Lecture_17___cream_processing

Lecture_17___cream_processing - Cream Processing Carmen I...

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1 Cream Processing Carmen I. Moraru Cornell University Cream products - Cream = a oil-in-water emulsion with a fat content of 35-40%, obtained by centrifugal separation of fat from milk. - Cream = raw material for the manufacturing of: - Whipped/whipping cream : cream with 35 – 40 % fat content - Half / coffee cream : cream with 10 – 18% fat content - Sour cream (fermented dairy product) - Butter
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2 - Whipped cream is a foam, with a structure very similar to ice cream. - Structure formation: during whipping of heavy cream , the agitation and the incorporated air bubbles cause fat globules to partially coalesce and adsorb at the surface of the air bubbles. - Water, lactose and proteins are trapped in the spaces around the fat- stabilized air bubbles. Air bubble Whey protein membrane Casein micelles Partially coalesced fat globules Whipped cream Partial coalescence = irreversible agglomeration of fat globules in a shear field. Fat globules are held together by a combination of: - fat crystals : the crystals at the surface of the droplets cause the colliding globules to stick together - liquid fat (released from the fat globules as a result of mechanical action), which fills the space between globules and acts as a "cement". Whipped cream structure - SEM evidence of whipped cream structure:
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3 Whipped cream structure - SEM evidence of whipped cream structure: Photo : http://www.foodsci.uoguelph.ca A. Whipped cream overall structure: a = air bubbles; f = fat globules B. Internal structure of an air bubble, surrounded by a stabilizing layer of partially coalesced fat C. Details of the partially coalesced fat layer 30 μ m 5 μ m 3 μ m Whipping cream flow diagram Raw milk Centrifugal separation Standardization 35% fat optimum Cream Skim milk Thickening agent Pasteurization Cooling Packing Cold storage Whipping cream 5ºC 4ºC/24h 80-95ºC/10sec Ripening Acidification Homogenization pH=6.2-6.4 70ºC, 60-70bar (stage 1)/ 15-20bar (stage2)
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4 Whipping cream processing - The Scania method - Cream Heating medium Cold water Ice water 1 - Holding tank 2 - Product pump 3 - Pasteurizer 4 - Booster pump 5 - Holding tube 6 - Ripening tanks 7 - Product pump Photo : TetraPak Dairy Processing Handbook, 2003 To filling Factors that affect whipped cream properties – raw materials - Flavor - Fat associated off flavors (rancid, tallowy) in the original
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Lecture_17___cream_processing - Cream Processing Carmen I...

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