basic food science
Introduction to Food Science
Definition of Food:
Food may be defined as "anything eaten or drunk that meets the need for energy, body building, regulation, and protection of the body to sustain life."
It includes any solid or liquid which, upon swallowing, can supply one or more of the following:
Materials from which the body can produce movement, heat, or other forms of energy.
Materials for growth, repair, regeneration, and reproduction.
Substances necessary to regulate processes of growth and maintenance.
Function of Food:
Food serves as fuel supplying energy to support daily activities and synthesize necessary materials within the body.
Food Science
Definition of Food Science:
Food Science is defined as the study of the basic chemical, physical, biochemical, and biophysical properties of foods and their constituents. It includes the study of changes that occur during handling, preservation, processing, storage, distribution, and preparation for consumption.
It is an applied science that merges concepts from various fields such as biochemistry, physics, microbiology, biotechnology, and nutrition.
Food Constituents
Definition:
Food constituents are biochemicals that combine to make a specific food, mainly derived from plants and animals, present in different proportions and arrangements in food systems. They impart characteristic taste, texture, structure, color, flavor, energy, and nutritional value.
Two foods may have a similar proportion of one or more constituents yet differ completely in physico-chemical and organoleptic properties. Understanding these constituents is essential for better comprehension of food's nature and composition.
Nutrients vs. Non-nutrients:
Nutrients: Components needed by the body to grow, reproduce, and maintain normal health, including water, protein, fats, carbohydrates, minerals, and vitamins.
Non-nutrients: Organic constituents of food having no nutritional function, which can be toxins or beneficial substances like fibers or compounds that improve palatability or have pharmacological importance. Examples include colors, acids, phytates, tannins, and phenolics.
Alcohol is cited as a non-nutrient mechanism due to its adverse effects on the body, contrary to dietary nutrients.
Food and Nutrition
Food Definition:
Foods are essential substances for the growth and development of organisms.
Organisms like plants produce their own food through photosynthesis; animals obtain food from plants and other animals.
Nutrition:
The process of obtaining nutrients or food is referred to as nutrition. Nutrients are the organic or inorganic substances that support survival and maintain health.
Classification of Nutrients:
Macro Nutrients: Required by the body in large amounts.
Micro Nutrients: Needed in minute or very small amounts (e.g., minerals and vitamins), primarily aiding in regulatory functions of the body.
Components of Food
A) Carbohydrates
Composition and Function:
Chemically made of carbon, hydrogen, and oxygen; primary source of energy for all living beings and the cheapest energy source.
Types include:
Starch
Sugars
Cellulose
Common Sources of Carbohydrates:
Starch:
Found in cereals (wheat, rice, maize), millets (bajra, jowar, barley), roots, and tubers (sweet potato, tapioca, potato).
Sugar:
Obtained from sugarcane, beetroot, fruits (banana, mango, sapota), milk, honey, etc.
Cellulose:
A fibrous substance not digestible by humans, serves as roughage aiding bowel movement.
Daily Requirement:
A normal person requires about 400-500 grams of carbohydrates daily to meet energy needs, with growing children, lactating mothers, and those with high physical exertion requiring more.
Functions of Carbohydrates:
Promotes growth of beneficial intestinal bacteria for calcium absorption.
Excess carbohydrates are converted to glycogen for energy storage.
Glucose and galactose are primary energy sources for the central nervous system.
B) Fats
Composition and Function:
Composed mainly of carbon, hydrogen, and oxygen, with a higher ratio of carbon and hydrogen.
Richest source of energy, yielding approximately 9.0 kcal of energy per gram upon oxidation.
Sources of Fats:
Obtained from ghee, butter, oils, meat, cheese, and cream.
Functions of Fats:
Serve as an energy source.
Comprise cell and tissue components.
Aid in absorption of fat-soluble vitamins (A, D, E, K).
Assist in synthesizing vitamin D and steroid hormones.
Act as insulators against cold and external shocks.
C) Proteins
Composition:
Complex organic molecules made of carbon, hydrogen, oxygen, nitrogen, sometimes sulfur, and phosphorus; composed of amino acids.
Amino acids:
Essential Amino Acids: Not synthesized in the human body; must be obtained from food.
Non-Essential Amino Acids: Synthesized in the body.
Sources of Proteins:
Found in nuts, milk, fish, liver, eggs, cheese, etc.
Functions of Proteins:
Structural components of the body essential for building and maintaining tissues.
Enzymes vital for digestion are composed of proteins.
Many hormones are protein-based, regulating body functions.
Proteins assist in transportation (e.g., hemoglobin transports oxygen) and immunity.
D) Vitamins
Characteristics:
Essential chemical substances required by the body in trace amounts for metabolic functions and protection against diseases.
Synthesized only for Vitamin D, others must be sourced externally.
Major Vitamins and Functions:
Vitamin A (Thiamine):
Sources: Yeast, liver, milk, cheese, leafy vegetables, meat, whole grain cereals.
Functions: Carbohydrate metabolism, appetite enhancement, heart, nerve, and muscle functioning.
Vitamin B2 (Riboflavin):
Sources: Milk, liver, eggs, peas, whole grains, leafy vegetables.
Functions: Carbohydrate and protein metabolism; skin health.
Vitamin B3 (Niacin):
Sources: Fish, eggs, meat, legumes, whole grains, peanuts, tomatoes, potatoes.
Functions: Protein, fat, and carbohydrate metabolism; maintains skin health.
Vitamin B12 (Cyanocobalamin):
Sources: Liver, fish, cheese, milk, eggs, meat.
