Science and Engineering of Chinese Liquor (Baijiu): Microbiology, Chemistry and Process Technology

Foreword 1
Foreword 2
Foreword 3
Foreword 4
Preface
Contents
About the Editor
Part I: A Brief Introduction to Chinese Liquor
	1: History and Technology of Chinese Liquor
		1.1 The Origin of Alcoholic Beverages
		1.2 The Origin of Mijiu
		1.3 The Origin and Development of Shaojiu
			1.3.1 The Term Shaojiu Appeared Between the Qin and Han Dynasty
			1.3.2 The Record of Modern Daqu-Like Substance in the Northern Wei Dynasty
			1.3.3 Shaojiu in the Tang Dynasty
			1.3.4 Shaojiu and Doctors in Song Dynasty
			1.3.5 Distillers for Shaojiu in the Jin Dynasty
			1.3.6 Production Technology Records of Shaojiu in the Thirteenth to Fourteenth Century
			1.3.7 Shaojiu Made by Using Solid-State Fermentation Technology in the Ming Dynasty
			1.3.8 Shaojiu in the Qing Dynasty
		1.4 Technological Progress from 1910 to 1949
		1.5 Technological Progress After 1949
			1.5.1 Review the Traditional Process and ``Three Pilot Projects´´
			1.5.2 Liquor Quality-Improving Technology
			1.5.3 Liquor Yield-Improving Technology
			1.5.4 Innovation of Traditional Technology
			1.5.5 Analysis and Detection Technology of Process and Quality Control
			1.5.6 Application of Microbial and Enzymic Technology in Daqu and Liquor Fermentation
			1.5.7 Production Technology of Low-Alcohol Liquor
			1.5.8 Mechanization of Liquor Production Processes
				1.5.8.1 Mechanization of qu-Making
				1.5.8.2 Distillation System Reform
				1.5.8.3 Aging and Accelerated Aging
			1.5.9 Establishment of the Theory on Aroma or Flavor Types
			1.5.10 Establishment of a More Perfect Quality and Safety System
			1.5.11 Metabolic Regulation of Baijiu-Making Microbes Based on Flavor-Oriented Technology
		References
	2: Classification of Chinese Baijiu
		2.1 Introduction
		2.2 Starters Used for Baijiu Production
			2.2.1 Daqu
			2.2.2 Xiaoqu
			2.2.3 Fuqu
		2.3 Types of Chinese Baijiu
			2.3.1 Classification Based on Fermentation Methods
			2.3.2 Classification Based on Starters Used
			2.3.3 Classification Based on Aroma Styles
				2.3.3.1 Strong-Aroma Baijiu
				2.3.3.2 Light-Aroma Type Baijiu
				2.3.3.3 Sauce-Aroma Baijiu
				2.3.3.4 Rice-Aroma Baijiu
				2.3.3.5 Other Aroma Styles of Baijiu
		2.4 Manufacturing
			2.4.1 Strong-Aroma Baijiu Production
			2.4.2 Light-Aroma Baijiu Production
			2.4.3 Sauce-Aroma Baijiu Production
			2.4.4 Rice-Aroma Baijiu Production
		References
Part II: Solid-State Fermentation Technology and Principle of Chinese Liquor Processing
	3: Baijiu-Making Equipment
		3.1 Traditional Baijiu-Making Equipment
			3.1.1 Grain Storage
			3.1.2 Crushing Equipment
			3.1.3 Qu-Making Processes
				3.1.3.1 Qu-Making Molds
				3.1.3.2 Qu-Making Workshops
			3.1.4 Brewing Processes
				3.1.4.1 Fermentation Pits (Fermentation Containers)
					Mud Pits
					Pottery Jars
					Stone Pits
				3.1.4.2 Pit Unloading and Batching Systems
				3.1.4.3 Cooling Machines
			3.1.5 Distilling Processes
				3.1.5.1 Distillers
				3.1.5.2 Loading of the Steamer
				3.1.5.3 Liquor Receiving System
			3.1.6 Storage and Aging System
				3.1.6.1 Pottery Jar Storage
				3.1.6.2 Stainless Steel Tank Storage
				3.1.6.3 Bloodshot-Paper-Pasted Container Storage
				3.1.6.4 Pool Storage
			3.1.7 Blending System
			3.1.8 Solid and Liquid Material Transporting System
		3.2 Problems with Traditional Baijiu-Making Equipment
			3.2.1 The Issue of Efficiency
			3.2.2 The Issue of Quality
