Factors affecting the oxidative activity of laccase towards biphenyl derivatives in homogeneous aqueous-organic systems

Catalytic oxidation of biphenyl derivatives was investigated using laccase in a homogeneous aqueous-organic system. A thermostable laccase from Trametes sp. showed the highest catalytic activity for the oxidation of 4-hydroxybiphenyl (4-HB) at a reaction temperature of 60 degrees C when dimethylsulfoxide (DMSO) was employed as a co-solvent. Furthermore, the catalytic performance was successfully enhanced by the incorporation of a laccase mediator system (LMS) into the aqueous-DMSO media. The catalytic performance strongly depended on the type of mediator, and the highest activity was observed with 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as mediator, suggesting the importance of the selection of a suitable mediator. It was verified that this mediator system is applicable to the oxidation of several biphenyl derivatives with hydroxyl groups.     

Enhanced selenium content in buckwheat (<Emphasis Type="Italic">Fagopyrum esculentum</Emphasis> Moench) and pumpkin (<Emphasis Type="Italic">Cucurbita pepo</Emphasis> L.) seeds by foliar fertilisation

The fruit and thin-husked seeds of the pumpkin (Cucurbita pepo L.) and buckwheat grain (Fagopyrum esculentum Moench), both grown in Slovenia, were analysed for selenium (Se) content following foliar application of Se(VI) solution during the period of blooming. Samples were digested by a H₂SO₄-HNO₃-H₂O₂-V₂O₅ mixture and Se determined, based on hydride generation atomic fluorescence spectrometry. The whole procedure from weighing to measuring was carried out in the same Teflon vessel. The detection limit of the method was 0.14 ng g^–1 solution. Buckwheat seeds from untreated plants contained 47 ng g^–1 of Se and 394 ng g^–1 from plants after foliar fertilisation with Se. Pumpkin seeds from untreated plants contained 108 ng g^–1 of Se, and 381 ng g^–1 of Se from Se-treated plants, all per lyophilised sample. Se content in lyophilised pumpkin fruit was 15 ng g^–1 in untreated plants and 20 ng g^–1 in Se-treated pumpkin plants. It is thus feasible to enhance Se content in buckwheat and pumpkin seeds by foliar fertilisation, making them a rich source of dietary Se and useful as a raw material for enriched food products.     

Effect of steaming,freezing, and re-steaming on the texture properties of non-glutinous rice cakes

The effects of steaming time (6, 8, and 10 min), freezing storage period, and re-steaming for thawing on the textural properties of non-glutinous rice cakes (baekseolgi) were investigated. As the steaming time increased, the rice cakes softened. In particular, the sample that was steamed for 10 min showed lower hardness than those steamed for shorter periods. A short period of steaming was insufficient for water bound to the surface of the starch granules to penetrate the granules in the dough. During the re-steaming process of the frozen non-glutinous rice cake samples, the retrogradation of starch and water syneresis contributed to the increased hardness of non-glutinous rice cakes.     

Development of a long‐life vacuum‐packaged ready‐to‐eat meat product based on a traditional Portuguese seasoned meat

Carne do alguidar is a Portuguese traditional pork fried meat, usually manufactured for self‐consumption purposes. This study developed a ready‐to‐eat (RTE) meat product, to meet today's consumers’ convenience, manufactured at the industrial scale evaluating its quality and shelf life, assessing the effect of vacuum packaging and the use of an antioxidant (50 ppm BHT) to enhance oxidative stability. Physicochemical and microbiological parameters were assessed, and a sensory analysis was performed. Interestingly, no significant differences were recorded between control (non‐BHT) and antioxidant (BHT) samples. Microbiological counts remained at low levels throughout the storage period, ensuring the product's required microbiological quality. At later storage stages, higher values of thiobarbituric acid‐reactive substances arose and off flavours and aromas were perceived. Still, overall appreciation was not affected until 12 months of storage and a significant depreciation was perceived only after 15 months. Fibrousness and rising of off flavours were negatively correlated with overall appreciation.     

Dietary intakes of six intense sweeteners by Irish adults

This research investigated the intakes of six intense sweeteners: acesulfame-K (E950), aspartame (E951), cyclamate (E952), saccharin (E954), sucralose (E955), and steviol glycosides (E960) in the diets of Irish adults, using data from the National Adult Nutrition Survey. A food label survey that included products currently available on the Irish market supplemented the analysis. Sweetener intakes were investigated using three different exposure scenarios; beginning with a crude assessment which assumed that all foods permitted to contain the additives of interest always did contain them, and at their maximum permitted level (Tier 1). Refined assessments estimated intakes of the six sweeteners using food consumption data up to brand level with additive occurrence data from a survey of products currently available on the Irish market (Tier 2) and sweetener concentration data (Tier 3). Results of all exposure assessment scenarios demonstrate that intakes of each of the sweeteners of interest by the total population were below the relevant ADI level (mg kg^?1 bodyweight^?1), even by high consumers (P99). The three sweeteners consumed in highest amounts were acesulfame-k, aspartame, and sucralose. The main sources of these sweeteners in the diet were ‘cider and perry’, ‘energy reduced and no added sugar (ER and NAS) carbonated flavoured drinks’, ‘table-top sweeteners’, ‘dairy products’, ‘solid food supplements’, and ‘sauces’. Intakes of the six intense sweeteners are currently not a concern among Irish adults. However, exposure to these chemicals should be monitored on a regular basis due to evolving market and consumption patterns.     

Development and validation of an HPLC method with fluorescence detection for the determination of fluorescent whitening agents migrating from plastic beverage cups

An HPLC method with fluorescence detection has been developed and validated for the quantification of six fluorescent whitening agents (FWA) in plastic beverage cups after extraction and in food simulants after migration at 70°C for 2 h. The sensitivity of the method was high with LODs ranging from 0.053 to 0.251 μg kg^?1 and LOQs from 0.107 to 0.504 μg kg^?1. Accuracy and precision were highly acceptable, with recoveries greater than 82% and RSDs (%) below 16%. The expanded combined uncertainty was found to be less than 23% for the measurements of all studied FWAs. In extracting the analytes from food contact materials (FCM), accelerated solvent extraction (ASE) and Soxhlet extraction were applied using ethanol as the extraction solvent. The results obtained for FWA in 10 different food plastic cups, made from different polymers, were compared. The ASE technique proved to be faster, more effective and efficient than Soxhlet extraction. Migration tests with official food simulants from Regulation (EU) No 10/2011 showed that the substances studied could potentially migrate using the selected migration conditions. The most pronounced effect was observed in case of simulant D1 (50% w/v ethanol in water). The analytical method proved to be a simple, fast, sensitive and reliable tool for the simultaneous quantification of six of the most used FWAs in both FCM extracts and food simulants after migration experiments.     

Resveratrol analogue,HS-1793, inhibits inflammatory mediator release from macrophages by interfering with the TLR4 mediated NF-κB activation

Food Science and Biotechnology - Resveratrol is known to have anti-inflammatory properties. However, high-dose resveratrol is required for optimal anti-inflammatory effects. HS-1793 is a derivative...