Gelato

A short story

1. Origins: cooling with ice and snow
2. Discovery of water properties
3. Ice and salt
4. Invention of gelato machine
5. Development of mechanic refrigeration

1. Origins

Snow and ice used for cooling food and drinks since the 4000 B.C. in many parts of the world. From Mesopotamia to China, from Persia to Europe we have trace of the use of ice from the mountains collected during the winter and used during the summer.

 

Ice or snow were put in direct contact with the food to cool. 

2. Water cooling

The "invention" of the thermometer by Galileo brings cooling to a new era.

 

The discovery of the fact that salts dissolved in water decrease its temperature is the first step for the development of gelato. 

 

Only with water and salts it's possible to freeze a "sorbet", first evidence on Arabic books of the 13th century.

3. Ice + Salt

In 1589, Giambattista Della Porta discovers that adding salts to ice instead of water can reach even lower temperatures. 

At this point the first gelato like we know it today is born and recipes of this dessert quickly start appearing. This cold dessert spread among the European aristocracy.

 

It is soon discovered the importance of mixing while freezing to reduce the dimension of ice crystals. 

4. Gelato machine

At the beginning of the 19th century gelato is already popular for a wider audience. It is served in cafes and restaurants among europe.

 

In 1843 Nancy Johnson patents the first machine, this allows the production of bigger quantities.

5. Refrigeration 

Until the 20th century refrigeration needed a natural source of ice. 

Gas expansion refrigeration opens the road to the modern age of gelato. 

 

In 1927 Clarence Voght invents the continuous freezer. (Horizontal instead of vertical cylinder)

Pasteurization and homogenization are introduced.  

What is gelato?

What is gelato? 

Heterogeneous mix

3 phases

1. Liquid phase: sugar solution (matrix)
2. Gas phase: air bubbles
3. Solid phase: ice crystals, fats, fibers and other solids

 

Complex colloidal system

What is gelato? 

Complex colloidal system

1. Sol is a colloidal suspension with solid particles in a liquid. 
2. Emulsion is between two liquids.
3. Foam is formed when many gas particles are trapped in a liquid or solid. 

What is gelato? 

Interphases

 

In a system with more than one phase we always have interphases, the zones or surfaces of separation between 2 different phases. 

 

Interactions of interphases determine the stability of the system.

Gelato or Ice Cream? 

Gelato and ice cream can be the same thing, but it depends on the country and on the regional regulation. 

Often "ice cream" is used to indicate the industrial product whilst "gelato" is used for the artisanal italian dessert.

 

Other popular words: Helado, Ijs, Eis, Glace, Lody.  

Gelato

• Fresh ingredients
• Served fresh
• Slow churning
• Low overrun (10-35%)
• Intense flavour
• Stored for short time

Ice cream

• Dried ingredients
• Stored for months
• High speed churning
• Inflated air
• High overrun (70-150%)
• Aromas to give flavour

The world of frozen desserts 

Gelato: italian style ice cream

Sorbetto: fruit gelato without dairy products

Industrial ice cream: continuous freezers

Soft serve: high overrun, semi-continuous freezer

Granita: no overrun, bigger ice crystals

Cremolata: high fruit content, no overrun

Popsicles/water ices: on a stick or in a tube, no air

Gelato on a stick: with or without air

Semifreddo, parfait...

 

The world of frozen desserts 

Gelato

Production: vertical or horizontal batch freezers

Ingredients: milk, cream, eggs, sugars, flavourings

Overrun: 10-35%

Served in balls or in italian style with scoopers

 

The world of frozen desserts 

Sorbetto

Production: same as gelato

Ingredients: fruit, water, sugars, (egg white)

Overrun: 10-25%

Served like gelato

 

The world of frozen desserts 

Granita

Production: vertical (or horizontal) batch freezers

Ingredients: fruit, water, sucrose

Overrun: 0%

Served in glasses to eat with spoon or straw

The world of frozen desserts 

Cremolata

Production: vertical (or horizontal) batch freezers

Ingredients: same as granita but with higher fruit content

Overrun: 0%

Served in glasses with a spoon

 

 

The world of frozen desserts 

Industrial ice cream

Production: continuous freezers

Ingredients: (powdered) milk, cream, eggs, sugars, flavourings

Overrun: 30-150%

Packaged in different shapes

 

The world of frozen desserts 

Soft serve

Production: horizontal semi-continuous freezers

Ingredients: milk, cream, eggs, sugars, flavourings

Overrun: 40-70%

Served in cups or in single portions desserts

 

 

