Prof. S. V. LEBEDEV and V. V. TIKHOMIROV

SOLDERING BY MEANS OF A FROZEN MERCURY JOINT

TOMSK

Prof. S. V. Lebedev and V. V. Tikhomirov.

Thawing Frozen Beet Cossettes with Steam

In the prospects for the development of the Siberian sugar industry, in connection with the distinctive climatic conditions and, in particular, with the prolonged stable winter without thaws, one of the characteristic and essential points is the possibility of long-term storage of beets in a frozen state. In connection with this, the question arises of the necessity of thawing the beets before slicing. Taking into account the possibility that beets may arrive at the plant at a low temperature, in certain periods reaching as much as 30° and 40° C below zero, and bearing in mind that thawing beets in diffusers is associated with a considerable expenditure of heat, sharply disrupting the usual heat regime of diffusion—in the present case the question is raised of preliminary thawing of the cossettes. For a number of reasons, it would be technically expedient to carry out this question by scalding beet cossettes during their movement between the slicer and the diffuser; at the same time, the question naturally arises of how easily and quickly this thawing can be carried out. On the other hand, this same assumption places before us the question of those changes which, under these conditions, may be caused both in the physical properties of the cossettes and in the chemical composition of the juice obtained from them.

This question inevitably arises in connection with the direct action of steam, i.e., of high temperature, on beet cossettes, which may have greater or lesser significance for sugar production as a whole. The very possibility of applying such a method of thawing frozen cossettes must depend, to a certain extent, on the degree of these changes. In connection with this, the necessity arises to clarify the various phenomena occurring during scalding, and, in addition, the physical and mechanical properties of the scalded cossettes, as well as the chemical changes in the juice obtained from such cossettes, if such changes take place.

For the experiments, Altai beets were used, delivered to Tomsk at the end of October. The beets were received in a completely frozen condition and were subsequently stored in a covered board shed, which readily admitted changes in the outside temperature.

The roots were of ordinary shape, white in section, and showed no darkening or, in general, phenomena that might indicate freezing of the beets or their thawing. The composition of the beets is characterized by the following data:

Table No. 1

The composition of the normal juice and the digestion were determined when the beets arrived at the laboratory. The data concerning nitrogen represent the averages of determinations made at different times in the course of carrying out the present work.

The experiments began in January. The lot of beets intended for the experiments was divided into 2 unequal parts. The smaller portion was kept in the cold chamber of the cold laboratory described below, which during \(1 \tfrac{1}{2}\) months of storage had an average temperature of about \(5—10^\circ\text{C}\) below zero. The remaining, larger part of the beets, with which the experimental investigation on the subject of the present work was carried out, was stored in the aforementioned shed in the open air at lower temperatures. The necessity of placing part of the beets in the cold chamber was caused by the peculiarity of the climatic conditions of Western Siberia. In winter, sharp fluctuations of the outside-air temperature are possible not only over the course of several days, but even within a day, which could have affected the maintenance of uniform temperature conditions over a prolonged series of experiments. Therefore the use, for storing frozen beets, of the special cold laboratory arranged at the Department of Nutrient Substances of the Siberian Technological Institute proved very successful. The latter is a stone annex deeply sunk into the ground, with double walls, communicating with the premises of the laboratory of nutrient substances. The outer walls of the annex are brick, with air channels inside, and the inner walls are concrete. The whole room is divided into two chambers. In the first chamber, which in what follows we shall call the cold laboratory, the air temperature during the winter months from December to March averaged about minus \(5^\circ\text{C}\), while in the second chamber, which we shall call the refrigerating room, during the same period it was about minus \(8^\circ\text{C}\). In both these rooms the temperature remained fairly stable within known limits over time, but over the winter as a whole the temperature nevertheless gradually changed. In connection with the fact that one of the essential points in elucidating the phenomenon of thawing of cossettes by the method of scalding with steam was the question of changes in the beets during storage over the course of the experiments, it seemed of interest to conduct

a series of comparative observations with beets under different storage conditions. Since in this case there was a room with a considerably higher temperature than the temperature of the outside air, it proved possible to broaden still further the amplitude of fluctuations in storage temperature. For the stated purpose, three samples were selected from the entire batch of beets, 40 roots each, and placed in sacks. In view of the possible sharp difference of individual beets from one another, all these samples, both by weight and by the external similarity of the roots included in them, were selected to be as nearly identical as possible.

