A Study Of Multi-Domains Food Systems - Research Paper Example

Strategies to minimize moisture migration between ice cream and the cone: A Study Of Multi-Domains Food Systems This paper examines the existing literature on moisture migration, tries to understand the causes and effects of the same in the case of multi-domain foods or food composed of components having different water content or water activity levels, seeks to understand how the phenomenon affects the production of such multi-domain foods, particularly frozen foods like ice-cream and also attempts to study the available research relating to prevention of moisture prevention in ice-cream cones. While the research points to the different physical and reactive properties of the water content and activity levels in the heterogeneous foods like ice cream, this study examines specifically two practices in the industry. One is the use of polysaccharides like trehalose in the ice-cream mix which helps prevent moisture migration and the attendant loss of crispness of the cone. The other is the introduction of impermeable barriers between the ice cream mix and the cone in order to prevent moisture diffusion as occurring between the two components or domains or even with the external atmosphere. The study finds that introduction of trehalose is superior to the introduction of the chocolate barrier in the cone as the coating. Introduction Moisture is of fundamental importance to foods like ice cream because it often causes deterioration in the quality of the food. The interactions of moisture with food are actually complex. Such interactions may relate to the characteristics of the elements that form the food or may be a result of intricate association with the environment. Among such interactions, moisture migration is a significant characteristic of multi-domain foods like ice-cream. The different domains mean different water activities in them so that moisture seeks to migrate from a domain of high water activity to another domain having lower water activity so as to achieve thermodynamic equilibrium (Sitkiewicz & Pałacha, 2006). Such migration of moisture can be minimized or controlled through several methods. However, among the different methods, two are seeking to be examined and their working principles analyzed. This particular study attempts to study a suitable method for controlling the moisture from the softer and wetter inner core ice-cream to the outside crispy cone. For this purpose, two alternative methods are examined. One of them is the reformulation of the cone by adding trehalose to it. The other is the use of an edible barrier, chocolate in this case, as the coating agent on the cone. In this research, the aim is to understand what water transfer is and how it operates in heterogeneous frozen foods like ice-cream packed into edible wafer cones. It is also important to understand the effects of such moisture migration on the ice-cream, why it needs to be controlled, what underlying theories are involved in the activity, what are the factors that affect it and what are the usual techniques adopted to control it. The main concern in doing the research is to know how to prevent the external cone in the ice-cream from becoming soft due to gain of moisture from the soft, moist ice-cream part by either of the two mechanisms stated before. The aim is also to know the particular mechanism of action as also the pros and cons of using either trehalose or chocolate in the cones as envisaged. In so doing, the research also attempts to examine previous research in the field and try, in particular, to understand their approach to control moisture migration in ice-cream cones. The final stage of research comprises the design of an experiment to test the method adopted for controlling the moisture migration in the ice-cream cone by using any one of the mentioned two methods. This design includes the evolving of suitable tests for responses as well as analyzing the results of the tests as to their reliability and accuracy. Finally, the aim of the entire research is to compare the actual research outcomes to expected outcomes and conclusions formed in the matter so that such effort can be of utility to other researchers or even of significance to commercial production of ice-cream, in general. Water activity and moisture migration Since moisture migration is caused by water activity, it is essential in first understanding the phenomenon of water activity. Such an understanding is critical to understanding the phenomenon of moisture migration that is the core idea around which this research effort is based. Water activity is a phenomenon related to the fundamental principles of physical chemistry and thermodynamics. Fontana of Decagon Devices avers that water activity determines both food stability and safety in relation to microbial growth, physical characteristics of the food and rates of deterioration reactions and also that water activity is a significant parameter that regulates the thermodynamic migration of moisture in multi-domain foods. Unless the water transport is controlled, the water migrates from a domain having higher water activity to the adjoining domain having lower water activity, the reason being a thermodynamic process that occurs continuously in attempting to achieve equilibrium state; the domain gaining water becomes soggy whereas the one losing water becomes dry and hard and can even crack (Fontana, 2008). Water activity is considered as the single most significant characteristic of food ((Taoukis, 1988). The term “water activity” describes the energy state of the water in the food and acts as the solvent or participates in some chemical or biochemical reactions (Labuza, 1977). Water activity affects food safety and stability as relating to microbial growth and also determines the physical characteristics of the food (Fontana, 1998). Foods that normally have high water activity are moist, juicy, chewy and soft texture (Bourne, 1987), whereas the normal low water activity foods have a texture of crispiness or crunchiness (Fontana, 1998). Also, significant lowering of water activity in foods having high water activity normally makes such food hard, tough, stale and dry, which is undesirable; then normally crispy foods became soggy after gaining water due to migration activity (Fontana, 1998). Brandt (1996) studied moisture migration in fruit and cereal mixtures and his conclusion based on this study clearly is that such moisture