Food colloids butter

The examples in Table 12-3 illustrate the diversity of colloidal suspensions. Colloidal suspensions are commonly found in nature, and humans have learned how to make useful suspensions. Some of these are foods such as butter, Ice cream, and whipped cream. Others are personal care items like shampoos, shaving creams, and hair sprays. 

Raw milk is a unique agricultural commodity. It contains emulsified globular lipids and colloidally dispersed proteins that may be easily modified, concentrated, or separated in relatively pure form from lactose and various salts that are in true solution. With these physical-chemical properties, an array of milk products and dairy-derived functional food ingredients has been developed and manufactured. Some, like cheese, butter, and certain fermented dairy foods, were developed in antiquity. Other dairy foods, like nonfat dry milk, ice cream, casein, and whey derivatives, are relatively recent products of science and technology. This chapter describes and explains the composition of traditional milk products, as well as that of some of the more recently developed or modified milk products designed to be competitive in the modern food industry. 

Lipids strongly influence, for good or evil, the flavour and texture of foods, especially high-fat products such as butter. The influence of various colloidal features of milk fat on the properties of milk and cream is considered in Chapter 4, while the crystallization of milk fat and how this may be controlled, modified and measured are reviewed in Chapter 5. Unfortunately, lipids are subject to chemical and enzymatic alterations which can cause flavour defects referred to as oxidative and hydrolytic rancidity, respectively. The storage stability of high-fat foods, especially mildly flavoured foods like milk, cream and butter, is strongly influenced by these changes which have been reviewed in Chapters 6 and 7. 

The use of activated carbon constitutes an integral part of the processing of many food products.1 It is adaptable to foodstuffs that are in a liquid state or can be dissolved in a suitable solvent. Activated carbon should not be applied to foods such as milk, butter, mayonnaise, in which a colloidal state must be preserved. When such a product—e.g., mayonnaise—is treated with carbon, the protective colloids are adsorbed and the emulsion is broken. 

Milk fat has been a natural part of the human diet for several millennia. The important attribute of milk fat as a food ingredient is its delicate, pleasing flavor. The flavor and mouth-feel of milk fat are far superior to those of any other edible fat. A large number of different flavor compounds occur in milk fat at their flavor thresholds. The palatability of dairy products is also influenced by the fat texture. The taste of milk results to a great extent from the emulsion-colloidal structure that of butter results from its crystalline structure. 

Colloidal solutions are also a type of emulsion, a mixture of two substances that would not normally mix. A substance that causes one substance to disperse in another is called an emulsifying agent or emulsifier. Soap is an emulsifying agent because it causes grease and water to form an emulsion. Some food additives are emulsifiers because they keep foods that would ordinarily separate into layers, such as peanut butter, in just one smooth emulsion. 

Processed foods are often colloidal systems such as suspensions, emulsions and foams [1]. Examples of food emulsions, which are the most commonly used products, are milk, cream, butter, ice cream, margarine, mayonnaise and salad dressings. Emulsions are also prepared as an intermediate step in many food processing items, e.g. powdered toppings, coffee whiteners and cake mixes. These systems are dried emulsions that are re-formed into the emulsion state by the consumer. 

Various natural pigments, including carotenoids, are widely used as additives to provide an attractive colour to manufactured foods (Nir et al., 1993 Antony and Shankaranarayana, 2001 Baker, 2001). Natural extracts have been used for this purpose for centuries, especially annatto, saffron, tomato, paprika and red palm oil. In the food industry, carotenoids are prepared in oily or aqueous mecha, including emulsions, colloidal suspensions, and complexes with proteins (Klaui, 1979). These preparations find widespread applications in margarine, butter, fmit juices and beverages, canned soups, dairy products, desserts and mixes, preserves and symps, sugar and flour confectionery, salad dressings, meat, pasta, and egg products. Carotenoids are also widely used as additives in animal feeds to impart the desired colour to animal tissues or to derived products, or to provide adequate vitamin supplies. 

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