Saturday, April 15, 2017

My sugar findings

The posts in this blog is usually about technology subjects. However I'm on vacation for the last week and have spent several days reading about sugar and products containing it, mostly from Wikipedia. Below is the summary of my findings. Please note that I did not study neither chemistry not biology since 9th grade, so please bear with me for possible inaccuracies.

Appetizer: In the year of 2015, the world has produced 177 million tons of sugar (all types combined). This is 24 kilograms per person per year, or 70 gram per day, and surely much higher in industrialized countries.

Monosaccharides

AKA “Simple sugars”. These are the most basic types of sugar - they can not be further hydrolyzed to simpler compounds. Those relevant for humans are glucose, fructose and galactose - they are the only ones that human body can directly absorb through small intestine. Glucose can be used directly by body cells, while fructose and galactose are directed to liver for further pre-processing.

Glucose is not “bad” per-se - it’s a fuel of most living organisms on earth, including humans. However high amounts of glucose, as well as other monosaccharides, can lead to insulin resistance (diabetes) and obesity. Another problem related to intake of simple sugars, is that they are fueling acid-producing bacteria living in mouth that leads to dental caries.

Sources

Primary sources of monosaccharides in human diet are fruits (both fresh and dried), honey and, recently, HFCS - High Fructose Corn Syrup. On top of that, inverted sugar is also in use, but I will cover it separately later on.

While fruits contain high percentage of fructose, it comes together with good amount of other beneficial nutrients, e.g. dietary fiber, vitamin C and potassium. For that, fruits should not be discarded because of their fructose content - they overall are healthy products and commonly are not a reason for overweight or obesity. For example, two thirds of Australians are overweight or obese, while an average Australian eats only about one piece of fruit a day.

Note: It’s quite common in the food industry to treat dried fruits with sulfur dioxide, which is a toxic gas in its natural form. The health effects of this substance are still disputed, but since it’s done to increase shelf life and enhance visual appeal of the product, i.e. to benefit producer and not end user, I do not see a reason to buy dried fruits treated with it. Moreover, I’ve seen products labeled as organic, that still contained sulfur dioxide, i.e. the fruits themselves were from organic origin, but were treated with sulfur dioxide.

Honey, one the other hand, while generally perceived as “healthy food” is actually a bunch of empty calories. An average honey consists of 80% of sugars and 17% of water, particularly, 38% of fructose and 31% of glucose. Since honey is supersaturated liquid, containing more sugar than water, glucose tends to crystallize into solid granules floating in fructose syrup.

Note: one interesting source of honey is a honeydew secretion.

Finally, HFCS, is a sweetener produced from corn starch by breaking its carbohydrates into glucose and fructose. The resulting solution is about 50/50% on glucose/fructose (in their free form), but may vary between manufactures. This sweetener is generally available since 1970, shortly after discovery of enzymes necessary for its manufacturing process. There were some health concerns about HFCS, however nowadays they are generally dismissed - i.e. HFCS is not better of worth than any other added sugar, which, again, in case of excess intake can lead to obesity and diabetes.

Disaccharides

Disaccharide is a sugar that is formed by two joined monosaccharides. The most common examples are:
  • Lactose: glucose + galactose
  • Maltose: glucose + glucose
  • Sucrose: glucose + fructose
Disaccharides can not be absorbed by human body as they are, but require to be broken down, or hydrolyzed, to monosaccharides. To speed up the process and allow fast enough absorption, enzymes are secreted by small intestine, where disaccharides are hydrolyzed and absorbed. Dedicated enzyme is secreted for each disaccharide type, e.g. lactase, maltase and sucrase. Insufficient secretion, or lack thereof, results in body intolerance to a certain types of disaccharides, i.e. inability to absorb them in small intestine. In such case they are passed on into large intestine, where various bacteria metabolize them and the resulting fermentation process produces gases leading to detrimental health effects.

Another issue with disaccharides is that they, together with monosaccharides, provide food food to acid-producing bacteria leading to dental caries. Sucrose particularly shines here allowing anaerobic environments that boost acid production by the bacteria.

