May, 1924
I N D U S T R I A L A N D ENGINEERING CHEiMISTRY
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Constructive Chemistry in Relation t o Confectionery Manufacture’ By H.S. Paine CARBOHYDRATE LABORATORY,
BUREAU OF
C m M I S T R Y , WASHINOTON,
D.c.
The logical basis for improvement in confectionery manufacture Considering all types of ONFECTIO N E R Y confectionsl the mixing of manufacture is an is exact chemical and physical knowledge. For years the craft secrets of this industry have been developed empirically, jealously sucrosei corn sirup, and inold art which, as is guarded as in the days of the alchemist, and handed down from vert sugar1 with and withthe case with many indusout admixture of crystalline tries, has been developed generation to generation by the apprentice system. empirically and largely by I t is the purpose of this article to discuss briefly the application and colloidal materials and a s s 0 c i a t e d with heating of chemistry and physics to the constructive improvement and rule-of-thumb methods, but nevertheless effectively standardization of methods of manufacture. B y way of example, within a wide temperature the commercial process for manufacturing fondant types of candy is range (to a maximum as It8 Craft Secrets have Until described from the scientific standpoint, outlining the considerations high 8s 350” F.), results in C o m p a r a t i v e l y recently which have led to the successful use of the enzyme invertase on an the Production of an amazbeen jealously guarded and h a n d e d down from one extensive scale by some of the largest confectionery manufacturers. ing array of physical states and conditions, including generation to another by the a p p r e n t i c e s y s t e m . saturation, supersaturation, Chemistry has contributed very little in a direct manner to adsorption, gels, syneresis, emulsions, supercooled and solid the development and progress of this industry, although solutions, etc., etc. Even with laboratory facilities, it would conditions during recent years have changed rapidly and now be difficult to produce a greater variety than is found in actual forecast its development on a more scientific basis. Man- commercial practice. ufacture of confectionery is one of the major industries in the PREPARATION AND PROPERTIES OF FONDANT United States from the standpoint of annual value of products, and merits constructive chemical study. Walter C. Hughes, Fondant is prepared from a sirup composed of sucrose and secretary of the National Confectioners’ Association, in a commercial glucose in variable proportion by boiling to 232 Ocommunication to the writer, states that approximately 750,- 244’ F., then quickly cooling to approximately 90” F. and 000 toris of candy were manufactured in this country in 1923 agitating in a beater or similar device to produce rapid crysand that in round numbers 390,000 tons of sucrose, including tallization of sucrose, conditions being so controlled as to both cane and beet sugar, were used. He states that the cause formation of minute crystals which are practically total value of candy sold to consumers during 1922 was ap- impalpable to the tongue. The quality of the fondant is proximately one billion dollars and the total number of em- determined] among other factors, by the proportion of suployees in the industry, including factories and the wholesale crose used and by the smoothness of consistency as determined and retail trade, was approximately 250,000. From the stand- by the size of the sucrose crystals. The manufacture of point of value of products, the candy industry was ranked as high-quality fondant, aside from influence of grade of rawmatwenty-second among 353 industries listed in the Census of terials, is essentially a problem of control of water content and Manufactures of 1921. size of the sucrose crystals as determined by such factors as Not only is there a dearth of chemical literature pertaining temperature and degree of agitation during “creaming” directly to confectionery manufacture, but, so far as the writer (crystallization) and presence of invert sugar and colloids has been able to ascertain, there has been little interpretation which influence rate of crystallization and size of the crystals. from the standpoint of chemical and physical theories of the I n certain types of candy, materials such as egg albumin may procedures involved.in candy manufacture, the reasons for the be added before creaming, and will, therefore, influence various precautions observed, and the influence of variation in crystal size. I n most confections, however, such materials character of materials. The rule-of-thumb directions and de- are added after the fondant has been prepared. The skilled tails given in the multitude of recipe and formula books on candy maker is very adept in the control of these factors. candy manufacture which are now extant are seemingly very His skill with regard to control of crystallization is similar t o complicated and quite confusing to the uninitiated. A study that of the expert sugar boiler in a sugar factory or refinery, of the application of certain chemical and physical principles with the important difference that, whereas the latter starts is, however, sufficient to clarify this maze of details. I n with a clarified sirup obtained directly from sugar cane or considering the mass of data and information acquired beets and reduces the “purity” and crystallizes the sugar in through many years of empirical experimentation on the part two or three stages with intervening and final centrifugal of persons rather poorly informed regarding the basic the- separation of mother liquor (molasses), the former employs a ories underlying the phenomena involved, one is nevertheless sirup prepared from white sugar (and corn sirup) and effects impressed with the results that have been obtained. crystallization of sucrose in one stage without removing any The principles involved in a chemical and physical inter- mother liquor. pretation of some of the most typical aspects of candy manFondant, while apparently a solid, will therefore be recogufacturing processes applying to the fondant types of confec- nized as possessing an interior liquid phase consisting of tion are primarily those of colloid chemistry, the theories mother sirup from which the minute sucrose crystals have been pertaining to viscosity and plasticity, and the somewhat derived. This sirup is present as a more or less continheterogeneous subject matter which may, for sake of brevity, uous film enveloping and separating the multitude of indibe termed “sugar chemistry.” vidual, microscopic sucrose crystals. The physical structure of fondant may approach a condition of colloidal dimensions. 1 Rweived March 26, 1924.
