A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables.

It would be desirable to establish and standardize methods that can measure the total antioxidant capacity level directly from vegetable extracts containing phenolics. Antioxidant capacity assays may be broadly classified as electron transfer (ET)- and hydrogen atom transfer (HAT)-based assays. The majority of HAT assays are kinetics-based, and involve a competitive reaction scheme in which antioxidant and substrate compete for peroxyl radicals thermally generated through the decomposition of azo compounds. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes colour when reduced. ET assays include the ABTS/TEAC, CUPRAC, DPPH, Folin-Ciocalteu and FRAP methods, each using different chromogenic redox reagents with different standard potentials. This review intends to offer a critical evaluation of existing antioxidant assays applied to phenolics, and reports the development by our research group of a simple and low-cost antioxidant capacity assay for dietary polyphenols, vitamins C and E, and human serum antioxidants, utilizing the copper(II)-neocuproine reagent as the chromogenic oxidizing agent, which we haved named the CUPRAC (cupric ion reducing antioxidant capacity) method. This method offers distinct advantages over other ET-based assays, namely the selection of working pH at physiological pH (as opposed to the Folin and FRAP methods, which work at alkaline and acidic pHs, respectively), applicability to both hydrophilic and lipophilic antioxidants (unlike Folin and DPPH), completion of the redox reactions for most common flavonoids (unlike FRAP), selective oxidation of antioxidant compounds without affecting sugars and citric acid commonly contained in foodstuffs and the capability to assay -SH bearing antioxidants (unlike FRAP). Other similar ET-based antioxidant assays that we have developed or modified for phenolics are the Fe(III)- and Ce(IV)-reducing capacity methods.

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Comparative Evaluation of Various Total Antioxidant Capacity Assays Applied to Phenolic Compounds with the CUPRAC Assay

There is an increased interest in the role that some nutrients may play in preventing or ameliorating the effect of major diseases (for example, some types of cancer, cardiovascular diseases, eye disorders, among others). In this respect, the bioavailability or the proportion of an ingested nutrient that is made available (that is, delivered to the bloodstream) for its intended mode of action is more relevant than the total amount present in the original food. Disruption of the natural matrix or the microstructure created during processing may influence the release, transformation, and subsequent absorption of some nutrients in the digestive tract. Alternatively, extracts of bioactive molecules (for example, nutraceuticals) and beneficial microorganisms may be protected during their transit in the digestive system to the absorption sites by encapsulation in designed matrices. This review summarizes relevant in vivo and in vitro methods used to assess the bioavailability of some nutrients (mostly phytochemicals), types of microstructural changes imparted by processing and during food ingestion that are relevant in matrix-nutrient interactions, and their effect on the bioavailability of selected nutrients.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1750-3841.2007.00274.x

Food microstructure affects the bioavailability of several nutrients.

http://ssu.ac.ir/cms/fileadmin/user_upload/Mtahghighat/tfood/ARTICLES/koliat/Natural_products_as_antimicrobial_agents.pdf

Natural products as antimicrobial agents

https://boa.unimib.it/retrieve/handle/10281/70698/104922/1-s2.0-S0959652613007440-main.pdf

Current options for the valorization of food manufacturing waste: a review

Phenolic compounds in plants and agri-industrial by-products: Antioxidant activity, occurrence, and potential uses

Phenolic compounds have been shown to exhibit bioactive properties, and in particular antioxidant effects A phenolic-rich fraction has been isolated from the aqueous by-product obtained during the milling of oil palm fruits The objectives of the study were to determine the phenolic content of the crude and ethanolic extracts of oil palm fruits and to evaluate the antioxidant properties of these extracts The total phenolics content of the crude and ethanol extracts as determined by the Folin-Ciocalteu method were found to be 403 +/- 05 and 496 +/- 06 mg GAE/g extract (dry basis), respectively The radical scavenging activity of the extracts determined using 2,2 diphenyl-1-picrylhydrazyl radical (DPPH) indicated that both crude and ethanol extracts exhibit hydrogen-donating capacity, and have antiradical power (ARP) comparable to ascorbic acid The DPPH radical scavenging activity of the extracts were less than that of gallic acid, but the time-course variations of the scavenging curves suggest that the extracts acted by a mechanism similar to that of gallic acid The electron-donating potentials of the extracts were inferred from the hydrogen peroxide scavenging and reducing power assays The reducing power of crude and ethanol extracts at 1 mM GAE were found to be comparable to that of 03 mM gallic acid The extracts indicated complete scavenging of hydrogen peroxide at concentrations above 04 mM GAE These findings suggest that the crude and ethanol extracts are able to scavenge free radicals, by either hydrogen or electron donating mechanisms, and can therefore act as primary antioxidants

/pdf/antioxidant-properties-of-palm-fruit-extracts-37vng3rceq.pdf

Antioxidant properties of palm fruit extracts.

Oil palm phenolics and vitamin E reduce atherosclerosis in rabbits

The invention provides a composition for the prevention and inhibition of oxidative stress and hemolysis in human red blood cell wherein said composition compounds obtained from the aqueous stream of palm oil milling (palm oil vegetation liquor), in particular from vegetative liquor from the milling of palm oil fruit.

Botanical extract from the aqueous stream of the palm oil milling process for the prevention and inhibition of oxidative stress and haemolysis in human red blood cells

Nagendran Balasundram

Papers

Phenolic compounds in plants and agri-industrial by-products: Antioxidant activity, occurrence, and potential uses

Antioxidant properties of palm fruit extracts.

Oil palm phenolics and vitamin E reduce atherosclerosis in rabbits

Botanical extract from the aqueous stream of the palm oil milling process for the prevention and inhibition of oxidative stress and haemolysis in human red blood cells