Re-evaluation of shellac (E 904) as a food additive and a new application on the extension of use of shellac (E 904) in dietary foods for special medical purposes.

The present opinion deals with the re-evaluation of shellac (E 904) when used as a food additive and with the new application on the extension of use of shellac (E 904) in dietary foods for special medical purposes. The Panel derived an acceptable daily intake (ADI) of 4 mg/kg body weight (bw) per day for wax-free shellac (E 904) produced by physical decolouring, based on a NOAEL of 400 mg/kg bw per day and applying an uncertainty factor of 100. The Panel concluded that the ADI of 4 mg/kg bw per day should be considered temporary for wax-free shellac (E 904) produced by chemical bleaching, while new data are generated on the identity and levels of the organochlorine impurities in E 904. This ADI is not applicable for wax-containing shellac as a food additive. For several age groups, the ADI was exceeded at the 95th percentile in the non-brand-loyal exposure assessment scenario and maximum level exposure assessment scenario. Considering the low exceedance and the fact that both the exposure estimation and the toxicological evaluation of shellac were conservative, the panel concluded that the calculated exceedance of the ADI does not indicate a safety concern. The Panel recommended to the European Commission separating specifications for E 904 depending on the manufacturing process, chemical bleaching and physical decolouring, because they result in different impurities; revising the definition of the food additive to include a description of each manufacturing process; deleting information on wax-containing shellac from the EU specifications; revising the acid value for wax-free shellac produced by chemical bleaching; lowering the maximum limit for lead; to consider introducing limits for other toxic elements potentially present in shellac; including a maximum limit for chloroform and total inorganic chloride in the EU specification for shellac produced by chemical bleaching.

Influence of Cotton Pre-Treatment on Dyeing with Onion and Pomegranate Peel Extracts.

In this paper the possibility of applying natural dyes on cellulose fibres were researched with respect to the impact of cotton material pre-treatment (scouring, chemical bleaching, mercerization and mordanting), using renewable sources of natural dyes (waste as a source). As mordants, metal salts of copper, aluminium and ferrum were used, and the influence on colour change as well as on fastness properties were analysed. The natural dyes were extracted from onion peel (Allium cepa L.) and pomegranate peel (Punica granatum L.). In spectrophotometric analysis performed of the plant extracts, the onion extract has peaks at 400 and 500 nm, resulting in red-orange colourations and the pomegranate extract shows a maximum at 400 nm, i.e., in the yellow region, which is characteristic of punicalin. Results show significant influence of cotton pre-treatments on colour appearance and fastness properties, caused by pre-treatments affecting the properties and structure of the cotton itself. The positive effect of mercerization on dye absorption and bonding is confirmed. For wash and light fastness properties, more satisfactory results have been obtained for yarns dyed with pomegranate peel natural dye, and the key importance of mordants for fastness properties has been confirmed.

Chemical and biochemical bleaching of oat hulls: The effect of hydrogen peroxide, laccase, xylanase and sonication on optical properties and chemical composition.

Oat hulls are an excellent dietary fibre source for food supplements due to their rich lignocellulose composition as well as their great abundance as low-value agricultural side stream. For the production of white fibre supplements, a mild, but effective bleaching of the hulls is required. Chemical bleaching with hydrogen peroxide and sodium hydroxide was here found to be a suitable method increasing the CIE L* value (corresponds to a lightness value) above 85. The developed method is mild, retaining the hull's chemical composition. Only a minor decrease in coniferaldehyde structures upon bleaching was detected. Colour and chemical variabilities of oat hulls from different growth seasons did not influence the required bleaching conditions to achieve the desired optical properties. The inclusion of biochemical bleaching steps utilizing the xylanase Pentopan Mono BG, the laccase NS51003 and sonication was industrially not feasible as they could not reduce the required amount of subsequently applied bleaching chemicals significantly.

Chemical Bleaching to Minimize Fluorescence Interference in Raman Spectroscopic Measurements for Sulfonated Polystyrene Solutions.

Auto-fluorescence is a significant challenge for Raman spectroscopic analyses. Since fluorescence is a much stronger phenomenon than Raman scattering, even trace fluorescent impurities can overwhelm the Raman signal. Strategies to minimize fluorescence interference in Raman measurements include either an instrumental-based approach or treatment of the sample itself to minimize fluorescence. Efforts focused on sample-based treatments to reduce fluorescence interferences have generally focused on sample purification and photobleaching methodologies. In this work, we present a sample treatment approach based upon chemical bleaching to remove fluorescence from Raman measurements of aqueous solutions of sulfonated polystyrene (SPS). Synthetic batches of SPS are characterized by a wide variation in fluorescence from minimum to a catastrophic level, which greatly limits the use of Raman spectroscopy. We systematically investigate the efficacy of various sample-based treatments of the SPS samples. An important acceptance criterion is that the procedure effectively and reliably removes fluorescence without damaging the SPS component. The chemical bleaching, which involves the addition of hydrogen peroxide and incubation at 60 ℃, is found to be highly effective. The parameters affecting the bleaching efficacy are studied, including temperature, hydrogen peroxide dosage, and bleaching time. Classification models are then developed based on the drastically diverse fluorescence background levels in Raman spectra of SPS to help optimize bleaching time for each specific sample. This work serves as an example of using chemical bleaching to remove fluorescence, which is inexpensive and readily available. It can facilitate a broader use of Raman spectroscopy as a quantitative qualitative control method in industrial settings.

Optimization of Sample Preparation processes of Bone Material for Raman Spectroscopy.

Raman spectroscopy has recently been investigated for use in the calculation of postmortem interval from skeletal material. The fluorescence generated by samples, which affects the interpretation of Raman data, is a major limitation. This study compares the effectiveness of two sample preparation techniques, chemical bleaching and scraping, in the reduction of fluorescence from bone samples during testing with Raman spectroscopy. Visual assessment of Raman spectra obtained at 1064 nm excitation following the preparation protocols indicates an overall reduction in fluorescence. Results demonstrate that scraping is more effective at resolving fluorescence than chemical bleaching. The scraping of skeletonized remains prior to Raman analysis is a less destructive method and allows for the preservation of a bone sample in a state closest to its original form, which is beneficial in forensic investigations. It is recommended that bone scraping supersedes chemical bleaching as the preferred method for sample preparation prior to Raman spectroscopy.

Multiple effects of swelling by sodium bicarbonate after delignification on enzymatic saccharification of rice straw.

The multiple effects of pretreatments by chemical delignification using acidified sodium chlorite (ASC) and swelling using sodium bicarbonate (SB) for enzymatic saccharification of rice straw in bioethanol production have been investigated in this study. The treatment with the combination of ASC three times (3× ASC) first and SB later resulted in the significant reduction in Klason lignin content up to 90% (wt./wt.). By the saccharification of the pretreated rice straw with cellulase enzymes, it was confirmed that SB treatment was an important step in the pretreatment process not only to disintegrate the cellulose structure but also to facilitate the amorphization of the crystalline cellulose as well as the extended removal of integrated lignin. Furthermore, FTIR analyses revealed that the crystal type of cellulose appeared to be changed from type I to type II by SB treatment, thereby increasing the cellulose surface area and making it more accessible to the cellulase enzyme. Conversion rate to sugar was remarkably increased when 3× ASC + SB treatments were applied to untreated rice straw, even though the saccharification of the treated rice straw was performed at a low enzyme loading (1/100, wt.-enzymes/wt.-substrate). Conclusively, rice straw could be saccharified at high yield in short time at low cellulase loading, enables the enzymatic saccharification to be more feasible for practical bioethanol production using rice straw as a substrate.