The success of functional foods is dependent not only on the health ingredients added, but also on consumer acceptance of the finished product, and this relies heavily on the sensory properties.
The days were healthy products were deemed unappetising are coming to an end, and food manufacturers are acutely aware of the need to make healthy products taste good.
Fortifying foods with polyphenols is limited by the inherent bitter taste of the compounds. Polyphenols are antioxidant compounds with health benefits reported to range from improved cardiovascular health, to protection against certain cancers and Alzheimer's.
"A combination of [fruit flavours and cyclodextrin for suppression of bitterness] would result in a more healthy food product for consumers, as it would contain high levels of polyphenols and palatability would be achieved at lower concentrations of added sugar," wrote the authors from the Horticulture and Food Research Institute of New Zealand in the Journal of Food Science.
The researchers recruited a baker's dozen of trained tasters to evaluate five milk-based drinks fortified with polyphenols from apple or grape seed.
"The polyphenol concentration used in this study was chosen to represent the amount of polyphenol ingested when consuming one serving of fresh fruit (specifically, an apple)," explained the researchers. "A concentration of 0.2 per cent polyphenol was calculated to be commensurate with a 25-mL single-shot beverage."
The tasters noted difference not only between the polyphenol source (apple versus grape), but also between grape or apple polyphenols from different suppliers.
Both polyphenols were found to negatively impact on the flavour characteristics of the milk, particularly for the apple polyphenols.
"In particular, the high level of bitterness in apple extracts has large flavour profile implications for product development," wrote the researchers.
Solutions for health and wellness
The researchers identified various approaches to solve the detrimental effects of polyphenols on the sensory aspects of the milk. One notion was the addition of artificial sweeteners like aspartame. However, "the addition of such may also raise the argument of limited calories compared with natural ingredients," they said.
Furthermore, "keeping within the concept of a healthy product, even natural sugar addition should be kept to a minimum. Other methods of suppression should hence be considered."
Fruit flavours could be added, they said, in order to mask the bitterness of the polyphenols, while cyclodextrin, a polysaccharide produced by the enzymatic modification of starch, could be used to encapsulate the polyphenols and mask the bitterness.
"The addition of a cyclodextrin causes an inclusion complex of the bitterness molecules, meaning they cannot react with the taste buds and no bitterness is perceived," they said.
Casein molecules already present in the milk may also reduce the detrimental effects of polyphenols on flavour. Modification of the protein/polyphenol content could produce casein-polyphenol complexes, they said.
Source: Journal of Food Science
Published online ahead of print, OnlineEarly Articles, doi: 10.1111/j.1750-3841.2008.00808.x
"Using Phytochemicals to Enhance Health Benefits of Milk: Impact of Polyphenols on Flavor Profile"
Authors: L.G. Axten, M.W. Wohlers, T. Wegrzyn