My experiments with low calorie, low carb noodles – shirataki and agar noodles

I have been experimenting with two varieties of low calorie, low carb noodles at the moment – shirataki noodles and agar noodles. Both of these noodles have virtually no calories, no carbs, no fat and are essentially composed of soluble dietary fibre.

Shirataki or konjac noodles

Shirataki noodles are made from konjac, a plant of the genus Amorphophallus. I found this name interesting as ‘amorpho’ means formless or without a clearly defined shape and ‘phallus’ means penis, particularly an erect penis. It is an unusual looking plant with a single umbrella-shaped leaf up to 1.3m across growing from a large underground storage organ, known as a corm, and a dark purple spadix, which is a type of spike with small flowers, that is up to 55cm long, so I guess that is where the genus name is derived from. Konjac is native to warm subtropical to tropical eastern Asia, where it has been used as a food source and as a traditional Chinese medicine for thousands of years. (1).

Amorphophallus_konjac_(Flower_Factory)The Chinese were the first to use konjac during the Western Han Dynasty between 206BC – 08AD. Traditionally, konjac corms are washed, peeled, sliced, dried and ground to produce konjac flour, which is consumed in the form of noodles, snacks or konjac curds. Konjac was introduced into Japan in the sixth century AD as a valuable medicine. In Japanese cuisine, konjac flour is pounded with lime and water into gelatinous grey cake, a key ingredient in Japanese noodles, known as shirataki (2).

Konjac glucomannan (KGM)

The current usage of konjac in the West is in the food and nutraceutical industry, where soluble fibre from the corms, knows as konjac glucomannan (KGM) is used as a food additive or as a dietary supplement. KGM has generated interest lately due to its use as a source of dietary fibre. KGM is water-soluble and has a very high water-absorbing capacity. The β1-4 linkages between the D-glucose and D-mannose units that make up KGM cannot be broken down by salivary and pancreatic amylase, hence, KGM, passes into the colon unchanged and is fermented by the colonic bacteria (3).

The corms of A. konjac contain 49 – 60% (w/w) glucomannan, 10 – 30% (w/w) starch, 2.6 – 7% (w/w) inorganic elements including aluminium, calcium, chromium, cobalt, iron and magnesium, 5 – 14% (w/w) crude protein, 3 – 5% (w/w) soluble sugars and 3.4 – 5.3% (w/w) ash (4). When a food is said to contain ash this actually refers to any inorganic material, such as minerals. It is called ash because it is the residue remaining after heating, which removes water and all organic material, such as proteins and fats (5). Serotonin, the neurotransmitter that is believed to be responsible for feelings of well-being and happiness, has also been identified in konjac corm tissue (6). Food grade konjac flour is produced by removing the impurities, such as starch, protein, cellulose and smaller sugars from the crude flour, which has an unpleasant pungent taste and a fish-like smell (7).

The potential health benefits of KGM

The potential health benefits of KGM include anti-obesity activity, anti-hypercholesterolemia activities, prebiotic activity and anti-inflammatory activity (8). The anti-obesity activity of KGM may be attributed to the promotion of satiety by delayed gastric emptying and slowed bowel transit time and a reduced rate of food absorption in the small intestine (3). This makes sense due to the water-absorbing properties of KGM and that it is resistant to digestion until it reaches the colon. Prebiotics are non-digestible food ingredients that stimulate the growth and/or activity of certain health-promoting bacteria of the gut microbiota (9).The prebiotic effect of KGM has been supported by studies in both mice and humans. These studies have shown that dietary supplementation with KGM significantly increased the faecal concentrations of Bifidobacteria and lactobacilli, which are considered to be ‘healthy’ bacteria of the human gut, while reducing the faecal content of the potential foodborne pathogens Clostridium perfringens and Escherichia coli (10-12).

Interestingly, the latest research involving KGM is exploring the use of this polymer as a colon-targeting drug-delivery system because it can only be degraded by colonic bacterial enzymes and cannot be degraded in the stomach or small intestine (13).

Cooking with shirataki

I first came across shirataki or konjac noodles in the health food section of a major supermarket a few years ago. I really enjoyed them. They were extremely easy to prepare, the texture was similar to rice vermicelli, and they absorbed the flavour of the sauce added to them. However, they were not cheap. I had not purchased konjac noodles for ages and recently picked up a 350 gram packet for $4 at the supermarket. The next day I was in one of the Asian supermarkets that I frequent and found 300 gram packets of ribbon konjac noodles for only $1.79! I was happy and bought two packets. These noodles contain only 8 calories per 100 grams and less than 0.1 grams of carbohydrates. Use them as you would any noodle and they do not require cooking. Ensure that you rinse these noodles thoroughly as they have a somewhat unpleasant smell (do not let that turn you off), however, the taste is almost completely neutral. Below are two recipes for cold noodle salads made with shirataki.

Shirataki noodle salad 1Agar noodles

The other type of low calorie, low carb noodles that I have been experimenting with are agar noodles. I never thought I would be eating agar because agar is actually the substance that we grow bacteria on in the lab!

Agar noodlesWhat is agar?

