Agave syrup has been touted as an organic, raw food, healthy alternative to sugar but what exactly is it?
The agave species is native to México and the southwestern United States of America. They are neither a cactus nor a relative of the aloe plant which they resemble. There are over 200 varieties of this plant. The agave was known as “metl” in the lingua franca of the Aztec empire and it occupied a place of significant importance to the Mesoamericans. This plant supplied food, drink, medicine, fibre for clothing and cordage as well as writing and building materials in ancient times and the modern use of this plant doesn’t differ much today for those Mexicans who live closer to the land than us “civilised” folk.
The flowers, sap and heart of the plant (called a piña due to its superficial resemblance to a pineapple once its “leaves” have been trimmed off) are all edible. The skin of the leaves (called pencas) can also be peeled off and used to wrap food prior to cooking to both protect and flavour the dish. The piña is a dense fibrous ball which needs to be cooked before it is useful. The cooking breaks down the starches in the plant and converts them to edible sugars. Modern cooking methods involve a steam autoclave but in the old days they were cooked for several days in an underground pit reminiscent of the Maori hangi. The juices that are then extracted from crushing the cooked piña are used to make agave syrup (or they are fermented and then distilled to make the drinks we know as tequila and mezcal).
The production of agave syrup in this manner is similar to how high fructose corn syrup is created through the processes of enzymatic or thermal hydrolysis (1). Back in the day (and probably still done at the local level) agave syrup was made from the sap of the agave. When the agave flowers (once every 7 to 40 years depending on the variety) it sends up a flower stalk called a quiote which looks remarkably like dinosaur sized asparagus.
This stalk is cut out of the plant to create a wound which will exude up to several litres of fluid a day. This liquid, called aguamiel (honey-water) is a sweet and refreshing liquid which can be drunk as is. If left exposed to the air for several days wild yeasts begin to ferment this liquid into a slightly viscous, mildly alcoholic (about 4-7%) liquid called pulque. (see various Posts on Pulque). Pulque is an extremely nutritious probiotic drink that is almost a meal in itself. In México it is said that the only thing pulque lacks for being meat is the bones. If aguamiel is heated gently the water evaporates and a syrup is formed (much like the sap of the maple tree). Agave syrup/nectar IS NOT made this way.
Fructans (which include inulin and agavin) are extracted from the agave by thermal or enzymatic hydrolysis. Thermal hydrolysis is the heat treatment of filtered agave “juice” (the liquid obtained from the autoclaved and crushed piñas) at temperatures between 80 and 121°C for differing periods of time (4). Enzymatic hydrolysis involves filtering the expressed juice several times to remove solids, it is then exposed to 80°C temperature to inactivate the saponins in the liquid and a mixture of exo-inulinase and endo-inulinase enzymes are used to break down the fructans to produce fructose (3)(5). Inulin and agavin are polysaccharides and are considered a form of soluble fibres and are prebiotic. As prebiotics they promote the growth of intestinal bacteria and may increase absorption of both calcium (12), magnesium (13) and iron (15). Both these manufacturing processes prevent agave syrup from being a “raw” food and it must be noted that the higher the fructose level is then the lower the inulin level will be as it is the inulin that is hydrolysed to produce the fructose. The high fructose content of this sweetener is also touted as a health benefit because fructose does not spike blood sugar levels in the same manner as glucose. This gives agave syrup a low G.I. level when compared to glucose (6) and as a result it is sometimes recommended as a healthy sweetener for diabetics. The glycaemic index (of a 50g portion) of glucose is 96 while that of fructose is only 23 (8). Using agave syrup as a “healthy option for diabetics” is a potentially dangerous train of thought. Agave syrup is up to 80% fructose (7) and contains nearly more than twice the content of fructose than high fructose corn syrup (7). This can cause problems as fructose tends to be converted in the liver into triglycerides which are stored immediately as fat through de novo lipogenesis (10). High levels of triglycerides raise the risk factors for heart disease. As the liver is the only organ that can metabolise fructose in significant amounts it is quickly overloaded and there is belief amongst some researchers that this can lead to non-alcoholic fatty liver disease (9).
