Scientists are exploring options for transforming fruit and vegetable by-products -like peels or pulp discarded during processing- into nutritious food ingredients and supplements. Now, researchers reporting in ACS Journal of Agricultural and Food Chemistry have shown that blueberry and persimmon waste can be made into antioxidant-rich powders that might have beneficial effects on gut microbiota.

Fruit and vegetable powders have become popular as a way to add beneficial compounds, such as polyphenols and carotenoids (two types of antioxidants), to the diet, either by consuming the powders directly or as an ingredient in food products. However, in many cases these compounds are present at similar or even higher levels in by-products compared to those in other parts of the fruit or vegetable.

Noelia Betoret, María José Gosalbes and colleagues wanted to study how digestion could affect the release of antioxidants and other bioactive compounds. They also wanted to determine the effects of the digested powders on gut bacterial growth.

The researchers obtained powders from persimmon peels and flower parts, and from the solids left behind after making blueberry juice. The type of powder, drying method, fiber content and type of fiber determined the release of antioxidants during a simulated digestion.

Their findings indicate that persimmon and blueberry waste powders could be included in food formulations to boost the content of carotenoids and anthocyanins, which could have a positive impact on human health, the researchers say.