One of the samples, weighing 16,000 grams, was stored continuously in the outside air; another, weighing 14,820 g, in the cold laboratory with temperature fluctuations from −2°C to −6°C; and the third, weighing 16,270 g, was transferred alternately every 5 days from the outside air to the cold laboratory and back. In the latter case the beets experienced fluctuations of the outside temperature with an amplitude from 2–6°C below zero to 10–34°C below zero. All samples were again weighed simultaneously, with an accuracy of 0.05%, every 5 days. The observations were carried out from January 15 to March 15. After March 15 the samples were transferred to a refrigerated room and then examined. Drawing 1 shows the changes in the mean and minimum daily temperature of the outside air and of the beet-storage facilities, by five-day periods from October 1 to April 1, according to the data of the meteorological station. (See Drawing 1).

The course of the curves indicates very sharp fluctuations in the temperatures of the outside air and the relative constancy of the temperatures of both cold rooms. Sharp fluctuations in the temperature of the outside air, however, are gradually transmitted also to the cold room, being reflected somewhat more in the cold room and less in the cold laboratory. The temperature of the outside air over the 2 months of observations averaged about minus 20°C, fluctuating from −3.5 to −34°C. The temperature of the cold laboratory fluctuated from −2.5°C to −7.7°C, averaging −8.5° over the observation period. Although the temperature of the cold laboratory seemed to preclude the possibility of thawing, nevertheless, 25 days after the beet samples had been placed there, it was noticed that the tail part of the beets had become considerably softer than the rest of the root mass. Gradually the softening became more distinct and, finally, the tail part proved, to the touch and in appearance, to have completely thawed; when it was cut, unfrozen juice appeared from it. Such softening was also found in the peripheral layers of the root. At the same time the weight of the sample also decreased. At the beginning of March the same phenomena, though less clearly expressed, could be observed in the transferred sample as well.

The change in the weight of the samples is shown by curves; along the abscissa of the diagram time is plotted (see Drawing 1), and along the ordinate axis the weight is laid off in % of the initial weight at the time of storage.

From these data of the drawing, presented below Table No. 2, it is evident that beets kept in the outside air experienced almost no loss in weight, which in the final count amounts to only 0.74% of the initial weight. The greatest loss in weight occurred in the beets stored in the cold laboratory (about 8%); the weight loss of the transferred sample occupies a certain intermediate position (about 5%).

During the examination of the samples, carried out at the end of March, the following was found. The peripheral layers of the beets stored in the cold laboratory, as had already been observed during storage, had thawed; the thawed

the layers had blackened, had become friable, while the frozen middle remained unchanged. These changes occurred in all three storage cases, but to differing degrees. When roots stored under one or another set of conditions were cut open, extremely characteristic sections were observed with respect to the dark coloration of the peripheral part of the root and its position relative to the unfrozen light-colored part. At the same time, an unequal quantitative ratio of this blackened, unfrozen part to the remaining frozen part was revealed. This is quite clearly expressed by the attached photographs. The latter represent typical pictures of numerous sectioned roots for each of the storage cases. The photographs for each case are presented for each root by one longitudinal and transverse sections of the same root.

Photographs Nos. 1—3 refer to the case of storage in the open air. Photographs Nos. 4—6 refer to the case of storage exclusively in the cold laboratory. Photographs Nos. 7—9 refer to the case of repeated transfer and holding for 5 days in the open air and then in the cold laboratory.

Table No. 2 contains a summary of the data from the examination of the samples.

Table No. 2

Without entering in the present work into a detailed analysis of the essence and causes of the phenomena ascertained, we may, to a certain extent, arrive at a general conclusion regarding the evaluation of each of these methods of storage. It turns out that the best method was storage directly in the open air. At the same time, this conclusion indicates that, in the experiments on treatment with steam of beet stored in the open air carried out on the subject of this work, the best possibility was guaranteed for the uniformity and invariability of the material used over a long period of experiments. For the experiments, beet shavings were used, obtained on the ordinary knife of a factory beet slicer installed in a knife frame. The essence of the wo-

The work required that, before scalding, the beet should not thaw in the slightest; therefore all measures were taken to guard it against thawing during cleaning and cutting. To this end all preparatory work was carried out in the above-mentioned cold laboratory, with an average temperature close to minus \(1^\circ\)C. The usual washing off of dirt was replaced by cleaning with a dry brush. In isolated cases requiring unconditional cleaning, when at the same time thawing of the thin surface layer did not run counter to the aims of the experiment, the beet was quickly washed with ice water in the same cold room. The beet was cut by hand on the indicated knife of the beet slicer, while double woolen gloves were put on the hands. The cossettes were kept in hermetic jars in the open air. The weighing was carried out in the cold laboratory; the scales, the apparatus in which the cossettes were scalded, and all necessary vessels were kept there as well. The cossettes were white, of normal shape, \(4\)–\(5\) mm thick, and usually contained no pulp. Only in severe frosts of about \(-30\), \(-40^\circ\)C, owing to the hardening of beet brought directly from the frost, was it difficult to cut; thin, short, and torn cossettes were obtained.

