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酶法液化制备梨和桃子的混浊汁

作　者: Guy-Yackoisset-Dedemogane
导　师: 王璋
学　校: 江南大学
专　业: 食品科学
关键词: 梨和桃子 PPO热稳定性 褐变 酶解液化 果汁稳定性和储藏
分类号: TS255.44
类　型: 硕士论文
年　份: 2005年
下　载: 164次
引　用: 0次
阅　读: 论文下载
 

内容摘要


桃子是一种分布很广的果核类水果,由于它营养丰富,滋味可口和气味芳香而被人们所喜爱。中国是桃子的故乡,它排在苹果、梨之后,为第三大水果。此外,梨是一种梨果类水果,在落叶水果作物中排第二。 一般来说,桃子和梨都是新鲜消费的,但是由于采收后落后的手工包装处理以及较少的储存设施,大量的产品而被腐烂和损失。因此,开发桃子和梨的加工产品是一种降低新鲜水果损失可供选择的办法。 这篇论文的目的是优化生产桃子和梨混浊汁酶解工艺并研究它们的稳定性,主要结果如下。 梨和桃子一些物理化学性质被研究,新鲜梨和桃子的主要成分是糖类化合物。可溶固形物含量分别是9.75,12.25,pH分别为4.07,4.1。结果表明,梨和桃子中必需氨基酸分布相近。 梨和桃子中多酚氧化酶(PPO)热稳定性被研究。结果表明,梨中的PPO在pH7.0,25℃条件下稳定,而桃子中的PPO在pH6.8,7.0,30℃条件下稳定。桃子中的过氧化物酶(POD)热稳定性也被研究,但是,对于评价果浆是否热烫完全,POD不是合适的指标。 梨中的PPO在pH4.0-8.0都有活性,然而,桃子中的PPO活性范围在pH4.5-8.0。这两种水果的酶促褐变现象很明显,结果表明,热烫处理过程中,加入0.5%柠檬酸,100℃条件下保持7分钟,可有效降低酶促褐变。 关于梨和桃子果汁的处理工艺,通过响应面(RSM)分析和正交实验来优化梨和桃子果浆的酶解液化工艺。最佳加工条件如下:梨汁处理过程中,加入0.1%(v/w)的citozyrn cloud 100L,在40℃酶解1h,出汁率达到80%以上;桃汁处理过程中,加入0.05%(v/w)的pectinex ultra SPL,40℃酶解30min,出汁率达到78%。 桃汁和梨汁在加工过程中的褐变现象被研究。结果表明,当热烫处理不彻底时,酶促褐变是果汁颜色变化的主要原因。当果浆热烫充分时,非酶促褐变是果汁褐变的主要因素。 通过操纵一些影响因素,如pH,V_C浓度,储藏温度和巴氏杀菌程度,经处理后的果汁表现出较长的货架期和更加稳定的颜色,更好地保持营养成分。 梨汁和桃汁的最佳pH水平分别控制在3.8和4.1,可以更好地保持果汁性质和更长的货架期。 40℃的储藏温度对果汁质量和货架期有着负面的影响,然而,4℃和20℃储藏温度可以更好地保持果汁颜色的稳定性和质量,前者的效果强于后者。 实验中,梨和桃子的混浊汁的货架期大约为6个月。

全文目录


CHAPTER ONE  13-26
  1 INTRODUCTION AND LITERATURE REVIEW  13-26
    1.1 INTRODUCTION  13-14
    1.2 LITERATURE REVIEW  14-26
      1.2.1 PEACH: ORIGIN AND HISTORY  14-17
        1.2.1.1 ORIGIN OF PEACH  14-15
        1.2.1.2 HISTORY OF CULTIVATION  15
        1.2.1.3 CHINA'S PEACH SITUATION  15-16
        1.2.1.4 PRODUCTION  16
        1.2.1.5 PEACH FOLKLORE  16
        1.2.1.6 MEDICINAL PROPERTIES  16
        1.2.1.7 ALLERGENICITY OF PEACH  16-17
      1.2.2 PEAR: ORIGIN, VARIETALS AND SITUATION  17-19
        1.2.2.1 ORIGIN OF PEAR  17
        1.2.2.2 CHINA'S PEAR SITUATION  17-18
        1.2.2.3 CHINA'S PEAR INDUSTRY  18-19
        1.2.2.4 CLINICAL EXPERIENCE  19
      1.2.3 BROWNING OF PEAR AND PEACH  19-22
      1.2.4 THE POTENTIAL ROLE OF FOOD PHENOLICS  22-23
      1.2.5 CLOUDY JUICE PROCESSING  23-24
      1.2.6 CURRENT PROBLEMS IN PROCESSING OF CLOUDY JUICE  24-25
      1.2.7 OBJECTIVES OF THIS RESEARCH  25-26
CHAPTER TWO  26-34
  2 EVALUATION OF NUTRIENT COMPOSITION AND DETERMINATION OF BROWNING AT CUT SURFACE OF PEACH AND PEAR  26-34
    2.1 PART ONE: NUTRIENT COMPOSITION OF PEACH AND PEAR  26-31
      2.1.1 INTRODUCTION  26-27
      2.1.2 MATERIALS AND METHODS  27-28
        2.1.2.1 MATERIALS  27
        2.1.2.2 CHEMICAL METHODS OF ANALYSIS  27-28
          2.1.2.2.1 Protein content  27
