Content of Total Phenolics, Flavan-3-Ols and Proanthocyanidins, Oxidative Stability and Antioxidant Capacity of Chocolate During Storage

Antioxidant (AO) capacity of chocolates with 27, 44 and 75 % cocoa was assessed after production and during twelve months of storage by direct current (DC) polarographic assay, based on the decrease of anodic current caused by the formation of hydroxo-perhydroxyl mercury(II) complex (HPMC) in alkaline solutions of hydrogen peroxide at potentials of mercury oxidation, and two spectrophotometric assays. Relative antioxidant capacity index (RACI) was calculated by taking the average value of the AO assay (the sample mass in all assays was identical). Oxidative stability of chocolate fat was determined by differential scanning calorimetry. Measured parameters and RACI were correlated mutually and with the content of total phenols (Folin-Ciocalteu assay), flavan-3-ols (vanillin and p-dimethylaminocinnamaldehyde assay) and proanthocyanidins (modified Bate-Smith assay). During storage, the studied functional and health-related characteristics remained unchanged. Amongst applied AO assays, the DC polarographic one, whose validity was confirmed by two-way ANOVA and F-test, correlated most significantly with oxidative stability (oxidation onset temperature and induction time). In addition, principal component analysis was applied to characterise chocolate types

Sensory and color properties of dietary cookies with different fiber sources during 180 days of storage

The aim of this study was to examine the sensory properties of dietary cookies produced with addition of different dietary fiber sources (inulin and oligofructose, oat flakes, mixture of oat flakes and whole meal flour, whole meal flour and mixture of whole meal flour and carob flour), and to measure instrumentally color changes of cookies upper and lower surfaces, after storage at temperatures of 18-20 °C for 180 days. Addition of inulin and oligofructose was determined to be the fiber source with the highest impact on sensory properties. Storage for 180 days expressed the highest influence on texture properties of dietary cookies regardless of applied dietary fiber source. Color differences calculated from measured color properties (psychometric light, L*, psychometric tone, a*, and psychometric chrome, b*) between products including different fiber sources were noticeable to extremely noticeable among products, with the most expressed difference was registered for products containing carob flour.Cilj istraživanja je ispitivanje senzornih karakteristika dijetetskog keksa proizvedenog sa dodacima dijetetskih vlakana iz različitih izvora (inulin i oligofruktoza, ražene pahuljice, mešavina raženih pahuljica i integralnog brašna, integralno brašno i mešavina integralnog brašna i brašna rogača) i instrumentalno merenje promena boje gornje i donje površine keksa, korišćenjem "Minolta" Chroma meter CR 400 tristimulus colorimeter tokom skladištenja na temperaturi od 18-20 °C do 180 dana. Za dodatak inulina i oligofruktoze je utvrđeno da je izvor dijetetskih vlakana koji je najviše uticao na senzorna svojstva. Skladištenje od 180 dana imalo je najveći uticaj na teksturne promene dejetetskog keksa, nezavisno od izvora dijetetskih vlakana. Razlike u boji izračunate na bazi instrumentalno merenih svojstva boje proizvoda (L*, a*, b*) izmeću proizvoda različitog sastava u pogledu izvora dijetnih vlakana su bile izražene do ekstremno izražene, sa najupečatljivijim razlikama registrovanim u slučaju dodatka brašna od rogača

Antioxidant efficiency of polyphenols from coffee and coffee substitutes-electrochemical versus spectrophotometric approach

Antioxidant (AO) capacity of instant, espresso, filter and Turkish/Greek coffee brews, coffee substitutes (roasted chicory root, barley, pea, chickpea, carob and dried fig) and individual compounds (phenolic acids, flavonoids, methylxanthines, N-methyl pyridinium and HMW melanoidins) was assessed using DC polarographic assay based on decrease of anodic current originating from hydroxo-perhydroxo mercury complex formed in alkaline solutions of H2O2 at potential of mercury dissolution, as well as three spectrophotometric assays (DPPH, ABTS and FRAP). A large difference between applied assays ability to recognize various types of individual AOs was noticed. Only according to DC polarographic assay significant AO activity was ascribed to methylxanthines and N-methyl pyridinum. The total content of phenolics (TPC) present in complex samples was determined by FC assay. The highest TPC was ascribed to instant coffees and coffee substitutes while the lowest to decaffeinated filter coffee. Complex samples were grouped based on principal components analysis, phenolics AO coefficient, calculated as the ratio between AO capacity and TPC, and relative AO capacity index (RACI), calculated by assigning equal weight to all applied assays including FC. The highest values of RACI were ascribed to instant coffee brews, followed by substitutes while the lowest to the decaffeinated espresso coffee