發(fā)布時間：2021-04-26 22:20

　　羊乳的凝乳能力相對較差,加工酸奶后會導(dǎo)致酸奶乳清析出,奶酪得率降低,給加工企業(yè)帶來不小的經(jīng)濟(jì)損失。目前,已采用多種方法改善羊乳的凝乳特性,但有關(guān)于超高壓處理改善凝乳的研究報道較少。在不同貯藏溫度條件下（25℃、4℃）,研究了不同超高壓（200-500 MPa）對原料羊乳理化性質(zhì)的影響。在25℃條件下貯藏的原料羊奶,與未處理的樣品相比,經(jīng)過超高壓處理后蛋白質(zhì)構(gòu)象發(fā)生了變化,蛋白質(zhì)沉降系數(shù)發(fā)生改變、pH值、可溶性鈣和磷含量逐漸降低,粘度顯著降低（P>0.05）,以及在儲存結(jié)束時酪蛋白的水合度降低。相反,在4℃條件下貯藏的原料羊奶與25℃下儲存的樣品相比,超高壓處理與未處理的樣品表現(xiàn)出不同的特性。這可能是由于鈣和磷酸鹽與酪蛋白的結(jié)合,從而導(dǎo)致電荷的屏蔽和膠束排斥力的減少。因此,為了改善羊奶的凝乳特性,本研究通過Box-Behnken設(shè)計,在不同壓力（300、400和500 MPa）、保持時間（20、40和60min）和溫度（20、40和60℃）下評估通過超高壓處理對凝乳酶誘導(dǎo)凝膠品質(zhì)的影響。隨著壓力水平的升高、時間的延長或溫度的降低,凝乳時間呈下降趨勢,而凝膠強度和凝乳速率卻得到了改善... 

【文章來源】：中國農(nóng)業(yè)科學(xué)院北京市

【文章頁數(shù)】：107 頁

【學(xué)位級別】：博士

【文章目錄】：
摘要
abstract
Chapter 1 Introduction
    1.1 Goat's milk composition and coagulation properties
        1.1.1 Goat's milk production in the world
        1.1.2 Goat's milk composition and nutritional benefits
        1.1.3 Coagulation properties of caprine milk
    1.2 High hydrostatic pressure（HHP）
        1.2.1 High pressure equipment
        1.2.2 Effects of HPP on milk constituents and some properties of milk
            1.2.2.1 Casein micelles
            1.2.2.2 Whey proteins
            1.2.2.3 Mineral balance in milk
            1.2.2.4 Appearance and p H of milk
            1.2.2.5 Rennet coagulation properties of milk
    1.3 The main problems of the study
    1.4 General objectives of the study
    1.5 The specific objectives
Chapter 2 Combined effects of high pressure treatment and storage temperature on the physicochemical properties of caprine milk
    2.1 Introduction
    2.2 Materials and methods
        2.2.1 Caprine milk samples
        2.2.2 High hydrostatic pressure treatment
        2.2.3 Determination of p H
        2.2.4 Determination of soluble calcium and phosphorus
        2.2.5 Determination of the hydration of ultracentrifuged pellet
        2.2.6 Nitrogen analysis
        2.2.7 Turbidity
        2.2.8 Determination of color parameters
        2.2.9 Viscosity
        2.2.10 Particle size distribution
        2.2.11 Statistical analysis
    2.3 Results and discussion
        2.3.1 pH
        2.3.2 Hydration
        2.3.3 Nitrogen compounds
        2.3.4 Calcium and phosphorus in the serum phase
        2.3.5 Viscosity
        2.3.6.Turbidity and Size distribution
        2.3.7 Color
    2.4 Conclusion
Chapter 3 Rheological and microstructural properties of rennet gel made from caprine milk treated by HHP
    3.1 Introduction
    3.2 Materials and methods
        3.2.1 Milk supply and treatment
        3.2.2 Experimental design
        3.2.3 p H measurement
        3.2.4 Calcium（Ca）and phosphorus（P）in the serum phase
        3.2.5 Gel Electrophoresis
        3.2.6 Rheological measurements
        3.2.7 Texture measurements
        3.2.8 Water holding capacity（WHC）
        3.2.9 Microstructure
        3.2.10 Statistical analysis
    3.3 Results and discussion
        3.3.1 HP-induced changes in the p H and soluble Ca and P concentrations of caprine milk
        3.3.2 Rheological properties of rennet-induced gels from caprine and bovine milk
        3.3.3 Surface plots for rheological properties of rennet-induced gels from HP-treated caprine milk
        3.3.4 WHC and GF of rennet-induced gels from caprine and bovine milk samples
        3.3.5 Microstructure of rennet-induced gels from caprine milk
    3.4 Conclusion
Chapter 4 Microfiltration retentates of caprine milk treated by high hydrostatic pressure:physicochemical,protein structure and rheological properties changes
    4.1 Introduction
    4.2 Materials and methods
        4.2.1 Materials
        4.2.2 Microfiltration retentate（MFR）preparation
        4.2.3 High hydrostatic pressure treatment
        4.2.4 Milk and MFR composition analysis
        4.2.5 pH measurement
        4.2.6 Mineral analyses
        4.2.7 Particle size and zeta potential
        4.2.8 Turbidity
        4.2.9 Fluorescence spectroscopy Measurements
        4.2.10 Determination of Fourier transform infrared（FTIR）spectroscopy
        4.2.11 Sodium dodecyl sulphate-Polyacrylamide gel electrophoresis（SDS-PAGE）
        4.2.12 Rheological measurements
        4.2.13 Statistical analysis
    4.3 Results and discussion
        4.3.1 Physicochemical changes in MFR samples treated with HP
        4.3.2 Changes in the secondary and tertiary structure of proteins
        4.3.3 Rheological properties of MFR caprine milk samples treated by HP
    4.4 Conclusion
Chapter 5 The functionality of micellar casein powders produced from microfiltration retentate caprine milk treated by high hydrostatic pressure prior to spray drying
    5.1 Introduction
    5.2 Materials and methods
        5.2.1 Materials
        5.2.2 Microfiltration retentate（MFR）preparation
        5.2.3 High hydrostatic pressure treatment
        5.2.4 MCC powder preparing by spray drying of HP-treated MFR
        5.2.5 MCC powder composition analysis
        5.2.6 Solubility
        5.2.7 Foaming capacity and stability
        5.2.8 Emulsion Stability
        5.2.9 Microstructure
        5.2.10 Statistical analysis
    5.3 Results and discussion
        5.3.1 Solubility
        5.3.2 Foamability
        5.3.3 Emulsifying property
        5.3.4 Microstructure
    5.4 Conclusion
Chapter 6 Overall conclusion and recommendation
    6.1 Overall conclusion
    6.2 Recommendations
    6.3 Perspective
References
Acknowledgement
Resume



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