Elements of Nutrition:
  1. Nutrition is, of course, of paramount interest to humans. However, our knowledge of this science is surprisingly new, due to tremendous advances in our understanding of chemistry, biology, and biochemistry during the past century.
  2. Even as we have learned more about the science of nutrition, we have also had lots of food fads, both in the U.S. and abroad. (Note the problems caused by polishing rice in the Far East.)
  3. Some of these fads contain a lot of pseudo-science, mystical fervor, and one-idea-ism congregates around nutrition, because promising new discoveries can become the focus of millennial hope.

In fact some "fad" foods are still very much with us:

  1. Salisbury steak
  2. Corn flakes
  3. Graham crackers
  4. malted milk

However, we tend to use them now because we actually grew to like them! And in the case of corn flakes, they probably were better than the sausage and eggs they replaced.

More recent fads: fiber, vitamin C, vitamin E, Zen macrobiotic diet.

In the Macrobiotic diet: The optimal diet is said to balance "yin" and "yang" foods. It is composed of whole grains (50 to 60% of each meal), vegetables (25 to 30% of each meal), whole beans or soybean-based products (5 to 10% of daily food), nuts and seeds (small amounts as snacks), miso soup, herbal teas, and small amounts of white meat or seafood once or twice weekly. Some macrobiotic diets contain adequate amounts of nutrients, but others do not.

 

Elements of Nutrition--Review of Food Chemicals:
  1. Carbohydrates: bread, breakfast cereals, potatoes, rice, pasta, fruits, vegetables, desserts, candies.
  2. Fats: Also a prime energy source. Twice as many calories per pound as carbohydrates.
  3. Proteins: Contain nitrogen as well as carbon, hydrogen, and oxygen. They are also extremely important, making up much of our muscles, organs, blood cells, skin, nails, hair, teeth, and bones.

Exactly how much protein we need is a matter of debate. Current estimates suggest 40 to 60 grams a day (equal to 2/3 to 1 lb. of meat). Note, though, we get protein from other places that just meat.

In terms of simple calories, carbohydrates are the body’s preferred energy source, from daily food intake. After that comes fat (as a repository for excess calories), then protein/muscle. However, by the time we get to muscle we are in the malnutrition zone!

 

Vitamins:

Word was originally short for "vital amines." These are essential for life. However, more is not necessarily better: in large amounts, some can be quite poisonous!

Fat-soluble vitamins are more stable, but easier to overdose on with supplements. Water soluble vitamins break down much more easily, and are also harder to overdose.

Fat-soluble:
  1. Vitamin A: fat soluble, essential for vision, skin, and membranes. Poisonous in large amounts, but not as its precursor beta carotene (the latter will only turn you orange if you eat too much).
  2. Vitamin D: fat soluble, essential for bones. Can be made in humans from cholesterol and sunlight. Too little will cause rickets and soft bones. Also comes from (fortified) milk.
  3. Vitamin E: fat soluble. Poorly understood, but seems to be used in hormone production, cancer prevention, and anti-oxidant (which preserves other chemicals in the body and may help slow aging).
  4. Vitamin K: fat soluble. Used in clotting. Synthesized in our body by bacteria in our large intestine. Rarely found in vitamin pills, and probably should not be given to pregnant women.

Water-soluble:
  1. Vitamin B: water soluble. Actually a group of 8 vitamins ("B complex"). Most are involved with metabolism/energy production, hormone production, and many other important processes.
  2. Vitamin C: water soluble. Essential to form collagen, which holds our cells together. Also helps hold teeth, bones, and blood vessels together. Lack of vitamin C eventually causes scurvy, where wounds fail to heal, gums (and eventually everything) bleed(s) and eventually teeth fall out.

There are many other things that are essential to good nutrition: water, minerals, fiber, etc. Note that minerals, like vitamins, are essential—but too much of one or more can be poisonous!

Nutrition is complicated, and new discoveries (or at least revisions!) are being made all the time. Be careful of food fads. Again, common sense is important: a varied and balanced diet will keep most problems away most of the time.

 

 

 

Milk:
  1. Comes from mammals. Like eggs, designed to sustain young early on.
  2. Human milk is easier to digest for humans—less protein, and the protein that is there curdles less in the stomach.
  3. Humans are unusual because they drink milk a long time after birth--at least most "white" humans. Many, perhaps most, races (Asian, African, Arabic) are slightly lactose intolerant, however. They lack lactase. They can eat some milk products, though, such as cheese and yogurt.

