Determination of bisphenol A in, and its migration from, PVC stretch film used for food packaging

Bisphenol A (BPA) is used as an additive in polyvinyl chloride (PVC) products, including stretch films used for food packaging. The BPA contents were investigated of several brands of stretch film bought locally but marketed internationally or throughout Spain and which were presumably produced at different manufacturing plants. Their major components were identified by FTIR (Fourier Transform Infrared Spectrometry) and horizontal attenuated total reflectance, and the migration of BPA from these materials into the standard European Union food simulants was determined by high-performance liquid chromatography (HPLC) using both fluorescence (FL) and ultraviolet (UV) detection, the identity of the analyte being confirmed by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). The two HPLC detection methods had different detection limits (30 μg l^-1 for UV, 3 μg l^-1 for FL), but afforded virtually identical BPA determinations for the samples tested. BPA contents ranging from 40 to 100 mg kg^-1 were found in three of the five PVC-based films analysed, and a content of 500 mg kg^-1 was found in a fourth; for these determinations, extraction into acetonitrile was used. In standard tests of migration into water, 3% acetic acid and olive oil over 10 days at 40°C, migration from a given film was in all cases greatest into olive oil. Migration from the films with non-zero BPA contents ranged from 3 to 31 μg dm^-2, values higher than those reported for many other food-contact materials, but lower than the European Union specific migration limit for BPA. PVC stretch film nevertheless may make a significant contribution to contamination of foodstuffs by BPA, and should be taken into account in estimating BPA intake or exposure to this substance.     

Influence of different reactor types on Nannochloropsis oculata microalgae culture for lipids and fatty acid production

Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed-batch glass tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, yielding 3.5 × 10⁸ cells ml⁻¹, followed by fed-batch Erlenmeyer flask (1 L) at 650 μmol E m⁻² s⁻¹ with 1.7 × 10⁸ cells ml⁻¹. The highest total lipid contents (% g lipid × g dry biomass⁻¹) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m⁻² s⁻¹ and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m⁻² s⁻¹) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m⁻² s⁻¹, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n-3) and (20:4n-3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed-batch tubular reactor (7 L) at 200 μmol E m⁻² s⁻¹ contains major FAs (16:0; 38.06 ± 0.16%), (16:1n-7; 30.74 ± 0.58%), and (18:1n-9; 17.15 ± 0.91%).     

Hydrogel wound dressings based on chitosan and xyloglucan: Development and characterization

Xyloglucan is a polysaccharide isolated from chia seed gum (Salvia hispanica L.) and can act as a soluble fiber. In this investigation, several porous hydrogels were prepared from mixtures of chitosan and xyloglucan. To characterize these biomaterials, their mechanical, hydrophilic, structural, and morphological properties were measured, as well as their biodegradability and antimicrobial activity. The pore sizes of the porous hydrogels were 32.8–101.6 μm, and their water retention capacity is proportional to the added amount of xyloglucan. Dynamic degradation of the porous hydrogels with lysozymes showed progressive weight loss during the 14 days of testing. The mechanical properties improved slightly after the addition of xyloglucan. All of these results indicate that the incorporation of vegetable-derived polymers such as xyloglucan improves the properties of chitosan without affecting its antimicrobial capacity. Thus, biomaterials based on chitosan and xyloglucan are a promising option for the design of hydrogel wound dressings for medical applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47342.     

Nutritional Quality of Edible Parts of Moringa oleifera

This study was carried out in order to compare the biochemical characteristics from three edible parts of the multipurpose tree Moringa oleifera such as the leaves, flowers, and immature pods. On average, the three most abundant amino acids were glutamic acid, arginine, and aspartic acid. The fatty acids present at the highest content were linolenic acid (C18:3ω3), palmitic acid (C16:0), linoleic acid (C18:2ω6), and oleic acid (C18:1ω9). The chemical composition (of dry weight) ranged from 19.34% to 22.42% for protein, 1.28% to 4.96% for lipids, 7.62% to 14.60% for ash, and 30.97% to 46.78% for dietary fiber. M. oleifera is a nonconventional plant with substantial nutritional value.     

Adsorption of allura red dye by cross-linked chitosan from shrimp waste

The present study was designed to evaluate the chitosan, which has been obtained by deacetylation of chitin, as a biosorbent. The chitin was isolated from fermented shrimp waste by an important local industrial food biopolymer. The aim of this work was the characterization of chitosan and preparation of cross-linked chitosan- tripolyphosphate (chitosan-TPP) beads for the removal of allura red food dye from aqueous solutions. Conditions of batch adsorption such as pH, time and adsorbent dose were examined. The effectiveness of cross-linked chitosan beads for dye removal was found to be higher for pH 2 (98%, percentage of dye removal) and tends to decrease at pHs of 3 to 11 (up to 49%). The values of percentage removal show that the adsorption capacity increases with time of contact and dosage of chitosan-TPP, but red dye adsorption is mainly influenced by pH level. The cross-linked chitosan-TPP beads can significantly adsorb allura red monoazo dye from aqueous solutions even at acidic pHs unlike raw chitosan beads that tend to dissolve in acidic solutions. Consequently, this modified chitosan has characteristics that allow minimization of environmental pollution and widening the valorization of shrimp waste.     