In such cases the beet was brought into the cellar beforehand, where it “recovered” somewhat, after which the cutting proceeded satisfactorily. The cossettes were carried out into the open air. For approximately one day the cossettes kept well in the frost, without blackening or changing. When stored for more than one day, individual pieces of cossette were observed to freeze to one another to such an extent that, when a weighed portion was taken, the cossettes broke. Therefore cossettes were prepared for \(1\)–\(2\) days. Frozen cossettes in general proved to be very brittle; the brittleness depends on the temperature, increasing as the temperature is lowered. In observing the cutting process it was established that the cossettes most correct in size and at the same time least brittle were obtained when the beet was cut in the longitudinal direction, i.e. in the direction of the distribution of the vascular-fibrous bundles along the length of the cossette, which also accounted for its relative strength; therefore, subsequently, the roots were cut exclusively in the longitudinal direction.

As the source of steam, a small steam boiler was used, with the necessary apparatus and piping with appropriate insulation. To the end of the pipeline, at a right angle, a nozzle was vertically attached in the form of a brass tube \(16\) mm in diameter and about \(250\) mm long. Along \(100\) mm of the length of the nozzle, from its lower closed end, \(100\) holes about \(0.5\) mm in diameter were uniformly arranged in a staggered pattern. The steam boiler did not have sufficient steam capacity; therefore the pressure in the boiler remained constant only for several seconds from the moment the steam was admitted. For scalding, a special apparatus was constructed, consisting of a cylindrical tin vessel \(175\) mm high and \(100\) mm in diameter, with a perforated false bottom. In the center a cylindrical fine mesh was fastened, \(35\) mm in diameter and \(14.5\) mm high. The space inside the mesh, not filled with beet, was intended for insertion of the steam nozzle, which reached to the very bottom. To prevent the carrying away by steam of spray and the sugar losses associated with this, the vessel was closed with two brass meshes fastened together at a distance of \(2\) cm from one another, with an opening for the nozzle. With the use of the meshes, the losses of sugar, detected by the alpha-naphthol reaction in the condensate of the outgoing steam, were eliminated.

The scalding experiments themselves were carried out as follows. The required pressure was established in the boiler. Before scalding, the steam line and the nozzle were warmed up in order to eliminate condensation during scalding. The apparatus, charged in the cold laboratory and having assumed the temperature of the outside air, with a sample of 136.5 g, was quickly brought to the steam nozzle, into which steam was then immediately admitted.

With sufficient warming of the steam line, the moment at which steam was admitted coincided with the moment of its appearance in the apparatus. All manipulations, because of the danger of preliminary thawing, were carried out with the greatest possible speed.

Individual experiments differed in the duration of scalding and in the initial temperature of the frozen cossettes. Orienting experiments in the direction of varying the temperature of the warming steam showed that experiments of this kind, with the limited capacity of the laboratory steam boiler and with scalding by live steam, could not be carried out under proper conditions.

Initially, a series of experiments was set up to clarify the external effect observed when frozen cossettes were scalded under various conditions. The scalded cossettes were quickly removed from the vessel and examined. Observing the scalding process as it developed over time, it was possible to establish the following phenomena.

1) The cossettes, being strongly saturated with moisture, appear wet in the first moments after thawing.

2) Associated with the thawing of the cossettes is the appearance at the bottom of the vessel of a turbid, faintly colored, sugar-containing liquid, which we shall call “liquid waste.”

3) Further scalding rapidly warms the cossettes; in this process the cossettes become drier.

4) Finally, under prolonged action of steam, for more than 30 seconds, the cossettes obtained have lost their elasticity and strength, are slippery to the touch, and when kneaded are comparatively easily converted into a shapeless mass. In addition to all this, it was observed that well-warmed cossettes do not blacken in air, remaining white.

Thawed but only weakly warmed cossettes blacken rapidly.

