INFLUENCE OF TEMPERATURE REGIMES OF RIPENING AND FERMENTATION STAGES ON THE PHYSICAL AND CHEMICAL PROPERTIES OF CREAM AND SOUR-CREAM BUTTER QUALITY INDICATORS

Physical and chemical properties of cream multistep modes of ripening and fermentations are investigation and their role in the production of sour-cream butter is studied. The process of ripening of cream was carried out multistep, regimes were selected depending on seasonal changes in the composition of milk fat. For raw materials of the autumn-winter period, for the values of iodine number 29.1–34.5, the first stage of ripening was carried out at a temperature of 8°C for 2 hours, the second stage – at 21°C for 7 hours, the third stage – at 13°C for 10 hours. For raw of spring-summer period, for the values of iodine number 34.5–40.1, the first stage of ripening was carried out at 21°C for 6 hours, the second stage – at 13°C for 4 hours, the third stage – at 8°C for 8 hours. It has been established that individual modes of low-temperature cream preparation, taking into account seasonal changes in the composition of milk fat, make it possible to obtain cream before churning almost with the same indexes of effective viscosity. The content of the crystalline phase of milk fat under both temperature regimes was 38.7– 40.1%, which is sufficient to obtain of proper consistency sour-cream butter. The content of diacetyl and volatile organic acids more depend on the level of fermentation of cream than on the technological regimes of ripening and seasonality of raw materials. It has been proved that an increase in the fermentation degree of cream promotes an increase in the acidity of plasma and the content of aroma-producing components in the butter, and, accordingly, affects the degree of the sour taste. It is recommended for the production of cultured butter to begin the cream when the acidity of the plasma reaches 60oT, which ensures the formation of high sensorial characteristic of the finished product.


Introduction. Formulation of the problem
One of the challenging issues of the butter production industry is the revival of the production of sourcream butter.Production of original product was com-plicated by both the lack of domestic bacterial cultures production and the lack of scientific data for technological parameters of temperature conditions for processing dairy raw materials into cream for the churning.

Analysis of recent research and publications
Despite the obvious complexity of the technological stage associated with the prolonged ripening of cream, the sour-cream butter produced by classical technology, the knocking method, has significant taste advantages compared to the butter produced by the conversion of high-fat cream [1].
At the heart of the existing technology of sour-cream butter production by the method of whipping cream lies the ability of milk fat to change the aggregate state under the influence of temperature in parallel with the achievement of the required level of acidity and the formation of specific aromatic substances as a result of lactic fermentation by fermented cultures [2][3][4][5][6].
To regulate the structure of butter consistency and minimum fat loss in buttermilk, to strengthen the butter structure in the spring and summer seasons and to reduce mechanical strength at this time by ensuring proper flow and completing phase changes in milk fat glycerides during cream ripening, differentiated multistage temperature regimes of prolonged ripening of cream before beating, which are selected taking into account the chemical composition for the winter and summer periods [7][8][9].Typically, the cream maturation regime is selected depending on the iodine value to prevent consistency defects (excessive hardness, brittleness, brittleness [10].
Therefore, it is necessary to focus on such temperature regimes of cream ripening that could simultaneously provide necessary crystallization of milk fat and create optimal conditions for the functioning of the starter microflora, promote the accumulation of aromatic substances and produce butter with a characteristic taste and aroma and a good consistency [10][11][12][13].
Despite this, the bacterial cultures must be adapted to the temperature ripening conditions provided for by this technology and to ensure a gradual fermentation of the cream to the required acidity simultaneously with the achievement of a certain level of the crystallization phase of milk fat in cream.Only under such conditions is the guarantee of obtaining the desired product with characteristic acidic taste and excellent consistency.
In addition, for the accumulation of flavor and aromatic compounds, the level of fermentation of cream is important.It is known that with a low level of active acidity in cream, more compounds accumulate, which form the taste and aroma of the finished product.In particular, the aromatic component of diacetyl is actively produced when the cream reaches a pH of 4.5-4.7 units [14].
Therefore, due to bacterial cultures and the right choice of temperature regimes of maturation, it is possible to regulate biochemical and enzymatic processes in cream.In particular, the accumulation of lactic acid and aromatic compounds depends not only on the processability and biochemical activity of the selected bacterial cultures, but also on the degree of fermenta-tion of the cream, which affects the expressiveness of the flavor bouquet of the desired product.
It should be noted that the existing technology of producing sour-cream butter provides for the use of starter cultures.However, to date, increased attention is paid to production workers by bacterial preparations of direct application, which exclude the stage of preparation of the production starter.
In Institute of Food Resources has developed bacterial preparations for the production of sour-cream butter.The value of these crops lies in their ability to develop, aromatic and acid formation, the formation of moderate viscosity in cream at low temperatures, provided for this technology.The introduction of them into the industrial production of sour-cream butter requires verification of the above facts.
Given that active aromatization of lactic acid bacteria occurs only after the accumulation of a certain amount of lactic acid in the medium, it was important to establish the value of the titratable acidity of the cream cream before churning, providing the best organoleptic parameters of the final product.The purpose of the studyinvestigation the influence of stepped temperature regimes of maturation and the degree of cracking of the cream on the properties of the cream and the quality of the indicator of sour-cream butter.