Agar is a natural polysaccharide produced from red algae (seaweed) with a very high content of water-soluble fibre. Agar, known as kanten in Japan, has been a part of the traditional Japanese diet for over 350 years. Agar is dissolved in heated water and returns to a firm gel upon cooling (14). Agar, one of the main sources of fibre in seaweed, is not digested to any great extent in the gut and essentially passes through the gastrointestinal tract with minimal digestion (15).

The potential health benefits of agar

Studies have shown that supplementing the diet with agar can slow gastric emptying (16), which reduces the rise in blood glucose levels following a meal. This may be due to a slowing in the movement of glucose from the stomach to the small intestine or by obstructing digestion and absorption of glucose in the small intestine. It was also shown that the addition of agar to the diet can enhance weight loss in obese patients and can reduce total cholesterol levels. The enhanced weight loss may be attributed to the water absorbing properties of agar producing feelings of fullness or satiety. The mechanism by which agar reduces cholesterol is unclear, but dietary fibre has been associated with lowering cholesterol (14).

Cooking with agar noodles

This was the first time I had used agar noodles in cooking. A 1kg bag cost $4.99 at an Asian supermarket. I had some difficulties finding these noodles and actually had to get a friend to purchase them for me. It is not clearly labeled on the packet (see photo above). You can find them in the refridgerated section. These noodles have more of a chewy texture and although I soaked them in boiling water for over 10 minutes, they were still chewy, hence I used them in a stir-fry (recipe below). The noodles were no longer chewy once stir-fried and resembled the texture of any other soft noodle. Similar to shirataki, these noodles absorbed the flavour of the sauce in which they were cooked and also the colour.

In summary it would appear that both KGM and agar have some health benefits due to the extremely high fibre content. Both these substances also promote feelings of satiety due to their water-absorbing properties. I am also a huge advocate of harbouring a ‘healthy’ and diverse microbiome (the research is still relatively new in this area but we are starting to grasp some understanding of what a ‘healthy’ microbiome is), so I like the prebiotic effect of KGM. Due to the high fibre content I would not be eating these noodles too frequently as you may experience some gastrointestinal discomfort. In my opinion, if you are craving some noodles or pasta but do not want to consume the carbohydrates and calories that come with these items, try these low calorie noodles in a cold salad or in a stir-fry.

Shirataki noodle salad 2Cold shirataki or konjac noodle salads

Ingredients

Makes 2 large serves

Cold noodle salad 1

1 packet of shirataki or konjac noodles, rinsed thoroughly, soaked in hot water for about a minute then rinsed again

1/3 red capsicum

1 carrot

1 shallot, finely chopped (green part only)

1 cup wombok, finely shredded

½ cup cucumber,

½ tin chickpeas, drained and rinsed

Dressing

¼ cup soy sauce

1 tablespoon rice vinegar

½ tablespoon sesame oil

1 tablespoon lemon juice

1 teaspoon honey (replace honey with another sweetner for a vegan dressing)

¼ teaspoon red pepper powder (I just happen to have quite a bit of red pepper powder remaining after making kimchi – instructions to come) or chilli flakes

Cold noodle salad 2

1 300 gram packet ribbon konjac noodles (I untied the ribbons to create long, thin noodles), rinsed thoroughly, soaked in hot water for about a minute then rinsed again

1/3 red capsicum, diced

1 carrot, grated into ribbons

1 cup bean sprouts

½ cup cucumber, diced

½ tin chickpeas

2 shallots, finely sliced (white part)

1 clove garlic, finely minced

½ teaspoon ground ginger

Juice from ½ a lemon

1 tablespoon soy sauce

¼ teaspoon red pepper powder or chilli flakes

Dressing

2 tablespoons tahini

2 tablespoons hot water

Juice of a lemon

1 tablespoon rice vinegar

1 – 2 teaspoons honey (add 2 if you would like the dressing sweeter, repace with another sweetner for a vegan version)

2 tablespoons soy sauce

1 teaspoon sesame oil

½ teaspoon ground ginger

Utensils

Large strainer or colander

Sharp knife

Chopping board

Measuring cups and spoons

Small mixing bowl

Spoon

Large salad bowl

Non-stick fry pan for cold salad 2

Wooden spoon

Tongs to mix and serve

Method

  • For cold noodle salad 1 combine all the ingredients for the dressing in a small bowl and mix well.
  • Combine all the ingredients for the salad in a large salad bowl and mix to combine. Pour the dressing over the top and mix it through the salad.
  • For cold noodle salad 2 add the shallots, garlic and ginger to a non-stick fry pan with about ¼ cup of water. Cook until the garlic starts to soften. Add the chickpeas, lemon juice, soy sauce and red pepper powder and continue cooking until the chickpeas are slightly crunchy.
  • Combine all the ingredients for the dressing in a small mixing bowl and mix well. Combine the ingredients for the cold noodle salad, as well as the cooked chickpeas, into a large salad bowl and mix to combine. Pour the dressing over the salad and mix it through.Stir fry with agar noodles