The series of external signs enumerated above distinguishes three principal moments in the development of the scalding process:

a) the moment of complete thawing—3–5 seconds with full access of steam. It is characterized by cossettes that are wet after thawing, that blacken rapidly in air, and by the runoff of liquid waste;

b) the moment of warming of the cossettes—10–20 seconds; they are relatively dry, blacken slowly in air, and the runoff of liquid waste ceases;

c) the moment of “over-scalding”—more than 20 seconds; the cossettes are slippery to the touch, comparatively easily converted into a shapeless mass, and do not blacken in air.

It follows from what has been said that scalding of cossettes for the purpose of thawing must be limited to definite time intervals. The moments of warming, and still more of over-scalding, appear to be moments that threaten the fundamental properties of the beet. Therefore, for the study of the scalding process it is essential to establish the moment of thawing, as the one most corresponding to the aims set. Establishing this moment was one of the immediate tasks of the present investigation. The method for studying the scalded cossettes was outlined separately—

preliminary orienting experiments. The means for recognizing and establishing individual moments of scalding were, above all, the external signs of the scalded chips, and also the quantity of liquid waste running off. The scalded chips are immediately examined by touch, and the resulting liquid waste is separated on a sieve funnel and weighed on technical scales. In the appended table, individual moments of the scalding process are noted; the table combines the results of three series of experiments; each series in this case, and subsequently, combines experiments carried out in one day at a definite temperature of the outside air and, consequently, at the corresponding temperature of the frozen chips.

Table No. 3

From the data of the table the following conclusions follow:

1. The process of thawing frozen chips is a short-term process and is expressed in a few seconds, fluctuating from 30 to 10 seconds. At the same time, no appreciable influence of the initial temperature of the frozen chips is noticeable.

2. With an increase in the steam pressure in the boiler, the time required for thawing decreases, which is evident from a comparison of the experiments of series I and III.

1. The quantity of liquid waste formed during scalding is limited by a certain value. For the given beets and the conditions of the given experiments, the ratio of the weight of the liquid waste to the weight of the beets taken is a constant quantity, on average from several determinations equal to 23–24%.

Observing the external appearance of the scalded cossettes, it could be noted that the ice present in the frozen beet in the form of rather large aggregates melts under the influence of scalding; the resulting water drains off, and the cossettes acquire a sort of pitted appearance. As already indicated, in the first moments of scalding the cossettes are as if more saturated with water, and then become drier. In connection with this, the question arose of the change in the weight of the cossettes during scalding, depending on the duration of the latter. To clarify this, a series of experiments was set up. The scalded and cooled cossettes, after careful removal from the vessel, are weighed with an accuracy of up to 0 g. Owing to the presence of a false bottom, complete separation of the draining liquid waste from the scalded cossettes is achieved.

The results of the experiments are presented in Table No. 4.
Observations were carried out in 2–3 parallel trials.

Table No. 4

The results of the experiments lead to the following conclusions:

1. The weight of frozen cossettes changes in the process of scalding, increasing in the first moments of thawing and decreasing thereafter.

2. The decrease in weight over time proceeds unevenly: with an increase in the duration of scalding, the decrease in weight falls, reaching a certain limit.

3. The limit of loss in weight for the given beets and the conditions of the given experiments is about 10% of their initial weight.

It seemed of interest to elucidate the phenomenon of the change in the weight of frozen cossettes by comparing it with a similar scalding of cossettes from unfrozen beets. As a result of several experiments carried out, it proved that the decrease in the weight of the latter during scalding is insignificant. Thus, for example, unfrozen cossettes, scalded for 45 seconds under the same experimental conditions as the frozen ones, lost no more than 1% of their weight, i.e., 10 times less than the frozen cossettes.

These experiments shed light on the question of the origin of the liquid waste that drains off, suggesting that the liquid waste is, on the one hand, the result of steam condensation, and, on the other hand, the result of the melting of ice separated out in frozen beets in the form of rather large aggregates.

As a consequence, the experiments performed raise certain questions connected with the course of the diffusion process in the case of scalded frozen cossettes. As is known, the formation of ice during the freezing of beets occurs outside the cells. Imbibition water and the water of the cell sap are drawn into the intercellular spaces¹), which increases the concentration of the cell sap. Therefore, after scalding and the loss of ice, beets must constitute an unusual material for diffusion. Owing to this, certain shifts in the conditions of the diffusion processes are possible. On the one hand, as a result of the change in structure due to the melting out of ice, the normal resistance of cossettes to matting is disturbed, which has also been established by factory practice; on the other hand, the degree of loading of the diffusers changes.

