Could a modified protein be a suitable sweetener for yogurt? Researchers in Italy investigated the potential of using a protein from a berry to sweeten yogurt, with mixed results.
Sweeteners and flavors are generally added to yogurts; the natural compound generally associated with sweet taste is sucrose.
Artificial sweeteners
Several studies and reports show consumers prioritize yogurt products that are “natural” and sweet without the calories of sugar.
Aspartame is one of the most commonly used artificial sweeteners in the food industry, due to its sweetness profile.
However, recent controversies regarding the use of artificial high-intensity sweeteners, together with the increasing concern for well-being and health, have driven the use of natural high-intensity sweeteners.
Serendipity berry
Researchers at the Center of Food Innovation and Development in the Food Industry, Portici, Italy, and at the University of Naples Federico II, studied whether a modified form of monellin, MNEI, may prove to be a suitable sweetener for yogurt.
Monellin is a natural protein sweetener isolated from the fruit of the serendipity berry, Dioscoreophyllum cumminsii.
Interest in monellin is due to the fact that it is the sweetest naturally-occurring substance, up to 3,000 times sweeter than sucrose; however, the authors point to studies that suggest it is unstable to temperature increases.
The modified form of monellin, MNEI, however, exhibits enhanced stability to changes in both temperature and pH.
Four yogurts studied
The researchers studied the gelation and cooling kinetics of four yogurt samples (unsweetened or sweetened with MNEI, aspartame, or sucrose) by using a rheometer.
The four yogurts, with and without addition of a flavoring agent, were characterized from a sensory perspective.
Rheological results showed that, when added at typical usage levels, aspartame, sucrose, and MNEI did not generally affect the yogurt fermentation process or its rheological properties.
No sweet taste
Sensory results demonstrated texture attributes of yogurts with aspartame and sucrose were strongly linked to sweetness and flavor perception, but this was not true for MNEI-sweetened yogurts.
In contrast to results obtained from samples sweetened with sucrose and aspartame, MNEI protein did not sweeten the yogurt when added before fermentation.
The authors said it is possible MNEI was affected by the hydrophobic and coloumbic interactions that milk proteins undergo as the casein precipitate, as milk becomes slightly acidic during fermentation.
They added that, despite its enhanced stability compared with its natural precursor monellin, MNEI is still affected by pH changes that can promote unfolding, aggregation, and precipitation with resulting loss of sweetness.
Hence, future studies should be conducted to determine how sweet proteins behave in yogurt when added after fermentation.
Rheological and sensory performance of a protein-based sweetener (MNEI), sucrose, and aspartame in yogurt
Source: Journal of Dairy Science