    4. Milk "parts":
  4. Milk contains 87% water, plus milk fat (~4%), milk sugar* (lactose-made of glucose and galactose), protein, vitamins, and minerals.
  5. The two proteins are casein and whey (curds and whey). These are determined by what happens when milk separates.
  6. Casein comes in micelle units. These tend to clump or clot or curdle for a variety of reasons: age, ions, heat.
  7. The fat comes in bigger fat droplets. These are blebbed off of cells (p. 10), and actually are enveloped by the cell membrane!

Milk Treatments:
  1. Pasteurization: Used to kill TB and other microorganisms. Heated to 144 degrees for 30 min or 160 for 15 sec. (A special form of pasteurization is UHT, or "ultra-high temperature" pasteurization. Here the milk is heated to 280 degrees F for 1 sec. This allows the milk to be stored in a sealed carton at room temperature for several months. Note that the heating process changes the flavor of the milk slightly.)
  2. Homogenization: prevents "creaming". Blasts fat droplets to be smaller to keep the milk from separating into milk and cream.
  3. Addition of vitamins A and D.

    4. Most milk regular (i.e., non-skim) milk goes through steps 1, 2, and 3 above. Other forms of milk may have the following additional steps added:

  4. Centrifuging to get rid of fat, thus producing "skim milk." More protein may be added to make the milk thicker.
  5. Lactobacillus may be added to reduce lactose ("acidophilus" milk), or lactase enzyme may be added directly. The purpose of this is to break down lactose so that lactose-intolerant people can drink the milk.
  6. Condensed milk—vacuum evaporated, may have caramel flavor from heat. It is normally sweetened to hide the cooked flavor.
  7. powdered milk—made from skim milk, to keep the fat from going rancid.
  8. If we concentrate the milkfat (instead of getting rid of it) we have cream:

 

  1. Churning cream violently and warming helps cause butter to form, by smashing the fat blobs together until they stick to each other. (Butter is about 80% milk fat!)
  2. (Margerine is a butter substitute. Originally it was made from animal fat, but now it normally comes from hydrogenated vegetable oils.)
  3. Malted milk: Malted milk powder is a combination of fresh whole milk and an extract of cooked mash of malted barley and flour. This product is then dried to form a free-flowing powder. Malted milk powder has a unique flavor and is used in a variety of baked products and drinks, such as ice cream "malts." (Originally malted milk was mixed with hot water to give a complete, sterile beverage suitable for consumption by infants and invalids.)

 

Fermented Dairy:
  1. Yogurt (milk) and Sour cream (cream): acid from lactic acid bacteria.
  2. Cultured buttermilk, too. (yuk!) by another bacterium
  3. Cheese: contains the fat and the casein protein. Starts like yogurt, but then rennet is added, an enzyme extracted from the calf stomach. (Rennin is the pure form).
  4. "Green" cheese is new, unfinished cheese that needs to be ripened.
  5. Cheese hardness has much to do with water content and protein: more water and less fat is softer. "Sharp" cheese is flavored in part by ammonia! (NH3)

 

Eggs:
  1. How egg is made: The yolk is produced by ovulation in a hen's ovary. The yolk then travels down the oviduct for about 25 hours. During the first part the egg white is added. Most of the is spent putting the shell on.
  2. The egg shell is made out of calcium carbonate (CaCO3) and protein.
  3. Eggs contain complete protein (13% of the RDA for an adult), iron, phosphorus, vitamins A, D, and K. An egg contains about 80 dietary calories of energy.
  4. Eggs age; they lose carbon dioxide (CO2) and become more acidic. The egg also becomes runnier and the yolk thinner.
  5. Good eggs SINK, bad ones FLOAT. Why? Gas and also water content.
  6. Eggs are graded by quality (AA, A, B) and by SIZE. (jumbo, extra large, large, medium, small, peewee)
  7. Like milk, eggs are complicated. Slight changes in their chemistry (heat, acidity, salt, etc.) cause them to clump or coagulate. Too much coagulation can cause them to be rubbery (not enough water) or to curdle. Acids and salts promote coagulation, water and sugar retard it.
  8. Different egg proteins denature (or cook) at different rates, which is why parts stay runny. The chalazae stay runny longest due to ovomucin.
  9. Hard boiled eggs: Fresh eggs are harder to peel. Overboiling causes discoloration of the yolk due to iron sulfide. (Rotten eggs smell because of hydrogen sulfide!)
  10. Egg substitutes have fewer calories, fat, and less cholesterol. Usually they are really egg whites and food coloring.

