Japanese scientists have reported that monoacyl sugar alcohols could be 'very promising emulsifiers' and could offer an alternative to the widely used monoacyl glycerols.
Propelled by consumer health concerns, food makers are under pressure to design tasty foodstuffs that cut back on the fat. And with the changing needs of the food industry, there has been a growing demand for multi-purpose' emulsifiers, said Frost & Sullivan.
Monoacyl glycerols are widely used in the food industry as both emulsifiers and anti-microbial agents, and have been extensively studied. But new research from Kyoto University in Japan suggests that the monoacyl sugar alcohols, similar in structure, could also be used as emulsifiers.
"Although the monoacyl sugar alcohols are surface active and seem to be promising food emulsifiers, no systematic studies have been done on their application as food emulsifiers," explained authors Junkui Piao and Shuji Adachi in the journal Innovative Food Science and Emerging Technologies (doi: 10.1016/j.ifset.2006.04.002).
The researchers investigated the particle size distribution and stability against storage (both room temperature and cold storage) of oil in water emulsions of monoacyl sugar alcohols (in the water phase). The monoacyl sugar alcohols were synthesised by esterification of the corresponding sugar alcohol sorbitol, xylitol; erythtirol, ribitol, and glycerol.
Each emulsion was prepared to have a concentration of 0.5 millimoles per kilogram and soy bean oil was used as the oil phase.
"Fine emulsions with the median diameters of ca. 2 micrometres and with relatively narrow distributions were produced for every tested emulsifier, indicating that all the monoauroyl sugar alcohols and glycerol have an emulsifying ability," reported Piao and Adachi.
However, when stored at 25 degrees C for five days, only the monoauroyl erythritol emulsion continued to display a small particle size distribution.
The superiority of the monoauroyl erythritol emulsion was also observed when the researchers measured the retort resistance of the emulsion. "Because the retort treatment of food is a common method to extend its shelf life, the ability to suppress demulsification is also one of the abilities for which food emulsifiers are preferred to possess," explained Piao and Adachi.
None of the studied emulsions were stable when frozen at minus 30 degrees Celsius and then thawed, a result that indicates that these emulsifiers may not be suitable to use in frozen foods like ice cream.
"In terms of emulsifying and emulsion-stabilising abilities, the monoauroyl erythritol would, overall, be the best emulsifier among the tested ones,"concluded the researchers.