Functions: Blood formation, nervous tissue metabolism, nucleic acid synthesis.
Vitamin C (Ascorbic Acid):
Sources: Cabbage, tomatoes, lemon, oranges, mangoes, chilies, guava, pineapple.
Functions: Resistance to infections; dental and connective tissue health.
Vitamin D:
Sources: Milk, cheese, egg yolk, fish, fish oil, sunlight exposure.
Functions: Bone health, calcium absorption.
E) Minerals
Definition:
Micro-nutrients important for the proper functioning and growth of the body, aiding proteins in performing normal functions.
Classification:
Major Elements: Calcium, phosphorus, potassium, sodium, chlorine, iron.
Minor Elements: Iodine, magnesium, cobalt.
Minerals Sources and Functions:
Iron:
Source: Green vegetables, grains, meat, eggs.
Function: Hemoglobin formation.
Calcium:
Source: Green vegetables, milk, eggs.
Function: Strong bones and teeth.
Phosphorous:
Source: Eggs, meat, fish, whole grains, milk.
Function: Strong bones and teeth.
Iodine:
Source: Sea food, iodized salt.
Function: Thyroid gland health.
Sodium:
Source: Table salt, vegetables, processed foods.
Function: Fluid balance, nerve conduction, muscle contraction.
Potassium:
Source: Milk, meat, vegetables, fruits.
Function: Fluid balance, nerve conduction, muscle contraction.
Magnesium:
Source: Vegetables, legumes, nuts, seeds.
Function: Muscle contraction and protein functioning in minute amounts.
F) Roughage
Definition:
Fiber present in food items like fruits and vegetables; it is not considered food but is essential in the diet.
Functions of Roughage:
Facilitates bowel movements and cleans digestive tracts.
Prevents constipation by retaining water in the body.
Maintains blood sugar and cholesterol levels.
G) Water
Importance:
Comprises about 75% of an infant's body and 70% of an adult's body.
Functions of Water:
Essential for digestion and transport of food materials.
Excretes waste and regulates body temperature.
Acts as a solvent in various biochemical reactions within the body.
Sources of Water:
Acquired from drinking fluids, fruit juices, milk, tea, coffee, and eating vegetables and fruits.
Balanced Diet
Definition:
A balanced diet contains essential nutrients in suitable proportions to provide the necessary energy and maintain health.
Qualities of a Balanced Diet:
Meets the nutrient requirements of the body.
Consists of various food items.
Provides adequate energy levels.
Nutritional Needs
For Growing Children
Requirements:
Increase in proportion to body weight.
Extra protein for tissue growth.
More calcium and phosphorus for bone and muscle cell formation.
Vitamin A for healthy eyesight and Vitamin C for general health.
Vitamin D for healthy bones.
During Pregnancy and Lactation
Requirements:
Pregnant women have heightened needs to support the developing embryo:
Extra protein for tissue growth.
More calcium and phosphorus for fetal bone formation.
Increased iron for the baby's blood supply.
Additional carbohydrates for energy to support building processes related to the embryo.
Food Spoilage
Definition:
Food spoilage refers to a change in quality, rendering food less suitable for human consumption, characterized by alterations in taste, smell, appearance, or texture.
Microbiological Spoilage:
It is an important mechanism contributing to food spoilage, affecting the food's desirability and safety for consumption. Changes may be detected through sensory evaluation (smell, taste, touch, vision).
Causes of Spoilage:
Physical and chemical changes lead to undesirable signals such as odors, flavors, colors, or textures and incur costly losses to the food industry.
Factors influencing spoilage include the composition of the food product and the microbial populations present.
Types of Spoilage
I. Autolytic Enzymatic Spoilage
Occurs post-mortem due to enzymatic breakdown of cellular membranes, affecting product quality.
II. Lipid Oxidation
Involves reactions between oxygen and fat molecules leading to rancidity.
III. Microbial Spoilage
Involves the growth of spoilage microbes, their metabolism of food components, and changes resulting from the death of microbes.
Microbial Growth in Food
Bacterial Growth:
Bacteria reproduce via binary fission, leading to four growth phases:
Lag Phase: Bacteria adapt to the environment with slow growth. Influenced by temperature, pH, and nutrient availability.
Log Phase: Rapid exponential growth occurs under favorable conditions. Doubling time generally ranges from 10-30 minutes.
Stationary Phase: Equilibrium between growth and death rates due to limited nutrients and excess waste.
Death Phase: More cells die than are born, often induced by hostile conditions such as low nutrient availability.
Factors Affecting Microbial Growth
Environmental Factors: Recognized by the acronym FATOM:
Food Composition: Availability of suitable nutrients is vital for bacterial growth.
Acidity (pH): Most microbes thrive in neutral to slightly acidic pH (7.0-4.6). Bacteria typically do not grow below pH 4.6.
Temperature: Each microbe has optimal growth temperatures; danger zone ranges from 41°F to 140°F.
Time: Sufficient time is required for adaptation and growth phases, significantly affecting bacterial population levels.
Oxygen: Some microbes require oxygen (aerobes), while others do not (anaerobes); levels of oxygen can determine microbial activity.
Moisture: Water activity (aw) availability is crucial, with bacteria needing higher levels than molds or yeasts.
Conclusion
Summary:
The study of food science encapsulates the composition, function, and spoilage of various food types, emphasizing the importance of nutrients, microbial growth dynamics, and the complexities of maintaining food safety and quality in a variety of contexts.Implications:
Understanding food constituents, their interactions, and spoilage mechanisms can help inform food processing practices and nutrition policies, contributing to improved health outcomes and food safety standards.