When consumed in large amounts fructose can contribute to insulin resistance and greatly raises the risk of type II diabetes and Metabolic Syndrome (11). Fructose as it is found in nature (i.e. in the apple you’re eating) does not have the same effect on the body as high fructose syrups as the physical mass of the apple produces a feeling of satiety and you stop eating sooner. The apple will also come with a host of vitamins, minerals and enzymes that are not contained in a fructose syrup. High fructose syrups provide the calories without the satiety and you eat more than you need (calorically speaking). This is one of the factors causing obesity amongst those who consume “fast food” meals regularly. It must also be noted that inulin is considered a FODMAP and must be avoided if undergoing a low FODMAP diet/regime (14). Some soluble fibres (i.e. beta glucan from oats) can actually lower cholesterol and blood sugar levels.
The organic nature of these products can also be questioned. Exo-inulinase and endo-inulinase are enzymes manufactured from the fungus Aspergillus niger or the Pseudomonas species of bacteria (endo-inulinase in particular)(16). Aspergillus niger can cause a disease called black mould on some fruits and vegetables and is a common contaminant of food. It is considered of low danger to humans and is recognised as GRAS (generally recognised as safe) by the US FDA (17). Pseudomonas are a species of gram negative bacteria several of which are pathogenic towards humans. Some species of pseudomonas are used to produce bioethanol and another sweetener (xylitol) from agave biomass (18) and some are sprayed on cereal seeds or soils to control crop pathogens. According to the Australian Certified Organic Standard of 2017 (19) section 6.1.28 regarding the processing and preparation of organic products “The extraction of any product shall only take place with water, ethanol, plant and animal oils and naturally occurring products such as vinegar, carbon dioxide or nitrogen. These shall be of a quality appropriate for their purpose.” There are similar admonitions on the use of pesticides. I believe that the methods used for industrial agave syrup production skirt the very edges of these requirements and as such the “organic” nature of most of these products is at the very least suspect.
Glycaemic Index Values of Sweeteners in Comparison with Agave Nectar
Maltodextrin 110 – 150
Maltose 105 – 150
High fructose corn syrup 70 – 90
Honey 50 – 80
Lactose 40 – 60
Fructose 20 – 25
Agave syrup 15 – 25
Xylitol 5 – 10
Low G.I. – 55 or less / Moderate G.I. – 56 to 69 / High G.I. 70+
The University of Sydney Database : http://www.glycemicindex.com/foodSearch.php
- Method of producing fructose syrup from agave plants : US Patent Issued on December 8, 1998 : No. 614349 filed on 1996-03-12 : https://web.archive.org/web/20070926220317/http://www.patentstorm.us/patents/5846333.html
- Mark W. Chase, James L. Reveal, and Michael F. Fay. 2009. “A subfamilial classification for the expanded asparagalean families Amaryllidaceae, Asparagaceae, and Xanthorrhoeaceae”. Botanical Journal of the Linnean Society 161(2):132-136.
