Blog Directory - Blogged foodliterate: December 2007

Sunday, December 23, 2007

The Plot Thickens

So, I've spent some time on the simple saccharides and now its time to move to the more complex carbohydrate structures. Although I've touched on these before, today we're going to dig a little deeper.

Polysaccharides are chains of saccharide molecules which form polymers. They can range from a few hundred to many thousand molecules long and can be straight or branched chains. The majority of the polysaccharides that we are familiar with are plant based. Plants, via photosynthesis, take carbon dioxide (CO2) from the air, water (H2O) from the ground and energy from the sunlight (through cholorphyll) and convert it to oxygen (O2) and carbohydrates to store energy (starches) and provide structure (cellulose).

Starch is comprised of glucose chains with alpha linkages (molecules are attached at the first, aka alpha, carbon) and comes in two types of structures: straight chains (amylose) and branched chains (amylopectin). Plants store these molecules in granules in the cells. Starches are not sweet, aren't solubile in cold water, but do swell (gelatinize) when the solution is heated. We start to break down starches through our saliva which contains amylase (the suffix -ase denotes the enzyme). Amylase breaks the starch into smaller units but this process stops once the stomach acids become involved; they inactivate the enzyme. The final breakdown of starch occurs in the small intestine where pancreatic enzymes finish the job and the glucose molecules are absorbed into the bloodstream.

Now, fiber is also a polysaccharide, and it is differenciated into soluble and insoluble forms. Insoluble fiber is characterized by chains with beta linkages (molecules attached at the second, aka beta, carbon). This is a small but significant difference because we can't break these linkages and insoluble fibers reach our large intestine intact. They include cellulose, hemicellulose and ligin and are found in whole grains, bran, and vegetables. Insoluble fibers leave our body in essentially the same form they entered, that's why they are important - they add bulk to our diet and help carry waste out.

Soluble fibers, as you've probably guessed, are soluble in water and include pectin and gums. Soluble fibers are also chains, but instead of sugar molecules, they are sugar acids. You find them in items like citrus fruits, apples, strawberries, oats, legumes, guar and barley. Although we can't break soluble fiber down, the bacteria in our gut can and do; this fermentation provides us with beneficial short-chain fatty acids.

So, now you know the basics of the polysaccharides and how they are processed in the body; next time I'll discuss how and why these are used by food technologists in your favorite foods. Until then - stay saucy!

Tuesday, December 11, 2007

Visions of Sugarplums

In the spirit of the season and while we are discussing sugar and carbohydrates, I thought I'd share a couple of recipes for holiday treats.

Not many people have had an actual sugarplum, but they don't only exist in book & song. A sugarplum was originally a candied plum; a way to preserve the taste of summer all year long. Somewhere along the way it became a mixture of dried fruits and nuts. And as far as Christmas candy goes, this is pretty healthy!

1 cup pitted dates (or figs)
1 cup toasted almonds
1 cup dried apricots
1/3 cup pistachios
1/3 cup candied ginger
2 tbsp grated orange zest (or lemon)
2-3 tbsp orange juice (or lemon)
Demerara sugar (or other large granular sugar)

Add everything except orange juice & sugar to a food processor & process until minced. Add juice until mixture sticks together. Form into 1" balls and roll in the sugar. Place in small, fluted cups or arrange on a platter.

This is just a basic recipe - feel free to get creative. You can add prunes, cherries, raisins, coconut, etc. Add what you like and what makes you happy. Next time you hear the Nutcracker Suite you really will have visions of sugarplums in your head!

Lollipops are so simple, but they are interesting chemically. There is a finite amount of sugar you can dissolve in water, called a saturated solution (just over 200g sugar per 100g of water at 20°C). But as you increase the temperature of the water, you can increase the amount of sugar in solution forming a super-saturated solution. Unfortunately super-saturated solutions aren't very stable; the sugar wants to recrystallize. Since lollipops are amorphous, not crystalline, this is a problem. Luckily, it is one that isn't too hard to solve. For starters, wet down the sides of your pot to keep crystals from developing. These can become "seed crystals"; if they fall in the super-saturated solution they can cause the crystals to redevelop. We also add corn syrup (full of glucose & fructose molecules) to run interference with the sucrose molecules and break up their party. And lastly, don't stir the solution once it hits a boil; agitation is also something that causes the sucrose to recrystallize. We want clear, smooth lollipops not gritty, opaque ones.

