Production of lactic acid wort-based beverage with raspberry seed oil addition under static and dynamic conditions

Abstract

Wort-based beverages produced by lactic acid fermentation showed high nutritional value and functional properties but their flavor was not well accepted by consumers. Therefore, raspberry (Rubus idaeus L) seed oil in concentration of 0.0375% (v/v) was used in order to improve beverage flavor and to increase its biological value. Fermentation was carried out in bottles (static conditions) and in a stirred tank bioreactor (dynamic conditions) at 25°C. The effect of raspberry seed oil addition was investigated by measuring the content of lactic acid bacteria cells, the pH, the phenolic compounds and the antioxidant activity of the beverages with raspberry seed oil addition and the control sample without oil addition. Results showed that stirring increased fermentation rate but led to a decrease in the phenolic compounds content and the antioxidant activity of the beverages produced. Nevertheless, all beverages can be classified as functional because the concentration of lactic acid bacteria was over 107 cells/mL. Our results indicated that functional lactic acid wort-based beverage with improved biological value and flavour can be produced in static fermentation by adding 0.0375% raspberry seed oil.