Ice-Cream is the frozen milk product obtained by freezing a
pasteurized mix prepared from milk or other products derived from milk, or both, with or without addition of nutritive sweeteners and other permitted non-dairy ingredients. The said product may contain incorporated air and shall be frozen hard except in case of softy ice-cream where it can be frozen to a soft consistency. The composition of ice-cream must be as per defined regulation of FSSAI. Which is as under,m
Frozen Dessert or Frozen Confection means the product obtained by freezing a pasteurised mix prepared with edible vegetable oils or fats, having a melting point of not more than 37 Deg C or vegetable protein products, or both. It may also contain milk fat and other milk solids with the addition of nutritive sweeteners and other permitted non-dairy ingredients. The said product may contain incorporated air and may be frozen hard or frozen to a soft consistency.
Frozen ice-cream consists of four phases (Ice, Air, Fat and
Unfrozen continuous phase). The fat phase and air phase are assumed to be
constant after the ice-cream has been through the freezer. When the temperature of ice-cream is lowered during hardening, the water in the formulation freezes and
creating large ice crystals. Due to ice formation the unfrozen continuous phase
decreases and becomes more concentrated, causing its viscosity to increase and
slowing down the migration of lactose and other sugar molecules in the mix. The
combination of high lactose concentration and its reduced solubility due to lower
temperature results in supersaturated lactose solution that contains more sugar
molecules than if the system had been in thermodynamic equilibrium.
A standard ice-cream having 10% Fat,11% MSNF, 15 % Sucrose,2% glucose syrup and 0.5 % stabilizers and emulsifiers will have 200 Calorie/100 gm of ice-cream.
Scoopable ice-cream is a type of ice-cream that is scoopable at -18 Deg C and has a good creamy consistency, Slow melt down properties and good storage stability. This can be produced with best results by maintaining the desired FPDF(Freezing point depression factor)
Emulsifiers are surface active component located at the interface between oil and water making the two immiscible faces miscible. Frequently used emulsifiers are ice-cream are mono and di glycerides, Poly sorbates, PGMS, Phospholipids and proteins.
The function of hydrocolloids are to improve dryness and stiffness, reduce syneresis, Facilitate air incorporation and air cell distribution. Those most popular stabilizers are Locust bean Gum, Guar Gum, Xanthan gum, Carrageenan, Sodium Alginate, CMC and pectin.
The purpose of pasteurisation is to destroy pathogenic bacteria, Dissolve additives and ingredients before homogenisation, Increase the water binding ability of proteins and stabilizers. The common methods of pasteurisation are low temp long time(LTLT) 68 deg C FOR 30 Mins and high temp short time (HTST) 82 Deg C for 25 Sec.
Homogenization is a process to reduce the size of fat globules and disperse them uniformly. Two stage homogenisation is normally used in ice- cream. The homogenisation improves the whip ability, texture, storage stability and impart dryness. Homogenisation usually takes place between 65 deg C to 70 Deg C.
Aging is very important process of ice-cream manufacturing. Hydration of hydrocolloids and Protein, Fat crystallisation and displacement of casein micelles and whey protein from fat globule membrane takes place during aging.
Freezing the mix is one of the most important operations in
ice-cream manufacturing as the quality, palatability and yield of finished product is
dependent on freezing. The freezing of ice-cream is accomplished in two steps.
The frozen product is packed in different shapes, sizes, forms like cups, cones, moulded sticks, extruded products, paper packs, Tubs, parlour packs.
After freezing and packing the product need to harden
quickly at -35 deg C or colder to minimise the ice crystal size to make good texture
product.
Immediately after hardening the product goes to cold- rooms where it is store at -25 deg C or colder.
Shipping of ice-cream is done by maintaining the product temp -18 deg C or colder to maintain the quality of the product.
Mix stability is the resistance to separation of the milk proteins in colloidal suspension and the fat in emulsion. Instability results in separation of fat globules due to creaming, Protein particles as coagulated or participated material, a clear serum or whey from mix or melted ice-cream.
The density or specific gravity of ice-cream mix varies with the composition. Measurements of specific gravity made. The density can also be calculated by weighing a known volume of mix at a known temperature. The density of mix may vary from 1.05 to 1.12g/ml.
The titratable acidity of mixes varies with the % of the Milk solids not fat contained and may be calculated by multiplying the % of MSNF by the factor 0. 017.The acidity and PH of mix are related to the composition of mix. Increase in MSNF raises acidity and lowers the PH. The average acidity of ice-cream mix is 0.187% and PH is 6.3.
Viscosity is the resistance of a liquid to flow, is the internal friction that tends to resist the sliding of one part of the fluid over another. The standard unit of viscosity is the milli Pascal-second or centipoise, Cp.A certain level of viscosity is essential for proper whipping and retention of air, and for good body and texture in the ice-cream. The viscosity of mix is affected by composition, Processessing and handling of mix,temperature of mix.
The freezing point of ice-cream is depend on the concentration of the soluble constituents and varies with the composition. The freezing point of an average composition ice-cream mix is -2.5 Deg C.