Since the resulting liquid waste is, by its origin, connected with the substance of the beet cossettes, the question arises as to its composition, concentration, and, in connection with this, also the place that this new product may occupy in the course of production. Therefore, further experiments were directed toward determining the properties and composition of the liquid waste. The liquid waste is a turbid liquid containing suspended particles, slightly yellowish in color, outwardly similar to the juice from the last diffusers. In addition to scraps of pulp, the contents of ruptured cells, etc., it contains a considerable quantity of external impurities washed from the cossettes by steam.

After weighing the apparatus, the liquid waste was separated from the cossettes and transferred to a measuring flask. In the resulting waste, the percentage content of dry substances and the amount of sugar were determined. In view of the small quantity of liquid, the possibility of using an areometer was excluded. Therefore, to determine the percentage content of dry substances, a refractometer was used (Abbe and Eintauch-refraktometer Zeiss’a), requiring only 1–2 drops of liquid. Since this quantity had almost no effect on the entire mass of liquid waste, the sugar content in it was determined in the same sample by direct polarization, filling this flask to the mark, after preliminary clarification with lead acetate.

Knowing the percentage sugar content in the frozen beets, its content in the wastes, and also the quantity of liquid waste, it is easy to determine what percentage of sugar by weight from that in the beets passes into the liquid waste. In exactly the same way, one can calculate the quantity of dry substances of the cell sap, in percent, that passes into the liquid waste by weight of the dry substances of the beet cell sap.

These data provide orientation and make it possible to approach the question

¹) Zuev, “Encyclopedia,” vol. 1, p. 65.

on the degree of rupture of the mass of the root that has undergone freezing. As is known, the number of opened cells on the beet cutter when slicing beet can be determined and depends on the thickness of the chips and the system of the knife. Thus, if certain conditions are present for one and the other in this respect, it is possible to determine the number of opened cells at the expense of the beet.

By comparing this value with the data obtained for frozen beet on dry substances, the amount of which will be relatively higher, one can form an idea of the number of cells opened in the frozen beet, i.e., of the presence of ruptures.

The results of the experiments with respect to the composition of the waste are presented in Table No. 5.

Table No. 5

On the basis of the experiments carried out, the following conclusions may be drawn:

1. The process of scalding cossettes is associated with the accumulation, in the liquid waste, of elements of the beet cell sap.

2. The concentration of dry substances and the composition of the liquid waste, as the scalding process develops, change little after settling, remaining constant within the accuracy of the experimental determinations.

3. The absolute content of dry substances in the liquid waste may increase until the condensation process ceases. The process of extracting elements of the cell sap is limited by a certain boundary; for the given beet no more than 9% of the weight of the dry substances (or sugar) of the cell sap can pass over.

The purity of the liquid waste fluctuates within the range 81.9–84.9%, averaging 82.9%.

As can be seen from the numerical data, the density of the liquid waste corresponds approximately to 8–9° Brix.

Such a density of the waste, with a relatively high purity, indicates where this auxiliary product may be directed in the production scheme. Taking its characteristics into account, and the inexpediency of loading diffusion with it, one may assume that it should be directed to the measuring tanks. At the same time there are grounds to suppose that the figures for the amount of liquid waste and its concentration in our laboratory setting differ somewhat from those that would occur in production. Under the conditions of our experiments, a considerable share of the liquid waste consists of condensate produced by heating the metallic apparatus, not counting other causes that induce condensation. Obviously, in the industrial implementation of the process this auxiliary condensation may be reduced to a minimum, owing to the presence of certain technical possibilities and the scale of production (the principle of continuity, insulating the apparatus, etc.). Under the conditions of the present experiments it is difficult to establish the quantitative aspect of condensation and to separate it from the melting of cossette ice associated with it; but with respect to the quality of all the liquid waste obtained, certain propositions can be put forward.

Comparing the purity data for liquid wastes with the purity of normal beet juice (Table No. 1), we see that the numerical values of the purity are almost equal:

Average purity of normal juice . . . 83.0

Average purity of liquid wastes . . . 82.9

There is reason to suppose that the similarity of the purity values of these products is not accidental.

The results of the experiments show that the dry substances of the cell sap are released into the liquid waste only until condensation ceases. Since the period of release is limited to only 10–20 seconds, it is difficult to think that, in the present case, alongside the processes of simple mechanical washing out from opened cells, diffusion processes from neighboring intact cells could also have time to develop simultaneously. It is more correct to connect the composition and degree of release only with mechanical washing out. This also makes clear the coincidence of the purity values of the liquid waste and the numerical value of the purity of normal juice, i.e., the liquid waste is nothing other than diluted normal juice.