 

 

 

Meat

Raising domestic animals for meat appears to have been around as long as organized agriculture.

Generally, people eat meat when game is plentiful, or when there is a lot of agricultural surplus—it takes more grain to raise animals for meat than it does to simply eat the grain ourselves. Thus, meat consumption is often associated with wealth and/or conspicuous consumption. (I.e., Henry VIII)

Broadly speaking, meat simply refers to animal tissues. Some include eggs in this.

More commonly, "meat" means muscle tissue. We use the term "variety meat" or "organ meat" for things like liver or heart.

Problem: eating too much meat can cause heart problems, esp. from saturated fats.

Meat is over half water, and up to 45% fat (pork), though skinless chicken can be as low as 5%. Beef: 22%. Fish: 10%.

Much of the rest is protein, in the form of contractile fibers (50%). 30% is pigments and enzymes, while 20% is connective tissue.

Muscles are held in place by connective tissue, including elastin for tendons and collagen. Cooking collagen breaks it down into gelatin.

Fat is both around the tissue and inside it as marbling. These fats act as both energy storage and also insulation. When cooked, fat helps flavor and separate the meat. Fats can be saturated (beef) or unsaturated (fish, lamb). This level of saturation explains why fish and chicken is softer out of the refrigerator than beef. However, unsaturated fats go rancid faster.

Flavor

Tenderness

well-exercised

little exercise

older

younger (when cooked)

fat—carries flavor

fat—lubricates and separates fibers when cooked

 

 

 

 

 

Red Meat

White Meat

slow fibers

fast fibers

use fat

use glycogen ("animal starch")

must have oxygen

can go anaerobic

Store oxygen as myoglobin, which causes the dark color

produce lactic acid (and cramps!) when no oxygen is present

Myoglobin does more than store oxygen and make meat red. It can also tell us something about how fresh the meat is. Over time myoglobin breaks down, turning older meat brownish-gray. Myoglobin also tells us how done meat is when cooking—it is what changes from pink in red meat to brown in well-done meat. Finally, myoglobin is what what turns bright pink when meat is treated with nitrites in some forms of curing.

So what makes some fish SO white? They are almost all fast muscle (useful for chases or getaways). Fish with endurance (salmon) have more dark. Fish is flaky when cooked because the muscle fiber structures are short. Also, there is little connective tissue (about 3%), and what is there is easily turned into gelatin.

Slaughtering is an important part of meat preparation. Animals that are killed suddenly have meat that will produce lactic acid as it ages. This helps preserve the meat. Animals that are chased around for a while will have less lactic acid. This results in gummy, dark meat with a higher pH and poorer storage qualities ("Dark cutting"). (It is illegal to sell dark cut meat.)

Right after killing the meat it is bled, to reduce parasites and improve storage life. Meat then starts to age. Age is not a bad thing, however, at least for beef; the meat starts breaking down a bit on its own, making it more tender and easier to digest. However, fats also start oxidize, which can cause off/rancid flavors. Saturated fats (i.e. beef) are more resistant to this. Unsaturated foods (like fish) should be eaten fresh. (Fish also goes bad at colder temperatures then other meats.)

While we are on the topic of good food going bad:

Clostridium perfringens. It is a food intoxication caused by bacteria that produce a toxin (when large amounts are ingested) and spores. It is the toxin that makes people sick, not the bacteria, and the toxin can only be produced in the human body. Clostridium Perfringens is almost everywhere; the big problem is that the bacteria we capable of producing the heat resistant spores. Clostridium Perfringens is anaerobic. It grows readily on turkey, meat gravy, casseroles, and other meat-based foods. Cooking foods in a slow cooker increases the chance that food may have Clostridium Perfringens. The symptoms of Clostridium Perfringen-caused illness are: nausea, diarrhea, and stomach cramps. It very rarely kills anyone.

