This study aims to determine the effect of temperature and light UV on the colour photostability of astaxanthin microcapsule. Astaxanthin from shrimp shells, extracts by microwave assisted extraction using NADES as the solvent. The optimal conditions obtained were, a microwave power of 180 W, an extraction time of 5 minutes, and ratio NADES shrimp shell powder 8: 1 mL/g with yield astaxanthin of 7,466 ppm. Astaxanthin is purified using petroleum ether and dehydrated with anhydrous natrium sulphite. The purification results showed an increase in the brightness of the astaxanthin colour, expressed in L * 48.70 and an h value of 73.12. In order to maintain their photostability colour, astaxanthin is encapsulated with nano chitosan. The astaxanthin microcapsules were characterized by SEM, EDX, FTIR, and XRD, for chemical structure, morphological, and crystallization observation. It was reported that a photostability astaxanthin microcapsule was slightly enhanced. The test results showed that the colour of the astaxanthin microcapsules did not change after 30 minutes of UV exposure. The heat resistance test also shows that at 200° C the colour of astaxanthin microcapsule turns brown due to the solvent and the water in the astaxanthin microcapsule evaporates.

Cu2O is known as a potential photocatalyst material that work in visible light region due to its narrow bandgap energy. In this study, to improve photocatalytic activity and photostability, the...

<p>This research had been carried out on the analysis of nitrite and nitrate in bread by UV-Vis spectrophotometry through a diazotization reaction. The research began by determining the optimum conditions for nitrite analysis while nitrate needs to be reduced using Zn powder or spongy cadmium so it can be analyzed by UV-Vis spectrophotometry. Ionic interference could affect nitrite analysis using UV-Vis spectrophotometry, then both nitrite and nitrate analysis methods were validated based on the method validation parameters. The diazotization reaction produced an azo compound which have λmax 546 nm. The validation results showed that the linearity of nitrite and nitrate has R² = 0.9990 in the range 0-1 mg L^-1 with a molar absorptivity value for nitrite without a reduction process was 3.37 × 10⁴ L mol^-1 cm^-1, meanwhile 2.91 × 10⁴ L mol^-1 cm^-1 and 3.83 × 10⁴ L mol^-1 cm^-1 was shown for the reduced nitrite of Zn powder and spongy cadmium. The detection limits were 4.29 × 10^-3, 9.34 × 10^-3 ,and 7.58 × 10^-3mg L^-1 .The %RSD results were 0.31-1.83% with recovery percentage of nitrite and nitrate in the range of 83.2-104.4%. The strongest ionic interference was shown by Fe²⁺ and Fe³⁺ ions at concentrations &lt; 10 mg L^-1. WHO has confirmed that the daily intake for nitrate that is acceptable to be consumed by human is 0-3.7 mg/kg.</p>

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