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The fondant mass exhibits varying degrees of plasticity, and phenomena of capillarity and surface tension are distinctly in evidence. All these phenomena will be treated here from a purely qualitative standpoint. I n the development of the invertase process, which is described later, visual inspection was sufficient for differentiation of plasticity effects of commercial importance. The effort required to obtain quantitative data would hardly have been justified from this particular standpoint. Certain manifestations of coalescence are exhibited which appear to be similar to the rearrangement of mixtures of sand and water to produce effects of maximum and minimum voids in piling. Owing to greater capillarity and surface tension effects, however, the relative displacement between sucrose crystals and mother sirup is not so great as between sand and water. Fondant may be pulled or stretched, and in many respects behaves similarly to putty. For instance, when pulled, the surface appears dry, but when compressed it assumes an oily or sirupy aspect. This phenomenon, which probably involves “seepage”-i. e., flow of liquid between the particles of solid due to shearing stress-is apparently due to alternate stretching and longitudinal compression of the sirup or oil films in fondant or putty, as the case may be. From the standpoint of commercial quality value the plasticity of fondant is one of the most important of its many interesting physical and chemical properties. The mother sirup film may be regarded as the “medium” and the minute sucrose crystals as the “suspension.” It may be stated qualitatively that the plasticity2 of fondant is primarily influenced by the viscosity of the sirup film, by the dimensions of the sucrose crystals (in relation to adhesion and external friction effects), by factors which determine the aggregation of sucrose crystals and production of “~tructure,”~ and by the proportionate amounts of solid and liquid phases. There is a possibility that the sirup film is plastic rather than viscous in certain cases-e. g., when colloids (egg albumin, corn sirup dextrins, etc.) are present. Fondant presents a distinct contrast to many plastic materials since, as a result of the solubility of the suspension (sucrose) in the medium (sirup film), there may, with change in temperature, be a ready transfer of substance from the solid to the liquid phase or vice versa, thus introducing an additional complication into the problem of variation in plasticity. Temperature variation also influences the plasticity of fondant, in common with that of other plastic materials, through direct effect on the viscosity of the liquid phase. The considerable change in mobility of fondant with change in temperature is an important factor in the candy maker’s art, since it permits the so-called “melting” of fondant and pouring into starch or rubber molds, whereby the fondant upon cooling may be made to retain practically any desired shape. The mobility of fondant may also, with change in temperature, be influenced by change in relative volumes of suspension and medium owing to difference in coefficients of expansion, the proportion of total volume due to voids being modified. Fondant appears dry when first made, but after standing 12 to 24 hours assumes a moister aspect. This is termed “ripening.” In the usual factory process the fondant, after being ripened, is remelted, colored and flavored, and cast in starch molds by means of mechanical depositors. The individual fondant pieces are usually allowed to remain in starch 12 to 24 hours and are then sufficiently firm for subsequent handling, this result being due to cooling and to ab2 The term “plasticity” is here employed in the sense of a complex property determined by two independent factors which must be evahated separately. These factors are “mobility,” the fluidity factor of plasticity, and “yield value,” the initial force required to overcome resistance before flow commences. 8 Bingham. “Fluidity and Plasticity,” p. 228
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sorption of moisture from the fondant by the starch. Ripening also occurs in these individual fondant pieces after they have been removed from the starch molds and coated with chocolate or other edible coating. The water absorbed b y the starch is withdrawn for the most part from the more superficial portions of the fondant pieces, thereby producing a crust, and the ripening which subsequently occurs is due to redistribution and equalization of water content in the fondant pieces by diffusion and capillary action. I n an experiment in which fondant was prepared by boiling (to 240° F.) a sirup containing 4 parts sucrose to 1 part of corn sirup by weight and then remelting the fondant a t 140” F. and removing from starch 24 hours after molding, there was a difference of as much as 3 per