The world of frozen desserts 

Popsicles/water ices

Production: static freezing

Ingredients: water, sugars, flavourings

Overrun: 0%

Packaged on sticks or in tubes

 

 

The world of frozen desserts 

Gelato on a stick

Production: dynamic + static freezing, static freezing

Ingredients: milk, cream, eggs, sugars, flavourings

Overrun: 0-70%

Served on sticks

 

The world of frozen desserts 

Semifreddo: white egg based frozen dessert with 50% of air

Bomba gelata: gelato outer layer, semifreddo egg yolk based inside

Parfait ghiacciato: pate a bombe + whipped cream

Biscotto ghiacciao: similar to parfait but with italian meringue 

Soufflé ghiacciato: like biscotto with more meringue, served in the typical soufflé cups

Semifreddo all'italiana: crema pasticcera + italian meringue + whipped cream (heavier, richer in taste and creamier)

Mousse ghiacciata: mousse with more italian meringue, italian meringue + flavouring + whipped cream

 

Gelato production (intro)

Traditional artisan production

1. Sourcing of ingredients
2. Pasteurization
3. Aging
4. Characterization 
5. Freezing
6. Hardening
7. Expo and sell

1. Sourcing of ingredients

1. Gelato is the result of the choice of the raw ingredients
2. Choice of safe and excellent raw ingredients is determinant for the end product.
3. How to source ingredients?

2. Pasteurization 

1. Mixing and thermal cycle of the ingredients.
2. Pasteurization temperature will depend on the type of mix.

3. Ageing

• Ageing lasts between 6 and 12 hours for optimal result
• In this phase the mix is slowly stirred and kept at 4°C
• Several processes occur during this phase:
  - proteins hydration
  - viscosity increase
  - fat displacement

4. Characterization 

Flavouring are added to the base mix. 

5. Freezing

1. Liquid mix is transformed into the final product.
2. The mix is continuously stirred and heat is subtracted, this part is the most important for the final texture and structure.

6. Hardening

• In this phase the liquid water is transformed in to ice the fastest possible to obtain small ice crystals.
• The process takes place in a blast chiller with air at -40°C
• If the destination is the showcase it will stay for 10-15 minutes
• If the destination is the freezer cabinet it will stay for 2 hours before being stored at -18°C

7. Display and sell or storage

Display and sell

• Gelato is put in the showcase between -10°C and -16°C
• The gelato can stay 1 to 4 days in the showcase before it start losing its texture and sensory features.

 

Storage

• Storage in cabinets at -18°C
• Storage for at least 4 weeks

Gelato production methods

Traditional method: pasteurization + aging + freezing

Combined method: pasteurization (thermal shock) + freezing

Hybrid method: pasteurization + combined method

Gelato machines

Vertical: the traditional machine

Horizontal: modern machine inspired by the industrial freezer

Combined machine: pasteurizer and batch freezer together

Vertical machine

Horizontal machine

Combined machine

Raw ingredients 1 

A typical mix of gelato is based on milk, cream, sugars, sometimes eggs, functional ingredients (milk powder, proteins, stabilizers), and characterizing ingredients (pistachio, chocolate..)

R.I. 1 - Water 

Water is in most of the ingredients used in gelato production. Milk is composed by over 90% of water and cream by 60%.
Moreover is the main ingredient in the productions of fruit sorbet.

 

When used water must be drinkable, with a very good taste and possibly not too hard (low mineral content).

R.I. 1 - Milk

Milk is the first ingredient that is associated with gelato. Can be of cow or of other animals, it's rich in proteins and low in fat. 

Fresh whole milk: usually cow milk, the most used for gelato

Whole milk powder: sometimes used in gelato when fresh milk is not available. Fat rancidity is a big problem.

Skimmed milk powder: widely used in gelato as functional ingredient. It is a good source of proteins (and solids) that help overrun and give a smother and warmer structure. 

R.I. 1 - Sugars

Sugars are the cheapest source of solids and they have 2 main functions in gelato: lowering the freezing point and increase sweetness and flavor. 

Most used sugars are: 

Sucrose, Dextrose (D-glucose), Glucose syrup, glucose syrup dry, Fructose, Maltodextrin, inverted sugar...

R.I. 1 - Sugars - Sucrose

It's the most common sugar and the main sweetener in a recipe. The main sources are sugar cane or sugar beet. Other sources includes palm flowers, and fruit. 

It as a sweet neutral taste and in to some extent increases and improves the taste of other ingredients. 

Very soluble in water, its solubility is proportional to the temperature of the solute. 

