METHOD FOR EXPRESS ASSESSMENT OF DRY BAKING YEAST QUALITY

摘要

FIELD: food industry.;SUBSTANCE: method involves the use of the detecting device "electronic nose" based on an array of 8 piezosensors with the basic oscillation frequency of 10-15 MHz, whose electrodes are modified with coatings sensitive to alcohols and carbon dioxide, for which purpose films made from acetone and toluene solutions, as well as from chloroform suspensions of carbon nanotubes, are applied to the electrodes, with the total weight of each coating after the solvent removal of 4-10 mcg; the signals of an array of piezosensors are registered in the real-time mode in the form of the "visual imprint"area (S^(τ)); to do this, 2 samples of dry baking yeast are weighed, the samples are transferred into the samplers, distilled water pre-heated to 37°C is added, and the resulting solutions are stirred; the further measurements are performed as follows: after 5 min, the equilibrium gas fraction above one sample of yeast water suspension is taken with a gas syringe, injected into the detection cell, and the signals of the piezosensors and S¹⁽⁵⁾are recorded during 1 min; after cleaning the detection cell and the piezosensors, the equilibrium gas fraction (EGF) is taken in an amount of 1 cm³ for 1-2 min and repeatedly after 5, 10 and 15 min, and S¹⁽¹⁰⁾, S¹⁽¹⁵⁾, S¹⁽²⁰⁾are recorded; 10 minutes after the time of the samples mixing, the solution of sucrose is introduced into the second sampler with the yeast water suspension; 5 and 10 min after, 1 cm³ of EGF is taken above the sample, the signals of the sensors array and S²⁽¹⁵⁾, S²⁽²⁰⁾ are recorded, and the changes of the areas of "visual marks" of the sensor array signals for the 15th and 20th minute of measurement (∆S⁽¹⁵⁾=S²⁽¹⁵⁾-S¹⁽¹⁵⁾, ∆S⁽²⁰⁾=S²⁽²⁰⁾-S¹⁽²⁰⁾) are calculated, reflecting the differences in the total content of volatile substances in the EGF over the samples while activating dry yeast with water and sucrose; to assess the dry yeast quality, the yeast quality indicator (YQI) is calculated as the difference of areas of "visual marks" on the 20th and 15th minutes of measurement (YQI = ∆S⁽²⁰⁾-∆S⁽¹⁵⁾), reflecting a change in the content of volatile substances in the EGF over the yeast sample during the process of their aactivation with sucrose; if YQI is less than 0±50, the conclusion about the low quality of the yeast is made.;EFFECT: simplification of determining the dry yeast quality in comparison with known techniques, along with significantly reducing the time and material costs.;1 ex, 2 tbl, 1 dwg