Research Articles (Food Science)
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Browsing Research Articles (Food Science) by Subject "Antioxidants"
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- ItemFood preservative capabilities of grape (vitis vinifera) and clementinemandarin (citrus reticulata) by-products extracts in South Africa(MDPI, 2019-03-22) Pfukwa, Trust M.; Fawole, Olaniyi A.; Manley, Marena; Gouws, Pieter A.; Opara, Umezuruike Linus; Mapiye, CletosThe drive towards sustainable food systems coupled with increased consumer sophistication have prompted innovation in waste valorization. Grape and citrus processing by-products, abundant in the Mediterranean and tropical regions, respectively, are expanding and are sustainable sources of bioactive phytochemicals that can be used as natural preservatives for foods. Phytochemical composition, antioxidant, and antimicrobial properties of extracts from grape pomace (GPE), seeds (GSE), and clementine mandarin peel and pulp (MPE) grown in South Africa were analyzed. Total phenols and carotenoids were highest in GPE followed by GSE and MPE (p ≤ 0.05). Flavonoids and anthocyanins were higher (p ≤ 0.05) in GPE and GSE compared to MPE. The GSE had the highest proanthocyanidins content followed by GPE and MPE (p ≤ 0.05). Ascorbic acid was only detected in MPE, which also had the highest titratable acidity and lowest pH values (p ≤ 0.05). The GSE had the highest antioxidant potency composite index followed by GPE and MPE (p ≤ 0.05). The order of antimicrobial activity of the extracts was MPE > GSE > GPE (p ≤ 0.05). Current findings show that GSE is a potential antioxidant while MPE holds promise as an antimicrobial for the food industry.
- ItemImpact of cold versus hot brewing on the phenolic profile and antioxidant capacity of rooibos (Aspalathus linearis) herbal tea(MDPI, 2019-10-21) Damiani, Elisabetta; Carloni, Patricia; Rocchetti, Gabriele; Senizza, Biancamaria; Tiano, Luca; Joubert, Elizabeth; de Beer, Dalene; Lucini, LuigiConsumption of rooibos (Aspalathus linearis) as herbal tea is growing in popularity worldwide and its health-promoting attributes are mainly ascribed to its phenolic composition, which may be affected by the brewing conditions used. An aspect so far overlooked is the impact of cold brewing vs regular brewing and microwave boiling on the (poly) phenolic profile and in vitro antioxidant capacity of infusions prepared from red (‘fermented’, oxidized) and green (‘unfermented’, unoxidized) rooibos, the purpose of the present study. By using an untargeted metabolomics-based approach (UHPLC-QTOF mass spectrometry), 187 phenolic compounds were putatively annotated in both rooibos types, with flavonoids, tyrosols, and phenolic acids the most represented type of phenolic classes. Multivariate statistics (OPLS-DA) highlighted the phenolic classes most affected by the brewing conditions. Similar antioxidant capacities (ORAC and ABTS assays) were observed between cold- and regular-brewed green rooibos and boiled-brewed red rooibos. However, boiling green and red rooibos delivered infusions with the highest antioxidant capacities and total polyphenol content. The polyphenol content strongly correlated with the in vitro antioxidant capacities, especially for flavonoids and phenolic acids. These results contribute to a better understanding of the impact of the preparation method on the potential health benefits of rooibos tea.
- ItemSouthern African indigenous fruits and their byproducts : prospects as food antioxidants(Elsevier, 2020) Pfukwa, Trust M.; Chikwanha, Obert C.; Katiyatiya, Chenaimoyo L. F.; Fawole, Olaniyi A.; Manley, Marena; Mapiye, CletosThe discourse regarding plant-based preservatives for food application has generally revolved around extracts from commercial fruits, vegetables, herbs and spices with indigenous fruits (IFs) on the periphery, with little investment into their valorisation. While being important food sources at community level, IFs and their byproducts are also incorporated into medicinal remedies, combating various diseases. Their ethnomedicinal usage indicates potent bioactive profile that alleviate effects of oxidative stress, which accompany disease in vivo. This is supported by in vitro antioxidant activity of the IFs and their byproducts. As such, the current review explores the potential of bioprospecting extracts from nine IFs and their byproducts as food antioxidants. Evidence presented shows that IFs have high content of bioactive compounds further translating to high antioxidant activity. Research gaps in information concerning in vitro bioactivity warrant further research to provide impetus for valorisation and food application of IFs.