The effects of lycopene, lutein, annatto, and γ-tocopherol were examined on autoxidized triglycerides. Oxidation was followed by measuring hydroperoxide formation as peroxide value. The loss of the orange color of carotenoids was followed spectrophotometrically. Lutein and lycopene were prooxidants, whereas the natural food color annatto and γ-tocopherol effectively inhibited hydroperoxide formation. By adding γ-tocopherol, the prooxidant effect of carotenoids was inhibited and loss of yellow carotenoid color was retarded. Moreover, a combination of lutein and γ-tocopherol was more efficient than γ-tocopherol in inhibiting the hydroperoxide formation of triglycerides. The benefit of a combination of a carotenoid and tocopherol as an antioxidant may be due to the effect of γ-tocopherol to retard the formation of degradation products of the carotenoid. The results suggest that potential prooxidant effects of carotenoids should be considered when carotenoids are proposed for color in lipid-containing foods. Keywords: Lutein; lycopene; annatto; γ-tocopherol; autoxidation; color; antioxidant

Effects of physical state and glass transition on nonenzymatic browning rate in water, glycerol, poly(vinylpyrrolidone) (PVP), and maltodextrin (MD) systems were studied. All systems had the same concentration of reactants, glucose and lysine, in the water phase. The systems, except water, had also comparable water activities (0.33). Sorption isotherms and glass transition temperatures (T g) at various water contents for the freeze-dried PVP and MD systems were determined. Nonenzymatic browning rate was determined at several temperatures from optical density at 280 and 420 nm. The PVP and MD systems contained 12.9 and 8.2 g of H2O/100 g dry matter and had T g values of 67 and 62 °C at 33% relative humidity and 24 °C, respectively. The liquids exhibited significantly higher browning rates than the concentrated systems, especially below the T g values. The browning rate was higher in the PVP than in the MD system, suggesting that a possible phase separation may affect nonenzymatic browning in foods. Keywords: Glass transition; nonenzymatic browning; physical state; reaction rate

Raw materials affect formation of biogenic amines in dry sausages. Effects of thawing time of raw materials and amine-negative starter culture on amine formation were studied on a pilot scale. The levels of biogenic amines, precursor amino acids, pH, water activity, and microbial counts were measured. Use of starter culture significantly decreased levels of histamine, tyramine and cadaverine formed. The effect of thawing time on formation of biogenic amines was dependent on the use of starter culture.

Applicability of a method for studying glass transition and reaction rates was evaluated. Water sorption of maltodextrin and poly(vinylpyrrolidone) based food models having lysine and xylose as reactants were determined gravimetrically at 4 temperatures. Data were modeled using the Guggenheim-Anderson-DeBoer (GAB) equation, isosteric heats of sorption were calculated, and water activity shift with temperature was evaluated using the Clausius Clapyeron equation and the GAB equation that included the effect of temperature (the GAB(T) equation). Within a 100 8C temperature range, water activity shift with temperature could not solely explain different reaction rates. Storage of food models in sealed containers can be applied in studies of glass transition and reaction kinetics.

Effects of a reducing sugar, fructose, glucose, or xylose, and glass transition on the nonenzymatic browning (NEB) rate in maltodextrin (MD), poly(vinylpyrrolidone) (PVP), and water systems were studied. Glass transition temperatures (T(g)) were determined using DSC. Water contents were determined gravimetrically, and NEB rates were followed at several temperatures spectrophotometrically at 280 and 420 nm. Reducing sugar did not affect water contents, but xylose reduced the T(g) of the solid models. Sugars showed decreasing NEB reactivity in the order xylose > fructose > glucose in every matrix material. The NEB reactivity and temperature dependence of the single sugars varied in different matrices. The NEB rates of the solid models increased at temperatures 10-20 degrees C above the T(g), and nonlinearity was observed in Arrhenius plots in the vicinity of T(g). The temperature dependence of nonenzymatic browning could also be modeled using the WLF equation.