R.I. 1 - Sugars - Dextrose

It's the sugar our brain use to function. A monosaccaride is usually produced by enzymatic hydrolyses of a complex carbohydrate, usually corn starch. It's also present in most of the fruit. 

It's white with a clean taste and highly soluble in water. It is less sweet than sucrose but lowers the freezing point more therefore a gelato only with it would be too cold and glossy.

Usually replace sucrose of 25-30%. 

R.I. 1 - Glucose syrup

It's a mix of complex and simple carbohydrates (glucose, maltose, oligosaccharides), since the hydrolysis of starch was not complete.  

The hydrolysis can reach different levels and to indicate the level of it a unit called Dextrose Equivalence (DE) is used that indicates the percentage of reducing sugars in the mix. 

It's less sweet than sucrose and with a lower freezing point depression power. It helps getting a more viscous and warm gelato.

 

R.I. 1 - Glucose syrup dry

Same product as glucose syrup but dehydrated. It's therefore more used in gelato for the ease of storage and use. 

 

R.I. 1 - Fructose

Another simple sugar that is mostly found in fruit. Similar characteristic of dextrose but with higher sweetening power and a different after taste.

Industrially can be obtained by starch and sometimes from fruit with a much higher cost. 

Often used to market products without sucrose, or in fruit sorbet, but it doesn't have any proved health benefit.

 

R.I. 1 - Maltodextrin

It's a glucose syrup dry, hence a mix of different carbohydrates with a high content of complex carbohydrates (low DE, <20). 

Low sweetening power and freezing depression power. 

Mostly used to increase viscosity and reduce re-crystallization.

Usually at 2% in gelato, but can be more to lower the sweetness. 

 

R.I. 1 - Inverted sugar

It's a sugar syrup with water, glucose and fructose. Sweeter than sucrose has the freezing point depression power of its constituents. 

It's the product of the acid splitting of a sucrose solution, later neutralized with sodium bicarbonate. 

Widely used in the past when industrial glucose and fructose were not easily available.

 

R.I. 1 - Honey

It's a natural inverted sugar. The inversion process is made by the bees. 

It was the first sweetener used to make gelato. 

It has a strong characteristic flavor, for this reason is usually used for it's aromatic properties. 

R.I. 1 - Lactose

The only sugar of animal origin. Composed by glucose and galactose bond together. 

It's not functionally very useful in gelato because it is poorly soluble and crystallize easily during freezing giving a typical sandiness feeling in gelato. It is not added "on purpose" but it's present in all dairy products.

It has a very low sweetness and the same freezing point depression power of sucrose.

Cream

It's a milk by-product that collect milk fats. 

Thanks to its pleasant and fresh taste it's the biggest source of fats in gelato. 

There are different types of cream on the market, for gelato usually a cream with around 35% of fat is used.

Eggs

In the past chicken eggs, specifically the egg yolks were a widely used ingredients in gelato production because of the proteins and lecitin in the yolk that improve the structure of the gelato.

Nowadays is less used because of the tendency to prefer a lighter gelato. Egg yolk also brings a strong flavor that is not always appreciated.

It can be found as fresh eggs or pasteurized egg yolks, with or without added sugar.  

Cacao

Processing the seeds of the fruit of cacao plant we have 3 main products on the market: cacao powder, chocolate and cacao massa.

All of them can be used in gelato to make one of the most popular flavors.

Cacao is a versatile ingredients and very appreciated.

Stabilizers 

Often called "neutro" or "nucleo", it's usually made by 2 components: thickening agents and emulsifiers. 

It is used to increase the viscosity of the mix, to "emulsify" fat and air particles and to increase stability for more than 24 hours. 

The amount used is usually of few grams per kg of gelato mix.

It can be for "cold use" or "warm use". 

Powdered bases

One of the top products of the gelato ingredients industry. 

They can be complete or to add to the mix with other sugars. 

They usually contain stabilizers and a mix of sugars and sometimes milk powder and proteins.

They can also contain aromas and colors.

They are used to speed up the production but they have a high cost. 

Characterizing ingredients

All the ingredients that give a specific flavor to gelato are in this category. 

There are many types of ingredients, virtually anything can be used in gelato. 

The amount of these ingredients depends on a personal choice, usually they are 5% to 25% of the mix. 

Gelato paste

They are processed raw ingredients ready to use. 

They can be pure or with more ingredients, usually sugars and sometimes aromas and colors. 

They can be of fat prevalence or of sugar prevalence. 

All those processed raw ingredients can be processed in created in the gelato lab as well. 

Examples: pistachio and nuts, tiramisù, amaretto, mint, coconut...

