Skip to main content

Ask Carb Diva: Questions & Answers About Food, Recipes, & Cooking, #154

Linda explores food facts, folklore, and fabulous recipes one ingredient at a time.


Difficult Times

The West Coast of the United States is ablaze, with more than 100 wildfires and (as of Saturday the 12th of September), 6,200 square miles consumed. Unfortunately, the fires are not confined to the wilderness. They are encroaching on urban areas; one town in Washington State has all but been wiped off the map.

As I write this, the sky is yellow, the birds have stopped flying, and the air is a mix of wood smoke and toxic chemicals from the associated home and industrial fires (arsenic, heavy metals, copper, lead, transformer fluid, brake fluid, fire retardant, etc.) The air quality index in my little corner of the world is 202—worse than Delhi and 2nd highest on the planet. In the states of Washington/Oregon/California at least 28 people have died and tens of thousands have been forced to evacuate their homes.

All this plus COVID19, racial unrest, demonstrations, massive unemployment, and looting.

Your reports of good news would be greatly appreciated.

Let's Begin

If you're an old friend, you already know how this works. But, if this is your first visit, let me introduce you to my kitchen.

Each week I receive questions about food ingredients, cooking or baking terms or methods, requests for recipes, and queries about nutrition. Just about anything food-related has been covered here.

I'm sharing this past week's questions and my responses; it happens every Monday. Want to join in the fun? You can leave your question in the comments below, and next week the answer will be right here. It's that easy.

Can You Explain the Various Cooking Oil Temperatures?

"Have you written a piece on temperatures of frying as applies to; Oils, margarine, Country Crock, salted butter or grease? I am having issues getting it right. I am amazed at the burn temp differences with different oils. Seems oil should be oil."


Eric, what you're referring to is smoke point, the temperature at which your cooking oil begins to send out smoke signals. Oil shimmering in a ripping-hot pan can be the perfect way to create a tasty stir-fry or a stovetop-seared steak. But beyond a certain point, fat breaks down, releasing free radicals into the air and a chemical substance (acrolein) that gives foods a burnt taste, makes your eyes water, and stinks up your kitchen.

Are all oils the same and if not, why not? The problem is that some oils are refined (to remove impurities) and some contain a higher amount of "free fatty acids."

I've put together a chart that shows the smoke point for most of the oils you might ever (want to) use, but I'd be derelict in my duty if I didn't take the time to issue some warnings. Just because you can cook with all of these, that doesn't mean that you should. And that is why I have also included numbers for the percentage of saturated, monosaturated, and polyunsaturated fat in each. If you don't know what that means don't worry, I'll explain that too.

Type of OilSmoke PointSaturated Fatty Acids (not the good stuff)Mono Fatty AcidsPolyunsat. Fatty Acids

Extra virgin olive oil















Vegetable shortening













































Palm kernel oil










Rice bran





Refined safflower










Saturated, Monosaturated, and Polyunsaturated Fats

What do these words mean? It's chemistry (definitely not my best subject), but I think I can explain. There are three major groups of fats; like the Clint Eastwood spaghetti Western there are the good (monosaturated and polyunsaturated), the bad (saturated), and the ugly (trans fats).

Monosaturated and Polyunsaturated

Oils that contain unsaturated fats are typically liquid at room temperature but start to turn solid when chilled. Olive oil is a good example of this. What is the difference between monounsaturated and polyunsaturated? A chemist would tell you that the difference between these two fats lies in their structures.

Monounsaturated fats contain one double bond in their structures. On the other hand, polyunsaturated fats contain two or more double bonds in their structure.

What does this mean? Well, simply put there are two methods of extracting oil. First is what we call the cold-press method—the monounsaturated oils. ‘Mono’ oils such as:

Scroll to Continue
  • extra virgin olive oil,
  • peanut oil, and
  • sesame oil.

These oils are made without the use of chemicals. Squeeze, press, extract. Done.

Science and innovation have helped us to discover a second set of healthy oils—the polyunsaturated oils.

