Quality parameters of fermented kvass extract
Keywords:kvass extract, evaporation, kvass drink, sensory evaluation
The aim of this research was to compare the commercially available kvass concentrate to the kvass extract which was experimentally produced from the naturally fermented kvass. Dry matter was determined according to the standard ISO 2173:2003, active acidity – ISO 10523:2012, and apparent viscosity was measured with a DV-III Ultra Brookfield rheometer, using a spindle SC4-18 with the speed 50 rpm at 26.9 °C. Sugars were determined using high-performance liquid chromatography. The sensory evaluation of kvass drinks (recombined kvass concentrate and extract) was performed according to the ISO 4121:2003. The dry matter content in the kvass concentrate (Ltd. Ilgzeem) was 69 %; it was diluted with distilled water to the dry matter content 32.4 ± 0.2 % of kvass extract (made from Ltd. Liepzeme kvass). Active acidity in the kvass concentrate was significantly (p = 0.012) lower (pH 2.86) than in the kvass extract (pH 4.18). Apparent viscosity in the kvass extract was 13.68 mPa×s and in the kvass concentrate 5.22 mPa×s. Major sugars in the kvass extract were fructose and glucose and in the commercial kvass concentrate – fructose. Hedonic evaluation showed that there were no significant differences (p > 0.05) in the preference of kvass drinks. The intensity of aroma, flavour and acidity was significantly more pronounced in the kvass drink made from the commercial kvass concentrate.