			3.2.3 The Issue of Safety
			3.2.4 Modern Industrial Challenges Faced by Traditional Equipment
		3.3 Modern Baijiu-Making Equipment
			3.3.1 Grain Storage
			3.3.2 Material Crushing
			3.3.3 Qu-Making Machinery
				3.3.3.1 Hydraulic Briquetting Machines
				3.3.3.2 Pneumatic Briquetting Machines
				3.3.3.3 Mechanical Stamping Machines
			3.3.4 The Fermentation Process
				3.3.4.1 Monitoring of the Fermentation Process
				3.3.4.2 The Batching System
			3.3.5 The Distillation Process
				3.3.5.1 Automatic Steamer-Loading Robot
				3.3.5.2 Automatic Liquor Picking Robot
			3.3.6 Other Modern Equipment
				3.3.6.1 Turnable Straight-Wall Steamer
				3.3.6.2 Rice Husk Cooking System
				3.3.6.3 Automatic Temperature Control Cooling Machine
				3.3.6.4 Intelligent Liquor Dispensing System (Fig. 3.50)
				3.3.6.5 Blending System
				3.3.6.6 Material Conveying System
		3.4 Trends and Prospects of Future Development
		References
	4: Process Principles and Engineering of Solid-State Fermentation of Baijiu
		4.1 Introduction
		4.2 Traditional Processing of Baijiu
			4.2.1 Solid-State Fermentation of Qu Making
			4.2.2 Heap Fermentation
			4.2.3 Solid-State Fermentation During Alcoholic Fermentation
		4.3 Challenges in Solid-State Fermentation of Baijiu
		4.4 Processing Principles and Engineering of Baijiu
			4.4.1 The Essence of Solid-State Fermentation During Qu Making
			4.4.2 The Essence of Solid-State Fermentation During Pit Fermentation
			4.4.3 Prospects
		References
	5: Solid-State Distillation of Chinese Liquor (Baijiu)
		5.1 Introduction
		5.2 Brief History of Solid-State Distillation of Chinese Baijiu
			5.2.1 Origin of Solid-State Distillation of Chinese Baijiu
			5.2.2 Development of Solid-State Distillation of Chinese Baijiu
		5.3 Traditional Solid-State Distillation Production Process of Chinese Baijiu
			5.3.1 Distillation Preparation
			5.3.2 Steamer-Filling
			5.3.3 Distillation
		5.4 Problems and Prospects in Solid-State Distillation of Chinese Baijiu
		5.5 Distillation Principles and Engineering of Chinese Liquor
			5.5.1 The Essence of Ethanol Distillation
			5.5.2 The Essence of Solid-State Distillation
			5.5.3 Prospects
		References
Part III: Flavour Chemistry of Chinese Liquor
	6: History and Advance of Flavour Research of Baijiu
		6.1 Achievements of Flavour Research on Baijiu
			6.1.1 Aroma-Active Compounds in Baijiu
			6.1.2 Key Aroma Compounds in Baijiu
			6.1.3 Combinatorial Chemosensory Code of Baijiu
		6.2 Analytical Methods for Flavour Compounds in Chinese Baijiu
			6.2.1 Preseparation Techniques in Aroma Analysis
				6.2.1.1 Direct Injection (DI)
				6.2.1.2 Headspace Sampling
					Static Headspace Sampling (SHS)
					Dynamic Headspace Sampling (DHS)
					Solid Phase Microextraction (SPME)
					Stir Bar Sorptive Extraction (SBSE)
				6.2.1.3 Solvent Extraction
					Liquid-Liquid Extraction (LLE)
					Liquid-Liquid Microextraction (LLME)
					Solvent-Assisted Flavour Evaporation (SAFE)
					Solid Phase Extraction (SPE)
					Microwave-Assisted Extraction (MAE) and Ultrasound-Assisted Extraction (UAE) (Fig. 6.13)
			6.2.2 Sensory-Directed Flavour-Analysis Techniques Used in Baijiu Flavour Analysis
		References
	7: Sensory Properties of Baijiu
		7.1 Introduction
		7.2 Aroma and Taste of Chinese Baijiu
			7.2.1 Aroma Compounds in Baijiu
				7.2.1.1 Strong-Aroma Baijiu
					Quality-Based Volatile Compounds
					Aroma-Active Compounds in Strong-Aroma Baijiu Studied with GC-O Technology