Fresh fruit

Fresh fruit is one of the best ingredients. Fruit must be in good state, possible let ripe on the plant and at completely ripe but not over ripe. 

It's necessary to properly wash fruit and remove peel when needed and all non edible parts. 

Frozen fruit

It's fresh fruit that has been cleaned and frozen with or without additional sugar. 

It's available the whole year but it requires a careful control of quality and ripening stage.

Frozen fruit puree 

Like frozen fruit but usually already at the best stage of ripening, it's already blended but often contains additional sugars for better preservation. 

Fruit pastes

They are sugar based paste, similar to jam, usually very sour because of citric acid. They hardly can be a substitute of fruit but they are often used to increase the taste and color of fruit gelato or sorbet.

Recipe formulation

Granita

What is granita made of? 

Granita is the simplest form of gelato, it's usually made of water, sugar, fruit or other flavorings like coffee of chocolate.

 

In the process there is almost no air incorporated and the result is cold and crystals are coarser than in gelato. 

Fruit granita

Fruit: 5%-30% 

Total sugars: 14%-22%

Water: 50-80%

Fruit:

Strong fruit (lemon, lime): lower %
Medium fruit (peach, strawberry..): average %

Weak fruit (watermelon, oranges..): high %

Nuts granita

Nuts: 5%-15% 

Total sugars: 14%-22%

Water: 60-80%

Nuts:

Raw or roasted

In paste or with coarse particles

More granita types

Coffee/Chocolate/mint

Total sugars: 18%-22%

 

Tips:

Coffee can replace completely water.

Cacao or chocolate better heated. 

Coffee granita

Coffee: 80%

Total sugars: 20%

 

Tips:

Coffee also contains fat and proteins that help air incorporation. For this reason coffee granita is one of the most difficult to make. 

Lemon granita

Lemon: 20% (Lemon=5% sugars)

Total sugars: 20%

 

Strawberry granita

Strawberry: 30% (Strawberry=? sugars) refractometer

Total sugars: 18%

 

The gelato lab

The gelato machines

Traditional method:

• pasteurizer + aging + batch freezer
• pasteurizer + homegenizer + aging + batch freezer
• pasteurizer + batch freezer

Thermal shock method:

• combined machine
• pasteurizer + combined machine

Traditional method

Pros:

• ease of production of big quantities
• better resistance to temperature change with aging
• ease of creation of many different flavors

Cons:

• more machines to buy and more space to have
• flavors more similar to each other
• risk of wasting products in case of blackout or errors

Thermal shock method

Pros:

• only one machine (or possibility to add a pasteurizer)
• ease of better hygienic protocols
• every flavor its own recipe 
• lower water and electricity consumption

Cons:

• more time spent weighting ingredients
• mix does not age
• better organisation required

Other facilities 1

Working table

• Inox (stainless steel) table, can have space for sugars or other ingredients on the bottom.
• Important to check the inox type and quality.
• Minimum dimensions 140x80cm

Inox 2 basins sink

Taps according to regulation and to convenience  

Other facilities 2

Dripping desk

• Inox (stainless steel) 
• Important to dry washed tools
• Can be above the sink or beside

Washing machine (optional)

Not necessary but can be useful to speed up cleaning

Other facilities 3

Fridge cabinet +4°C

• To store fresh ingredients (milk, cream, eggs, sauces...)
• Min 700l

Freezer cabinet -18°C

• To store gelato and frozen products
• Min 900l

Freezer cabinet -14°C (optional)

• Step between storage and showcase

Other facilities 4

Blast chiller (optional but useful)

• To improve quality of gelato that is stored
• To stabilize gelato before serving
• Useful when making other products like gelato cakes, popsicles, single portions...

 

Dimension depending on the number of flavors in the showcase. 

Blast chiller

Other facilities 5

Shelves and storage space 

• inox
• to store ingredients and tools

Cart for sugar bags

To manage 25-30 kg bags of sugars

Other tools 1

• Electronic scale (min 15 kg with 0.1 g step)
• Immersion blender
• Lemon squeezer
• Juice extractor (optional)
• Microwave (optional)
• Stand mixer (optional, for pastry preparations)
• Spatulas
• Whisk 
• Knives

Other tools 2

• Sieve
• Cutting boards
• Induction plate
• Pots and pan for induction plate
• Plastic or inox barrels
• Bowls for fruit and sugar
• Barrel for machine cleaning.

