Comparison of volatile compounds and sensory profiles of alcoholic black currant (Ribes nigrum) beverages produced with Saccharomyces, Torulaspora, and Metschnikowia yeasts.

Black currants (Ribes nigrum) were fermented with Saccharomyces and non-Saccharomyces yeasts without added sugar to yield low-ethanol-content beverages. The effects of yeasts on the volatile compounds and sensory characteristics were analysed by HS-SPME-GC-MS, GC-O, and generic descriptive analysis. Ninety-eight volatile compounds were identified from the black currant juice and fermented beverages. Significant increases in the contents of esters (131 %), higher alcohols (391 %), and fatty acids (not present in juice sample) compared to initial juice were observed depending on the yeasts used. GC-O analysis revealed the higher impact of esters on the sensory properties of Saccharomyces bayanus-fermented beverage compared to the Torulaspora delbrueckii-fermented beverage. In the sensory evaluation, non-Saccharomyces yeasts resulted in a higher 'black currant odour'. However, all beverages were intensely sour, which can be a significant challenge in the development of alcoholic berry beverages.

Multiphase matrix of silica, culture medium and air for 3D mammalian cell culture.

The craving for multiphase materials with adjustable properties for mammalian cell encapsulation persists despite intensive research on 3D cell culture and tissue engineering. This interest is incited by the complex interaction between cells and different materials, various manufacturing methods, cell chip applications, and the aspiration to abolish animal experiments. This study aims to show the feasibility of preparing a stable multiphase material for prolonged mammalian cell embedment and 3D cell culture. The material comprises silica as the solid phase, cell culture medium with serum as the main liquid phase and air as the gas phase. The silica sol-cell culture medium-serum mixture was foamed, and it turned into a stable foamed hydrogel. The stability, flow properties and foaming parameters were studied by rheological and surface tension measurements. The viability of embedded cells was studied by measuring the metabolic activity at different time points. Their sensitivity to the surrounding conditions was compared to cells grown in monolayers by exposing them to a toxic compound. A stable foamed hydrogel with cell culture medium as the main liquid phase was prepared. Based on oscillatory measurements, the foamed hydrogel stays stable for at least 6-7 weeks and the embedded mammalian cells remain viable for the same time period. Appropriate surface tension and viscosity were crucial for an at least twofold volume increase by foaming, which is necessary for the mammalian cells to survive and proliferate. A test with a toxic compound reveals a difference in the sensitivity of cells in monolayer cultures versus embedded cells.