Characterization Techniques For High-Quality Ice Cream Production

This is a report on the measurement techniques used in characterisation of a formulated product. I have chosen ice cream to write on . What i would need you to do is read through what I have done, and make some changes and additions .I do not need the whole body changed. I've attached two files, one contains the first draft I tried to do myself, and the second contains a list of questions, all these questions must be correctly answered to build the body of the essay. In order words, before you send me your final draft, make sure you can see the answers to all questions in your body of work.

You must also provide 4 sets of data from literature.So if you read through questions A-F,you'd see you have to talk about one major characterisation technique and three others, which makes four in total. Therefore provide each data analysis(where the technique was used to get certain results) for each technique.

Lastly, the deadline is monday, so I'd really appreciate it if I could get an update/a draft, no matter how little. Just so I'm sure you are working towards the right thing.

The Manufacturing of Ice Cream

The manufacturing of ice cream involves various processes. These processes, such as freezing, are vital in determining desirable aspects of the ice cream like its overall texture. These aspects inform what ice cream brand a customer purchases. Therefore, manufacturers are normally keen on having the best processes to produce the highest quality ice cream that satisfy the market demands.

Ice cream is a popular aerated dessert which is frozen. However, this dessert contains high quantities of fat which can result in adverse health effects on a person. The ice cream manufacturers therefore try hard to come with designs that have low fat contents without altering the taste and sweetness of the ice cream. Hence, various methods or techniques are used in the process of characterizing the ice cream to enhance the final performance such as the fat content, aroma, and smoothness. This paper discusses some of the characterization techniques which are applied in ensuring that the overall quality of ice cream is as desired (Aboulfazali et al, 2015).  

The physical characteristics of ice cream makes it a formulated product. Ice cream is composed of various ingredients which are selected, processed and combined in a specific way to produce the end product. The ingredients are combined in different proportions to achieve the different specifications for the different ice cream varieties. The proportions are also carefully calculated to maintain the other aspects of the ice cream.

Ice cream is made up of water, milk, cream, sugar and other flavoring additives combined in different proportions. These additives in addition to giving the ice cream flavor, help maintain the physical nature and the stability of the frozen structure when combined in a pre-defined ratio (Aboulfazali et al, 2016). This is crucial in making sure the ice cream is neither too liquid nor too solid, thereby attaining the perfect rigidity for the ice cream which is normally when the ice cream temperature is between 5 degrees Celsius and 10 degrees Celsius.

Ice cream is a formulated product since it is produced by mixing different proportions of the various ingredients following a given procedure that satisfies the grade and quality of ice cream that is desired.

The concentration of different components in the ice cream for the standard brands include the following:

• Milk Fat – 10% to 16%
• Milk Solids Not Fat (MSNF) - 9% to 12%
• Sweeteners, Emulsifiers and Stabilizers– 13% to 17%
• Overrun – 100% to 120% (Aime et al, 2009)

The nature of ice cream makes it a foam and emulsion simultaneously. It consists of a dispersion of microscopic particles that are less than 0.5mm in size superimposed on one another. The air in the ice cream does not combine with the other ingredients of the ice cream. This air forms the small bubbles called the foam.

Characterization Techniques for Ice Cream

The ice cream has emulsifiers as well. These are the particles sticking to the interfaces of ice cream preventing its structure from collapsing. The emulsifiers therefore are the ones that maintain the stability of the ice cream’s structure.

Ice cream also contains dissolved substances that alter its freezing temperature. This results in the ice cream’s freezing point being different from that of water. The presence of these solute components is the reason for this increased range of temperatures from the onset to the actual occurrence of the freezing process (Arbukule, 2009).

 The Components of Ice Cream

The components of ice cream are primarily frozen emulsions of five basic ingredients. These are:

Ice Crystals- these are the frozen water component of the ice cream. They are formed by putting the ice in the ice cream container when the base part of the water content starts to freeze thereby giving the ice cream its solidity and body. The texture of the ice cream is determined by the size of the crystals, that is, how fine or grainy is the final ice cream. For this reason, one should aim more at regulating the size of the ice grains so that it is maintained as small as possible (Boff et al, 2013). This is however subject to the specifications and desired ice cream type. Regulating the ice crystals to the desired size produces ice cream with the specified texture.

