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SummaryThe reaction system for octyl-β-glucoside synthesis catalysed by the almond-β-glu cosidase has been characterised. The monophasic octanol saturated with diff erent amounts of water served as a reaction medium. Both the glucose and the activated substrate p-nitrophenyl-β-glucoside were examined as glycon donors. The reverse hydrolysis and the transglycosylation were both used as reaction models for this enzymatically catalysed alkyl-β-glucoside synthesis. The rate of synthesis of octyl-β-glucoside (v S ), the rate of hydrolysis, i.e. the glucose formation (v H ) and the predicted yield (Y) were determined. The eff ect of water activity on the synthetic and hydrolytic activity of the enzyme was investigated. Both the rate of synthesis and the rate of hydrolysis increased with the increase of the water activity in the reaction system, showing their maximum values at the water activity close to the saturation level. Thus, the maximum ratio of v S /v H =0.165 was achieved at the water activity of 0.94. The predicted yields were 0.5, 0.75 and 14.19 % and were lower than the actually achieved yields of 19.45, 38 and 36.40 % at the water activities of 0.75, 0.84 and 0.94, respectively. The yield of octyl-β-glucoside in the reverse hydrolysis was only 15.2 %, i.e. 3.25 times lower than the yield obtained in the transglycosylation reaction with the water activity of 0.94. The solubility of glucose in pure octanol was only 1.5 mmol/L at the saturation level of 12 mmol/L in the presence of 10 mmol/L of p-nitrophenyl-β-glu coside, and it increased to 15.5 mmol/L in the presence of octyl-β-glucoside.

Almond b-glucosidase was used to catalyze the transglycosylation of p -nitrophenyl-b-D-glucoside to alkyl glucosides, with hydrolysis to glucose as a side reaction. The conversions were carried out in alcohols with varying water contents below water saturation. Both the total reaction rate and the ratio between the transglycosylation and hydrolysis increased with increasing water activity, and at a fixed water activity in the different alcohols, rate and transglycosylation/hydrolysis ratio increased in the following order: 1-octanolB1-hexanolB1-butanol. Synthesis of alkyl glucosides by transglycosylation in monophasic alcohol media is thus most favorable for short chain alcohols, and should be carried out at high water content.

SummaryThe reaction system for octyl-β-glucoside synthesis catalysed by the almond-β-glu cosidase has been characterised. The monophasic octanol saturated with diff erent amounts of water served as a reaction medium. Both the glucose and the activated substrate p-nitrophenyl-β-glucoside were examined as glycon donors. The reverse hydrolysis and the transglycosylation were both used as reaction models for this enzymatically catalysed alkyl-β-glucoside synthesis. The rate of synthesis of octyl-β-glucoside (v S ), the rate of hydrolysis, i.e. the glucose formation (v H ) and the predicted yield (Y) were determined. The eff ect of water activity on the synthetic and hydrolytic activity of the enzyme was investigated. Both the rate of synthesis and the rate of hydrolysis increased with the increase of the water activity in the reaction system, showing their maximum values at the water activity close to the saturation level. Thus, the maximum ratio of v S /v H =0.165 was achieved at the water activity of 0.94. The predicted yields were 0.5, 0.75 and 14.19 % and were lower than the actually achieved yields of 19.45, 38 and 36.40 % at the water activities of 0.75, 0.84 and 0.94, respectively. The yield of octyl-β-glucoside in the reverse hydrolysis was only 15.2 %, i.e. 3.25 times lower than the yield obtained in the transglycosylation reaction with the water activity of 0.94. The solubility of glucose in pure octanol was only 1.5 mmol/L at the saturation level of 12 mmol/L in the presence of 10 mmol/L of p-nitrophenyl-β-glu coside, and it increased to 15.5 mmol/L in the presence of octyl-β-glucoside.

The aim of this work was to investigate the possibility for the development of new meat cured products with a decreased nitrite content, but unchanged sensory characteristics and prolonged shelf life. Thus, the possibility to replace or to decrease the amount of the nitrite salt by including other non-toxic additive in the product making process was investigated. The effects of different recipes on both sensory characteristics and microbiological safety of the meat products were evaluated. The results showed that even with a very low concentration of nitrite salt, but in presence of monolaurin, the desired pink nuance of the meat batter could be achieved. When half of the amount of nitrite salt (0.2%) was replaced with 0.72% of monolaurin, the meat product, collagen packed sausage with both good sensory properties and microbiological safety was produced. Thus prepared product showed the 21 times lower value for the total cell count of the bacterium Bacillus subtilis D-TMF compared to the product with only nitrite salt as a food additive.