Electrochemical evaluation of total antioxidant capacity of beverages using a purine-biosensor

In this paper, it was evaluated the total antioxidant capacity (TAC) of beverages using an electrochemical biosensor. The biosensor consisted on the purine base (guanine or adenine) electro-immobilization on a glassy carbon electrode surface (GCE). Purine base damage was induced by the hydroxyl radical generated by Fenton-type reaction. Five antioxidants were applied to counteract the deleterious effects of the hydroxyl radical. The antioxidants used were ascorbic acid, gallic acid, caffeic acid, coumaric acid and resveratrol. These antioxidants have the ability to scavenger the hydroxyl radical and protect the guanine and adenine immobilized on the GCE surface. The interaction carried out between the purinebase immobilized and the free radical in the absence and presence of antioxidants was evaluated by means of changes in the guanine and adenine anodic peak obtained by square wave voltammetry (SWV). The results demonstrated that the purine-biosensors are suitable for rapid assessment of TAC in beverages

Electrochemical DNA-sensor for evaluation of total antioxidant capacity of flavours and flavoured waters using superoxide radical damage

In this paper, a biosensor based on a glassy carbon electrode (GCE) was used for the evaluation of the total antioxidant capacity (TAC) of flavours and flavoured waters. This biosensor was constructed by immobilising purine bases, guanine and adenine, on a GCE. Square wave voltammetry (SWV) was selected for the development of this methodology. Damage caused by the reactive oxygen species (ROS), superoxide radical (O2·−), generated by the xanthine/xanthine oxidase (XOD) system on the DNA-biosensor was evaluated. DNA-biosensor encountered with oxidative lesion when it was in contact with the O2·−. There was less oxidative damage when reactive antioxidants were added. The antioxidants used in this work were ascorbic acid, gallic acid, caffeic acid, coumaric acid and resveratrol. These antioxidants are capable of scavenging the superoxide radical and therefore protect the purine bases immobilized on the GCE surface. The results demonstrated that the DNA-based biosensor is suitable for the rapid assess of TAC in beverages

Reuse of fruits and vegetables biowaste for sustainable development of natural ingredients

Considering the annual waste in the food sector that occurs throughout the value chain, it is important to establish strategic measures to reduce, value and reintroduce them into the industrial sector. Additionally, the constant search for the development of sustainable strategies to promote safe and healthy products for consumers has gained great prominence. Biowastes from fruits and vegetables present in their composition an excellent source of compounds of interest, which can be reused in different technological routes, providing added value in the industrial, socioeconomic and therapeutic sectors. In particular, the phenolic compounds present in fruit and vegetable biowastes, have bioactive and preservative characteristics that are excellent candidates for the development of natural ingredients that can be substitutes for synthetic preservatives. As the list of identified phenolic compounds is extensive and accessible, the interest in these compounds is gaining more and more prominence, since the use of ingredients of synthetic origin is being delayed by actions harmful to the health of the consumer. Phenolic compounds, in addition to having preservative capacity, such as antioxidant and antimicrobial capacity, are also known for their anti-inflammatory, anticancer, antidiabetic, antiallergic and other biological properties, which increases the interest in their use in functional and nutraceutical preparations. Based on this, this review gathers information on the impacts that the exacerbated generation of fruit and vegetable waste can generate in the environmental, economic and social sectors, as well as lists different ways of reusing these wastes, highlighting the characteristics of phenolic compounds.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES (PIDDAC) to CIMO (UIDB/00690/2020 and UIDP/00690/ 2020) and SusTEC (LA/P/0007/2021), national funding by F.C.T. for Tatiane C.G. Oliveira PhD grant (2021.06046.BD) and for L. Barros and E. Pereira (2021.03908.CEECIND) contracts, through the institutional scientific employment program-contract. C. Caleja are grateful to the Healthy-PETFOOD (POCI-01-0247-FEDER-047073) project for her contract. The authors are also grateful to the European Regional Development Fund (FEDER) through the Regional Operational Program North 2020, within the scope of by “BIOMA” for financial support.info:eu-repo/semantics/publishedVersio

Electroanalysis of urinary L-dopa using tyrosinase immobilized on gold nanoelectrode ensembles

The performance of an amperometric biosensor constructed by associating tyrosinase (Tyr) enzyme with the advantages of a 3D gold nanoelectrode ensemble (GNEE) is evaluated in a flow-injection analysis (FIA) system for the analysis of l-dopa. GNEEs were fabricated by electroless deposition of the metal within the pores of polycarbonate track-etched membranes. A simple solvent etching procedure based on the solubility of polycarbonate membranes is adopted for the fabrication of the 3D GNEE. Afterward, enzyme was immobilized onto preformed self-assembled monolayers of cysteamine on the 3D GNEEs (GNEE-Tyr) via cross-linking with glutaraldehyde. The experimental conditions of the FIA system, such as the detection potential (−0.200 V vs. Ag/AgCl) and flow rates (1.0 mL min−1) were optimized. Analytical responses for l-dopa were obtained in a wide concentration range between 1 × 10−8 mol L−1 and 1 × 10−2 mol L−1. The limit of quantification was found to be 1 × 10−8 mol L−1 with a resultant % RSD of 7.23% (n = 5). The limit of detection was found to be 1 × 10−9 mol L−1 (S/N = 3). The common interfering compounds, namely glucose (10 mmol L−1), ascorbic acid (10 mmol L−1), and urea (10 mmol L−1), were studied. The recovery of l-dopa (1 × 10−7 mol L−1) from spiked urine samples was found to be 96%. Therefore, the developed method is adequate to be applied in the clinical analysis