Air- this is the invisible part of the ice cream. The air plays a big role in the overall nature of the final ice cream product. The amount of air whipped into the ice cream is represented as the overrun value of the ice cream.

Ice cream generally has a porous - like structure. The tiny air pores found in the mixture of the ice components determines the taste, texture and volume of the resultant ice cream. It also maintains the general consistency of the ice cream. Ice cream varieties with very low overrun tend to be less tasty as compared to those with higher overrun. However, having overrun that’s too high decreases the quality of the ice cream. High overrun increases the volume, meaning the actual amount of ice cream per kilogram of ice cream would be small. Since air is just found freely and increases the volume of ice, its content in the ice should be reduced, thereby increasing the quality of the ice cream. Without doing this, the volume of ice cream can increase to appear as if it’s big yet it is just filled with air bubbles (Cao-Hoang, 2010).

The Components of Ice Cream

Fat- the fat component of the ice cream is basically provided by the butterfat in the milk. Its main purpose in the ice cream is to add richness. It also stabilizes the base of the whole ice cream mixture.

The density of the ice cream is determined by the amount fat in it. Higher amounts of fat improves the density while lower amounts decrease it. This is dependent on the overrun values since the volume of air in the ice cream influences its volume.

The milk fat in the ice cream also provides the smooth texture of the ice and improves the flavor of the ice cream.

Sweeteners, Stabilizers and Emulsifiers- various ingredients for example sugars, syrups or honey are added to provide the sweetness in the ice cream. Ingredients such as these are collectively referred to as sweeteners. The sweeteners affect both the body of the ice cream and its texture. They also acts as the impurities that alter the freezing point. This ensures that the ice cream does not freeze resulting in a very hard solid. The stabilizers balances the mixture both chemically and structurally while the emulsifiers such as proteins help in coalescing the droplets of fat in the ice cream.

Reducing the sweeteners component of the ice cream therefore can result in a reduced quality of the ice in terms of the body and the stability of the ice-cream (Carr et al, 2012).

MSNF (Milk Solids Non - Fat) - these include non-fat milk components like proteins and mineral salts and other flavors. These solids contribute largely to the body and texture of the ice cream. They also add flavor and sweetness to the overall mix. These solids should be regulated so that they are not too much nor too little to achieve the required balance for the given ice cream variety. This contributes to the overall quality and grade of the ice cream.

 The Babcock is a scientific technique used in the determination of the percentage content of fat in milk. The technique mainly relies on the principle of dissolution by the addition of an acid or a mixture of acids, in this case a mixture of glacial acetic acid and sulfuric acid.

The Babcock method is simple to execute and accurate when properly conducted. The steps below represent the procedures followed in the Babcock method.

• Mixing of the sample – this involves warming a sample of the ice cream at a temperature of 40 degree Celsius. The sample is then mixed with sodium hydroxide. This is done by adding some granules of powdered sodium hydroxide to the warmed sample. Adding sodium hydroxide results in emulsification of the ice cream sample.
• Weighing – using a pipette, 9 grams of the sample (now mixed with sodium hydroxide) is obtained through weighing.
• Babcock process – this first involves taking an equal amount of glacial acetic acid and sulfuric acid and mixing the two.The acid mixture is then allowed to cool. 15 mm of this acid mixture is then added to the ice cream – sodium hydroxide mixture in a bottle with a graduated neck. The acid mixture dissolves all the solid matters of the ice cream except the fat. The mixture is then shaken and the bottle containing the mixture placed in a steam bath. Heat is then applied until the mixture turns dark in color.  Thereafter remove the bottle and allow it to cool for 10 minutes. Transfer the contents of the bottle to a centrifuge tube and then place it in a centrifuge. After removing the mixture from the centrifuge, transfer the mixture back to the bottle. Whirl the mixture and then add hot water after every 3 minutes as you whirl, for a total of 15 minutes. The hot water will help in raising the melted fat to the graduated neck for recording. This will then be followed by removal of the bottle and placing it in water at a temperature of 55 degree Celsius. The percentage content of fat will then be read by rubbing the neck of the bottle using powdered calcium carbonate.  (Analytical, 2008).

An application of the Babcock Technique was by E. W. Bird, D. F. Breazeale and G. C. Sands in Iowa State College in determining Nature of Fatty Materials in Buttermilk. The technique produced the results in the table below.

