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Introduction

While making ice cream in the industry is challenging it won’t be the same as homemade. It varies from factory to factory how ice-creams are made depending on the equipment and volume of production

The ice cream will not be of high quality when the ingredients are simply mixed together and frozen. Due to the crystalline structure of the matrix on top of the ice crystals, air bubbles, and fat droplets, this process does not produce the microstructure of the ice crystals. In order to make 1000 liters of ice cream instead of just one bowl, you’d need different equipment and process steps. Making ice cream on a larger scale raises new concerns that you might not have ventured into as a homemaker! We’ll take a closer look at ice cream production.

Mixing liquid and dry ingredients

The preparation of the mix is the first step in making ice cream. Utilizing the shortest time possible to mix and dissolve the ingredients minimizes energy consumption. 

When the ingredients are mixed in an inadequate amount of quantity, whether on a small scale or a large scale, the texture and taste of the food will suffer. In large scale factories, the ingredients are measured and dosed automatically; on a small scale, the ingredients are metered and dosed manually. The mixing tank is used on a large scale, the ingredients with the stirrer are heated to the correct temperature without being overheated, this helps to mix the ingredients evenly and prevent damage to heat sensitive ingredients, 

As soon as the liquid ingredients are added, the heating and agitation begin; before adding the fats, the solids are melted. The dry ingredients are added next. 

Stabilizers are the hardest ingredients to dissolve. Before being added to the mix tank, they are dry mixed with at least an equal weight of sugar to aid dissolution to prevent the formation of lumps, the stabilizer mixture is slowly added to the tank to ensure even dispersion and avoid the formation of unevenly dispersed stabilizer. 

To prevent lumps, milk and whey powder are also slowly added. If any lumps form in the mix tank, the outlet contains a filter to remove them when whey proteins are added to the mix, they should not be heated to higher than 85 c. Since milk products denature at high temperatures, that is why they should not be heated above that.

 If the flavor and color have heat sensitivity, then they are added after pasteurization. Mixtures should be homogenous or heated to above 65 degrees Celsius when all the ingredients are added 

Homogenization and Pasteurization

Pasteurization removes all microorganisms from the mix, making it safe for consumption. A homogenizer breaks down the fat particles into droplets. Mixing up to pasteurization temperature requires a large amount of heat. Heating takes place in two stages to maximize heat efficiency. In the first stage, the mix is taken from the mix tank and passes through a plates heat exchanger

First, the incoming mix is mixed into the first flow system, and then the already homogenized and pasteurized mix goes into the second flow system. Thus, the incoming mix is heated, and the homogenized and pasteurized mixture undergoes the first cooling stage, which is necessary before the next stage of the manufacturing process.

Hot water is used to heat the mix in the second step of heating. It is important that the mixture is sufficiently hot to achieve pasteurization temperature after homogenization at the end of this process. To avoid milk proteins and off-flavours, the temperature is capped at 82 degrees Celsius.

During homogenization, the hot mixture is forced through a small valve at high pressure. In effect, these large fat particles have been converted to small droplets. In order to prevent clustering of small fat droplets, sometimes the second homogenization step is performed at low pressure

Proteins in milk absorb the bare surfaces of fat droplets. The proteins are mostly absorbed on the fat side since the protein molecules on the outside of a droplet can interact with each other and make it harder for them to come into close contact, a process called stabilization.

For pasteurization to take place, the mixture must be held at pasteurizing temperature for an adequate period of time in the holding tube. Both the length and diameter of the outlet pipe must be chosen to ensure this occurs.

A three-step cooling process follows pasteurization  

  • Heat is transferred from the mixing tank to the incoming mix 
  • After that, it is cooled with water 
  • It is then cooled to 4 degrees Celsius with chilled glycol

Ageing

Mixtures are pumped into ageing tanks once they have been cooled. Mixtures are stored in these tanks to minimize exposure to other sources of contamination from the atmosphere 

The mix will be kept between 0 to 4 degrees Celsius and gently stirred at this point. 

The minimum amount of agitation is needed to avoid warming up the mix so that heat-sensitive ingredients are not heat-sensitive. Colours and fruits extract can then be added at this point   

Ageing involves two important stages:

  • In the first place, it absorbs the surface of the flat droplets, replacing some of the milk protein 
  • A second stage occurs when the fat within the droplets crystallizes. 

It takes time for crystallization to occur because nucleation must take place at every individual droplet. In order for crystallisation to occur, and for some protein replacement to take place, ageing is a six-hour process, while two hours is sufficient for major products 

To produce ice cream at the next stage, both of these processes are needed. Without them, it is difficult to incorporate and stabilize the air bubbles when the mix is frozen in the ice cream mixture, And the next step is the mix will test under a laboratory process to check the viscosity and to check the total amount of fats and solids and to ensure that stabilizers dissolve components in water, ensure the mix is microbiologically safe and pasteurized properly.

We have formed only one part of the microstructure of the ice cream so far. Others are created in the next stage of the process, freezing 

Freezing and hardening

In the manufacturing process, freezing is the key step. To produce ice crystals, the mixed mix has to be aerated, frozen, and beaten together in the factory freezer. Aerating, freezing, and beating have been the basic icecream making process for hundreds of years.

In modern ice cream freezers, viscous liquids can be removed or added to temperature. A dasher plays an important role in the freezer. The dasher has two functions: to mix at high shear and to scrape off ice crystals. 

There are two types of dashers: open and closed, which are used for different types of products.

Open dashers provide low shear and long residence times. Open dashers are used to produce ice cream, a longer residence time helps to achieve good aeration.  

Closed one with the same outlet temperature and throughput. Closed dashers are used when low throughput is required or for ice creams that need to retain their shape after extrusion. Higher shear increases the amount of coalesced fat, thereby stiffening the ice cream.

Approximately 4 degrees Celsius ice cream mix is pumped from the ageing tank to the barrel. In order to make quality ice cream, bubbles must disperse throughout the cream. When the dasher beats, it shears the large air bubbles into many smaller ones; the greater the applied shear stress, the smaller the air bubbles become 

Some microorganisms are killed by freezing, while others are stopped from reproducing and producing toxins when frozen. The mix should certainly contain live bacteria after pasteurization.

Normally, ice cream leaves the factory freezer at about half of the typical temperature of 18 degrees Celsius, so it’s very soft when it leaves. Simply storing ice cream at the factory freezer exit temperature will cause it to deteriorate very quickly

Basically, the size of ice crystals increases and the total number decreases as the temperature rises, so in order to avoid deteriorating the microstructure, fruit, chocolate, cones, and ice cream should be combined. Before ice cream can be assembled, it needs to be either harder or colder depending on the product 

The temperature of the ice cream is lowered as quickly as possible after it leaves the factory freezer, this is known as hardening The factory freezer gets the ice cream into the conveyer belt after it’s been hardened in the hardening tunnel. Cool air is blown over the ice cream cream, lowering the air temperature and increasing the airflow

And the ice cream gets to the truck where freezer systems are properly checked 

Enjoy your ice-creams!!!