The showcase 1

• It's the center of the selling activity, a lot of attention must be given to this part of the shop.
• It must be easy to reach for the client that need to choose
• Position flavors in categories (creme, sorbets, granite, low sugars..)
• More fruit sorbet in the summer, less in the winter
• How many flavors depend on personal choice and on the market
• Don't change completely the order to confuse returning customers

The showcase 2

• The gelato must look attractive, don't exaggerate with decoration. Use only edible decoration.
• Try to use contrasting colors to get an attractive disposition
• Do not put labels inside the gelato, it must be visible and effective.

The showcase: traditional

The showcase: modern

The showcase: hybrid

Static showcase

• easy to maintain
• simple mechanics (reliable)
• cheap
• low energy consumption

 

• no air circulation
• temperature gradients
• reading temperature much different from gelato temp
• gelato less visible

Dynamic showcase

• air circulation system
• prevents warm air to enter when opened
• better temperature control inside
• good gelato visibility

 

• bigger compressor
• more expensive
• more energy consumption

The serving scoop

Complementary products

Management of a gelateria

The product is nothing without the box.

Environment:

The customer must feel comfortable and welcomed

• Use enough light to create a bright environment
• Good ventilation of the environment
• Keep showcase and serving space clean from gelato pieces
• Clean frequently all glass surfaces
• Clean the dust often
• Frequently empty trash bins

Management of a gelateria

Catching the customer

• Clean area outside the shop
• Don't leave full trash bins outside
• Take care of the space in the proximity of the gelato shop even if not of property
• Provide facilities for the customers (to park bikes, for dogs...)

Management of a gelateria

Selling staff

A good part of the perception of the gelato shop depends on the quality of service. 

Whoever serves the gelato must follow a company protocol on look and behavior. 

Management of a gelateria

Staff look 1

The first impression is communicated by the look of the selling staff. It's important to give the best first impression.

• Hands and nails must be clean and curated.
• Beard must be curated
• Better to use a hat or similar
• Keep the uniform clean always
• Always keep a change of cloth ready

Management of a gelateria

Staff look 2

• Shoes must be clean
• Never use hands in place of tools
• Do not touch food directly with hands in front of customers
• Do not touch "dirty things" and food without washing hands or putting gloves
• Gloves do not change the behavior
• Always check the look

Management of a gelateria

Staff behavior 1

• Smile always, it's the best welcome
• Welcome the customer arriving and leaving
• Call the client by name if known 
• Try to remember the habits of the customer
• Look at the client when needs attention, don't do other things and "keep listening"
• In case of waiting let the customer understand he will be served soon

Management of a gelateria

Staff behavior 2

• Don't wait still and without saying anything, waiting for the customer to talk
• Don't be fake
• Try to judge the work from a customer perspective
• Keep conversations on happy topics with customers
• Don't be intrusive
• Keep calm also when the shop is busy 
• Try to make use of customer complaints 

Management of a gelateria

Staff behavior 3

• Stressful situation should be faced with calm
• Giving a free tasting usually means selling something
• Try to propose the tasting of new or special flavors
• Don't look annoyed by the indecision of customers
• When there is nobody don't stay sill on the showcase, stay active cleaning or take a rest elsewhere if needed
• Do not eat or smoke in front of customers
• Smile and thanks when the customer pays

Management of a gelateria

Gelato

• Always check the freshness of gelato and try not to offer an old or not satisfying product
• Prepare the shop for the busy moments:
• Ordered and clean
• Gelato in good conditions and full showcase
• Serving scoops clean and one for flavor
• Napkins available
• All disposable ready to be used

Recipe formulation

The sorbet

Sorbet - Sorbetto

• No milk or dairy products
• Direct method or sugar syrup method
• Fruit based 

Can be done with other ingredients than fruit but it will go in another category (chocolate, nuts sorbets...)

Fruit sorbetto

Total sugars: 26-32%

 

Fruit: 10-60%

 

Water: 15-65%

 

Total solids: >30%

Fruit 

Strong fruit: 5-30%

(Lemon, lime, cedar)

Medium fruit: 30-50%

(Apricot, peach, mango, melon, berries...)

Mild fruit: 55-65%

(Watermelon, oranges, tangerines, papaya...)

Lemon juice

• It balances sweetness
• It reduces oxidation (keeping the colors vivid for longer)

 

Quantity depends on personal taste and type of fruit.

Around 1%  

Sugars

• Sucrose
• Dextrose
• Glucose syrup dry/maltodextrin

 

Total sugars: 27-30%

Stabilizers

Total: 0.2-0.5%

 

(Neutro, tara gum, guar gum, xanthan, carrob,....)

Peach 40%

Sugar syrup

Sugar syrup at 50% or 70%. 

