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Document Type

Thesis - University Access Only

Award Date

2005

Degree Name

Master of Science (MS)

Department / School

Agricultural and Biosystems Engineering

Abstract

Four treatments of Cheddar cheese with two levels (high and low) of calcium (Ca) and phosphorus (P), and two levels (high and low) of residual lactose were manufactured. Each treatment was subsequently split prior to the salting step of cheese manufacturing process and salted at two levels (high and low) for a total of eight treatments. The eight treatments included: High Ca and P, High lactose, high salt-to-moisture (S/M) ratio (HHH); High Ca and P, High lactose, Low S/M (HHL); High Ca and P, Low lactose, High S/M (HLH); High Ca and P, Low lactose, Low SIM (HLL); Low Ca and P, High lactose, High SIM (LHH); Low Ca and P, High lactose, Low SIM (LHL); Low Ca and P, Low lactose, High SIM (LLH); and Low Ca and P, Low lacto, Low SIM (LLL). After two months of ripening each treatment of cheddar cheese was used to manufacture process cheese using a twin-screw Blentech process cheese cooker. All of the process cheese food formulations were balanced for moisture, fat, and salt. The cheeses were then evaluated for chemical (moisture, fat, salt, pH, calcium, phosphorous, and lactose), functional (melt area, softening time-temperature, flow rate, extent of flow and TPA hardness), rheological (dynamic rheology), and linear viscoelasic characteristics. The results revealed a significant (P<0.05) decrease in melt area and softening rate and an increase in softening temperature and hardness in the high Ca and P treatments (HLL, HLH, HHL, and HHH) as compared to the low Ca and P treatments (LHH, LHL, LLH, and LLL). In dynamic rheological spectra G’ and G” values decreased during heating and cooling respectively. High Ca and P content and high salt-to-moisture ratio (HHH and HLH) process cheese had significantly high elastic (G’) and viscous (G”) moduli than other cheeses (HHL, HLL, LHH, LHL, LLH and LLL) throughout the heating and cooling process. Process cheese with high Ca and P content, high lactose and high S/M content had higher transition temperature (where G’=G”) than low CA and P content, low lactose, and low S/M content process cheeses. Process cheeses with low Ca and P content (LLL, LHH and LHL) and low S/M content (LLL, LHL, HLL) exhibited more viscous characteristics than high Ca and P content (HHL, HLH, and HHH) and high S/M content (HLH, LLH, and HHH) process cheeses during heating. Frequency sweep test was carried out at a constant stress of 750 Pa, and the data were best fitted into power-law model. Significant difference (P<0.05) was observed in low frequency storage and loss moduli (“a” and “c” respectively) between the Ca and P content (high/low) and salt content (high and low) in process cheeses. No significant differences were observed (P<0.05) for “a” and “c” values with residual lactose content (high and low) in the process cheese samples. Six-element Kelvin-Voigt model better predicted the creep compliance data for eight different process cheeses compared to four and five element models. It was observed that Ca and P content (high/low) and S/M ratio (high/low) content had significant effects on viscoelastic parameters such as J0 (instantaneous rigidity compliance), J1 and J2 (retarded compliances), r1 and r2 (retardation times), and 71v (Newtonian viscosity). Higher values were observed for J0, and retarded compliances (J1 and J2) by low Ca and P content (LHL, LLH) and low SIM ratio (HLL) content compared to high Ca and P content and high SIM (HHH) content process cheese. The functional and rheological characteristics of process cheese were affected more by level of Ca and P content (high/low) and salt-to-moisture (S/M) ratio content. In most cases residual lactose (high/low) showed no significant differences on functional, rheological, and linear viscoelastic characteristics between the cheeses. This study demonstrated that the characteristics of natural cheese (calcium and phosphorus content, lactose, and salt-to-moisture ratio) used in process cheese manufacturing have a significant impact on process cheese functional, rheological, and linear viscoelastic characteristics.

Library of Congress Subject Headings

Process cheese

Cheddar cheese

Calcium

Phosphorus

Lactose

Food -- Sodium content

Food -- Moisture

Format

application/pdf

Number of Pages

112

Publisher

South Dakota State University

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