Most of us know by now that blueberries contain special phytonutrients. Can we still get those phytonutrients when we eat blueberries in muffins, jams, juices and other processed blueberry products?
In case you didn’t know, blueberries contain numerous phytonutrients. It is one of the best sources of antioxidants, with an ORAC (oxygen radical absorbance capacity) value of 9,019 micromoles per 100 grams).
But it isn’t only the ORAC value that makes blueberries so healthy. Blueberries (Vaccinium spp.) contain anthocyanins such as delphinidin, malvidin, pelargonidin and peonidin. They contain procyanidins and proanthocyanidins such as catechins and epicatechins. They contain heart-healthy flavonols such as quercetin, kaempferol and myricetin. They contain radical-scavenging polyphenols such as resveratrol and pterostilbene. They contain hydroxycinnamates such as ferulic acid, caffeic acid, and coumarins. And they contain anticancer phenols such as gallic acid and procatchuic acid. Blueberries also contain a decent amount of vitamin K and vitamin C — a quarter to a third of USDV (% daily value) for adults.
This of course relates to raw blueberries. So how about those blueberry muffins? Or blueberry jams? Or even blueberry juice or puree? How much of these powerful phytonutrients are left after cooking and/or otherwise processing blueberries?
As far as blueberry muffins go, researchers from the UK’s University of Reading tested blueberry nutrient levels before and after baking. They found that anthocyanin levels were significantly reduced by baking and otherwise cooking blueberries.
But the procyanidin levels were not significantly reduced in quantity, but they changed with respect to their molecular weight. In other words, the cooking produced higher molecular weight, more complex molecules. This process is called polymerization.
The good news is that ferulic acid and caffeic acid content remained consistent after cooking and baking, as did quercetin content. This is good because quercetin is has been shown to help prevent cancer and boost overall immunity.
This new study adds to previous research on blueberries. In 2009, researchers from the University of Arkansas studied procyanidin content remaining in blueberries after processing — including canning with syrup, pureeing, and juicing — along with six months of storage.
The research found that nonclarified blueberry juice only had 19% of the procyanidins left and clarified blueberry juice had 23% remaining.
Blueberry puree fared a little better, with 41% remaining in the puree.
Canned blueberries fared even better, with 78% of the procyanidins remaining in canned blueberries (in water — syrup-canned blueberries were worse, at 65%).
Disappointingly, six months of storage further reduced procyanidin content among all of the packaged goods. The juices only retained 8% (clarified) and 11% (nonclarified), while only 7% remained in the puree. And only 32% remained in the canned (in water) blueberries after six months of storage.
This six months of storage is important because most processed foods we buy at the store have been — when averaged out — several months at least, if not six months. Most processing of juices and canned goods will have expiry date codes that range from one to three years after the date of manufacture.
As for the disappointing levels for juice, another study at the University of Arkansas found that extrusion using heat — 180 degrees C — removed a good 40% of procyanidin content. So it appears that heat is the critical factor in removing these precious phytonutrients.
The bottom line here is that the cell walls of the blueberry present a critical part of blueberry’s phytonutrition. Within the cells walls we find lignins and something researchers from Japan’s Shinshu University refer to as “non-extractable procyanidins” or NEPCs. They determined that these NEPCs directly related to the blueberries’ ability to scavenge radicals — removing toxins from the body. In other words, extraction related to processing – which breaks down the cell walls – just doesn’t cut it if we want to gain the health benefits of blueberries.
Because baking (muffins/jams) with blueberries utilizes the whole fruit, there is greater nutrient levels, assuming they are eaten reasonably fresh after baking. But raw, fresh blueberries are still the best way to gain the benefits of this phytonutrient powerhouse.
Blueberry smoothie anyone?
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