Process Development for the Detoxification of Fermentation Inhibitors from Acid Pretreated Microalgae Hydrolysate

The aim of this study was to remove 5-hydroxymethyl furfural (5-HMF) and furfural, known as fermentation inhibitors, in acid pretreated hydrolysates (APH) obtained from Scenedesmus obliquus using activated carbon. Microwave-assisted pretreatment was used to produce APH containing glucose, xylose, and fermentation inhibitors (5-HMF, furfural). The response surface methodology was applied to optimize key detoxification variables such as temperature (16.5–58.5 °C), time (0.5–5.5 h), and solid–liquid (S-L) ratio of activated carbon (0.6–7.4 w/v%). Three variables showed significant effects on the removal of fermentation inhibitors. The optimum detoxification conditions with the maximum removal of fermentation inhibitors and the minimum loss of sugars (glucose and xylose) were as follows: temperature of 36.6 °C, extraction time of 3.86 h, and S-L ratio of 3.3 w/v%. Under these conditions, removal of 5-HMF, furfural, and sugars were 71.6, 83.1, and 2.44%, respectively, which agreed closely with the predicted values. When the APH and detoxified APH were used for ethanol fermentation by S. cerevisiae, the ethanol produced was 38.5% and 84.5% of the theoretical yields, respectively, which confirmed that detoxification using activated carbon was effective in removing fermentation inhibitors and increasing fermentation yield without significant removal of fermentable sugars.     

Development of Ultrasound-Assisted Extraction to Produce Skin-Whitening and Anti-Wrinkle Substances from Safflower Seed

In this study, ultrasound-assisted extraction (UAE) was applied to extract bioactive substances with skin-whitening, anti-wrinkle, and antioxidant effects from safflower seeds, and the extraction conditions were optimized by a central composite design. The independent variables, including extraction time (5.0~55.0 min), extraction temperature (26.0~94.0 °C), and ethanol concentration (0.0~100%), were optimized to increase tyrosinase activity inhibitory (TAI), collagenase activity inhibitory (CAI), and radical scavenging activity (RSA), which are indicators of skin-whitening, anti-wrinkle, and antioxidant effects. An extraction time of 26.4 min, extraction temperature of 52.1 °C, and ethanol concentration of 50.7% were found to be optimum conditions of UAE, under which TAI, CAI, and RSA were 53.3%, 91.5%, and 27.7%, respectively. The extract produced by UAE was analyzed by LC-MS/MS, and maleic acid and levulinic acid were identified as the main substances. Therefore, UAE is evaluated as an effective process to extract skin-whitening, anti-wrinkle, and antioxidant substances from safflower seeds at lower temperatures and shorter extraction times compared to the conventional extraction methods. Overall, safflower seeds extract can be used as a material for value-added cosmetics, including maleic acid and levulinic acid, which have bioactive functions.     

Multisyringe Flow Injection Analysis of Tropomyosin Allergens in Shellfish Samples

This paper presents the development and the application of a multisyringe flow injection analysis system for the fluorimetric determination of the major heat-stable known allergen in shrimp, rPen a 1 (tropomyosin). This muscle protein, made up of 284 amino acids, is the main allergen in crustaceans and can be hydrolyzed by microwave in hydrochloric acid medium to produce glutamic acid, the major amino acid in the protein. Glutamic acid can then be quantified specifically by thermal conversion into pyroglutamic acid followed by chemical derivatization of the pyroglutamic acid formed by an analytical protocol based on an OPA-NAC reagent. Pyroglutamic acid can thus be quantified between 1 and 100 µM in less than 15 min with a detection limit of 1.3 µM. The method has been validated by measurements on real samples demonstrating that the response increases with the increase in the tropomyosin content or with the increase in the mass of the shrimp sample.     

The equilibrium characteristics of pyridoxine hydrochloride sorption on clinoptilolite

Pyridoxine hydrochloride (vitamin B₆) sorption by clinoptilolite from aqueous solutions has been studied at 283, 295, and 317 K. Enhancement of the sorption with decreasing temperature has been found. Isotherm of pyridoxine hydrochloride adsorption from dilute solutions may be described by the Langmuir theory. It has been shown that the monolayer coverage of clinoptilolite surface with pyridoxine occurs via the equivalent exchange with extra-framework cations of the sorbent. Thermodynamic parameters of vitamin monolayer adsorption have been determined. It has been concluded that the polymolecular adsorption is due to the formation of pyridoxine associates in the sorbent mesopores.     

Multiresidue determination of pesticides in fruit and vegetables by gas chromatography/tandem mass spectrometry

Pesticide residues in fruit and vegetables were determined by gas chromatography/tandem mass spectrometry (GC/MS/MS). Electron impact (EI)/MS/MS and chemical ionization (CI)/MS/MS were developed for 80 compounds, including organochlorine, organophosphorus, organonitrogen, and pyrethroids, providing unambiguous spectral confirmation for these complex matrixes. Residues were extracted from samples with acetone followed by a mixture of dichloromethane-petroleum ether. Two injections per sample were required for analysis of the entire pesticide list by EI/MS/MS and CI/MS/MS. Initial steps involving cleanup and concentration of extracts were eliminated. The excellent selectivity and good linearity allowed quantification and identification of low levels of pesticides in the most difficult matrixes. The method has been used for routine analysis of many vegetables.     