The Babcock Method for Ice Cream Production

The Babcock technique was applied to 20 samples, every two samples drawn from 10 different Buttermilk products. The analysis aimed at comparing the fat quantity in the different products as well as determining the average quantity of fat among the different products.

Advantages of direct technique

• The Babcock direct technique of characterization is rapid. The technique produces results instantaneously and therefore saves time for any ice cream manufacturer that is measuring the content of fat in the ice cream. The rapidness of the technique serves to reduce the time taken during production and in turn production cost for the manufacture of ice cream, making it economically viable option.
• The direct technique of characterization produces a simple process or recipe for the case of the ice cream. This simplicity enables one to easily prepare an ice cream at home by following the procedures. Thus, direct technique simplifies the process of making ice cream (Chain et al, 2016).
• The Babcock technique of characterization is highly accurate method. In comparison to other characterization techniques, the Babcock method produces results that are more reliable and credible. This makes this technique the most efficient for characterization of the formulation of ice cream.
• The Babcock direct technique is cheaper method of determining the percentage content of fat in the ice cream. The affordability aspect of this technique makes it a preferable fat determination method since it reduces the cost of production which would otherwise be high if other methods were used.
• The direct technique produces a clear and simplified composition of the ice cream’s structure, its ingredients, and the proportional mix of these ingredients that produces an overall ice cream that is stable and consistent (Gomes, 2013).
• The Babcock direct technique is simple to understand and execute. The procedures involved in the Babcock method are relatively straight forward making the process less susceptible to external factors. The simplicity of this method serves to increase its efficiency.

Disadvantages of direct technique

• The Babcock direct technique only gives information on the percentage content of fat in the ice cream. Information on other aspects of the milk fat such as the quantity of phospholipids in the ice cream cannot be obtained using this process. This makes the method only limited and hence cannot be relied upon to generate more information on the milk fat.
• Understanding the nature of some components such as the emulsifiers and stabilizers may be challenging. The complexity in structure, properties and behavior of these components in different composition require a deeper examining and understanding of the components.
• The Babcock direct technique is limited to determining the percentage of the content of fat in the ice cream. This leaves out the other components of the ice cream such as air and water in form of ice crystal. This makes using the technique costly since other methods need to be applied in order to produce a more conclusive characterization of the formulation of ice cream.
• Computation and addition of emulsifiers and stabilizers requires skills. This is crucial in achieving the desired specifications for the ice cream. Any miscalculation in terms of the percentage and proportion of the major components, flavors and additives can result in distortion of the quality of the resulting ice cream (Gomet et al, 2010).
• Issues of temperatures balance and the stabilization components require a lot of concentration and skills. Resources and equipment required for the temperature balance, for instance, the refrigerators or the chillers are expensive. Achieving the required conditions for producing the best quality ice cream can demand a great commitment of resources.
• The Babcock direct technique involves the use of a mixture of acids (glacial acetic acid and sulfuric acid). This results to high concentrations of acid in the process. These concentrations have adverse effects to any chocolates or sugars used in the ice cream. Hence making it an unsuitable method for products with chocolates and sugars. This implies that for many of the ice cream varieties that have sugar and chocolate components in them, the Babcock method can either be applied to the milk before it is mixed with the other components that make up the ice cream, or abandoned in favor of another technique with less effects on the chocolates and sugars.

There are other techniques that can be applied in the characterization of the formulation of ice cream. These techniques include the following:

• Observation Method By  Direct  Optical Microscopy
• Physiochemical Technique (Harigan & Mccance, 2014)
• Automatic Ice-Cream Characterization by Impedance Measurements for Optimal Machine Setting.

Observation Method by Direct Optical Microscopy

In this method of characterization, an optical microscopy with episcopic coaxial lightning is applied to categorize ice cream in situations of mono directional quiescent freezing, the structure of a frozen mixture of ice cream without an overrun.   The Observation method by direct optical microscopy techniques depends on knight flux which is bounced back by the surface of the sample.  Besides, these light fluxes which have been reflected back determine the resulted contrast and concurrently the light fraction from the absorbed flux incident from the reflected light at various orientations (Hamayouni, 2008).