Preparation and Characterization of Antimicrobial Films Based on Chitosan for Active Food Packaging Applications

The aim of this paper was to characterize chitosan samples from the shrimp shells for the later development of antimicrobial active systems. These systems include 100 % chitosan-based films obtained by casting, polyamide films with 5 and 10 % of chitosan obtained by extrusion and polyethylene/polyethylene terephthalate films with a coating of 0.6 % of chitosan. For that purpose, several analytical techniques including IR, ¹H NMR, GPC, and microscopic techniques (scanning electron microscopy and transmission electron microscopy) were used. Within the studied samples, C1 showed the lowest DA and MW and consequently presented the most suitable properties for the development of an active packaging. Additionally, mechanical properties were performed. The effectiveness of the developed systems was evaluated by means of microbiological assays. The tested films showed antimicrobial capacity against coliform enterobacteria, mesophilic aerobic microorganism, and yeast and moulds.     

Evaluation of Physicochemical and Antifungal Properties of Polylactic Acid–Thermoplastic Starch–Chitosan Biocomposites

Biocomposites of polylactic acid, thermoplastic starch, chitosan powder, and chitosan lyophilized powder were prepared using an extrusion process. The color, thermal, structural, mechanical, morphology, and antimicrobial properties were evaluated. The addition of thermoplastic starch and chitosan (chitosan powder and chitosan lyophilized powder) produced significant changes in color and heterogeneous surface morphology of the polylactic acid biocomposites. The thermal, mechanical, and morphometric properties of the material showed changes with the addition of thermoplastic starch and chitosan (chitosan powder and chitosan lyophilized powder). The biocomposites formulated with chitosan powder and chitosan lyophilized powder showed antifungal activity when evaluating this property. The biocomposites produced could be used in packaging applications.     

Chemical enhancers for the absorption of substances through the skin: Laurocapram and its derivatives

Absorption enhancers are substances used for temporarily increasing a membrane's permeability (e.g., the skin and mucosa), either by interacting with its components (lipids or proteins) or by increasing the membrane/vehicle partition coefficient. This article presents the results of biophysical and permeability studies performed with Laurocapram and its analogues. As shown, Laurocapram and its analogues present different enhancing efficacies, for most of both hydrophilic and lipophilic substances. The enhancing effect of Laurocapram (Azone) is attributed to different mechanisms, such as insertion of its dodecyl group into the intercellular lipidic bilayer, increase of the motion of the alkylic chains of lipids, and fluidization of the hydrophobic regions of the lamellate structure. Toxicological studies reveal a low toxicity for Laurocapram, and for some derivatives, a relationship exists between toxicity and the number of carbons in the alkylic chain. Very important, when applied to human skin, Laurocapram shows a minimal absorption, being quickly eliminated from circulation. However, although Laurocapram and its derivatives have been shown to provide enhancement, they have not been widely accepted because of their suspected pharmacological activity or questions about their safety.     

Chemical Enhancers for the Absorption of Substances Through the Skin: Laurocapram and Its Derivatives

ABSTRACT

Absorption enhancers are substances used for temporarily increasing a membrane's permeability (e.g., the skin and mucosa), either by interacting with its components (lipids or proteins) or by increasing the membrane/vehicle partition coefficient. This article presents the results of biophysical and permeability studies performed with Laurocapram and its analogues. As shown, Laurocapram and its analogues present different enhancing efficacies, for most of both hydrophilic and lipophilic substances. The enhancing effect of Laurocapram (Azone®) is attributed to different mechanisms, such as insertion of its dodecyl group into the intercellular lipidic bilayer, increase of the motion of the alkylic chains of lipids, and fluidization of the hydrophobic regions of the lamellate structure. Toxicological studies reveal a low toxicity for Laurocapram, and for some derivatives, a relationship exists between toxicity and the number of carbons in the alkylic chain. Very important, when applied to human skin, Laurocapram shows a minimal absorption, being quickly eliminated from circulation. However, although Laurocapram and its derivatives have been shown to provide enhancement, they have not been widely accepted because of their suspected pharmacological activity or questions about their safety.     

Chemical and biological characteristics of protein hydrolysates from fermented shrimp by-products

Protein hydrolysates were prepared through lactic acid fermentation of the inedible portions of shrimp (cephalothorax and exoskeleton), the by-products of shrimp processing operations. The protein-rich liquid hydrolysate was further processed into a concentrated paste via vacuum evaporation at 80 °C or was also processed into a dry powder using a spray drying method at 180 °C/140 °C (inlet/outlet temp). The laboratory compared the composition of the three forms of shrimp protein hydrolysates. The protein and ash content of the hydrolysates ranged from 8.43 ± 0.22 to 46.73 ± 1.29 and 2.03 ± 0.52 to 8.25 ± 0.14 g/100 g of wet weight. All the samples were analyzed for fifteen amino acids; the powder form was analyzed for colour, microbial content, and for heavy metal occurrence. The shrimp by-products were successfully converted into micro-nutrient by-products rich in amino acids for potential recommendations in the supplementation of animal and human diets.