Research materials and methods
Fermentation of the cream was carried out by previously activated for 3 hours bacteriai preparations of direct set in skim milk Direct application was done at the rate of 10 g/t.The strains of mesophilic lactococci Lactococcus lactis ssp lactis, Lactococcus lactis ssp.cremoris and Lactococcus lactis ssp.diacetilactis were involved in the bacterial preparation "Iprovit KVМ-С1".To the bacterial preparation "Iprovit KVМ-С2" strains of mesophilic lactococci Lactococcus lactis ssp lactis, and Lactococcus lactis ssp.diacetilactis are included.
In order to determine the degree of fermentation of cream, experimental butter production was carried out after reaching acidity of 50°T, 60°T and 70°T in the cream.
The titratable acidity of the cream during storage was determined by GOST 3624-92; active acidity (pH)potentiometric; the degree of crystallization of milk fatby volume dilatometry [15].The content of acid flavor in the butter was estimated by the amount of diacetylby the method of Zalashko and Makarina [16], volatile organic acidsafter distillation with water vapor.

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Volume 12 Issue 3/ 2018 For the production of butter, cream with fat 35% was pasteurized at a temperature of (92±2)°C.The finished products were stored at a temperature of (5±1)°C for 20 days.

Results of the research and their discussion
In the production of sour-cream butter, the acidity of the cream before churning is one of the main indicators, it determines the formation of a specific taste and aroma in the butter.The titrated acidity of the cream plasma is an indicator that quantitatively shows the activity of the ferment in cream, whereas measuring the active acidity of the cream does not give an accurate idea of the activity of the fermented microflora, since the cream is characterized by a certain buffer.
The duration of ripening of the cream before reaching the acidity of 50ºT, 60ºT and 70ºT was 14.5 17-18 and 21-22 h respectively.The change in the controlled indices in cream from the winter and summer cream ripening regimes is shown in Fig. 1-3.

