Overview:
This text delves into the realm of human nutrition, examining the chemical composition of various foods and their impact on our bodies. It begins by breaking down the basic components of food: water, dry matter, ash, and organic matter. The book then categorizes organic compounds into nitrogenous and non-nitrogenous groups, exploring each in detail. It highlights the importance of understanding the chemical makeup of foods, as this knowledge can inform our dietary choices for optimal health and well-being.
The latter part of the text dives into the practical application of this knowledge. It explores the impact of cooking on food composition, examining how heat, moisture, and ferments alter various nutrients. The book also delves into the role of bacteria in food preparation, both beneficial and detrimental. It further examines the value of a balanced diet, discussing dietary standards and the importance of considering both cost and nutritive value when making food choices.
Key Findings:
- Understanding the chemical composition of food is essential for informed dietary choices.
- Cooking can alter food composition, but not always its nutritive value.
- Bacteria play a significant role in both beneficial and harmful ways in food preparation.
- A balanced diet is crucial for maintaining health and maximizing the body’s ability to function properly.
- Dietary standards are valuable but tentative and should be tailored to individual needs.
- Food cost is not always an accurate indicator of nutritive value.
Learning:
- Nutrients: This text will educate the reader on the key nutrients found in food, including carbohydrates, fats, proteins, vitamins, and minerals. It will emphasize the role each nutrient plays in our bodies.
- Digestion: The reader will learn about the process of digestion, including the roles of various enzymes and the influence of factors like cooking methods and food combinations.
- Food Value: The text will explore the concept of food value, differentiating between nutritional content and overall dietary benefit. The reader will understand how to evaluate foods based on their composition, digestibility, and physiological effects.
- Dietary Standards: The reader will gain insights into dietary standards and how these standards relate to various levels of physical activity. They will understand that these standards are tentative and should be adapted to individual needs and lifestyles.
- Food Choices: The text will empower the reader to make informed food choices based on a comprehensive understanding of both cost and nutritional value.
Historical Context:
The book was written in 1914, a time when scientific understanding of nutrition was rapidly evolving. This context is reflected in the text’s emphasis on chemical analysis and its focus on basic dietary principles. While some of the information may be outdated, the core concepts of food composition and their relationship to health remain relevant today.
Facts:
- Water is essential for life. Water is a component of all plant and animal tissues and is crucial for the distribution of nutrients and the process of digestion.
- Ash (mineral matter) is crucial for plant growth. Essential elements like potassium, calcium, magnesium, iron, phosphorus, and sulfur are taken from the soil by plants.
- Animal bodies derive minerals from vegetable sources. Animals obtain essential mineral elements either directly or indirectly from the plants they consume.
- Cellulose is the basis of plant cell structure. It is present in various forms, some resistant to digestion, but often beneficial mechanically for promoting digestive function.
- Starch is the first carbohydrate produced in plant cells. It is widely distributed in plants, primarily in seeds, roots, and tubers.
- Cooking breaks down starch masses for easier digestion. Heat causes partial disintegration of starch granules, making them more readily accessible to digestive enzymes.
- Sugars are widely distributed in nature. They are found in the juices of plants like sugar cane, sugar beets, and sugar maple.
- Pectin bodies, found in fruits and vegetables, are converted into carbohydrates during digestion. They contribute to the jelly-like texture of some foods.
- Fat is a concentrated non-nitrogenous nutrient. It is primarily found in plant seeds and yields more energy than carbohydrates when burned.
- Organic acids provide flavor and potentially aid digestion. They are found in fruits and vegetables and can stimulate the secretion of digestive fluids.
- Essential oils impart flavor to foods. They are volatile and present in small amounts but play a role in taste and promoting digestion.
- Protein is a tissue-building nutrient. It is essential for the growth and repair of muscle tissue, and it is found in larger amounts in animal foods.
- Crude protein includes all nitrogenous compounds. It is determined indirectly by measuring total nitrogen and multiplying by a factor (6.25).
- Albuminoids are protein-like substances found in connective tissue. They differ from true proteins in composition and can help conserve body protein.
- Amids are simpler nitrogenous compounds. They are formed during oxidation and digestion of proteins.
- Alkaloids are nitrogenous compounds with potential medicinal properties. They are present in small amounts in some plants and can cause physiological effects.
- Legumes are rich in protein. Peas, beans, lentils, and peanuts are valuable sources of protein for humans, serving as substitutes for meat.
