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Originally Posted by scott123
Crisco is oil that's been chemically altered to make it impervious to air/oxidation/randicity. It lasts for years..
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The "chemical process" is hydrogenation (hot oil is pumped into a tank containing nickle and hydrogen gas is bubbled through it until it reaches a specific concentration - then it is filtered to remove the nickle and whipped to introduce about 20% air by volume as it cools and is then deposited into containers while still soft). Since vegetable oils are low in saturated fats - they are liquid at room temp - hydrogenation alters a portion of the mono and poly unsaturated fats to mimic saturated fats (these are the trans fats) and cause them to be solid at room temp.
Crisco is only "partially" hydrogenated (not all of the mono and poly unsaturated fatty acids have been converted from CIS to Trans configuration) - therefore it is not
impervious to oxidation or rancidity - although it is somewhat reduced. Crisco will, depending on how many times the can is opened and exposed to oxygen, go rancid in 12-18 months - not a matter of years.
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Originally Posted by scott123
Most commercial lard has been hydrogenated in the same fashion..
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True - of most TUB lard you find on supermarket shelves (like Armour). Another lard varient is "leaf" lard - and there are two kinds ... one refers to the lard from around the kidneys and the other is uses to refer to lard that has been rendered and filtered and formed into blocks like butter - and is in the refrigerated case with the butter - not on a shelf in a bucket like Crisco.
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Originally Posted by scott123
Butter, on the other hand, not only contains a less saturated/less impervious fat, it contains milk solids that make is especially prone to decay. Crisco/lard- sold at room temp. Butter is sold in the refrigerated case. That should tell you something. Butter can't stand a chance at room temp but criso/lard can.
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Different fats have different melting points and melting ranges - butter has a very low melting point and narrow melting range - Crisco and lard have higher melting points and a broader melting range - which is why when you're looking for both flakey and tender in a recipe for something like a pie crust you will see both used. Actually - regarding saturated fats - butter is about 62% with 33 mg/tbsp cholesterol - lard is only about 40% with 12 mg/tbsp cholesterol.
I try to watch my fat intake (regardless of the source - animal or vegetable) but knowing the facts is why I don't freak out when I use lard once in a while. The lard that goes into the biscuits is probably healthier for me than the butter I'll definately put on them with a more liberal hand.