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Introduction to Microbiology

Applied Microbiology

Topic: Food MicrobiologyCourse Code: MICR1010Subject: Introduction to Microbiology and Molecular Biology

Learning Outcomes

Key Learning Goals

• Properties of Industrial Microorganisms: Understand and explain the essential properties that make certain microorganisms suitable for industrial applications, including their physiological and biochemical characteristics.

• Food Production Processes: Describe in detail the manufacturing processes for yogurt, cheese, and bread, emphasizing the role of microorganisms in fermentation and flavor development.

• Beverage Manufacturing: Discuss the nuances of beer making, including the different styles and their production techniques. Explore the complexities involved in both red and white wine making processes to appreciate the fermentation differences.

Characteristics of Industrial Microorganisms

Essential Characteristics

• Growth Capacity: Ability to thrive in large-scale cultures, which is crucial for cost-effective industrial production.

• Reproductive Capacity: Production of spores or reproductive cells for inoculation to maintain culture consistency.

• Rapid Growth and Product Formation: Quick multiplication allowing for efficient turnover in industrial settings, ensuring high productivity and responsiveness to production demands.

Properties of Useful Industrial Microorganisms

Key Properties

• Flavor and Aroma Production: Capability of synthesizing desirable flavors, textures, and aromas that enhance the sensory qualities of food products.

• Cost-Effective Growth: Ability to proliferate in inexpensive media, reducing overall production costs.

• Safety: Non-pathogenic nature, ensuring that products are safe for consumption.

• Genetic Manipulation: Amenability to genetic engineering, allowing for the enhancement of desired traits and production processes.

• High Product Yield: Capability to produce significant amounts of desired metabolites or compounds, maximizing output and efficiency.

Additional Properties

Advanced Features

• Non-Toxic End Products: Ensuring that the resulting fermentation products are safe and palatable.

• Harvesting Ease: Features that favor efficient harvesting post-production, reducing labor and resource costs.

• Minimal Growth Factor Requirements: Limited need for additional supplements, simplifying the growth medium and lowering production costs.

Fermented Foods and Microorganisms

Fermented Food Types and Primary Fermenters

Dairy Products:

• Types: Variety of cheeses, yogurt, and buttermilk.

• Microorganisms: Commonly used bacteria include Lactococcus, Lactobacillus, and Streptococcus thermophilus, each contributing unique flavors and textures through fermentation.

Alcoholic Beverages

Key Microorganisms

• Yeast Species: Saccharomyces sp, a pivotal organism utilized in the production of bread and various fermented beverages, responsible for fermentation and flavor development.

Further Fermented Foods

Key Fermented Products

• Meat Products: Utilization of Pediococcus and Lactobacillus for producing cured meats and sausages.

• Vegetables: Fermented vegetables involving Leuconostoc and Lactobacillus are key to producing products like sauerkraut and soy sauce, showcasing the diversity of fermentation processes.

Common Fermented Products

Notable Products

• Dairy: Includes Non-fat Kefir, Sour Cream, and Lowfat Buttermilk.

• Brands: Commonly known products include those offered by Lifeway, Daisy, and Schnucks, highlighting market diversity and consumer choices in fermented dairy products.

Microorganisms in Dairy

Dairy Product Microorganisms

• Yogurt: Cultured using strains such as Streptococcus sp. and Lactobacillus sp. for flavor and texture.

• Cheddar Cheese: Involves microorganisms like Streptococcus and Lactococcus.

• Diverse Dairy Products: Various strains contribute to the production of Cottage Cheese, Sour Cream, and Swiss Cheese, emphasizing the role of specific bacteria in each product's unique characteristics.

Yogurt Production Process

Steps to Make Yogurt

1. Pasteurization: Heat milk to eliminate spoilage bacteria and pathogens, ensuring safety.

2. Inoculation: Introduce Lactobacillus bulgaricus and Streptococcus thermophilus, key microbes for fermentation.

3. Incubation: Maintain at 40ºC for sufficient fermentation duration, allowing lactic acid production which generates yogurt's distinct flavor.