- Christian Michel-Cuello, Imelda Ortiz-Cerda, Lorena Moreno-Vilet, Alicia Grajales-Lagunes, Mario Moscosa-Santillán, Johanne Bonnin, Marco Martín González-Chávez, and Miguel Ruiz-Cabrera. : Study of Enzymatic Hydrolysis of Fructans from Agave salmiana Characterization and Kinetic Assessment : Scientific World Journal. 2012 : Published online 2012 May 2. doi: 10.1100/2012/863432
- Diana B. Muñiz-Márquez, Juan C. Contreras, Raúl Rodríguez, Solange I. Mussatto, Jorge E. Wong-Paz, José A. Teixeira & Cristóbal N. Aguilar (2015) Influence of thermal effect on sugars composition of Mexican Agave syrup, CyTA – Journal of Food, 13:4, 607-612, DOI: 10.1080/19476337.2015.1028452
- Mauricio García-Aguirre, Victor A. Sáenz-Álvaro, Mayra A. Rodríguez-Soto, Francisco J. Vicente-Magueyal, Enrique Botello-Álvarez, Hugo Jimenez-Islas, Marcela Cárdenas-Manríquez, Ramiro Rico-Martínez and Jose L. Navarrete-Bolaños. : Strategy for Biotechnological Process Design Applied to the Enzymatic Hydrolysis of Agave Fructo-oligosaccharides To Obtain Fructose-Rich Syrup : Departamento de Ingeniería Química-Bioquímica, Instituto Tecnológico de Celaya, Avenida Tecnológico s/n, C.P. 38010, Celaya, Guanajuato, Mexico : J. Agric. Food Chem., 2009, 57 (21), pp 10205–10210 : DOI: 10.1021/jf902855q
- David S. Ludwig, Joseph A. Majzoub, Ahmad Al-Zahrani, Gerard E. Dallal, Isaac Blanco, Susan B. Roberts : High Glycemic Index Foods, Overeating, and Obesity : American Academy of Pediatrics : March 1999, VOLUME 103 / ISSUE 3
- Jamie L. Willems and Nicholas H. Low : Major Carbohydrate, Polyol, and Oligosaccharide Profiles of Agave Syrup. : J. Agric. Food Chem., 2012, 60 (35), pp 8745–8754 : Department of Food and Bioproduct Sciences, University of Saskatchewan : DOI: 10.1021/jf3027342
- Xiaosen Ouyang, Pietro Cirillo, Yuri Sautin, Shannon McCall, James L.Bruchette, Anna Mae Diehl, Richard J.Johnson, Manal F.Abdelmalek : Fructose consumption as a risk factor for non-alcoholic fatty liver disease : Journal of Hepatology : Volume 48, Issue 6, June 2008, Pages 993-999
- David Faeh, Kaori Minehira, Jean-Marc Schwarz, Raj Periasamy, Seongsoo Park and Luc Tappy : Effect of Fructose Overfeeding and Fish Oil Administration on Hepatic De Novo Lipogenesis and Insulin Sensitivity in Healthy Men : Diabetes 2005 Jul; 54(7): 1907-1913.
- Heather Basciano, Lisa Federico and Khosrow Adeli. : Fructose, insulin resistance, and metabolic dyslipidemia : Nutrition & Metabolism20052:5 : https://doi.org/10.1186/1743-7075-2-5
- Abrams S, Griffin I, Hawthorne K, Liang L, Gunn S, Darlington G, Ellis K (2005). “A combination of prebiotic short- and long-chain inulin-type fructans enhances calcium absorption and bone mineralization in young adolescents”. Am J Clin Nutr. 82 (2): 471–6. doi:10.1093/ajcn.82.2.471. PMID 16087995.
- Coudray C, Demigné C, Rayssiguier Y (2003). “Effects of dietary fibers on magnesium absorption in animals and humans”. J Nutr. 133 (1): 1–4. PMID 12514257.
- Andoh A, Tsujikawa T, Fujiyama Y (2003). “Role of dietary fiber and short-chain fatty acids in the colon”. Curr Pharm Des (Review). 9 (4): 347–58. PMID 12570825.
- Tako E, Glahn RP, Welch RM, Lei X, Yasuda K, Miller DD (2007). “Dietary inulin affects the expression of intestinal enterocyte iron transporters, receptors and storage protein and alters the microbiota in the pig intestine”. Br J Nutr. 99 (Sep): 1–9. doi:10.1017/S0007114507825128. PMID 17868492.
- Dong Hyun Kim, Yong Jin Choi, Seung Koo Song, Jong Won Yun : Production of inulo-oligosaccharides using endo-inulinase from a pseudomonas sp. : Biotechnology Letters : April 1997, Volume 19, Issue 4, pp 369–372
- “Inventory of GRAS Notices: Summary of all GRAS Notices”. US FDA/CFSAN. 2008-10-22. Archived from the original on 11 October 2008. Retrieved 2008-10-31.
- Xiong, Lili & Maki, Miranda & Guo, Zhiyun & Mao, Canquan & Qin, Wensheng. (2014). Agave Biomass is Excellent for Production of Bioethanol and Xylitol Using Bacillus Strain 65S3 and Pseudomonas Strain CDS3. Journal of Biobased Materials and Bioenergy. 8. 10.1166/jbmb.2014.1453.