Ultrasonic waves claimed to boost sponge cake quality

The application of ultrasonic waves during the batter mixing stage improved sponge cake quality in terms of lower hardness, and higher cake springiness, cohesiveness and resilience, finds a new study.

Writing in the Journal of Food Engineering, Malaysian food engineers report that ultrasound exposure could be used to improve the quality of aerated food products given that their research results showed it produced cake batter of lower density and flow behaviour index, as well as having higher viscosity, overrun, and consistency.

The authors note that as breads, sponges and biscuit owe their distinctive appeal to their aerated structure, the goal of their study was to investigate the potential use of power ultrasonic in improving this essential attribute.

As the formation of air cells during mixing is known to be important to a cake’s texture, the effect of application of ultrasonic waves during the batter mixing stage was studied in terms of batter and sponge cake quality, said the Malaysian team.

In terms of previous food processing applications, power ultrasound has been used to reduce total fermentation time of yoghurt after inoculation, to shorten the ice cream freezing process time and to reduce the drying time of orange peel, said the researchers.

They note that the technique has also been used to minimize flavour loss, induce greater homogeneity and to generate significant energy savings during heat pasteurization of sweet juices.

The study

Sponge cake batter was prepared following the “all-in” method, said the team. The ingredients used in the formulation of sponge cake were commercial low protein whole flour, emulsifier, corn starch sugar, baking powder, salt and fresh whole eggs, it added.

All the ingredients were first mixed for two minutes at 80 rpm and another nine minutes at 90 rpm in a mixer bowl, which was then put in an ultrasound bath system with adjustable power of 1 kW, 1.5 kW or 2.5 kW for different durations ranging from 3 to 9 minutes.

The results

The engineers found that the effect of ultrasound exposure on batter and cake properties were more “prominently positive when mixed at 2.5 kW for the entire mixing duration of 9 minutes while detrimental effects were found when 1.5 kW was used for 6 min.”

“Ultrasound treatment seems to help in increasing the overrun or aeration in cake batter during mixing when used for longer durations and at the highest power level of 2.5 kW,” said the team.

The ultrasound duration was more effective than the ultrasound power in creating changes and giving effects to the cake batter properties, the researchers noted.

Aerated batter density exposed to three minutes of ultrasound at all power levels, 1 kW, 1.5 kW and 2.5 kW showed little difference with the control, found the researchers.

“Overall evaluation of textural properties of cakes made from batter mixed at 2.5 kW for 9 min of ultrasound exposure showed that it possessed hardness of 12 per cent lower than the control, and 10 per cent lower in both gumminess and chewiness, while the cake springiness, cohesiveness and resilience were slightly higher than [the] control,” said the team.

Source: Journal of Food Engineering