cent water between the exterior crust and interior of the individual fondant pieces, the maximum water content being 9.9 per cent. For the same reason a piece of fondant that has become rather dry on the surface as a result of exposure to air of relatively low humidity assumes a homogeneous moist appearance when worked or kneaded with the fingers. Changes in the density of piling or packing of the sucrose crystals and coincident, variations in the thickness and continuity of the sirup ana may also play a part in certain so-called ripening effects. Too great variation in the temperature to which the fondant is exposed during handling and manipulation in the factory is accompanied by danger of injuring its consistency, owing to solution of sucrose crystals in the liquid phase a t the higher temperatures and subsequent supersaturation and crystallization with production of crystals of excessive size at lower temperatures, thereby ‘causing granular consistency. Owing to greater water content, and consequently greater potential transfer of sucrose from solid to liquid phase and vice versa, this danger is greatest with fondants made from sirups boiled only to relatively low temperatures. The rate of drop in temperature may also influence the size of the crystals produced a t lower temperatures. The highest example of the candy maker’s art is an impalpably smooth fondant of rather fluid consistency. I n some instances it is desired that the fondant constituting the center of a confection be so mobile as to flow a t ordinary temperature, this type of goods being referred to as possessing a “flowing cream center.” In other types of confection it may be desired that the fondant center become completely liquefied. The gradual loss of moisture from the fondant in the finished confection during the period intervening between manufacture and consumption is an important factor for consideration. This is complicated in the case of certain types of confection by the addition to the fondant of fats and of colloidal materials, such as milk, gums, egg albumin, etc. Aside from the rancidity of fats and flocculation of colloids, however, the most important factor in the aging of the fondant type of confections is loss of moisture. Supersaturation of the sirup film increases with loss of moisture, crystallization of sucrose ensues, and the liquid phase diminishes in proportion to the solid phase, thereby causing gradual decrease in and final loss of mobility. The fondant center eventually becomes chalky white and hard, and the mobility factor becomes practically nil (within ordinary limits of time, pressure, and temperature). The production of larger crystals or crystal aggregates during this period contributes also to the hardness and granular consistency. These various factors suggest the utility of a sucrose inverting agent in the manufacture of fondant and fondant3 type confections, inasmuch as invert sugar tends to prevent. the formation of large sucrose crystals. Citric and tartaric acids and cream of tartar are used, but owing to their influence on flavor can only be employed in restricted proportions. With this limitation the inverting action that can be secured
N a y , 1924
INDUSTRIAL A N D ENGINEERING CHE,kfISTRY
by these reagents a t ordinary temperature within a reasonable time period is negligible and their inversion effect is practically restricted to that produced a t elevated temperature during boiling of the sirup from which the fondant is produced. Invert sugar sirup may be employed, but the amount that can be added is limited owing to its effect in producing too soft a consistency of the fondant pieces and thereby interfering with subsequent handling in the factory. An inverting agent which can be added to the fondant before the latker is molded in starch and coated with chocolate or other material, which does not unfavorably affect the color, flavor, or odor of the confection, and which causes sucrose inversion a t a sufficiently rapid rate a t ordinary temperature would, therefore, be an important asset in candy manufacture. The addition of yeast to fondant has been proposed by Booker,4 and this procedure has been employed commercially i n a rather restricted way-e. g., in manufacture of so-called “hand rolled” cream centers. The use of yeast is, however, subject to serious limitations owing to influence of yeast on color and flavor of the fondant unless used in small amount, t o the variability of commercial yeast, difficulty of control, etc. The foregoing considerations suggested to the writer the use of the enzyme invertase,s which has the further advantage of producing inversion a t leisure after the fondant has been coated with chocolate or other edible material. The fondant pieces can thus be made as firm as desired for subsequent mechanical handling in the factory, and the softening of the fondant can be effected after the goods are finished.