          2.1.2.2.2 Fat content  27
          2.1.2.2.3 Titratable acidity  27
          2.1.2.2.4 Total soluble solids (TSS)  27-28
          2.1.2.2.5 Ash and Moisture  28
          2.1.2.2.6 Sugar contents  28
          2.1.2.2.7 Pectin analysis  28
          2.1.2.2.8 Vitamin C  28
          2.1.2.2.9 Determination of Ions  28
          2.1.2.2.10 Amino acids content  28
          2.1.2.2.11 pH  28
      2.1.3 RESULTS AND DISCUSSION  28-31
    2.2 PART TWO: DETERMINATION OF THE OCCURRENCE OF ENZYMATIC BROWNING AT THE CUT SURFACE OF PEARS AND PEACHES  31-34
      2.2.1 INTRODUCTION  31-32
      2.2.2 MATERIALS AND METHODS  32
        2.2.2.1 MATERIALS  32
        2.2.2.2 METHOD  32
      2.2.3 RESULTS AND DISCUSSION  32-34
CHAPTER THREE  34-46
  3 STUDY ON SOME PHYSICO-CHEMICAL PROPERTIES OF POLYPHENOL OXIDASE FROM PEAR AND PEACH  34-46
    3.1 Part one: SOME PHYSICO-CHEMICAL PROPERTIES OF POLYPHENOL OXIDASE FROM PEAR  34-39
      3.1.1 INTRODUCTION  34
      3.1.2 MATERIALS AND METHOD  34-36
        3.1.2.1 MATERIALS  34-35
        3.1.2.2 METHODS  35-36
          3.1.2.2.1 Extraction of PPO  35
          3.1.2.2.2 PPO activity assay  35
          3.1.2.2.3 Effect of pH on enzyme activity  35
          3.1.2.2.4 Heat inactivation of PPO  35
          3.1.2.2.5 Substrate specificity  35
          3.1.2.2.6 Effect of inhibitor  35-36
      3.1.3 RESULTS AND DISCUSSION  36-38
        3.1.3.1 Effect ofpH on PPO activity  36
        3.1.3.2 Heat inactivation of PPO  36-37
        3.1.3.3 Substrate specificity  37-38
        3.1.3.4 Inhibitors  38
      3.1.4 CONCLUSION  38-39
    3.2 Part two: SOME PHYSICO-CHEMICAL PROPERTIES OF POLYPHENOL OXIDASE FROM PEACH  39-46
      3.2.1 INTRODUCTION  39
      3.2.2 MATERIALS AND METHOD  39-41
        3.2.2.1 PLANT MATERIAL  39-40
        3.2.2.2 REAGENTS  40
        3.2.2.3 METHOD  40-41
          3.2.2.3.1 Total phenolic  40
          3.2.2.3.2 Extraction of PPO  40
          3.2.2.3.3 Assay of PPO activity  40
          3.2.2.3.4 Properties of PPO extract  40-41
          3.2.2.3.5 Optimum pH and temperature  41
          3.2.2.3.6 Substrate specificity  41
          3.2.2.3.7 Effect of inhibitors  41
      3.2.3 RESULTS AND DISCUSSION  41-45
        3.2.3.1 PPO activity and phenolic  41-42
        3.2.3.2 Effect of pH on PPO activity and stability  42-43
        3.2.3.3 Effect of heat inactivation on PPO activity  43-44
        3.2.3.4 Effect of substrate on PPO  44
        3.2.3.5 Effect of inhibitors  44-45
      3.2.4 CONCLUSION  45-46
CHAPTER FOUR  46-62
  4 BLANCHING TREATMENT AND ENZYMATIC HYDROLYSIS ON PEAR AND PEACH  46-62