Steps of Yogurt Processing

1. Heat Treatment: Heat milk to between 80-95 °C to denature proteins and kill unwanted bacteria.

2. Cooling: Cool down to 40-45 °C, the optimal temperature for starter culture growth.

3. Fermentation Maintenance: Maintain the temperature for 3-6 hours to develop characteristic acidity and texture.

Yogurt Processing Continued

General Steps

1. Pasteurization Options: Utilize either 80°C for 30min or 95°C for 10min based on production preferences.

2. Cool Product: Once pasteurized, cool the milk to 40-45°C for the starter cultures to thrive.

3. pH Monitoring: Maintain the temperature until a pH of 4.5 is achieved, signifying successful fermentation.

Yogurt Finalization

Post-Fermentation Steps

1. Cooling: Quickly cool yogurt to 7°C to cease fermentation and enhance shelf life.

2. Customization: Add fruits, sweeteners, or flavors according to market demand.

3. Packaging: Properly package the product for distribution, emphasizing storage conditions to maintain product quality.

Cheese Production Overview

Cheese Basics

• Production: Involves curdling milk using rennin (rennet) and lactic acid cultures, resulting in the transformation of liquid milk into solid cheese curds.

Cheese Production Steps

Detailed Process

1. Fermentation: Convert lactose in milk to lactic acid, creating the initial acidity needed for curdling.

2. Curdling: Introduce rennet to form curds and whey.

3. Separation: Separate curds from whey, and flavor with salt as part of the aging process.

Factors Affecting Cheese Flavor

Production Influence

• Starter Cultures: Different bacteria contribute distinct flavors, promoting diversity in cheese profiles.

• Ripening Conditions: Variability in aging conditions such as temperature and humidity can significantly affect final taste.

• Secondary Microorganism Inclusion: Additional microbes can enhance or alter flavor during aging.

Cheese Ripening Process

Ripening Duration and Conditions

• Enzymatic Transformation: Involves proteolytic enzymes breaking down proteins, enhancing cheese texture and flavor.

• Microorganism Activity: Varied temperatures during ripening promote growth of specific microorganisms crucial for flavor development.

Different Types of Cheese

Classification

• Texture & Hardness: Cheeses can be classified based on texture and hardness into categories such as Soft, Semi-soft, Hard, and Very Hard, with each category exhibiting unique production and aging processes.

Bread Making Process

Ingredients and Fermentation

• Yeast Role: Saccharomyces cerevisiae ferments sugars found in dough, producing carbon dioxide (CO2) for leavening and ethanol for flavor development, crucial in achieving bread's texture and taste.

Additional Fermented Products

List of Common Foods

• Diverse Fermented Foods: Includes Cocoa, Olives, Pickles, and Sauerkraut, illustrating the broad spectrum of fermentation in food preservation and flavor enhancement.

Fermented Beverages Overview

Alcoholic Beverages Production

• Categories: Major categories include Beer, Wine, and Distilled beverages, each involving unique microbial processes and ingredient choices that influence flavor, aroma, and alcoholic content.

Wine Production Process

Key Steps

1. Grape Crushing: Begin with crushing grapes to release juice, the primary substrate for fermentation.

2. Fermentation: Yeast convert sugars into alcohol and carbon dioxide, crucial for flavor profiles.

3. Aging and Bottling: Post-fermentation aging enhances complexity, followed by bottling for distribution.

Brewing Process Steps

Beer Production Overview

1. Malting Grains: Soaking and germinating grains to convert starches into fermentable sugars.

2. Mashing: Mixing malted grains with hot water to extract sugars.

3. Fermentation and Bottling: Allowing yeast to ferment sugars, followed by bottling the finished product to capture carbonation and flavors.

Distillation in Alcohol Production

Distilled Beverages

• High Alcohol Content: Focus on producing spirits such as whiskey, vodka, and gin, each with specific distillation processes that amplify alcohol content and unique flavor characteristics.

Comparison of Alcohol Production Processes

Brewing vs. Distilling vs. Wine-making

• Method Differences: Specific methods vary according to the source material (grains for beer vs. grapes for wine), reflecting the distinct pathways of fermentation and production techniques.

Video Resources

Learning Tools

• Educational Aids: Links to instructional videos covering yogurt, cheese, beer, and wine-making processes to supplement theoretical learning with practical visual aids.