酶法液化制备梨和桃子的混浊汁

论文摘要

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,VC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。

论文目录

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