I hope the notes below relating to ingredients of guacamole and salsa have been informative. Here are a few points/questions to consider:
1. Would the addition of chilies to guacamole prevent browning due to their high ascorbic acid content?
2. Browning or Maillard Reactions seem to be prevalent in nature. It is notable that organisms have developed defense mechanisms at all levels of evolution. I will continue to explore this topic in further detail as it pertains to other food.
3. The idea that spicy food affects our brains via the "pain" pathway is interesting to me. Are spicy foods proof that humans can experience 'pleasurable pain'?
4. I enjoyed thinking of fruits and vegetables as live organisms. It interests me to consider the breakdown of fruit in relation to processes of aging and dying. Enzymatic processes become random and chemical reactions upset the cells' balance leading to its death.
5. The effects of water crystallization on vegetables extends farther than that of simply freezing and thawing the water molecules. Uncontrolled water crystals actually puncture cell walls, thus attributing the limp texture of thawed vegetables. The physical structure is damaged and as a result the inner contents of the cells spill. When thawing frozen fruits and vegetables, one is losing more than just water content.
I'll limit my inquiries to five per session. Feel free to post your own thoughts.
Showing posts with label Lesson1. Show all posts
Showing posts with label Lesson1. Show all posts
Sunday, February 5, 2012
Friday, February 3, 2012
Chilies
Chilies are the most widely grown spice in the world. Capsaicin is the active ingredient that gives chilies their "spicyness." In terms of evolution, the chili peppers developed capsaicin as a chemical repellant against mammals, whose teeth grind up the fruit and destroy the seeds. Birds, on the other hand, are immune to capsaicin. They swallow the fruits whole and disperse the seeds widely.
Capsaicin is synthesized by the surface cells of the placenta - the pithy tissue that bears the seeds. It accumulates in droplets just under the cuticle of the placenta surface, not on the seeds, but it can coat the seeds quickly if that cuticle is placed under pressure. Some capsaicin enters the body of the fruit via the plant's circulation.
Capsaicin pungency is strongest before ripening. The hottest chilies are the ones picked around the time they start to change colors. There are different versions of the capsaicin molecule which account for the difference in pungency - quick and transient or slow and persistent.
The effects of capsaicin on the body are many. It affects the body's temperature regulation. It makes us feel hot thus activating our cooling mechanism of sweating and increased blood flow to the skin. Capsaicin increases metabolic rate and triggers brain signals to make us feel less hungry and more satisfied. (Weight loss, anyone?) Capsaicin is a skin and eye irritant. Its oily nature makes it difficult to wash off surfaces, so care must be taken when handling chilies.
To quench the burn, try something either cold (ice) or solid and rough (rice, crackers, a spoonful of sugar). Cold liquid cools the receptors below the tempertature at which they are activated. Cold water does not help as much because capsaicin is not water-soluble. Water distributes more capsaicin particles to the mouth. Cold milk is more successful. Carbonation in drinks adds to the irritation, alcohol has no effect. Rough solid food distracts the nerves with a different signal to the brain.
How do we rate chili peppers? The Scoville test for Capsaicinoids. Capsaicin is measured in parts per million and converted into Scoville heat units: 1 ppm = 15 Scoville heat units. The hottest peppers are the habaneros (200K - 300K Scoville Units), whereas the mildest are bell peppers (0 Scoville Units).
Research on chili peppers is ongoing. Healthwise, there is no evidence that chili peppers lead to ulcers. Instead, research sugggests that chilis may have health benefits. Capsaicin has been found to have anticoagulant properties. Chilis are high in vitamin C, as much or more than citrus fruits. Some research is focused on the understanding pain pathways (and pain-killers) via the capsaicin receptor in the brain, which is in the "pain" pathway.
Capsaicin is synthesized by the surface cells of the placenta - the pithy tissue that bears the seeds. It accumulates in droplets just under the cuticle of the placenta surface, not on the seeds, but it can coat the seeds quickly if that cuticle is placed under pressure. Some capsaicin enters the body of the fruit via the plant's circulation.
