite/salt composites behaviour

This paper deals with phase change in composite materials made of graphite and a phase-change material (PCM). The composites are manufactured by compressing a solid mixture of salt and graphite particles. In previous works, the interest of such materials for thermal energy storage at high temperature has been highlighted. They are characterized by quite high energy storage capacity as well as high thermal conductivity. However, first melting/crystallization of these composites could lead to significant salt leakage and shows some a priori unexpected features like melting over a range of temperature instead of at constant temperature and significant loss of heat storage capacity. A poro-thermo-elastic analysis is carried out in this paper for understanding salt melting within the graphite matrices and for proposing reliable ways for composite materials improvement. An intentionally simple think-model, based on mass and energy conservation equations, pressure-dependent liquid–crystal equilibriums, linear elasticity laws and Poiseuille-like flow, is proposed. In spite of the simplicity, the model turns out to be apt to explain main macroscopic features of materials melting as observed in calorimetric tests. The influence on melting dynamics of parameters like the heating rate, the pore-wall rigidity and thickness, the salt volume expansion and the pore connectivity is investigated and several ways for composite materials improvements are discussed.     

Effect of chitosan coating in preventing deterioration and preserving the quality of fresh‐cut papaya ‘Maradol’

BACKGROUND: Chitosan can form antimicrobial, semi‐permeable barriers that limit gas exchange and reduces water loss in fruits. Consumer interest in fresh‐cut papaya fruit is leading to increasing demand because of its sensorial and antioxidant properties. However, papaya is a highly perishable product that is prone to loss of weight, loss of firmness and microbial attack. The aim of this study was to evaluate the effect of chitosan coatings on the overall quality of fresh‐cut papaya. Chitosan coatings of low (LMWC), medium (MMWC) and high (HMWC) molecular weights, at concentrations of 0.01 and 0.02 g mL^?1, were applied to fresh‐cut papaya cubes. The treated cubes were stored at 5 °C and changes in quality were evaluated. RESULTS: MMWC maintained the highest color values (L* and b*) and firmness. Chitosan coatings suppressed mesophilic plate count, and the growth of molds and yeast, compared to controls. The MMWC coatings at 0.02 g mL^?1 resulted in the highest antimicrobial activity and decreased the activity of the enzymes polygalacturonase and pectin methylesterase, followed by low and high MW chitosan coatings at 0.02 g mL^?1. CONCLUSION: The application of the MMWC treatment at 0.02 g mL^?1 could be used to reduce deteriorative processes, maintain quality and increase the shelf life of fresh‐cut papaya stored at 5 °C. Copyright © 2008 Society of Chemical Industry     

Non-conventional high-pressure extraction process: A comparative study for astaxanthin recovery from Xanthophyllomyces dendrorhous

Xanthophyllomyces dendrorhous is one of the most attractive natural sources of astaxanthin. The yeast produces the compound intracellularly, therefore, it is necessary to evaluate cell rupture methods using clean and efficient technologies for its extraction and it subsequent use in industries. At present work, two non-conventional high-pressure extraction methods were evaluated for astaxanthin recovery: Supercritical fluid extraction and microfluidisation. Results: Effect of pressure (15, 30, and 45 Megapascals; MPa), Temperature (313 and 343 °K) and usage of co-solvent were studied in supercritical extraction process, meanwhile the effect of microfluidisation process (five stages and 160 MPa) for cell rupture and its combination with conventional technics (lithic enzymes, glass beads and ultrasonication) for the recovery of astaxanthin were evaluated. Supercritical fluid extraction presented a higher astaxanthin recovery, 54% yield extraction, at 32.5 MPa and 313 °K, and using ethanol as co-solvent, compared to a 31% yield extraction by mean microfluidisation process at 160 MPa combined with 15 min of sonication (amplitude of 80%).     

Antioxidant packaging development and optimization using agroindustrial wastes

The increasing use of non-biodegradable materials and the difficulty in recycling most of the available packaging have been pushing the development of biodegradable packaging. In this study, the potential uses of agroindustrial wastes to produce biodegradable films with antioxidant capacity were investigated. Starch films were produced by casting method using bran from jaboticaba peel, mango peel, and broccoli stalk. The influence of the concentration or type of bran in the properties of the films was evaluated through a central composite design. The results were analyzed by response surface and desirability function. Except for elongation and water solubility, the fitted equations were predictive in all studied properties. The films prepared from a higher concentration of mango peel exhibited better antioxidant capacity, while the broccoli stalk had no significant effect on antioxidant properties. The optimal formulation of the film (2.8% of jaboticaba peel and 20.0% of mango peel) and their predicted response variables (0.8 MPa for tensile strength, 40.0 MPa for Young's modulus, 4.5 mg/ml for IC₅₀, and 41.6% for inhibition percentage) were defined according to the results. The optimization was satisfactory and the film presented high antioxidant capacity and moderate mechanical properties, proving to be an alternative to replace plastic packaging.