APPLICATION OF INVERTASE TO CONFECTIONERY MANUFACTURE Invertase action occurs, of course, in the sirup film constituting the liquid phase. The first effect is inversion of a portion of the sucrose in solution, thereby producing a mixed solution of sucrose and invert sugar with resultant increase in solubility. The sucrose crystals adjacent to the liquid film are then attacked, being either reduced in size or completely dissolved. Whereas the sucrose present in pure saturated solution is approximately 67 per cent, the maximum solubility of a mixture of sucrose and invert sugar in suitable proportion is approximately 81 per cent.B The usual effect attained is probably intermediate between these figures, Except in certain types of pure sucrose fondant of rather restricted use, corn sirup is also present, and exerts an influence on the solubility equilibrium. Search of the literature has revealed no adequate data regarding the solubility equilibrium of sucrose, invert sugar, and commercial corn sirup. The net result of the sucrose inversion is to increase the proportion of liquid phase a t the expense of solid phase, with consequent increase in mobility and improvement in consistency from a commercial standpoint. The influence of increased solubility in the liquid phase is so great as to more than counterbalance the loss of free moisture due to chemical combination of water and sucrose during inversion. Owing to increased solubility and higher solid content in the sirup film as a result of inversion, the viscosity of the film is increased; the tendency to cause reduction in mobility as a result of this factor is, however, more than counterbalanced by the transfer of substance from the solid to the liquid phase, As a result of the production of levulose and its hygroscopic Character, the subsequent loss of moisture from the finished goodti is greatly diminished and aging is considerably retarded. U. S. Patent 1,309,979. Paine and Hamilton, U. S. Patent 1,437,816. 6 Jackson and Gillis, Science, 63, 265 (1921). See also Herzfeld and Mollei, Z. V e y . RUbensuckerind., 83, 693 (1895); Girol, Bull. assoc. chim. sucr. disf., 86, 120 (1907). 4
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The, optimum hydrogen-ion concentration for maximum invertase activity corresponds to a pH value of 4.4 to 4.6. In order that the procedure employing invertase may be properly standardized and the inverting effect may always be proportional to the amount of invertase added, it is necessary that the liquid phase of the fondant be always adjusted to this p H value. This may usually be accomplished by adding 0.2 ounce of citric acid per 100 pounds of fondant. This proportion of citric acid is hardly perceptible to the taste. Because of the small per cent ionization of this acid and the nature of the relation between invertase activity and hydrogen-ion concentration, a moderate excess of citric acid is unobjectionable as far as influence on inversion is concerned. The citric acid also provides the necessary margin of safety for moderate variation in hydrogen-ion concentration due to the use of different grades of cane or beet sugar or corn sirup in preparing fondant. Invertase is added either a t the time the initial sirup is creamed or when the fondant is remelted for casting in starch. Since the volume of invertase solution employed is quite small and thorough incorporation in the fondant mass is essential, there is some advantage in adding the invertase while creaming-i. e., during a period of thorough agitation. I n practice the temperature of the fondant when remelted is usually not higher than 150 to 160” F. There is distinct evidence that the fondant exerts a certain degree of protective action against destruction of invertase a t elevated temperature. At high remelting’ temperatures (which are unusual in practice) a certain proportion of invertase is destroyed but, unless time and temperature of remelting are too great, this may be readily compensated by increasing the proportion of invertase originally added. Invertase may be used to advantage in varying proportions for all fondant type confections. Such confections of this type as are coated with chocolate may, for convenience, be divided into three groups. Group one comprises cheap bulk or pail goods, which are prepared with a maximum proportion of corn sirup. Such goods have a very thin coating of chocolate and must maintain a firm consistency in order to prevent crushing. The minimum proportion of invertase is to be used in this group, the purpose being merely to cause sucrose inversion to occur slowly a6 such a rate as to compensate as nearly as possible for the effect of evaporation of moisture on the consistency of the fondant. The retention of moisture is thereby increased by several per cent, and the shelf life is considerably prolonged. Experiments in which identical batches of chocolate-coated creams were prepared with and without addition of invertase showed an initial moisture content in the fondant of approximately 11 per cent. After a period of standing a t room temperature for four months, the moisture content of the pieces prepared without invertase was about 3 per cent, and that of the pieces prepared with invertase was as high as 6.8 per cent. The centers of the former were chalky white in appearance and quite hard, whereas the centers of the 1atter.appeared moist and retained their plastic character. A difference of only 1 per cent in water content has a great influence upon the consistency of fondant. It is interesting to note in this connection, however, that the total water content may even decrease to a consideraO
1 The “remelting” of fondant has in the foregoing been described in a simplified manner. I n practice it is subject to certain modifications. Frequently a sirup composed of sucrose and corn sirup in varying proportions and boiled usually t o a temperature of 230’ to 242O F. is added hot t o the fondant a t the time of remelting. This sirup is termed the “bob” and its addition has the effect of “stretching” or increasing the total amount of fondant and likewise of increasing its mobility and total water content (the latter only in case the “bob” is boiled t o lower temperature than the sirup from which fondant is produced). The addition of a “bob” represents an economy of time amd labor. Flavor and color and materials such as egg albumin are also added to the fondant at this stage.