Capsaicin pungency is strongest before ripening. The hottest chilies are the ones picked around the time they start to change colors. There are different versions of the capsaicin molecule which account for the difference in pungency - quick and transient or slow and persistent.
The effects of capsaicin on the body are many. It affects the body's temperature regulation. It makes us feel hot thus activating our cooling mechanism of sweating and increased blood flow to the skin. Capsaicin increases metabolic rate and triggers brain signals to make us feel less hungry and more satisfied. (Weight loss, anyone?) Capsaicin is a skin and eye irritant. Its oily nature makes it difficult to wash off surfaces, so care must be taken when handling chilies.
To quench the burn, try something either cold (ice) or solid and rough (rice, crackers, a spoonful of sugar). Cold liquid cools the receptors below the tempertature at which they are activated. Cold water does not help as much because capsaicin is not water-soluble. Water distributes more capsaicin particles to the mouth. Cold milk is more successful. Carbonation in drinks adds to the irritation, alcohol has no effect. Rough solid food distracts the nerves with a different signal to the brain.
How do we rate chili peppers? The Scoville test for Capsaicinoids. Capsaicin is measured in parts per million and converted into Scoville heat units: 1 ppm = 15 Scoville heat units. The hottest peppers are the habaneros (200K - 300K Scoville Units), whereas the mildest are bell peppers (0 Scoville Units).
Research on chili peppers is ongoing. Healthwise, there is no evidence that chili peppers lead to ulcers. Instead, research sugggests that chilis may have health benefits. Capsaicin has been found to have anticoagulant properties. Chilis are high in vitamin C, as much or more than citrus fruits. Some research is focused on the understanding pain pathways (and pain-killers) via the capsaicin receptor in the brain, which is in the "pain" pathway.
Ripening
Ripening is the fruits last intense phase of life before starting to decay. Ethylene is the single trigger for the ripening enzymes to go into action.
There are two styles of ripening among fruits:
1. Climacteric - the fruit stimulates itself by producing more ethylene and begins to respire (O2 consumption and CO2 production) much faster than before. These are fruits that are harvested mature but green, and will ripen on their own. Examples are: bananas, avocados, pears, and tomatoes. (Note: climacteric fruit will still taste better if allowed to ripen on the plant).
2. Nonclimacteric - fruits that don't respond to ethylene in a positive feedback loop. They ripen gradually, don't store sugars as starch, and depend on their connection to the parent plant for ripening. Examples are: pineapples, citrus fruits, most berries, and melons. These are best when picked as ripe as possible.
There are two styles of ripening among fruits:
1. Climacteric - the fruit stimulates itself by producing more ethylene and begins to respire (O2 consumption and CO2 production) much faster than before. These are fruits that are harvested mature but green, and will ripen on their own. Examples are: bananas, avocados, pears, and tomatoes. (Note: climacteric fruit will still taste better if allowed to ripen on the plant).
2. Nonclimacteric - fruits that don't respond to ethylene in a positive feedback loop. They ripen gradually, don't store sugars as starch, and depend on their connection to the parent plant for ripening. Examples are: pineapples, citrus fruits, most berries, and melons. These are best when picked as ripe as possible.
Thursday, February 2, 2012
Enzymatic Browning
Ever wonder what happens when a fruit or vegetable discolors soon after being cut? Here is the answer from On Food and Cooking, The Science and Lore of the Kitchen, p. 269:
"[The] discoloration is caused by three chemical ingredients: 1- and 2-ring phenolic compounds, certain plant enzymes, and oxygen. In the intact fruit or vegetable, the phenolic compounds are kept in the storage vacuole, the enzymes in the surrounding cytoplasm. When the cell structure is damaged and phenolics are mixed with enzymes and oxygen, the enzymes oxidize the phenolics, forming molecules that eventually react with each other and bond together into light-absorbing clusters."
It is a similar principle to when people react to sun exposure and become tan.
So why does lemon juice prevent browning?
Browning enzymes work very slowly in acidic conditions. Aside from its acidity, lemon juice also has ascorbic acid (Vitamin C) which has antioxidant properties.
