Overview

Cream is produced by the centrifugal separation of milk.  During separation, two streams are created, a highly concentrated milk fat stream termed cream and a non-fat stream of skim milk that can be further processed into evaporated or dried milk products.  The fat content of the cream resulting directly from the separator typically ranges from 35-45%.  Creams of different fat levels can be produced by standardizing (addition of a low fat stream to a higher fat stream to achieve a desired fat level) with skim milk.  Higher fat creams can also be produced by further separating the high-fat stream (these creams are usually industrial products).

Once the cream has been standardized to the desired fat level, it is pasteurized or ultra high temperature (UHT) pasteurized to ensure that it is free of pathogenic bacteria.  Depending on the cream type, it may also be homogenized.  

Creams are oil-in-water emulsions and therefore when it is standardized to various fat levels with skim milk, it must be homogenized to reduce the fat globule size to increase the stability (prevent fat separation).  Proteins from the milk migrate to the fat globule membranes to act as emulsifiers.  During homogenization, various grades of viscosity in cream products can occur.  Usually, lower pressures are used than those used for milk products.  High fat whipping cream is not normally homogenized (unless UHT pasteurized), due to the excessive viscosity created and degraded whipping functionality.  On the other hand, homogenization of high fat cream is utilized in the production of spoonable whipped cream products used as dessert toppings.  Homogenization is conducted for UHT pasteurized whipping cream in order to prevent fat separation which increases with UHT pasteurization.  Stabilizers such as mono-glycerides are added to improve whipping ability. 

Composition

• Typical compositions of cream varieties are as follows:

In terms of microbiological quality, cream has basically the same standards as those required for ordinary milk products.

Characteristics

Appearance and Flavour: Cream should appear white to off-white with smooth consistency and varying degrees of viscosity depending on the fat content (typically increased viscosity as the fat content increases).  Cream should be homogeneous without separation.  The flavour and odour of cream should be rich, clean and sweet with no off-flavours.

Storage: Cream should be stored at refrigeration temperatures (4-7°C) in a closed container.  The typical shelf life of pasteurized cream is one to two weeks and a few months for UHT pasteurized cream.  However, once the container of UHT pasteurized cream is opened it should be treated as pasteurized cream.  As cream ages, its lactic acid content increases and can result in curdling.  Freezing destabilizes the oil-in-water emulsion of creams and therefore the fat will separate upon thawing.  Separated cream cannot be used for whipping, but can be used in products such as “cream soups” where flavour is the critical factor.

Varieties: There are a whole range of creams based usually on the milk fat content. For industrial purposes, creams can be produced at specific fat levels, however availability is dependent on the volume usage. Provincial legislation governs the retail and foodservice creams in the market. In Ontario the common cream products and their regulated compositions (Milk Act) are:

• Half-and-Half: shall contain not less than 10% milk fat and is pasteurized or UHT pasteurized and homogenized.  Termed half-and-half as it is a mixture of milk and cream usually in equal parts.  Half-and-Half cream may also contain pH adjusting agents and stabilizers.
• Table Cream: shall contain not less than 16% milk fat but less than 32% milk fat and may also contain pH adjusting agents and stabilizers.  It can be pasteurized or UHT pasteurized and homogenized.
• Whipping Cream: shall contain not less than 32% milk fat but less than 40%; may contain pH adjusting agents, stabilizers, skim milk powder, glucose solids, calcium sulphate, xanthan gum and microcrystalline cellulose in regulated amounts.  Whipping cream is pasteurized but not usually homogenized unless UHT pasteurized.
• Another cream product found in the retail market is light cream which typically contains 5-6% fat in relation to the fat content of half-and-half cream (nutritional information must be on label when making a “light” claim).  Light cream is pasteurized or UHT pasteurized and homogenized.

Various Uses

Cream is a very versatile product and can be used straight from the package or as an ingredient in many food products.  One of the most common uses of cream (such as half-and-half cream) is adding it to coffee, tea, hot chocolate and other beverages where a richer flavour and texture and a characteristic colour are desired.  Table cream and whipping cream are often used as toppings to fresh fruit, desserts and cereals.

Cream can be found as an ingredient in a wide variety of products. Some common uses of creams are:

• Soups and sauces–fresh, dry-mix and canned 
• Sour cream – pasteurized cream (typically 18% milk fat) that is cultured with lactic acid bacteria or acidified with suitable acidifiers
• Casseroles and other creamy main meals
• Sweet syrups – caramels, fudges and fruit syrups 
• Ice Cream – cream is a key component in ice cream, providing the source of milk fat and functionality
• Cream fillings – whipping cream is typically used in decadent cream fillings for desserts 
• Cheesecakes
• Confectionary products – such as fondant centers and truffles 
• Bakery products – fresh and dried bakery mixes
• Alcoholic cream liqueurs and beverages
• Piping cream – whipping cream is often piped onto cakes and desserts 
• Other dairy products such as cheeses and yogurts – added to standardize fat content          

Functional Properties

Cream and other milk fat products (such as butter) are very different than fat from other animal and vegetable sources due to the presence of an aqueous phase, proteins and phospholipids.  Milk fat exists in the form of globules dispersed in an aqueous phase of milk.  Surrounding the fat globules is a membrane made up of varying proportions of protein, phospholipids and glycerides. The phospholipids in the membrane are of primary importance and account for much of the emulsifying properties of the fat globule membrane. The absorption of casein, proteins which are within the aqueous phase of cream, onto the milk fat globule surface when the globule membrane is disrupted (e.g. as a result of shear or homogenization), allows for production of variations in viscosity which can impart different functionality in food products. Caseins promote interaction with other molecules such as calcium, creating a new structure within the cream and therefore changing the textural properties.

The principle functional attributes of cream are:

• Flavour: Creams unique natural flavour adds richness to many foods and enhances other flavours in food products.  Due the narrow melting range of the milk fat in cream, cream provides quick release of flavours and taste sensations.
  
  
• Texture: Primarily due to the milk fat present in cream and the fat-protein network created during homogenization, cream adds rich, smooth viscosity and mouthfeel to many food products such as soups and sauces.
  
  
• Fat Soluble Ingredient Carrier: The milk fat in cream acts as a carrier of fat soluble vitamins and aids in the even distribution of other fat soluble ingredients.
  
  
• Emulsification: Creams natural proteins act as emulsifiers and aid in emulsification, aeration, foaming and overrun to give products such as whipped cream and ice cream a smooth and stable texture.
  
  
• Browning: Cream contributes to the browning of cooked foods through the Maillard browning reaction of the proteins and lactose found in cream. The Maillard reaction will also contribute to brown flavours in cooked food products containing cream.
  
  
• Whitening Colour: Cream adds a whitening effect in products such as coffee.  The colouring power of cream depends on the suspension of particles within the cream. Large particles in cream such as fat globules and casein reflect and scatter light creating a whitening effect.