Fig. 2. Change in the physical and chemical properties of cream for the "summer" ripening regime
Observations of the change in titratable acidity and pH during the fermentation of cream (Figure 1) showed that after 2 hours of fermentation at 8°C and subsequent exposure at 21°C for 1 hour, the initial pH (6.5 units) and titrated acidity (17ºT) cream did not change, which may be due to the adaptation of cells of It should be noted that the fermentation of the cream with the "Iprovit KVM-С1" bacon concentrate was delayed for 1 hour until the acidity reached 60-70°T.
Thus, it is shown that the value of acidity depends on the active vital activity of the fermented microflora.
The study of the phase transitions in cream with the change in the state of the system (viscosity, pH, solids content) over the winter time regime using starter cultures showed that during the first stage of fermentation of cream at 8°C the amount of solid phase reached 48.8%, active and titrated acidity, as well as the viscosity did not change and amounted to 6.5 units, respectively.pH, 17ºТ and (10.0-10.3)•10 - Pa•s.After heating to 21°C, the crystalline fat content was reduced to 48.4% and was maintained without significant changes until the next cooling.In particular, for a period of exposure from 3 hours to 6 hours, the amount of solid phase increased by only 2.4%.Despite a significant decrease in pH, the viscosity remained unchanged for about 6 hours.The main crystallization occurred at 13°C for 4 hours, but the equilibrium state only occurred after 8 hours with the hardened fat content 40.1%, while the fermentation of creams and the change in viscosity continued.
Our data shows that during the 2 hours of physical fermentation the bulk of high-and low-melting triglycerides crystallizes, that is, at sufficiently low temperatures of the first stage of preparation, not only the formation of crystallization centers occurs, but also the linear growth of crystals.For 1°C the process of crystallization occurs due to solidification of a limited number of triglyceride fractions without attracting low melting fractions.
Cooling cream at the first stage is necessary for the formation of a large number of crystallization centers.After the following temperature increase, which is most favorable for crystal growth, crystallization of high melting triglycerides occurs and liquid fat remains in the fat globules, from which only a small amount of crystals can form at a temperature above 10°C.
Thus, a sufficient amount of liquid fat is achieved in the finished product, which is a continuous liquid phase during whipping, which will ensure good spreadability and prevent the formation of a too dense product structure during the winter production period.
During the summer cream ripening first stage at 21°C, despite the decrease in active acidity in the 6.0-6.1 pH range and the increase in titratable acidity from 17 ºT to 23.5-24.0ºT,crystallization of the cream was observed on 6.8% without changing the viscosity for 4 hours.After cooling the cream to 13°C, the acidity growth rate decreased.The crystallization process during this period occurred quickly enough and slowed down after 2.5 hours of aging.At the end of 13°C, the content of the solid phase was 26.5%.
Cooling the cream to 8°C significantly slowed the growth of acidity, but led to an increase in crystalline fat of 1.5 times compared to the previous exposure at 13°Cup to 38.7%.It should be noted that the rate of solidification at this stage was lower than 13°C.The equilibrium state between the liquid and solid phases was reached after 6 hours.
Аccording to the summer method of preparation, the crystallization of milk fat was completed at a temperature of 8°C.Under these conditions, crystalline mixtures and mixed crystals containing low-and highmelting glycerides are formed.Due to not too much liquid fat, the remaining butter acquires a fairly dense consistency At the end of fermentation, the content of the crystalline phase of milk fat from both temperature regimes was 38.7-40.1%,which is sufficient to obtain a good consistency butter, since its optimal value should be 40±3% [3].
Thus, such individual modes of low-temperature cream preparation with different chemical composition will allow obtaining butter with almost the same content of solid phase and not significant differences in consistency.
According to the results of the effective viscosity of cream at a shear rate of 729 s -1 , ripening by the winter temperature regime, we can distinguish 3 conditional zones: 1 -the zone of decline (2-4 h); 2zone of relative stability (4-10 hours) 3zone of active growth (10-22 hours).