1 cup sugar
1/3 cup light corn syrup
1/2 cup water
1/2 to 1 tsp Flavored Oil (cherry, cinnamon, peppermint, anise) of your choosing
Food coloring as desired
Candy thermometer
Paper or wooden lollipop sticks
Silpat or oiled baking sheet or oiled marble slab

Stir sugar, corn syrup, and water in a heavy saucepan. Bring to a boil stirring often and brushing down the sides of the pan with a wet pastry brush. Once boiling, cover and let boil 2-3 minutes. Uncover and put in candy thermometer, bring to 290°F. Remove from heat, add color & flavored oil; cool to 280°F. Spoon onto silpat or oiled surface (or into molds). Add sticks while still hot & pliable; spoon a small amount of candy over the stick to help hold it in place. Let cool completely.

I hope you are inspired to try one (or both!) of these recipes and that you've learned something new. I've had fun with all of this sweet talk but I promise to move on from sugar in the next post, before we all get cavities from the sugar overload!

Wednesday, December 5, 2007

Sugar Sugar

Ready for something sweet - of course I'm talking sugar, aka sucrose. Let's get into some detail about this most common of saccharides (disaccharide to be specific). It seems silly to ask what is so interesting about sugar, but I think it is interesting.

We evolved (or if you prefer were created) needing to find calorie dense food and although food is now easily obtained and readily available, we haven't out grown that craving. The sense of sweetness was used to identify food that was ok to eat (there aren't any naturally occuring toxic substances with an apparant sweet taste, although there are plenty of man-made ones) and had higher calorie content.

I'm sure you all learned that we experience 4 taste sensations (I'll tell you about a 5th in a future post): sweet, salty, sour, and bitter. All products, sugar included, exhibit each of these tastes at some level. If you make a weak solution of sugar it will taste more sour than sweet. Sweeteners are are rated on their relative sweetness, so they can be compared, and the reference standard for the comparison is usually sugar (sucrose). Chemistry alert! All compounds that possess a sweet taste have a bipartate system capable of hydrogen bonding (with the taste receptors on our tongue) called a 'glycophore'. If you want to understand how that functions in the perception of sweetness click here. And if you are really hard core & want to know about the chemistry of taste recognition for all 4, try this.

So where does sugar come from? Sugarcane & sugar beets. The sucrose they yield is the same; there is no difference chemically, structurally or physically. We have 4 categories of sugar here in the U.S.: granulated, brown, liquid and specialty. Granulated is pretty self-explanatory; it is pure (99.8%) sucrose and comes in sizes ranging from large to powdered (coarse, sanding, extra fine, fruit, bakers special, 6X, 10X). Brown sugars are usually found as light or dark, but industrially we also have coated and free-flowing. Brown sugars are granular sugar that has been covered with cane syrup, which is why it is so sticky and gets so hard after being exposed to humidity & air. Liquid sugar is exactly what it sounds like, a solution of sucrose in water. It is used industrially and commercially, but it is unlikely that you will find it on a grocery shelf as it is not stable (microbially) for long periods of time. And specialty sugars, wow - there are quite a few: sugar cubes, fondant, invert, flavored, molasses, etc. Of these, molasses is probably the most interesting since everyone is familiar with it, but know very little about it. Molasses is the viscous liquid remaining at the end of processing when no more sugar can be crystallized from the product; this is known as 'blackstrap molasses'. New Orleans molasses is a by-product of open-kettle boiling, once the crystals have been centrifuged out, the remaining liquid is bottled.

Well my sweets, before I go into a sugar crash, I think it is time to close this post. I'll stay on saccharides next post, but will talk about some of its other forms. Bye!