Vegetable and chickpea stir-fry with agar noodles

Makes 2 large serves plus some remaining for lunch

Ingredients

1 vegetable stock cube

2 cloves garlic, mined

3 cm fresh ginger, finely grated

1 brown onion, finely sliced

½ a 400 gram tin of chickpeas, drained and rinsed

2 carrots, julienned

½ a red capsicum, cut into thin strips

½ head of broccoli, cut into small florets

¼ head of cauliflower, cut into small florets

1 cup frozen edamame

250 grams agar noodles soaked in hot water for about 10 minutes then rinsed

Sauce

½ cup soy sauce

2 tablespoons rice vinegar

1 teaspoon sesame oil

1 tablespoon tahini

¼ teaspoon red pepper powder or chilli flakes

1 teaspoon honey (replace with another sweetner for a vegan version)

1/4 cup hot water

Utensils

Large bowl to soak noodles

Sharp knife

Cutting board

Large strainer or colander

Measuring cups and spoons

Small mixing bowl

Spoon

Non-stick fry pan

Wooden spoon

Method

  • Crumble the vegetable stock cube into a non-stick frying pan along with ½ cup of water, the garlic, ginger and onion. Cook over a medium heat until the onion begins to go transparent. Add in the chickpeas and additional water to prevent sticking and continue cooking.
  • Add in the carrots and capsicum and continue cooking until the vegetables begin to soften. Add in the broccoli, cauliflower and edamame, adding more water as necessary to prevent sticking. Continue cooking until all the vegetables are tender but are still slightly crunchy.
  • Turn the heat down to low and add in the agar noodles. Stir well to mix the noodles through and cook until the noodles are heated and have absorbed the sauce.
  1. Hetterscheild WLA & Ittenbach S (1996) Everything you always wanted to know about Amorphophallus but were afraid to stick your nose into. Aroideana 19:7-129.
  2. Brown D (2000) Aroids, Plants of the Arum Family. (Timber Press, Portland, Oregon.).
  3. Keithley J & Swanson B (2005) Glucomannan and obesity: a critical review. Alternative therapies in health and medicine 11(6):30-34.
  4. Li B, Xia J, Wang Y, & Xie B (2005) Grain-size effect on the structure and antiobesity activity of konjac flour. Journal of agricultural and food chemistry 53(19):7404-7407.
  5. Baker M (2015) What is ash in food?
  6. Niwa T, Etoh H, Shimizu A, & Shimizu Y (2000) Cis-N-(p-Coumaroyl)serotonin from Konnyaku, Amorphophallus konjac K. Koch. Bioscience, biotechnology, and biochemistry 64(10):2269-2271.
  7. Liu PY, Lin ZS, & Guo ZX (1998) Research and Utilization of Amorphophallus in China. Acta Botanica Yunnanica Suppl. X:48-61.
  8. Chua M, Baldwin TC, Hocking TJ, & Chan K (2010) Traditional uses and potential health benefits of Amorphophallus konjac K. Koch ex N.E.Br. Journal of ethnopharmacology 128(2):268-278.
  9. Bindels LB, Delzenne NM, Cani PD, & Walter J (2015) Towards a more comprehensive concept for prebiotics. Nature reviews. Gastroenterology & hepatology 12(5):303-310.
  10. Chen HL, Cheng HC, Liu YJ, Liu SY, & Wu WT (2006) Konjac acts as a natural laxative by increasing stool bulk and improving colonic ecology in healthy adults. Nutrition 22(11-12):1112-1119.
  11. Chen HL, Cheng HC, Wu WT, Liu YJ, & Liu SY (2008) Supplementation of konjac glucomannan into a low-fiber Chinese diet promoted bowel movement and improved colonic ecology in constipated adults: a placebo-controlled, diet-controlled trial. Journal of the American College of Nutrition 27(1):102-108.
  12. Chen HL, Fan YH, Chen ME, & Chan Y (2005) Unhydrolyzed and hydrolyzed konjac glucomannans modulated cecal and fecal microflora in Balb/c mice. Nutrition 21(10):1059-1064.
  13. Liu J, et al. (2012) Preparation of konjac glucomannan-based pulsatile capsule for colonic drug delivery system and its evaluation in vitro and in vivo. Carbohydrate Polymers), Vol 87, pp 377-382.
  14. Maeda H, Yamamoto R, Hirao K, & Tochikubo O (2005) Effects of agar (kanten) diet on obese patients with impaired glucose tolerance and type 2 diabetes. Diabetes, obesity & metabolism 7(1):40-46.
  15. MacArtain P, Gill CI, Brooks M, Campbell R, & Rowland IR (2007) Nutritional value of edible seaweeds. Nutrition reviews 65(12 Pt 1):535-543.
  16. Sanaka M, Yamamoto T, Anjiki H, Nagasawa K, & Kuyama Y (2007) Effects of agar and pectin on gastric emptying and post-prandial glycaemic profiles in healthy human volunteers. Clinical and experimental pharmacology & physiology 34(11):1151-1155.

“Amorphophallus konjac (Flower Factory)” by James Steakley – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:Amorphophallus_konjac_(Flower_Factory).jpg#/media/File:Amorphophallus_konjac_(Flower_Factory).jpg

2 thoughts on “My experiments with low calorie, low carb noodles – shirataki and agar noodles

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s