Comparing the results of the analyses with the propositions stated above concerning the relation between the number of opened cells and the cutting of the beet and its ruptures during freezing, the following may be noted.

If fresh cossettes, with a thickness of 4 mm, have about 2.5% of cells opened by rupture¹, then in this case no more than 2.5% of sugar, by weight of the beet sugar, could have been washed out of such cells.

Although our frozen cossettes have exactly the same thickness, nevertheless, as we have seen, by scalding about 8–9% of sugar, by weight of the sugar in the cossettes, is washed out of them, that is, 3.2–3.6 times more than would be expected by calculation for unfrozen beet. This confirms the assumptions we expressed earlier.

Further experiments were directed toward elucidating changes in the chemical composition of the beet. Since the process of thawing frozen cossettes requires a comparatively short interval of time, 3–5 seconds, the question of chemical changes would seem to lose its significance, since it would be difficult to assume substantial changes in the chemical composition of the beet in so short a period. However, scalding must be regarded as a process whose technical formulation under production conditions is still not sufficiently clear.

In the present case, the magnitude of the mass of beet cossettes that will have to be heated with steam will be of essential importance. If chemical changes under the influence of excessive heating in the inner layers of the cossettes are unlikely, then their possibility in the outer layers, directly subjected to the direct action of steam, is entirely admissible. Therefore, alongside the question of the physical and mechanical phenomena associated with scalding, the question of possible chemical changes must also be posed. In view of the fact that in the future the technical formulation of scalding under production conditions is to be carried out, the scope of the experiments, especially with respect to the duration of scalding, must be somewhat expanded. All chemical changes possible during scalding will evidently be the result of the action of the temperature of the steam entering the air, i.e., having about 100°C. The influence of steam of such a temperature on the various constituent parts of both the cell sap and the beet pulp has scarcely yet been touched upon. The ordinary action of high temperature on the various substances composing the beet has been studied on solutions of definite concentration either under conditions close to those of the factory or in a definite artificially created setting. In our experiments the action of steam is directed immediately upon the entire complex assemblage of chemical-biological and morphological elements of the cellular tissue as a whole, moreover frozen under conditions entirely unusual for sugar production. This is the chief distinction of our experiments.

In the present work only some of the possible changes are considered with respect to the most important elements of the beet composition, namely: the question of changes in sugar and nitrogenous substances. The degree of change was assessed by examining the diffusion juices obtained. Since we were interested in the final effect of digestion not only with respect to sugar, but also to nonsugars, digestion was carried out without treatment with lead acetate.

Several preliminary experiments made it possible to ascertain that digestion of whole chips at \(85^\circ\) C proceeds just as completely as digestion of special digestion mash. This made it possible to simplify the procedure, without subjecting the chips to additional grinding.

Appropriate flasks were taken, graduated to 1053.2 cm\(^3\), which, with a weighed portion of 136.5 g, corresponded to the normal dilution. The general procedure of digestion was as follows. After scalding, the chips, together with the liquid waste, were quantitatively transferred into the digestion flask, filled to \(3/4\) with water, and digested for 60 minutes in a water bath. After cooling and bringing to the mark, the digestion juice was immediately separated from the chips and examined. The first question posed was that of changes in direct polarization and in the purity of the digestion juice, depending on the different duration of scalding of the chips. Since for each series of experiments no more than 4–5 roots were cut up, individual experiments could differ in their results even when the experimental conditions were identical. In this connection, with each digestion of scalded chips, unscalded chips were digested in parallel. The % of dry substances of the juice was determined with an Eintauch-refraktometer, according to the directions of Stanek¹. The digestion juice is first refractometrized, and then, after treatment with lead acetate, polarized. From the tables, according to the refractometer reading, the % of dry substances is found, and from the polarization—the % of sugar in 100 cm\(^3\) of juice, whence the purity is obtained.

The results of digestion at a temperature of \(85^\circ\) C and a digestion duration of 60 minutes are presented in the following table:

Table No. 6

According to the results of the experiments, it is evident that scalding does not cause noticeable changes in the final result of digestion either with respect to the sugar content or with respect to the purity of the juices. In experiments with deliberately prolonged scalding time, no destruction of sugar was detected either.

