By Surbhi JainSep 23 2022Reviewed by Susha Cheriyedath, M.Sc.In an article recently published in the journal Current Opinion in Food Science, researchers discussed the enhancement of the effectiveness of plant-based proteins and drinks with ultrasound.
Study: Ultrasound processing to enhance the functionality of plant-based beverages and proteins. Image Credit: 5PH/Shutterstock.com
Background
Juice is a convenient and useful way to consume the nutrients and bioactive compounds found in fruits and vegetables, which are essential components of the human diet as sources of carotenoids, phenolics, vitamins, flavonoids, and minerals. Additionally, there is a growing market for plant-based ingredients and goods which could work as milk substitutes. The global trend toward plant-based foods is due to several factors, including the rise in the population of vegans, vegetarians, and flexi-vegans, concern over the environment's impact on food production, sustainability, and animal welfare, in addition to the health benefit, e.g., allergenicity of milk proteins.
Fruit and vegetable juices are particulate solid-liquid systems made up of serum of water and soluble substance, suspension of cells and their fragments, including fibers and cell walls. Particle-particle and particle-serum interactions are encouraged by cell disintegration and particle size reductions, which increase suspension stability, cloudiness, and rheological property variation.
About the Study
In this study, the authors explored how ultrasound could be used to change the structural properties of proteins and plant-based beverages such as juices and milk to produce novel capabilities. The discussion included both positive and negative aspects, such as improving protein solubility and modifying its digestibility, increasing the bioaccessibility of nutrients and bioactive compounds, and exposing nutrients and bioactive compounds to the environment to cause degradation or limited microbial inactivation. It was evident that ultrasound technology could be utilized as a useful tool to enhance the qualities of plant-based beverages and could assist in the production of products with clean labels and favor health. However, the scale-up to industry remained a challenge that require both research and technological advancement.
The team discussed the three most representative examples, which described the current research on using ultrasound processing to improve the functionality of plant-based beverages. The first one was fruit and vegetable juices, produced top-down by disassembling the plant organism on a smaller scale. The second was plant-based milk, produced top-down or bottom-up by assembling a new product from ingredients, and the third was the use of vegetable proteins.
The researchers stated that the primary goals of using ultrasound in these products were to preserve nutrients and bioactive substances, increase their digestibility and accessibility to the human body, improve rheology, physical stability, and interaction with water, and ultimately achieve desired sensory impact, better health aspects, and wellbeing promotion.
Observations
With five minutes at 300 W, 13 minutes at 55 W/cm2, and three minutes at 400 W, respectively, ultrasound was effective for increasing the physical stability of various kinds of milk, which could be linked to changes in particle size of proteins and lipids and rheology. According to several reports, these drinks included bioactive substances like isoflavones and phytosterol, and had strong antioxidant properties. Plant-based milk could contain antinutritional substances, including saponins, phytates, and protease inhibitors.
The nutritional and bioactive qualities of plant-based milk could be positively impacted by ultrasound. It reduced the trypsin inhibitor by 52% and increased the protein digestibility by 7.4% in soybean milk at 400 W, 25 kHz, for 16 minutes. However, no appreciable improvement was discovered for almond milk at 400 W, 20 kHz, for 16 minutes. Furthermore, hydrated soybeans treated with ultrasound at 400 W, 24 kHz for 20 minutes produced milk with 63-84% more isoflavone content than untreated beans.
According to many studies, ultrasonography was rarely sufficient to provide the necessary microbial inactivation in plant-based milk. A 400 W probe for three minutes on peanut milk resulted in a reduction of 0.9 logs while treating almond "milk" with 130 W, 20 kHz ultrasound for 8 minutes at 80% power resulted in a reduction of up to 1.3 logs for Escherichia coli and Listeria monocytogenes.
The most popular device was an ultrasonic probe with a range of nominal powers in the range of 130–400W and frequencies in the range of 20–25 kHz. After processing hemp seed protein isolates with ultrasound at amplitudes between 45 and 65% for five to 10 minutes, solubility increased. This was attributed to the partial unfolding of protein molecules and increased protein-water interaction.
Conclusions
In conclusion, this study elucidated that protein modification using ultrasound processing is an intriguing and promising method that could enable the use of a greater variety of plant proteins and the development of those proteins' uses in the food sector.
The authors mentioned that more research is required to explain how processing conditions could alter the functions of plant beverages, taking into account vegetable sources and food products for various demands. They also stated that research in material science is required to create more durable probe tips, and reactor engineering studies are required to construct machinery that can process the volumes of the food sector.
The team believes that ultrasound technology could be a useful tool for enhancing the qualities of plant-based beverages, facilitating the production of products with clean labels, and enhancing wellbeing.
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References
Rojas, M. L., Kubo, M. T. K., Miano, A. C., et al. Ultrasound processing to enhance the functionality of plant-based beverages and proteins. Current Opinion in Food Science, 100939 (2022). https://www.sciencedirect.com/science/article/abs/pii/S2214799322001412.
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