Effect of Peroxide Concentration on the Modification of the LLDPE: Statistical Experimental Design and Thermal Properties

Summary The effect of small concentrations of dicumyl peroxide (DCP) on the modification of a linear low density polyethylene (LLDPE) during a reactive extrusion process was investigated. The experiments were arranged in a two level factorial design in order to evaluate the effect of temperature zones (X₁), peroxide concentration (X₂) and screw rpm (X₃) on the modification of LLDPE. The melt flow index (MFI) was used as a response variable. It was verified that the thermal properties, crystalline melting temperature (T_m), the heat of fusion (Hmelt) and the crystallinity degree (X%) decrease with the increasing of the peroxide concentration. The crystallization temperature (T_c) increased up to 0.05% w/w peroxide, whereafter the level stays almost constant. The gel content of the samples however indicated that a three-dimensional network was negligible in the experimental conditions used.     

Plan directeur d'exploitation des carrieres

The necessity of planning the activities related to quarries developed in the metropolitan area of Sao Paulo, in accordance with the directions fixed by the metropolitan planning led to the preparation of a PDM-PLANO DIRECTOR DE MINERAÇAO-(guiding Plan for Quarrying). This project includes contributions from SNM—Secretaria dos negocios metropolitanos do estado de Sao Paulo—as well as from D.N.P.M.—Departmento Nacional da Produçao Mineral; from Emplasa—Empresa metropolitana de planejamento da grande Sao Paulo and from C.P.R.M.—Companhia de Pesquisa de Recursos Minerais. This work was a natural consequence of what was agreed upon between S.N.M. and D.N.P.M., on september the 28^th, 1976. Such an agreement proved to be necessary when the conflicts between the quarrying activities and the plans for use and occupation of the metropolitan soils tended to increase, as there was an incompatibility between quarrying activities development and the areas which had been selected for agriculture, implantation of industrial districts, urban expansion or even for environmental protection. The elaboration of the PDM required hard field work including a survey of mineral potential areas, the situation of the market; a check-up of local conditions for quarrying; the methods of quarrying which were used and the possibilities of recovering the mined areas. It also requried experts from different fields, such as architects, civil and mining engineers, geoligists, geographers and lawyers who worked together, in an attempt to find an integrated solution for the problem. The execution and implantation of the PDM led to the conclusion that quarrying activities had to be considered as a significant way of using the soil, contrary to what had been done so far. It also tried to integrate it with other uses of the soil, in the metropolitan planning.     

Volatile Compound and Sensory Analysis for the Characterization of an Italian White Wine from “Inzolia” Grapes

The research evidences the importance of linking chemical and sensory data for the wine characterization; in particular, the Italian white wine made from Inzolia grapes has been considered. Inzolia is one of the most widespread native white grapes in Sicily (Italy), and wine samples from two different areas (Monreale and Sambuca di Sicilia) have been analyzed. A headspace solid-phase microextraction/gas chromatography–mass spectroscopy method has been developed, and 56 volatile components, esters, fatty acids, alcohols, and terpenes have been identified; the method allows also the quantification of the main components, namely, ethyl octanoate (banana, fruit, fat) (257.2–541.6 mg/l) and ethyl decanoate (fruity, oily, floral; 171.8–272.0 mg/l). A good repeatability in terms of retention times and peak areas resulted. Sensory analysis was performed by ten trained judges that evaluated eight attributes: two referring to appearance (yellow color and yellow reflex), four referring to aroma (fruity, banana, ripened apple, and floral), and two referring to oral perception (acid and pungent). The volatile constituents and the aroma sensory attributes were in agreement.     

Bacillus cereus,Bacillus thuringiensis and Bacillus mycoides differentiation using a PCR-RE technique

A method was developed to differentiate between Bacillus cereus, Bacillus mycoides and Bacillus thuringiensis using the polymerase chain reaction combined with a restriction endonuclease (PCR-RE) technique. This fast and simple protocol, applied to pure culture strains, was developed using the gyrB DNA sequence, as previously proposed by other authors. Strains from international collections were used to optimize the method which was then applied to the identification of strains isolated from food samples. Amplifications were specific for the B. cereus group. Only Staphylococcus aureus gave the same size PCR product, but it was easily differentiated from strains in the B. cereus group by using restriction analysis, based on digestion with the RsaI, Sau3AI and EcoRI endonucleases. Specific amplifications and good differentiations were obtained using pure strains, suggesting the possibility of using the method described to identify the B. cereus group directly in food samples.     