    4.1 Part one: EFFECT OF BLANCHING TREATMENT AND ENZYMATIC HYDROLYSIS OF PEAR DURING THE PROCESSING OF JUICE  46-56
      4.1.1 MATERIALS METHODS  46-49
        4.1.1.1 MATERIALS  46
        4.1.1.2 METHODS  46-49
          4.1.1.2.1 BLANCHING TREATMENT  46
          4.1.1.2.2 PPO ACTIVITY ASSAY  46
          4.1.1.2.3 COLOR MEASUREMENT  46-47
          4.1.1.2.4 ENZYMATIC HYDROLYSIS OF PEAR  47-49
            4.1.1.2.4.1 ENZYME TREATMENT  47-48
            4.1.1.2.4.2 RESPONSE MEASUREMENT  48-49
      4.1.2 RESULTS AND DISCUSSION  49-56
        4.1.2.1 EFFECT OF BLANCHING ON PPO ACTIVITY AND JUICE COLOR  49-51
        4.1.2.2 RESPONSE MEASUREMENT  51-54
          4.1.2.2.1 Influence of independent factors on juice yield  51
          4.1.2.2.2 Influence of independent factor on juice pectin  51-52
          4.1.2.2.3 Influence of independent factor on total soluble solids of juice  52-53
          4.1.2.2.4 Influence of independent factor on juice color  53
          4.1.2.2.5 Influence of different factors on juice viscosity  53-54
        4.1.2.3 OPTIMIZATION OF PARAMETERS TO MAXIMIZE JUICE YIELD AND QUALITY  54-56
    4.2 Part 2: EFFECT OF BLANCHING TREATMENT AND ENZYMATIC HYDROLYSIS OF PEACH DURING THE PROCESSING OF JUICE  56-62
      4.2.1 MATERIALS  56
      4.2.2 METHODS  56-57
        4.2.2.1 BLANCHING TREATMENT  56
        4.2.2.2 PPO AND POD ACTIVITY  56
        4.2.2.3 COLOR DETERMINATION  56
        4.2.2.4 ENZYMATIC HYDROLYSIS OF PEACH  56-57
      4.2.3 RESULTS AND DISCUSSION  57-62
        4.2.3.1 EFFECT OF BLANCHING TIME ON ENZYMES ACTIVITIES  57-58
        4.2.3.2 INFLUENCE OF BLANCHING TIME ON PEACH JUICE COLOR  58-59
        4.2.3.3 EFFECT OF ENZYMATIC TREATMENT ON PEACH PUREE  59-62
          4.2.3.3.1 Influence of enzyme concentration on juice yield and turbidity  59
          4.2.3.3.2 Effect of enzymatic treatment time on juice yield and turbidity  59-60
          4.2.3.3.3 Effect of enzymatic treated temperature on juice yield and turbidity  60-62
CHAPTER FIVE  62-82
  5 PROCESSING TECHNOLOGY OF CLOUDY PEAR AND PEACH JUICES AND INFLUENCE OF VARIABLE CONDITIONS ON SELECTED QUALITIES PARAMETERS  62-82
    5.1 PART ONE: OPTIMIZATION OF JUICE PROCESSING PARAMETERS  62-69
      5.1.1 Introduction  62
      5.1.2 JUICE PROCESSING PARAMETERS  62-63
        5. 1.2.1 Blanching  62-63
        5.1.2.2 Optimum pulping ratio of sample to water  63
        5.1.2.3 Enzymatic hydrolysis  63
        5.1.2.4 Determination of optimum juice pH  63
      5.1.3 Analysis methods  63-64
        5.1.3.1 pH  63
        5.1.3.2 Viscosity  63