  Once a separation is done, the ice cream cups get stored at a temperature of -25 degree Celsius. The frozen samples of the ice cubicles are immersed in liquid nitrogen in order to fully halt the process of crystallization and commence solidification of the fats to completion. Later, the samples get placed in a cold room and maintained around the same temperature and the cut surface get polished using a microtone in order to have a smooth surface with a thickness of roughness lower than 1 um. After ensuring the quality of the surface, using stereomicroscope, the sample is observed together with an optical fiber and a digital video camera for episcopic coaxial lightning (Hamayouni, 2010).

Observation Method by Direct Optical Microscopy is also applicable for cases where overrun is present. The basis for allowing aeration in the technique is to measure parameters such as freezing rate of the ice crystals found in the ice cream, distribution of the sizes of these ice crystals as well as the distribution of the sizes of the air crystals in the ice cream. Overrun is an important aspect since it influences the growth rate of the ice crystals. Increase in the overrun limits the growth of the crystals thereby serving as a good control component. The freezing rate is vital in determining the size of the ice crystals, the size in turn determines the texture of the final ice cream product. Below is an illustration of the SSHE (Scrap Surface Heat Exchanger) freezer design for the Observation Method by Direct Optical Microscopy technique with overrun.

Techniques for Characterizing Ice Cream Formulation

Observation Method by Direct Optical Microscopy done by (O. Hernandez et al, 2015) in a discriminating microscopy technique for the measurement of ice crystals and air bubbles size distribution. The measurement focused on sorbets and produced the data represented in the graphs below

Sorbets are frozen formulated liquid mixes similar to ice creams (O. Hernandez et al, 2015). The experiment observed the nature of both air bubbles and ice crystals as well as the interaction between the two aspects using the Direct Optical Microscopy method.

Physicochemical characterization of the ice cream

Physicochemical characterization in this case is a combination of five main techniques; Crystallography, Thermomicroscopy, Calorimetric Techniques, Spectroscopic Techniques and the Gerber’s Method. However this paper will only focus on the Calorimetric Techniques of characterization of ice cream.

The Calorimetric Techniques apply the use of an Optical Differential Scanning Calorimeter Cryomicroscope. This device combines the Calorimetric and Optical instruments into one device. The Differential Scanning Calorimeter (DSC) measures the calorimetric parameters while the Cryomicroscope provides the optical and visual analysis of the ice cream. The figure below shows the Optical Differential Scanning Calorimeter Cryomicroscope.

A sample of ice cream is placed in the specimen chamber of the DSC stage. Another sample is placed in the control chamber. The temperature of the sample in the specimen chamber is varied and changes in the energy flow and the nature of structures of the ice cream is recorded. Observations are also made in comparison with the properties of the second sample in the control chamber.

Observing thermal properties using this Calorimetric technique is important in determining the behavior of the sample variety of ice cream tested in different environments. This information would then inform the best temperatures for the manufacturing, storage and transit phrases to ensure the quality of the ice cream is not affected (Yuan & Diller, 2005).

The observations made by (Yuan & Diller, 2005) produced data represented in the plot below. The procedure involved the cooling of the sample of ice cream from a temperature of -3 degrees Celsius to -30 degrees Celsius. The volume of the ice crystals in the sample was then observed to produce the plot below. The results indicated an increase in the size of the ice crystals up until a certain point where the growth rate decreases and almost stagnates.

Automatic Ice-Cream Characterization by Impedance Measurements for Optimal Machine Setting

This technique applies the EIS (Electrical Impedance Spectroscopy) for the characterization of the ice cream varieties. An overview of the technique being, a sample of an ice cream variety is placed in direct contact with the electrodes. The sample acts as the electrolyte stimulated with a predefined amount of sinusoidal test voltage. In this instance, machines that are meant for storing ice cream varieties and maintaining them at specific temperatures are programmed in relation to the various varieties of ice creams.

Conclusion

In the technique, the samples of the different varieties are incubated inside a thermal chamber which provides the desired temperature with the uncertainty equal to a value of 0.1 degree Celsius. Measures are then taken at two temperatures which are 35 degree Celsius which is the microbial sensor system temperature and 4 degree Celsius which is the standard ice cream mixture temperatures. An LCR meter Agilent E4980A is then applied in determining the electrical characteristics of the samples. This activity is regulated by the help of a USB connection to a pc which tentatively processes the data acquired (Murakami & Okos, 2009).