Fig. 3. Change the effective viscosity of the cream
during fermentation Keeping cream at elevated temperatures of 21°C for 2-4 hours it was observed a rapid decline in effective viscosityup to 8.0-8.3Pa•s in cream fermented with both bacultures.The following increase in viscosity is due to the denaturing of the protein phase of the cream as a result of active lactic acid synthesis by microorganisms.It should be noted that cooling the cream from 21°C to 13°C after 8 hours of exposure somewhat influenced their viscosity, but not significantly.
Within 18 hours of cream ripening in summer regime, a gradual increase in their viscosity was ob- served.However, the following exposure led to its rapid growth.A sharp increase in the viscosity of fermented cream after cooling is associated with the formation of milk fat crystals at a given temperature.As a result, the fat globules are destroyed and the amount of free fat increases, which directly affects the rheological parameters of the system.In general, with increasing duration of fermentation of cream, their viscosity increases.In the case of their 14-hour exposure to an acidity of 50°T, the effective viscosity was the lowest -10.5-17.0.By the end of the twenty second hour of fermentation the viscosity of the cream, regardless of the temperature regime, was almost at the same level: 26-28 Pa•s during fermentation with the bacterial preparation " Sprovit KVM-C1" and 19-22 Pa•s with the participation of "Іprovit KVM-C2".The formation of a viscous consistency can be explained by the biological features of the fermented " Iprovit KBM-C1" culture used, in particular the ability of L. cremoris to produce exopolysaccharides at low pH values of the plasma.Thus, it could be stated the influence of the activity of fermented microflora on the viscosity of cream.In particular, the introduction of a ferment allows for a slight increase in the viscosity of the cream during the ripening process, but with marginal energy costs when further machining them to produce cultured butter.
So we found the dependancy of cream fermentation in the titratable acidity of plasma 50ºТ, 60ºТ and 70ºТ on the level of flavoring substances of the manufactured cultured butter for winter and summer periods.It was noted that with increasing duration of fermentation and acidity of cream, their quantity increased.In particular, the concentration of diacetyl increased 1.6-1.7 times from 0.15-0.17mg/100 g to 0.24-0.28mg/100 g and from 0.14-0.16mg/100 g to 0.22-0.26mg/100 g in sour-cream butter produced from fermented cream in accordance with the participation of bacterial preparations "Iproovit KVM-C1" and "Iproovit KVM-C2" (Fig. 4a,b Fixed small amounts of diacetyl in sour-cream butter could be explained by a decrease in the biological activity of dairy raw materials, which adversely affects the development of fermented microflora.Weak synthesis of diacetyl is also associated with the negative effect of the highest amount of yeast in the winter [7].So, fermented cream with bacterial preparations up to 50ºT, 60ºT, 70ºT during the summer period contributed to a high content of diacetyl in the acidic oil by 14.0-17.0%,22.7-26.9%and 15.7-17.3%compared to products made from winter raw materials. Analysis of volatile organic acids showed that their content depended more on the level of fermentation of cream than on technological regimes of ripening and seasonality of raw materials.Thus, the amount of these compounds increased by factor of 2.0-2.7 with an increase in the acidity of the cream, whereas prod-ucts made from cream in the summer season had only 1.1-1.2times more acids (Fig. 4b).
Thus, by adjusting the fermentation of the cream it is possible to adjust the aromatic properties of the target product.
The results of the study of the physicochemical indices of experimental samples of sour-cream butter produced from cream under different temperature regimes and fermenting to different titrable acidity are presented in Table .1/ The degree of fermentation affected the acidity of the plasma of butter, milk fat, and sensorial characteristics of the product.The increase in the degree of cream fermenting helped to increase the acidity of the plasma and the content of dry skim milk residue in butter.Indirect evidence of the high activity of the starter microflora can be a significant increase in titrable acidity of the plasma.Lactic acid, which is formed during maturation, also affects the stability of the butter during its storage.Therefore, these samples of sour-cream butter have been investigated immediately after manufacturing and after 20 days of storage at a temperature (5±1)ºС.
Investigation of the peroxide value during the storage of products, as an indicator of the deterioration of milk fat, suggests that all analyzed samples conventionally belonged to the category "fresh".However, the change in the peroxide value of milk fat is indicative of more intensive oxidizing processes of butter produced from sour cream with an acidity of 70ºT.
Thus, fermenting of cream with bacterial preparations "Iplovit KVM-C1" and "Iprovit KVM-C2" to the plasma acidity of 60ºT ensures the formation of the desired flavor and aroma of sour-cream butter.
Obviously, the oxidation processes depend on the degree of cream fermenting and confirm the appropriateness of moderate fermenting of the cream for the manufacture of sour-cream butter.Therefore, the regulation of the process of squeezing cream is of great practical importance in the production of high quality of sour-cream butter.
The tasting of experimental butter samples showed that the butter obtained by cream whipping with acidity of 60ºT (sample №2) was characterized by the expressed sour-milk taste and aroma, for which it received the highest amount of points for taste -9 points for the first and 20 days of storage (from 10 possible).Product №3 had a unsufficiently aroma, and during the storage of butter appeared too sour taste.The rating of 8 points at the beginning of storage decreased to 5 points in 20 days.Product № 1 was marked by unexpressed taste and aroma on the first day after the whipping (8 points), and with the expressed sour-milk taste and aroma for 20 days, this product received 9 points.
Fermentating of cream with bacterial preparations "Iprovit KVM-C1" and "Iprovit KVM-C2" to the plasma acidity of 60ºT ensures the formation of the desired flavor and aroma of sour-cream butter.

Conclusion
New bacterial preparations are adapted to stepped ripening modes of cream, which can accumulate enough of the taste-aromatic components to form a flavorful bouquet of sour-cream butter.Due to the regulation of the process whipping cream on the physical and chemical parameters, it is possible to control the process of aroma formation in sour-cream butter.In order to maintain the stability of the sour-cream butter during storage, the optimum value of the acidity of the plasma of the cream before churning is 60ºT.The fermenting of cream to acidity of 70ºT can be used in the production of butter intended for quick sale.
to a radical change in temperature.After 3 hours of fermentation, a gradual decrease in active acidity was noted, and for 14 hours of fermentation of cream the value was 5.70-5.64units.pH.Continuation of fermentation of cream to 18 hours led to a slight decrease in pHby another 0.35 units, and by 21-22 hours.this figure reached 5.15-5.20 units.

Fig. 4 .
Content of flavoring in cultured butter for the winter and summer cream ripening: a) diacetyl; b) volatile organic acids