Production of ice cream includes the blending of mix ingredients, pasteurization, homogenization, aging of the mixture, freezing, packaging and hardening. Selection of ingredients is based on the desired formulation. Liquid ingredients are heated and add with powdered ingredients such as skim milk powder and sugar, followed by adding of stabilizer and emulsifier. Fat is the last item to add in. Normally, high shear mixer are used in blending because the premixing the powder ingredients is not necessary, agglomerate free mix, stable emulsion, rapid mixing times and maximize yield of raw material as thickening agents are fully hydrates and other ingredients are fully dispersed.
Pasteurization is to destroy the pathogenic bacteria, reduce spoilage organisms and hydration some of the components. It can be batch pasteurized or continuous pasteurization. Homogenization is done in two stage where formation of fat emulsion by breaking down milk fat globules to <1 ยต m. This is followed by the reducing cluster of the fat. Ageing is allowing time for fat to cool down and crystallize while the protein and polysaccharides can be fully hydrated. Ageing can improves the whipping qualities of mixture, body and texture of ice cream.
Freezing can be done using the barrel freezer. Hardening is done in hardening tunnels or contact-plate freezers. Factors affecting hardening time are freezer temperature, rapid circulation of air, container size, ice cream composition and package materials.
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