RESUMO
The objective of this research was to compare the function of thymol-loaded nanostructured lipid carriers (NLC) and a thymol-nanoemulsion (NE) with nitrite (120 mg/kg) on quality parameters of sausage. The droplet size of the NLC and NE was 140 and 86.39 nm with encapsulation efficiency of 97 and 94%, respectively. The results on sausage showed that all samples containing NLC and NE exhibited the lowest increase in peroxide value, total volatile base-nitrogen, and TBA with the highest inhibitory effect on the growth of E. coli, C. perfringens, lactic acid bacteria, psychrophilic bacteria, mold and yeast, and total viable counts as well as good texture and sensory attributes with the best results in the NLC + nitrite and NE + nitrite samples. The L* and a* values were relatively higher in the samples treated with nitrite, NLC + nitrite, and NE + nitrite after 4-week storage. This increase in redness was associated with the maintenance of oxymyoglobin levels and a decrease in metmyoglobin production. The results of this study indicated that the combined use of NLC/NE (particularly NE) with 60 mg/kg nitrite significantly improved the oxidative and color stability, and delayed the spoilage and off-flavor in sausage.
RESUMO
Discharge of 2,4-dinitrotoluene (2,4-DNT) into the environment leads to a serious soil and water sources pollution problem, due to toxicity and possible carcinogenicity of this toxic substance. In this work, the photocatalytic degradation of 2,4-DNT was investigated using CoFe2O4/SiO2/TiO2 nanoparticles. The catalyst features were characterized by using XRD, TEM, EDX, UV-vis DRS, FTIR, and VSM techniques. The influence of different experimental factors on degradation efficiency including pH value, catalyst dosages, and initiate concentration of 2,4-DNT were investigated. Mineralization of the model pollutant was determined using TOC analysis under optimum conditions. A possible mechanism, process kinetic and reusability of magnetic photocatalyst were also performed. In optimum experimental conditions (pH=3, photocatalyst dosage=0.75 g/L, 2,4-DNT=0.025 g/L), degradation efficiency achieved 88.5% within 180-min reaction time with TOC removal of 55.6%. Dominate oxidizing radicals during the degradation of 2,4-DNT by CoFe2O4/SiO2/TiO2 were hydroxyl radicals. The photocatalytic degradation of 2,4-DNT followed first-order rate kinetics. After three successive use cycles, the degradation efficiency was reduced by 64%. Our results revealed that the synthesized CoFe2O4/SiO2/TiO2 photocatalyst was a good choice for degradation of 2,4-DNT, due to proper potential reusability and catalytic activity.
