22 Aug 2014
24 Mar 2011
I was having a hard time deciding how to do my diptych for the week’s photographic challenge. Last year I went over the top and then I got discouraged about taking photos every week as it took so much time in Photoshop. This year, I didn’t collaborate and I did a very simple theme. I used PowerPoint rather than Photoshop.
Copyright © 2011 cgadavies. All rights reserved.
13 Mar 2011
One of the problems with science is how it is reported in magazines and newspapers. Also how it is reported on the web can be a problem. This problem came to light for me when I was reading the free magazine “Better Nutrition”. In the February issue there was a short article on “The best weight management diet” which talked about a New England Journal of Medicine article which showed that high protein-low glycemic index diets were better for maintaining weight loss. This sound realistic and was confirmed by reading the article, but what peeked my interest was the table of glycemic index values in the Better Nutrition article because apparently sourdough bread has a lower GI (54) than white bread (100).
This did not seem possible as sourdough bread is essentially made from the same ingredients as white bread with a different starter is added instead of yeast for proofing. There is nothing in the process of making sourdough bread that should change the carbohydrates, which are from wheat flour.
So I looked up how glycemic index was measured. What I found was that glycemic index (GI) ranks foods by how quickly they increase blood sugar (glucose) levels. Foods that increase blood sugar rapidly after being consumed have a high GI. For example, honey has a GI of 85 and sucrose, table sugar, has a GI of 70. Conversely foods which are slowly digested and absorbed have a low GI. Examples of these foods are green vegetables (GI = 15) and dark chocolate with greater than 70 % cocoa solids (GI = 22).
GI is measured by feeding measured portions of the test food containing 10 – 50 grams of carbohydrate to 10 healthy people after an overnight fast. Blood samples are taken at 15-30 minute intervals over the next two hours and used to construct a blood sugar response curve. The area under the curve (AUC) is calculated to reflect the total rise in blood glucose levels after eating the test food. The results for a test food is divided by the results of the standard containing the same amount of carbohydrate, either glucose or white bread are used as standards, and multiplied by 100. The result gives a relative ranking for each tested food. There is some concern, firstly that the standards used are different and secondly two hours after a meal is too short. Food is known to stay in the stomach for over 4 hours, so longer term blood glucose monitoring might be better.
The glycemic index was developed at the University of Sydney (Australia) originally to aid people with diabetes control their blood sugar levels. Low GI diets are useful for people with diabetes as it allows them to regulate their blood sugar levels and this in turn helps with insulin levels and may reduce insulin resistance for people with Type II diabetes.
So the more I read, the less likely it seemed that sourdough bread could have a lower glycemic index than white bread, which by the way, in some measurements of GI is set as the reference with a GI of 100 and in others, where glucose is the reference, white bread has a GI of 70. Yes, not even the measurements of GI are standardized.
Interestingly it seems that the reason the high protein/low glycemic index diets work is that protein fills you up and after eating a meal that is high in protein you are more satisfied.
Thomas Meinert Larsen, et al, Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance N Engl J Med 2010; 363:2102-2113 doi:10.1056/NEJMoa1007137
22 Jun 2010
26 Jan 2010
19 Jan 2010
Michael Pollan has a new book which gives the rules (guidelines) towards health eating. My copy is on its way from Amazon and I’ll let you know what I think when I’ve read it. In the meantime here is an interview from the Daily Show, links to an article in the YT, to an interview at SlashFood and to an excerpt of the book at ABCnews.
(Hat-tip: Thanks to colleagues RG and RR for the original link.)
BTW, Tropicana Trop50 is disgusting, unfortunately proving Michael Pollan’s point about food manufacturing. Once my current carton is gone, I’m sticking to straight orange juice. If I want less sugar, I’ll dilute it.
18 Aug 2009
I really should just sent you to Exploratorium which has an excellent section on sugar chemistry, but sugar chemistry is so cool, that I have share it with you myself. In fact sugar chemistry is so interesting that it supports a whole sector of the food industry. I am, of course, talking about candy. Food Scientists typically divide the candy industry into chocolate and non-chocolate candy and most of the non-chocolate candy is made from different forms of sucrose.
If you remember sugar is the common name for sucrose, which has the very confusing chemical name of β-D-fructofuranosyl-α-D-glucopyranoside which is a fancy way of saying that it is made up of glucose and fructose. In this post, I will interchange the words sugar and sucrose, but in chemistry sugar refers to saccharides which are considered to be small carbohydrates.
The most important property of sucrose is its high solubility over a wide temperature range. The different sugar candies are made by heating a sugar-water solution, as the heating time increases water evaporates. This increases the sugar concentration and the temperature of the solution increases. The temperature of the solution is dependent on sugar concentration:
Candy technologists not only control the sugar concentration by heating the sugar-water mixture to a predetermined temperature, they also control the final physical arrangement of the sugar molecules by the other ingredients added and by the way they treat the sugar-water mixture while it is cooling. This determines whether the solution sets in a crystalline form or not. The non-crystalline form is also known as amorphous. Thus sugar candies are divided into crystalline and amorphous.
Crystalline candies include fudges, fondant and rock candies. Amorphous candies include cotton candy, hard candy and brittles, where the sucrose has been set into a glass, and caramel and taffy, which are chewy rather than hard.
Wikipedia Candy#Sugar Stages
Harold McGee On Food and Cooking 2nd Edition p681
30 Jun 2009
These look delicious but they are still as hard as a rock. When they are ripe, I hope I get them before the birds do. This is my first year for raspberries and I don’t know how greedy the birds will be. Yeah, these are not meant to fruit their first year, but I couldn’t resist getting a few raspberries.
Raspberries must be my favorite berry, if not my favorite fruit.