Introduction
Fat replacers are those substances that chemically resemble fat, proteins or carbohydrates and possess certain desirable physical or organoleptic properties of fat. Since there is an increase demand for low fat or no fat food products they are widely being used instead of fats and high fat consumption can lead to obesity, high blood cholesterol, diabetics and coronary heart disease.
Types of fat replacers
Fat substitute
These are fatty acid based products in which ester bonds are resistant to lipase catalysed hydrolysis. They are synthetic chemical entities prepared by either chemical synthesis or derived from conventional fats and oils by enzymatic modification.
Fat substitutes are categorised as
Designer lipids: These are triglycerides prepared by the chemical and enzymatic synthesis or random trans-esterification of short chain fatty acids or long chain fatty acids. Its commercial name is bene fat and has calorific value equal to 55% of the value of conventional fat.
Sucrose fatty acid polyester: It is called as olestra and mostly manufactured from saturated and unsaturated fatty acids of chain length of 12 carbon atoms. It can replace fat up to 100% and can be used for frying applications.
Sucrose fatty acid esters: The mono, di and trimesters of sucrose with fatty acids possess excellent emulsification and surfactant functionality. It has hydrophilic and lipophilic properties. They are useful in margarines, baked foods, frozen desserts, dairy products.
A caloric synthetic compounds: Dialkyl dihxadecylmalonates (DDM), Trialkoxycitrate (TAC), Trialkoxyglycerol ether (THE) are examples of this compounds. DDM may be used for replacement of oil in food formulations and for frying purpose.
Fat mimitics:These can imitate physical or organoleptic properties of fat and mostly protein and carbohydrate based. Calorific value ranges from 0-4kCal/g.
Fat mimitics which are carbohydrate based are
Gums: Gums are used as thickeners, stabilisers and gelling agents at 0.1-0.5%. Examples of this gums are xanthan gum, carrageenan, gum Arabic, pectins.
Starches: Modified starches are commonly used in food industry. It can perform well in high moisture foods such as mayonnaise, spreads, and salad dressings.
Cellulose: It is available as powdered cellulose, which is obtained by mechanical grinding,useful in reduced fat sauces, fried batter coatings, and increase the volume of baked goods. Micro crystalline cellulose is obtained by chemical depolymerisation and wet mechanical disintegration used in aqueous system for mouthfeel, and consistency. Sodium carboxymethyl cellulose are chemical derivatives of starch and are surface acting agents and can hydrate in water, form films in solutions and gel upon heating.
Maltodextrin: It is obtained from corn or potato starch by partial hydrolysis. They are not sweet and are used to improve viscosity, bind water, contribute mouthfeel for margarines, spreads etc.
Polydextrose: It is available in liquid or powder, acidic or neutralise forms. It is used in baked goods, baking mixes, chewing gums, confectionaries, salad dressing and so on.
Oatrim– This is prepared by partial enzymatic hydrolysis of starch containing portion of the hull or bran obtained from whole oat or corn flour. It is not suitable for frying applications but can withstand high temperature short time processing. It can improve the texture of low fat processed cheese in small concentrations.They are used in dairy products, confectioneries, frozen dessert, cereal baked goods, meat products.
Z-trim- This represents a zero calorie fat replacer and used for blending along with oatrim. It is an indigestible soluble fibre made from high cellulose portion of the hulls of the oats soybeans, peas. It contributes softness and moistness.
Protein based fat mimitics are
Whey protein concentrate- Products containing more than 50% concentration of the whey protein exhibit functional properties of fat replacers. The protein concentration, pH, temperature each play an important role in determining the nature of the aggregate which is small, soluble aggregate, or gel lattice structure.
Micro encapsulated proteins – Simplesse is manufactured from whey protein concentrate, eggs protein, milk. It is used in frozen desserts, yoghurt, cheese spreads, cream cheese. Use of simplesse in food products retains the biological value of proteins. K-Blazer, UltraBake, UltraFreeze are some other protein based fa tmimitics prepared from different protein sources.
Application of fat replacers in ice cream
In order to prepare low fat ice cream several fat replacers used are given below:
Inulin: Inulin which is a non-digestible polysaccharide can give an excellent mouthfeel properties. The sources of inulin are chicory root, and from some microorganisms as exo-polysaccharides.
Maltodextrin and polydextrose: Maltodextrin are produced by the partial hydrolysis of corn starch that have dextrose equivalent values less than 20. Maltodextrin and polydextrose are used in ice cream as they produce minimal negative effect on production, shelf life. Polydextrose acts as a bulking agent and resists gastrointestinal enzymes of human so that it provides only one calorie per gram.
Milk Proteins: Casein and whey protein are the two types of milk protein. Simplesse100is derived from the whey protein concentrate which is classified as protein based fat replacer can form gel like network. Concentrations of whey protein exceeding 50% can create products with functional properties that are helpful as fat replacer.
Soy proteins: It is vegetable protein source. 50% fat substituted ice cream with soy protein hydrolysates / xanthan gum had textural and sensory properties similar to that of control ice cream.
Plant gums: Plants such as agar, carrageenan, and guar gum are used as emulsifiers and stabilisers. They are macromolecules and mostly polysaccharide that can interact with water, develop texture and viscosity, gives lubricity and creaminess.
Cereal and fruit based dietary fibres: Cereals are source of lignin, hemicelluloses and cellulose, while fruits are sources of pectin, gums, mucilage. They help to increase waterholding capacity, emulsification, and gel formation. Dietary fibre addition can modify textural properties, avoid syneresis and increase in shelf life.
Starch: It is a polymer containing glucose monosaccharides. It is used as a thickener, stabiliser, gelling agent, water retention agent.
(Gagan Dip is M Tech (Food Science and Technology), IIFPT, Thanjavur, Tamil Nadu; and Sangma is M Tech (Dairy Technology),
NDRI, Bangalore. They can be reached at gagan.deep.399922@gmail.com)