migration, which is caused by the water activity level differences in the two adjoining domains of cereal and fruit, results in water migrating from dry fruit having high water activity level to the cereal component which has lower water activity level; in the process, the fruit becomes harder and the cereal becomes soggy. Talens and others (2010) maintain that the rate of water transfer between individual components of multi-domain foods is one mechanism that helps determine the shelf life of the foods and that moisture migration causes undesirable physical or chemical changes in the food. Among the factors that predicate the deterioration in food quality, these researchers ever, the actual differences in water activity of the components which acts as the primary cause for the migration of water as also other factors like rate of diffusion and the equilibrium value are what determine the rate and quantity of moisture transport in such foods. Again, research also indicates that the regulation and control of moisture migration in heterogeneous foods is possible through using edible layers between the components of the food or by changing the water activity of those components (Coupland, 2003; Talens, et al, 2010). Labuza and Hyman (1998) to maintain that moisture migration is a dynamic process \which occurs in order to reach thermodynamic equilibrium in relation to the surrounding food components and the environment; the chief factors determining the rate and amount of such water diffusion or transport are, in their words, water equilibrium and the dynamics of transfer. However, these researchers point to mainly four mechanisms to control water transport in such multi-domain foods. These include adding an edible layer like chocolate between domains, changing the water activity of food ingredients, changing the effective diffusion rate of the water or altering the molecular mobility or viscosity of the matter in the entrapped powdery or amorphous phases (Labuza & Hyman, 1998). Controlling water activity and moisture migration in ice-cream cones Coupland, (2003) avers that moisture diffusion can be controlled by matching the water activities of the different components of the food by adding humectants which lower the water activity of the moist component (e.g., glycerol). He also says that effective humectants can lower water activity but at the same time ensure that the food retains its safety and taste. He continues in the article that such humectants need to be readily soluble in water, and also should not crystallize in it. He mentions another alternative to the use of humectants in the form of moisture-impermeable barriers like chocolate, which when used between the component interfaces effectively helps block the diffusion of water from one domain or component to the by using trehalose, w polysaccharide in reformulating the cone in the ice-cream cones. The aim of either introducing trehalose or placing barriers like chocolate between the ice-cream and the cone is basically in reducing the diffusion of water among components or into the atmosphere; however, the physical characteristics that are thereby controlled help in retaining the crispness of the cone and also the freshness and taste of the ice-cream. Labuza and Hyman (1998) note that physical properties like stickiness, texture or crystallization are determined by moisture diffusion and this, in turn, affects food shelf life or food stability. They note further that the domains in multi-domain foods exist in either crystalline or amorphous state of which the amorphous state is not in true equilibrium; loss of moisture can mean changes between these two states or phases. Commonly, salt or sugar is used to lower the water diffusion levels within multi-domain foods by controlled sugar crystallization, but these ‘stabilizers’ can alter the final taste of the product due to the sweetness or salty tastes that result (Hartel, 1993). Hartel also notes how some heterogeneous foods in which sugar is added to caramel or creams need the crystallization of sugar to be controlled although foods like ice-cream require the prevention of crystallization The more is the moisture content, the more is the rate of crystallization of sugar (Duckworth, 1981) and such rate of crystallization of sugar is predicted by the degree of temperature above the so-called glass-transition temperature subject to saturation of the water system by diffusing molecules (Roos & Karel, 1991). This glass transition temperature is a typical characteristic of powdery or amorphous substances and such amorphous components in multi-domain food systems can change phase between rubbery or glassy states along with certain marked changes to the thermodynamic an and mechanical properties of the materials, among others (Sperling, 1986). Plasticization or the adding of an ingredient like water, the actual molecular weights of the ingredients as well as the quantity or type of bonding interactions (Levine & Slade, 1988).helps facilitate such phase alterations and the existence in one state or the other is actually determined by the quantity and temperature of such ingredients (Labuza & Hyman, 1998), Amorphous substance is very hygroscopic and transform to the rubbery state in humid conditions which causes the food to become coarse and granular in texture (Roos & Karel, 1991). Trehalose use in ice cream cones Trehalose is a polysaccharide that finds use commonly as stabilizers in ice-cream formulations (Goff, 2003). The of such polysaccharides helps in increasing the viscosity, prevent whey-ing off, aid in better suspension in the mix of flavor enhancing particles, facilitate packaging by producing a stable foam having better cut-off and stiffness during freezing, prevent or reduce ice or lactose crystals from forming through the crystallization process from occurring during storage, enable a smooth texture in the final product, make it more uniform, help it lose less volume at storage, prevent it from melting and slow down moisture migration that can affect the stability and physical character of the ice –cream (Marshall & Arbuckle, 1996). Generally, ice-cream consists of emulsified fat, casein dispersed as micelles, some dissolved whey proteins, sugars, salts and polysaccharides (Goff, 2003). Goff also states that While the ice-cream mix is aerated and then frozen under shearing stress so that ice crystals and air bubbles get dispersed (p. 1). Also, the emulsified fat coalesces somewhat and the mix is freeze-concentrated (Goff, 1997). The resulting ice-cream is greatly viscous and is also relatively more stable and has improved texture, while the trehalose or other polysaccharide does not add to the sweetness to any significant amount so as to affect taste. Again, in as much as crystallization of ice adversely affects texture significantly in ice-creams (Hartel, 1998), polysaccharides (like trehalose) when added to ice-cream formulations greatly help reduce the rate of recrystallization of ice (Hartel, 1998; Marshal & Arbuckle, 1996).While the stabilizers used in ice-cream (like trehalose, gelatin or carrageenan) are well known to affect ice crystallization, their mechanism is not fully understood (Hartel, 1999). Trehalose-like polysaccharides also do not affect the freezing properties of an ice cream mix like freezing point depression, enthalpy of melting or even heterogeneous nucleation and do not affect the initially occurring ice crystallization during ice-cream manufacture (Flores & Goff, 1999a, 1999b). Neither is there any appreciably observed correlation between the viscous ice-cream state and the rate of re-crystallization nor is the use of stabilizers related to the change in glass transition rate (Goff, 2003). However, research does indicate that stabilizers like trehalose do affect the rate of diffusion of moisture during crystal formation due to temperature variations or such migratory rate of the moisture away from the surface of the crystal during its formation (Bolliger, et al, 2000; Flores & Goff, 1999a, 1999b; Goff, Ferdinand & Schorsch, 1999; Regand & Goff, 2002a, 2002b).The functions of trehalose that permit its use in ice-cream cone reformulation include its mild sweetness and flavor-enhancement ability as compared to sucrose, its solubility in water, it being more soluble than sucrose at higher temperatures, its chemical stability during storage or processing, its unique chemical structure that enables it to remain stable even under low pH conditions at high temperatures, and its non-participation in Maillard reactions with amino acids or proteins . Added to this is its effectiveness in reducing water activity, high glass transition temperature as compared to other disaccharides, its capacity to depress freezing point of products (e.g., ice-cream) and its low hygroscopic nature which permits it to remain free-flowing even at high relative humidity and ability to reduce caking when used with sugar (Hama, 1999). Use of chocolate barrier in ice cream Coatings made of chocolate are excellent barriers to water vapor and this has been well demonstrated by Biquet and Labuza (1988).The effectiveness is due to the dispersion of fat or cocoa butter throughout the matrix (Labuzza & Hyman, 1998). However, such a chocolate edible barrier has limited uses due to the need that the barrier must be edible. However, the most common application is of such edible barriers that are impermeable to moisture and hence enhance the crispness or stability of the products is in confectioneries, frozen bakery goods or frozen desserts and ice creams. Chocolate can help reduce moisture diffusion when it is used to coat the interface adjacent to the ice cream mix and the cone retains its crispness during storage and till consumption. The solution to this problem is usually sought in applying a moisture barrier to the ingredient that has to be protected against moisture. Hydrophobic substances such as oils and fats, optionally in the form of chocolate, acetylated monoglycerides, shellac, natural waxes, and zeins, are widely used as the barrier material. The barrier characteristics of such materials are, however, not always adequate or sufficiently stable and sometimes there are also problems with regard to taste. Cocoa butter or a fat substitute for cocoa butter and also sugar and cocoa pieces The fat composition must ensure that the pieces, or the coated pieces, do not soften but remain crispy in a non-frozen aqueous environment such as a dairy product. However, it has also been noted that such moisture barriers cannot adequately withstand an aqueous environment such as that of dairy products including ice cream. Also, the barrier characteristics are also not uniform. It is also somewhat difficult to apply such materials in coating irregularly shaped, moisture-sensitive food ingredients e.g. nuts or cake so that the barrier is uniformly distributed. Generally, thicker coatings may need a fat content that may be too much on the higher side in ice-creams, since the taste gets affected. But the moisture resistant behavior of fat-based coating like chocolates can be improved by the addition of certain particles, so as to help the cone retain its crispness for a longer time. The coating material can be applied by means of any coating process commonly used in food technology, such as sugar coating, i.e. rolling in a fluidized bed, immersion, spraying or stirring, at a temperature so that the fat is in the molten state and also solidifies rapidly after application. Again, immersion of particles in a coating fluid is another technique widely used in the frozen and dry food industry and no special equipment is necessary. The layer thickness depends on the viscosity of the coating material and also on the rate of solidification of the molten chocolate upon application. However, spraying, another method for coating with chocolate in the fluid state can also be applied. But, since cocoa powder is hygroscopic, filling with such a method is not permanent protection and may not fully recommend. Conclusion While there are several methods of regulating moisture migration in heterogeneous foods, the specific nature of ice- cream mixes, the need to retain or enhance newer flavors, need to cater to altering tastes, prevent color or flavor losses and also the essential need to retain the textures of the food may mean adoption of either the trehalose method as stabilizer in the ice cream mix itself or by applying a chocolate coating to the cone of the ice-cream. While both methods have their benefits and limitations, the use of trehalose due to the qualitative change experienced by such use and also due to the high value of the product produced by use of trehalose may mean that the former method is preferable. The other method, of cocoa fat or chocolate as the impermeable barrier on the cone itself has its disadvantages with regards to the variety of ingredients that are nowadays included in ice creams. 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