Silver (Ag) and zinc (Zn) are very powerful antimicrobial metals. Therefore, in this research, a high-throughput, sensitive, and rapid method was developed for the determination of Ag and Zn in microcapsules using inductively coupled plasma mass spectrometry (ICP-MS). The sample preparation procedure employed simple microwave digestion of the microcapsules with 55.55% v/v HNO₃ and 44.45% v/v H₂O₂. The method was applied to determine Ag and Zn in microcapsule samples of different sizes (120 and 450 μm) after their preparation with and without chitosan. Prepared microcapsules, after characterization, were bonded to a polymer carrier by sol-gel procedure and the materials were characterized by FTIR spectroscopy and high-resolution optical microscopy. Significant differences were found in Ag and Zn levels between microcapsules samples prepared with and without chitosan. The results have shown that samples with chitosan had up to 20% higher levels of Zn than Ag: 120 μm microcapsules contained 351.50 μg/g of Ag and 85.51 μg/g of Zn, respectively. In contrast, samples prepared without chitosan showed larger overall variability: In microcapsules with a diameter of 120 μm, the amounts of antimicrobial metals were 98.32 μg/g of Ag and 106.75 μg of Zn, respectively. Moreover, 450 μm microcapsules contained 190.98 μg/g of Ag and 121.35 μg/g of Zn. Those quantities are high enough for efficient antimicrobial activity of newly prepared microcapsules, enabling the application of microcapsules in different antimicrobial coatings.

Mandarins are the second most farmed citrus. Consumers demand a mandarin fruit that is both tasty and excellent in quality. The fruit quality, flavonoid profile, antioxidant capacity and total carotenoid content of five varieties (‘Zorica’, ‘Chahara’, ‘Kawano Wase’, ‘Owari’ and ‘Saigon’) of Satsuma mandarins grown in Neretva valley (Croatia) were determined. In this research, the distribution of bioactive compounds was different for mandarin juice, dry pulp residue and dry peels. Dry peels showed higher levels of polyphenolic compounds and antioxidant activity. Total carotenoids were found to be in a greater concentration in dry pulp residue than in the dry peel. The highest levels of total carotenoids (543 μg β-carotene/g) were found in the dry pulp residue of ‘Owari’ and ‘Saigon’, while the lowest levels were in ‘Chahara’ (227.87 μg β-carotene/g). In dry mandarin peels, the highest levels of total carotenoids were in ‘Kawano Wase’ (227.58 μg β-carotene/g), and the lowest levels were in ‘Chahara’ (52.24 μg β-carotene/g). The most abundant component of polymethoxyflavones (PMFs) in mandarin dry peel was nobiletin, ranging from 0.204 mg/g (‘Chahara’) to 0.608 mg/g (‘Saigon’), followed by tangeretin, ranging from 0.133 mg/g (‘Chahara’) to 0.251 mg/g (‘Saigon’), and sinesestin (‘Zorica’), ranging from 0.091 mg/g to 0.353 mg/g (‘Saigon’).