  A sample of 10ml of the ice cream variety which is being tested is then placed inside a cup-shaped container that has electrodes made of stainless steel. Two sensors configurations are then used. The first having two electrodes and the second containing four electrodes which are shorted together. The difference is due to the electric field that is to be generated during the process. The geometries of both the sensor are simulated by the use of a software Comsol Multiphysics v4.  The second sensor usually generates the strongest electric field.

Automatic Ice-Cream Characterization by Impedance Measurements for Optimal Machine Setting technique measures three main aspects of the ice cream varieties tested. These aspects are milk fat content, salt concentration and the ph. Value of the ice cream. The resistance value as read form the LCR meter Agilent E4980A gives information on the rate of conductivity of the ice cream.

Fat is generally a poor conductor of electric current, this implies that high amounts of milk fat in the ice cream would make it less conductive. This is read from the LCR meter Agilent E4980A as high resistance when milk fat amounts are high and low resistance when milk fat amounts are low.

In contrast to milk fat, salt is a good conductor of electric current. High levels of salt concentrations in ice cream would make the ice cream more conductive. The LCR meter Agilent E4980A would record low readings for the resistance when the salt concentration is high, and high resistance when the salt concentration is low.

The ph. Values however, cannot be conclusively determined using this technique. The electrical parameters measured by the LCR meter Agilent E4980A do not exhibit a high enough correlation with the ph. Values to conclude the existence of a relationship. This therefore means that the parameters would only explain a fraction of the ph. Value of the ice cream variety sample, hence making the findings unreliable.

(Marco G et al, 2012) found the value of the resistance as observed from the Automatic Ice-Cream Characterization by Impedance Measurements for Optimal Machine Setting to be as indicated in the table below

The data was collected from a sample of 21 ice cream mixes. The mixes were then divided into three different varieties; 10 creamy mixes, 5 frozen yoghurt mixes and 6 fruit based mixes. The creamy mixes had the average lowest resistance value from both sensors A and B. this implies that the creamy mix had the highest salt concentration of the three varieties, making it more conductive.

Examples of microstructures which are determined by the above techniques are given below. According to Physicochemical characterization, we have the following parameters (Peterson & Shigeteni, 2008)

• values
• Proximate composition
• Instrumental calorimetry
• Total soluble solids
• Overrun values
• Date fiber
• Meltdown
• Irritable acidity
• Ash content
• Protein content
• Milk Fat content
• Moisture content

According to Observation method by direct optical microscopy, below are some of the microstructures and physical properties determined

• Irritable acidity
• Total solid,
• Protein content
• Milk Fat content (Peterson & Shigeteni, 2008)
• Freezing Rate
• Size of ice crystal distribution
• Air bubble size distribution

According Automatic Ice-Cream Characterization by Impedance Measurements for Optimal Machine Setting the parameters measured are:

• values
• Viscosity
• Total solid
• Protein content
• Milk Fat content
• Salt concentration

Viscosity, this property is one of the significant parameters since it can result in a desirable body a texture of the ice creams. Thus, this determination of the viscosity is important since it aids in determining the effect of DF on the mixture of ice creams. The addition of DF increases the viscosity behavior.

 Date fiber- the addition of date fiber greatly impacts the performance and quality of ice cream. For instance, with an increase of date fiber, the overall coloring properties of the ice cream. Besides, it enhanced timing in dripping, melting times, viscosity and the overrun values.  Besides, it promotes the physiological aspects and the nutritional aspects by promoting the thermal properties of the overall ice cream product.  In addition, these physical and microstructural properties enhance the market value of the overall product by increasing its appearance, texture, aroma, overall acceptability and flavor (Peterson & Shigeteni, 2008).

The air bubble size and overrun values determine the texture, taste and volume of the ice cream. Whipping air into it causes an increase in its volume. This may seem as an increase in size, but it reduces the quality. The amount of air added during the production controls the process of ice crystal formation and by extension the texture of the ice cream. The overrun also has a huge influence in the taste of the ice cream, low overrun values make the taste too sweet while high overrun makes it loss it’s sweetness. Therefore, a good balance of overrun would produce the desired sweetness. (O. Hernandez et al, 2015)

The milk fat content of the ice cream varieties affects two aspects of the ice cream. These aspects are the density and richness of the ice cream. High fat content increases its weight and consequently its density.

The ph. Values and salt concentrations affect the taste of the ice cream. Low ph. gives the ice cream a sour taste while high salt concentrations make the ice cream bitter. (Marco G et al, 2012)

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