Are the major antioxidants derived from soy protein and fructo-oligosaccharides model systems colored aqueous soluble or insoluble compounds?

Adaptation and Validation of QUick, Easy, New, CHEap, and Reproducible (QUENCHER) Antioxidant Capacity Assays in Model Products Obtained from Residual Wine Pomace

Evaluation of the total antioxidant capacity of solid matrices without extraction steps is a very interesting alternative for food researchers and also for food industries. These methodologies have been denominated QUENCHER from QUick, Easy, New, CHEap, and Reproducible assays. To demonstrate and highlight the validity of QUENCHER (Q) methods, values of Q-method validation were showed for the first time, and they were tested with products of well-known different chemical properties. Furthermore, new QUENCHER assays to measure scavenging capacity against superoxide, hydroxyl, and lipid peroxyl radicals were developed. Calibration models showed good linearity (R(2) > 0.995), proportionality and precision (CV < 6.5%), and acceptable detection limits (<20.4 nmol Trolox equiv). The presence of ethanol in the reaction medium gave antioxidant capacity values significantly different from those obtained with water. The dilution of samples with powdered cellulose was discouraged because possible interferences with some of the matrices analyzed may take place.

Evaluation of Phenolic Antioxidant Capacity in Grains of Modern and Old Durum Wheat Genotypes by the Novel QUENCHERABTS Approach

The QUENCHERABTS (QUick, Easy, New, CHEap and Reproducible) approach for antioxidant capacity (AC) determination is based on the direct reaction of 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation with fine solid food particles. So, it may resemble the antioxidant action in foods or in human gastrointestinal trait. Here, the QUENCHER approach was used to study AC of durum wheat (Triticum durum Desf.) grains. Firstly, it was assessed which kind of antioxidants determines QUENCHER response. This has been performed by comparing AC measured by QUENCHERABTS and that measured by classical TEACABTS (Trolox equivalent antioxidant capacity) in four different extracts from whole flour of 10 durum wheat varieties containing: lipophilic, hydrophilic, insoluble-bound phenolic (IBP) and free-soluble phenolic (FSP) compounds. QUENCHERABTS data were unrelated to AC of water-extractable antioxidants and weakly correlated (r = 0.405, P < 0.05) to AC of the lipophilic ones; on the contrary, QUENCHERABTS response was mainly related to AC of IBP (r = 0.907, P < 0.001) and to a lesser extent of FSP extracts (r = 0.747, P < 0.001). Consistently, correlation was also found with the phenolic content of IBP and FSP (r = 0.760, P < 0.001 and r = 0.522, P < 0.01, respectively), thus confirming that QUENCHERABTS assay mainly assesses AC due to IBP. So, this assay was used in a first screening study to compare AC of bioactive IBP of thirty-six genotypes/landraces covering a century of cultivation in Italy. Interestingly, no relevant AC difference between modern and old genotypes was found, thus suggesting that a century of plant breeding did not decrease phenol-dependent health potential in durum wheat.

Use of phytochemomics to evaluate the bioavailability and bioactivity of antioxidant peptides of soybean β-conglycinin

This research investigates how in vitro digestion contributes to the release of antioxidant peptides crypted in soybean β-conglycinin (7S) and its deglycosylated form (D7S). It also investigates the uptake of the bioactive peptides by human intestinal Caco-2 cells using a bicameral system, and their effect on the antioxidant cell defense. Phytochemomics is used as a tool for achieving this goal. The peptides are obtained by mimicking human physiological gastrointestinal digestion conditions. The antioxidant capacity of the peptides is tested by ABTS•(+) radical cation decolorization (2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS)) and oxygen radical absorbance capacity assays. The antioxidant power of the peptides recovered from the basolateral chamber is also evaluated by an analysis of biomarkers of cellular oxidative stress such as cell proliferation, alkaline phosphatase, and secretion of nitric oxide, lipid peroxidation, superoxide dismutase and catalase. Peptides from D7S were more active than those of 7S in the modulation of the cell proliferation, oxidative status and differentiation of Caco-2 cells treated with H2 O2 . Differences in the bioactivity of the peptides of both proteins can be explained by analysis of the structural data obtained by mass spectrophotometry. Our findings support the bioavailability of antioxidant peptides of 7S. The antioxidant properties of 7S soy protein were influenced by events such as glycosylation, digestion, and absorption. Deglycosylation seems to be an innovative strategy for improving the properties of 7S. Deglycosylation might enhance 7S antioxidant power and reduce its immunoreactivity. The combined use of advanced analytical techniques and biochemical analyses (phytochemomics) has been a key part of this study.

The impact of the Maillard reaction on the in vitro proteolytic breakdown of bovine lactoferrin in adults and infants

The impact of the Maillard reaction on proteolysis of the bioactive bovine lactoferrin is comparedin vitrobetween adults and infants for the first time, coupling proteomics to elucidate bioactive peptide formation.

Direct measurement of total antioxidant capacity of cereals: QUENCHER-CUPRAC method

Polyphenols in cereal samples are distributed as free, soluble-esterified, and insoluble-bound forms either esterified or etherified to cell wall constituents. In the evaluation of total antioxidant capacity (TAC) of cereals, rather difficult and time-consuming acid, alkaline and enzymatic treatments of residue have been applied to complete the extraction of bound phenolic compounds. Thus, this work is aimed to measure the TAC of cereals (i.e. barley, wheat, rye, oat) by the 'QUENCHER procedure' (involving forced solubilization of bound phenolics by oxidizing TAC reagents) with the direct use of copper(II)-neocuproine (Cu(II)-Nc) reagent of the CUPric Reducing Antioxidant Capacity (CUPRAC) assay. In this novel 'QUENCHER-CUPRAC' method, reaction time and solvent composition parameters were optimized, and the method was applied to cereal samples with CUPRAC reagent dissolved in 1:1 (v/v) ethanol-water mixture. The antioxidant capacities of soluble and insoluble fractions were simultaneously measured to give a hierarchic TAC order of cereals as: barley>rye>oat>wheat. The TAC values of cereals measured by QUENCHER-CUPRAC were higher than those of original QUENCHER method using ABTS(•+) and DPPH reagents. Polyphenolic mixtures in a cellulose matrix gave additive TAC values with QUENCHER-CUPRAC. The proposed method correlated linearly with QUENCHER-ABTS(•+) (r=0.956) and QUENCHER-DPPH (r=0.976).

Total antioxidant capacities of raw and cooked meats

This study investigated the total antioxidant capacity (TAC) of meats (beef, chicken, pork and fish) and its changes on thermal treatment. The QUENCHER procedure, which is performed directly on the solid material without extraction, was selected and proved to be particularly suitable for meat samples. The ABTS(+) scavenging capacity of raw meats ranged between 25.9±1.0 and 51.7±1.2 mmol Trolox Eq./kg. Raw chicken had the highest TAC followed by pork, beef and fish. Upon heating at 180°C, TAC of meats increased to an apparent maximum at 5 min followed by sudden decreases until 15 min, while the final stage of heating was characterized by slight increases. The modifications of TAC during cooking can be explained considering factors such as denaturation and exposure of reactive protein sites, degradation of endogenous antioxidants and the formation of Maillard reaction products having antioxidant properties.