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Does blending food in a blender affect its enzyme activity and does the length of blending time make a difference?

There is very little published research on the health value of raw foods or the enzymes that are contained in them. We've seen no evidence that the enzymes found in food can be absorbed from the digestive tract and become active in the body. Some percentage of the enzymes found in raw food are active in the digestive tract itself once the food has been chewed and swallowed, although the circumstances here are complicated. Each enzyme only works at a specific temperature, degree of acidity, and in conjunction with other nutrients. All of these factors are constantly changing in the digestive tract, and in a food being chewed, swallowed, and digested. For all of these reasons, the activity of food enzymes in the digestive tract is highly variable. No food could be guaranteed to have enzymes that would automatically be active in our digestive tract.

All processing of food exposes the food to air and some degree of physical alteration. Juice extractors and blenders subject foods to enormous physical change. We haven't seen research studies showing changes in protein fractions as a result of blender processing, but we would expect such changes to occur. Enzymes, of course, are proteins, and we would be surprised if blender processing didn't produce some changes here. More importantly, most of the fiber and many of the nutrients contained in whole foods are contained in the pulp that is typically discarded after juicing. Separation of the pulp from the watery juice also separates out a large percentage of the food's nourishment. Unless this pulp is added back into the juice and consumed, this process greatly lowers the food's nutritional value. If the whole foods are processed in a blender and then consumed without filtering or straining, that method is superior to juice extraction if juice extraction involves removal and discarding of the pulp. Most commercially juiced fresh juices, contain between 0-4 grams of total fiber per 8 ounces. About one pound of fresh carrots, containing about 15 grams of fiber, would be required to make an 8-ounce cup of fresh carrot juice containing 0-2 grams of fiber. That's a loss of more than 80%. One further disadvantage with juicing or blender processing is the removal of chewing from the consumption process. The chewing of food is important for nourishment, and many processes in the digestive tract are only activated under the circumstance of chewing.