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ABSTRACT
Traditionally, Cheddar cheese is made by the milledcurd method. However, because of the mechanization of cheese making and time constraints, the stirredcurd method is more commonly used by many largescale commercial manufacturers. This study was undertaken to evaluate quality differences during ripening (at 2 and 8°C) of Cheddar cheese made by the milled-curd and stirred-curd methods, using 4 different commercial starters. Twenty-four vats (4 starters × 2 methods × 3 replicates) were made, with -625 kg of pasteurized (72°C × 16 s) whole milk in each vat. Fat, protein, and salt contents of the cheeses were not affected by the starter. Starter cell densities in cheese were not affected by the method of manufacture. Nonstarter lactic acid bacteria counts at 90, 180, and 270 d were influenced by the manufacturing method, with a higher trend in milled-curd cheeses. Proteolysis in cheese (percentage of water-soluble N) was influenced by the starter and manufacturing method (270 d). Sensory analysis by a trained descriptive panel (n = 8) revealed differences in cooked, whey, sulfur, brothy, milk fat, umami, and bitter attributes caused by the starter, whereas only brothy flavor was influenced by storage temperature. The method of manufacture influenced diacetyl, sour, and salty flavors.
Key words: stirred curd, milled curd, Cheddar cheese, proteolysis
INTRODUCTION
Cheddar cheese making involves 2 phases-the conversion of milk to curd in the first phase, which is generally accomplished in 24 h, and the transformation of the young "green" cheese into a mature cheese in the second phase. Traditionally, the milled-curd (MC) method is used for Cheddar cheese manufacture. The MC method involves the process of "cheddaring" (which involves turning and flipping loaves of warm curd at regular intervals for 1 to 2 h for the development of acid, leading to a fibrous, "chicken breast-like" structure), followed by milling, hooping, and pressing. In the stirred-curd (SC) method of manufacture, the curds are continuously stirred after whey drainage, hence eliminating the traditional cheddaring and milling process. The SC method is the method of choice in highly mechanized cheese plants because of its relatively short manufacturing time.
Acidification is one of the most important operations in the manufacture of Cheddar cheese. Starters are added to cheese milk to achieve a uniform and predictable...