Bioactive compounds and enzymatic browning inhibition in cloudy apple juice by a new magnetic UVM-7-SH mesoporous material.

Fruits and vegetables juices present a high supply of polyphenols, making them highly exposed to enzymatic browning. In this work, we report a novel magnetized mesoporous silica material (Fe3O4NPs-UVM-7) functionalised with thiol and amine groups and evaluate their effect on the enzymatic browning as well as the physicochemical properties (pH and °Brix), bioactive compounds (ascorbic acid, total phenolics, flavonoids, and flavonols) and the antioxidant capacity of cloudy apple juice. From the obtained results, the mesoporous silica material magnetized by 11 % (w/w) with magnetite and functionalized with thiol groups reduce by 70 % the enzymatic browning in apple juice. It did not affect the physicochemical parameters such as pH or total soluble solids with respect to freshly squeezed juice. In addition, the content of flavonoids, vitamin C, and the antioxidant capacity measured by ABTS are also not affected by oxidation. However, the total content of polyphenols in the treated juice drops by 15 % compared to freshly squeezed juice, nonetheless, the loss is 20 % less than the control untreated. Thus, the material mitigates the loss of total polyphenols and also the antioxidant capacity.

Probability of high-risk genetic matching with oocyte and semen donors: complete gene analysis or genotyping test?

PURPOSE: To estimate the probability of high-risk genetic matching when assisted reproductive techniques (ART) are applied with double gamete donation, following an NGS carrier test based on a complete study of the genes concerned. We then determine the results that would have been obtained if the genotyping tests most widely used in Spanish gamete banks had been applied. METHODS: In this descriptive observational study, 1818 gamete donors were characterised by NGS. The pathogenic variants detected were analysed to estimate the probability of high-risk genetic matching and to determine the results that would have been obtained if the three most commonly used genotyping tests in ART had been applied. RESULTS: The probability of high-risk genetic matching with gamete donation, screened by NGS and complete gene analysis, was 5.5%, versus the 0.6-2.7% that would have been obtained with the genotyping test. A total of 1741 variants were detected, including 607 different variants, of which only 22.6% would have been detected by all three genotyping tests considered and 44.7% of which would not have been detected by any of these tests. CONCLUSION: Our study highlights the considerable heterogeneity of the genotyping tests, which present significant differences in their ability to detect pathogenic variants. The complete study of the genes by NGS considerably reduces reproductive risks when genetic matching is performed with gamete donors. Accordingly, we recommend that carrier screening in gamete donors be carried out using NGS and a complete study with nontargeted analysis of the variants of the screened genes.

Inhibitory Effect of Azamacrocyclic Ligands on Polyphenol Oxidase in Model and Food Systems.

Enzymatic browning is one of the main problems faced by the food industry due to the enzyme polyphenol oxidase (PPO) provoking an undesirable color change in the presence of oxygen. Here, we report the evaluation of 10 different azamacrocyclic compounds with diverse morphologies as potential inhibitors against the activity of PPO, both in model and real systems. An initial screening of 10 ligands shows that all azamacrocyclic compounds inhibit to some extent the enzymatic browning, but the molecular structure plays a crucial role on the power of inhibition. Kinetic studies of the most active ligand (L2) reveal a S-parabolic I-parabolic noncompetitive inhibition mechanism and a remarkable inhibition at micromolar concentration (IC50 = 10 µM). Furthermore, L2 action has been proven on apple juice to significantly reduce the enzymatic browning.

Influence of the functionalisation of mesoporous silica material UVM-7 on polyphenol oxidase enzyme capture and enzymatic browning.

Polyphenol oxidase (PPO), also known as tyrosinase and catechol oxidase, is the enzyme responsible for enzymatic browning in foods. It causes undesirable organoleptic, nutritional and colour changes. Here, we report the preparation of five nanomaterials and a study of their ability to modulate PPO enzyme activity. The materials consist of UVM-7 supports (a mesoporous silica material) modified with diverse functional groups (i.e. amine, carboxylic acid, isocyanate, alkane and pyridine). We also studied the PPO immobilisation capability of the materials. All the materials, except the carboxylic acid functionalised one, offer high PPO loading capabilities and the immobilisation speed increases with functionalisation. Nevertheless, only a minor effect of the inhibition of enzymatic browning was produced. Furthermore, the amine containing material was able to capture not only PPO, but also the oxidation products. Such behaviour was validated with fresh apple juice in which browning was avoided, even 90 min in the presence of oxygen at room temperature.

Full inhibition of enzymatic browning in the presence of thiol-functionalised silica nanomaterial.

Darkening processed fruits and vegetables is caused mainly by enzymatic browning through polyphenol oxidase (PPO) action. Accordingly, we explored the potential of four silica-based materials (MCM-41 nanometric size, MCM-41 micrometric size, UVM-7 and aerosil), non-functionalised and functionalised with thiol groups, to inhibit PPO activity in the model system and apple juice. All materials showed relevant performance when immobilising and inhibiting PPO in model systems, and support topology is a main factor for enzyme immobilisation and inhibition. Thiol-containing silica UVM7-SH showed the greatest inactivation, and similar browning values to those obtained by acidification. The enzyme's kinetic parameters in the presence of UVM-7-SH suggested non-competitive inhibition, which indicated that the material interacted with the enzyme, but beyond the active centre. In real systems, UVM-7-SH completely inhibited enzymatic browning in apple juice (cv. Granny Smith and cv. Golden Delicious) up to 9days after 5min of contact.

Seroprevalence of antibodies against Salmonella enterica subsp. enterica serovar gallinarum-pullorum in wild doves (Zenaida asiatica and Zenaida macroura) from the northeast of Mexico.

A cross-sectional survey was conducted in order to determine the seroprevalence and to identify some factors associated with the presence of antibodies against Salmonella enterica subsp. enterica serovar Gallinarum-Pullorum in white-winged (Zenaida asiatica) and mourning doves (Zenaida macroura) from hunting areas of Northeast Mexico. From September to October 2006, 201 serum samples were analyzed with the seroagglutination test. The overall seroprevalence of S. enterica subsp. enterica serovar Gallinarum-Pullorum was 26.3%, and was similar for white-winged doves (26.4%) and mourning doves (26.1%), but higher for juveniles (30.8%) and females (34.6%). Seroprevalence was associated with the weight of the doves (prevalence ratio [PR]=1.52, P<0.0001) and the municipality where the doves were hunted (PR=1.31, P<0.0001). This survey study emphasizes the need to conduct similar studies on wild birds to determine the risk of S. enterica subsp. enterica serovar Gallinarum-Pullorum to commercial flocks. In addition, to the best of our knowledge this is the first report of the serological evidence suggesting infection with S. enterica subsp. enterica serovar Gallinarum-Pullorum in wild white-winged and mourning doves.