"[The] discoloration is caused by three chemical ingredients: 1- and 2-ring phenolic compounds, certain plant enzymes, and oxygen. In the intact fruit or vegetable, the phenolic compounds are kept in the storage vacuole, the enzymes in the surrounding cytoplasm. When the cell structure is damaged and phenolics are mixed with enzymes and oxygen, the enzymes oxidize the phenolics, forming molecules that eventually react with each other and bond together into light-absorbing clusters."
It is a similar principle to when people react to sun exposure and become tan.
So why does lemon juice prevent browning?
Browning enzymes work very slowly in acidic conditions. Aside from its acidity, lemon juice also has ascorbic acid (Vitamin C) which has antioxidant properties.
Avocado
Most avocados in the US are grown in Southern California. The most common variety is the Haas avocado, which belongs to the Guatemalan group, which means they are not very cold-tolerant and can suffer injury in the fridge.
Avocados don't ripen until after they are picked. To ripen an avocado, keep at room temperature in a paper bag with either an apple or a banana. These fruits emit ethylene, which aids the ripening process. Do not place an avocado in the fridge while unripe. It will not ripen. Once ripen, the avocado can be stored in the fridge for several days.
To prevent the avocado from browning, add an acidic ingredient such as lemon juice, or keep in airtight wrapping.
Avocados don't ripen until after they are picked. To ripen an avocado, keep at room temperature in a paper bag with either an apple or a banana. These fruits emit ethylene, which aids the ripening process. Do not place an avocado in the fridge while unripe. It will not ripen. Once ripen, the avocado can be stored in the fridge for several days.
To prevent the avocado from browning, add an acidic ingredient such as lemon juice, or keep in airtight wrapping.
Alliums
The Allium genus includes: onions, garlic, and leeks.
The strong, often pungent, flavor of the onion comes from its defensive use of sulfur.
The alliums stores sulfur as chemical ammunition, which float in the cell fluids. An enzyme trigger is held separately in a storage vacuole. When a raw onion, garlic, or leek is chopped, chewed, or otherwise physically damaged, the enzyme trigger is released from its vacuole, breaks the ammunition molecules in half to produce sulfurous molecules, which are strong-smelling and irritating. Some of these molecules are volatile, so they continue to react into other compounds. Exposure to oxygen will affect the reactions and thus the flavor of the raw allium. Chopping, pureeing, and pounding will produce varying results.
If the allium is to be consumed raw, it's best to rinse it first to remove the sulfur compounds, since they will continue to react and become harsher with time and exposure to air.
Lacrimator is the sulfur compound that causes the eyes to water. This compound escapes the onion and goes into the eyes and nose of the onion cutter, where it attacks nerve endings directly. Its effects can be minimized by chilling the onions in ice water 30-60 min.
The method of cooking will also affect how the sulfur compounds react, thus producing a range of characteristic flavors.
Cooking at high temperatures in fat will give the strongest flavors. Blanching garlic inactivates the flavor-generating enzyme, so it gives a milder flavor.
The strong, often pungent, flavor of the onion comes from its defensive use of sulfur.
The alliums stores sulfur as chemical ammunition, which float in the cell fluids. An enzyme trigger is held separately in a storage vacuole. When a raw onion, garlic, or leek is chopped, chewed, or otherwise physically damaged, the enzyme trigger is released from its vacuole, breaks the ammunition molecules in half to produce sulfurous molecules, which are strong-smelling and irritating. Some of these molecules are volatile, so they continue to react into other compounds. Exposure to oxygen will affect the reactions and thus the flavor of the raw allium. Chopping, pureeing, and pounding will produce varying results.
If the allium is to be consumed raw, it's best to rinse it first to remove the sulfur compounds, since they will continue to react and become harsher with time and exposure to air.
Lacrimator is the sulfur compound that causes the eyes to water. This compound escapes the onion and goes into the eyes and nose of the onion cutter, where it attacks nerve endings directly. Its effects can be minimized by chilling the onions in ice water 30-60 min.
The method of cooking will also affect how the sulfur compounds react, thus producing a range of characteristic flavors.
Cooking at high temperatures in fat will give the strongest flavors. Blanching garlic inactivates the flavor-generating enzyme, so it gives a milder flavor.
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