These oils are manufactured using heat and solvents to extract the oil from the seed or food product. Examples are

  • walnuts,
  • sunflower,
  • sesame,
  • soybean,
  • sunflower,
  • corn,
  • canola, cottonseed, and
  • safflower oils

Saturated Fats

Saturated fats occur naturally in many foods—those made from animal products. A diet heavy in saturated fats will raise your total cholesterol level. And (more bad news), foods high in saturated fats and also typically high in calories.

Examples are:

  • fatty beef,
  • lamb,
  • pork (which of course includes bacon),
  • poultry with skin,
  • beef fat (tallow),
  • lard and cream,
  • butter,
  • cheese and
  • other dairy products made from whole or reduced-fat (2 percent) milk.

In addition, many baked goods and fried foods can contain high levels of saturated fats. Some plant-based oils, such as palm oil, palm kernel oil, and coconut oil, also contain primarily saturated fats.

The American Heart Association recommends aiming for a dietary pattern that achieves 5% to 6% of calories from saturated fat. That means, for example, if you need about 2,000 calories a day, no more than 120 of them should come from saturated fats. That’s about 13 grams of saturated fats a day. One tablespoon of animal fat (bacon grease, duck fat, lard) is 116 calories and 13 grams of fat.

Trans Fats

I won't go into great detail on these because I am not including them in the list of potential cooking oils.

Trans fats are a man-made substance—an industrial process that adds hydrogen to vegetable oils to make them solid at room temperature. The benefit is that these oils spoil at a much slower rate—slower spoilage means a longer shelf-life for goods made with trans fats. And trans fats used for deep frying don’t have to be changed as often. You are probably wondering why this is a bad thing?

Trans fats are considered by nutritionists to be the worst of all fats—the Frankenstein of dietary substances. Trans fats (also called trans-fatty acids or partially hydrogenated oil) are truly a cholesterol double-whammy. They raise the bad (LDL) cholesterol and lower the good (HDL) cholesterol.

Trans fats have no place in your diet.

Do I REALLY Have To Wait for the Oven to Heat Up?

Not very long ago I was asked by "someone" to show him/her how to make scones. I whipped out my recipe, demonstrated how to measure out the ingredients, cut the butter into the flour, mix in the cream, and then gently knead (not too much). Meanwhile, the oven was preheating. The correct temperature is 425°C, but my student in the kitchen placed the pan of scones into the oven when the temperature was still in the neighborhood of 375°F. The reason? "I got tired of waiting."


What's the harm? Well, for starters, ovens heat from the bottom up; an oven that is not fully preheated will be hotter on the bottom than on the top. Place those scones in a less-than-perfect oven and the bottoms will be burnt by the time the top of the scone is fully cooked.

Also, the blast of heat from a properly-prepared oven is the magic that makes baked goods (like scones) rise tall and proud (and fluffy). Moisture and gas trapped in the dough expand with heat. It's science, and it works.


Conventional vs. Convection Oven

"Yesterday, I made one of the recipes you featured in response to Bill's query regarding tilapia recipes. After ensuring I had all the ingredients, I read the 'how to' part. It was then I discovered the author gave instructions for a convection oven. I'd never come across that stumbling block before (I have a conventional oven). So before I began, I Googled conversion rates for temp and time. Here's my question: what is the difference between convection ovens and conventional ones? Is there an advantage to one over the other? And, finally, could you provide conversion rates from convection to conventional (and vice versa) with regard to temperature and cook time?"

Shauna, what a great question. I don't have a convection oven either, so I had to do some research (the best part of this gig if you ask me). Conventional and convection ovens can be either gas or electric—the difference is not the source of heat but the way in which the heat is distributed. In a conventional oven, the warmth radiates from a heating element. Convection ovens have a fan that circulates the hot air. If you've ever seen an air fryer, it's basically a countertop convection oven. That sounds great, doesn't it?


  • Faster cooking (20 to 30 percent faster)
  • More even heat distribution
  • Consistent heat (no hot or cold spots).
  • Circulating air helps produce a crisp(er) crust on bread, or oven-baked chicken, etc.
  • Preheating is not necessary

However, there are a few drawbacks to consider.