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ble extent and yet, if sufficient inversion has occurred, the mobility and apparent moistness of the fondant may be practically as great as when the confection was originally prepared. I n other words, as far as effect on mobility is concerned, the transfer of substance from solid to liquid phase by inversion and consequent increase in proportion of the latter has been sufficient to oounterhhnce actualloss of water; os, in other words, the capacity of a given amount of water to maintain the liquid phase has been increased as a result of increased solubility. In group two a larger proportion of invertase is used, the purpose being to produce a rather soft or so-called “flowing” center-one which is sufficiently mobile to flow by gravity when the confection is broken. This group comprises medium and higher priced package goods, including advertised brands which may be shipped and sold over considerable territory. The consistency of fondant confections may be readily tested by cutting the confection in halves vertically. If the fondant is sufficiently soft, flow by gravity occurs and the fondant comes to rest at varying angles of repose, depending on consistency. Since the yield value here is less than the force of gravity, such very soft fondants are probably viscous rather than plastic. All gradations of consistency are possible varying from high percentage contact and external friction between sucrose crystals to purely viscous flow with free movement of sucrose crystals in the sirup phase. Fondant contains a considerable amount of minute air bubbles which have been incorporated as a result of agitation during creaming. One of the requirements for fondant of highest quality is that i t be snow-white in color. I n addition to the influence of the grade of sugar and the color of the microscopic sucrose crystals in the fondant, these minute air bubbles also play a part in determining the degree of whiteness.s When the fondant, as a result of inversion, becomes more mobile and flowing, the minute air bubbles tend to aggregate, and as a result of this and the increase in proportion of liquid phase the fondant becomes less white in appearance. This tendency may be counteracted by adding a small proportion of egg albumin (incorporated in corn sirup and sucrose solution) a t the time the fondant is remelted. The effect of the colloidal albumin is not only to introduce a certain proportion of air bubbles, but also to prevent or retard the aggregation of the minute air bubbles in the fondant. Furthermore, by producing a colloidal “ s t r ~ c t u r e ”egg ~ albumin exerts a “baffle” effect in preventing the excessively fluid consistency which may result from too great inversion. The proportion of albumin should not be so great as to produce a spongy consistency (marshmallow type). Group three includes types of confections in which it is desired to produce complete liquefaction-i. e., complete transfer from solid to liquid phase after manufacture of the goods is completed. These include confections with socalled “cordialized” fruit centers-for instance, those in which cherries, strawberries, raisins, and pieces of pineapple, peach, fig, etc., are dipped in melted fondant and the latter after cooling and setting is in turn coated with chocolate. The action of invertase on the fondant eventually cause8 complete liquefaction, the final result being a piece of fruit in sirup, the whole being encased in chocolate. The total water available evidently consists of that present in both fondant and fruit, the proportion of water in the latter depending upon the concentration of the sirup in which the fruit has been processed. Without inversion the total amount of water which it is practicable to have present in this manner is not s a c i e n t for complete solution of the sucrose crystals. In the case of pineapple, which is a very juicy fruit, it is possible 8
Bancroft, “Applied Colloid Chemistry,” p. 196.
e Bingham, “Fluidity and Plasticity,” p. 228.
