Outline

  • Abstract
  • Keywords
  • Nomenclature
  • 1. Introduction
  • 2. Materials and Methods
  • 2.1. Production of Ketchup–processed Cheese Mixtures
  • 2.2. Chemical Analysis
  • 2.3. Descriptive Sensory Analysis
  • 2.4. Rheological Measurements
  • 2.4.1. Steady Shear Properties
  • 2.4.2. Dynamic Mechanic Analysis
  • 3. Results and Discussion
  • 3.1. Ph, Proximate Composition and Color Values
  • 3.2. Sensory Analysis Results
  • 3.3. Steady Shear Properties
  • 3.3.1. Effect of Temperature on Apparent Viscosity (η50)
  • 3.3.2. Effect of Pc Concentration on Apparent Viscosity (η50)
  • 3.3.3. Effect of Pc Concentration on Activation Energy (ea)
  • 3.3.4. Combined Effect of Temperature and Concentration on Apparent Viscosity (η50)
  • 3.4. Dynamic Shear Properties
  • 3.4.1. Stress Sweep Test
  • 3.4.2. Frequency Sweep Test (dynamic Viscoelastic Properties)
  • 3.4.3. Applicability of Cox–merz Rule
  • 4. Conclusions
  • References

رئوس مطالب

  • چکیده
  • کلیدواژه ها
  • 1.مقدمه
  • 2. مواد و روش
  • 2.1. تولید ترکیبات پنیر فرآوری شده سس گوجه فرنگی
  • 2.2. تحلیل شیمیایی
  • 2.3. تحلیل توصیفی حسی
  • 2.4. اندازه گیری های رئولوژیکی
  • 2.4.1. خواص برش ثابت
  • 2.4.2. تحلیل مکانیکی پویا
  • 3. نتایج و بحث
  • 3.1. PH، مقادیر ترکیبی ترکیبات و رنگ
  • 3.2. نتایج تحلیل حسی
  • 3.3 ویژگی های برش ثابت
  • 3.3.1 اثر دما بر ویسکوزیته ظاهری
  • 3.3.2. اثر غلظت PC بر ویسکوزیته آشکار
  • 3.3.3. اثر غلظت PC بر انرژی فعال سازی
  • 3.3.4 اثر ترکیبی دما و غلظت بر ویسکوزیته ظاهری
  • 3.4. خواص برش پویا
  • 3.4.1. آزمون sweep تنش
  • 3.4.2 آزمون sweep فرکانس (خواص ویسکوالاستیکی پویا)
  • 3.4.3 کاربرد قانون Cox-Merz
  • 4. نتیجه گیری

Abstract

The steady and dynamic shear properties of ketchup–processed cheese (K–PC) mixtures were investigated at different temperatures (10–50 °C) and PC concentrations (0–30%). The K–PC mixtures showed a shear-thinning behavior with low magnitudes of yield stress. The consistency coefficient (K) and apparent viscosity (η50) decreased with increase in temperature and concentration. The mixtures followed the Arrhenius temperature relationship, indicating that the magnitudes of activation energies (Ea) were in the range of 8.83–17.16 kJ mol−1. Storage (G′), loss (G′′) and complex (G∗) modulus increased with increase in frequency while complex viscosity (η∗) decreased. The K–PC mixtures at concentrations of 0–15% exhibited weak gel-like behavior. Increase in the PC concentration resulted in a decrease in G∗, G′, G′′ and η∗ up to the 15% of PC concentration, showing a plateau value between 0% and 30% concentrations. Cox–Merz rule was not applicable to K–PC mixtures.

Keywords: - - - -

Conclusions

The ketchup-processed cheese (K-PC) mixtures at different concentrations (0-30%) exhibited a shear-thinning behavior with low yield stress values (σ0). The effect of temperature on apparent viscosity (η) of K-PC mixtures is clearly explained by the Arrhenius relationship with high correlations (R2). Mathematical models were developed for the estimation of η50 of K-PC mixtures as a function of PC concentration and temperature. Judging from the R2 values, an exponential model appears to be a better choice than a power-law model with respect to effect of the temperature and concentration ranges studied on the K-PC mixtures. On the other hand, the multiple regression analysis showed that the statistically fitted model of Eq. (7) could be proposed to analyze the combined effect of temperature and concentration on the η50 values of K-PC samples. Based on the frequency sweep data of storage (C) and loss (G”) moduli as a function of frequency, the K-PC mixtures at concentrations of 0-30% exhibited the rheological behavior similar to weak gel-like macromolecular dispersions with C much greater than G” within the whole range of frequency applied. The Cox-Merz rule was not applicable to the K-PC mixtures and the departure of K-PC mixtures from the rule was determined to be concentration-dependent.

In this study, the compositional properties of ketchups could be changed by the usage of processed cheese (PC) at particular combinations, which could give rise to alterations in their rheological and sensory properties. Such modifications would be of great economical importance to food industry. PC can be used to improve these properties when appropriate levels of this product are taken into consideration. Ketchup mixed with processed cheese (K–PC) is a newly developed product in this study and has not been produced yet in the food industry. There is no published data informing the rheological and sensory properties of this product. Therefore, information obtained in this study may be useful in practical industrial food product process monitoring and development.

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