Author

Erik N. Oberg

Date of Award

4-2013

Degree Type

Report

Degree Name

Master of Science (MS)

Department

Nutrition, Dietetics, and Food Sciences

First Advisor

Donald J. McMahon

Abstract

We examined the ability of polysaccharides to function as fat mimetics in low-fat (LF) mozzarella string cheese to improve functionality by acting like fat globules to separate protein fibers during cheese extrusion. Low-fat mozzarella cheese curd made from 273 kg of 0.7% fat milk was salted at a rate of 10 g/kg then divided into 3.6-kg batches that were hand-stretched in 5% brine at 80° C and formed into a homogeneous mass. The hot cheese was hand mixed with a hot 80° polysaccharide slurry, placed into a small piston-driven extruder and then forced through a 16-mm die to form the string cheese. Extruded string cheese was cut manually into approximately 15-cm lengths.

From preliminary trials using starches (waxy corn, waxy rice, and instant tapioca starch), xanthan and guar gums, and polydextrose, we determined that LF string cheese made using xanthan gum most closely resembled commercial string cheese. LF cheese was then made using a 10% xanthan gum slurry added at 0.25%, 0.5%, 1.0%, 1.5%, and 2.0% (wt/wt) levels. Cheeses were analyzed for fat, salt, pH, and moisture. After 2 wk of 4° C storage, the cheese was analyzed for extent of stringiness by pulling apart the cheese longitudinally, visually observing and photographing the size, length and appearance of individual strings of cheese. Hardness was determined using a Warner-Bratzler shear test. A consumer liking test was conducted after 2 and 8 wk storage time at 6° C.

At 2-wk storage, using a hedonic scale (1 to 9) for overall liking, the LF string cheese with 1% added xanthan slurry (score = 6.8) was liked more (PWhen considered on a JAR scale, most of the panelists scored the LF cheese with added xanthan gum (1%) as having the right texture, while only some did so for the retail cheese. The LF control cheese with no added gum was considered too firm. Using a visual comparison, adding the xanthan gum slurry produced greater fiber formation with the longest and most complete string separation. After 8 wk storage, the LF cheeses had softened extensively with fracture stress for LF cheese decreasing from 12 to 20 kg at 2 wk to 1.5 to 3 kg at 8 wk. Extent of stringiness also decreased during storage.

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