- Nuts are high in fat and protein. They provide a concentrated source of energy and can be an important part of a balanced diet.
- Milk is a complete food. It provides all essential nutrients and is crucial for infant development.
- Milk is susceptible to bacterial contamination. Strict sanitation measures are essential for ensuring milk safety.
Statistics:
- Vegetables can contain up to 95% water.
- Potatoes contain 10 parts of non-nitrogenous compounds to every 1 part of nitrogenous compound.
- Sweet potatoes contain about 6% sugar.
- Carrots contain nearly the same amount of water as milk.
- Spinach contains 2.1% crude protein.
- Tomatoes contain about 4% sucrose.
- Fresh, soft, green, sweet corn is about 50% starch and 25% sugar.
- Cereal foods contain from 0.5 to 1.5% mineral matter, about one third of which is phosphoric anhydrid.
- Wheat contains 72 to 76% starch.
- The roller process for flour milling recovers about 75% of the wheat kernel as flour.
- Patent grades of flour rarely contain more than 0.55% ash.
- Bread loses about 2% of dry matter during baking.
- About 1% of carbon dioxid gas is generated and lost during bread making.
- Flour contains about 65% starch, and during bread making about 10% is changed to soluble forms.
- Bread contains about 6% of soluble carbohydrates.
- From 45 to 65% of the total nitrogen in flour is in the form of gliadin.
- A good flour should absorb from 60 to 65% of its weight in water.
- A good flour should show at least 30% moist gluten and from 10 to 12% dry gluten.
- Average milk contains 87% water and 13% dry matter.
- Average butter contains 86% fat.
Terms:
- Nutritive Ratio: The ratio of non-nitrogenous compounds to nitrogenous compounds in a food.
- Digestion Coefficient: The percentage of a nutrient that is digested and absorbed by the body.
- Calorie: A unit of heat energy.
- Nitrogen Equilibrium: A state where the body’s intake and outgo of nitrogen are balanced.
- Hard Water: Water that contains a high concentration of dissolved minerals, primarily calcium and magnesium.
- Alkaline Water: Water that contains a high concentration of alkaline salts, such as sodium chloride, sodium sulphate, or sodium carbonate.
- Ferment: A substance, typically an enzyme, that catalyzes a chemical reaction, particularly in biological systems.
- Enzyme: A biological catalyst that accelerates biochemical reactions.
- Ptyalin: An enzyme found in saliva that breaks down starch into simpler sugars.
- Pepsin: An enzyme produced in the stomach that helps digest proteins.
Examples:
- Potatoes and potato skins: While potatoes are a valuable food source, their skins are proportionally richer in protein, but the protein is in a less available form.
- Green apples: Green apples are high in pectin, which is less soluble and digestible. During ripening and cooking, pectin becomes more soluble and digestible.
- Souring of milk: Lactic acid bacteria act upon milk sugar, converting it into lactic acid, causing milk to sour.
- Malted barley: Malted barley contains a soluble enzyme called diastase that changes starch into soluble forms.
- Ripening of cheese: The ripening process of cheese is driven by enzymes, particularly those found in milk.
- Beef tea: Beef tea is made by extracting soluble compounds from beef, including some protein and minerals, but it is deficient in actual nutritive value.
- Canned peas: Copper sulphate is sometimes used to enhance the color of canned peas, but it can interfere with digestion and potentially be harmful.
- Cocoanut oil: Cocoanut oil is a very concentrated source of fat and is used in various forms, including cooking and medicinal applications.
- Prepared milks: Prepared milks are mechanical mixtures of sugar, fats, and proteins, often lacking in fat content.
- Hard-boiled eggs: Hard-boiled eggs may be slightly more digestible than soft-boiled eggs, but the protein in both forms is readily absorbed by the body.
Conclusion:
This 1914 text provides a valuable glimpse into the understanding of food and nutrition during a time of scientific advancement. While some of the specific recommendations and dietary advice may be outdated, the core principles of understanding food composition, the importance of a balanced diet, and the impact of cooking methods on food remain relevant today.
The text highlights the importance of incorporating a variety of foods into our diets to ensure we receive all necessary nutrients. It emphasizes the importance of choosing foods with high nutritional value, particularly protein, and considering both cost and digestibility when making food choices.
Ultimately, this text encourages a more informed approach to eating and promotes the use of scientific knowledge to make healthier and more balanced dietary decisions.