Effects of Sargassum thunbergii Extract on Skin Whitening and Anti-Wrinkling through Inhibition of TRP-1 and MMPs

Sargassum thunbergii has been traditionally used as an edible and medicinal material in oriental countries. However, the skin-whitening and anti-wrinkling effects of S. thunbergii have not yet been investigated. This study was conducted to establish optimal extraction conditions for the production of bioactive compounds with antioxidant activity as well as skin-whitening and anti-wrinkle effects using ultrasound-assisted extraction (UAE) in S. thunbergii. The extraction time (5.30~18.7 min), extraction temperature (22.4~79.6 °C), and ethanol concentration (0.0~99.5%), which are the main variables of the UAE, were optimized using a central composite design. Quadratic regression equations were derived based on experimental data and showed a high coefficient of determination (R² > 0.85), demonstrating suitability for prediction. The optimal UAE condition for maximizing all dependent variables, including radical scavenging activity (RSA), tyrosinase inhibitory activity (TIA), and collagenase inhibitory activity (CIA), was identified as an extraction time of 12.0 min, an extraction temperature of 65.2 °C, and ethanol of 53.5%. Under these conditions, the RSA, TIA, and CIA of S. thunbergii extract were 86.5%, 88.3%, and 91.4%, respectively. We also confirmed S. thunbergii extract had inhibitory effects on the mRNA expression of tyrosinase-related protein-1, matrix metalloproteinase-1, and matrix metalloproteinase-9, which are the main genes of melanin synthesis and collagen hydrolysis. Liquid chromatography-tandem mass spectrometry was used to identify the main phenolic compounds in S. thunbergii extract, and caffeic acid was identified as a major peak, demonstrating that high value-added ingredients with skin-whitening and anti-wrinkling effects can be produced from S. thunbergii and used for developing cosmetic materials.     

Determination of carbaryl, carbofuran and methiocarb in cucumbers and strawberries by monoclonal enzyme immunoassays and high-performance liquid chromatography with fluorescence detection. An analytical comparison

Carbaryl, carbofuran and methiocarb are three of the most important N-methylcarbamate pesticides. In the present work, the application of laboratory-developed monoclonal antibody-based enzyme-linked immunosorbent assays (ELISAs) to the determination of these compounds in fruits and vegetables is described. Cucumbers and strawberries were spiked with the three carbamates at 10, 50 and 200 ppb. After extraction and clean-up, samples were analyzed by immunoassay and by HPLC with post-column derivatization and fluorescence detection (US Environmental Protection Agency Method 531.1). Results obtained by ELISA correlated well with those obtained by HPLC, both in terms of accuracy and precision. Recoveries were in the 60-90% range by ELISA and in the 50-90% range by HPLC, depending on the particular combination of commodity, pesticide, and fortification level under consideration. ELISAs were also applied to the analysis of non-purified sample extracts with excellent results: recoveries close to 100% were obtained, while maintaining similar precision values. This approach avoids the use of solid-phase extraction columns, saves time, and considerably increases the sample throughput. Results clearly indicate that the developed immunoassays may be suitable for the quantitative and reliable determination of carbaryl, carbofuran and methiocarb in fruits and vegetables even without including clean-up steps. These considerations make these ELISAs very useful analytical tools for monitoring and regulatory programs, without the need of complex and expensive instrumentation.     

Structural transformation with "negative volume expansion": chemical bonding and physical behavior of TiGePt

The synthesis and a joint experimental and theoretical study of the crystal structure and physical properties of the new ternary intermetallic compound TiGePt are presented. Upon heating, TiGePt exhibits an unusual structural phase transition with a huge volume contraction of about 10?%. The transformation is characterized by a strong change in the physical properties, in particular, by an insulator-metal transition. At temperatures below 885?°C TiGePt crystallizes in the cubic MgAgAs (half-Heusler) type (LT phase, space group F43m, a = 5.9349(2)??). At elevated temperatures, the crystal structure of TiGePt transforms into the TiNiSi structure type (HT phase, space group Pnma, a = 6.38134(9)??, b = 3.89081(5)??, c = 7.5034(1)??). The reversible, temperature-dependent structural transition was investigated by in-situ neutron powder diffraction and dilatometry measurements. The insulator-metal transition, indicated by resistivity measurements, is in accord with band structure calculations yielding a gap of about 0.9?eV for the LT phase and a metallic HT phase. Detailed analysis of the chemical bonding in both modifications revealed an essential change of the Ti-Pt and Ti-Ge interactions as the origin of the dramatic changes in the physical properties.