A New Label-Free Impedimetric Affinity Sensor Based on Cholinesterases for Detection of Organophosphorous and Carbamic Pesticides in Food Samples: Impedimetric Versus Amperometric Detection

Due to their increasing use in agriculture, the presence of pesticide residues in food and water currently represents one of the major issues for the food safety. Among the pesticides, organophosphate and carbamate species are the most used, and their toxicity is mainly due to their inhibitory effect on acetylcholinesterase (AChE). For this reason, a monoenzymatic acetylcholinesterase impedimetric biosensor was developed in order to sensitively detect carbamate and organophosphate compounds with a very fast response. The working principle of the AChE biosensor exploits the capability of carbamate and organophosphate pesticides to form a stable complex with the enzyme, which causes an impedimetric change. The impedimetric biosensor showed a linearity between 5 and 170 ppb for carbamates and 2.5–170 ppb for organophosphate compounds, with a reproducibility (RSD%) interelectrode equal to 4.8 and 3.1% for organophosphates and carbamates, respectively. Moreover, the common amperometric evaluation of AChE inhibition degree was correlated to the impedimetric changes of the electrode surface, showing a good correlation (R ² = 0.99 for carbamates and R ² = 0.98 for organophosphates) between the two methods. In contrast to amperometric evaluation that needs a response time of 20 min, impedimetric detection requires only 4 min. Finally, the impedimetric biosensor was used to measure carbaryl and dichlorvos spiked in different concentrations in tap water and lettuce samples, showing a recovery near to 100% for all concentrations and for both pesticides.     

Effects of microwave and hot‐air drying methods on colour, β‐carotene and radical scavenging activity of apricots

The effects of drying by microwave and convective heating at 60 and 70 °C on colour change, degradation of β‐carotene and the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH) scavenging activity of apricots were evaluated. Microwave heating reduced significantly the drying time (up to 25%), if compared with convective one, also owing to the higher temperature reached during the last phase of the process, as monitored by infrared thermography. Colour changes of apricot surface, described with lightness and hue angle, in both drying methods followed a first‐order reaction (0.927 ≤ R² ≤ 0.996). The apricots dried by microwave were less affected by the darkening phenomena. The evolution of β‐carotene in fresh apricots (61.2 ± 5.6 mg kg^?1 d.w.) during the drying highlighted a wider decrease (about 50%) when microwave heating was employed for both the temperatures used. Radical scavenging activity increased (P < 0.05) in all dried samples except for hot‐air dried apricots at 60 °C.     

Bioactive action of β‐glucosidase enzyme of Bifidobacterium longum upon isoflavone glucosides present in soymilk

Bioconversion of isoflavone glucosides and antioxidant activity by probiotic strain (Bifidobacterium longum) during soymilk fermentation was investigated, as well as partial characterisation of the produced enzyme β‐glucosidase. The enzyme has higher affinity for genistin than for other substrates assayed. Maximum activity occurred at 42 °C and at pH 6.0; keeping 70–80% of activity for 60 days stored at low temperatures. Bifidobacterium longum grew well in soymilk (8.26 log CFU mL^?1 and pH of 3.9 at 24 h) and were produced in good quantities of organic acids. High hydrolysis degree of isoflavone glucosides (81.2%) was observed at 24 h. Enhancements in bioactivity were assessed in fermented soymilk by monitoring the radical‐scavenging activity, antioxidant activity and DNA protective action. The use of probiotic Bifidobacterium strain as β‐glucosidase producer increased bioactive isoflavone content and demonstrated that this enzyme plays a key role in the bioavailability of soymilk isoflavones, reducing the bioconversion time compared to other studies.