Vol. 16, No. 5
by processing the fruit in a low density sirup, or by omitting processing altogether, and also by coating the fruit with a reduced proportion of fondant, eventually to secure complete liquefaction without inversion. The invertase procedure not only insures complete liquefaction under ordinary conditions, but also permits the use of a heavier fondant coating on the fruit. Furthermore, it makes possible the handling of the fruit in a drier condition prior to and during dipping in fondant, thereby increasing factory capacity at this stage. The rate of liquefaction is influenced by the rate of diffusion of moisture from the fruit, but can for all practical purposes be sufficiently controlled by the proportion of invertase employed. Invertase may be applied with advantage to bonbons as well as to chocolate-coated goods. Bonbons consist of molded fondant pieces coated with another type of fondant (frequently colored) instead of chocolate. A “short” dip ping fondant is used for coating-i. e., one which contains an increased proportion of sucrose. As a result of the increase in proportion of solid phase and elevation of the temperature range for plastic flow, such a fondant “sets” quickly when cooled. Conversely, the temperature range for plastic flow is extended downward with increase in proportion of corn sirup, and a definite minimum proportion of corn sirup is required for fondant which, within permissible limits of elevated temperature, is poured into starch molds by automatic depositing machines. It is not necessary, therefore, that bonbons, immediately after dipping, be placed in a cool room (artificially cooled when necessary and usually maintained a t 55 ’to 70” F.), as is the case with chocolate-coated confections. Chocolate coating, by virtue of its fat content and emulsified condition, retards evaporation of moisture from the fondant center much more effectively than a fondant coating. The latter is comparatively porous and as a result bonbons quickly dry out, first losing their luster and becoming spotted owing to local crystallization of sucrose; this crystallization is accelerated, owing to the high proportion of sucrose in the dipping fondant, and the white crystal spots give a faded appearance to the fondant coating in case it has been colored. Bonbons, with the exception of grades that are protected by a coating of sucrose crystals, are as a rule only salable for a few days after being made. Colloidal substances such as gelatin, gums, etc., are sometimes added to dipping fondant, the colloids serving to retard crystallieation of sucrose, The results obtained are, however, only moderately satisfactory. Invertase may be used to advantage both in the center and in the fondant coating of bonbons. The effect on the fondant center is the same as in chocolate-coated fondant goods and any desired consistency may be obtained; the effect of inversion in the fondant coating is to gradually produce invert sugar, which in turn retards sucrose Crystallization. The invert sugar also renders the fondant coating less porous and thereby retards evaporation of moisture. By using this process bonbons may be prepared of suEh character as to keep for months with no perceptible drying out, with very little loss in luster or gloss, and no spotting due to crystalliaation of sucrose. It is also of some advantage from this standpoint to warm the bonbons, within a certain period after dipping, to a temperature of 90’ to 120’ F. for a short period (10 minutes). This brief period of heating a t a moderate temperature does not cause any deformation of the molded fondant pieces due to plastic flow. This treatment in conjunction with the production of invert sugar by inversion tends to produce an exceedingly thin, shell-like coating. on the bonbon, thereby sealing it, so to speak. Sucrose inversion is accelerated during the brief period of warming. The luster and gloss are also intensified by increasing thehumidity of the atmosphere during the brief period of heating-
May, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Retention of luster is also greater when the finished goods are kept a t lower temperature ranges. This procedure greatly increases the shelf life of bonbons and other fondant-coated goods and makes it possible to use such pieces more freely in advertised package goods shipped throughout the country. Applications for patents10 to cover the use of invertase and also regulation of temperature and atmospheric humidity in relation to manufacture of fondant-coated confections have been made. Use of invertase in this manner also prevents the cracking that usually occurs after a period in confections composed of especially large fondant pieces. Another important result of increased solubility and density in the sirup phase resulting from sucrose inversion is the tendency, as a consequence of increased osmotic pressure, to retard and even prevent the growth of certain microorganisms, such as yeasts of the Torula type, which are capable of growing in highdensity sirups and which may even thrive in sucrose solutions saturated a t ordinary temperature. Such microorganisms frequently cause great financial loss to candy manufacturers owing to gas producing fermentations which proceed so far as to burst and shatter the candy. Such socalled “explosive” fermentations have been most prevalent in “hand-rolled” creams-i. e., fondant containing a very high proportion of sucrose or even consisting of sucrose alone without addition of corn sirup. I n such cases the solid content of the sirup film would approach the minimum of approximately 67 per cent. The increase in total solid content from a minimum of 67 per cent to a possible maximum of 81 per cent (this maximum may be increased by the solubility influence of other ingredients and by supersaturation) represents a margin which may be of vital importance in determining whether such growth of microorganisms may or may nst occur. The