Sugars and Fats

Spring, 2009

Sugar

According to Biochemistry textbooks, a sugar is a caloric sweetener. Caloric means that it supplies energy or calories.

Name that sugar

Glucose (aka dextrose) molecular formula

C6H12O6

Fructose molecular formula C6H12O6

Galactose molecular formula C6H12O6

These are monosaccharides

Isomers- molecules that share the same molecular formula (in this case C6H12O6)

Glucose and galactose are geometric isomers because that contain the same atoms attached in the same groupings, but the groups point in different directions. (in this case the OH on the left most carbon point down in glucose and up in galactose)

Disaccharides

There is about 1 tablespoon of lactose in an 8 oz. glass of milk.

Lactase

A protein and enzyme that is made up of 1927 amino acids. It is found in the intestinal epithelium (microvilli) and is responsible for hydrolyzing the bond between the glucose and galactose. Only after the disaccharide is split into two monosaccharides can the body use the sugars as fuel.

Evolution and Lactase

A baby produces lactase from birth. The enzyme is needed to split the lactose in breast milk. After about five years of age most children stop producing much if any lactase. Without lactase your body can not break down lactose. Unfortunately, the lactose doesn’t just get excreted from the body, but bacteria in the intestines picks up where lactase leaves off.

There is a reason why the work of intestine bacteria is unfortunate. When bacteria splits lactose, the process releases gas and draws water to the intestines.

Sucrose is first digested in the stomach by stomach acid. Any remaining sucrose split into glucose and fructose by sucrase in the walls of the intestines.

Most mammals will eat food sweetened with sugar.

Four basic tastes: sweetness, sourness, bitterness, saltiness. The ability to distinguish sweet provided an evolutionary advantage.

Sweet=Good=ripe fruit

Bitter=alkaloid=poison

Sour=acid=not ripe fruit

This is your brain on glucose

The brain depends on a minute by minute supply of glucose from the bloodstream for fuel. There is no storage capacity for the glucose in the brain. A 50% drop in normal glucose levels causes symptoms of brain dysfunction to occur. A 25% drop in normal levels may result in a coma.

Sucrose is not a necessary part of a well balanced diet. Today’s intake of sugars is characterized as overconsumption.

Country per capita annual consumption

Cuba 60-80 kg (130-180 lbs)

Brazil, Fijii, Australia 50 kg (110 lbs)

Europe, Americas 30-40 kg (70-90 lbs)

China 6.5 kg (14 lbs)

Even lower in many African countries

History of sugars

Christopher Columbus introduced sugar cane to Hispaniola during his voyage in 1492. The Portugese introduced the plant to Brazil in 1520. The British, Dutch, and French planted sugar cane in the West Indies in 1640. The crops were tended and sugar extracted by the indigenous people until most of them died from Old World diseases.

Great Circuit

2/3 of all African slaves brought to the Americas worked on sugar plantations.

High Fructose Corn Syrup

As of 2004, High Fructose Corn Syrup became the most commonly used sweetener in the US. (55% HFCS, 45% sucrose)

Why?

Corn is subsidized and it cost there is a quota on the amount of sugar imported into the US.

Corn starch glucose fructose syrup

Enzymatic process developed in 1970’s.Start with corn starch (not sweet) and treat with alpha-amylase with produces short chains of glucose (oligosaccharides). The oligosaccharides are treated with glucoamaylase which breaks the chains into individual glucose molecules. Finally glucose isomerase converts glucose to a mixture of 42% fructose, 50-52% glucose, and some other sugars.

oligosaccharide

Polymers of Glucose

Joining the glucose molecules below are β-linkages. Our bodies can not break down the β-linkage in order to use the glucose as fuel. The β –linkages also make the polymer insoluble in water. This polymer is called cellulose or in nutritional speak “fiber”.

Joining the glucose molecules below are α-linkages. α-linkages make the polymer soluble in water. Also our bodies can split the polymer into individual monomer units in order to use the glucose molecules for fuel. These polymers are called starches. They are made by plants and animals.

Amylose and amylopectin = plant starchglycogen = animal starch

The A-H B model of sweetness

Artificial Sweetners

Glycol is not safe to eat

You may have already eaten this today

Lipids

• Fatty acids• Glycerides

monglyceridesdiglyceridestriglycerides

• Nonglyceridessphinglolipidssterolsterpeneswaxes

Fatty acids

Monounsaturated Fat

Glycerides

What’s this?

Steroids

Terpenes

Vitamins– Which are water-soluble and which are not?