Oak Leaves as a Raw Material for the Production of Alcoholic Fermented Beverages

This study aimed to point out the possible use of oak leaves (Q. petraea) in the production of fermented alcoholic beverages. Parameters such as antioxidant capacity, total phenolic content, phenolics and sugars were determined using spectrophotometric and chromatographic methods. pH values were also determined, and in the final product with a fermentation length of 85 days, the alcohol content was determined and sensory analysis performed. The antioxidant capacity of the beverage was lower compared to the infusions before fermentation, and its highest values were recorded in the leaf samples, in which the highest values of phenolic compounds and the total phenolic content were also recorded. A decrease in the content of total phenolics was recorded with the increasing length of fermentation in beverage samples. However, the fermentation process had a positive effect on the contents of some phenolic substances such as catechin, gallic acid and gallocatechin. Sensory analysis showed a higher acceptability of the fermented beverage without the addition of orange, which could be caused by the higher sugar content in these samples. Oak leaves therefore represent a suitable raw material for the production of a fermented alcoholic beverage, without the need to enrich the taste with other ingredients

Determination of Thermostability Degree of Lycopene in Watermelon (Citrullus lanatus)

The aim of the work was to determine the degree of watermelon (Citrullus lanatus) thermostability according to the content of the present bioactive compounds and antioxidant properties. The watermelon samples were exposed to the following temperatures/time regimes: 40, 70, and 100 °C; 2, 5, and 15 min. The sample characteristics were monitored by spectrophotometric and chromatographic methods. Statistically significant (p < 0.05) differences were observed between the heat-treated samples compared to the heat-untreated control sample; differences were found almost between all samples. The total polyphenol content increased in all heat-treated samples. The highest total polyphenol content was observed among samples treated at 40 °C for 15 min (1.38 ± 0.01 mg/g). Lycopene content (measured by spectrophotometer) also increased in the same samples exposed to 40 °C for 5 min (65.45 ± 0.20 mg/kg), though higher temperatures (70 and 100 °C) resulted in lycopene degradation. Chromatographic method (measured by high-pressure liquid chromatography) showed lycopene degradation after each heating treatment. Not unambiguously, results and observations were not found in antioxidant activity due to oscillations in measured bioactive compounds. The obtained results emphasize processes in heat-treated watermelon, and they can be useful in the production of different products where this food commodity can be included