Clostridium botulinum is another food intoxication; it is a very strong toxin-the strongest toxin known to man. This toxin grows most often in home-canned foods, especially in those with low acid content. The spores, which thrive only in oxygen-free surroundings, manage to get into canned ham or vacuum-packed cold cuts. If these products are allowed to reach a temperature of 50 F or higher (room temperatures), the spores will germinate into active bacteria causing the deadly nerve toxins. The toxins can be destroyed by temperatures above 160 F, but, because they are generally precooked, the cold cuts may not be cooked when consumed.

Salmonella is the most common food infection. It is found in meat, fish, and poultry products. Salmonella bacteria are killed when heated. Quite often foods become cross-contaminated because knives and the cutting board are not cleaned after using them on contaminated food. This is especially true if the cook is working with poultry, fish, and red meats. Usually, the symptoms take a longer time to show up. Symptoms include: nausea, diarrhea, vomiting, and stomach cramps.

Trichinosis is caused by consuming food which contains a microscopic worm called a Trichinella spiralis. It is usually in the muscle tissue of animal products. It is killed if the meat is cooked well. Trichinosis causes nausea, diarrhea, fever, muscle pain, and tiredness. In bad cases, it can cause heart and brain damage and even death.

 

Other Food Hazards:

Minor hazards:

Plant foods (fruits and vegetables) spoil due to microbial action and by internal aging. Both are enhanced by bruising or other injury. Aging can be much quicker than is readily apparent to the eye: corn and peas can lose 40% of their sugar 6 hours after picking! Some vegetables also get tougher. Cooking can also reduce vitamin content through leaching (vit. B and C) and heat damage. Chopping and shredding can also reduce vitamin content (esp. C) through enzyme activity.

Greater Hazards:

Green potatoes and sprouts contain bitter, poisonous alkaloids. One must cut out the green parts! (Potatoes, like tomatoes and eggplants, are from the nightshade family of plants, so the green portions can be poisonous.) Some think that products from the nightshade plant family may increase arthritis symptoms.

Some seeds—apple, pear, peach, apricot, plum, almond, citrus—contain traces of cyanide. Eating a few seeds is not a problem for an adult, but a half cup or more could make one seriously ill or even be fatal! Lima and kidney beans also contain cyanogens (cyanide-producing chemicals) when raw, but these chemicals are destroyed by cooking.

Some spices are poisonous if eaten in large quantities. Ex.: nutmeg, comfrey.

Eating lots of cabbage or cauliflower can aggravate thyroid/goiter problems.

More hazards: Make sure plants are washed!!! Things you can get from under-washed plants: amoebic dysentery, topical pesticide residues

 

BREAD
  1. Bread as we commonly think of it depends on wheat. As we mentioned earlier, the wheat is milled to get rid of the bran and the germ. The flour is then usually bleached, then aged (often chemically) to improve its baking qualities.
  2. When the flour is moistened and mixed the proteins form glutin. This is what makes dough "doughy"--both plastic and elastic, and allows dough enough "give" to be inflated by the CO2 produced by the yeast. Kneeding builds up the glutin structure, and forms the pockets of air that the yeast will later inflate more fully.
  3. Generally speaking, only wheat has glutin that is strong enough to make raised baked goods; they tend to collapse if they rise. Thus flour made from other grains tends to produce heavy, dense baked goods. That's why we tend to use wheat flour for everything, instead of, say, corn or oats.§ §
  4. Of course, dough doesn’t just rise by itself. It has to have some sort of leavening agent. Normally we use yeast, which eats sugar in the dough (and often added malt (maltose) extract) and produces CO2 and ethyl alcohol. The CO2 production makes the bread rise; it also flavors the bread. (The alcohol cooks away.)
  5. Baking soda can also be used to make doughs and batters rise a bit, especially if they need to rise quickly. However, the batter needs to be acid for this to work. Sour milk or a little lemon juice or vinegar can do this.
  6. Baking powder can also be used. It contains both baking soda and a dry acid. Baking powders are often "double acting"—they bubble when initially added to the batter (much like Alka Seltzer). They also produce bubbles again latter when heated, to do more rising.
  7. The "staling" process occurs when water molecules from the air bind to the glutin in the bread. Staling can be partly reversed by heating. Staling happens most rapidly at refrigerator temperatures, and much more slowly when frozen, or even at room temperature. This is why bread seems to go stale so fast in the refrigerator, but toasting it helps make it taste better.

