Adding iron to green tea may decrease its antioxidant capacity in rats after an oral dose of the mixture

Development of Dairy Products Fortified with Plant Extracts: Antioxidant and Phenolic Content Characterization

In recent decades, there has been growing interest in the fortification of dairy products with antioxidants and phenolics derived from plant byproducts and herbs. The present study focused on the analysis of dairy products, including kefir, cream cheese, yogurt, and vegan yogurt, enhanced with aqueous extracts of plant byproducts (Citrus aurantium peel, Citrus limon peel and Rosa canina seed) and herbs (Sideritis spp., Hypericum perforatum, Origanum dictamnus, Mentha pulegium L., Melissa oficinallis, Mentha spicata L. and Lavandula angustifolia) to characterize their antioxidant content, phenolic profile, and organoleptic characteristics. Antioxidant and phenolic content were determined by Folin-Ciocalteu and ferric reducing antioxidant power (FRAP) assays and presented values up to 46.61 ± 7.22 mmol Fe²⁺/L and 82.97 ± 4.29 mg gallic acid (GAE)/g, respectively for the aqueous extracts, as well as up to 0.68 ± 0.06 mmol Fe²⁺/L and 2.82 ± 0.36 mg GAE/g for the fortified dairy products. The bioavailability of antioxidants and phenolics in fortified foods was determined after in vitro digestion and ranged between 4 and 68%. The phytochemical profile of the aqueous extracts was determined by mass spectrometry, and 162 phytochemicals were determined, from which 128 belong to the polyphenol family including flavonoids and phenolic acids. Furthermore, most of the identified compounds have been recorded to possess enhanced antioxidant capacity in correlation to the in vitro findings. Finally, organoleptic evaluation showed an overall acceptability around 3.0 ± 1.0 on a 5-point scale. In conclusion, the studied plants and herbal extracts can be used for the fortification of a variety of dairy products with potential positive effects on human health.

An Epidemiological Study Report on the Antioxidant and Phenolic Content of Selected Mediterranean Functional Foods, Their Consumption Association with the Body Mass Index, and Consumers Purchasing Behavior in a Sample of Healthy Greek Adults

Functional food consumption is shown to have a positive effect on anthropometric parameters and human health promotion. In addition, consumers seem to be more interested in food choices, that may have a positive effect on their health. The current study aimed to identify the antioxidant and phenolic content of naturally functional foods from the Mediterranean diet and to investigate consumer behavior towards their consumption in terms of their weight control, as well as their purchasing behavior and knowledge of functional foods. For this purpose, blueberries, cranberries, pomegranate, grapefruit, red peppers, almonds and mountain tea were analyzed for their phenolic content and antioxidant capacity, using the Folin-Ciocalteau and Ferric Reducing Antioxidant Power assays, respectively. Furthermore, nine hundred forty-nine healthy Greek adults participated in an epidemiological study, by completing a validated food frequency questionnaire, for the consumption of the above investigated functional foods. Five hundred and fifty participants also completed an online questionnaire investigating factors that consumers evaluate when purchasing functional foods. Study results showed that the analyzed functional foods were high in antioxidants and phenolic compounds, especially the mountain tea. The increased consumption of cranberries, pomegranate, grapefruit, red peppers and mountain tea was significantly correlated with a decreased Body Mass Index, suggesting a possible positive role, in weight control. Participants seemed to be aware of the beneficial role of these specific investigated Mediterranean functional foods to human health. They evaluated the price, taste and nutritional value, as critical factors to buy these food products. A combination of factors seems to lead them to purchase and consume these functional foods. Future epidemiological and clinical studies should be conducted in order to further evaluate consumer preferences and bioactivity mechanisms related to Mediterranean functional food consumption.

Modulation of antioxidant status in streptozotocin-induced diabetic male Wistar rats following intake of red palm oil and/or rooibos

OBJECTIVE

To investigate the role of red palm oil (RPO), rooibos tea extract (RTE) and their combined treatment (RPO + RTE) on antioxidant status in streptozotocin (STZ)-induced diabetic rats.

METHODS

Diabetes mellitus was induced by a single administration of streptozotocin (50 mg/kg) and the rats were treated for 7 weeks. Antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD)], antioxidant capacity [trolox equivalence antioxidant capacity (TEAC), oxygen radical absorbance capacity (ORAC)] as well as total protein, albumin, globulin, total glutathione, conjugated diene and thiobarbituric acid reactive substances (TBARS) were investigated.

RESULTS

Treatment with RPO, RTE and RPO + RTE significantly (p>0.05) improved liver SOD and plasma ORAC in the diabetic rats. Similarly, diabetic rats treated with RTE and RPO + RTE enhanced liver GPx. A significant (P<0.05) increase in the plasma TBARS in the diabetic control group was observed when compared with the normal control group. Treatment of diabetic rats with RTE and RPO + RTE reduced plasma TBARS to a level not significantly different at P<0.05 from the normal control group.

CONCLUSIONS

The results revealed the anti-oxidative potentials of red palm oil, rooibos and their combination in diabetic conditions and hence, they could be useful in the management of diabetes and its complications.

Determination of reactions between free radicals and selected Chilean wines and transition metals by ESR and UV-vis technique

Four different types of Chilean wines (Cabernet Sauvignon, Merlot, Carmenere and Syrah) were selected and examined in their free radical scavenging capacities by electron spin resonance (ESR) and spectrophotometric methods. The free radical scavenging properties were evaluated against 2,2-diphenyl-1-picrylhydrazyl (DPPH*) radical, 2,6-di-tert-butyl-alpha-(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadien-1-ylidene)-p-tolyloxy (Galvinoxyl) radical and hydroxyl radical (HO*). The possible effect on these scavenging properties of added transition metals to these wines was evaluated. Among the wines evaluated, Cabernet Sauvignon was the one with the highest activity against all radicals tested. The presence of added copper or iron to wines resulted in a reduced free radical scavenging capacity for all type of wines studied. The formation of redox inactive complexes between polyphenols of wine and transition metals is the possible cause of this reduction in antioxidant activity.