Food Ways: Sea biscuits


OLDEST SHIP BISCUIT. This specimen appears at the Maritime Museum in Kronborg Castle, Elsinore, Denmark. The biscuit dates from 1852. Image: Paul A. Cziko (

It has been an interesting journey doing the research on sea biscuits and I am sure there is more information I haven’t found doing a quick internet search. Sea biscuits are the Navy’s equivalent of hardtack, which is a relatively new comer as it was named by the 19th Century American army. Given the simple recipe (mix flour and salt with water to make a dough, roll out into patties, bake in a medium oven for 30 min at least twice) these biscuits were probably around in prehistoric times and still surviving in some hidden cave somewhere. These biscuits last longer than flour as they have a lower moisture content and water activity. One disadvantage is that sea biscuits will absorb moisture if the humidity increases. This was a problem when Royal Navy ships first traveled in the tropics.

When I travel, even on short journeys, I am in the habit of carrying some food and water with me. Travel delays on trains and planes have been part of my travel experience and I prefer to know I have food rather than hope I can buy something if necessary.  Travelers need food that has a long shelf-life, is robust, safe to eat, and calorie/nutrient dense. Many travelers’ food is dried as removing the moisture  extends the shelf life by essentially making the food inedible to bacteria. While removing water has the advantage of stopping bacterial growth, it doesn’t always give us a food that is robust and could stand up to the rigors of travel. There have been a number of times I have reached into my rucksack for a cookie/biscuit and found crumbs. Not the snack I was hoping for!

The sea biscuit has more in common with Terry Pratchett’s Dwarf’s rock cakes than any modern cookie or cracker. So robust that, typically sea biscuits need to soaked overnight or smashed with a hammer or rock to able to eat it. Sea biscuits are the original cracker that was crumbled into New England chowder, probably because that was the only way the biscuits could be eaten. The British navy used to bake/dry their biscuits 4 times. So if you think biscotti are hard to eat without dunking, double the force needed to bite into a sea biscuit and book that trip to a dentist to replace your teeth. They were so hard that apparently an American civil war soldier wrote a letter on the side of a hardtack and mailed it with the address on the other side and it survived in the mail without any protection. No wonder British soldiers were envious of American food rations in World War 2.

In the process of making sea biscuits you knead the flour and water together. This allows for gluten formation and most of the recipes have a 2:1 ratio of flour to water which is perfect for gluten formation. Gluten is the protein that gives bread its springy texture and the network of gluten stays in place once heating is complete which means that bread keeps its structure after baking. While soft bread goes stale very quickly due to the retrogradation of starch, the starch in hardtack is probably all retrograded before leaving the oven. An interesting question would be to find out how much starch granules hydrate and swell in making of sea biscuits. Is enough for the starch molecules to gelatinize? Perhaps the water is removed too quickly for gelation and retrogradation occurs very quickly with little rearrangement of the starch molecules. (Confused – see my post on starch here!)

If you want to make your own sea biscuits there are lots of recipes online due to reenactors and survivalists wanting a food that is traditional and/or last a long time. They are also popular in Hawai’i and Alaska. Personally I would prefer water biscuits or Scottish oatcakes carefully wrapped than a food that is hard to eat. Trail mix would be more desirable still. However, if a zombie apocalypse is ever threatened, I know what I could bake to help my long term survival.


All references visited on 29 January 2018

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Science on Sunday: Glycemic Index

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

Non-Enzymatic Browning Introduction 2

Food tastes best when browned.

Food tastes best when browned.

Food in always complex unless you are studying something quite simple such as a beverage with few ingredients (vitamin water, anyone?).  Even sucrose has a complex chemistry, more of which I will share in a future post.  So individual NEB reactions cannot be isolated in food.  Quite often intermediates and products from one reaction become intermediates in another reaction, especially in the Maillard reaction. Thus, most food chemistry textbooks use Non-Enzymatic Browning (NEB) as synonymous with the Maillard reaction. However, the other NEB reaction cause browning in food without the use of enzymes.

Both caramelization and lipid oxidation cause browning in certain foods, i.e. sugar-based and fried foods, respectively. Ascorbic acid degradation is significant in food with a low pH (high acidity) especially in citrus juices.  The reaction of flavanoids is important in highly colored foods as the colorful anthocyanins degrade and lose their color.  The reaction of flavanoids may also be important in soy protein, but less because of a color change and more due to a lose of isoflavones.

NEB Intro Part 1

Non Enzymatic Browning

My major interest in food chemistry is how food changes during processing and storage.  I am especially interested in how color changes take place.  The reactions I am interested in are called Non Enzymatic Browning reactions to differentiate them from the browning that occurs when you cut an apple or banana, which involves an enzyme.

Non enzymatic browning (NEB, non enzymic browning) reactions are the most important reactions in food, and, no, I am not biased.   Just image the aroma of melting chocolate, freshly baked bread or  a roasting leg of lamb, the golden color of a croissant, the dark amber color of a well brewed beer; caramels, toast.  These are all caused NEB reactions.