Food Additives

1.     Food additives received a lot of attention during the late 1960’s and early 1970’s. Part of this was due to a “back to nature” that grew up along side of hippies, environmental awareness, and other movements of that era. People tended to treat food additives as a new, generally bad, innovation. They also tended to romanticize the past a lot.

2.     People tended to idealize life on the farm in the past. More drastically, there was a sort of “return to Eden” mentality.

3.     Actually, food additives have been around for a very long time.

4.     Also, “additive” is a very broad category. It covers things that intentionally and legally added, as well as undesirable, illegitimate materials.

5.     First, food additives have been around for a very long time. In a sense, spices are “additives”—they have nothing to do with nutrition. So are food colorings. The Romans, to book tells us, used potash (salts of potassium) to wine, for example, to change its color.

6.     Second, some are bad for us, but others are probably good for us (as in the case of vitamins added to breakfast cereals).

7.     Third, sometimes it is hard to tell when an additive is good or bad—sometimes there is both risk and reward. Example of risk/reward: meat was once preserved by smoking and/or salting it. Risk: high blood pressure from the salt, maybe cancer from the smoke. Reward: food (and not starving!) during the winter, especially in cold climates.

8.     And other times new discoveries change our understanding of a product. Example: Romans adding lead to sweeten wine, through storage in lead containers.

But what about today? Why do we use additives?

1.     Convenience. Many prepared foods, such as salad dressings, breads, drinks (to name only a few) have additives that keep thinks in solution and also keep them fresher after opening. (To keep fats from going rancid, to retain moisture, to keep things from separating, etc.)

2.     Safety. Like smoking and salting of yesteryear, we also add preservatives to keep incorrectly stored foods from poisoning or killing us as easily.

3.     Consistency. People tend to want to have similar products from purchase to purchase; thickeners can be added to help.

4.     For health. White bread and breakfast cereals have vitamins added. Salt has iodine. Certain products help people with medical problems-sodium reduced (or free) salt substitutes, cholesterol-free, fat-free, and sugar-free foods, etc. (Note fat-free sour cream and ice cream)

5.     For aesthetic purposes—to increase the attractiveness of foods, either visually or through consistency. (♣♣)

So what’s the problem?? The problems can be:

1.     Deception. Sometimes additives can be used to trick people into thinking they are buying something they are not, or to use cheaper/inferior substitutes.

2.     Unintended side effects and health threats: coal-tar (aniline) dyes such as red dye #2, cyclamates, and safrole (part of sassafras oil used to flavor root beer). Lead. Aspartame (Nutrasweet) for people with PKU. The problem is complicated by the fact that new chemicals are being developed which humans and nature may have never seen before, so the long-term effects may not be known. ON THE OTHER HAND, nature itself is full of trace chemicals that are not fully understood.

3.     Also, some things may be more toxic at some times that other. Example: honey and infants. Or they may be hard to figure out, as in the case of pregnant women—no body wants the risk, animal studies may not work well, and epidemiological studies may return false .

And again, there are risks and benefits. Note the case of saccharine (debatable)., and maybe Nutrasweet (aka aspartame).

Even today the FDA has a GRAS list: “Generally Regarded As Safe”—NOT certified safe!!!

And some chemicals may help to reduce certain types of cancer (like BHT, which is a free-radical inhibitor). Maddeningly, some chemicals may HELP certain diseases, while aggravating others!

Some preservatives: 

1.     Nitrite: used in meat preservation, slows fats going rancid, contributes to flavor, a color fixative, and guards against botulism. However, there is some evidence that it could contribute to cancer, due to the formation of nitrosamines both during cooking and in the stomach.

(From Venture, Summer 1998 Vol. 1 No.2)

(available at http://www.nysaes.cornell.edu/fst/fvc/Venture/venture2_chemical.html)

2.     Sodium benzoate is used in fruit products, jams, relishes, beverages, dressings, salads, pie and pastry fillings, icings, olives and sauerkraut, and is against yeasts, some bacteria (foodborne pathogens but not spoilage bacteria) and some molds. Benzoic acid is the compound with the antimicrobial properties, and is found naturally in cranberries, prunes, greengage plums, cinnamon, ripe cloves and apples.