        5.1.3.3 Total solids  63
        5.1.3.4 Turbidity  63-64
        5.1.3.5 Color preservation of cloudy pear and peach juices during Sterilization  64
      5.1.4 RESULTS AND DISCUSSION  64-69
        5.1.4.1 Effect of pulping ratio of water to sample in juice parameter  64
        5.1.4.2 Effect ofpH on turbidity and viscosity of cloudy juice of pear and peach  64-66
        5.1.4.3 Color preservation of Cloudy Pear Juice during Sterilization  66-67
        5.1.4.4 Effect of sterilization on color, ascorbic acid and sugar content of juice  67-69
    5.2 PART TWO: PROCESSING TECHNOLOGY OF CLOUDY PEAR JUICE AND CLOUDY PEACH JUICE AND THEIR BEHAVIOR DURING THE STORAGE  69-82
      5.2.1 JUICE PROCESSING  69-70
      5.2.2 Methods:  70
        5.2.2.1 Protein  70
        5.2.2.2 Moisture, ash and total solids  70
        5.2.2.3 Sugar content  70
        5.2.2.4 Mineral content  70
        5.2.2.5 Brix  70
        5.2.2.6 Amino acid  70
      5.2.3 EFFECT OF STORAGE CONDITIONS ON QUALITY PARAMETER OF CLOUDY PEAR AND CLOUDY PEACH JUICES  70-71
      5.2.4 SENSORY EVALUATION  71
      5.2.5 RESULTS AND DISCUSSION  71-82
        5.2.5.1 COMPOSITION OF CLOUDY JUICE OF PEAR AND PEACH  71-72
        5.2.5.2 AMINO ACIDS COMPOSITION OF CLOUDY PEAR JUICE  72-73
        5.2.5.3 EFFECT OF STORAGE CONDITIONS ON CERTAIN COMPONENTS OF CLOUDY PEAR JUICE AND CLOUDY PEACH JUICE  73-79
          5.2.5.3.1 ASCORBIC ACID, TOTAL PHENOLIC AND SUGARS EVOLUTION OF CLOUDY PEAR JUICE  73-74
          5.2.5.3.2 ASCORBIC ACID AND SUGARS EVOLUTION OF CLOUDY PEACH JUICE  74-75
          5.2.5.3.3 AMINO ACIDS EVOLUTION OF CLOUDY PEACH JUICE DURING STORAGE  75-76
          5.2.5.3.4 EFFECT OF DIFFERENT STORAGE CONDITIONS ON TURBIDITY OF CLOUDY PEAR JUICE AND CLOUDY PEACH JUICE  76
          5.2.5.3.5 EFFECT OF DIFFERENT STORAGE CONDITIONS ON VISCOSITY OF CLOUDY JUICE OF PEAR AND PEACH  76-77
          5.2.5.3.6 EFFECT OF DIFFERENT STORAGE CONDITIONS ON COLOR STABILITY OF CLOUDY JUICE OF PEAR AND PEACH  77-79
        5.2.5.4 SENSORY EVALUATION OF CLOUDY PEAR JUICE AND CLOUDY PEACH JUICE  79-80
        5.2.5.5 MICROBIOLOGICAL ANALYSIS  80-82
          5.2.5.5.1 SAMPLE PREPARATION  80-81
            5.2.5.5.1.1 DETERMINATION OF TOTAL PLATE COUNT (TPC)  80
            5.2.5.5.1.2 DETERMINATION OF YEAST AND MOLD  80-81
          5.2.5.5.2 RESULT OF MICROBIOLOGICAL ANALYSIS  81-82
GENERAL CONCLUSION AND RECOMMENDATION  82-84
  GENERAL CONCLUSION  82-83
  RECOMMENDATION  83-84
REFERENCES  84-92
PAPERS PUBLISHED  92

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