• Water 
• At 30°C add sugars
• Pasteurize at 85°C
• Stop and preserve at 30°C

Sugar syrup 50%

Fruit: 15-50%

Sugar syrup: 50%

Water: 0-35%

Lemon Sorbet

Lemon: 15%

Sugar syrup: 50%

Water: 35%

 

Total sugars: 26%

Mango Sorbet

Mango: 40%

Sugar syrup: 50%

Water: 10%

 

Total sugars: 30-31%

Water and ice

Melting ice

Freezing water

Solute in water

• Boiling temperature increase
• Freezing point depression
• vapor pressure change
• osmotic pressure change

Freezing sugar solution 12%

Ice in gelato

• The amount of ice in gelato depends on the temperature.
• While the ice forms the sugar solution get more concentrated and the freezing point of it keep decreasing. 
• With a small amount of ice is important to avoid temperature fluctuation.
• Also the other ingredients in the mix are more concentrated: sensory attributes change.

The typical amount of frozen water for a scoopable gelato is around 75%

Freezing curve

Sugar solution 3%

Ice in gelato 

More frozen water means harder gelato.

Less frozen water means softer gelato.

 

The formation and distribution of ice crystals also depends on:

- mix composition 

- processing condition (freezing)

Ice in gelato: mix composition 

Composition with more available water will tend to have bigger ice crystal size.

High molecular weight solutes prevent water molecules from moving hence decrease re-crystallization.

Ice in gelato: processing 

The faster the freezing and the lower the temperature, the smaller the crystals.

Avoid temperature fluctuations. (Size distribution)

Re-crystallization

Ostwald growth:

temperature fluctuation driven

 

Accumulation or agglomeration:

mechanically and kinetic driven

Re-crystallization: Ostwald

Air in gelato

Air in gelato 

Often not taken in consideration, big influence on the sensory attributes of gelato.

 

Overrun: % of volume increase from initial mix to finished gelato.

Air quality

Usually the air is taken directly from the atmosphere.

• Micro-organisms in the air
• Air contamination from people or machines operating in the space
• Presence of insects that can contaminate air
• Pollution and dust

Air bubbles

In the gelato formation air bubbles forms first with a big size and with agitation are split into smaller bubbles.

Size distribution from 1 to 80 micron.

Average bubble size in finished gelato: 20 micron.

 

Overrun during mixing changes with temperature.

Overrun during mixing

Carbohydrates

Carbohydrates

• Monosaccharides (polymerization 1)
• Oligosaccharides (polymerization 2-10)
• Polysaccharides (polymerization >10)

 

- Sweetness 

- Regulation of frozen water

- Viscosity increase (stability and microstructure)

Solubility in water

Solubility with temperature

Sweetening power

Most of carbohydrates have some sweetening power.

Sweetening power depends on:

- Chemical form of molecules

- Time of solution

- Concentration

- Temperature (fructose)

 

Sweetening power

Sweetening power is measured experimentally and referred to sucrose. Usually called sucrose equivalence.

Perception of sweetness is influenced by factors like:

- emotional conditions of the person

- color

- temperature

- age

- noise

- ....

 

Sweetness in gelato

POD or SE

Sucrose: 100

Other sweeteners refer to sucrose.

 

Sweetness in gelato highly depends on geographic location, habits, ... so it must be adjusted accordingly.

 

Good starting point for gelato 160-180 and for sorbet 230-250

Freezing point depression

PAC: relative freezing point depression power (compared to sucrose)

Depends on molecular weight of the ingredient. 

Not only carbohydrates act on freezing point depression in gelato (salts, minerals, some acid compound in fruit..)

Freezing point depression

Stabilizers

Usually polysaccharides, nutritionally soluble fibers.

Usually of plant origin.

In Europe classified as additives (E....)

Increase the viscosity of water at low dosage (0.2%)

Can interact with each others. 

Can be soluble at cold or warm temperature.

Can change their properties with temperature and ph.

Stabilizers in gelato

• Give smooth texture
• Prevent melting
• Prevent air loss
• Reduce ice crystal growth
• Increase overrun

Stabilizers in gelato

• Sodium alginate
• Carrageenan
• Locust bean gum
• Guar gum
• Tara gum
• Pectin
• Xanthan
• Gelatin
• ..... new stabilizers

• Sodium alginate
• Carboxmethil Cellulose
• Cullulose
• Arabic gum

Emulsifiers

Surface active molecules. 

Destabilization of fats, bonds between interphases. 

They actually de-emulsify some of the fat creating partial coalescence (fat globules clusters), these clusters help stabilize the air bubbles by preventing their coalescence. 

