Pectin: The science behind gelling
While my PhD is more focused in immunology and cell biology, I do like to experiment with food science and understand more of what goes on in the kitchen. Now that the nice weather has come to Toronto, and fresh fruits are becoming more available, I thought this would be a great opportunity to make some jam! One of the key features you need to understand about jam is pectin!
Pectin is a complex polysaccharide consisting mainly of esterified D-galacturonic acid resides in an alpha-1,4-chain. Now for those non-scientists, let me break it down a bit. Basically pectin is a compound with a bunch of sugars attached to it, more specifically, xylose, galactose and arabinose as well as a bunch of acids on the sides of it called methoxy groups. It is these methoxy groups, which help define whether the pectin will form gels quickly or slowly. Pectin extracts, which you can buy commercially are what many bakers will add to commercial jams and jelly’s to cause them to thicken.
For those of you following the specific carbohydrate diet, especially in the initial phases, pectin needs to be avoided as it is a complex sugar and can aggravate the GI tract. Based on the science I would suggest that commercial pectin be avoided as a rule with only natural pectin used in your baking, regardless of health! Here on GastroChef.org I will be posting several recipes for jams that will work better with your digestive system. The key to these recipes is understanding the pectin content in fruits, and picking the right mix!
|Fruit||Pectin Content/100g fruit|
If you have read up on the SCD diet they say not to have commercial pectin but fruits with pectin are ok, just not in the initial stages of the diet. If you read into it a bit more the story gets a little muddy. In a study by Rolandelli, R. et al. in 1988 (A long time ago!) they fed a series of rats, some with induced colitis and some without, a pectin rich diet. What they found was that in the colitis rats, the pectin diet resulted in a significant reduction in the degree of inflammation compared to those receiving a normal diet. Many other studies in mice have shown similar, decreasing in inflammation as a result of pectin in their diet! Some speculate this may be related to pectin’s ability to block intestinal nutritional absorption.
In humans, pectin has been under considerable investigation as a potential drug delivery biogel to aid in treatments for ulcerative colitis! Yay! While there are many health benefits to pectin it is important to remember that you need to limit your consumption of high pectin fruits. As a general rule the less ripe a fruit, the higher the content of pectin!
So when making jams it is important to make sure you have a mix of ripe and not-so-ripe fruits! This way you can naturally form that gel like consistency you see in store-bought jam but without the addition of potentially GI-aggravatinglevels of pectin.
At the end of the day, a jam made with only pectin found from the fruit peels along with honey as a sweetener is ok on the SCD diet! That is assuming you don’t sit down and eat jars upon jars of your homemade jam, however tempting.