The next question posed was that of the influence of scalding on the passage of total and protein nitrogen into the digestion juices. Judging from experiments with the scalding of unfrozen beet,^1 one may expect from scalding a certain juice-purifying effect for juice extraction in the sense of coagulation of proteins. In view of the fact that, in establishing this fact, it was necessary to exclude the influence of the digestion temperature, acting in the same direction, the scalded cossettes, after cooling, are digested at 45°C, at which, as is generally assumed, any possibility of coagulation of protein substances will be almost excluded. Preliminary experiments showed the possibility of digesting frozen beet at this temperature. The table presented shows the influence of scalding on the passage of protein and total nitrogen into the juices.

Table No. 7

From the numerical data of this table it is evident that scalding reduces the passage of total and protein nitrogen into the digestion juices. Thus, a definite juice-purifying effect is associated with scalding.

In order to determine the completeness of digestion at low temperatures and to establish the optimal conditions with respect to the possibility of digestion at various lowered temperatures, a series of experiments was set up. The basis for this was the assumption that in the cells of frozen beet, owing to prolonged rolling in fro-

^1 Zuev, Encyclopedia, vol. I, p. 307.

...frozen state, such profound changes have already occurred in the plasma that heating the cossettes becomes superfluous. The results of the experiments are presented in the table. Frozen, unscalded cossettes are digested.

Table No. 8

Thus, taking into account a certain nonuniformity of the individual experiments, it may be asserted that temperatures of 65°C, and even of 45°C, are quite sufficient for complete digestion of frozen cossettes. In connection with the finally established possibility of digestion at 45°, a series of digestions was specially carried out at this temperature. In this case a special aim was pursued—to trace how scalding is reflected in the final result with respect to the extraction of sugar.

In order that the possible effect of scalding in this respect might be revealed more distinctly, the limits of the experiments, in terms of the duration of scalding, were extended still further.

Table No. 9

Assessing the significance of digesting scalded and unscalded chips, we see that scalding is not reflected in any noticeable way in the final result of digestion, within the limits of accuracy of our experiments. Summarizing the conclusions obtained as a result of all experiments on the digestion of frozen scalded and unscalded chips, we arrive at the following general conclusion. Frozen beet is a material that, thanks to the prolonged action of frost, is already so prepared for juice extraction that the need for heating in order to coagulate the plasma largely disappears. This circumstance at the same time opens up new possibilities with respect to the use of temperatures unusually low for the juice-extraction process.

Several exploratory experiments carried out in this direction show how freezing, and on the other hand scalding of fresh and unfrozen chips, is reflected in the digestion process. The experiments consisted in determining the development of the digestion process from frozen and unfrozen beet, scalded and unscalded, during digestion at \(45^\circ\text{C}\). Under parallel digestion conditions, the rates of extraction from scalded and unscalded chips were determined by taking successive samples of juice every 10 minutes. For greater clarity in identifying the individual numerical values expressing the extraction process, the dilution in digestion was higher than normal, in particular varying as follows: 200 g of chips to 400, to 500, and to 700 g of water.

Table No. 10

Data on the digestion process of frozen beet at \(45^\circ\text{C}\)

Extraction effect, in % of the final dry-substance content, with scalding

The individual experiments were carried out as follows. Both the scalded and the unscalded chips were brought to room temperature before digestion, then were poured with water at \(45^\circ\text{C}\) and placed in a bath at the same temperature. In all cases the chips were scalded for 45 sec. at 2.5 atm pressure. For investigation from the digestion liquid

1–2 drops were taken, which in practice did not affect the volume. The investigation was continued until several successive readings of the refractometer coincided. According to the refractometric refractive indices obtained, the percentage of dry substances in the solution was found from tables. The first experiments were performed with frozen beet, cut into cossettes in the open air. The three experiments cited below differed only in the dilution of the digestia. The results of the experiments are brought together in Table No. 10. As 100% extraction effect there was taken the final content of dry substances in the digestion liquid for scalded cossettes. Thus the numerical values of the extraction effect express the percentage ratio of the content of dry substances at each individual moment to the final content during the digestion of scalded cossettes.

The numerical data of the table can be more clearly expressed by the curves presented in drawing P. On the ordinate axis are plotted the values of the extraction effect. On the abscissa axis is time. (See curves Nos. 1, 2 and 3.) The table and the curves show that both scalded and unscalded cossettes of frozen beet hardly differ in the rate of extraction of dry substances. The digestion process develops very rapidly, ending 40–60 minutes from the start, despite the unusually low temperature. In order to reveal the specific significance of prolonged freezing in the dynamics of digestion, experiments were carried out with unfrozen beet. The conditions of scalding and digestion were as in the preceding case. Series XXIII of Table No. 11 shows the course of the process of extracting dry substances from fresh, both scalded and unscalded, cossettes; curve No. 4 (drawing II) depicts the course of the process.

