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.


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Food Ways: An Introduction

Plane wing at dawn

Dawn in the air

So I am stuck on a plane, eating rather tasteless penne and cheese while reading Rob MacFarlane’s “The Old Ways”. While Rob writes about walking in a way that resonates, he rarely eats. My memory of walking seems to be centered around food whether it be the Cadbury’s Fruit and Nut squares that Dad and I ate to keep us going, the corned beef and ketchup sandwiches that Dad loved, our discovery when visiting the Lake District for the first time of Kendal Mint Cake or the afternoon teas at the end, food was very much part of my venturing into the British countryside. In fact, I missed that most when I started hiking in the US as there was no pub lunch and no afternoon tea.

The second chapter in “The Old Ways” is an anthology of writers who have written about walking. So many books to read. I realized that I want to write about food the way Rob writes about wildness. I think food might be harder to do; food is civilized and urbane; cuisine has defined what we consider to be a meal, snack, beverage, fruit and vegetable. Culture has defined food down to when we should eat what; including the meals on planes. Why are we provided food on planes? What is the history behind air travel and food. After all food isn’t bought to you on a train or a bus. Stage coaches had to stop at inns so passengers could get food. On boats I guess food was provided or were steerage passengers expected to bring their own food with them?

What is the history of food on the move?

I read somewhere that our taste is affected by the pressure/altitude/air circulation on planes. Unfortunately these food providers aren’t aware of that fact. The overcooked broccoli was the only thing with any kind of flavor, even though its texture had been destroyed. The penne in white sauce was flavorless – the texture was redeemed by some minor crunchy bits where it had been overcooked. I have never liked cooked carrots, so I can’t judge what their flavor. No wonder my seatmate bought her own sandwiches.

I tried to search food for journeys on Google. The problem is that there are lots of journeys centered around food; mostly exploring the food of a new-to-you culture. I tried portable food and discovered that Lewis and Clark took portable soup with them on their journey. It wasn’t very popular apparently! GLEW by name, gluey in nature. The Smithsonian has a good summary of food in space. Of course we have popularity of Tang® and freeze-dried food thanks to NASA.

I checked through my library of food books. In “Pickled, Potted, and Canned” Sue Shephard has a chapter on “Great Journeys” that discusses some of the history of food on the move. Wealthy travelers on familiar routes were able to use monastery guest houses, hospices, and inns. Poorer people typically carried food with them, as did all people travelling less well known roads. A list of portable foods throughout the world includes a lot of dried or cured food, such as dried fruit, fish, meat, hardtack, jerky, pemmican and Johnny or journey cakes. Later in the chapter, Sue discusses polar explorers who weren’t so great at nutrition. I remember being told by one of my nutrition professors that Scott (of the Antarctic) partly failed because he didn’t believe that fruit was necessary to prevent scurvy. Sue agrees that Scott failed because of malnutrition and exhaustion.

As a food scientist, I am interested in the descriptions of what happens to food during travel. The shelf-life of dried meats and fruit dramatically decreased when ships reached the tropics. This is probably caused by a mixture of the high humidity and heat. At the other end of the climate spectrum, explorers in the Arctic and Antarctic found that the extreme cold changed their food. It must have been a shock to see that molasses had mostly solidified and that dried fruit was frozen tight in their wooden barrels. “Sugar formed a funny compound” is one description. Now I want to find out what that meant; what happens to sugar at 32 oC.


Dismukes K and Petty J I (2002)Food for Spaceflight, NASA,

MacFarlane, R. (2012) The Old Ways. Penguin, London.

Rupp R (2014) The Luke-Warm, Gluey, History of Portable Soup. National Geographic,

Shephard, S (2000)  Pickled, Potted, and Canned. Simon and Schuster, New York. Chapter 13 “Great Journeys”.

Smithsonian Air and Space Museum (nd) Food in Space.

Walker H (editor) (1996) Food on the Move: Proceedings of the Oxford Symposium on Food and Cookery, 1996. Prospect Books, Devon.


9/52 Diptych

From seeds to seedlingsI 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.


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