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Thesis - University Access Only
Master of Science (MS)
Agricultural and Biosystems Engineering
Nine different kinds of Hispanic cheeses were purchased from Special Cheese Company Inc., WI. They were four different fresh cheeses: Queso Blanco (QB), Queso Blanco con Frutas (QBCF), Queso Para Freir (QPF), and Panela (QPL); three melting cheeses: Queso Quesadilla (QQ), Queso Jalapeno (QJ)and Asadero (AD); two hard cheeses: Anejo Enchilado (AE) and Cotija (CT). They were ripened for up to four months. For each first, second and fourth month of storage, cheeses were evaluated for texture profile characteristics (hardness, cohesiveness, springiness, chewiness, resilience) by using a Sintech 2/D universal testing machine (MTS systems. Corp., Eden Prairie, MN). Melt profile characteristics (softening temperature, softening time, melting temperature, melting time, flow rate, extent of flow) of these cheeses were evaluated. Rheologieal characteristics (elastic modulus, viscous modulus, and viscoelastic characteristics) of these cheeses were determined by using a parallel-plate geometry viscoanalyzer.
The results revealed significant differences (P<0.001) in some textural properties (hardness, cohesiveness, chewiness and resilience) among three of different types of Hispanic cheeses. Hard cheeses (AE, CT) indicated the highest values (41.0 ~ 67.5 N) on Hardness properties followed by fresh cheeses (QB, QBCF, QPF, and QPL) and melting cheeses (QQ, QJ, and AD) showed the least values (10.4~ 15.0N) on those properties. With increase in months of storage, a significant decrease (P<0.05) in hardness was observed for all nine different kinds of Hispanic cheeses.
There was a significant decrease (P<0.001) in softening temperature, softening time, melting time, flow rate and extent of flow of nine different cheeses with increase in month of storage. Fresh cheeses (QB, QBCF, QPL, and QPF) and hard cheeses (AE and CT) indicated significantly higher softening temperature (45.4-51.0 °C), softening time (178 - 206 sec), melting time (404 -501 sec) than those of the melting cheeses (QQ, QJ and AD). However, flow rate (31.0 - 49.0 pm/sec) and extent of flow (71.0-78.0 %) of melting cheeses showed significantly higher values than those of fresh and hard cheeses.
In dynamic rheology spectra, elastic modulus (G') and viscous modulus (G") decreased during heating and increased during cooling.AE from hard cheese had the highest elastic (G' of 9.94 x 104'Pa) and viscous (G" of 2.44 x 104'Pa) moduli during heating and cooling. Fresh cheeses (QB, QBCF, QPL, QPF) showed higher elastic (G' of 2.64-3.63 x 104'Pa) and viscous (G") (0.79 -1.12 x 104'Pa) moduli than those of Melting cheeses (QQ, QJ, AD). With increase in temperature and months of storage, elastic (G') and viscous (G") moduli of all the cheeses decreased significantly (P<0.05).
A frequency sweep test was carried out at a constant stress of 100 Pa and data were best fitted into power-law model. Significant difference (P<0.05) was observed in low frequency elastic modulus ("a" value) among nine different kinds of Hispanic cheeses and "a" values significantly decreased with increase in months of storage. No significant differences were observed (P>0.05) for low frequency viscous modulus ("c" value) among samples and months of storage.
Five-element Kelvin-Voigt model better predicted the creep compliance data for eight of different kinds of Hispanic cheeses compared to six-element model. It was observed that nine different cheeses showed significant difference (P<0.05) on J0 (instantaneous rigidity) and J1 and J2 (retarded compliances). Highest values of instant compliance (J0, 3.32 x 10'^ Pa-1) and retarded compliances (J1 and J2, 2.53 x 10-5 Pa-1 and 0.80 X10-5 Pa-1) were observed for fresh cheese (QB). With increase in storage period, significant differences in instant compliance (J0) and retarded compliances (J1 and J2) values were observed among three different types of Hispanic cheeses.
Library of Congress Subject Headings
Includes bibliographical references (62-69)
Number of Pages
South Dakota State University
Copyright © 2006 Hee Joon Park. All rights reserved
Park, Hee Joon, "Studies on Functional and Rheological Characteristics of Hispanic Cheeses" (2006). Electronic Theses and Dissertations. 634.