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The residues of artichoke processing are commonly discarded by the food industry owing to lack of detailed knowledge of their chemical composition, which would facilitate research into practical uses for them. We therefore evaluated proximate and fatty acid compositions, total phenolic compound content and total antioxidant activity of artichoke parts (bracts, receptacle and spikes) cultivated in Brazil and performed principal components analysis. Analysis indicated higher concentrations of phenolic compounds and antioxidant activity in the spikes than in the bracts and receptacle. In a follow-up experiment we assessed the lipid protective value of artichoke parts in tests on canola oil using a new instrument, called “Oxitest”. The addition of 5 g/100 g of spikes almost doubled the canola oil induction point. These results suggest that artichoke spikes may have industrial applications as natural antioxidant additives to foods such as canola oil.

Response surface methodology was used to optimize the total phenolic content (TPC) result in white rice, using a new methodology that employed Fast Blue BB (FBBB) reagent, which reacts more specifically with phenolic compounds, along with direct QUENCHER procedure. This is the first time in which such conciliation between FBBB reagent and QUENCHER was done. The obtained model allowed to evaluate how the factors influenced the method linearity (R2), improving the choice of the optimal system condition. Furthermore, the similarity between experimental results and values generated by the model indicated the method validity within the studied region. Thus, the optimal condition determined in the present work was 30 min reaction time, 0.17 mL FBBB reagent and use of 5% NaOH as the catalyst for the reaction. This optimized condition suggested that the combination of the method, which used FBBB reagent and the direct QUENCHER procedure, was rapid and effective, yielding high TPC values (1488.73 mg of gallic acid equivalent per 100 g).

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.