If too much emulsifiers are used and too much fat is de-emulsified, fat globules coalescence will create too big fat particles.

Emulsifiers in gelato

0.3%

• Mono-/diglycerides (from vegatable fats hydrolyzation)
• Esters of sucrose
• Lecitin (egg yolk contains 9%)
• Polysorbate 80

Gelato formulation

Ingredients

Milk

One of the best ingredients for gelato, for sensory attributes and functional properties.

It's the main source of water in gelato.

 

Average composition:

3.5% fat

3.5% proteins

4.0% sugars

1% other solids (minerals, vitamins, ferments...)

Skimmed Milk powder

Most used in gelato to increase the total solid content and for the properties of the proteins. They bind water and increase stability and overrun.  

Spray dry - Drum dry - Freeze dry

Average composition:

1% fat

37% proteins

51% lactose

3% other solids (minerals, vitamins, ferments...)

Whey proteins and casein

Can be added in gelato to improve the stability, increase overrun and prevent melting.

They are also partly responsible for the milk flavor.

 

Whey proteins (lactoglobulin, lactalbumin,...) can be find at 80% or more purity.

 

Casein can be found alone as "milk protein isolate".

 

Cream

Centrifuged cream has the best sensory attributes.

It's the best source of fats for gelato.

 

Best average fat content for gelato: 30% to 40%

 

Can be used whipped on top of gelato. (Manual whipping, cream machine, siphon) 

Butter

At least 80% of fat.

 

Can be produced by cream as a by-product of cheese or from centrifugation (better flavor). 

 

Fat globules are bigger hence homogenization is recommended. 

Other fat sources

• Nuts, cacao
• Palm oil
• Coconut oil
• Margarine 
• Soy oil
• Peanut oil

Different fats have different melting points, or melting profile.

Fat in gelato

• Improve the overall flavor of gelato
• Give a soft and short structure
• Give body to the gelato
• Regulate the melting balance in the mouth
• Decrease cold feeling 

Too much fat can decrease too much the cold feeling usually wanted in gelato.

Alcohol products

• Lower the freezing point and destabilize gelato.
• Denaturate proteins
• Can prevent the activity of stabilizers and emulsifiers

Till 5% of alcohol not too many problems, better to use fibers and high molecular weight carbohydrates for better stability.

 

Add the alcohol product when gelato has already reached -3°C in the batch freezer.

Coffee

In gelato coffee can be used in different ways:

- Liquid coffee

- Instant coffee

- Coffee beans in infusion with milk and/or cream

- Powder directly in the mix

- Combination of the previous methods

Eggs

Egg white: water 88% and proteins 11%

Egg yolk: water 50% proteins 17%, Fat 32%

 

Both part of the egg can be used in gelato but usually egg yolks are more interesting for their flavor and the emulsifying properties. 

 

In gelato egg yolks from 1% to 12%.

Cacao

Mostly fat and non-soluble fibers.

In gelato can be used:

• Cacao powder (10/12 or 22/24, % of fat)
• Cacao massa
• Chocolate

Cacao for better dispersion and flavor is usually heated up to 92°C.

Nuts

Walnut, hazelnut, almond, pistachio, macadamia, pecan, pine nuts, peanuts.

 

Can be used raw or roasted. Roasting and refining can bring to very different results. 

 

Typical use: 5% to 15%

 

Fresh herbs

Fresh herbs, flowers and leaves can be used in gelato in different ways:

• Blended in the mix
• Infusion (cold or hot)

The amount highly depends on the type of ingredient used, can vary from 0.1% to 5%. 

 

Spices and dry roots

Can be used whole in infusion or powdered directly into the mix.

Hot infusion:

5 minutes to few hours, usually in water

Cold infusion:

6 to 24 hours, usually in milk or gelato mix

The amount highly depends on the type of ingredient used, can vary from 0.1% to 2%. 

 

Gelato formulation

Temperatures

Pasteurisation

High pasteurization: 92°C (for chocolate)

 

Medium pasteurization: 85°C (for milk or egg base)

 

 

Gelato extraction T

Highly depends on the recipe and on the amount of frozen water wanted.

 

From -4°C to -12°C

 

 

Gelato serving T

Highly depends on the recipe and on the amount of frozen water wanted.

 

Between -8°C and -14°C.

 

Attention:

The temperature set on the showcase will be 3 to 8°C lower than the temperature of gelato!

 

 

Gelato recipe formulation

The gelato formulation

Sugars: 14-24%

Fats: 3-12%

SML/MSNF: 6-12%

Other solids: 0.5/5%

 

Total solids: 32-42%

Water: 68-58%

Base bianca

Hazelnut

Original base

How to solve the problem?