					Selective Extraction and Fractionation for the Comprehensive Identification of Other Aroma-Active Compounds
				7.2.1.2 Light-Aroma Baijiu
				7.2.1.3 Sauce-Aroma Baijiu
				7.2.1.4 Chi-Aroma Baijiu
				7.2.1.5 Sesame-Aroma Baijiu
			7.2.2 Taste Research of Chinese Baijiu
		7.3 Odour Threshold and Odour Activity
			7.3.1 Aroma Compound Threshold in Baijiu
			7.3.2 Perceptual Interactions of Aroma Compounds in Chinese Baijiu
		7.4 Sensory Evaluations of Baijiu
			7.4.1 National Baijiu Evaluation Conference
			7.4.2 Sensory Evaluation of Baijiu
		7.5 Conclusion
		References
	8: Chemical Components of Chinese Baijiu
		8.1 Introduction
		8.2 Volatile Components
			8.2.1 Alcohol and Water
			8.2.2 Volatile Organic Compounds
		8.3 Non-Volatile Constituents
			8.3.1 Elemental (Metal) Composition
			8.3.2 Organic Acids
			8.3.3 Nitrogen-Containing Compounds
				8.3.3.1 Amino Acids
				8.3.3.2 Peptides
		8.4 Off-Flavours
		References
Part IV: Research Advances of Microorganisms Associated with Chinese Liquor Production
	9: Microbial Diversities During Chinese Liquor Fermentations
		9.1 Filamentous Fungi
			9.1.1 Microbial Diversity of Filamentous Fungi During Baijiu Fermentations
				9.1.1.1 Light-Aroma Baijiu
				9.1.1.2 Strong-Aroma Baijiu
				9.1.1.3 Sauce-Aroma Baijiu
				9.1.1.4 Other Baijiu Flavor Types
			9.1.2 Morphological Characteristics of Filamentous Fungi
			9.1.3 Functional Characteristics of Filamentous Fungi in Baijiu
			9.1.4 Physiological Characteristics and Genomic Information of Typical Filamentous Fungi
				9.1.4.1 Rhizopus chinensis
				9.1.4.2 Rhizopus oryzae
				9.1.4.3 Aspergillus oryzae
		9.2 Yeast
			9.2.1 Microbial Diversity of Yeasts During Baijiu Fermentations
				9.2.1.1 Sauce-Aroma Baijiu
				9.2.1.2 Strong-Aroma Baijiu
				9.2.1.3 Light-Aroma Baijiu
				9.2.1.4 Other-Aroma Baijiu
			9.2.2 Morphological Characteristics of Yeasts
			9.2.3 Functional Characteristics of Yeasts in Baijiu
			9.2.4 Physiological Characteristics and Genomic Information of Typical Yeasts
				9.2.4.1 Saccharomyces cerevisiae
				9.2.4.2 Saccharomycopsis fibuligera
				9.2.4.3 Pichia kudriavzevii
		9.3 Bacteria
			9.3.1 Microbial Diversity of Bacteria During Baijiu Fermentations
				9.3.1.1 Strong-Aroma Baijiu
				9.3.1.2 Light-Aroma Baijiu
				9.3.1.3 Sauce-Aroma Baijiu
			9.3.2 Morphological Characteristics of Bacteria
			9.3.3 Functional Characteristics of Bacteria in Baijiu
			9.3.4 Physicochemical Characteristics and Genomic Information of Typical Strains
		9.4 Actinomycetes
			9.4.1 Microbial Diversity of Actinomycetes During Baijiu Fermentations
				9.4.1.1 Strong-Aroma Baijiu
				9.4.1.2 Sauce-Aroma Baijiu
				9.4.1.3 Light-Aroma Baijiu
				9.4.1.4 Sesame-Aroma Baijiu
			9.4.2 Morphological Characteristics of Actinomycetes
			9.4.3 Functional Characteristics of Actinomycetes in Baijiu
				9.4.3.1 Enzymes Produced by Actinomycetes During Baijiu Fermentation
				9.4.3.2 Metabolites Produced by Actinomycetes During Baijiu Fermentation
				9.4.3.3 Bioregulatory Effects of Actinomycetes on Microbial Community Fermentation
			9.4.4 Physicochemical Characteristics and Genomic Information of Typical Strains
		9.5 Prospection
		References
	10: Composition and Succession of the Microbiota in Light-Aroma Baijiu Production
		10.1 Introduction
		10.2 Composition and Succession of the Microbiota in Light-Aroma Daqu
			10.2.1 Composition of the Microbiota in Light-Aroma Daqu
				10.2.1.1 Microbial Diversity Investigated by Culture-Dependent Approach