Dietary lipid level affects growth performance and nutrient utilisation of Senegalese sole (Solea senegalensis) juveniles

Over the last few years, several aspects of Senegalese sole (Solea senegalensis) culture have been developed and optimised but the dietary lipid level for optimal growth has never been determined. Hence, five isonitrogenous diets (56 % dietary protein) with increasing dietary lipid levels (4, 8, 12, 16 and 20 % DM) were fed to satiation to triplicate groups of twenty fish (mean initial weight 10 g). Fifteen tanks were randomly assigned one of the five diets. Feed was distributed using automatic feeders, and fish were fed over a 16-week period. At the end of the experiment the fish fed on diets containing the two lowest dietary lipid levels (4 and 8 %) showed a 3-fold body-weight increase with a significantly higher daily growth index than fish fed higher lipid levels (1-2 v. 0-8). Moreover, these fish displayed a significantly lower dry feed intake (12g/kg per d) and feed conversion ratio (1-0) compared with fish fed higher lipids levels (16-19 g/kg per d; feed conversion ratio 2-0). Low dietary lipid levels (< 12 %) significantly improved nutrient retention and gain and hence growth, without major effects on whole-body composition. Despite the slight alteration in n-3 PUFA muscle content in the fish fed low-fat-diets, this fish fed low dietary lipid still remains a rich n-3 PUFA product and generally maintained its nutritional value. These results evidenced a low lipid tolerance of Senegalese sole juveniles and suggest a maximal dietary inclusion level of 8 % lipids for both optimal growth and nutrient utilisation without compromising flesh quality.IDEIA; European fund FEDERinfo:eu-repo/semantics/publishedVersio

A new age for Quercus spp. fruits: review on nutritional and phytochemical composition and related biological activities of acorns

The current global food system must adapt to the expected growth of world population (about 9 billion individuals by 2050). This adaptation will probably include an increased consumption of edible wild foods, due to their richness in micronutrients and bioactive compounds, besides providing a cost-effective and sustainable way of improving caloric food security. A striking example of such natural matrices is the Quercus genus, which has the additional advantage of being widespread throughout the Northern Hemisphere. In a traditional sense, Quercus fruits (acorns) were mainly used in animal feeding, despite their potentially important role on the rural economy. But this preconception is changing. In fact, their nutritional value, high contents in phytochemical compounds, biological activity (such as antioxidant, anticarcinogenic, and cardioprotective properties) and use in the treatment of specific diseases (such as atherosclerosis, diabetes, or Alzheimer's disease) have raised the interest in integrating acorns into the human diet. Accordingly, this comprehensive overview was designed to provide an evidence-based review of the literature, with the objective to achieve useful conclusions regarding the nutritional properties, methodologies of extraction, identification, and characterization of a wide variety of bioactive compounds and scientifically validated bioactivities in Quercus species worldwide. The industrial by-products from acorn oil extraction or flour production are also included. Data regarding the analytical techniques, individual compounds, and their bioactivities, are organized in tables. The reported data are discussed and directions for further investigations are suggested, highlighting the use of acorns in food, nutraceutical, and pharmaceutical applications.info:eu-repo/semantics/publishedVersio

Contribution of different vegetable types to exogenous nitrate and nitrite exposure

This study reports the levels of nitrate and nitrite of 34 vegetable samples, including different varieties of cabbage, lettuce, spinaches, parsley and turnips, collected in several locations of an intensive agricultural area (Modivas, Vila do Conde, northern Portugal). Nitrate levels ranged between 54 and 2440 mg NO-3 kg-1, while nitrite levels ranged between 1.1 and 57 mg NO-2 kg-1. The maximum residue levels established for nitrate in spinach and lettuce samples were not exceeded. Nitrate and nitrite levels reported in the literature for the same type of samples are reviewed, as well as the contribution of vegetables to nitrate and nitrite dietary exposure of populations

Dynamics of Snoring Sounds and Its Connection with Obstructive Sleep Apnea

Snoring is extremely common in the general population and when irregular may indicate the presence of obstructive sleep apnea. We analyze the overnight sequence of wave packets --- the snore sound --- recorded during full polysomnography in patients referred to the sleep laboratory due to suspected obstructive sleep apnea. We hypothesize that irregular snore, with duration in the range between 10 and 100 seconds, correlates with respiratory obstructive events. We find that the number of irregular snores --- easily accessible, and quantified by what we call the snore time interval index (STII) --- is in good agreement with the well-known apnea-hypopnea index, which expresses the severity of obstructive sleep apnea and is extracted only from polysomnography. In addition, the Hurst analysis of the snore sound itself, which calculates the fluctuations in the signal as a function of time interval, is used to build a classifier that is able to distinguish between patients with no or mild apnea and patients with moderate or severe apnea