3.     Propionic acid and its salts, sodium and calcium propionates, are approved in the United States as GRAS (Generally Recognized As Safe) substances for food use. Their antimicrobial action is directed to molds and rope bacteria, with almost no effect on yeast, thus making them an ideal choice for products that use commercial yeast as an ingredient.

4.     Potassium sorbate is effective against yeasts, molds, and select bacteria, and is widely used at 0.025 to 0.10 % levels in cheeses, dips, yogurt, sour cream, bread, cakes, pies and fillings, baking mixes, doughs, icings, fudges, toppings, beverages, margarine, salads, fermented and acidified vegetables, olives, fruit products, dressings, smoked and salted fish, confections and mayonnaise.

Common sense is probably an excellent guide: where possible, fresh is better than preserved or “instant”.

 

Plants

Plants were probably domesticated about the same time as animals, about 10,000 years ago. 

“Fruit,” strictly speaking, in a botanical term.  It refers to plant parts derived from the ovary of the plant—so, technically, the tomato is a fruit!  In common usage, though, “fruit” means sweet, while “vegetable” means not “unsweet.”

Plants are different from animals in that they can make complex organic compounds from simple inorganic minerals, air, and water using sunlight for energy.  Animals must eat plants (or other animals) in order to live.

However, plants have fought back in some ways—some are poisonous or have spines.  Animals have adapted either by evolving work-arounds, such as immunity to certain poisons, or by other means such as cooking.  In the case of fruits, the plants are working WITH the animals; in a sense the plant is bribing the animal with the fruit to spread the seeds.

Plant evolution—angiosperm, gymnosperm.

Angiosperms are further divided into monocots (generally grasses, or some flowers like lilies, palm trees—they usually have parallel leaf veins and flower parts in multiples of threes), and dicots (most flowering trees, and small plants with palmate leave veins and flower parts coming in multiples of fours and fives)

Plant “organs”—Roots, stem, leaves, flower, fruit.

Important plant concepts:

Unlike most animal cells, most plant cells have rigid cell walls that help them hold their shape.  This is made of cellulose in cell walls, which humans can’t digest.  (cows and termites can, with bacterial help).  Cotton is 98% cellulose.

Lignin is important too—for structure. We shouldn’t eat it.  It is what makes plants woody.

Pectin is also important.  Found in fruits, it is what we use to make jelly “gel.”

Plants, especially herbs, also hold their shape with “turgor”—basically water pressure within the cell membrane.  Without it plants wilt.  Freezing a plant will often cause the cells to burst from water expansion and ice crystal damage.  Thus frozen plants are floppy.  §

Plant colors:  Plants are colored green by chlorophyll.  In some ways the chemical structure is similar to hemo- and myoglobin.  However, instead of iron, plants use magnesium at the center of the “daisy.”  Chlorophyll is incredibly important, because this is what drives photosynthesis. They are generally not water soluble.§

Carotenoids are yellow, orange, and reddish. They help green plants by collecting green and blue light energy and funneling it to the chlorophyll.  They also act as sunglasses to keep the system from overload.  They are fat soluble.  Beta carotene also acts as a precursor to vitamin A.§

Anthocyanins are water soluble.  They color many berries, red grapes, apples, red cabbage, radishes, and eggplant. §§

Another common color is browning—actually, similar to what makes us tan in the sun!  This is caused by enzymes that are released when the cells are damaged (or cut open).  Browning can be slowed by adding lemon juice, which slows the enzyme down. §§

Flavors:  Flavor is caused by chemical compounds within the fruit or vegetable. 

Astringency is what causes the “pucker” sensation.  It is often caused by tannins, as in the case of strong tea, tart red wine, or green fruit.  It is actually denaturing proteins (slightly) in the mouth via tanning.

Sweet and sour—sweet is caused by sugar in various forms.  Sour is caused by acids.

Bitter is caused by bases (and are often associated with poisons.  Coffee is an exception, and is an acquired taste).

Generally, the darker or more colorful a plant tissue is, the more nutritious it is.  Fiber is generally good, but can also reduce nutrient absorption in very large amounts.