Prebiotic apple wedges may offer alternative for gut health boost

Writing in The Journal of Food Science​, researchers from Ireland’s Teagasc report the development of a fresh-cut apple wedges with an edible coating containing the fibres oligofructose and inulin, and alginate.

“The addition of prebiotics could be especially appealing to consumers as they are essential to human nutrition in the context of dietary guidelines,”​ wrote the researchers, led by Christian Roessle.

“However, inclusion of prebiotics slightly affected the quality and sensory of the fresh-cut apple wedges, it also resulted in a variety of beneficial effects on the shelf-life, bioactive compounds, and the retention of volatiles,”​ they added.

Probiotics and prebiotics​

The study follows similar developments in the application of probiotic bacterial strains to fresh-cut apple wedges, which was promoted as a dairy-free alternative. The previous paper, published in Innovative Food Science & Emerging Technologies​, reported the development of fresh-cut apple wedges with Lactobacillus rhamnosus​ GG, with the test samples containing the bacterial strain in sufficient quantities for a probiotic effect.

According to the FAO/WHO, probiotics are defined as ‘live microorganisms which when administered in adequate amounts confer a health benefit on the host’​.

Speaking to NutraIngredients, Dr Roessle said that the rationale behind the new prebiotic-coated wedges was the same as for the probiotic apple slices.

“This product would offer a new alternative for consumers,”​ he explained. “Prebiotics are generally used in combination with dairy products and therefore using fresh-cut fruit as carrier might be especially appealing to people with lactose intolerance.” ​

Inulin and oligosaccharides​

Prebiotics are defined as "nondigestible substances that provide a beneficial physiological effect on the host by selectively stimulating the favourable growth or activity of a limited number of indigenous bacteria"​.

Roessle and his co-workers cut apple slices into wedges which still had the apple skin on, and dipped them into an solution containing sodium alginate (Qingdao Gather Great Ocean Seaweed Industry Co., China) and one from inulin (15 percent, Beneo-Orafti GR), oligofructose (35 percent, Beneo-Orafti P95), or a mixture of both (20/15 percent oligofructose/ inulin). The wedges were also exposed to an anti-browning agent called Natureseal AS1 (AgriCoat, UK), which is widely by the fresh-cut fruit industry.

A panel of 25 tasters was then used to measure the sensory aspects of both control and prebiotic-coated wedges. Dr Roessle explained that the alginate coating did affect the appearance and mouthfeel of the wedges. “The glossy appearance and slightly slippery mouthfeel is something the tasters did not associate with fresh-cut fruit,”​ he added. As such, Dr Roessle believes that the probiotic apple slices have more potential.

To conclude, the researchers wrote: “To increase the possible beneficial effects of prebiotics for the host, it could be combined with an appropriate concentration of probiotic bacteria​.”

Indeed, the Dr Roessle said that a study just published in the Journal of Functional Foods​ combined the outcomes of the pro- and prebiotics, and concluded: “Taking all the possible health benefits into account, the synbiotic apple wedges produced could be a good alternative to dairy products currently on the market.”​

The health claims issue​

Looking at the health claims situation in Europe, Roessle said: “We are aware that EFSA has not yet approved health claims for the use of Beneo-Orafti (Belgium) products such as inulin and oligofructose which are still under investigation."​

“While EFSA acknowledged that a decrease in certain gut-residing pathogens could benefit health, it said the associated levels of pre- or probiotics required to deliver such benefits had not yet been ascertained in a scientifically conclusive way, according to its own criteria. ​

“We absolutely believe that the lack of health claims has a negative effect on the uptake of such products. While we acknowledge the work of EFSA we think that the very strict regulations will damage the industry in the future,”​ he added.

Sources: Journal of Food Science​
Published online ahead of print, doi: 10.1111/j.1750-3841.2010.01902.x
“Alginate Coating as Carrier of Oligofructose and Inulin and to Maintain the Quality of Fresh-Cut Apples”​
Authors : C. Roessle, N. Brunton, R.T. Gormley, R. Wouters, F. Butler

Journal of Functional Foods​
​Published online ahead of print, doi:10.1016/j.jff.2010.09.001
“Development of potentially synbiotic fresh-cut apple slices”​
Authors: C. Roessle, N. Brunton, R.T. Gormley, P.R. Ross, F. Butler