There are five different NEB reactions and I intend over the next few months to write about each of them:

  1. Caramelization – browning of sugar, especially sucrose
  2. Lipid Oxidation – the oxidation of fats and oils; including rancidity
  3. Break down of flavonoids – highly c0lored compounds can also lose their color
  4. Degradation of ascorbic acid (Vitamin C) – AsA is unstable even without oxygen
  5. The Maillard Reaction –  reaction between carbonyl compounds and amino acids

Numbers (3) and (4) are not typically on a list of NEB reactions, but I did my thesis on ascorbic acid browning and it definitely goes brown without oxygen and without enzymes.  The degradation of flavonoids is one I have added and came to me in flash of inspiration when at a conference.  I am sharing it with you now, so this is new even though I had the idea three or four years ago.

More later…

Knitting Delays Dementia

Mum heard on the BBC World Service that knitting can reduce depression in older women:

Apparently physical therapists and doctors have noticed that old ladies (and perhaps men – not mentioned) who are in pain and depressed, improved a lot when they took up knitting.  They used less medication, were more cheerful and their  memories improved.

Doctors think it may be the movements in knitting that help to calm patients.  They also suggest that knitting groups overcome feelings of isolation and making nice things makes the ladies feel  less useless.

They are starting a proper research programme in Bath to sort out the different factors.

I did a quick search and all I could find was this on BBC Health, which is more about dementia than depression:

Those who had during middle age been busy reading, playing games or engaging in craft hobbies like patchworking or knitting were found to have a 40% reduced risk of memory impairment.

So pick up those needles and stop your mind from deteriorating.

My Hero: Marie Curie

Conveniently the topic for the next Scientiae Carnival, Role Models of Women Making History, dovetailed nicely with the next exercise for the Total Leadership process.  I found the examples in the book about Total Leadership hard to follow on from as they were both about family members that had overcome adversity and personal challenges. These stories are very interesting, but while I admire my family greatly and I know they have undertaken personal challenges, to me a hero is someone who has done something beyond every day living.  So I chose Marie Curie.

Teaching chemistry to freshmen undergraduates makes me realize how white male dominated it was especially at the beginning of the twentieth century.  A few women stand out in my mind as having been successes despite the system – Dorothy Hodgkin and Rosalind Franklin are two from the mid to late twentieth century that come to mind.  Marie Curie (1867 – 1934) succeeded as a chemist and physicist at an earlier time than these two and from within the system.  I admire her because she dedicated her life to science to such an extent that she left her home country, Poland, to do research at a better institution in Paris.  This was definitely unusual for women at that time.  When she found her scientific niche, she carried out her research at the highest level winning two Nobel prizes.  Every scientist dreams of winning one, but two is outstanding.

The first Nobel prize was the prize for Physics awarded in 1903 to Marie Curie, Pierre Curie and Henri Becquerel

“in recognition of the extraordinary services they have rendered by their joint researches on the radiation phenomena discovered by Professor Henri Becquerel.”

The second, the 1911 Nobel Prize in Chemistry, was awarded

“in recognition of her services to the advancement of chemistry by the discovery of the elements radium and polonium, by the isolation of radium and the study of the nature and compounds of this remarkable element.”

Marie Curie with her daughters

Marie Curie with her daughters

In addition to being a brilliant hardworking scientist she was also a wife and a mother.  Imagine Marie Curie, who discovered radiation, worrying about Pierre having holes in is socks or Irene getting enough fruit to eat*.

I connect to Marie Curie and see her as a role model because she gave her all to science despite the conventions and expectations of women at her time.

*I am sure she had governesses and housekeepers and was probably quite bourgeois, but still she did it.  She could have just stayed at home and done what every other middle class woman of the late nineteenth and early twentieth centuries was doing.


Wikipedia on Marie Curie

Susan Quinn (1995) Marie Curie – A Life, Heinemann, London

Simple Sugars: Fructose, glucose and sucrose

Glucose, fructose, sucrose

Glucose, fructose, sucrose

Simple sugars are carbohydrates. Glucose and fructose are monosaccharides and sucrose is a disaccharide of the two combined with a bond.  Glucose and fructose have the same molecular formula (C6H12O6) but glucose has a six member ring and fructose has a five member ring structure.

Fructose is known as the fruit sugar as its make source in the diet is fruits and vegetables. Honey is also a good source.

Glucose is known as grape sugar, blood sugar or corn sugar as these are its riches sources. Listed in food ingredients as dextrose.

Sucrose is the sugar we know as sugar or table sugar. Typically extracted as cane or beet sugar. If sucrose is treated with acid or heat, it hydrolyzes to form glucose and fructose.  This mixture of sucrose, glucose and fructose is also called invert sugar.

Nutritionally, these sugars are the same as they all provide 4 Cal/g. This is true for starch and other digestible carbohydrates too. Of the three sugars, fructose is the sweetest and glucose the least sweet, so typically less fructose can be used than table sugar (sucrose) – if sucrose has a sweetness of one, fructose is 1.7 and glucose 0.74

Fructose is more soluble than other sugars and hard to crystallize because it is more hygroscopic and holds onto water stronger than the others. This means that fructose can be used to extend the shelf life of baked products more than other sugars.

Wikipedia has lots information on sugars, including information on the three I am interested in fructose, glucose and sucrose.