  • Standard recipes need to be converted. Times and temperatures need to be reduced. There are actually 3 methods of doing this (we'll discuss that in a minute).
  • You might need to purchase new cookware (low-sided pans, and containers that allow at least 2 inches from the sides of the pan to the oven walls.)
  • Great for baking cookies or bread; not recommended for cakes or cupcakes.

Some oven manufacturers suggest reducing the cooking time by 25 percent. Others suggest reducing cooking temperatures by 25°F. And (just to make things complicated) there is a third philosophy that suggests reducing both—by just a little. Here's a chart:

Source: Gourmet Sleuth

Source: Home.HowStuffWorks

FoodConventionalConvection Option 1Convection Option 2Convection Option 3

Roasted turkey (~12 pounds)

350°F for 3.5 hours

350° for 2.75 hours

325°F for 3.5 hours

315°F for 3 hours

Baked ham (~6 pounds)

350°F for 1.5 hours

350°F for 70 minutes

325°F for 1.5 hours

340°F for 80 minutes

Meatloaf (1.5 pounds)

350° for 1 hour

350°F for 45 minutes

325° for 1 hour

340°F for 50 minutes

Baked potatoes

400°F for 45 minutes

400°F for 35 minutes

375°F for 45 minutes

385°F for 40 minutes

Roasted vegetables

400°F for 55 minutes

400°F for 40 minutes

375°F for 55 minutes

385°F for 48 minutes


350°F for 12 minutes

350°F for 9 minutes

325°F for 12 minutes

340°F for 10 minutes

We're Organized

Did you know that there is a Table of Contents for this series? I have created an article that provides a detailed listing of each question I've received. It's broken down by category, and within each category, the questions are listed alphabetically. Each question is actually a hotlink back to the original post.

Here's a link to that Table of Contents.

I have also cataloged all of my personal recipes that I have shared with you in this weekly Q&A series and in all of my other articles as well. The link to that Index is here. There are hotlinks to each recipe and this will be updated as new recipes are shared.


Let's do this again next week. If you have questions about foods, cooking techniques, or nutrition you can ask them here. If you are in search of an old recipe or need ideas on how to improve an existing one I can help you. If you want to learn more, let's do it together. Present your questions, your ideas, your comments below. Or, you can write to me personally at this email address:

And, I promise that there will always be at least one photo of a kitty in every Monday post.

© 2020 Linda Lum


Linda Lum (author) from Washington State, USA on September 18, 2020:

Doris, I never knew that Chernobyl had impacted the United States. I don't have any gemstones, but I had some of the ash (my husband worked there, and I spent a day in the field about a year after the eruption).

Doris James MizBejabbers from Beautiful South on September 17, 2020:

Linda, you asked if we were impacted in Arkansas by the eruption of Mt. St. Helens in 1980. I honestly don't remember, but I do know that we were impacted by 1986 Chernobyl meltdown for several years. The tops of our tall trees, like oaks, browned in the summertime months before it was time for the leaves to fall in autumn (for several years).

By the way on a trip to Seattle, I bought a ring with a lovely Helenite or whatever they are now calling the stone made from the ashes of Mt. St. Helens. Such a beautiful green stone; people ask me if it is a real emerald.

Convection ovens are no big deal, at least my small one is more of a glorified toaster oven (great for pizza).

Denise McGill from Fresno CA on September 16, 2020:

Yes. When the sky turned dark and all the automatic lights came on at 2 in the afternoon I was surprised. The sun has been gone for days and when it does peek through it is a surreal orange. The only good thing is that the heat has let up. Not enough sunlight can get through, I guess. The AQI here is very high and even the pets are advised to stay indoors. My eyes are burning too.

Stay safe my friend.



Linda Lum (author) from Washington State, USA on September 16, 2020:

Oh Denise! How frightening for you and your friends. I'm glad that they and you are safe.

There have been fires in our county (but Pierce County is huge geographically. It covers 1800 square miles). Nothing close to us, but the smoke is still horrific. As I write this, the AQI has finally fallen below 200, but my throat is burning and the sky is still a surreal shade of yellow. I'm sure you're very familiar with what that is like.