				10.2.1.2 Microbial Diversity Investigated by PCR-DGGE
				10.2.1.3 Microbial Diversity Investigated by HTS and Shotgun Metagenomics
			10.2.2 Microbial Succession During the Spontaneous Fermentation and Storage of Light-Aroma Daqu
				10.2.2.1 Effect of Temperature on Microbial Succession of Light-Aroma Daqu
				10.2.2.2 Effect of Environmental Factors on Microbial Dynamics During the Incubation of Light-Aroma Daqu
				10.2.2.3 Microbiota Dynamics During Storage of Light-Aroma Daqu
			10.2.3 Source of Microbial Communities in Light-Aroma Daqu
		10.3 Composition and Succession of the Microbiota During Material Pretreatment for Liquor Fermentation
			10.3.1 Composition and Succession of the Microbiota During Soaking and Cooling
			10.3.2 Role of Microbiota During Material Pretreatment
		10.4 Composition and Succession of the Microbiota During Fermentation
			10.4.1 Composition and Succession of the Microbiota in Different Periods of Light-Aroma Baijiu
				10.4.1.1 Dynamics of Physicochemical Characteristics and Volatile Flavours in Different Periods
				10.4.1.2 Composition and Succession of the Microbiota During Fermentation in Different Periods
				10.4.1.3 Correlation Between Microbiota and Flavours During Fermentation in Different Periods
			10.4.2 Composition and Succession of the Microbiota in Different Workshops
				10.4.2.1 Metabolic Profiles During Fermentation from Different Workshops
				10.4.2.2 Composition and Succession of the Microbiota During Fermentation from Different Workshops
				10.4.2.3 Correlation Between Microbiota and Flavours During Fermentation from Different Workshops
		10.5 Effect of Environmental Microbiota on Fermentation
			10.5.1 Composition of the Microbiota in Different Environments
			10.5.2 Source Tracking of Microbiota During Fermentation of Light-Aroma Baijiu
		10.6 Conclusion
		References
	11: Diversity and Succession of the Microbiota in Sauce-Aroma Baijiu
		11.1 Introduction
		11.2 Diversity and Succession of the Microbial Community of High-Temperature Daqu
			11.2.1 Microbial Community and Succession During High-Temperature Daqu Making Process
			11.2.2 Microbial Co-occurrence of High-Temperature Daqu
			11.2.3 Changes in Flavour Compounds of High-Temperature Daqu During Storage
		11.3 Diversity and Succession of the Microbiota During Fermentation
			11.3.1 Diversity and Succession of Prokaryotic Community
			11.3.2 Diversity and Succession Rule of Eukaryotic Community
			11.3.3 Determination of Core Functional Yeasts
		11.4 Traceability Analysis of Functional Microorganisms of Sauce-Aroma Baijiu
		11.5 Interaction Mechanism of Microorganisms in Sauce-Aroma Baijiu
			11.5.1 Influence of Pichia on Disruption of Microbiota and Ecological Regulation Mechanism
				11.5.1.1 Microbial Flora Characteristics
				11.5.1.2 Flavour Characteristics
				11.5.1.3 Antifungal Evaluation and Antibacterial Mechanism Analysis of Volatile Substances Produced by Pichia pastoris
				11.5.1.4 Effects of Pichia on Other Functional Microorganisms During Sauce-Aroma Baijiu Fermentation
			11.5.2 Yeast Flora Remodelling and Lactic Acid Tolerance Interaction Mechanism
				11.5.2.1 Effect of P. kudriavzevii C-16 on the Degradation of Lactic Acid by Yeast Flora
				11.5.2.2 Effects of Microbial Interaction on Transcription of Genes Related to Lactic Acid Degradation
				11.5.2.3 Effects of Microbial Interaction on Osmotic Maintenance Related Gene Transcription
