RU2169761C1 - Method of improving quality of baker's yeast - Google Patents

Abstract

FIELD: food industry. SUBSTANCE: citric acid and yeast milk are added in the final stage of commercial yeast production before filtration and forming. Amount of citric acid represents 0.1-0.5% volume of yeast milk being treated. Treatment is carried out for 1 h or longer at constant stirring. EFFECT: increased shelf life of yeast. 2 cl, 2 tbl, 2 ex

Description

 The invention relates to food biotechnology and can be used in enterprises producing baker's yeast.

 A known method for the production of pressed baker's yeast based on a technically pure culture of yeast-saccharomycetes, in which to suppress bacteria in seed yeast, it is recommended to use their treatment with one of these substances: lactic acid, a mixture of lactic and boric acids, furazolidone, hydrogen peroxide instead of sulfuric acid [ Typical technological regulations for the production of baking yeast. - M .: "Light and food industry", 1983. - S. 43, 51, 248-250].

 The known method, purifying seed yeast from a bacterial infection, does not guarantee its absence in marketable yeast. Due to the presence of bacteria in marketable yeast, their quality characteristics, such as resistance, shelf life and yeast lift, are reduced.

A known method for the production of baker's yeast, in which in order to improve the environmental safety of production without compromising the quality of the target product involves culturing them on a nutrient medium, isolating biomass from the culture fluid, introducing citric acid into the biomass in an amount of 0.0001-0.02% by weight of dry yeast substances followed by dehydration of the resulting biomass [RF patent 2104303, IPC ⁶ C 12 N 1/18. Method for the production of baker's yeast / T.V. Tulyakova, V.G. Andreev and others; LLC "RATURE". - N 97108293/13; Claimed 05/30/97; Publ. 02/10/98 - 2 s. ].

 The known method proposes to replace sulfuric acid, in the known case of its use in the production of yeast with citric acid. The invention solves the problem of improving the environmental safety of production.

 Existing technologies for the production of baker's yeast cannot provide an increase in their shelf life, more than guaranteed by GOST 171-81 and equal to 12 days.

 The technical result of the claimed invention is a significant improvement in the quality characteristics of baker's yeast, their durability and shelf life.

 The specified technical result is achieved by the implementation of the proposed method.

 A method for improving the quality of baker's yeast involves their production by cultivation in a nutrient medium containing sources of carbon, nitrogen, phosphorus, micro and macro elements using food citric acid in the production technology. The resulting biomass of yeast is isolated from the medium and subsequent processing is carried out in accordance with the technological mode of production to obtain marketable yeast milk. Commodity yeast milk at the final stage of production before serving for filtration and / or pressing is additionally treated with citric acid.

 Citric acid is introduced into marketable yeast milk in an amount of 0.1-0.5% of the volume of marketable yeast milk, or in an amount of 0.4-2.0% by weight of dry matter of yeast.

 Citric acid is introduced into commercial yeast milk as an aqueous solution.

 Commodity yeast milk with a solution of edible citric acid introduced into it is kept under continuous stirring for at least 1 hour, after which it is served for filtration and then molded and packaged.

 The impact of citric acid in accordance with the claimed method at the stage of completion of production of commercial yeast significantly improves their quality characteristics.

 Processing with citric acid improves the color of the yeast, its plasticity, facilitates molding, improves their organoleptic characteristics.

 The resistance of yeast made by the present method is increased compared to the norm by 24-136 hours. The lifting power of the yeast is improved.

Storage at a temperature of 4-8 ^o C provides yeast resistance of more than 720 hours with 240 hours allowed by GOST. In this case, the organoleptic characteristics and the lifting force of the yeast remain within normal limits.

 Storage of the treated yeast at room temperature increases the resistance of the yeast by 89-96 hours compared to standard.

 In 1998-1999 the authors conducted research on the dependence of the durability of commercial products manufactured by JSC "Yeast Plant" in Irkutsk on various factors. The results of the work showed the following. A direct relationship between an increase in the number of putrefactive bacteria and a decrease in the durability of the finished product is determined. Other groups of microorganisms (leukonostock, lactic acid and extraneous) to a lesser extent affect the resistance of the produced yeast.

 No direct dependence of trehalose content on yeast resistance was observed. Often, yeast contained a low percentage of trehalose, while maintaining high resistance.

 Table 1 shows the acidity, lift, resistance of the produced yeast and the content of trehalose in them when exposed to yeast milk with citric acid at various percentages of it to the volume of yeast milk.

 The best indicators are yeast treated with citric acid in an amount of 0.25% of the processed volume of yeast milk.

 In addition, after 7 days of storage of yeast, their acidity decreases, and the lifting force at different concentrations of citric acid varies in different ways, but does not deteriorate.

 The microbiological characteristics of commodity yeast under the conditions of the experiment conducted in August 1998, in thousand cells / g are shown in table 2.

 The results showed that the development of putrefactive bacteria, leukonostock, and to a lesser extent lactic acid and extraneous ones, is more suppressed.

 Increasing the acidity of yeast after treatment with citric acid at the stage of yeast milk does not reduce the lifting force, significantly improves the resistance of the yeast, almost does not change the content of trehalose, and in some cases increases its content in yeast.

 The proposed method of inhibiting the development of undesirable microorganisms in marketable yeast using food citric acid can improve the resistance and presentation of the yeast in an inexpensive and environmentally friendly way.

 The method is simple in practical implementation and slightly affects the cost of products.

 Example 1

 Yeast is produced in accordance with the technological regulations and technological instructions of the enterprise in a multi-stage way. Yeast mass is grown in a nutrient solution containing all the elements necessary for this. The resulting yeast biomass is separated from the medium, washed and concentrated to obtain yeast milk. 1.0 kg of edible citric acid is added to the 1,000-liter commercial yeast milk obtained at the final stage of production, having previously dissolved it in purified boiled water.

 After the introduction of a solution of citric acid, the yeast milk is kept with constant stirring for at least 1 hour, and then served on vacuum filters and molding.

 Example 2

 The production of yeast to the stage of obtaining marketable yeast milk is carried out in accordance with example 1. After receiving yeast milk, a solution of citric acid is introduced into the container with it, the amount of which is 0.25% of the volume of yeast milk. Next, extract the yeast milk with stirring for 1 hour. Processed yeast milk is fed to vacuum filters, the resulting yeast mass is molded and packaged.

 The application of the proposed method at JSC "Yeast Plant" (Irkutsk) in the production of iodized and non-iodized yeast allowed the plant to significantly increase the shelf life and sale of products - up to 24 days from the date of issue. The resistance of the yeast in this case was at least 72 hours.

Claims (2)

 1. A method of improving the quality of baker's yeast in the production of cultivation on a nutrient medium using citric acid technology, characterized in that the yeast milk is treated with citric acid in the form of an aqueous solution at the final stage of yeast production with subsequent release from excess moisture to the required limits, with this amount of citric acid is 0.1-0.5% of the volume of processed yeast milk.  2. The method according to claim 1, characterized in that the processing time of yeast milk is at least an hour with constant stirring.

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