Denise McGill from Fresno CA on September 16, 2020:

I've often wondered about convection ovens but didn't spend too much time on it because I don't have nor ever had one. Good to know what to do if I should ever come across one. I haven't been doing much baking during this summer because firing up the oven also heats the house and we've had record heat waves this summer here in the central valley of California. We had the Creek Fire come within a few miles of us and we got two standby alerts for possible evacuation but it looks like those great heroes (the firefighters) have contained the fire about 12% so far and our evacuation notice is lifted. I have one artist friend who was so close to the fire that they were told to gather their things and be ready to leave at a moment's notice. He and his wife took many paintings off the walls and off the stretchers so they could roll them up and put them in the car, just in case. Gratefully, the evacuation notice was lifted for them yesterday. Still, they say the fire won't be fully contained until mid-October (4 weeks from now). I think that's good news.



Linda Lum (author) from Washington State, USA on September 14, 2020:

MizB, thanks for writing. Your comments are usually more informative than the original article! Perhaps there is a difference between counter top convection ovens and the full-size ranges. I have no idea and, honestly, I'm too danged old to learn. I won't buy a convection oven--I'm just too set in my ways.

Thank you for your kind words. My throat still feels like raw meat and I feel groggy even after a somewhat sound sleep.

Your comment that the smoke has made its way to Arkansas reminded me of May 18, 1980. Were you impacted by the eruption of Mount St. Helens? Now THAT was some serious smoke/ash. My brother was in Spokane, Washington (eastern side of the State) at the time and he says that at noon (the eruption was at 8:32 a.m.) the sun was completely blotted out; it looked like nighttime (end of the world). We had to wear masks outside and everything was covered with gray ash, as fine as flour but abrasive.

Doris James MizBejabbers from Beautiful South on September 14, 2020:

That is a surprise. It looks like pure lard isn’t as unhealthy as some of the vegetable oils are. My mother cooked everything in lard and didn’t discover vegetable oil until I was in my teens. Yet, I always had low cholesterol until past my mid life when, I guess all that red meat my husband craved caught up with me.

Somebody lied to us. I’ve used smaller convection ovens for 15 or 20 years whenever I can because they are much more economical to operate than my big gas oven. I’m on my 3rd electric one, and not one of them has needed the cooking time or temperature reduced. In fact the one I have now sometimes requires adding about 25 degrees or another 10 minutes, or both, except for cookies. I expect to add time and temp to my gluten-free baking, of course, but Larry bakes regular biscuits for himself, meatloaf, chicken etc. I wonder if they are referring to full sized convection ovens.

I really feel for all of you on the west coast. The past week I’ve had lung congestion problems so bad I’ve been using an inhaler. Yesterday the weatherman explained that the smoke from the wildfires has made it all the way to Arkansas. Thank goodness, I don’t have real asthma, or I might be in trouble. I’m so sorry for everyone affected by these fires, especially those who have lost loved ones.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Mary, I've never had Coffee Mate (but I know what it is). I'll have an answer for you next week--I'm certain we can come up with a recipe or two.

My prayers for your son and his girlfriend and your sister's friend. So much sadness and strife. Yes, I think many will suffer for years to come once all of this is behind us. It's been quite a year.

Mary Wickison from USA on September 14, 2020:

I feel so overwhelmed by the fires raging on the west coast. I have family in California. My sister's friend had two of her family die in the fires. I have told my son and his girlfriend to roll up damp towels and put them under the doors to try and keep the smoke out. I feel so powerless not being able to help. Other than telling them I have space here for them if they can get a flight out.

This year has been awful for so many people. Many will suffer the effects of PTSD for some time, I fear.

You've answered a question as to why my biscuits/scones are short. Like, your student, I don't wait long enough for the oven to preheat.

I have a question for an upcoming Q&A. When I was in the States my sisters had a flavored Coffee Mate liquid. Is this something I can make at home? I think they had a vanilla and a hazelnut. It made a nice (occasional) change from milk or cream in my coffee.