Lactose is naturally found in dairy products, but some sources say that it’s often added to bread, snacks, cereals, etc. I don’t quite remember lactose being listed on products, at least in Israel, and though I did not research on the subject, my guess is this is because it will convert products to milk-kosher, and thus can limit their consumption by end user. I did not study lactose any further. Maltose is a major component of brown rice syrup - this is how I’ve stumbled upon it initially.

Sucrose, or “table sugar”, or just “sugar” is the king of disaccharides, and all of the sweeteners together. The rest of this post will be mainly dedicated to it, but let's finish with maltose first.

Maltose

My discovery to maltose started with reading nutrition facts of organic, i.e. perceived “healthy”, candy saying “rice syrup”. Reading further, I found out that it’s a sweetener produced by breaking down starch of the whole brown rice. The traditional way to produce the syrup is to cook the rice and then to add small amount of sprouted barley grains - something that I should definitely try at home some time. Most of the current production is performed using industrial methods, as one would expect.

The outcome is, again, sweet, empty calories, for good and for bad of it. Traditionally prepared syrup can contain up to 10% of protein, however it’s usually removed in industrial products. Other than that, again, - empty calories.

Sucrose

Without further adieu, let's get to sucrose, most common of all sugars. Since Wikipedia has quite good and succinct article on sucrose, I will only mention topics that particularly thrilled me.

Note: Interestingly enough, before introduction of industrial sugar manufacturing methods, honey was the primary source of sweeteners in most parts of the world.

Humans extract sucrose from cane sugar from about 500BC. The process is quite laborious and involves juice extraction from crushed canes, boiling it to reduce water content, then, while cooling, sucrose crystallizes out. Such sugar is considered Non-centrifugal cane sugar (NCS). Today processes are quite optimized and use agents like lime (don’t confuse with lemon), and activated carbon for purification and filtering. The result is raw sugar, which is then further purified up to pure sucrose and molasses (residues).

In 19th century, sugar beet plant joined the sugar party. Slightly different process is used, but it also results in sucrose and molasses. Beet’s molasses are considered unpalatable by humans, while cane molasses are heavily used in food industry.

While it’s generally agreed that regular white sugar (sucrose) is “bad”, in recent years there is trend to substitute it with various kinds of brown sugars, which are considered healthier. Let’s explore what brown sugars are.

Brown sugar is a sucrose based sugar that has a distinctive brown color due to presence of molasses. It’s either obtained by stopping refinement process at different stages, or by re-adding molasses to pure white sugar. Regardless of the method, the only non-sugar nutritional value of brown sugars comes from their molasses, and since typical brown sugar does not contain more than 10% of molasses, its difference to white sugar is negligible, nutrition wise. Bottom line - use brown sugars, e.g. demerara, muscovado, panela, etc. because you like their taste and not because they are healthier.

This leads to conclusion that molasses is the only health-beneficial product of sugar industry. The strongest, blackstrap molasses, contains significant amount of vitamin B6 and minerals like calcium, magnesium, iron, and manganese, with one tablespoon providing 20% of daily value.

The only outstanding detrimental effect of sucrose that I have discovered (compared to other sugars) is its increased effect on tooth decay.

Misc

Caramel

Heating sugars, particularly sucrose, produces caramel. Sucrose first gets decomposed into glucose and fructose and then builds up new compounds. Surprisingly enough, this process is not well understood.

Inverted sugar

Inverted sugar syrup is produced by splitting sucrose into its components - fructose and glucose. The resulting product is alluringly sweet, even compared to sucrose. The simplest way to obtain inverted sugar is to dissolve some sucrose in water and heat it. Citric acid (1g per kg of sugar) can be added to catalyze the process. Baking soda can be used later to neutralize the acid and thus remove the sour taste.

Sucrose inversion occurs when preparing jams, since fruits naturally contain acids. Inverted sugar provides strong preserving qualities for products that use it - this is what gives jams relatively long shelf life even without additional preservatives.