Table No. 11

Data on the process of digestion of fresh and briefly frozen cossettes

Extraction effect in % of the final content of dry substances during scalding

The experiments of series XXIII revealed the following:

Digestion of unscalded cossettes of unfrozen beet at 45°C is difficult; it is manifested extremely weakly, develops very slowly, and after 8 hours is not fully completed. Scalding accelerates the rate of extraction; digestion develops, although slowly in comparison with frozen beet, but nevertheless can be brought to completion, requiring about 1½ hours for completion. For this purpose

to determine how freezing and short-term storage in the cold affect the digestion process, the halves of the roots remaining from the preceding experiments were frozen and kept at −5°C. The shavings obtained from this completely frozen beet, in appearance, resembled unfrozen shavings rather than frozen ones; in them there were noticeable neither ruptures nor distinct separation of ice. Digestion of these shavings is represented by series XXIV of the preceding table and shown by curve No. 5. From the data obtained it is evident that, in terms of the rate of the digestion process, briefly frozen beet occupies a certain intermediate position between unfrozen beet and beet clamped in the open air. Freezing of beet smooths out the difference in the rate of digestion of scalded and unscalded shavings.

CONCLUSIONS:

As a result of all the observations and experiments made on the question of the possibility of thawing frozen shavings with steam, the following conclusions may be drawn:

1. Complete thawing of frozen shavings when scalded with low-pressure steam is a short-term process, expressed in a few seconds.

2. The external properties of the shavings, their elasticity and appearance when scalded, do not change appreciably until the moment of their complete warming-through.

3. When scalded, the absolute weight of the shavings decreases because of the liquid run-off, amounting to about 10% of the weight of the shavings. The separation of the run-off ceases from the moment the shavings are warmed through.

4. The run-off is a yellowish liquid, not darkening, with a concentration of about 8° Brix. By its nature the liquid run-off is the contents of opened cells; its quality corresponds to the quality of normal juice.

5. Up to 8–9% of the sugar, reckoned on the weight of the sugar in the beet, passes into the liquid run-off.

6. No effect of scalding on the quality of digestion juices in the sense of sugar destruction is detected. The amount of protein and total nitrogen passing into the digestion juices is, in the case of scalded shavings, less than in the case of unscalded shavings.

7. Scalding, which changes the dynamics of digestion of fresh beet, has no effect on frozen beet clamped under Siberian conditions.

Tomsk.

Laboratory of the Technology
of Nutrient Substances.
Siberian Technological Institute.

Dynamics of the digestion process at 45°C
of frozen and unfrozen chips,
both defibered and not defibered

Curve No. 1.

Y-axis: % — for defibered chips.
Right-side label: frozen chips.
X-axis: 0, 20, 40, 60, 80, 100, 120 minutes.

Curve No. 2.

Y-axis: % — content of dry substance.
Right-side label: frozen chips.
X-axis: 0, 20, 40, 60, 80, 100, 120 minutes.

Curve No. 3.

Y-axis: % — in the final juice of dry substance.
Right-side label: frozen chips.
X-axis: 0, 20, 40, 60, 80, 100, 120 minutes.

Curve No. 4.

Y-axis: % — extraction effect of dry substances.
Right-side label: unfrozen chips.
X-axis: 0, 20, 40, 60, 80, 100, 120 minutes.

Curve No. 5.

Y-axis: % — extraction effect.
Right-side label: freshly frozen chips.
X-axis: 0, 20, 40, 60, 80, 100, 120 minutes.

Legend:

— defibered chips.
- - - - - not defibered chips.

Fig. 12. Course of the meteorological elements during the 1930/31 vegetation period

\((T^\circ)\), degrees

October — November — December — January — February — March

I — II — III

Legend:

— Mean five-day temperatures of the outside air
– – – Mean minimum temperatures of the outside air
– · – · – Mean temperature of the cold laboratory
– ·· – ·· – Mean temperature of the cold room

Inset:

Loss of film weight during the 3rd five-day period of June

Legend for inset:

— Light storage in the outside air
– – – Light storage in the cold laboratory
– · – · – Light storage in the cold room
– ·· – ·· – Without turning over

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4

5

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9

1. Zeitschr. f. Zuck. in B. 1911. S. 375. ↩↩