Contemporary Food Science and Nutrition

Flashcards about food science and nutrition.

Understand

Spoilage patterns of food.

Identify

Conditions required for microbial growth.

Microorganism

A very tiny organism that cannot be seen by the naked eye, which may be a single-cell or multicellular organism.

Sources of Bacteria

Soil, water, air, dust, edible plants and plant products, animals and animal products, intestinal tract of man and animals, employee's hands and contaminated food utensils and equipment.

Bacterial Growth

Increase in number of organisms, accomplished by cell division.

Food Nutrients Needed by Microorganisms

Carbohydrates, fats, proteins, vitamins, minerals, and water.

Water Activity (aw)

The amount of moisture needed for bacterial growth.

Water Activity (aw) of food products

Fresh meat and fish (0.99), Bread (0.95), Cheddar cheese (0.85), Jams and jellies (0.8), Dried fruit, caramels, and honey (0.6), Cookies (0.3), Milk powder, instant coffee (0.2).

Aerobic Bacteria

Grow rapidly only in the presence of free oxygen.

Anaerobic Bacteria

Require the absence of oxygen.

Facultative Anaerobic Bacteria

Can grow in both aerobic and anaerobic conditions.

pH

Measurement of the degree of acidity or alkalinity, scale of 0 to 14, most bacteria of public health concern grow best at pH values between 4.6 to 7.5.

Psychrophilic Bacteria

Grow best at refrigeration temperatures.

Mesophilic Bacteria

Grow best at room temperature.

Thermophilic Bacteria

Grow best at temperatures above 49°C.

Food Danger Zone (Temperature Range)

Between 4°C and 60°C

Natural Inhibitors of Bacterial Growth

Benzoic acid (Cranberries), Lyzozyme (Egg), Cinnimic aldehyde (Cinnamon), Nisin (Streptococcus lactis bacteria), Sorbic acid (Berries species), Sulphur dioxide (Atmosphere, coal tar & all sulphur drugs), Acetic acid (vinegar, fermented grapes), Lactic acid (Sour milk), Propionic acid (fermented foods).

Food Spoilage

When an undesirable change in the color, flavor, odor, or texture has occurred or when foreign substances in food products make foods unfit for human consumption.

Factors Contributing to Food Spoilage

Poor sanitation, enzymatic or chemical reactions, improper temperature controls, microbial growth, and mechanical abuse.

Two Major Categories of Food Spoilage

Microbial and Non-microbial

Three Types of Microorganisms That Cause Microbial Food Spoilage

Bacteria, yeasts, and mold.

Bacteria

Round, rod, or spiral-shaped microorganisms that generally prefer low-acid foods (high pH).

Yeast

Oval-shaped, metabolize sugar producing alcohol and carbon dioxide gas (alcoholic fermentation), and associated with foods high in sugar and acid.

Mold

Grow in the form of filaments, aerobic, common among intermediate moisture foods, and produce many changes in food.

Enzymatic Spoilage

Naturally found in all plants and animals, made mostly from proteins, and cause undesirable changes in color, texture, and flavor.

Chemical Spoilage

Common as oxidation of food components (air reacts with the unsaturated fat in the food to cause oxidative rancidity) and cause unpleasant stale smell or taste.

Insects and Rodent Spoilage

An infestation by insects and rodents causes significant spoilage worldwide, particularly to grain crops and cause food losses, damage, and contamination.

Temperature Abuse Spoilage

Deteriorates the color, texture, and nutritional value.

Mechanical Abuse Spoilage

Refers either in the raw state or in the packaged state.

Three groups of foods classified by ease of spoilage

Stable or nonperishable foods, semi-perishable foods, and perishable foods.

Examples of Stable or Nonperishable Foods

Rice, sugar, flour, and dry beans.

Examples of Semi-Perishable Foods

Potatoes, onions, some varieties of apples, beets, dry fruit, and nutmeats.

Examples of Perishable Foods

Meat, fish, poultry, most fruits and vegetables, eggs, and milk.