• Make an "unbalanced" base higher in sugars for oil paste
• Adjust the final recipe adding sugar

 

With the combined method each recipe is balanced on its own.

Fruit based gelato

Fruit content: 25-35%

 

To add to white base and add ingredients to adjust the formulation parameters (cream, milk, sugar)

 

Follow the formulation rules for milk based gelato.

Recipe formulation

Vegan gelato

Vegan gelato

• Presence of fat and proteins
• No dairy products or eggs

 

Water: from water, plant based "milks" (soy, rice, cereals, chufa...)

Fat: from characterizing ingredients or added vegetable fat

Proteins: from characterizing ingredients or added 

Sugars: normal formulation

Vegan gelato problem

Using the normal formulation method and not adding dairy products we have a deficit of sugars and total solid: no lactose, and lower proteins. 

 

Possible solutions: 

• Increase total sugars (up to 30%)
• Use fibers (2 to 8%)

Cocoa sorbet

60 g Cocoa powder

584.5 g water

3 g stabilizer

45 g dextrose

65 g maltodextrin

190.76 g sucrose

51.74 g inulin

Functional ingredients

Fibers

Fibers in gelato

• Provide a source of solids
• Don't bring sweetness to gelato
• Can partially replace sugars
• Can act as fat replacer
• Increase mix viscosity and stability
• Low caloric content
• Healthy ingredient
• Most fibers are not labeled as food additive

Fibers in gelato

Inulin: different types of purity and chemical composition, typical use 0.5% to 5%

Polydextrose (E1200): typical use 2% to 6%

Baobab fibers: brings some of the fruit flavor, better to use in fruit, typical use: 1-2%

Citrus peel fibers: retain a lot of flavor from citrus, typical use 0.1% to 2%

Novelty products: neutral flavor, non additives, different type of natural sources, typical use: 1% to 7%

Variegati

Variegato

Flavors where some ingredients is added after gelato is ready.

 

• Chocolate
• Fruit sauces or jam
• Nuts, biscuits...
• Other sauces

Sauces

Fruit, chocolate, eggs, nuts.. 

Can be used on top of gelato for variegato or to add to a base to characterize it.

 

Total sugars: 25-40%

Stabilizers 0.1-1% (no emulsifiers in sauces!)

 

For water based syrups (infusions...) total sugars: 40-60%

Egg sauce

To characterize a white base with eggs.

 

 

Chocolate sauce

To characterize a white base with eggs.

 

 

Raspberry coulis

Mix all ingredients except lemon, heat to 65°C or to 98°C (depending on de density wanted) then add lemon juice and cool down.

 

Gelato flavors

Italian traditional flavors 

• Fiordilatte/Fior di panna
• Stracciatella
• Crema
• Hazelnut
• Pistachio
• Walnut
• Almond
• Coffee
• Tiramisù
• Zabaione 
• Mint (with chocolate chips)
• Chocolate
• Gianduja
• Bacio (chocolate with whole hazelnuts)
• Chocolate with fruit (orange, berries)
• Chocolate with coffee or liquors

• Yogurt 
• Cremino (variegated with nut pastes)
• Ricotta
• Mascarpone
• Honey
• Cookies 
• Cheesecake
• Amaretto (apricot almond - liquor)
• Liquorice
• Nougat 
• Rice cake
• Saffron
• Cassata (ricotta and candied fruit)
• Malaga (rum soaked rosins)
• ...

Indian flavors?

Kulfi:

• slowly evaporated mix
• high protein content
• high lactose content
• lactose partially caramelized 

 

Flavors:

• Sandalwood (chandan)
• Indian basil (Tulsi)
• Saffron pistachio
• Almond and figs
• Paan
• Tamarind
• Litchee
• ....

Machine manufacturers 

• Carpigiani
• Cattabriga
• Bravo
• Valmar

Showcase manufacturers 

• FB
• ISA
• IFI
• Frigomeccanica
• Gelostandard

Bibliography

Ice cream science

• Ice cream (7th edition), H. Douglas Goff , Richard W. Hartel 
• The science of ice cream, C. Clark
• Fundamentos cientificos de la heladeria, J. Mora, S. Maestre

Gelato books

• Sorbetti e gelati, A. Grasso
• Scienza e tecnologia del gelato artigianale, L. Caviezel
• Il gelato artigianale italiano, D. Panciera
• Avanguardia Gelato, Paolo Brunelli, Gianfrancesco Cutelli, Alberto Marchetti, Andrea Soban