use of invertase has also made possible a rapid and continuous process for manufacture of fondant type confections which is more in keeping with modern manufacturing processes than the intermittent procedure hitherto prevailing. In this process, the temperature to which the initial sirups (including ‘%ob”) are boiled is increased, thereby decreasing the original water content of the fondant and rendering the molded fondant pieces more firm. This procedure eliminates the scrap which results from the mechanical handIing of fondant pieces when the attempt is made to produce a soft fondant by boiling the initial sirups to low temperature and high moisture content. As soon as the fondant is creamed it is at once remelted and cast in starch molds without waiting for it to ripen. The boiling temperature for the “bob,” or the sirup from which the fondant is produced, or for both, may be as high as 255” F., the exact temperature being dependent upon the proportions of fondant and “bob” and the type of goods being manufactured. As soon as creaming is concluded, and without waiting for the fondant to ripen, the fondant is remelted with addition of “bob,” one container being used for the entire operation of creaming and rcmelting, if desired. The melted batch is then immediately transferred to a depositor or other suitable mechanical device and mt in starch. The individual fondant pieces are only allowed to remain in the starch molds during the time required for cooling-e. g., ‘/I to 1 hour, instead of 12 to 24 hours as heretofore. I n other words, instead of relying upon the starch to reduce the moisture content of the fondant and thereby render it sufficiently firm for mechanical handling, a sufficient amount of moisture has been removed a t the beginning of the process by boiling the initial sirups to high temperatures. The net result is to yield molded fondant pieces that can withstand all txpes of mechanical handling and conveying 10
Patent applications filed on behalf of H. S. Paine and John Hamilton.
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without producing scrap, The action of invertase after the mechanical operation is completed produces the necessary transfer from solid toliquid phase and thus provides the requisite margin of safety against treatment which might otherwise ruin the consistency of the fondant by producing excessively large sucrose crystals and insufficient liquid phase. This process results in an increase in factory capacity at this stage, inasmuch as the fondant pieces remain in starch for a shorter period, and fewer starch molding “boards” are required for handling a given amount of material. Also, since the proportion of moisture removed by the starch is diminished, the reheating of starch in the drying rooms need be done less frequently. This process is advantageously used in modern factories operating by the gravity system of handling and conveying materials during course of manufacture, and tends to permit the process part of the factory operation to keep pace with the many ingenious types of machinery that have been introduced in recent years for the purpose of supplanting hand labor and increasing factory capacity. Applications for patents10 to cover the foregoing rapid and continuous process have been made. Invertase is, furthermore, advantageously used in types of candy such as fudge, marshmallows, and caramels which are intermediate in character between straight fondant type and other types of candy, but which have a consistency determined to a certain extent by the presence of sucrose. I n such types of candy invertase is employed primarily for the purpose of producing slow inversion and thereby retarding evaporation of water and aging. The consistency of these types of candy is greatly modified by the presence of added colloidal materials, such as milk, gelatin, starch, etc. I n the case of a confection of such typical colloidal gel structure as marshmallow, a variation of moisture content produces rather pronounced effects. I n employing invertase in the ways described above, it is obvious that precautions must be taken to control inversion so as to avoid a too fluid consistency of the fondant or the possible crystallization of dextrose due to over-inversion in a sirup film of high density. I n fact, control is probably the most important element in effecting this industrial application. This factor has been satisfactorily solved through the use of a carefully standardized invertase preparation of constant activity and by determining the most suitable proportions of invertase for each type of confection, the proportion being also varied according to whether it is desired, for instance, to secure a flowing center within 5 to 6 days after manufacture or after a period of 5 to 6 weeks. The proportion of invertase is also adjusted on the basis of the average time elapsing between date of manufacture and probable date of consumption, with proper allowance for margin of safety. As a result of the records made available by modern sales methods, control of inversion in this manner becomes quite feasible. A standard invertase preparation with little odor, flavor, or color has been placed on the market and is available in large quantities. Invertase is now in commercial use in confectionery manufacture with highly satisfactory results and is being used regularly by some of the largest manufacturers. The cost of invertase per pound of candy is usually only a fraction of a cent. This article has been written with the purpose of giving a chemical and physical explanation of various phenomena connected with confectionery manufacture and of demonstrating that by proper consideration of basic principles chemistry may be constructively applied to this industry in a fundamental way associated with processes of manufacture and resulting character of finished goods, and that it need not be confined to analytical control of raw materials and products.