Take care and stay safe.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Thank you, Pamela. It is a worry. Our Pastor and his family had to evacuate their home last week. That fire is now 100 percent contained.

Pamela Oglesby from Sunny Florida on September 14, 2020:

I planned rto mention the wildfires and totally forgot when i commented. I am saddened by the number of fires and the lives ruined. I pray they will be contained in the near future.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Good morning Eric. It's good to hear from you. By the way, I'll have an answer for you on those hamster cookies next Monday.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Bill, the air is a wee bit clearer this morning, but my throat still feels like raw meat. Have a great week my friend and enjoy the cool weather.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Shauna, most of the fires are man-made believe it or not. My family and I live in a wooded area, adjacent to Joint Base Fort Lewis, so although we are not in harms way, we certainly could if a fire were to start there.

Eric Dierker from Spring Valley, CA. U.S.A. on September 14, 2020:

Hey, a big thank you on the convection oven. When it gets hot here, it heats up the kitchen far less than a conventional. And now I know better for some cooking.

Thanks for another great one.

I am buying more oils today.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Pamela, I don't plan on EVER replacing my conventional oven. I'm too old to learn new tricks.

Linda Lum (author) from Washington State, USA on September 14, 2020:

John, I do remember that you had a dreadful fire season. Enjoy your springtime.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Ann, I would like to be able to dine outdoors but the options are few and with our older daughter living with us we must be very careful. Western Washington (where I live) is supposed to be soggy as well. People say "You live in Washington? That must be horrible. It always rains there." Not so.

Linda Lum (author) from Washington State, USA on September 14, 2020:

Flourish, we are supposed to get rain tomorrow or the next day. That will certainly help (fingers crossed).

Bill Holland from Olympia, WA on September 14, 2020:

Good news? Well, the air is supposed to be marginally better today, and progressively better as the week unfolds. That's good, right?

Be safe and have a superb week, my friend.

Shauna L Bowling from Central Florida on September 14, 2020:

Linda, what's happening on the west coast is heartbreaking. What's causing the fires? I sure hope you're not in harm's way.

Thank you for answering my convection vs conventional oven question. You gave a very detailed explanation regarding the difference between the two. My mom has one of each. I have no idea when she chooses one over the other. Perhaps, as you pointed out above, it depends on what she's making. I think I'll stick with my conventional oven.

Stay safe, Sis!

Pamela Oglesby from Sunny Florida on September 14, 2020:

This is a very detailed article with great information. I alwyas wondered if a convection oven was worthwhile. I knew it was suppose to cook some things faster but I didn't know the con side of things.

I also found the information about the oil very interesting. I am glad to know we using the healthier oils. This was a very useful, informative article, Linda.

John Hansen from Gondwana Land on September 14, 2020:

My heart goes out to all those on the West Coast of the US who are affected by the fires. It isn't long ago that we were going through the same disaster here in Australia.

Good questions and answers this week, Linda. I found the info on convection ovens vs conventional ovens interesting.

Ann Carr from SW England on September 14, 2020:

Your tables for oils are so useful, also the oven temperatures regarding convection/conventional ovens. These 'at a glance' aids are just what I like, for easy reference.

As for some 'good' news, generally the situation here regarding COVID is not brilliant, but those of us who are towing the line and distancing properly are benefitting by sitting out on the grass having picnics, going to small cafes which have tables well-spaced and many on grass so that the children can play - much more relaxing and a change of scenery. I did that twice over the weekend, with one daughter and then the other, each with my respective grandchildren - great!

I hope those fires are tamed quickly and that the air pollution recedes - these extremes must be difficult to cope with. It's seeing those sort of things that make me grateful to have a temperate, if rather soggy, climate here! At the moment it's sunny and relatively hot for our Autumn.

Keep safe and well, Linda.


FlourishAnyway from USA on September 13, 2020:

My heart is sad about the wildfires and all of those potentially in harm’s way, whether winged, two-legged, four-legged or other. Be safe. I’ve been thinking of you.

As for those ovens, I will stick with what I have. All the new cookware and conversions — sounds kinda fussy.

Related Articles