		11.6 Fermentation Parameters and Metabolites During Fermentation of Sauce-Aroma Baijiu
			11.6.1 Analysis of Physical and Chemical Parameters
			11.6.2 Changing of the Ethanol and Acids During Fermentation
			11.6.3 Production of Volatile Components During Fermentation
		11.7 Conclusion
		References
	12: Composition, Succession and Key Species of Microbiota in Strong Aroma-Type Baijiu Production
		12.1 The Microbiota of the Starter for Strong-Aroma Baijiu Fermentation
		12.2 The Succession of Microbiota in Fermented Grains of Strong Aroma-Type Baijiu
		12.3 The Sources of Microorganisms in the Production of Strong-Aroma Baijiu
		12.4 The Microbial Structure of Pit Mud, an Essential Source Providing Anaerobes to Produce Flavour Compounds
			12.4.1 The Microbial Community Structure of Pit Mud with Diverse Ages
			12.4.2 The Correlation Between Microbiota and Physical- or Chemical-Characteristics of Pit Mud
			12.4.3 Functional Anaerobes in Pit Mud
		12.5 The Flavour Contribution of Pit Mud Anaerobes to Strong Aroma-Type Baijiu
		References
	13: Functional Microorganisms Associated with Baijiu Fermentation
		13.1 Microorganisms Associated with Raw Material Degradation
			13.1.1 Amylase-Producing Microorganisms
			13.1.2 Protease-Producing Microorganisms
		13.2 Microorganisms Associated with the Formation of Volatile Flavour Compounds
			13.2.1 Alcohols-Producing Microorganisms
				13.2.1.1 Diversity and Characteristics of Alcohol-Producing Microorganisms
				13.2.1.2 Metabolic Pathways of Alcohol-Producing Microorganisms
			13.2.2 Acid-Producing Microorganisms
				13.2.2.1 Diversity and Characteristics of Acid-Producing Microorganisms
				13.2.2.2 Metabolic Pathways of Acid-Producing Microorganisms
			13.2.3 Ester-Producing Microorganisms
				13.2.3.1 Diversity and Characteristics of Ester-Producing Microorganisms
				13.2.3.2 Metabolic Pathways of Ester-Producing Microorganisms
			13.2.4 Terpene-Producing Microorganisms
				13.2.4.1 Diversity and Characteristics of Terpene-Producing Microorganisms
				13.2.4.2 Metabolic Pathways of Terpene-Producing Microorganisms
			13.2.5 Pyrazine-Producing Microorganisms
				13.2.5.1 Diversity and Characteristics of Pyrazine-Producing Microorganisms
				13.2.5.2 Metabolic Pathways of Pyrazine-Producing Microorganisms
			13.2.6 Sulphur Compound-Producing Microorganisms
				13.2.6.1 Diversity and Characteristics of Sulphur Compound-Producing Microorganisms
				13.2.6.2 Metabolic Pathways of Sulphur Compound-Producing Microorganisms
			13.2.7 MicroorganismsProducing Other Functional Compounds
				13.2.7.1 Diversity and Characteristics of Microorganisms Producing Other Functional Compounds
				13.2.7.2 Metabolic Pathways of Microorganisms Producing Other Functional Compounds
		13.3 Microorganisms Associated with Other Functions
		References
	14: Microbial Interaction in Chinese Liquor Fermentation
		14.1 Concepts of Microbial Interaction
		14.2 Characteristics of Microbial Interaction in Chinese Liquor Fermentation
			14.2.1 Cooccurrence Network of the Microbial Community
			14.2.2 Interaction Between Yeasts and Filamentous Fungi
				14.2.2.1 Effect of Environmental Factors on Interaction Between Saccharomyces cerevisiae and Aspergillus oryzae
				14.2.2.2 Effect of Inoculation Ratio on Interaction Between Saccharomyces cerevisiae and Aspergillus oryzae
				14.2.2.3 Effect of Inoculation Ratio on Flavour Compounds Production in Coculture of Saccharomyces cerevisiae and Aspergillus ...
			14.2.3 Interaction Among Yeasts
				14.2.3.1 Interaction Between Saccharomyces cerevisiae and Wickerhamomyces anomalus
				14.2.3.2 Interaction Between Saccharomyces cerevisiae and Pichia kudriavzevii [14]
			14.2.4 Interaction Between Yeasts and Bacteria
				14.2.4.1 Interaction Between Saccharomyces cerevisiae and Bacillus licheniformis [15]
					Effect of Microbial Interaction on Cell Growth
					Effect of Bacillus licheniformis on Ethanol and Flavour Compounds Production by Saccharomyces cerevisiae
					Mechanism of Interaction between Saccharomyces cerevisiae and Bacillus licheniformis Using Metaproteomics
				14.2.4.2 Interaction Between Saccharomyces cerevisiae and Lactobacillus buchneri [17]
					Saccharomyces and Lactobacillus Are Related with Sulphur Metabolism
					Effect of Interaction on Sulphur Metabolism
		14.3 Effects of Microbial Interaction on Liquor Fermentation
			14.3.1 Effect of High-Order Microbial Interactions on Flavour Compound Production [11]
				14.3.1.1 Pairwise Interaction Between the Dominant Species
				14.3.1.2 Higher-Order Interactions Among the Dominant Species
				14.3.1.3 Effect of Microbial Interaction on Flavour Compound Production
			14.3.2 Effects of Interaction Between Intrinsic and Extrinsic Microbes on Flavour Compound Formation [12]
				14.3.2.1 Influence of Extrinsic Microbes on Microbial Growth in the Coculture
				14.3.2.2 Influence of Extrinsic Yeasts on Ethanol and Flavour Compound Production
			14.3.3 Construction of a Synthetic Microbiota Based on the Microbial Interactions
				14.3.3.1 Using the Multi-Module Division of Labour to Produce 3-(Methylthio)-1-Propanol
				14.3.3.2 Construction of Synthetic Microbiota to Produce 3-(Methylthio)-1-Propanol
		References
	15: Regulation of the Microbiota in Chinese Liquor Fermentation Process
		15.1 Regulation of Initial Microbiota in Baijiu Fermentation
			15.1.1 Sources of the Microbiota
				15.1.1.1 Daqu Fermentation (Starter)
				15.1.1.2 Stacking Fermentation
				15.1.1.3 Baijiu Fermentation
			15.1.2 Control of the Initial Microbiota
				15.1.2.1 Bioaugmentation of Microorganisms in Daqu Fermentation
				15.1.2.2 Bioaugmentation of Microorganisms in Baijiu Fermentation
		15.2 Environmental Regulation of Microbiota
			15.2.1 Regulation of Environmental Factors in Baijiu Fermentation at Large Scale
				15.2.1.1 Biogeographic Factors Regulating Microbiota in Baijiu Fermentation at Spatial Scale
				15.2.1.2 Climate Factors Regulating Microbiota in Baijiu Fermentation at Temporal Scale
					Strong-Aroma Baijiu
					Light-Aroma Baijiu
			15.2.2 Regulation of Physicochemical Factors in Baijiu Fermentation at Micro-Scale
				15.2.2.1 Starter Fermentation
					Daqu Fermentation
						High-Temperature Daqu for Making Sauce-Aroma Baijiu
						Medium-Temperature Daqu for Making Strong-Aroma Baijiu
						Low-Temperature Daqu for Making Light-Aroma Baijiu
					Xiaoqu Fermentation
				15.2.2.2 Stacking Fermentation
				15.2.2.3 Liquor Fermentation
			15.2.3 Spatial Distribution of Microbial Community in Baijiu Fermentation in Pit
			15.2.4 Regulation of Raw Materials on Microbial Community in Baijiu Fermentation
			15.2.5 Regulation of Processing Techniques on Microbial Community in Baijiu Fermentation
		15.3 Prospective
			15.3.1 Synthetic Microbiota for Contractable and Reproducible Baijiu Fermentation
			15.3.2 Regulation of Environmental Factors
		References
	16: Challenges and Perspectives (Strategies)
		16.1 From Microbiome to Ecological Fermentation Technology and Microbiome Engineering
			16.1.1 Ecological Fermentation Technology
			16.1.2 Microbiome Engineering
		16.2 From Flavour Chemistry to Flavour Perception
		16.3 From Traditional Processing to Modernized Processing
			16.3.1 Modernization of Daqu Fermentation
			16.3.2 Modernization of Alcoholic Fermentation
		References